Specification for welded construction. Tu for the manufacture of a welded beam. Assembly and welding works

Description of the welded structure (truss), its purpose and justification for the choice of material. Selection and justification of assembly and welding methods, its mode. Calculation of the amount of deposited metal, the consumption of welding consumables, electricity. Quality control methods.

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1. Technology section
1.6 Welding modes
Conclusion
Bibliography

1. Technology section

1.1 Description of the welded structure, its purpose

Application area

Trusses are widely used in modern construction, mainly for covering large spans: bridges, roof systems of industrial buildings, sports facilities. Also, this design can be used by specialists in the production various kinds pavilions, stage structures, awnings and podiums.

Principle of operation

If several rods are arbitrarily fastened on hinges, then they will randomly rotate around each other, and such a structure will be, as they say in structural mechanics, "changeable", that is, if you press on it, it will fold like the walls of a matchbox fold. It is quite another matter if you make an ordinary triangle out of rods. Now, no matter how much you press, the structure will be able to take shape only if you break one of the rods, or tear it away from the others. This design is already "immutable". The truss design contains these triangles. Both the tower crane boom and complex supports, they are all made up of small and large triangles.

It is important to know that since any rods work better in compression-tension than in breaking, the load on the truss should be applied at the junction points of the rods.

In fact, the truss rods are usually connected to each other not through hinges, but rigidly. That is, if you take any two rods and cut them off from the rest of the structure, then they will not rotate relative to each other. However, in the simplest calculations, this is neglected and it is assumed that there is a hinge.

DesignelementsAndnodesfarms.

Truss elements, as a rule, are made of paired profiles. This allows them to be paired in knots using the so-called gussets or gussets - steel sheets to which each element of the truss is attached by riveting or welding. The use of welding always makes it possible to significantly reduce the weight of roof trusses. The cross section of the elements, the number of rivets, the length of the welds are determined by the strength calculation and depend on the load forces acting on the truss in the elements and on its span.

The upper belt is usually made in the form of a T-section from two unequal corners ranging in size from 100 x 75 mm to 200 x 120 mm, made up of narrow shelves, the lower belt is made of isosceles corners ranging in size from 65 x 65 mm to 150 x 150 mm, but can also be used uneven corners. In cases where the belts carry the load within the panel and therefore bend, they are made from paired channels No. 14 - 22.

Lattice elements are usually constructed of tee or cruciform section from isosceles corners ranging in size from 60 x 60 mm to 80 x 80 mm. To simplify the work, it is desirable that all elements of the farm be selected from no more than 5 - 6 different profiles.

Truss belts have, as a rule, a length significantly exceeding the maximum length of rolled profiles (12 - 15 m). In addition, it is impractical to manufacture entire trusses 20 - 30 m long at the plant, which would be inconvenient to transport to the construction site. Therefore, farms are mostly made from two halves, arranging joints in the belts in the middle of the span.

In order to prevent additional stresses from bending in the truss rods, the axes of all the rods in the node must converge at one point or, as they say, be centered (shown by the dotted line). The rods of welded trusses are centered along the centers of gravity of the elements, and the rods of riveted trusses are centered along the lines of placement of rivets, called risks.

Steel17GS ( heat-resistant low-alloy) is used: for the manufacture of apparatus bodies, bottoms, capacitive equipment, flanges and other welded parts operating under pressure at temperatures from - 40 ° C to + 475 ° C; parts and elements of steam and hot water pipelines of nuclear power plants (NPP), with a design ambient temperature not higher than +350 ° C at an operating pressure of less than 2.2 MPa (22 kgf / cm 2); electric-welded longitudinal pipes of strength group K52 for the construction of gas pipelines, oil pipelines and oil product pipelines; straight-seam electric-welded expanded pipes intended for the construction of high-pressure pipelines.

Design name - farm. Welded structure steel class - 17GS. The material of the rods is C345 steel, the material of the gussets is C345 steel.

Dimensions: Length - 24 m.;

Height - 3.7m.;

Width - 0.35 m.

The mass of the structure is 1952 kg.

1.2 Weldment material justification

Justification of the material of the welded structure should be carried out taking into account the following basic requirements:

ensuring strength and rigidity at lowest cost its manufacture, taking into account the maximum savings of metal;

guaranteeing conditions for good weldability with minimal softening and reduced plasticity in the areas of welded joints;

ensuring the reliability of operation of the structure under given loads, at variable temperatures in aggressive environments.

The determination of the steel structure is carried out according to the Scheffler diagram.

welded structure truss welding

The structure is welded from steel grade 17GS. The mechanical properties of steel 17GS are given in table 1. Chemical composition material to be welded is given in Table 2.

Table 1 - Mechanical properties of steels

Table 2 - Chemical composition of steel

For this, the equivalent value of chromium is initially calculated for steel:

Eq Cr = %Cr + %Mo + 2%Ti + 2%Al + %Nb + 1.5%Si + %V=

0,3+0+0+0+0+1,50,6+0=1,2 % (1)

And then the equivalent nickel value is calculated:

Eq Ni = %Ni + 30%C + 30%N + 0.5Mn=

0,3+300,2+300,008+0,51,4=7,24 % (2)

According to the values of Eq Cr and Eq Ni, a point corresponding to the steel structure is plotted on the Scheffler diagram (Figure 1).

Figure 1 - Scheffler diagram

1.3 Specification for the fabrication of a welded structure

Specifications for the manufacture of a welded structure provide for specifications for basic materials, welding consumables, as well as requirements for workpieces for assembly and welding, for welding and for welding quality control.

As the main materials used for the manufacture of critical welded structures operating under dynamic loads, alloy steels according to GOST 19281-89 or ordinary carbon steels of at least grade St3ps according to GOST 380-94 should be used.

Compliance of all welding consumables with the requirements of the standards must be confirmed by the certificate of the supplying plants, and in the absence of a certificate - by the test data of the plant's laboratories.

In manual arc welding, electrodes of at least type E42A in accordance with GOST 9467-75 with a rod made of Sv-08 wire in accordance with GOST 22496-70 should be used.

Welding wire must be free of rust, oil and other contaminants.

The requirements for blanks for welding provide that the parts to be welded from sheet, shaped, sectional and other rolled products must be straightened before assembly for welding.

After rolling or bending, the parts must not have cracks and burrs, tears, waviness and other defects.

The edges of parts cut with scissors should not have cracks or burrs. The cut edge must be perpendicular to the surface of the part, the allowable slope in cases not specified in the drawings must be 1: 10, not more than 2 mm.

Dents after straightening and curvilinearity of welded edges should not go beyond the established tolerances for gaps between welded parts. Limit deviations of angular dimensions, if they are not specified in the drawings, must correspond to the tenth degree of accuracy of GOST 8908-81.

Parts supplied for welding must be accepted by the Quality Control Department.

The assembly of the parts to be welded must ensure the presence of a specified gap within tolerance along the entire length of the joint. The edges and surfaces of parts at the locations of welds to a width of 25-30 mm must be cleaned of rust, oil and other contaminants immediately before assembly for welding.

Parts intended for contact welding at the joints must be cleaned from both sides of scale, oil, rust and other contaminants.

Details with cracks and tears formed. during manufacture, are not allowed for assembly for welding.

These requirements are provided with technological equipment and appropriate tolerances for assembled parts.

When assembling, force adjustment is not allowed, causing additional stresses in the metal.

The allowable displacement of the welded edges relative to each other and the size of the allowable gaps should not exceed the values established for the main types, structural elements and dimensions of welded joints in accordance with GOST 14771-76, GOST 235182-79, GOST 5264-80, GOST 11534-75, GOST 14776-79, GOST 15878-79, GOST 8713-79, GOST 11533-75.

Local increased clearances must be eliminated before assembly for welding. It is allowed to weld gaps by surfacing the edges of the part, but not more than 5% of the weld length. It is forbidden to fill the enlarged gaps with pieces of metal and other materials.

The assembly for welding must ensure the linear dimensions of the finished assembly unit within the tolerances indicated in Table 3, the angular dimensions according to the 10th degree of accuracy of GOST 8908-81 in the absence of other accuracy requirements in the drawings.

The cross section of tacks is allowed up to half the cross section of the weld. Tacks should be placed at the locations of the welds. The applied tacks must be cleaned of slag.

Tacking of welded structures during assembly must be carried out using the same filler materials and requirements as when making welds.

Assembly for welding must be accepted by the quality control department. During transportation and tilting of metal structures assembled for welding, measures must be taken to ensure the preservation of the geometric shapes and dimensions specified during assembly.

Only certified welders who have a certificate establishing their qualifications and the nature of the work to which they are admitted should be allowed to weld critical assembly units.

Welding equipment must be provided with voltmeters, ammeters and pressure gauges, except in cases where the installation of devices is not provided. The condition of the equipment must be checked daily by the welder and fitter.

A practical inspection of welding equipment by the department of the chief mechanic and power engineer should be carried out at least once a month.

The manufacture of steel welded structures should be carried out in accordance with the drawings and the assembly and welding process developed on their basis.

The technological process of welding should provide for such an order of suturing in which internal stresses and deformations in the welded joint will be the smallest. It should provide maximum possibility of welding in the lower position.

Carry out welding work by methods not specified in technological process and this standard, without agreement with the chief specialist in welding, it is prohibited. Deviation from the welding modes indicated in the process charts, the sequence of welding operations is not allowed.

The surfaces of the parts at the location of the welds must be checked before welding. Edges to be welded must be dry. Traces of corrosion, dirt, oil and other contaminants are not allowed.

It is forbidden to strike an arc on the base metal, outside the boundaries of the seam, and to bring the crater to the base metal.

In appearance, the weld should have a uniform surface without sagging and sagging and with a smooth transition to the base metal.

At the end of welding, before the product is presented to the quality control department, welds and surfaces adjacent to them must be cleaned of slag, sagging, metal spatter, scale and checked by the welder.

In contact spot welding, the depth of electrode indentation into the base metal of the welding point should not exceed 20% of the thickness of the thin part, but not more than 0.4 mm.

The increase in the diameter of the contact surface of the electrode during welding should not exceed 10% of the size established by the technical process.

When assembling for spot welding, the gap between the contacting surfaces at the locations of the points should not exceed 0.5.0.8 mm.

When welding stamped parts, the gap should not exceed 0.2.0.3 mm.

When spot welding parts of different thicknesses, the welding mode should be set in accordance with the thickness of the thinner part.

After assembling the parts for welding, it is necessary to check the gaps between the parts. The size of the gaps must comply with GOST 14776-79.

The dimensions of the weld must comply with the drawing of the welded structure in accordance with GOST 14776-79.

In the process of assembly and welding of critical welded joints, step-by-step control should be carried out at all stages of their manufacture. The percentage of parameter control is specified by the technological process.

Before welding, check the correct assembly, the dimensions and quality of the tacks, compliance with the geometric dimensions of the product, as well as the cleanliness of the surface of the welded edges, the absence of corrosion, burrs, dents, and other defects.

During the welding process, the sequence of operations established by the technical process, individual seams and the welding mode should be controlled.

After completion of welding, quality control of welded joints should be carried out by external inspection and measurements.

Fillet welds are allowed convex and concave, but in all cases, the leg of the seam should be considered the leg of an isosceles triangle inscribed in the section of the weld.

Inspection can be carried out without the use of a magnifying glass or using it with an increase of up to 10 times.

The control of the dimensions of welds, points and detected defects should be carried out with a measuring tool with a division value of 0.1 or special templates.

Correction of the defective section of the weld more than twice is not allowed.

External inspection and measurement of welded joints should be carried out in accordance with GOST 3242-79.

1.4 Determining the type of production

All enterprises producing metal structures belong to the serial type of production.

Serial production is much more efficient than single production. equipment is used more fully, and the specialization of jobs ensures labor productivity. Depending on the number of products in a batch and the value of the coefficient of consolidation of operations, small-scale, medium-scale and large-scale production is distinguished.

The annual program of 140 designs corresponds to small-scale production with a design weight of 17568 kg.

1.5 Selection and justification of assembly and welding methods

The assembly of welded structures in single and small-scale production can be carried out by marking using the simplest universal devices (clamps, staples with wedges), followed by tacking using the same welding method as when making welds.

In the conditions of serial production, assembly for welding is carried out on universal plates with grooves, equipped with stops, clamps with various clamps. On universal slabs, assembly should be carried out only in cases where the project specifies welded structures of the same type, but different in size. With the help of templates, you can assemble simple welded structures.

In addition, assembly fixtures reduce the assembly time and increase labor productivity, facilitate working conditions, increase the accuracy of work and improve the quality of the finished welded structure.

The parts assembled for welding are fastened in fixtures and on stands using various types of screw, manual, pneumatic and other clamps.

The choice of one or another welding method depends on the following factors:

thickness of the welded material;

the length of the welds;

requirements for the quality of products;

the chemical composition of the metal;

expected performance;

cost of 1 kg of deposited metal;

Among the methods of electric arc welding, the most used are.

manual arc welding;

semi-automatic welding in shielding gases;

automatic welding in shielding gases and submerged arc.

Due to low productivity and high labor intensity, manual arc welding (MAW) is unacceptable in serial and mass production. It is mainly used in single and small batch production.

1.6 Welding modes

The welding mode is a set of characteristics of the welding process that ensures the production of welded joints of specified sizes, shapes, and quality. For all arc welding methods, such characteristics are the following parameters: electrode diameter, welding current strength, arc voltage, electrode movement speed along the seam (welding speed), current type and polarity. With mechanized welding methods, one more parameter is added - the feed rate of the welding wire, and when welding in shielding gases - the specific consumption of shielding gas.

Welding mode parameters affect the shape and dimensions of the weld. Therefore, in order to obtain a high-quality weld of a given size, it is necessary to choose the right welding modes based on the thickness of the metal being welded, the type of joint and its position in space. The shape and dimensions of the weld are influenced not only by the main parameters of the welding mode; but also technological factors, such as the type and density of the current, the inclination of the electrode and the workpiece, the stick-out of the electrode, the structural shape of the connection and the size of the gap.

The calculation of the welding mode is always made for a specific case, when the type of connection, the thickness of the metal being welded, the wire grade, flux or shielding gas, as well as the method of protection against the flow of molten metal, are known. Therefore, before starting the calculation, it is necessary to establish in accordance with GOST 8713-79, or in accordance with GOST 14771-76, the structural elements of a given welded joint.

For fillet welds, the penetration depth can be taken:

N PR \u003d 0.6d \u003d 0.65 \u003d 3 mm (3)

1.7 Selection of welding consumables

General principles selection of welding consumables are characterized by the following basic conditions:

ensuring the required operational strength of the welded joint, i.e. determined level of mechanical properties of the weld material in combination with the base metal;

ensuring the necessary continuity of the weld metal (without pores and slag inclusions or with the minimum size and number of these defects per unit length of the weld);

the absence of hot cracks, i.e. obtaining weld metal with sufficient technological strength;

obtaining a complex of special properties of the metal, seam (heat resistance, heat resistance, corrosion resistance).

The choice of welding consumables is made in accordance with the accepted method of welding.

The choice and justification of specific types and grades of welding consumables should be made on the basis of literary sources, taking into account the requirements.

The choice of steel wire for mechanized welding methods is made in accordance with GOST 2246-70, which provides for the production of steel welding wire for welding with a diameter of 0.3 to 12 mm.

Welding wire for welding aluminum and its alloys is supplied in accordance with GOST 7881-75.

Table 3 - The ratio of the diameter of the electrode and the thickness of the parts to be welded

Table 4 - Selection of electrodes for welding

Material of the workpieces to be welded	Type of electric	Coating type electrode	Electrode brand	Note
low carbon				DC welding
			UONI-13/45,SM-11	DC and AC current
medium carbon				The current is constant. Used for welding non-critical structures
				The current is constant. For welding critical structures
Low carbon, low alloy steels				For welding heat-resistant steels such as 12XM, 15XM. DC and AC current
				For welding steel type 15X. DC current

Table 5 - Materials for welded joints of steel structures performed by manual electric arc welding

Groups of structures in climatic regions
		covered electrodes according to GOST 9467-75*


2, 3 and 4 - in all areas, except for I 1 , I 2 , II 2 and II 3
	S345, S345T, S375, S375T, S390, S390T, S390K, S440, 16G2AF, 09G2S
1 - in all areas; 2, 3 and 4 - in areas I 1 , I 2 , II 2 and II 3	S235, S245, S255, S275, S285, 20, Vst3kp, Vst3ps, Vst3sp
	S345, S345T, S375, S375T, 09G2S
	S390, S390T, S390K, S440, 16G2AF

Following from tables 3,4,5, we make the choice of an electrode:

Brand UONI-13/45

DC and AC current

Diameter 5-6mm

A group of structures in climatic regions 2,3 and 4 - in all regions, except for I1, I2, II2 and II3.

1.8 Selection of welding equipment, technological equipment, tools

In accordance with the established technological process, the welding equipment is selected. The main selection conditions are:

technical characteristics of welding equipment that meet the accepted technology;

smallest dimensions and weight;

the highest efficiency and the lowest power consumption;

minimum cost.

The main condition when choosing welding equipment is the type of production.

So, for single and small-scale production, for economic reasons, cheaper welding equipment is needed - welding transformers, rectifiers or semi-automatic welding machines, giving preference to equipment operating in a shielding gas environment with a power source - rectifiers.

ChooseRectifierweldingVD-313 designed for manual arc welding with coated electrodes of steel products at direct current. Welding current is continuously adjustable by mechanical movement of the horizontal magnetic shunt. The arc current calibration of the VD-313 welding rectifier is made on the outer surface of the shunt. The original shunt control mechanism dramatically reduces the time required to change the welding mode. The VD-313 welding rectifier is distinguished by its simplicity, reliable design, low weight, mobility, and in terms of welding properties it is not inferior to the well-known VD-306 welding rectifier. VD-313 is produced with and without instruments.

Figure 2 - RectifierweldingVD-313

TechnicalcharacteristicsrectifierweldingVD-313:

Mains voltage, V 3x380 Limits of welding current regulation, A 60-315 Rated welding current, A 315 Rated operating mode with a welding cycle duration of 10 minutes, PN, % 60 Rated operating voltage, V 32 No-load voltage, V, not more 70 Primary power, kVA, not more than 26 Weight, kg 95 Overall dimensions (LxWxH), mm 964х570х827

RectifierweldingVD-313:

Infinitely variable welding current No moving windings Forced cooling

There isrectifierblock (diodebridge) for this welding rectifier.

1.9 Determination of technical standards for assembly and welding times

The total time to perform the welding operation T sv, hour, is determined by the formula:

T sv \u003d t about + t p. + t in + t obs + t p; where h;

t p. \u003d 10% t o \u003d 0.14.613 \u003d 0.413 h;

t in \u003d t e + t cr + t ed + t cl \u003d 0.08 + 0.142 + 0.105 + 0.05 \u003d 0.377 h;

t obs \u003d (0.06 ... 0.08) t about \u003d 0.323 h.

T sv \u003d 4.613 + 0.413 + 0.377 + 0.323 + 0.33 \u003d 6.06 hours.

1.10 Calculation of the amount of deposited metal, consumption of welding consumables, electricity

The mass of deposited metal is determined by the formula:

kg;

At semi-automatic welding flux consumption per product Gf, kg, is determined by the formula:

G el \u003d (1.4 ... 1.6) M U NM \u003d 32.909 kg;

Table 3 - Summary table of material consumption

1.11 Calculation of the amount of equipment and its loading

The required amount of equipment is calculated according to the technical process.

We determine the actual fund of the operating time of the equipment Ф d, h, according to the formula:

F D \u003d (D p t n -D pr t c) K pr K s \u003d (2538-91) 0.951 \u003d 1914.25 h;

We determine the total labor intensity, programs T o, n-h, welded structures according to the operations of the technical process:

assembly: h-h;

welding: h-h;

plumbing: n-h.

Table 4 - List of labor input for the manufacture of welded structures

We calculate the amount of equipment C p for the operations of the technical process:

the accepted amount of equipment С n =1,1,1pc.

Calculation of the equipment load factor.

For each operation:

Calculated average:

1.12 Calculation of the number of employees

We determine the number of production workers (assemblers, welders). The number of main workers P op is determined for each operation by the formula:

people;

determine the number of auxiliary workers P BP, according to the formula:

people;

determine the number of employees P sl, according to the formula:

people;

including the number of managers (masters) R hands, according to the formula:

people;

We determine the number of specialists (technologists) Р special, according to the formula:

people;

We determine the number technical executors(timekeepers) R tech. Spanish, according to the formula:

people

Record the results of the calculations in table 16.

Table 5 - Number of employees

1.13 Equipment maintenance and operation costs

The cost of power electricity W forces, kWh, is determined by the formula:

kWh;

1.14 Methods for combating welding deformations

To combat residual deformations and stresses, the following rules should be observed.

When assembling structures, use, if possible, assembly devices (tie bars, wedges, etc.) that ensure free movement of the structures to be welded from shrinkage of the seams. Tacks can only be used for joints of thin metal parts (3-5 mm) and in lap joints. It is necessary to strictly observe the dimensions of blunting, gaps and the alignment of the elements.

Perform the necessary sequence of welding seams; alternating layers of double-sided seam. Do not exceed the amount of heat input into the seam (increase in welding current compared to the recommended for electrodes of the type and diameter used).

Use rigid fastening of parts before welding to reduce their deformations (if provided for by the technological note or instruction) using tacks or fixtures; use the vibration of structures during the welding process to reduce deformations and stresses.

When welding plastic steels and metals, use the forging of the seam layers immediately after welding (if this is provided for in the technological note).

Use pre-bending of sheet metal parts.

When welding sheet tank structures (bottoms and bodies), first weld the joints between the sheets, and then the joints between the strips or belts, in the reverse order, the appearance of cracks at the intersections of the seams, as well as an increase in warping of the structures, is not excluded.

If necessary, apply preliminary and concomitant heating.

Apply, if necessary, general or local heat treatment of welded joints.

Straightening of structures deformed after welding is widely used in factories and workshops in case of unacceptable distortion of the shape and dimensions of structures.

Sometimes a combined thermomechanical method is used to eliminate the bulge. To do this, this bulge is heated to a temperature of 700-800 ° C around the circumference, and then it is evenly tapped with a wooden hammer, placing a plate or some other support on the other side, which will facilitate the plastic deformation of the metal and the elimination of the bulge.

1.15 Choice of quality control methods

Welding consumables must be checked before use:

for the presence of a certificate (for electrodes, wire and flux) with a check of the completeness of the data given in it and their compliance with the requirements of the standard, specifications or passport for specific welding consumables;

for the presence on each packing place (pack, box, box, skein, coil, etc.) of appropriate labels (labels) or tags with verification of the data indicated in them;

for the absence of damage to the packaging and the materials themselves;

for the availability for gas cylinders of the corresponding document regulated by the standard.

Quality control of welded joints of steel structures is carried out:

external inspection with a check of the geometric dimensions and shape of the seams in the amount of 100%;

non-destructive methods (radiography or ultrasonic flaw detection) in the amount of at least 0.5% of the length of the seams. An increase in the scope of control by non-destructive methods or control by other methods is carried out if it is provided for by the drawings of the KM or NTD (PTD).

The results of quality control of welded joints of steel structures must meet the requirements of SNiP 3.03.01-87 (clauses 8.56-8.76), which are given in Appendix 14.

The control of the dimensions of the weld and the determination of the size of the detected defects should be carried out with a measuring tool with a measurement accuracy of ± 0.1 mm, or with special templates for checking the geometric dimensions of the welds. For external examination, it is recommended to use a magnifying glass with a 5-10x magnification.

Cracks of all types and sizes in the seams of welded joints of structures are not allowed and must be eliminated with subsequent welding and inspection.

Inspection of the seams of welded joints of structures by non-destructive methods should be carried out after the correction of unacceptable defects detected by external inspection.

Selective control of the welds of welded joints, the quality of which, according to the project, is required to be checked by non-destructive physical methods, should be subject to areas where defects were detected by external inspection, as well as areas of intersection of the welds. The length of the controlled section is at least 100 mm.

In the welded joints of structures being built or operated in areas with design temperatures below minus 40°C to minus 65°C inclusive, internal defects are allowed, the equivalent area of which does not exceed half of the values of the allowable estimated area. In this case, the smallest search area must be halved. The distance between defects must be at least twice the length of the evaluation section.

In joints accessible for welding from two sides, as well as in joints on linings, the total area of defects (external, internal, or both) in the evaluation area should not exceed 5% of the area of the longitudinal section of the weld in this area.

In joints without backings, available for welding only on one side, the total area of all defects in the evaluation area should not exceed 10% of the area of the longitudinal section of the weld in this area.

Welded joints, controlled at negative ambient temperature, should be dried by heating until the frozen water is completely removed.

1.16 Safety, fire prevention and security environment

Based on the fact that the human body has its own resistance, the safe voltage acting on a person should not exceed 12 V. Therefore, once the open circuit voltage during arc manual welding reaches 80 V, and for plasma cutting and welding 200 V, ensuring safety standards consists in reliable insulation of current-carrying cables and reliable grounding of welding current sources. To avoid electric shock, the equipment must be equipped automatic systems power outage in the event of an arc break. Similarly, the electrode holder must be insulated to prevent accidental contact with workpieces and current-carrying devices. It is strictly forbidden to make contact with the high voltage circuit terminals.

The place where the welding equipment is located must be fenced with a partition made of non-combustible material. Walls are recommended to be painted in matte colors to reduce the effect of light reflection.

When cutting, splashes of molten metal appear, which is a danger to welding equipment. Therefore, it is not allowed to store any lubricants and flammable materials at the location of the equipment. In the event of a fire, it may not be noticed immediately, therefore, upon completion of work, the place of work should be carefully inspected for possible ignition.

During manual arc welding, the atmosphere is polluted mainly by carbon monoxide, nitrogen, hydrogen fluoride, and toxic fluorides. When welding alloyed heat-resistant and high-alloy steels with special properties, chromium, nickel, molybdenum compounds appear in the welding dust, which pollute the atmosphere and settle on the soil.

Calculation of ventilation at workplaces of the assembly and welding section.

Local suctions can be combined with technological equipment and are not hardware related. They can be stationary and non-stationary, mobile and motionless.

The hourly exhaust volume of polluted air L in, is determined by the formula, m 3 / h:

m 3 /h;

We select according to table 17 fan No. 2 with air exchange 1000 m 3 / hour, electric motor 4A100S2U3.

Lighting of the assembly and welding area

In assembly and welding shops, it is advisable to create a general localized or uniform general lighting system using portable local lighting fixtures. Light levels for welding work are set according to normative documents for fluorescent lamps E cf = 150 lux, for incandescent lamps E cf = 50 lux.

The number of lamps L required for lighting is calculated by the formula

A \u003d 12 * 21 \u003d 252 m 2;

PCS.

Conclusion

In this course project, a steel structure farm F1, made of structural heat-resistant, low-alloy steel grade 17GS, is considered. Elements of the welded structure are connected by fillet welds, established in accordance with GOST 5264-80 "Manual arc welding. Welded joints. Main types, structural elements and dimensions." UONI-13/45 electrodes were selected according to GOST 7881-75.

Was chosen RectifierweldingVD-313 which satisfies the basic requirements.

When calculating the amount of equipment and its load, the average load factor was 0.211, which indicates the possibility of increasing the production load and increasing the annual program.

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5. Mikhailov A.I. Welded structures. - M.: Stroyizdzt. 1993. - 366 p.

6. Stepanov B.V. Welder's Handbook. - M.: Higher School, 1990. - 479s.

7. E Belokon V. M - Production of welded structures. - Mogilev. 1998. - 139p.

8. Brauds M.E. Occupational safety during welding in mechanical engineering - M .: Mashinostroenie, 1978. - 186 p.

9. Belov S.V., Brinza V.N. etc. Security production processes: Directory - M .: Mashinostroenie, 1985. - 448 p.

Hosted on Allbest.ru

4. Manufacturability of welded structures

Optimal are the constructive forms that meet the service purpose of the product, ensure reliable operation within the specified resource, allow the product to be manufactured with minimal costs of materials, labor and time.

Manufacturability of the design - the choice of its design, which provides convenience and ease of manufacture of a welded product by any type of welding and under various modes.

The manufacturability of the design is ensured by the choice of metal, the shape of the welded elements and types of joints, types (methods) of welding and measures to reduce welding deformations and stresses.

The manufacturability of a particular design is evaluated qualitatively and quantitatively. A qualitative assessment characterizes manufacturability in a generalized way based on the experience of the performer. It precedes the quantitative assessment and is expressed by a numerical indicator characterizing the degree of satisfaction with the requirements of the manufacturability of the design. The need for a quantitative assessment, the range of indicators and the methodology for their determination are established by industry standards and enterprise standards.

To assess manufacturability, special criteria are used.

The complexity of the construction. The level of manufacturability in terms of the labor intensity of CT is determined by the ratio

where Tp - labor intensity according to the design option, normo-h; Tb - labor intensity according to the basic variant, standard hours.

Material Efficiency. The evaluation of the efficiency of the use of materials can be performed according to the following indicators:

specific material consumption of the structure

material utilization rate

material applicability factor

relative anm or specific Cu m deposited metal consumption

Technical level of welding production determined by the use of progressive mechanized technological processes.

The technical level of production can be assessed by the following indicators:

level of mechanization of welding operations, %:

the level of complex mechanization of work in the manufacture of a welded structure

When choosing a material for welding blanks, it is necessary to take into account not only its operational properties, but also weldability or the possibility of using technological measures that ensure good weldability.

It is usually sought to make welded joints so that they are equal in strength to the base material of the workpiece. In this case, well-welded materials should be chosen: low-alloy steels and alloys, as well as non-ferrous metal alloys.

The strength of the welded joint zone can be increased by subsequent rolling or forging of this zone.

Specifications (T.U.) for the product

The main requirement for the product is to ensure the reliability of operation under operating conditions.

Assembly and welding operations must be carried out in accordance with the attached drawings to the technological sheet. Types of welded joints and accuracy tolerances of their assembly must comply with GOST 8713-79. “Submerged arc welding. Welded connections.

Specifications for base and welding consumables

Incoming stamped parts should not have dents, delaminations, pores and various contaminants. Workpieces must be degreased before welding.

The surface of the wire must be clean and smooth, without cracks, delaminations, captivity, sunsets, shells, nicks, scale, rust, oil and other contaminants. On the surface of the wire, risks (including tightened ones), scratches, local ripples and individual dents are allowed. The depth of these flaws should not exceed the maximum deviation in wire diameter.

Flux specifications

AN-348A was chosen as a protective flux. Supplied in accordance with GOST 9087-81.

Fluxes should be produced in the form of uniform grains. The content of foreign particles (undissolved particles of raw materials, lining, coal, graphite, coke, metal particles, etc.) should not exceed: 0.5% of the mass of the flux.

Working with fluxes during their sorting, packaging, transportation, quality control may be accompanied by the release of dust containing manganese, siliceous, fluorine compounds. Flux dust is chemically hazardous and harmful. production factors. By the nature of the impact on the human body, flux dust is toxic, irritating and sensitizing, the ways of penetration into the body are through the respiratory system, skin and mucous membranes.

Fluxes are accepted in batches. The batch should consist of a flux of the same brand and be issued with one quality document containing:

Trademark or name and trademark of the manufacturer;

Flux brand

lot number;

the mass of the party;

· results chemical analysis;

the date of manufacture;

the designation of this standard.

The mass of the batch should not exceed 80 tons.

The selected sample is thoroughly mixed, after which it is quartered to a mass of at least 2.5 kg, of which 0.5 kg is taken after mixing to determine the chemical composition and humidity. The remaining flux is quartered, receiving four portions - each weighing at least 0.5 kg, of which two portions are taken for two parallel determinations of bulk density, the third portion is divided in half, obtaining two portions of 250 g each to determine the particle size distribution, and from the last portion after quartering select two portions of 100 g to control uniformity.

The granulometric composition of the fluxes is determined by sieving the sample on a 029M brand device, manufactured according to the normative and technical documentation, through the corresponding two sieves with a diameter of 200 mm for (60 ± 5) s, and then weighing the residue on a coarse sieve and sifting under a fine sieve with an error of not more than 0 ,one %.

Each bag or container shall be labeled or marked with waterproof paint indicating:

trademark or name and trademark of the manufacturer;

Flux brand

net weight;

lot number;

the designation of this standard;

Handling sign “Keep away from moisture”.

The flux must be transported in covered vehicles by any mode of transport in accordance with the rules for the transportation, loading and securing of goods in force for the corresponding mode of transport.

assembly specifications

Assembly is one of the most critical operations; the quality of the welded structure depends on its quality.

Therefore, the following requirements are imposed on the details:

a) After preparing the edges, the parts must have a surface free of pores, pits, nicks, burrs, scratches and dents.

b) The preparation of the edges of the workpieces should ensure the possibility of a thorough joining of the latter for welding along the entire length of the seam with a minimum gap.

c) The permissible and regulated gap in the joint should not exceed the tolerances indicated on the drawing (see graph. part).

e) Assembly and welding fixtures must ensure the accuracy of assembly of products for welding and reliable clamping of the edges to be welded.

Specifications for welding

Welding of metal structures is carried out in accordance with the technological process.

Welding should be carried out after assembly quality control.

When welding and tacking, it is necessary to protect the front side of the seam from interaction with the atmosphere.

The edges to be welded and the surface of the parts at a distance of (10-15) mm from the edges should not have traces of fusible metals and compounds, such as copper.

The use of cooling and clamping equipment in welding improves the structure of the metal, the mechanical and corrosion properties of the joint. Before welding, degrease the weld area at a distance of 45 mm with a napkin (GOST 11680-76) moistened with acetone (GOST 2768-69), as well as a spacer, lead plates, copper surfaces of the linings, upper and adjacent surfaces. Check the gaps in the joint no more than 0.2 mm. The spacer must be tacked at 4 points and the lead plates along the entire height with the help of ArDES and then check the quality of the tacks. Cleaning of places of tacks of spacers is carried out with a metal brush to a metallic sheen and degreasing with a cloth moistened with acetone. Before welding, it is necessary to apply the risk of the axis welding seam on the outlet plates, adjust the gas flow and wait 20-30 seconds until the air is completely removed from the system. Pre-test welding modes on technological samples (1 technological sample per batch of parts of the same thickness, welded during the first, second shift). Welding is performed by 2 people: a locksmith and a welder. Welding is carried out in a stable mode, established by the technological process with an allowable fluctuation in the voltage of the electric current supply network not exceeding ± 5% of the nominal. After the weld has cooled (until the weld darkens), turn off the argon, after which the welded parts are kept in a fixed state for at least 15 minutes.

To control the quality of the welded seam, a witness sample is welded for a batch of parts (but not more than 5 machines of the same thickness, welded during the first, second shift). Welding of parts of witness samples is carried out without readjustment of GSPD-1M.

Welders who have passed certification in accordance with the rules established by Gosgortekhnadzor should be allowed to perform welding work.

Welding work must be carried out with the provision of safety requirements.

Material Description

For the sorption column, steel 09G2S is used; this steel is manufactured in accordance with GOST 5520-79. Table 1 shows the chemical composition of steel 09G2S.

Table 1 - Chemical composition of steel 09G2S

Most often, rolled products from this steel grade are used for a variety of building structures due to their high mechanical strength, which allows the use of thinner elements than when using other steels. The stability of properties in a wide temperature range allows the use of parts from this brand in the temperature range from -70 to +450 C. Also, easy weldability makes it possible to manufacture complex structures from sheet metal of this brand for the chemical, oil, construction, shipbuilding and other industries. Using hardening and tempering, high-quality pipeline fittings are made. High mechanical resistance to low temperatures also makes it possible to successfully use pipes made of 09G2S in the north of the country.

The brand is also widely used for welded structures. Welding can be carried out both without heating and with preheating up to 100-120 C. Since there is little carbon in steel, its welding is quite simple, and the steel does not harden and does not overheat during the welding process, due to which there is no decrease in plastic properties or increase in grain size. The advantages of using this steel can also be attributed to the fact that it is not prone to temper brittleness and its toughness does not decrease after tempering. The above properties explain the convenience of using 09G2S from other steels with a high carbon content or additives that cook worse and change properties after heat treatment. For welding 09G2S, you can use any electrodes designed for low-alloy and low-carbon steels, for example, E42A and E50A. If sheets up to 40 mm thick are welded, then welding is carried out without cutting edges. When using multilayer welding, cascade welding is used with a current of 40-50 A per 1 mm of electrode to prevent overheating of the welding site. After welding, it is recommended to heat the product to 650 C, then keep it at the same temperature for 1 hour for every 25 mm of rolled product thickness, after which the product is cooled in air or in hot water - due to this, the weld hardness increases in the welded product and tension zones are eliminated.

For submerged arc welding of 09G2S steel when operating at temperatures below -40 °C, it is recommended to use Sv-08GA welding wire. Flux of the AN-348A brand is used as fluxes in single-arc welding.

Technical part

MINISTRY OF EDUCATION OF THE REPUBLIC OF BELARUS

BOBRUYSK STATE MACHINE-BUILDING

VOCATIONAL AND TECHNICAL COLLEGE

Specialty 2-36 01 06 Equipment and

welding production technology

Specialization 2-36 01 06 02 Production of welded

structures

Qualification technician-technologist

AGREED I APPROVE

cycle commission of special disciplines Deputy. director of management

Protocol No. __ dated "__" _________ 20__ ________ Metelitsa S.I.

Chairman of the Central Committee ______ "__" ___________ 20__

METHODOLOGICAL INSTRUCTIONS

for the implementation

graduation project

Developed by teachers disciplines

N.M. Rogomantseva

K.D. Yukhnevich

engineering graphics teacher

YES. Melnikovi.

General provisions, composition and content of the course project 4

Introduction 5

1 Technology section 6

1.1 Description of the welded structure, its purpose 6

1.2 Weldment material justification 6

1.3 Specification for the manufacture of a welded structure 7

1.4 Determining the type of production 11

1.5 Selection and justification of assembly and welding methods 12

1.6 Welding modes 15

1.7 Selection of welding consumables 20

1.8 Selection of welding equipment, technological equipment,

tool 21

1.9 Determination of technical norms of assembly and welding time 22

1.10 Calculation of the amount of deposited metal, consumption of welding

materials, electricity 25

1.11 Calculation of the amount of equipment and its load 28

1.12 Calculation of the number of employees 30

1.13 Equipment maintenance and operation costs 32

1.14 Methods for combating welding deformations 33

1.15 Selecting quality control methods 33

2 Design section 34

2.1 Description of the construction of the column 34

2.2 Selection and justification of weld metal 34

2.3 Calculation and design of the column bar 34

2.4 Calculation and design of connecting strips 36

2.5 Calculation of welds attaching planks to column branches 38

2.6 Calculation and design of the column base 39

2.7 Calculation and design of the column head and its joints 42

2.8 Selection of welding method and methods of quality control of welded

compounds 43

2.9 Selection of welding modes and welding equipment 43

3 Occupational safety section 45

3.1 Calculation of ventilation at the workplaces of the assembly and welding

plot 45

3.2 Lighting of the assembly and welding area 47

4 Economic section 49

4.1 Calculation of material costs 49

4.2 Calculation of wages of production workers, deductions and

tax from her 50

4.3 Calculation of the total cost of the product 53

4.4 Comparison of manufacturing process options

Conclusion 59

List of sources used 60

Standards 62

Appendix A. Weldment specification

Appendix B. Specification for assembly tool and tacks

GENERAL PROVISIONS, COMPOSITION AND CONTENT

THE DIPLOMA PROJECT

A diploma project is a complex independent creative work performed at the final stage of education, during which the student solves specific professional tasks corresponding to the level of education of the qualification being awarded, on the basis of which the State Qualification Commission decides on awarding the student a specialist qualification.

The completed graduation project consists of an explanatory note of 50-70 pages of handwritten or 20-40 pages of typewritten text. The graphic part is done on 4 sheets of drawing paper.

The topics of graduation projects should reflect the specific tasks facing domestic machine-building enterprises. It should provide for the design of the technological process of assembly and welding of a given welded structure at a certain volume of its production per year. The technological process must meet the current level of the relevant industry.

When using factory-made basic, welding and auxiliary materials, a new version of the technological process should be more progressive, provide higher labor productivity, reduce the technological cost of manufacturing welded structures, and improve their quality.

The topic of graduation projects should be considered at a meeting of the cyclic commission and approved by the deputy director for academic work.

Responsibility for making a decision in the graduation project, the quality of the explanatory note, the graphic part, a set of documents for the technological process, as well as for the timely completion of the work, is the responsibility of the author-student and supervisor.

INTRODUCTION

In the introduction, it is required to briefly state the data on the development of welding and the use of welded structures, what high-performance methods of assembly and welding of welded structures are used in the Republic of Belarus and abroad at the present stage.

1 TECHNOLOGICAL SECTION

1.1 Description of the welded structure, its purpose

Describe the purpose of the welded structure, its operating conditions, design, methods for preparing parts to be welded, study the literature:,, and indicate whether this structure meets the requirements for technological welded structures. Give the overall dimensions and weight of the welded structure.

1.2 Justification of the material of the welded structure

Justification of the material of the welded structure should be carried out taking into account the following basic requirements:

Ensuring strength and rigidity at the lowest cost of its manufacture, taking into account the maximum savings in metal;

Guaranteeing conditions for good weldability with minimal softening and reduced plasticity in the zones of welded joints;

Ensuring the reliability of operation of the structure under given loads, at variable temperatures in aggressive environments.

Indicate the mechanical properties and chemical composition of the welded material.

To study the literature and establish the weldability of the steel grade in terms of carbon equivalent C e, from the formula

where C e is the carbon equivalent, %;

Carbon content, %;

Magnesium content, %;

Nickel content, %;

Chromium content, %;

Molybdenum content, %;

Vanadium content, %.

Steels with C e = 0.2 ... 0.45% are well welded, do not require preheating and subsequent heat treatment.

Table 1.1 - Chemical composition of steels

End of table 1.1

Table 1.2 - Mechanical properties of steels

Tensile strength, MPa	Yield strength, MPa	Relative extension, %	Impact strength, J / cm 2
			at test t, °С

1.3 Specifications for the manufacture of a welded structure

Specifications for the manufacture of a welded structure provide for specifications for basic materials, welding consumables, as well as requirements for workpieces for assembly and welding, for welding and for welding quality control.

Students should take the technical conditions for the manufacture of welded structures at the factories in the OGS or at the assembly and welding bureau, where they undergo technological practice.

1.3.1 As the main materials used for the manufacture of critical welded structures (supervised by GOSPROMATOMNADZOR) operating under dynamic loads, alloy steels according to GOST 19281-89 or ordinary carbon steels of at least grade St3ps according to GOST 380-94 should be used. For non-critical welded structures, steels of at least grade St3ps according to GOST 380-94 should be used.

1.3.2 Compliance of all welding consumables with the requirements of the standards must be confirmed by the certificate of the supplying plants, and in the absence of a certificate, by the test data of the plant's laboratories.

In manual arc welding, electrodes of at least type E42A in accordance with GOST 9467-75 with a rod made of Sv-08 wire in accordance with GOST 2246-70 should be used.

When welding in carbon dioxide, a wire of at least Sv-08G2S in accordance with GOST 2246-70 should be used.

Welding wire must be free of rust, oil and other contaminants.

1.3.3 The requirements for blanks for welding provide that the parts to be welded from sheet, shaped, sectional and other rolled products must be straightened before assembly for welding.

After rolling or bending, the parts must not have cracks and burrs, tears, waviness and other defects.

The edges of parts cut with scissors should not have cracks or burrs. The cut edge must be perpendicular to the surface of the part. The allowable slope in cases not specified in the drawings should be 1:10, but not more than 2 mm.

The need for machining the edges of parts should be indicated in the drawings and technological processes.

Dents after straightening and curvilinearity of welded edges should not go beyond the established tolerances for gaps between welded parts. Limit deviations of angular dimensions, if they are not specified in the drawings, must correspond to the tenth degree of accuracy of GOST 8908-81.

Parts supplied for welding must be accepted by the Quality Control Department.

1.3.4 The assembly of the parts to be welded must ensure the presence of a specified gap within the tolerance along the entire length of the joint. The edges and surfaces of parts at the locations of welds to a width of 25-30 mm must be cleaned of rust, oil and other contaminants immediately before assembly for welding.

Parts intended for contact welding at the joints must be cleaned from both sides of scale, oil, rust and other contaminants.

Parts with cracks and tears formed during manufacture are not allowed to be assembled for welding.

These requirements are provided with technological equipment and appropriate tolerances for assembled parts.

When assembling, force adjustment is not allowed, causing additional stresses in the metal.

The allowable displacement of the welded edges relative to each other and the size of the allowable gaps should not exceed the values established for the main types, structural elements and dimensions of welded joints in accordance with GOST 14771-76, GOST 23518-79, GOST 5264-80, GOST 11534-75, GOST 14776-79, GOST 15878-79, GOST 8713-79, GOST 11533-75.

Local increased clearances must be eliminated before assembly for welding. It is allowed to weld gaps by surfacing the edges of the part, but not more than 5% of the weld length. It is forbidden to fill the enlarged gaps with pieces of metal and other materials.

The assembly for welding must ensure the linear dimensions of the finished assembly unit within the tolerances specified in Table 1.3.

Table 1.3 - Limit deviations of welded assembly units

The cross section of tacks is allowed up to half the cross section of the weld. Tacks should be placed at the locations of the welds. The applied tacks must be cleaned of slag.

Tacking of welded structures during assembly must be carried out using the same filler materials and requirements as when making welds.

The dimensions of the tacks must be indicated in the process charts.

Assembly for welding must be accepted by the quality control department. During transportation and tilting of metal structures assembled for welding, measures must be taken to ensure the preservation of the geometric shapes and dimensions specified during assembly.

1.3.5 Only certified welders with a certificate establishing their qualifications and the nature of the work to which they are authorized should be allowed to weld critical assembly units.

Welding equipment must be provided with voltmeters, ammeters and pressure gauges, except in cases where the installation of devices is not provided. The condition of the equipment must be checked daily by the welder and fitter.

Preventive inspection of welding equipment by the department of the chief mechanic and power engineer should be carried out at least once a month.

The manufacture of steel welded structures should be carried out in accordance with the drawings and the assembly and welding process developed on their basis.

The technological process of welding should provide for such an order of suturing in which internal stresses and deformations in the welded joint will be the smallest. It should provide maximum possibility of welding in the lower position.

It is prohibited to carry out welding work by methods not specified in the technological process and this standard without the consent of the chief specialist in welding. Deviation from the welding modes specified in the process charts, the sequence of welding operations is not allowed.

The surfaces of the parts at the location of the welds must be checked before welding. Edges to be welded must be dry. Traces of corrosion, dirt, oil and other contaminants are not allowed.

It is forbidden to strike an arc on the base metal, outside the boundaries of the seam, and to bring the crater to the base metal.

Dimensional deviation cross section welds indicated in the drawings, when welding in carbon dioxide, must be in accordance with GOST 14771-76.

In appearance, the weld should have a uniform surface without sagging and sagging with a smooth transition to the base metal.

At the end of welding, before the product is presented to the quality control department, welds and surfaces adjacent to them must be cleaned of slag, sagging, metal spatter, scale and checked by the welder.

In contact spot welding, the depth of electrode indentation into the base metal of the welding point should not exceed 20% of the thickness of the thin part, but not more than 0.4 mm.

The increase in the diameter of the contact surface of the electrode during welding should not exceed 10% of the size established by the technical process.

When assembling for spot welding, the gap between the contacting surfaces at the locations of the points should not exceed 0.5 ... 0.8 mm.

When welding stamped parts, the gap should not exceed 0.2 ... 0.3 mm.

When spot welding parts of different thicknesses, the welding mode should be set in accordance with the thickness of the thinner part.

After assembling the parts for welding, it is necessary to check the gaps between the parts. The size of the gaps must comply with GOST 14771-76.

The dimensions of the weld must comply with the drawing of the welded structure in accordance with GOST 14776-79.

1.3.6 In the process of assembly and welding of critical welded structures, step-by-step control shall be carried out at all stages of their manufacture. The percentage of parameter control is specified by the technological process.

Before welding, check the correct assembly, the dimensions and quality of the tacks, compliance with the geometric dimensions of the product, as well as the cleanliness of the surface of the welded edges, the absence of corrosion, burrs, dents, and other defects.

During the welding process, the sequence of operations established by the technical process, individual seams and the welding mode should be controlled.

After completion of welding, quality control of welded joints should be carried out by external inspection and measurements.

Fillet welds are allowed convex and concave, but in all cases, the leg of the seam should be considered the leg of an isosceles triangle inscribed in the section of the weld.

Inspection can be carried out without the use of a magnifying glass or using it with an increase of up to 10 times.

The control of the dimensions of welds, points and detected defects should be carried out with a measuring tool with a division value of 0.1 or special templates.

Correction of the defective section of the weld more than twice is not allowed.

External inspection and measurement of welded joints should be carried out in accordance with GOST 3242-79.

1.4 Determining the type of production

All machine-building enterprises, workshops and sections can be assigned to one of three types of production:

Single;

Serial;

Mass.

Single production is characterized by a wide range of manufactured products and a small volume of their output. It is distinguished by the versatility of equipment and workplaces. In the welding industry, there is almost no special welding equipment, assembly and welding fixtures and mechanisms.

Serial production is characterized by a limited range of manufactured products and a large volume of output, repeated after a certain period of time in batches.

The technological process in serial production is differentiated, i.e. divided into separate operations, which are assigned to separate jobs. A relatively stable product range makes it possible to widely use special assembly and welding fixtures, introduce automated welding methods, and organize production lines in some areas. In this case, both general workshop transport and floor transport are used. Specialization certain types work requires highly skilled workers.

In mass production, technological processes are developed in more detail, indicating the modes of operation, methods of control.

Serial production is much more efficient than single production. equipment is used more fully, and the specialization of jobs ensures labor productivity. Depending on the number of products in a batch and the value of the coefficient of consolidation of operations, small-scale, medium-scale and large-scale production is distinguished.

Mass production is characterized by the continuous production of a narrow range of products for a long time and a large volume of output. It allows the wide use of special high-performance equipment and devices. This ensures high labor productivity, better use of the main production assets and lower cost of production than in serial and single production.

Based on the mass and dimensions of the welded structure, as well as the given production program, taking into account the characteristics of each type of production, one or another type of production is selected - table 1.4.

Table 1.4 - Dependence of the type of production on the release program (pcs) and the mass of the product

Part weight, kg	single production	Small-scale production	Medium batch production	Large batch production	Mass production

1.5 Selection and justification of assembly methods and welding

1.5.1 Assembly of welded structures in single and small-scale production can be carried out by marking using the simplest universal devices (clamps, staples with wedges), followed by tacking using the same welding method as when making welds.

Under the conditions of serial and mass production, assembly for welding should be carried out on special assembly stands or in special assembly and welding fixtures that provide the required relative position of the parts included in the welded structure and the assembly accuracy of the welded structure being manufactured in accordance with the requirements of the drawing and assembly specifications.

In addition, assembly fixtures reduce the assembly time and increase labor productivity, facilitate working conditions, increase the accuracy of work and improve the quality of the finished welded structure.

The parts assembled for welding are fastened in fixtures and on stands using various types of screw, manual, pneumatic and other clamps.

1.5.2 The choice of one or another welding method depends on the following factors:

Thickness of the material to be welded;

The length of the welds;

Requirements for the quality of products;

The chemical composition of the metal;

expected performance;

Cost of 1 kg of deposited metal;

Among the methods of electric arc welding, the most used are.

Manual arc welding;

Mechanical welding in shielding gases;

Automated welding in shielding gases and submerged arc.

Due to low productivity and high labor intensity, manual arc welding (MAW) is unacceptable in serial and mass production. It is mainly used in single production.

The most expedient is the use of mechanized welding methods.

One of these methods is semi-automatic welding in carbon dioxide, which currently occupies a significant place in the national economy due to its technological and economic advantages.

Technological advantages are the relative simplicity of the welding process, the possibility of semi-automatic and automatic welding of seams located in various spatial positions, which makes it possible to mechanize welding in various spatial positions, including welding of fixed pipe joints.

A small amount of slag involved in the welding process in CO 2 allows in some cases to obtain high quality seams

The economic effect of the use of welding in carbon dioxide significantly depends on the thickness of the metal being welded, the type of joint, the location of the seam in space, the diameter of the electrode wire and welding modes.

The cost of 1 kg of deposited metal in carbon dioxide welding is always lower than in gas and manual arc welding.

When welding in carbon dioxide with a wire with a diameter of 0.8-1.4 mm of steel products, up to 40 mm thick in all positions, the output in medium modes on automatic machines is 2-5 times higher, and on semi-automatic devices - 1.8-3 times higher than in manual arc welding.

When welding in carbon dioxide with a wire with a diameter of 0.8-1.4 mm of vertical and ceiling seams made of steel with a thickness of 8 mm or more and in the lower position with a thickness of more than 10 mm with wires with a diameter of 1.4-2.5 mm, the productivity is 1.5- 2.5 times higher than manual arc welding.

The productivity of welding in carbon dioxide with wires with a diameter of 1.4-2.5 mm from steel with a thickness of 5-10 mm in the lower position depends on the nature of the product, the type and size of the connection, the quality of the assembly, etc. At the same time, the productivity is only 1.1-1 .8 times higher than manually.

The listed technological and economic advantages of welding in carbon dioxide make it possible to widely use this method in serial and mass production.

To perform long seams on metal of medium and large thickness, it is advisable to use automatic submerged arc welding. In submerged arc welding, the stick out of the electrode is much less than in manual arc welding. Therefore, it is possible, without fear of overheating of the electrode and separation of the protective coating, to increase the strength of the welding current several times, which allows a sharp increase in welding productivity, which is 5-20 times higher than in manual arc welding, the deposition coefficient reaches 14-16 g/Ah in some cases even 25-30 g/Ah.

The melting of the electrode and base metal occurs under a flux that reliably isolates them from the environment. The flux contributes to the production of clean and dense weld metal, without pores and slag inclusions, with high mechanical properties. The introduction of stabilizer elements into the flux and the high current density in the electrode makes it possible to weld metal of considerable thickness without cutting edges. There are practically no losses due to waste and spattering of the electrode metal. The welding process is almost completely mechanized. Compared to RDS, mechanized submerged arc welding significantly improves the working conditions of the welder-operator, increases the overall level and culture of production,.

Currently on machine-building enterprises In the Republic of Belarus, work is increasingly being carried out to introduce welding in argon mixed with carbon dioxide into production. When welding in CO 2 with wires of any diameter, two types of molten metal transfer are revealed, characteristic of optimal modes: with periodic short circuits of the arc gap and drip transfer without short circuits. When welding in a mixture of Ar + CQ 2, the region of welding modes with short circuits of the arc gap is absent. The change in the nature of the transfer when replacing the protective medium can be considered as an improvement in the technological process, especially since it is accompanied by an improvement in the qualitative and quantitative characteristics of the welding process: spattering and spraying of metal onto the welding part and nozzle.

When welding in carbon dioxide at optimal conditions, approximately 1 g / Ah of spatter is sprayed onto the parts. Spatter sticks to the surface of the metal to be welded and is hardly removed with a metal brush. 25-30% of large drops are welded to the metal, and work with a chisel or other means of cleaning the seam is necessary to remove them. A significant reduction in spatter on parts is observed when welding in an Ar + CO 2 mixture by at least 3 times.

When welding in CO 2, there is a region of regimes in which an increase in nozzle spatter is observed. For a wire with a diameter of 1.2 mm, this region is 240-270 A, and for a wire diameter of 1.6 mm - 290-310 A. When welding in a mixture of argon and carbon dioxide, the region of large spatter modes is practically absent. Splashing of the nozzle deteriorates the condition of the gas shield, and periodic cleaning reduces productivity. The shape of penetration during CO 2 welding is rounded and is retained in the Ar + CO 2 mixture at low currents. At high currents, a protrusion appears in the lower part of the penetration, which increases the depth of penetration, which increases the area of destruction along the fusion zone. With an equal penetration depth, the penetration area of the base metal in the Ar+CO 2 mixture is 8-25% less than in CO 2 welding, which leads to a decrease in deformation. Along with welding in a mixture of argon with carbon dioxide, welding in a mixture of carbon dioxide with oxygen has received the widest application. The presence of oxygen in the mixture within the range of 20-30% reduces the surface tension forces, which contributes to a finer droplet transfer and a more "resistant" gap between the droplet and the electrode, which reduces spatter. In addition, the oxidized drop is worse welded to the metal. Oxidized reactions increase the amount of heat generated in the arc zone, which improves welding performance. Welding in a mixture of CO 2 + O 2 has the greatest advantages with an increased electrode stick-out and the use of zirconium-alloyed wires, for example, Sv08G2STs.

Semi-automatic welding in a mixture of CO 2 +O 2 is carried out with wires with a diameter of 1.2-1.6 mm, wires of the brands Sv08G2S and Sv08G2STs with the usual electrode stick out in all spatial positions.

1.6 Welding modes

1.6.1 The main parameters of automatic and semi-automatic submerged arc welding are: welding current, diameter, welding speed.

The calculation of the welding mode is always made for a specific case when the type of joint, the thickness of the metal being welded, the wire grade, the flux and the method of protection against the flow of molten metal into the joint gap are known. Therefore, before starting the calculation, it is necessary to establish the structural elements of a given welded joint in accordance with GOST 8713-79. In this case, it must be taken into account that the maximum cross section of a single-pass weld made by an automatic machine should not exceed 100 mm 2.

For butt joints, the cross-sectional area of the weld Ash, mm 2 is determined by the formula

Ash = 0.75eg + sb, (1.2)

where Ash is the cross-sectional area of the weld, mm 2;

e - seam width, mm;

g - reinforcement of the seam, mm;

s - thickness of the seam, mm;

b - gap, mm.

The strength of the welding current I, A, is determined by the depth of penetration from the formula

I = (80...100)h, (1.3)

where I is the strength of the welding current, A;

h - penetration depth, mm.

The penetration depth is set constructively, based on the thickness of the metal.

For a single-pass butt weld, the penetration depth h, mm, is selected from the condition

h = (0.7...0.8)S, (1.4)

where h is the penetration depth, mm;

For double-sided welding, the penetration depth h, mm, is selected from the condition

, (1.5)

where h is the penetration depth, mm;

S is the thickness of the welded metal, mm.

and should be at least 60% of the thickness of the parts to be welded.

The diameter of the welding wire d, mm, is taken depending on the thickness of the metal being welded within 2 ... 6 mm, and then refined by calculation

where d is the diameter of the welding wire, mm;

I - welding current, A;

i - current density, A / mm 2

The current density depending on the wire diameter is shown in Table 1.5.

Table 1.5 - Current density depending on the diameter of the wire.

Arc voltage U, V is taken within 32-40 V.

Welding speed V sv, m/h, is determined by the formula

, (1.7)

where V sv - welding speed, m/h;

Surfacing coefficient, g/Ah;

I - welding current, A;

Ash - cross-sectional area, mm 2;

γ - specific density of the deposited metal, g/cm 3 .

When welding with direct current of reverse polarity, the deposition coefficient , is calculated by the empirical formula

11.6 ± 0.4 g/Ah (1.8)

When welding on direct current of direct polarity and alternating current deposition coefficient , determined by the formula

, (1.9)

where - deposition coefficient, g/Ah;

A and B are coefficients, the values of which for the AN-384A flux are given in Table 1.6.

Table 1.6 - The values of the coefficients A and B for the flux AN-384A

Wire feed speed Vpod, m/h, determined by the formula

, (1.10)

where Vpod - wire feed speed, m/h;

Ash - cross-sectional area of the seam, mm 2;

Ae - the area of seeding of the electrode wire, mm 2;

Vsv - welding speed, m/h.

The feed rate of the electrode wire V under, m/h, can also be calculated as follows, according to the formula

, (1.11)

where V under - electrode wire feed speed, m/h

αn - deposition coefficient, g/Ah;

I - welding current, A;

d - welding wire diameter, mm;

γ - specific density of the deposited metal, g/cm 3 .

1.6.2 Calculation of modes of automatic and semi-automatic submerged arc welding of fillet welds.

Determine the cross-sectional area Ash, mm, according to the leg of the seam specified in the drawings, according to the formula

, (1.12)

where Ash - cross-sectional area, mm

According to GOST 14771-76, reinforcement of the fillet weld q, mm, made in the lower position, is allowed up to 30% of its leg, i.e.

where q is the height of the reinforcement of the seam, mm;

k - leg of the seam, mm.

We set the number of passes based on the fact that no more than 100 mm 2 of the weld area can be welded with an automatic machine in one pass.

We select the diameter of the electrode, bearing in mind that fillet welds with a leg of 3-4 mm can be obtained using an electrode wire with a diameter of 2 mm, when welding with an electrode wire with a diameter of 4-5 mm, the minimum leg is 5-6 mm. Welding wire with a diameter of more than 5 mm should not be used, because. it does not provide root penetration.

For the accepted wire diameter, we select the current density according to the data given in Table 1.5, and determine the strength of the welding current I, A, according to the formula

, (1.14)

where I sv - the strength of the welding current, A;

d is the diameter of the welding wire, mm;

i - current density, A / mm 2.

Determine the deposition coefficient according to one of the previously given (1.8) and (1.9) formulas, depending on the type of current and polarity.

Knowing the area of surfacing in one pass, the welding current and the surfacing coefficient, determine the welding speed V CB, m/h using the formula (1.7).

The electrode wire feed rate is determined by formula (1.10).

1.6.3 The choice of welding mode in carbon dioxide, as well as in a mixture of gases, is made depending on the thickness and properties of the metal being welded, the type of welded joint and the position of the weld in space based on generalized experimental data.

1.7 Selection of welding consumables

The general principles for the selection of welding consumables are characterized by the following main conditions:

Ensuring the required operational strength of the welded joint, i.e. determined level of mechanical properties of the weld metal in combination with the base metal;

Ensuring the necessary continuity of the weld metal (without pores and slag inclusions or with the minimum size and number of these defects per unit length of the weld);

The absence of hot cracks, i.e. obtaining weld metal with sufficient technological strength;

Obtaining a complex of special properties of metal, weld (heat resistance, heat resistance, corrosion resistance).

The choice of welding consumables is made in accordance with the accepted method of welding.

The choice and justification of specific types and grades of welding consumables should be made on the basis of literary sources, taking into account the requirements.

In the technological process maps for each technological operation (tack assembly, welding), it is necessary to indicate the types, grades, standard for types and grades of welding consumables.

In manual arc welding of structural carbon and alloy steels, the choice of electrodes is made in accordance with GOST 9467-75, which provides for two classes of electrodes. The first class is electrodes for welding carbon and alloy steels, the requirements for which are established by the mechanical properties of the deposited metal and the content of sulfur and phosphorus in it. The second class regulates the requirements for electrodes for welding alloyed heat-resistant steels and which are classified according to chemical properties deposited weld metal.

GOST 10052-75 establishes requirements for electrodes for welding high-alloy steels with special properties. The choice of electrodes for welding these steels is made according to this GOST.

The choice of steel wire for mechanized welding methods is made in accordance with GOST 2246-70, which provides for the production of steel welding wire for welding with a diameter of 0.3 to 12 mm.

Welding wire for welding aluminum and its alloys is supplied in accordance with GOST 7881-75.

The choice of fluxes for welding is made in accordance with GOST 9078-81, which provides for two groups of fluxes:

For welding carbon low and medium alloy steels (AN-348A, AN-348AM, OSC-45, AN-60, AN-22, FTs-9, AN-64);

- for welding high-alloy steels (AN-26, AN-22, AN-30, ANF-14, ANF-16, ANF-17, FCC-S, K-8).

Inert gases (argon, helium) and active gases (carbon dioxide, hydrogen) are used as protective gases during welding.

Argon intended for welding is regulated by GOST 10157-79 and, depending on the percentage of argon and the purpose, is divided into argon of the highest, first and second grade.

Helium is supplied in accordance with GOST 20461-75, which provides for two grades of gaseous helium: high purity helium (99.98% He) and technical helium (99.8% He).

Carbon dioxide intended for welding corresponds to GOST 8050-85, which, depending on the CO 2 content, provides for two grades of welding carbon dioxide: the first grade - with a CQ 2 content of at least 99.5%, the second grade - with a CO 2 content of at least 99%.

After substantiating the choice of welding consumables for the welding methods adopted in the project, it is necessary to tabulate the chemical composition of these materials, the mechanical properties and the chemical composition of the deposited metal.

1.8 Selection of welding equipment, technological equipment,

tool

In accordance with the established technological process, the welding equipment is selected. The main selection conditions are:

Technical characteristics of welding equipment that meets the accepted technology;

The smallest dimensions and weight;

The highest efficiency and the lowest power consumption;

Minimum cost.

The main condition when choosing welding equipment is the type of production.

So, for single and small-scale production, for economic reasons, cheaper welding equipment is needed - welding transformers, rectifiers or semi-automatic welding machines, giving preference to equipment operating in a shielding gas environment with a power source - rectifiers.

For selection rational types equipment, you should use the latest data from reference and information literature, catalogs and brochures on welding technology, which contain the technical characteristics of power sources, semi-automatic welding machines and automatic machines.

When determining the consumption of electricity, conduct its consumption according to the power of the power source and add 0.3 ... 0.5 kW to it for the control circuit of the machine, semi-automatic.

The selection and design of assembly and welding fixtures (equipment) is carried out in accordance with pre-selected methods of assembling and welding units. When developing this issue it must be taken into account that the choice of assembly and welding fixtures should provide the following:

Reducing the labor intensity of work, increasing labor productivity, keeping the duration production cycle;

Facilitation of working conditions;

Increasing the accuracy of work, improving the quality of products, maintaining the desired shape of the welded products by appropriately fixing them to reduce deformations during welding.

Devices must meet the following requirements:

Ensure accessibility to the places of installation of parts to the handles of clamping and fixing devices, to places of sticking and welding;

Ensure the most advantageous assembly order;

Must be strong and rigid enough to ensure accurate fixing of parts in the required position and prevent their deformation during welding;

To provide such positions of products at which there would be the least number of turns, both when applying tacks, and when welding;

Provide free access when checking the product;

Ensure safe assembly and welding operations.

In serial production, fixtures should be selected based on the possibility of restructuring production for the new kind products, i.e. universal.

The type of fixture must be selected depending on the program, product design, technology and degree of accuracy in the manufacture of blanks, assembly-welding technology.

The working and measuring tool is selected specifically for each assembly and welding operation, based on the requirements of the drawing and technical specifications for the manufacture of the welded structure.

1.9 Determination of technical standards for assembly and welding times

The total time to perform the welding operation Tw, hour, consists of several components and is determined by the formula:

Tsv \u003d tо + tp.z. + tv + tobs + tp, (1.15)

where Tsv - total time to perform a welding operation, hour;

tp.z. - preparatory and final time;

to - main time;

t in - auxiliary time;

t obs - time to service the workplace;

t p - the time of breaks for rest and personal needs.

The main time is the time for the actual execution of the welding operation. It is determined by the formula:

where is the main time, hour;

Surfacing coefficient, g/A hour;

I sv - the strength of the welding current, A;

Weight of deposited metal, g

The sum of the lengths of all seams, see

The calculated basic welding time can be checked using the formula:

where is the main time, hour;

The sum of the lengths of all seams, cm;

Seam welding speed, cm/hour.

The preparatory and final time includes such operations as receiving a production task, briefing, receiving and handing over a tool, inspecting and preparing equipment for work, etc. When determining it, the general standard of time t p.z. divided by the number of parts produced per shift. IN term paper let's accept:

t p.z. \u003d 10% of t about.

Auxiliary time includes the time for filling the cassette with electrode wire t e, inspection and cleaning of the edges to be welded t cr, cleaning the seams from slag and spatter t br, branding the seams t cl, installing and turning the product, fixing it t ed:

t in \u003d t e + t cr + t br + t ed + t cl, (1.19)

where t in - auxiliary time, min;

t e - time to fill the cassette with electrode wire, min;
t kr - time for inspection and cleaning of welded edges, min;

t br - time to clean the seams from slag and splashes, min;

t cl - time for branding seams, min;

t ed - time for installation and rotation of the product, its fastening, min;

In automatic welding, auxiliary time includes the time for filling the cassette from the electrode wire. This time can be taken equal to t e = 5 min.

The cleaning time of the edges or seam is calculated by the formula:

t cr \u003d L w (0.6 + 1.2 (n c -1)), (1.20)

where t kr - time for inspection and cleaning of welded edges, min;

n with - the number of layers during welding in several passes;

L w - seam length in meters.

The time to install the brand, t cl is taken 0.03 minutes per 1 sign.

The time to install, turn and remove the product, t ed depends on its mass (table 1.7).

Table 1.7 - The norm of time for installation, rotation and removal of the product, depending on its mass

The time for maintenance of the workplace includes the time for setting the welding mode, setting up the machine, cleaning tools, etc. take equal:

t obs \u003d (0.06 ... 0.08) t about, (1.21)

where t obs - time for maintenance of the workplace, hour;

Main time, hour.

The time of breaks for rest and personal needs depends on the position in which the welder performs work. When welding in a convenient position, t p \u003d 0.07 t o.

1.10 Calculation of the amount of deposited metal, consumption of welding consumables, electricity

The mass of deposited metal, (convert to kg), is determined by the formula:

where is the mass of deposited metal, g;

The sum of the areas of the deposited metal of all seams, cm 2;

Metal density, g/cm 3 ;

The sum of the lengths of all seams, see

In the explanatory note, it is necessary to determine by calculation the consumption of electrodes, welding wire, flux, shielding gas for the manufacture of one product and the annual program. When determining the consumption of electrodes, the weight of the deposited metal is taken into account, as well as all the inevitable losses of metal in the welding process due to waste and spatter, in the form of an electrode coating.

The consumption of electrodes in manual arc welding, G el, kg, is determined by the formula:

G el \u003d ψ M ΣHM, (1.23)

where G el - consumption of electrodes in manual arc welding, kg

ψ - consumption coefficient, taking into account the loss of electrodes for cinders, waste and metal spatter;

М ΣНМ is the mass of deposited metal.

The values of ψ for various types and brands of electrodes are indicated in the literature or table 1.8 of this manual.

Wire consumption in automatic submerged arc welding or in CO 2, G p p , kg, is determined by the formula:

where G p p - wire consumption in automatic submerged arc welding or in CO 2, kg;

Weight of deposited metal, kg;

Wire loss factor.

Table 1.8 - Flow coefficient ψ at various ways welding

Welding methods
Manual arc welding with electrodes of brands:
VCC-3, OZL-4, KU-2 AN-1, 0MA-11, ANO-1 UONI-13/45, VSP-1, MR-1, AMO-5, OZS-3, ANO-3, OZS-6, UP-1/5
MR-3, NIAT-6, ZIO-7, ANO-4, OZS-4, K-5A, UONI-13/55 OMM-5, SM-5, VCC-2, TsL-11 UT-15, TsT-17 OZA-1, OZA-2
Automatic submerged arc and electroslag welding
Semi-automatic submerged arc welding
Welding with a non-consumable electrode in inert gases with an additive: - manual Automatic
Automatic and semi-automatic consumable electrode welding in inert gases and in a mixture of inert and active gases
Automatic and semi-automatic welding in carbon dioxide and automatic welding in gas mixtures 50% (Ar + CO 2)

To determine the flux consumption, its consumption for the formation of a slag crust and the inevitable losses for spillage during assembly of the product and for spraying are taken into account.

Flux consumption for the product Gf, kg is determined by the formula:

G f =ψ f G pr, (1.25)

where G f is the mass of the spent flux, kg;

ψ f - coefficient expressing the ratio of the mass of the flux consumed to the mass of the welding wire and depending on the type of welded joint and welding method (table 1.9);

Table 1.9 - Consumption coefficient ψ f for submerged arc welding

The mass of the spent flux m p p , kg, can also be determined from the weight of the deposited metal.

In automatic welding, flux consumption per product Gf, kg, is determined by the formula:

G f \u003d (0.1 ... 1.2) M ΣНМ, (1.26)

In semi-automatic welding, flux consumption per product Gf, kg, is determined by the formula:

G f \u003d (1.2 ... 1.4) M ΣHM, (1.27)

where G f - flux consumption per product, kg;

Weight of deposited metal, kg.

The consumption of carbon dioxide is determined by the formula:

G CO2 \u003d 1.5 G pr, (1.28)

where G CO2 is the consumption of carbon dioxide, kg;

G pr - mass of spent wire, kg.

If the mass of deposited metal M HM of one meter of weld is known, then the power consumption W, kWh, can be calculated from the specific power consumption using the formula:

W = a e M NM, (1.29)

where W - electricity consumption, kWh;

M HM - mass of deposited metal of one meter of the weld, kg;

a e - specific energy consumption per 1 kg of deposited metal, kWh / kg.

For enlarged calculations, the value of a e can be taken equal to:

when welding on alternating current, kWh/kg 3…4

For multi-station DC welding, kWh/kt 6…8

With automatic welding at direct current, kWh/kg 5…8

Submerged, kWh/k 3…4

All calculated data are summarized in table 1.10.

Table 1.10 - Summary table of material consumption

1.11 Calculation of the amount of equipment and its loading

The required amount of equipment is calculated according to the technical process.

We determine the actual fund of the operating time of the equipment Ф d, h, according to the formula:

F D \u003d (D p t n -D pr t c) K pr K s, (1.30)

where Ф d - the actual fund of the operating time of the equipment, h;

D p \u003d 253 - the number of working days;

D pr \u003d 9 - the number of pre-holiday days;

t p - shift duration, hour;

t c \u003d 1 - the number of hours by which the working day before the holidays is reduced (t c \u003d 1 hour);

K by =0.95 - coefficient taking into account downtime of equipment in repair;

K s is the number of shifts.

We determine the total labor intensity, programs T o, n-h, welded structures according to the operations of the technical process:

where T o - total labor intensity, programs, n-h;

IN - annual program, PCS.

The results of the calculations are summarized in Table 1.11.

Table 1.11 - Statement of labor input for the manufacture of welded structures

We calculate the amount of equipment C p for the operations of the technical process:

where С р - quantity of equipment for technical process operations, pcs;

T is the complexity of the program for operations, n-h;

Ф d - the actual fund of the operating time of the equipment, h;

K n - coefficient of compliance with the norms (K n \u003d 1.1 ... 1.2).

T \u003d ΣT pcs V, (1.33)

where T pcs. - the norm of piece time of the welded structure for the operations of the technical process, min;

B - annual program, pcs.

The accepted quantity of equipment, C p, is determined by rounding the estimated quantity upwards to the nearest whole number. It should be borne in mind that the permissible overload of workplaces should not exceed 5-6%.

Calculation of the equipment load factor.

For each operation:

where is the equipment load factor;

С р - quantity of equipment for technical process operations, pcs;

С n is the accepted amount of equipment, pcs.

Calculated average:

where is the average equipment load factor;

The total number of equipment for technical process operations, pcs;

Total accepted quantity of equipment, pcs.

It is necessary to strive to ensure that the average load factor of the equipment is as close as possible to unity. In serial production, its value should be at least 0.75 ... 0.85, and in mass-flow and large-scale production - 0.85 ... 0.76, in single-piece production - 0.8 ... 0.9 in two-shift workshops.

1.12 Calculation of the number of employees

We determine the number of production workers (assemblers, welders). The number of main workers P op is determined for each operation by the formula:

, (1.36)

where P op - the number of main workers, h;

T year - the annual labor intensity of the program for operations, n-h;

F DR - the actual annual fund of working time of one worker, h;

K in - coefficient of performance of production standards (1.1 ... 1.3).

T year \u003d T piece V, (1.37)

where T year - the annual labor intensity of the program for operations, n-h;

T pcs. - the norm of piece time of the welded structure for the operations of the technical process, min;

B - annual program, pcs.

F DR \u003d F D / K s, (1.38)

where F DR - the actual annual fund of working time of one worker, h;

F D - the actual fund of the operating time of the equipment;

K s is the number of shifts.

The number of workers is rounded up to a whole number, taking into account the amount of equipment.

With the flow organization of production, the number of main workers is determined by the number of pieces of equipment, taking into account its load, the possible combination of professions and planned absenteeism for good reasons. Based on this, we determine the total number of main workers P o.r.

We determine the number of auxiliary workers P BP, according to the formula:

, (1.39)

where Р вр - the number of auxiliary workers, people;

We determine the number of employees P sl, according to the formula:

where P sl - the number of employees, people;

Р вр - the number of auxiliary workers, people;

R o.r. - total number of key workers, pers.

Including the number of managers (masters) R hands, according to the formula:

where P hands - the number of managers (masters), people;

We determine the number of specialists (technologists) Р special, according to the formula:

where Pspec - the number of specialists (technologists), people;

P sl - the number of employees, people.

We determine the number of technical performers (timers) Р tech.isp. , according to the formula:

, (1.43)

where R tech. - the number of technical performers (timers), people;

P sl - the number of employees, people.

Enter the calculation results in table 1.12.

Table 1.12 - Number of employees

1.13 Equipment maintenance and operation costs

The cost of power electricity W forces, kWh, is determined by the formula:

, (1.44)

where W forces - the cost of power electricity, kWh;

ΣN - total power of electric motors, kW;

F D - the actual annual fund of the operating time of the equipment, h;

К о.ср - average equipment load factor;

k o - coefficient of simultaneous operation of electric motors (0.6 ... 0.8);

Efficiency C - network efficiency (0.95 ... 0.97);

Efficiency U - efficiency of electric motors (0.8 ... 0.9).

The consumption of compressed air per unit of product is determined by the operations of the technical process, during which compressed air is used, P compress, m 3:

R szh\u003d R h C about P c T piece about. /60, (1.45)

where R szh - compressed air consumption per unit of product, in the performance of which compressed air is used, m 3;

R h - hourly consumption of compressed air, m 3;

C about - the number of pieces of equipment or devices that consume compressed air, pcs;

P c - the number of pneumatic cylinders installed on equipment or fixtures, pcs.,

T pcs. – operation time during which pneumatic cylinders work, min.

For pneumatic tools R h \u003d 2.5 ... 4.5 m 3.

For pneumatic lifts R h \u003d 0.1 ... 0.4 m 3.

For pneumatic cylinders P h \u003d 0.3 ... 0.8 m 3.

1.14 Methods for combating welding deformations

Indicate specific measures to prevent deformations and stress during welding of the designed welded unit or structure, paying attention to the methods of fixing the product to be welded, the assembly unit in the fixture, uniform or uneven heating.

Choose the correct sequence of assembly and welding operations, choose a rational form of edge preparation, welding method, welding modes, if necessary, then the type of heat treatment.

1.15 Choice of quality control methods

Indicate which quality control methods are used depending on the nature and purpose of the structure, the degree of its responsibility, the design of welds and the grade of the material being welded (external inspection of welds, hydraulic testing, kerosene testing, mechanical testing, radiation, ultrasonic, magnetic, etc.) .

2 Design section

2.1 Description of the beam structure

Describe in detail the parts that make up the welded structure. Describe the purpose of the welded structure, the conditions of its operation. To do this, study the literature,,.

2.2 Selection and justification of the metal of the welded column

The choice and justification should be made taking into account the following requirements:

Ensuring strength and rigidity at nominal manufacturing costs, taking into account the maximum savings in metal and reducing the mass of the welded structure;

Guaranteed condition for good weldability with minimal softening and reduced plasticity in the zones of welded joints;

Ensuring the reliability of operation of the structure under given loads, aggressive environments and variable temperatures.

Having justified the choice of steel grade, it is necessary to indicate the chemical composition and mechanical properties of steel in the form of table 1 and table 2, respectively.

Table 1 - Chemical composition of steel

2.3 Calculation and design of the column bar

Approximately we take the coefficient of longitudinal bending

We determine the required cross-sectional area of \u200b\u200bthe column rod A tr, cm 2

(1)

where N - load calculation, kN

R y - design resistance of the metal, kN / cm 2

Since the section of the column consists of two channels, we find the required area of \u200b\u200bone channel A¢ tr, cm 2

According to the assortment tables, we select the actual cross-sectional area of \u200b\u200bone channel (A¢ d) close to the required area (A¢ tr) and enter the geometric characteristics of the channel:

- channel number;

A¢ d cm 2;

I x, cm 4;

I y, cm 4;

We determine the actual value of the cross-sectional area of \u200b\u200bthe rod A d, cm 2

A d \u003d 2A¢ d (3)

Determine the flexibility of the column rod relative to the x-x axis, l x

where I p is the calculated length of the column rod, depending on the fixing of its ends, cm;

r x - radius of gyration, cm.

By l x determine the actual value of the coefficient of buckling j d .

We check the column rod for stability s, kN / cm 2

(5)

where у с is the coefficient of working conditions.

The column bar must have a minimum section that satisfies the stability requirement. Undervoltage and overvoltage should not exceed 5%.

2.4 Calculation of the design of connecting strips

We determine the distances I in between the connecting strips 2 in accordance with Figure 2, see.

I in \u003d l in * r y (6)

where l in - the flexibility of one branch, l in \u003d 30 ... 40;

r y is the radius of inertia of one channel 1 relative to its own axis, see Fig.

We determine the distance between the channels (b), based on the condition of equal stability.

To do this, from the equilibrium condition

(7)

We express the flexibility of the rod with respect to y-axis, l

We determine the required radius of inertia of the rod section r¢ y relative to the y-y axis, see Fig.

We determine the distance between the branches of the column b, see If the channel shelves are located inward in accordance with Figure 3

If the channel flanges are located outward in accordance with Figure 3

Estimated dimensions (b) are rounded up to an even integer.

We determine the geometric characteristics of the section of the rod.

Moment of inertia of the column section relative to the y-y axis I y, cm 4

(12)

If the channel shelves are located inside, then a, cm 4

If the channel shelves are located outward, then a, cm

We determine the actual value of the radius of inertia of the rod section relative to the y-y axis, r² y, cm.

Determine the actual flexibility of the column bar with respect to osu uu, l

We determine the reduced flexibility of the rod, l pr

(17)

If l pr £l x, then the section of the rod is chosen correctly and the rod is not checked for stability.

If l pr ³l x, then l pr determine the actual coefficient of buckling j d and check the column rod for stability.

We determine the conditional transverse force F arb, kN, arising in the section of the rod as a result of the bending moment.

For steels with s in up to 330 MPa

F conv \u003d 0.2 * A d (18)

For steels with s in up to 440 MPa

F conv \u003d 0.3 * A d (19)

We determine the force T, cutting the bar, provided that the bars are located on both sides, kN

We determine the moment M, bending the bar in its plane, kN cm, provided that the bar is located on both sides

We accept plank sizes.

Plank height d pl, cm.

d pl \u003d (0.5 ... 0.7) d

Strip thickness S pl, cm.

Moreover, the thickness of the bar is taken S pl \u003d 10 ... 12 mm.

2.5 Calculation of welds attaching planks to column branches

We determine the stress from the bending moment in the seam kN / cm 2

where W w is the moment of resistance of the weld, cm 3

(23)

К f – weld leg, cm (К f =(0.6…0.8)S pl), cm;

I w - the length of the weld that attaches the bar to the column rod, cm (I w \u003d d pl + 2I w), cm.

We determine the shear stress in the weld, kN / cm 2

where A w is the cross-sectional area of the weld, cm 2

We determine the resultant stress t pr, kN / cm 2

(25)

where R wf is the design resistance of the welded joint, kN / cm 2

2.6 Calculation and design of the column base

The base serves to distribute the load from the rod evenly over the area of support and secures the lower end of the column.

The base consists of a base plate 3 and 2x traverses 4. To reduce the thickness of the plate, if by calculation it turned out to be more than the nominal one, it is reinforced with stiffeners. Anchor bolts fix the correct position of the column relative to the foundation.

We determine the required (calculated) area of \u200b\u200bthe base plate A p, cm 2

where N is the design reinforcement in the string, kN;

R cm 6 - design resistance of concrete (foundation) to collapse,

R cm 6 \u003d 0.6 ... 0.75 kN / cm 2

Determine the width of the base plate B, cm

B=h+2S TP 2C (27)

where h is the height of the profile section, cm;

S TP - thickness of the traverse, cm (S TP \u003d 1.2S pl);

C - cantilever part of the base plate, cm

С=10…15 cm.

The final size V d is accepted according to GOST 82-70.

Determine the length of the base plate L, cm

The final length of the base plate L d is taken according to GOST 82-70, depending on the design of the section.

We determine the actual area of \u200b\u200bthe base plate A d, cm 2

A d \u003d B d ×L d (29)

Determine the thickness of the base plate S op.pl. from the condition of its work on bending.

We determine the bending moment M 1 on the cantilever section 1 along the length of 10 mm, in accordance with Figure 5, kN × cm

where s b is the bearing pressure of the foundation, kN / cm 2

where A d is the actual area of \u200b\u200bthe base plate, cm 2.

We determine the bending moment M 2 in section 2, based on four sides, kN × cm

M 2 \u003d α × s b × h 2 (32)

where α is a coefficient depending on the ratio of the longer side to the shorter side in section 2 - table 3.

Table 3 - Coefficient for calculating plates supported on four sides

We determine the bending moment M 3 in section 3, kN × cm

M 3 \u003d b × s b × h 2 (33)

where b is a coefficient depending on the ratio of the fixed side a to the loose side h - table 4.

Table 4 - Coefficient for calculating slabs supported on three sides

Plate thickness S op.pl. determined by the maximum of the three bending moments, mm

(34)

Accept the diameters of the anchor bolts constructively:

For hinged bases d=20…30 mm.

For rigid bases d=24…36 mm.

For rigid bases, we use anchor plates 5, which are welded to the traverses during the installation of the column in accordance with Figure 6.

The thickness of the anchor tiles S a = 30 ... 40 mm.

Tile width b a is used depending on the diameter of the anchor bolts, mm

b a =2.2d+(10…20) (35)

We determine the total length of the welds SI w, attaching the traverse to the branches of the column, cm

(36)

where b is a coefficient depending on the welding method;

K f - the leg of the weld is taken according to the smallest thickness of the metal according to SNiP 11-23-81 (p. 48. table 38), see

Determine the height of the traverse h tr, cm

2.7. Calculation and design of the column head and its joints

The head serves as a support for beams, trusses and distributes the concentrated load on the column evenly over the entire section of the rod.

The pressure on the column is transferred to the base plate, and then to the support rib and through the rib to the branch of the column, and then it is evenly distributed over the section of the column. The transverse rib prevents twisting of the support ribs.

We accept the thickness of the base plate of the head S o.pl \u003d 16 ... 25 mm.

We accept the thickness of the supporting ribs S p = 14 ... 20 mm.

If the base plate of the head is installed on the milled ends of the support ribs, then the legs of the welds attaching the base plate to the support ribs are adopted constructively:

K f \u003d 6 mm with S o.pl \u003d 16 ... 20 mm;

K f \u003d 8 mm with S o.pl \u003d 16 ... 25 mm;

From the support ribs, the pressure on the column wall is transmitted through vertical fillet welds.

Determine the required length of vertical fillet welds I w, cm

(38)

where b is a coefficient depending on the welding method;

K f - the leg of the seam is taken according to the minimum thickness of the metal, see.

We check the edge for a cut t, kN / cm 2

where A r is the area of the rib, cm 2;

R s - design shear resistance, kN / cm 2

A p \u003d 2 × S p × I w (40)

2. 8 Choice of welding method and quality control methods for welded joints

For the manufacture of the column, we select and justify the method of welding, based on ensuring high productivity and workmanship. We select and justify quality control of welded joints.

2. 9 Selection of welding modes and welding equipment

Based on the selected welding method, it is necessary to select and justify the mode parameters.

criterion optimal choice modes is the maximum productivity of the welding process, provided that the required geometric dimensions of the weld cross section are obtained, regulated by GOST 14771-76, GOST 5264-80, GOST 8713-79 and sufficiently low metal losses for waste and spatter.

The main parameters of the automatic, semi-automatic submerged arc welding mode are welding current, diameter, welding wire feed speed, arc voltage, welding speed.

Table 5 - Welding modes

The calculation of welding modes is always made for a specific case.

We determine the welding speed, V sv, m / h

where α n is the deposition coefficient;

I - current strength, A;

g - specific density (g=7.85 g/cm 3);

A w - cross-sectional area of \u200b\u200bthe seam, mm 2

(42)

where K f is the leg of the seam, mm;

q is the height of the reinforcement of the seam, mm.

q=0.3 K f (43)

determine the welding wire feed speed, V under, m/h

(44)

where d is the diameter of the welding wire, mm.

Considering the chosen method and modes of welding, we select welding equipment. We specify the calculated speed ranges according to the passport data of the semiautomatic device. The following describes the principle of operation, design and technical specification selected welding equipment.

To control the welds of the column, it is advisable to perform a macroanalysis, check the welds for the presence of internal defects. Macroanalysis is performed by controlling and measuring the dimensions of welds using special templates.

The presence of internal defects can be detected using ultrasonic or magnetographic quality control methods.

SECTION 3 OCCUPATIONAL SAFETY

This section should address the following questions:

Industrial hazards in welding;

Measures to combat air pollution;

Measures of protection against electric shock;

Measures to protect against arc radiation and burns;

Safety measures during the operation of cylinders with protective gas;

Fire prevention measures during welding;

Measures to combat environmental pollution;

Calculation of ventilation at workplaces of the assembly and welding area;

Calculation of lighting assembly and welding area.

3.1 Calculation of ventilation at the workplaces of the assembly and welding area.

Local suctions can be combined with process equipment and not connected with the equipment. They can be stationary and non-stationary, mobile and motionless.

For manual, automatic and semi-automatic welding in shielding gases of small parts at stationary workplaces, it is recommended to adopt the following device:

Uniform suction panels;

Tables with movable cover and built-in local suction;

Tables for the welder with built-in (upper and lower) suction, etc.

Tables at stationary posts and cab are equipped with uniform suction panels of the following sizes:

Gp 600x645, Gp 750x645, Gp 900x645 mm.

The hourly exhaust volume of polluted air L in, m 3 / h is determined by the formula

, (2.1)

V is the speed of air movement in the duct. (V \u003d 3 ... 4 m 3 / h);

A - cross-sectional area of the duct, m 2.

A \u003d 0.25 x A p, (2.2)

where A is the cross-sectional area of the duct, m 2;

And n - panel area, m 2.

Having calculated the value of L in, we select a fan and the type of electric motor for local suction.

Types of local suctions for submerged arc welding: slot, perforated, approximate, flux suction, etc.

The amount of air L, m 3 / h removed by local suction is determined by the formula

where L is the amount of air removed by local suction, m 3 /h;

I is the strength of the welding current, A;

K - coefficient:

For slot suction K=12;

For double suction K=16.

Having calculated the value of L, we select the fan number and the type of electric motor for local suction.

No. 5 - with the number of suctions up to 8;

No. 8 - with the number of suctions from 8 to 40.

Calculation example.

Select a fan and an electric motor for local exhaust ventilation of the welding station when welding small items.

For mechanized welding in CO 2, a local suction panel of uniform suction is taken 600x645 mm (A n).

We determine the hourly volume of polluted air exhaust L in, m 3 / h according to the formula

, (2.4)

where L in is the hourly volume of polluted air exhaust, m 3 / h;

V is the speed of air movement in the duct, m 3 / h, (V = 3 ... 4 m 3 / h);

A - cross-sectional area of the duct, m 2, (A \u003d 0.25A p).

A \u003d 0.25A n \u003d 0.25 x 0.6 x 0.645 \u003d 0.0967 m 2,

L in \u003d 3 x 0.0967 x 3600 \u003d 1044 m 3 / h.

We select according to the table fan No. 2 with air exchange 1200 m 3 / hour, electric motor 4A100S2U3

Table 2.1 - Data for selection of EVR series centrifugal fans

3.2 Lighting of the assembly and welding area

In assembly and welding shops, it is advisable to create a general localized or uniform general lighting system using portable local lighting fixtures. Illumination levels for welding work are set in accordance with regulatory documents for fluorescent lamps E cf = 150 lx, for incandescent lamps E cf = 50 lx.

The number of lamps L required for lighting is calculated by the formula

, (2.5)

where L is the number of lamps, pcs;

E cf - average illumination, lx;

A - the area of \u200b\u200bthe room, m 2;

F o - the luminous flux of one lamp, lm, is taken according to table 2.3;

η is the luminous flux utilization factor.

The coefficient η is chosen according to Table 2.2 depending on the indicator of the room i

, (2.6)

where i is the indicator of the room;

a and b - the width and length of the room, m;

H r - the height of the fixtures above the working surface, m, (H r ≈ 5...6 m).

Table 2.2 - Values of the luminous flux utilization factor depending on the indicator of the room.

Table 2.3 - Light and electrical parameters of lamps (voltage 220V)

Incandescent lamps		Fluorescent lamps
	Light flow F, lm		Light flow F, lm

Note - When using the table, select the lamp type first.

4 ECONOMIC SECTION

4.1 Calculation of material costs

Material costs include the costs of raw materials, materials, energy resources for technological purposes.

Material costs (MZ, rub.) are calculated according to the formula

where MZ - material costs, rub.;

So.m - the cost of basic materials, rub.;

St.m - the cost of auxiliary materials, rub.;

Sen is the cost of energy resources, rub.

The main ones include the materials from which structures are made, and during welding processes, also welding materials: electrodes, wire, filler material. The cost of basic materials, taking into account transportation and procurement costs (So.m, rub.), is calculated by the formula

where So.m - the cost of basic materials, taking into account transport and procurement costs, rub.;

Tsm, Tss.pr - the price of metal and welding wire, respectively, rub.;

m W - mass of the workpiece, kg;

Ns.pr - consumption rate of welding wire per 1 part, kg .;

Ktr is a coefficient that takes into account transportation and procurement costs, it can be taken in the range of 1.05 ... 1.08.

Auxiliary welding materials include flux, oxygen, shielding and combustible gases. The cost of auxiliary materials, taking into account transportation and procurement costs (Sm, rub.), Is calculated by the formula

, (3.3)

where St.m - the cost of auxiliary materials, taking into account transport and procurement costs, rubles;

Tsv.m - the price of auxiliary materials per unit, rub.;

Nv.m - consumption rate of auxiliary materials (carbon dioxide), kg.

m - the number of technological operations.

The article “Fuel and energy for technological purposes” (Sen, rub.) includes the costs of all types of fuel and energy that are consumed in the production process of this product (power energy, compressed air) and is calculated by the formula

, (3.4)

where Sen - the cost of all types of fuel and energy that are consumed in the process of production of this product, rub.;

Sal is the cost of electricity for driving force, rub.;

Sszh.v - the cost of compressed air, rub.

Electricity costs for motive power (Sel, rub.) are calculated by the formula

where Sal is the cost of electricity for driving force, rub.;

Tsen - tariff for 1 kWh of electricity, rub.;

Nel - the rate of electricity consumption for the manufacture of the main part, kW

Compressed air costs (Cszh.v, rub.) are calculated by the formula

, (3.6)

where Ссж.в - costs for compressed air, rub.;

Cszh.v - the price of 1m 3 compressed air, rub.;

Rszh.v - the need for compressed air to complete the annual program, m 3.

B – annual program, pcs.;

3 - the number of manufactured parts (1 - main, 2 - loaded), pcs.

Substituting the values of formulas (3.2), (3.3) and (3.4) into formula (3.1) we find the cost of material costs.

4.2 Calculation of wages of production workers, deductions and tax from her

This subsection provides for the calculation of the basic and additional wages of production workers, deductions and tax from it, which are included in the cost.

The wages of production workers (SW, rubles) consist of 2 parts:

- basic salary

- additional salary.

It is calculated according to the formula

, (3.7)

where

ZPO - the basic wages of production workers, rubles;

ZPd - additional wages of production workers, rub.

The article “Basic wages of production workers” includes payment for basic workers at piece rates based on the labor intensity of work, additional payments for harmful conditions labor and bonuses for production results of work.

The basic salary of production workers is calculated by the formula

, (3.8)

where

ΣRsd - total piece-rate for the manufacture of a part, rub.;

Kpr - bonus factor;

Dvr - additional payment for work in hazardous working conditions, rub.

The piece rate (Rsd, rub.) for the manufacture of a part for all operations is calculated by the formula

, (3.9)

where Rsd - piece-rate for the manufacture of parts for all operations, rub.;

Тst i - hourly wage rate of the main worker of the corresponding category, rub.;

Tsht - the norm of piece time for the operations of the technical process, min.;

The results of the calculations are entered in table 3.1.

Table 3.1 - Summary sheet of prices for technical process operations

Welding workers for work in hazardous working conditions, an additional payment for harmfulness (Dvr, rubles) is made, which is calculated according to the formula

, (3.10)

where Dvr - surcharge for harmfulness to welders, rub.;

Tst 1 - monthly tariff rate of the 1st category, rub.;

Tvr - operating time in hazardous conditions, min.

The article “Additional wages of production workers” (ZPd, rubles) reflects the payments provided for by the legislation for time not worked at work (payment of vacation pay, compensations, performance of state duties, payment of privileged hours to adolescents, nursing mothers). The amount of payments is usually provided within the limits of up to 15% of the basic salary and is calculated according to the formula

where ZPd - payments provided for by law for time not worked at work, rubles;

ZPO - the basic wages of production workers, rubles;

Kd is the coefficient of additional wages.

Substituting the values of formulas (3.8) and (3.11) into formula (3.7), we find the wages of production workers.

Deductions for the state social insurance(Os.s, rub.) to the Fund social protection population are calculated using the formula

, (3.12)

ZP - wages of production workers, rub.;

hс.с is the standard of social insurance contributions in force at the time of the implementation of the DP, %.

Contributions to the State Fund for the Promotion of Employment (Of.z, rubles) are calculated according to the formula

, (3.14)

where Of.z - deductions to the state fund for the promotion of employment, rubles;

ZP - wages of production workers, rub.;

hof.z - the standard for contributions to the state fund for the promotion of employment, in force at the time of the implementation of the DP,%.

The emergency tax (Nch, rub.) for the liquidation of the consequences of the Chernobyl accident is calculated by the formula

where Hch - emergency tax, rub.;

ZP - wages of production workers, rub.;

hch – extraordinary tax rate effective at the time of implementation of the DP, %.

4.3 Calculation of the total cost of the product

Before calculating the total cost of manufacturing a product, the production cost is calculated.

Production cost (Cf, rub.) includes the cost of manufacturing products and is calculated by the formula

where Spr - production cost, rub.;

MZ is formula (3.1);

ZPO - formula (3.8);

ZPd - formula (3.11);

Os.s - formula (3.12);

Of.z - formula (3.14);

LF - formula (3.15);

Рpr - general production costs, rub.;

Рhoz - general business expenses, rub.

The article “General production expenses” (Рpr, rub.) includes expenses for wages of managerial and maintenance personnel of workshops, auxiliary workers; depreciation; expenses for the repair of fixed assets; labor protection of workers; for the maintenance and operation of equipment, signaling, heating, lighting, water supply for workshops, etc. These costs are calculated as a percentage of the basic wages of production workers according to the formula

, (3.17)

where Ppr - the cost of wages for management and maintenance personnel of shops, auxiliary workers; depreciation; expenses for the repair of fixed assets; labor protection of workers; for the maintenance and operation of equipment, signaling, heating, lighting, water supply of workshops, etc., rub.;

ZPO - the basic wages of production workers, rubles;

%Rpr - percentage of overhead costs,%;

%Ppr = 280-500%.

The article “General business expenses” (Rhoz, rubles) includes: labor costs associated with the management of the enterprise as a whole, travel expenses; stationery, postal-telegraph and telephone expenses; depreciation; expenses for the repair and operation of fixed assets, heating, lighting, water supply for the plant management, for security, signaling, maintenance of cars, compulsory insurance of employees in Belgosstrakh against industrial accidents and occupational diseases. These costs are calculated as a percentage of the basic wages of production workers using the formula

, (3.18)

where Rhos - labor costs associated with the management of the enterprise as a whole, travel expenses; stationery, postal-telegraph and telephone expenses; depreciation; expenses for the repair and operation of fixed assets, heating, lighting, water supply for the plant management, for security, signaling, maintenance of cars, compulsory insurance of employees in Belgosstrakh against industrial accidents and occupational diseases, rubles;

ZPO - the basic wages of production workers, rubles;

%Phos - the percentage of general business expenses,%;

%Phos = 230-350%.

Substituting the values of formulas (3.1), (3.8), (3.11), (3.12), (3.14), (3.15), (3.17), (3.18) into formula (3.16), we find the production cost.

The total cost (Cpol, rubles) includes the costs of production and sales of products and is calculated by the formula

where Spol - full cost, rub.;

Sp - formula (3.16);

Рвн - non-production expenses, rub.;

Oin.f - deductions to the innovation fund, rub.

The article “Non-production expenses” (Rvn, rubles) includes expenses for the production or purchase of containers, packaging, loading products and delivering them to the station, advertising, participation in exhibitions. These costs are calculated using the formula

, (3.20)

where Rvn - expenses for the production or purchase of containers, packaging, loading products and delivering them to the station, advertising, participation in exhibitions, rubles;

%Rvn - percentage of non-production costs;

%Pvn = 0.1-0.5%;

Spr - production cost, rub.

Contributions to the innovation fund (Oin.f, rub.) are calculated according to the formula

, (3.21)

where Oin.f - deductions to the innovation fund, rub.;

hin.f - the rate of deductions to the innovation fund, valid at the time of the implementation of the DP,%;

Spr - production cost, rub.;

Rvn - expenses for the production or purchase of containers, packaging, loading products and delivering them to the station, advertising, participation in exhibitions, rub.

Substituting the values of formulas (3.16), (3.20), (3.21) into formula (3.19) we find the value of the total cost of manufacturing the part.

The results of the calculations are entered in table 3.2.

Table 3.2 - Costing for compared options

Name of costing items	Amount, rub.	Deviations
Name of costing items
1 Cost of basic materials (minus returnable waste) including transportation and procurement costs
2 The cost of auxiliary materials, taking into account transportation and procurement costs 3 Cost of energy resources for technological purposes
Total material costs
4 Basic wages of production workers
5 Additional wages for production workers
6 Contributions to the Social Protection Fund 7 Emergency tax and mandatory contributions to the state fund for the promotion of employment
8 General production costs
9 General expenses
Total production cost
10 Non-manufacturing expenses
11 Contributions to the innovation fund
Total full cost

Deviations are calculated as follows:

a) in absolute terms, rub.

b) in relative terms

4.4 Comparison of process options for manufacturing a part

The annual economic effect of reducing the cost by reducing consumption (raw materials, materials, fuel, energy, reducing labor intensity for operations, reducing rejects and downtime of equipment) is calculated by the formula

where E is the annual economic effect of cost reduction due to consumption reduction;

Spol PR, Spol BAZ - the total cost of the part for the designed and basic options, rub.;

B - annual program, pcs.

- the complexity of manufacturing the part;

- coefficient of use of basic materials;

- material consumption;

- piece rate;

- the total cost of manufacturing the part;

– annual economic effect.

Material consumption (Me, rub/rub) is calculated by the formula

where Me - material consumption, rub / rub.;

MZ - material costs, rub.;

Spol - full cost, rub.

The main technical and economic indicators are entered in table 3.3.

Table 3.3 - Technical and economic indicators

End of table 3.3.

On this, the goal of the economic part of the graduation project is achieved.

The student formulates the conclusion based on the results of the analysis of the data in tables 3.2 and 3.3, indicating the reasons for the deviations of the calculation items for the manufacture of the part, the annual economic effect and economic feasibility this graduation project.

CONCLUSION

In conclusion, it is necessary to reflect the design and technological measures developed in the graduation project, especially those that have advantages over the base case.

Particular attention should be paid to the issues of resource-saving technologies:

Replacement of the base metal in order to reduce metal consumption, labor intensity, consumption of welding materials and electricity, increase the strength of structures;

The use of special devices and mechanisms that provide an increase in productivity and quality in the manufacture of welded structures;

Choosing a more economical welding method;

Application of forced welding modes;

Rational placement of equipment with optimal use of production space.

LIST OF USED SOURCES

1 Blinov A.N. Welded structures. - M.: Stroyizdat, 1990. -350 p.

2 Verkhovenko L.V., Tunin A.N. Handbook of a welder.: Higher school, 1990. - 497 p.

3 Dumov S.I. Technology of electric fusion welding. -M.: Mashinostroenie, 1978. - 315 p.

4 Kozvyakov A.F., Morozova L.L. Labor protection in mechanical engineering. - M.: Mashinostroenie, 1990. - 255 p.

5 Kurkin S.A., Nikolaev G.A. Welded structures. - M.: . High school. 1991. -397 p.

6 Mikhailov A.I. Welded structures. - M.: Stroyizdzt. 1993. - 366 p.

7 Nikolaev G.A. Welded structures. - M.: Higher school. 1983.-343s.

8 Stepanov B.V. Welder's Handbook. - M.: Higher school, 1990.-479s.

9 E Belokon VM - Production of welded structures. - Mogilev. 1998.-139p.

10 Kulikov V.P. Fusion welding technology. - Mn. PRO design; 2000. - 256 p.

11 Potapyevskiy A.G. Welding in shielding gases with a consumable electrode. - M.: Mashinostroenie, 1974. - 233 p.

12 Yuriev 8.P. Reference manual on the rationing of materials and electricity for welding equipment. - M.: Mashinostroenie. 1972. -150 p.

13 Kozyanov A.F., Morozova L.L. Labor protection in mechanical engineering. – M.: Mashinostroenie, 1998. - 256 p.

14 Brouds M.E. Occupational safety during welding in mechanical engineering - M .: Mashinostroenie, 1978. - 186 p.

15 Belov S.V., Brinza V.N. and others. Safety of production processes: a Handbook - M .: Mashinostroenie, 1985. - 448 p.

16 Basic provisions on the composition of costs included in the cost of products (works, services). Approved by the Decree of the Ministry of Economy, the Ministry of Finance, the Ministry of Statistics and Analysis, the Ministry of Labor. Bulletin of the Ministry of Taxes and Dues of the Republic of Belarus - 2002 No. 29

17 Karpey T.V. "Economics, organization and planning industrial production»: Proc. allowance. - Mn. Design PRO, 2004. - 328 p.

18 Dumov S.I. Technology of electric fusion welding. Laboratory work - M .: Mashinostroenie, 1982. - 151 p.

19 Dumov S.I. Technology of electric fusion welding. – M.: Mashinostroenie, 1987. – 458 p.

20 Stepanov V.V. Welder's Handbook. - M.: Mashinostroenie, 1983. - 559 p.

21 Verkhovenko L.V., Tukin A.K. Welder's Handbook. – Mn.: Vysh. school, 1990. - 479 p.

22 Blinov A.N., Lyapin K.V. Welded structures. - M., 1990.

23 Gulyaev A.I. Technology and equipment of contact welding. - M., 1985.

24 Kurkin S.A., Nikolaev G.A. Welded structures. - M., 1991.

25 Mikhailov A.M. Welded structures. - M., 1983

26 Prokh L.Ts., Shpakov B.M., Yavorskaya N.M. Handbook of welding equipment. - Kyiv, 1983.

STANDARDS

GOST 10051-75. Coated metal electrodes for manual arc welding of surface layers with special properties.

GOST 10052-75. Coated metal electrodes for manual arc welding of high-alloy steels with special properties. Types.

GOST 10157-79. Argon gaseous and liquid. Specifications.

GOST 10543-82. Wire steel surfacing. Specifications.

GOST 14771-76. Arc welding in shielding gas. Connections are welded. Basic types, structural elements and dimensions.

GOST 16130-90. Welding wire and rods made of copper and copper-based alloys. Specifications.

GOST 2.312-72. ESKD. Conditional images and designations of seams of welded joints.

GOST 20461-75. Helium gaseous. Method for determining the volume fraction of impurities by emission spectral analysis.

GOST 22366-93. Iron-based electrode surfacing tape. Specifications.

GOST 2246-70. Wire steel welding. Specifications.

GOST 23949-80. Electrodes tungsten welding nonconsumable. Specifications.

GOST 26101-84. Wire powder surfacing. Specifications.

GOST 26271-84. Flux-cored wire for arc welding of carbon and low-alloy steels. General specifications.

GOST 5264-80. Manual arc welding. Connections are welded. Basic types, structural elements and dimensions.

GOST 7871-75. Welding wire from aluminum and aluminum alloys. Specifications.

GOST 8050-85. Carbon dioxide gaseous and liquid. Specifications.

GOST 8713-79. Submerged arc welding. Connections are welded. Basic types, structural elements and dimensions.

GOST 9087-81 E. Welding fluxes. Specifications.

GOST 9466-75. Coated metal electrodes for manual arc welding of steels and surfacing. Classification and general specifications.

GOST 9467-75. Coated metal electrodes for manual arc welding of structural and heat-resistant steels. Types.

STB 1016-96. Connections are welded. General specifications.

GOST 2246-70. Welding steel wire: Specifications.

GOST 5264-80. Manual arc welding: Welded joints: Basic types, structural elements and dimensions.

GOST 8713-79. Submerged arc welding: Welded joints: Main types, structural elements and dimensions.

GOST 11533-75. Automatic and semi-automatic submerged arc welding: Joints welded at acute and obtuse angles: Main types, structural elements and dimensions.

GOST 14771-76. Arc welding in shielding gas: Welded joints: Basic types, structural elements and dimensions.

GOST 14776-79. Arc welding: Welded spot joints: Main types, structural elements and dimensions.

GOST 14806-80. Arc welding of aluminum and aluminum alloys in inert gases: Welded joints: Main types, structural elements and dimensions.

GOST 15164-78. Electroslag welding: Welded joints: Main types, structural elements and dimensions.

GOST 15878-78. Contact welding: Welded joints: Basic types, structural elements and dimensions.

GOST 16037-80. Welded steel pipeline joints: Main types, structural elements and dimensions.

GOST 23518-79. Arc welding in shielding gases: Welded joints at acute and obtuse angles: Main types, structural elements and dimensions.

Calculation of wages of production workers, deductions and tax from it

THE CALCULATION IS PERFORMED BY THE STUDENT Surname I.О.

GROUP No. 1-T

This section provides for the calculation of the basic and additional wages of production workers, deductions and tax from it, which are included in the cost.

Labor costs are calculated using the formula

ZP=ZPo+ZPd, (C1)

where

ZPO - basic salary, rub.;

ZPd - additional wages, rub.

The article "basic wages of production workers" includes the wages of the main workers directly involved in the manufacture of products, based on the labor intensity of the work.

The basic salary is determined by the formula

Zpo \u003d (Rsd3 + ... + Rsd6) * Kpr + Dvr, (C2)

where ZPO is the basic salary, rub.;

Rsd - total piece-rate per unit of product, rub.;

Кр – bonus factor, (enterprise data) = 0;

Dvr - additional payment and harmful working conditions, rub.

The total piece-rate for the manufacture of a unit of a product is determined

Rsd \u003d Tst * Tshti / 60, (C3)

where Rsd is the total piece-rate per unit of product, rub.;

Тst.і - hourly tariff rate for the category of work performed, taking into account the multiplying factor, rub.;

Тsht.і - piece time of processing the product according to the operations of the technical process, min.

The name of the operation of the technological process of the 3rd category -

Tst3 of the third category = 0 rub.

The norm of piece time Тsht3 = 0 min.

The name of the operation of the technological process of the 4th category -

Tst4 of the fourth category = 0 rub.

The norm of piece time Тsht4 = 0 min.

The name of the operation of the technological process of the 5th category -

Tst5 of the fifth category = 0 rub.

The norm of piece time Тsht5 = 0 min.

The name of the operation of the technological process of the 6th category -

Tst6 of the sixth category = 0 rub.

The norm of piece time Тsht6 = 0 min.

Surcharge for harmful working conditions are calculated by the formula

Dvr=Tst1*Tvr*(0.10…0.31)/100*60, (C4)

where Dvr - additional payment for harmful working conditions, rub.

Tst1 - tariff monthly rate of the 1st category = 0 rubles.

Tvr - time of work in harmful working conditions = 0 min.

Coefficient within (0.10…0.31) = 0

Dvr = 0 rub.

Table C.1 - Summary bill of prices for process operations

BASIC SALARY WILL BE

ZPO = 0 rub

The article “Additional wages of production workers” reflects the payments provided for by the legislation for time not worked in production (payment of vacation pay, compensations, fulfillment of state obligations, payment of privileged hours to adolescents, nursing mothers). The amount of payments is usually provided within 10% of the basic salary

ZPd = 0.1-ZPo (C5)

ADDITIONAL PAYMENT WILL BE

THE WAGE OF INDUSTRIAL WORKERS WILL BE

Contributions for state social insurance (Os.s, rub) to the Social Protection Fund is 35% of the total salary and are calculated according to the formula

Os.s=hs.s*ZP/100, (C6)

where Ос.с - deductions for state social insurance, rub.;

hс.с - deduction standard;

ZP - labor costs, rubles;

Os.c=0 rub.

The emergency tax for liquidation of consequences at the Chernobyl NPP (Nch, rub.) is 3% and contributions to the state fund for the promotion of employment of the population (Of.z) are 1%, paid in a single payment from the total salary and calculated according to the formulas

Hch \u003d hh * ZP / 100, (C7)

Of.z \u003d hf.z * ZP / 100, (C8)

where Nch - emergency tax for liquidation of consequences at the Chernobyl nuclear power plant, rub.;

Of.z - deductions to the state fund for the promotion of employment, rubles;

ZP - labor costs, rubles;

hh, hf.z - standards for tax and deductions, respectively, %

Of.z \u003d 0 rub.

Appendix D

Prices for materials and energy resources for the manufacture of a part

Table D.1 - Prices for materials and energy resources for the manufacture of parts

Appendix E

Tariff categories and coefficients

Table E.1 - Tariff grades and coefficients

Note: 1) The monthly tariff rate for calculating the additional payment for harmful working conditions is 97,504 rubles. at a rate of USD 2153.

Students should take the technical conditions for the manufacture of welded structures at the factories in the OGS or at the assembly and welding bureau, where they undergo technological practice.

As the main materials used for the manufacture of critical welded structures (supervised by GOSPROMATOMNADZOR) operating under dynamic loads, alloy steels according to GOST 19281-89 or ordinary carbon steels of at least grade St3ps according to GOST 380-94 should be used. For non-critical welded structures, steels of at least grade St3ps according to GOST 380-94 should be used.

Compliance of all welding consumables with the requirements of the standards must be confirmed by the certificate of the supplying plants, and in the absence of a certificate, by the test data of the plant's laboratories.

In manual arc welding, electrodes of at least type E42A in accordance with GOST 9467-75 with a rod made of Sv-08 wire in accordance with GOST 2246-70 should be used.

When welding in carbon dioxide, a wire of at least Sv-08G2S in accordance with GOST 2246-70 should be used.

Welding wire must be free of rust, oil and other contaminants.

The requirements for blanks for welding provide that the parts to be welded from sheet, shaped, sectional and other rolled products must be straightened before assembly for welding.

After rolling or bending, the parts must not have cracks and burrs, tears, waviness and other defects.

The need for machining the edges of parts should be indicated in the drawings and technological processes.

Parts supplied for welding must be accepted by the Quality Control Department.

The assembly of the parts to be welded must ensure the presence of a specified gap within tolerance along the entire length of the joint. The edges and surfaces of parts at the locations of welds to a width of 25-30 mm must be cleaned of rust, oil and other contaminants immediately before assembly for welding.

Parts intended for contact welding at the joints must be cleaned from both sides of scale, oil, rust and other contaminants.

Parts with cracks and tears formed during manufacture are not allowed to be assembled for welding.

These requirements are provided with technological equipment and appropriate tolerances for assembled parts.

When assembling, force adjustment is not allowed, causing additional stresses in the metal.

The assembly for welding must ensure the linear dimensions of the finished assembly unit within the tolerances indicated in Table 2.1.

Table 2.1 - Limit deviations of welded assembly units

The cross section of tacks is allowed up to half the cross section of the weld. Tacks should be placed at the locations of the welds. The applied tacks must be cleaned of slag.

Tacking of welded structures during assembly must be carried out using the same filler materials and requirements as when making welds.

The dimensions of the tacks must be indicated in the process charts.

Only certified welders with a certificate establishing their qualifications and the nature of the work to which they are admitted should be allowed to weld critical assembly units.

Preventive inspection of welding equipment by the department of the chief mechanic and power engineer should be carried out at least once a month.

The manufacture of steel welded structures should be carried out in accordance with the drawings and the assembly and welding process developed on their basis.

The surfaces of the parts at the location of the welds must be checked before welding. Edges to be welded must be dry. Traces of corrosion, dirt, oil and other contaminants are not allowed.

It is forbidden to strike an arc on the base metal, outside the boundaries of the seam, and to bring the crater to the base metal.

The deviation of the cross-sectional dimensions of the welds indicated in the drawings when welding in carbon dioxide must be in accordance with GOST 14771-76.

In appearance, the weld should have a uniform surface without sagging and sagging with a smooth transition to the base metal.

In resistance spot welding, the depth of indentation of the electrode in the base metal of the welding point should not exceed 20% of the thickness of the thin part, but not more than 0.4 mm.

The increase in the diameter of the contact surface of the electrode during welding should not exceed 10% of the size established by the technical process.

When assembling for spot welding, the gap between the contacting surfaces at the locations of the points should not exceed 0.5 ... 0.8 mm.

When welding stamped parts, the gap should not exceed 0.2 ... 0.3 mm.

When spot welding parts of different thicknesses, the welding mode should be set in accordance with the thickness of the thinner part.

After assembling the parts for welding, it is necessary to check the gaps between the parts. The size of the gaps must comply with GOST 14771-76.

The dimensions of the weld must comply with the drawing of the welded structure in accordance with GOST 14776-79.

In the process of assembly and welding of critical welded structures, step-by-step control should be carried out at all stages of their manufacture. The percentage of parameter control is specified by the technological process.

During the welding process, the sequence of operations established by the technical process, individual seams and the welding mode should be controlled.

After completion of welding, quality control of welded joints should be carried out by external inspection and measurements.

Fillet welds are allowed convex and concave, but in all cases, the leg of the seam should be considered the leg of an isosceles triangle inscribed in the section of the weld.

Inspection can be carried out without the use of a magnifying glass or using it with an increase of up to 10 times.

The control of the dimensions of welds, points and detected defects should be carried out with a measuring tool with a division value of 0.1 or special templates.

Correction of the defective section of the weld more than twice is not allowed.

External inspection and measurement of welded joints should be carried out in accordance with GOST 3242-79.

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