Specifications for a welded structure. 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, consumption of welding materials, electricity. Quality control methods.

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1. Technological section
1.6 Welding modes
Conclusion
List of references

1. Technological 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, rafter systems of industrial buildings, sports facilities. Also, this design can be used by specialists in the production of various types of pavilions, stage structures, awnings and podiums.

Principle of operation

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

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

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.

Designelementsandknotsfarms.

Truss elements are usually made of paired profiles. This allows them to be mated at the nodes 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 can always significantly reduce the weight of the trusses. The cross-section of the elements, the number of rivets, the length of the welded seams are determined by the strength calculation and depend on the load forces on the truss acting in the elements and on its span.

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

Lattice elements are usually designed with a T-shaped or cross-section from isosceles corners with dimensions from 60 x 60 mm to 80 x 80 mm. To simplify the production of work, it is desirable that all elements of the truss were selected from no more than 5 - 6 different profiles.

The truss belts, as a rule, have a length that significantly exceeds the maximum length of the rolled sections (12 - 15 m). In addition, at the plant it is impractical to manufacture entire trusses 20-30 m long, which would be inconvenient to transport to the construction site. Therefore, trusses are mostly made of 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 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 on the centers of gravity of the elements, and the rods of riveted trusses are centered along the rivet placement lines, called risks.

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

The name of the structure is a farm. Welded steel class - 17GS. The material of the rods is S345 steel, the gusset material is S345 steel.

Dimensions: Length - 24 m.;

Height - 3.7m .;

Width - 0.35 m.

The mass of the structure is 1952 kg.

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 a decrease in plasticity in the zones of welded joints;

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

Determination of the steel structure is carried out using the Scheffler diagram.

welded structure truss welding

The structure is welded from 17GS steel. The mechanical properties of 17GS steel are given in Table 1. The chemical composition of the welded material is shown in Table 2.

Table 1 - Mechanical properties of steels

Table 2 - Chemical composition of steel

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

Eq Cr \u003d% Cr +% Mo + 2% Ti + 2% Al +% Nb + 1.5% Si +% V \u003d

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

And then the equivalent nickel value is calculated:

Equiv Ni \u003d% Ni + 30% C + 30% N + 0.5Mn \u003d

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

According to the values \u200b\u200bof Eq Cr and Eq Ni on the Scheffler diagram (Figure 1), a point is drawn corresponding to the structure of the steel.

Figure 1 - Scheffler diagram

1.3 Specifications for the manufacture of a welded structure

The technical conditions for the manufacture of a welded structure provide for specifications for the main materials, welding consumables, as well as requirements for workpieces for assembly and welding, for welding and for quality control of welding.

As the main materials used for the manufacture of critical welded structures operating under dynamic loads, alloyed steels according to GOST 19281-89 or carbon steel of ordinary quality not lower than St3ps grade according to GOST 380-94 should be used.

The compliance of all welding consumables with the requirements of the standards must be confirmed by a certificate from the supplier plants, and in the absence of a certificate, by test data from the plant's laboratories.

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

The welding wire must be free from rust, oil and other contamination.

Requirements for workpieces for welding provide that the parts to be welded from sheet, shaped, section and other rolled products must be straightened before being assembled for welding.

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

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

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

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

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

Parts intended for resistance welding, at the joints, must be free of scale, oil, rust and other contaminants on both sides.

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

The specified requirements are provided by technological equipment and corresponding tolerances for assembled parts.

During assembly, a force fit is not allowed, which causes additional stresses in the metal.

The permissible displacement of the welded edges relative to each other and the size of the permissible gaps should be no more than the values \u200b\u200bset 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 gaps 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 seam length. It is prohibited to fill the enlarged gaps with pieces of metal or other materials.

Assembly for welding must ensure the linear dimensions of the finished assembly unit within the tolerances specified in Table 3, angular dimensions of 10 degrees of accuracy GOST 8908-81 in the absence of other requirements for accuracy in the drawings.

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

Tacking of welded structure elements during assembly should be performed using the same filler materials and requirements as when making welds.

The assembly for welding shall be approved by the Quality Department. When transporting and turning 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, unless the installation of instruments is not foreseen. The condition of the equipment should be checked daily by the welder and fitter.

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 fabrication of welded steel 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 a procedure for applying seams, in which the internal stresses and deformations in the welded joint will be the least. It should provide maximum weldability in the down position.

It is prohibited to carry out welding works by methods not specified in the technological process and this standard, without agreement with the chief welding specialist, deviation from the welding modes indicated in the technical process charts, the sequence of welding operations is not allowed.

The surfaces of the parts at the locations of the welds should be checked before welding. The edges to be welded must be dry. Traces of corrosion, dirt, oil and other contamination are not allowed.

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

In appearance, the weld seam 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 presentation of the product to the Quality Control Department, the welded seams and adjacent surfaces must be cleaned of slags, sagging, metal spatter, scale and checked by a welder.

In resistance spot welding, the depth of indentation of the electrode into the base metal of the welding spot 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 the welding process should not exceed 10% of the size established by the technological 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 resistance spot welding of parts of different thickness, 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 correspond to the drawing of the welded structure in accordance with GOST 14776-79.

During the assembly and welding of critical welded joints, operational control should be carried out at all stages of their manufacture. The percentage of parameters control is negotiated by the technological process.

Before welding, you should check the correctness of assembly, the size and quality of the tacks, the observance of 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 must be controlled.

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

Convex and concave fillet seams are allowed, but in all cases the leg of the seam should be considered the leg of an isosceles triangle inscribed in the seam section.

Inspection can be carried out without using a magnifying glass or using it with a magnification 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 graduation of 0.1 or special templates.

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

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

1.4 Definition of the type of production

The entire enterprise producing metal structures belongs to the serial production type.

Mass production is much more efficient than single production, because the equipment is used more fully, and the specialization of workplaces ensures labor productivity. Depending on the number of products in a batch and the value of the coefficient of fixing operations, small-batch, medium-batch and large-batch production are distinguished.

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

1.5 Selection and justification of assembly and welding methods

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

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 plates, assembly should be carried out only in those cases when welded structures of the same type, but different in size, are specified in the project. Simple welded structures can be assembled using templates.

In addition, assembly devices provide a reduction in assembly time and an increase in labor productivity, an easier working environment, an increase in the accuracy of work and an improvement in the quality of the finished welded structure.

The parts assembled for welding are fixed in fixtures and on stands with the help of 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 material to be welded;

length of welded seams;

requirements for the quality of products;

the chemical composition of the metal;

envisaged productivity;

cost of 1 kg of deposited metal;

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

manual arc welding;

semiautomatic gas-shielded welding;

automatic welding in shielded gases and submerged arc.

Manual arc welding (RDS) due to its low productivity and high labor intensity is not acceptable in serial and mass production. It is mainly used in one-off and small-batch production.

1.6 Welding modes

Welding mode is a set of characteristics of the welding process that ensure the receipt 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, speed of electrode movement along the seam (welding speed), type of current and polarity. With mechanized welding methods, one more parameter is added - the feed speed of the welding wire, and when welding in shielded gases - the specific consumption of shielding gas.

Welding 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 select the correct 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 seam are influenced not only by the basic 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 product, the stick out of the electrode, the structural form of the joint 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 to be welded, the wire grade, the flux, or the shielding gas, as well as the method of protection against the flow of molten metal are known. Therefore, before starting the calculation, the structural elements of a given welded joint should be installed in accordance with GOST 8713-79, or GOST 14771-76.

For fillet welds, the penetration depth can be taken:

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

1.7 Selection of welding consumables

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

ensuring the required operational strength of the welded joint, i.e. the 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 dimensions and the number of these defects per unit of weld length);

lack of hot cracks, i.e. obtaining a weld metal with sufficient technological strength;

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

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

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

The choice of steel wire for mechanized welding 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 workpieces to be welded	Electro type	Coating type electrode	Electrode brand	Note
Low carbon				DC welding
			UONI-13/45, SM-11	DC and AC current
Medium carbon				Constant current. It is used for welding non-critical structures
				Constant current. 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. Constant current

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

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


2, 3 and 4 - in all areas except 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 5-6 mm

The 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 choice of welding equipment is made. The main conditions for selection 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 for 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 welding semiautomatic devices, giving preference to equipment operating in a shielding gas environment with a power source - rectifiers.

We chooseRectifierweldingVD-313 intended for manual arc welding of steel products with covered electrodes at direct current. The welding current is infinitely regulated by mechanical movement of the horizontal magnetic shunt. The arc current of the welding rectifier VD-313 is calibrated on the outer surface of the shunt. The original shunt control mechanism dramatically reduces the time required to change the welding mode. Welding rectifier VD-313 is distinguished by simplicity, design reliability, 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 devices.

Figure 2 - RectifierweldingVD-313

TechnicalspecificationsrectifierweldingVD-313:

Supply voltage, V 3x380 Limits of regulation of welding current, A 60-315 Nominal welding current, A 315 Nominal operating mode with a welding cycle duration of 10 min., PN,% 60 Nominal operating voltage, V 32 Open circuit voltage, V, no more 70 Primary power, kVA, no more than 26 Weight, kg 95 Overall dimensions (LxWxH), mm 964x570x827

RectifierweldingVD-313:

Infinitely adjustable welding current Rejection of moving windings Forced cooling

there isrectifierblock (diodebridge) for this welding rectifier.

1.9 Determination of technical norms of time for assembly and welding

The total time for performing the welding operation T sv, hour, is determined by the formula:

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

t p. h. \u003d 10% t about \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 o \u003d 0.323 h.

Tw \u003d 4.613 + 0.413 + 0.377 + 0.323 + 0.33 \u003d 6.06 h.

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

The mass of the deposited metal is determined by the formula:

kg;

When semi-automatic welding flux consumption per product G f, 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 load

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

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

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

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

assembly: n-h;

welding: n-h;

locksmith: n-h.

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

We calculate the number of equipment С p according to the operations of the technical process:

accepted amount of equipment C n \u003d 1,1,1 pcs.

Calculation of the equipment load factor.

For each operation:

Average calculated:

1.12 Calculation of the number of employees

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

people;

we determine the number of auxiliary workers Р вр, according to the formula:

people;

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

people;

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

people;

We determine the number of specialists (technologists) P \u200b\u200bspecial, according to the formula:

people;

Determine the number of technical executors (timekeepers) P tech. isp., according to the formula:

people

Enter the calculation results in Table 16.

Table 5 - Number of employees

1.13 Equipment maintenance and operating costs

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

kWh;

1.14 Methods for dealing with welding deformations

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

When assembling structures, use, if possible, assembly devices (tie bars, wedges, etc.), ensuring free movement of the welded structures from shrinkage of the seams. Tacks can only be used for joints of thin metal parts (3-5 mm) and in lap joints. The dimensions of the blunts, gaps and alignment of the elements should be strictly observed.

Carry out the required sequence of welding seams; alternating layers of double-sided seam. Avoid exceeding the value of heat input into the seam (increasing the strength of the welding current in comparison with the recommended one for the type and diameter of electrodes used).

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

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

Use preliminary back bending of sheet metal parts.

When welding sheet tank structures (bottoms and housings), first weld the joints between the sheets, and then the joints between the strips or belts; in the reverse order, cracks may appear at the intersections of the seams, as well as an increase in the warpage of structures.

If necessary, apply pre-heating and auxiliary 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 with unacceptable distortion of the shape and size of structures.

Sometimes a combined thermomechanical method is used to eliminate the bulge. To do this, heat this bulge to a temperature of 700-800 ° C around the circumference, and then tap it evenly 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 eliminate the bulge.

1.15 Choice of quality control methods

Before use, welding consumables must be checked:

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

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

for damage to the packaging and materials themselves;

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

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

external examination with checking 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 seam length. 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.

Control of the dimensions of the welded seam and 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 seams. For external examination it is recommended to use a magnifying glass with 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 control.

The control of welded joints of structures by non-destructive methods should be carried out after correcting unacceptable defects detected by external inspection.

Selective inspection 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 examination, as well as areas of intersection of the seams. The length of the controlled area is at least 100 mm.

In the seams of welded joints of structures erected or operated in areas with a design temperature below minus 40 ° C to minus 65 ° C inclusive, internal defects are allowed, the equivalent area of \u200b\u200bwhich does not exceed half the values \u200b\u200bof the permissible 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 area.

In joints that can be welded from both sides, as well as in joints on backings, the total area of \u200b\u200bdefects (external, internal, or both) in the evaluated section should not exceed 5% of the longitudinal section of the weld in this section.

In joints without backings, accessible to welding only on one side, the total area of \u200b\u200ball defects in the evaluated section should not exceed 10% of the longitudinal section of the welded seam in this section.

Welded joints, controlled at negative ambient temperatures, should be dried by heating to completely remove the frozen water.

1.16 Safety, fire prevention and environmental protection

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, since the no-load voltage during arc manual welding reaches 80 V, and in plasma cutting and welding 200 V, the provision of safety standards consists in reliable insulation of current-carrying cables and reliable grounding of welding current sources. In order to avoid electric shock, the equipment should be equipped with automatic power cut-off systems in the event of an arc break. Likewise, the electrode holder must be insulated to prevent accidental contact with products and current-carrying devices. It is strictly forbidden to make contact with the terminals of high voltage circuits.

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

When cutting, splashes of molten metal appear, which is a danger to welding equipment. Consequently, it is not allowed to store any lubricants and flammable materials in the equipment locations. If a fire occurs, it may not be noticed immediately, therefore, at the end of the work, you should carefully inspect the place of work for a possible fire.

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

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

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

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

m 3 / h;

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

Lighting of the assembly and welding area

In assembly and welding shops, it is advisable to create a system of general lighting of localized or uniform general lighting using portable local lighting fixtures. Illumination levels for welding are set according to regulations for fluorescent lamps E cf \u003d 150 lx, for incandescent lamps E cf \u003d 50 lx.

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

Was chosen RectifierweldingVD-313that meets 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 load on production and increasing the annual program.

List of references

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

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

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

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

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 .-- 139s.

8. Browds M.E. Labor protection during welding in mechanical engineering - M .: Mechanical engineering, 1978. - 186 p.

9. Belov S.V., Brinza V.N. and other Safety of production processes: Handbook - M .: Mechanical engineering, 1985. - 448 p.

Posted on Allbest.ru

4. Manufacturability of production of welded structures

Optimal are constructive forms that correspond to the service purpose of the product, ensure reliable operation within a given resource, and make it possible to manufacture a product with minimal expenditure of materials, labor and time.

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

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

Special criteria are used to assess manufacturability.

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

where Тп - labor intensity according to the design option, standard-h; TB - labor intensity according to the basic version, norm-h.

Material efficiency... The assessment of the efficiency of using materials can be carried out according to the following indicators:

specific material consumption of the structure

material utilization rate

material usability factor

relative anm or specific Kum m consumption of deposited metal

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,%:

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.

Usually, it is sought to make welded joints so that they are equal in strength to the base material of the workpiece. In this case, you should choose well-weldable materials: 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.

Product Specifications (T.U.)

The main requirement for the product is to ensure operational reliability 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 tolerances of their assembly accuracy must comply with GOST 8713-79. “Submerged arc welding. Welded joints ”.

Specifications for the main and welding materials

Incoming stamped parts should not have dents, delamination, pores and various contaminants. The workpieces must be degreased before welding.

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

Flux specifications

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

Fluxes should be made in the form of homogeneous grains. The content of foreign particles (undissolved particles of raw materials, lining, coal, graphite, coke, metal particles, etc.) should be no more than: 0.5% by weight of the flux.

Working with fluxes during their sorting, packaging, transportation, quality control can be accompanied by the emission of dust containing manganese, silicon, fluoride compounds. Flux dust is chemically hazardous and harmful production factors... By the nature of the effect on the human body, flux dust is toxic, irritating and sensitizing, the way of penetration into the body is through the respiratory system, skin and mucous membranes.

The fluxes are accepted in batches. A batch should consist of one grade of flux and be issued with one quality document containing:

· Trademark or name and trademark of the manufacturer;

· Brand of flux;

· Batch number;

· Lot weight;

· Results of chemical analysis;

· Date of manufacture;

· Designation of this standard.

The mass of the batch should be no more than 80 tons.

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

The granulometric composition of the fluxes is determined by sieving a sample on a device of grade 029M, made according to regulatory and technical documentation, through the corresponding two sieves with a diameter of 200 mm for (60 ± 5) s and subsequent weighing the residue on a large sieve and sieving under a fine sieve with an error of no more than 0 ,1 %.

Each bag or container is labeled or marked with waterproof paint indicating:

manufacturer's trademark or name and trademark;

· Brand of flux;

· Net weight;

· Batch number;

· Designation of this standard;

· Handling sign “Keep away from moisture”.

The flux must be transported in covered vehicles by any type of transport in accordance with the rules of transportation, loading and fastening 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 the preparation of the edges, the parts must have a surface without pores, cavities, nicks, burrs, notches and dents.

b) Preparation of the edges of the blanks should ensure the possibility of careful 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 in the drawing (see graph. part).

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

Welding specifications

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

Weld after assembly quality control.

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

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

The use of cooling and clamping equipment in welding improves the metal structure, mechanical and corrosion properties of the joint. Before welding, degrease the weld seam area at a distance of 45 mm with a napkin (GOST 11680-76) moistened with acetone (GOST 2768-69), as well as the spacer, lead plates, copper surfaces of the linings, the top and adjacent surfaces. Check the joint gaps no more than 0.2 mm. The spacer must be tacked at 4 points and the outlet plates along the entire height using ArDES and then check the quality of the tacks. The cleaning of the spacers tacks is carried out with a metal brush to a metallic shine and degreasing with a napkin moistened with acetone. Before welding, it is necessary to mark the axis of the weld seam on the output 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 for a 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 a permissible fluctuation of the supply voltage of the electric current not exceeding ± 5% of the nominal. After the weld seam has cooled down (until the seam darkens), turn off the argon gas, after which the welded parts are held 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 reference samples is carried out without readjustment of GSPD-1M.

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

Welding work must be carried out in compliance with safety requirements.

Material description

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

Table 1 - Chemical composition of 09G2S steel

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 allows the production of complex structures from sheet metal of this brand for the chemical, oil, construction, shipbuilding and other industries. Using quenching and tempering, high-quality pipeline fittings are produced. High mechanical resistance to low temperatures also makes it possible to successfully use pipes from 09G2S in the north of the country.

Also, the brand is widely used for welded structures. Welding can be carried out both without heating and with preheating to 100-120 C. Since there is little carbon in steel, its welding is quite simple, and the steel is not hardened or overheated during the welding process, due to which there is no decrease in plastic properties or an increase in its graininess. 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, which are worse cooked 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 the welding is performed without cutting edges. When using multi-layer welding, cascade welding is used with a current of 40-50 Amperes per 1 mm of the electrode to prevent overheating of the weld. After welding, it is recommended to warm up the product to 650 C, then hold it at the same temperature for 1 hour for every 25 mm of rolled thickness, after which the product is cooled in air or in hot water - due to this, the seam hardness in the welded product increases and tension zones are eliminated.

For welding under a layer of flux of steel 09G2S when operating at least -40 ° C, it is recommended to use Sv-08GA welding wire. An AN-348A flux is used as fluxes for single-arc welding.

Technical part

MINISTRY OF EDUCATION OF THE REPUBLIC OF BELARUS

BOBRUISK STATE MACHINE BUILDING

PROFESSIONAL TECHNICAL COLLEGE

Specialty 2-36 01 06 Equipment and

welding technology

Specialization 2 - 36 01 06 02 Production of welded

constructions

Technician qualification

AGREED APPROVED

cyclic commission of special disciplines Deputy. Director for PM

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

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

INSTRUCTIONS

to implement

graduation project

Developed by teachers special. disciplines

N.M. Rogomantseva

K. D. Yukhnevich

engineering graphics teacher

YES. Melnikov.

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 Justification of the material of the welded structure 6

1.3 Specifications for the manufacture of welded structures 7

1.4 Definition of production type 11

1.5 Selection and justification of assembly and welding methods 12

1.6 Welding modes 15

1.7 Selection of consumables 20

1.8 Selection of welding equipment, technological equipment,

tool 21

1.9 Determination of technical standards of time for assembly and welding 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 operating costs 32

1.14 Methods for dealing with welding deformations 33

1.15 Choice of quality control methods 33

2 Design Section 34

2.1 Column design description 34

2.2 Selection and justification of the metal of the welded structure 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 strips 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 quality control methods for welded

connections 43

2.9 Selecting welding modes and welding equipment 43

3 Section of labor protection 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. Specification for welded structure

Appendix B. Specification for assembly and tacking device

GENERAL PROVISIONS, COMPOSITION AND CONTENT

DIPLOMA PROJECT

The diploma project is a complex independent creative work carried out at the final stage of training, during which the student solves specific professional tasks corresponding to the level of education of the assigned qualification, on the basis of which the State Qualification Commission decides on awarding the student with the qualification of a specialist.

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

The topic of diploma 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 with a certain volume of its production per year. The technological process must correspond to the modern level of the relevant industry.

When using factory basic, welding and auxiliary materials, the 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 diploma projects should be considered at a meeting of the cyclic commission and approved by the Deputy Director for Academic Affairs.

Responsibility for making a decision in the diploma project, the quality of the execution of the explanatory note, graphic part, a set of documents for the technological process, as well as for the timely completion of the work is borne by the author-student and the leader.

INTRODUCTION

In the introduction, it is required to briefly outline 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 TECHNOLOGY SECTION

1.1 Description of the welded structure, its purpose

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

1.2 Substantiation 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 costs of its manufacture, taking into account the maximum savings in metal;

Guaranteeing conditions for good weldability with minimal softening and a decrease in ductility in the zones of welded joints;

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

Specify the mechanical properties and chemical composition of the material to be welded.

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

where C e - carbon equivalent,%;

Carbon content,%;

Magnesium content,%;

Nickel content,%;

Chromium content,%;

Molybdenum content,%;

Vanadium content,%.

Steel for which C e \u003d 0.2 ... 0.45% weld well, 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

Ultimate 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

The technical conditions for the manufacture of a welded structure provide for specifications for the main materials, welding consumables, as well as requirements for workpieces for assembly and welding, for welding and for quality control of welding.

Students must take technical conditions for the manufacture of welded structures at factories in the OGS or in 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, alloyed steels according to GOST 19281-89 or carbonaceous steels of ordinary quality not lower than St3ps grade according to GOST 380-94 should be used. For irresponsible welded structures, steels of at least St3ps grade in accordance with GOST 380-94 should be used.

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

In manual arc welding, electrodes of at least E42A type 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.

The welding wire must be free from rust, oil and other contamination.

1.3.3 Requirements for workpieces for welding provide that the parts to be welded from sheet, shaped, section and other rolled products must be straightened before being assembled for welding.

After rolling or bending, the parts must be free of cracks and burrs, tears, waviness and other defects.

The edges of parts cut with scissors must not have cracks or burrs. The cut edge must be perpendicular to the surface of the part. The permissible 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 the parts should be indicated in the drawings and technological processes.

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

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

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

Parts intended for resistance welding, at the joints, must be free of scale, oil, rust and other contaminants on both sides.

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

The specified requirements are provided by technological equipment and corresponding tolerances for assembled parts.

During assembly, a force fit is not allowed, which causes additional stresses in the metal.

The permissible displacement of the welded edges relative to each other and the size of the permissible gaps should be no more than the values \u200b\u200bset 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 gaps 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 seam length. It is prohibited to fill the enlarged gaps with pieces of metal or other materials.

The assembly for welding must provide 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 section of the tacks is allowed up to half the section of the weld. Tacks should be placed at the locations of the welded seams. The applied tacks must be cleaned of slag.

Tacking of welded structure elements during assembly should be performed using the same filler materials and requirements as when making welds.

The sizes of the tacks should be indicated in the technological process cards.

The assembly for welding shall be approved by the Quality Department. When transporting and turning 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 admitted should be allowed to weld critical assembly units.

Welding equipment must be provided with voltmeters, ammeters and pressure gauges, unless the installation of instruments is not foreseen. The condition of the equipment should be checked daily by the welder and fitter.

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

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

The technological process of welding should provide for such a procedure for applying seams, in which the internal stresses and deformations in the welded joint will be the least. It should provide maximum weldability in the down position.

It is prohibited to carry out welding works by methods not specified in the technological process and this standard, without agreement with the chief welding specialist, deviation from the welding modes indicated in the technical process charts, the sequence of welding operations is not allowed.

The surfaces of the parts at the locations of the welds should be checked before welding. The edges to be welded must be dry. Traces of corrosion, dirt, oil and other contamination are not allowed.

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

The deviation of the dimensions of the cross-section of the welded seams specified in the drawings when welding in carbon dioxide must be in accordance with GOST 14771-76.

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

At the end of welding, before the presentation of the product to the Quality Control Department, the welded seams and adjacent surfaces must be cleaned of slags, sagging, metal spatter, scale and checked by a welder.

In resistance spot welding, the depth of indentation of the electrode into the base metal of the welding spot 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 the welding process should not exceed 10% of the size established by the technological 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 resistance spot welding of parts of different thickness, 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 correspond to 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, operational control should be carried out at all stages of their manufacture. The percentage of parameters control is negotiated by the technological process.

Before welding, you should check the correctness of assembly, the size and quality of the tacks, the observance of 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 must be controlled.

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

Convex and concave fillet seams are allowed, but in all cases the leg of the seam should be considered the leg of an isosceles triangle inscribed in the seam section.

Inspection can be carried out without using a magnifying glass or using it with a magnification 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 graduation of 0.1 or special templates.

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

External examination 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 attributed to one of three types of production:

Single;

Serial;

Massive.

Individual 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 welding production, there is almost no special welding equipment, assembly and welding devices and mechanisms.

Serial production is characterized by a limited range of manufactured products and a large production volume, 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 workstations. A relatively stable range of products allows the widespread use of special assembly and welding devices, the introduction of automated welding methods, and the organization of production lines in some areas. In this case, both general shop transport and floor transport are used. The specialization of certain types of work requires highly skilled workers.

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

Mass production is much more efficient than single production, because the equipment is used more fully, and the specialization of workplaces ensures labor productivity. Depending on the number of products in a batch and the value of the coefficient of fixing operations, small-batch, medium-batch and large-batch production are distinguished.

Mass production is characterized by continuous production of a narrow range of products over a long period of time and a large production volume. It allows the widespread use of special high-performance equipment and fixtures. This ensures high labor productivity, better use of fixed assets and lower production costs than in batch and single-piece production.

Based on the mass and dimensions of the welded structure, as well as the set 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 production program (pcs) and product weight

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

1.5 Selection and justification of assembly methods and welding

1.5.1 The assembly of welded structures in a 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 performing welded seams.

In the conditions of serial and mass production, the assembly for welding should be carried out on special assembly stands or in special assembly and welding devices that ensure the required relative position of the parts included in the welded structure and the accuracy of the assembly of the welded structure to be produced in accordance with the requirements of the drawing and technical specifications for the assembly.

In addition, assembly devices provide a reduction in assembly time and an increase in labor productivity, an easier working environment, an increase in the accuracy of work and an improvement in the quality of the finished welded structure.

The parts assembled for welding are fixed in fixtures and on stands with the help of 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;

Length of welded seams;

Requirements for the quality of products;

The chemical composition of the metal;

Envisaged performance;

Cost of 1 kg of deposited metal;

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

Manual arc welding;

Gas-shielded mechanical welding;

Automated gas-shielded and submerged-arc welding.

Manual arc welding (RDS) due to its low productivity and high labor intensity is not acceptable in serial and mass production. It is mainly used in make-to-order production.

It is most advisable to use mechanized welding methods.

One of such 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.

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

A small volume of slags 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 price of 1 kg of weld metal in carbon dioxide welding is always lower than in gas and manual arc welding.

When welding in carbon dioxide with a wire of 0.8-1.4 mm in diameter, 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 machines - 1.8-3 times higher than with manual arc welding.

When welding in carbon dioxide with a wire with a diameter of 0.8-1.4 mm, 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, productivity is 1.5- 2.5 times higher than manual electric 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 joint, the quality of assembly, etc. At the same time, the productivity is only 1.1-1 .8 times higher than manual.

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 make long seams on metal of medium and large thicknesses, it is advisable to use automatic submerged arc welding. In submerged arc welding, the stick out is significantly less than in manual arc welding. Therefore, it is possible, without fear of overheating of the electrode and the separation of the protective coating, several times to increase the strength of the welding current, which makes it possible to dramatically increase the productivity of welding, which is 5-20 times higher than in manual arc welding, the deposition rate 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 insulates them from the environment. The flux contributes to the production of a clean and dense weld metal, without pores and slag inclusions, with high mechanical properties The introduction of stabilizing elements into the flux and a high current density in the electrode allows welding metal of considerable thickness without cutting edges. There are practically no losses for waste and electrode metal spatter. The welding process is almost completely mechanized. Mechanized submerged-arc welding in comparison with RDS significantly improves the working conditions of the welder-operator, increases the general level and culture of production.

Currently on machine-building enterprises In the Republic of Belarus, more and more work is underway to introduce welding in argon mixed with carbon dioxide into production. When welding in CO 2 with wires of any diameter, two types of transfer of molten metal, characteristic of optimal modes, are revealed: with periodic closures of the arc gap and drop transfer without short circuits. When welding in a mixture of Ar + CQ 2, the range 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: spraying and spraying of metal on the welding of the part and the nozzle.

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

When welding in CO 2, there is a range of modes in which an increase in nozzle spatter is observed. For a wire with a diameter of 1.2 mm, this area is 240-270 A, and for a wire diameter of 1.6 mm, it is 290-310 A. When welding in a mixture of argon and carbon dioxide, the area of \u200b\u200blarge spatter modes is practically absent. If the nozzle splashes, the gas shielding condition will deteriorate and periodic cleaning will reduce performance. The shape of the penetration when welding CO 2 is round and remains in the Ar + CO 2 mixture at low currents. At high currents, a protrusion appears in the lower part of the penetration, increasing the penetration depth, which increases the fracture area along the fusion zone. With an equal penetration depth, the penetration area of \u200b\u200bthe base metal in the Ar + CO 2 mixture is 8-25% less than when welding in CO 2, which leads to a decrease in deformation. Along with welding in a mixture of argon and carbon dioxide, welding in a mixture of carbon dioxide and oxygen is most widely used. The presence of oxygen in the mixture in the range of 20-30% reduces the surface tension forces, which promotes finer droplet transfer and more “stable” rupture of the bridge between the drop and the electrode, which reduces spattering. In addition, the oxidized drop is less welded to the metal. Oxidized reactions increase the amount of heat generated in the arc zone, which improves welding productivity. Welding in a mixture of CO 2 + O 2 has the greatest advantages with an increased stick out of the electrode and the use of wires doped with zirconium, for example Sv08G2STs.

Semi-automatic welding in a mixture of CO 2 + O 2 is carried out with wires 1.2-1.6 mm in diameter with wires of the Sv08G2S and Sv08G2SC brands with the usual electrode stickout in all spatial positions.

1.6 Welding modes

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

The calculation of the welding mode is always carried out for a specific case, when the type of connection, 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, the structural elements of a given welded joint should be installed in accordance with GOST 8713-79. It should be borne in mind that the maximum cross-section of a single-pass seam made by an automatic machine should not exceed 100 mm 2.

For butt joints, the cross-sectional area of \u200b\u200bthe seam Аш, mm 2 is determined by the formula

Ash \u003d 0.75eg + sb, (1.2)

where Аш is the seam cross-sectional area, mm 2;

e - seam width, mm;

g - seam reinforcement, mm;

s - seam thickness, mm;

b - gap, mm.

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

I \u003d (80 ... 100) h, (1.3)

where I is the strength of the welded 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 \u003d (0.7 ... 0.8) S, (1.4)

where h - penetration depth, mm;

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

, (1.5)

where h - penetration depth, mm;

S - 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 it is specified 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 wire diameter.

The 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 - 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 using the empirical formula

11.6 ± 0.4 g / Ah (1.8)

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

, (1.9)

where is the deposition rate, g / Ah;

A and B are coefficients, the values \u200b\u200bof which for AN-384A flux are given in Table 1.6.

Table 1.6 - Values \u200b\u200bof coefficients А and В for flux АН-384А

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

, (1.10)

where Vpod - wire feed speed, m / h;

Аш - sectional area of \u200b\u200bthe seam, mm 2;

Ae is the area of \u200b\u200bthe seed of the electrode wire, mm 2;

Vw - 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 is the feed speed of the electrode wire, m / h

αн - surfacing coefficient, g / Ah;

I - welding current, A;

d is the diameter of the welding wire, 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 Аш - cross-sectional area, mm

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

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

k - seam leg, mm.

We set the number of passes based on the fact that no more than 100 mm 2 of the seam area can be welded in one pass automatically.

We select the diameter of the electrode, bearing in mind that fillet welds with a 3-4 mm leg 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. Do not use welding wires with a diameter greater than 5 mm, as it does not provide root penetration.

For the adopted 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 - welding current strength, 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 surfacing area in one pass, the welding current and the deposition coefficient, determine the welding speed VW, m / h according to the formula (1.7).

The feed speed of the electrode wire is determined by the formula (1.10).

1.6.3 The choice of the 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 on the basis of generalized experimental data.

1.7 Selection of welding consumables

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

Ensuring the required operational strength of the welded joint, i.e. the 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 of weld length);

No hot cracks, i.e. obtaining a weld metal with sufficient technological strength;

Obtaining a set of special properties of metal, seam (heat resistance, heat resistance, corrosion resistance).

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

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

In the cards of the technological process for each technological operation (assembly on tacks, welding), it is necessary to indicate the types, grades, standard for types and grades, welding materials.

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 - 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 by 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 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 according to GOST 9078-81, which provides for two groups of fluxes:

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

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

Inert gases (argon, helium) and active gases (carbon dioxide, hydrogen) are used as shielding gases in 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 types of gaseous helium: high-purity helium (99.98% He) and technical helium (99.8% He).

Carbon dioxide intended for welding complies with GOST 8050-85, which, depending on the CO2 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 justifying the choice of welding materials for the welding methods adopted in the project, it is necessary to give in the form of tables 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,

instrument

In accordance with the established technological process, the choice of welding equipment is made. The main conditions for selection are:

The technical characteristics of the welding equipment in accordance with the adopted technology;

Smallest dimensions and weight;

Highest efficiency and lowest power consumption;

Minimum cost.

The main condition for 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 welding semiautomatic devices, giving preference to equipment operating in a shielding gas environment with a power source - rectifiers.

To select rational types of equipment, you should use the latest data from reference and information literature, catalogs and brochures on welding equipment, which contain technical characteristics of power sources, welding semiautomatic devices and automatic machines.

When determining the consumption of electricity, its consumption should be carried out 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 machine.

The selection and design of assembly and welding devices (equipment) is carried out in accordance with previously selected methods of assembly and welding of units. When developing this issue, it is necessary to take into account the fact that the choice of assembly and welding devices should ensure the following:

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

Facilitation of working conditions;

Improving the accuracy of work, improving the quality of products, maintaining the specified shape of the welded products by appropriate fixing them to reduce deformations during welding.

Fixtures must meet the following requirements:

Provide accessibility to the places of installation of parts to the handles of clamping and fixing devices, to the places of stuck and welding;

Provide 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;

Provide such positions of products in which there would be the smallest number of turns, both when applying tack welds and when welding;

Provide free access when checking the product;

Ensure the safe performance of assembly and welding work.

In serial production, the device should be chosen based on the possibilities of restructuring production for a new type of product, i.e. universal.

The type of fixture must be selected depending on the program, product design, technology and degree of precision 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 specifications for the manufacture of a welded structure.

1.9 Determination of technical norms of time for assembly and welding

The total time to complete the welding operation Tsw, 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;

tо - main time;

t in - auxiliary time;

t obs - time to service the workplace;

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

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

where is the main time, hour;

Surfacing coefficient, g / A · hour;

I sv - welding current strength, A;

Deposition metal mass, g.

The sum of the lengths of all seams, see.

The calculated main 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 assignment, instructing, receiving and handing over the tool, inspection and preparation of 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 the term paper we will accept:

t p.c. \u003d 10% of t о.

The auxiliary time includes the time for refueling the cassette with the electrode wire t e, inspection and cleaning of the welded edges t cr, cleaning the seams from slag and splashes t br, branding the seams t cl, installing and rotating 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 for refueling the cassette from the electrode wire, min;
t cr - time for inspection and cleaning of the welded edges, min;

t br - time for cleaning 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 fixing, min;

In automatic welding, the auxiliary time includes the time for threading the cassette with the electrode wire. This time can be taken equal to t e \u003d 5 min.

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

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

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

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

L w - seam length in meters.

The time for the installation of the mark, t cl is taken as 0.03 min per 1 character

The time for installation, rotation and removal of the product, t ed, depends on its mass (table 1.7).

Table 1.7 - Norm of time for installation, rotation and removal of the product depending on its weight

The time for servicing the workplace includes the time for setting the welding mode, setting up the machine, cleaning the tool, etc. we take equal to:

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

where t obs is the time for servicing the workplace, hour;

Main time, hour.

Rest breaks and personal needs depend on the position in which the welder is performing the work. When welding in a comfortable position t p \u003d 0.07 · t about.

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

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

where is the mass of the deposited metal, g;

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

Density of metal, 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 an 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 during the welding process for waste and spatter, in the form of an electrode coating.

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

G el \u003d ψ M ΣНМ, (1.23)

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

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

М ΣНМ - mass of deposited metal.

The ψ values \u200b\u200bfor various types and brands of electrodes are indicated in the literature or table 1.8 of this methodological manual.

Wire consumption for 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;

Weld metal weight, kg;

Wire loss factor.

Table 1.8 - Flow coefficient ψ at different ways welding

Welding methods
Manual arc welding with electrodes grades:
VSC-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, VSC-2, TsL-11 UT-15, TsT-17 OZA-1, OZA-2
Automatic submerged arc welding 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 50% gas mixtures (Ar + CO 2)

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

The flux consumption for the product G f, kg is determined by the formula:

G f \u003d ψ f G pr, (1.25)

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

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

Table 1.9 - Coefficient of consumption ψ f in submerged arc welding

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

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

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

In semi-automatic welding, the flux consumption for the product G f, kg, is determined by the formula:

G f \u003d (1.2 ... 1.4) · М ΣНМ, (1.27)

where G f - flux consumption per product, kg;

Weld metal weight, kg

Carbon dioxide consumption 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 is the mass of the wire consumed, kg.

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

W \u003d a e M NM, (1.29)

where W is the power consumption, kWh;

М НМ - mass of deposited metal of one meter of weld, kg;

a e - specific power 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

With multi-station direct current welding, kWh / kt 6 ... 8

With automatic direct current welding, kWh / kg 5 ... 8

Under a layer of flux, 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 load

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

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

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

where F d is the actual fund of equipment operation time, 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 is reduced before the holidays (t c \u003d 1 hour);

К by \u003d 0.95 - coefficient taking into account equipment downtime in repair;

K s - the number of shifts.

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

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

IN - annual program, PCS.

The results of the calculations are summarized in Table 1.11.

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

We calculate the number of equipment С p according to the operations of the technical process:

where C p is the number of equipment for the operations of the technical process, pcs;

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

F d - actual fund of equipment operation time, h;

K n - coefficient of fulfillment of norms (K n \u003d 1.1 ... 1.2).

Т \u003d ΣТ pcs В, (1.33)

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

В - annual program, pcs.

The accepted amount of equipment, C p, is determined by rounding the estimated amount upward 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 - the number of equipment for the operations of the technical process, pcs;

С п - accepted amount of equipment, pcs.

Average calculated:

where is the average equipment load factor;

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

Total accepted number of equipment, pcs.

It is necessary to strive to ensure that the average equipment utilization factor is as close to one as possible. In mass production, its value should be at least 0.75 ... 0.85, and in mass-flow and large-scale production - 0.85 ... 0.76, in unit production - 0.8 ... 0.9 with two-shift work of shops.

1.12 Calculation of the number of employees

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

, (1.36)

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

T year is the annual workload of the program for operations, n-h;

Ф ДР - actual annual fund of working time of one worker, h;

К в - coefficient of performance standards of production (1.1 ... 1.3).

T year \u003d T pcs В, (1.37)

where T year is the annual workload of the program for operations, n-h;

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

В - annual program, pcs.

Ф ДР \u003d Ф Д / К с, (1.38)

where Ф ДР - the actual annual fund of working time of one worker, h;

F D - the actual fund of equipment operation time;

K s - the number of shifts.

The number of workers is rounded to the nearest whole number, taking into account the number of equipment.

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

Determine the number of auxiliary workers Р вр, according to the formula:

, (1.39)

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

Determine the number of employees Psl, according to the formula:

where R sl is the number of employees, people;

Р вр - the number of auxiliary workers, people;

R o.r. - the total number of main workers, people.

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

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

We determine the number of specialists (technologists) P \u200b\u200bspecial, according to the formula:

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

Rsl - the number of employees, people.

Determine the number of technical executors (timekeepers) P tech. , according to the formula:

, (1.43)

where P technical test. - the number of technical executors (timekeepers), people;

Rsl - the number of employees, people.

Enter the calculation results in table 1.12.

Table 1.12 - Number of employees

1.13 Equipment maintenance and operating costs

The cost of power energy 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 is the actual annual fund of equipment operation time, 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 is the efficiency of electric motors (0.8 ... 0.9).

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

R squeeze \u003d R h · S about · P c · T pcs about. / 60, (1.45)

where P comp is the compressed air consumption per unit of the product, when compressed air is used, m 3;

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

With 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 devices, pcs.,

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

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

For pneumatic hoists P h \u003d 0.1 ... 0.4 m 3.

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

1.14 Methods for dealing with welding deformations

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

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

1.15 Choice of quality control methods

Indicate what quality control methods are used depending on the nature and purpose of the structure, the degree of its responsibility, the design of welded seams and the grade of the welded material (external inspection of welded seams, 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, its working conditions. To do this, study the literature,,.

2.2 Selection and justification of the welded column metal

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

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

A guaranteed condition for good weldability with minimal softening and a decrease in plasticity in the zones of welded joints;

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

Having substantiated the choice of steel grade, it is necessary to indicate the chemical composition and mechanical properties of the 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

Roughly we take the coefficient of longitudinal bending

Determine the required cross-sectional area of \u200b\u200bthe column bar A tr, cm 2

(1)

where N - load calculation, kN

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

Since the column section 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;

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 bar about the x-x axis, l x

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

r x - radius of gyration, see

By l x we \u200b\u200bdetermine the actual value of the buckling coefficient j d.

Checking the column bar for stability s, kN / cm 2

(5)

where y with - coefficient of working conditions.

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

2.4 Calculation of the design of connecting strips

Determine the distance I in between the connecting strips 2 in accordance with Figure 2, see.

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

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

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

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

For this, from the condition of equilibrium

(7)

We express the flexibility of the rod about the y-y, l y

Determine the required radius of inertia of the section of the bar r ¢ y relative to the y-y axis, see.

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

If the shelves of the channel are located outward in accordance with Figure 3

Calculated dimensions (b) are rounded to an even whole number.

Determine the geometric characteristics of the bar section.

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

(12)

If the shelves of the channel are located inward, then a, cm 4

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

Determine the actual value of the radius of gyration of the section of the rod relative to the y-y, r² y, see.

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

Determine the reduced flexibility of the rod, l pr

(17)

If l pr £ l x, then the cross-section of the bar is selected correctly and the bar 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 bar for stability.

We determine the conditional shear force F conv, kN, arising in the section of the bar as a consequence of the bending moment.

For steels with s v up to 330 MPa

F conv \u003d 0.2 * A d (18)

For steels with s v up to 440 MPa

F conv \u003d 0.3 * A d (19)

Determine the force T, shearing the bar, provided that the bars are located on both sides, kN

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

We accept the dimensions of the slats.

Plank height d pl, cm.

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

Plank thickness S pl, cm.

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

2.5 Calculation of welds attaching the strips to the branches of the column

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)

K f - leg of the weld, cm (K f \u003d (0.6 ... 0.8) S pl), cm;

I w - the length of the welded seam attaching the bar to the column bar, cm (I w \u003d d pl + 2I w), see

Determine the shear stress in the weld, kN / cm 2

where A w is the cross-sectional area of \u200b\u200bthe weld, cm 2

Determine the resultant voltage 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 bearing area 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, it is reinforced with stiffening ribs. Anchor bolts fix the correct position of the column relative to the foundation.

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

where N is the calculated reinforcement in the column, kN;

R cm 6 - design resistance of concrete (foundation) for crushing,

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

Determine the width of the base plate B, cm

B \u003d h + 2S TP 2C (27)

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

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

C - cantilever part of the base plate, cm

C \u003d 10 ... 15 cm.

The final size B d is taken 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 section design.

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 her bending.

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

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

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

Determine the bending moment M 2 in section 2, resting on four sides, kN × cm

М 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 slabs supported on four sides

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 non-fixed side h - table 4.

Table 4 - Coefficient for calculating slabs supported on three sides

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

(34)

The diameters of the anchor bolts should be taken constructively:

For hinged bases d \u003d 20 ... 30 mm.

For rigid bases d \u003d 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.

Thickness of anchor tiles S а \u003d 30 ... 40 mm.

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

b а \u003d 2,2d + (10 ... 20) (35)

{!LANG-046b7c289a14f3b5b667050ff78847e5!}

(36)

{!LANG-8a977899225a38ed17f088ba568cf7ce!}

{!LANG-b21fe6fefadde8235fc2942ea0fa60bb!}

{!LANG-4f74c3538b527144a169d1dd2b66068f!}

{!LANG-46b0335290766fbd4a0d36f3bbd9ca19!}

{!LANG-805f30525efcb9cae86c770354b7acf6!}

{!LANG-c9e90cf0bc37351cbbd7174d98fc03f2!}

{!LANG-72258a5d2e61ba7b43bec7fd3d03149d!}

{!LANG-53e48d49632151055000cd2324bbcc66!}

{!LANG-0eb00b5413614f5eac0900d8074f0a6a!}

{!LANG-c8f205c3f02948d554c270d125a970cb!}

{!LANG-5680ba2c2705a3cae191331ce1df67fe!}

{!LANG-c0e2cf497767fda94313aaec602f2429!}

{!LANG-ad755fd5cf96002dc62173a7eb3777d5!}

(38)

{!LANG-8a977899225a38ed17f088ba568cf7ce!}

{!LANG-4aefbf8139544875ea0a6126ef4318a5!}

{!LANG-3f4d8d1cec6b60d9ce014f661b934b94!}

{!LANG-da149bdb6e1893e0d74166dbbf51e425!}

{!LANG-011ec7f6c4460462014753d6948db316!}

{!LANG-3f9af9efd66bfba3b0ab5d649524cb29!}

2. 8 {!LANG-7c397e62b8399b2d94ac729ef4248435!}

{!LANG-2767742471851c6dc8fab9e4c7a3d6ae!}

2. 9 {!LANG-e488f33b2168cf75abe9be50e6bbe92f!}

{!LANG-7d0507cc02df3905f20c539031ca6b1e!}

{!LANG-77c5003062edb4f36994f5337f73cada!} {!LANG-5d8f343a060d2d7627d6f52750d0986c!}{!LANG-af2636c7cb812b48f7acfc2f0a6d6f4c!}

{!LANG-1c691eeca78916cbefda5a5f10791485!}

{!LANG-444544925ba88b9cf0feaf03d846f045!}

{!LANG-eff1da1edb9d8f40e541ebb5b75abbbd!}

{!LANG-b8448f7363a89991d5f47048cb67f89a!}

{!LANG-21e50e07c681d4b6ae336f07f513a3b1!}

{!LANG-ddc6ada3c07f1d3818f456396168fb80!}

{!LANG-a732d8c4a76bf9921912f8202b5e2e65!}

{!LANG-f4fbe8a635332ec2d3be175591d0399f!}

(42)

{!LANG-f1b2b95bde8095eb0bfb47a1b9c310d5!}

{!LANG-86eff31d920ec3aeb66d166e4f864caa!}

{!LANG-6446821dddd51b26ab306769e20f485c!}

{!LANG-df6c6136beebf1cf1bd1776a4550cfb3!}

(44)

{!LANG-80308ad3291efb751c369abd3ae0428c!}

{!LANG-d8a6d7d7e409579477b9ac900ea5d702!} {!LANG-5993ad8202c113f4b1c1c76612b30c63!}{!LANG-71c2cb20cf6c54e242fb249f58672a17!}

{!LANG-d8dc2e9b113f6461123cf7a6875819f9!}

{!LANG-aff827a98e7b06e7bbfeaf9fcf1d009e!}

{!LANG-948ea26fef37700f257e4234d5419ad7!}

{!LANG-1a2eb20edcbabddb536aaa65ef417a30!}

{!LANG-dd5cb15a23f767cd05c1060c8b4af052!}

{!LANG-2d308a31ec6403cdf9549af10720e399!}

{!LANG-b1a98be7a5fd353810a900fc46b1d931!}

{!LANG-5ee34a3ecfb32ff49611b2b53c76a5c7!}

{!LANG-5c17d707be6e46199380af9f1fbe34c2!}

{!LANG-0d1cd14892db73fb727bf9c1498ca93d!}

{!LANG-51d4cfc576e04cf2b5b094eff231a38c!}

{!LANG-4fa9493e4e22165b6bc13f9835dcdeb9!}

{!LANG-725c470ec6df83484fb44572b2cb789e!}

{!LANG-953c025a50e1b08e98c95292647ad994!}

{!LANG-a8ea277c6c91f4a92b6431b5cdaf1215!}

{!LANG-386e2aa51269e166e87ce20f5191c218!}

{!LANG-b1625ded57ff195d69a04965c3a01640!}

{!LANG-50f7bc9c799dcddd8767c348bf1ce3f9!}

{!LANG-6ce9619e2ba1ed02de84a5a63c6fc9bd!}

{!LANG-683cc376d600542b2256ce2c78ed45d9!}

{!LANG-adbc1e13070cb4c64ee8e1c64f4c8005!}

{!LANG-169fcee9bfd8e5c77a107162fe646d83!}

, (2.1)

{!LANG-31e930a28e3a9740ebed68b526a4fb03!}

{!LANG-2a5ec3db5e67ff31532c42ba4116e841!}

{!LANG-a86c30106a801285f927ed526057508b!}

{!LANG-dbe59b108212de6243152c7f09e93b6b!}

{!LANG-e52f8f091a62b3f5b51ac87235301625!}

{!LANG-ed7d36d9c3b046b190ca57119d23b5dd!}

{!LANG-3f94fcdd9acc8cde3c5379097b637cc6!}

{!LANG-3d49a0a1ee44a003ccab85d0d28963ba!}

{!LANG-ec4d7685c17c9e727550751539ae8c25!}

{!LANG-e816625562e8ed24b5434f3174f15e70!}

{!LANG-ac0d66fab5f12598da249878f651fa54!}

{!LANG-73fc5c0b9a5fd2af19eb3eef0725af16!}

{!LANG-745fda3bb758b5101c3be9c12465108d!}

{!LANG-8c47fa41f9dc64441869adb8f390b8ec!}

{!LANG-916e0211b78a9ee8f9e991a7460f4199!}

{!LANG-da81bdcc929a74aa066d878cfee2d3c5!}

{!LANG-87cd76327513759a8e96e5a363b292de!}

{!LANG-7881b635c462aeea57bc33d621577ca5!}

{!LANG-c096872e341c6c6251bfbc5d9511f70b!}

{!LANG-eda1a892d0b7ef74d70bd755e077d2b9!}

, (2.4)

{!LANG-aca2c8c50e228617b0653e6949415ece!}

{!LANG-dc99e1adb6011e03a3c4eb3020715b8f!}

{!LANG-2e8d744244674c8c883522beb42ef40b!}

{!LANG-d6f8b7ed017a1dbbfe450198d466ead8!}

{!LANG-eab6c77060a608614d8c779f53795a47!}

{!LANG-99dab0436e65dc79eb2c12103bddba5b!}

{!LANG-314891e221f0a049df13a696b648fd7f!}

{!LANG-d82fe80eddefae436058de8353759f42!}

{!LANG-8032a729305c41706678742f589e9739!}

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

, (2.5)

{!LANG-188397004497e1b540e19b607d1d11fb!}

{!LANG-8a3a9791594c79fd0776127f5b679ed8!}

{!LANG-56f8f150aa73a6805471a767b2847aaf!}

{!LANG-2300ee52684009e70e69df659927d806!}

{!LANG-510d66c7bc9205d566dbc184ac0c705d!}

{!LANG-9a526b2c22491e2ff595843052562012!}

, (2.6)

{!LANG-ee7ab2517870b6c8bbe9e0a828f01a6a!}

{!LANG-ea773a52599ebbfa731fbc02a910cec1!}

{!LANG-9644bdd96823aeeeaa49eccfa0686013!}

{!LANG-f51e2e3d47c8ac08e079282d05dc6234!}

{!LANG-3b0079a45f72308da4fa0cb85db60025!}

{!LANG-2039b242563c69816a898bae5d6f2eb3!}		{!LANG-a05e3ae1e3beaea9fa81e534165cb852!}
	{!LANG-db09b147467393856b6d57263f618d7d!} {!LANG-7521f3b1cc249ad2662159ac59a83d5f!}		{!LANG-db09b147467393856b6d57263f618d7d!} {!LANG-7521f3b1cc249ad2662159ac59a83d5f!}

{!LANG-6519b0165043339e10ad536de64e289c!}

{!LANG-d1e9e5a693d7df174bf2058ff63ad92f!}

{!LANG-a4e9b24758d72d4b92d5b44e4a173f35!}

{!LANG-884d313595cfeb9fe70662e54048b201!}

{!LANG-bde4621bdcfdd10366b4bdeb9a08420c!}

{!LANG-4f3b6fb1b4c2d64ca2639973cf951b68!}

{!LANG-143512a70e94d4be96dad6a2e5dab117!}

{!LANG-fe537150e6a7e845691f6f735b98c15a!}

{!LANG-ae2f36d13248bfcbf41ef4e38da8c970!}

{!LANG-6592b92a5472cd7a87334d0b2be71ba4!}

{!LANG-34cb63775b198e34a7cb0e2cec6a96a5!}

{!LANG-89f47a38c36efefb3fb840e08d7315c8!}

{!LANG-d628b2886007b2086b3c1c132e0f66c1!}

{!LANG-a3c445ffb85e32c608cbaea0899b89e8!}

{!LANG-5129d5c8de5150cf0f120591c1853dd4!}

{!LANG-a1c713b0760fa5a8d18197d364a28b5e!}

, (3.3)

{!LANG-72a743165e78903711c53472df60d254!}

{!LANG-3206dfbce525f0a2e716911d20e26aba!}

{!LANG-b220c020ef00b38535a5a798767bdad8!}

{!LANG-983423e555659d8b9c7d3f673def5c0b!}

{!LANG-8a7e71e14a0b574d7c0ce4594b511eda!}

, (3.4)

{!LANG-3abc94ef2eab269ec10602628afe50c0!}

{!LANG-953e1028e31612a8ecc65ef9de6b682d!}

{!LANG-247a634f57800415ab7fe727ad1a1752!}

{!LANG-86e2ccbed2ff79fb5f9761faebe3b4ef!}

{!LANG-e5145718bb4cb751b9739e0b5980d404!}

{!LANG-951c01c03c3c7dae4efc9e1a5c99488d!}

{!LANG-a2628e9e4b13160b18e9461d88f703fd!}

{!LANG-af19c3b1896cf2dd783660f7a73683e9!}

, (3.6)

{!LANG-14036ce15a2b493b7b34b6d37586c391!}

{!LANG-001924dd4b64a7706cbf20645ba7086c!}

{!LANG-6af0b1352ae88daa79523d85a25673ec!}

{!LANG-edc68a7c530e1bf6ac979cb89c2bc03a!}

{!LANG-3d84d8d7959b793452ccc4dc2ae7d2e3!}

{!LANG-bcbef262b0a8f88e299cf58e6120779b!}

{!LANG-c4f2b2a4b20eec0f42523d658d79fd72!} {!LANG-a5696a66ed0017272b42036a00729506!}

{!LANG-ebf77d280aa772a9f525a8ef9a0f2a6c!}

{!LANG-9098d05033ba47098c602b697659a0df!}

{!LANG-4cb0eb24e17b1069cdd5e472cda3c82a!}

{!LANG-0b63282c207a7068f86f677713890811!}

{!LANG-f1580c3934301dfc46578eec4b02fa09!}

, (3.7)

{!LANG-b4105a8365f96fbf4ef90b1000a2102e!}

{!LANG-dfaa8b5f5e3ecc7168743096b6898038!}

{!LANG-a49cb03a839e7348d3c4d8500f4536bc!}

{!LANG-f4a72b9881d719c6922d1cd44a64ec49!} {!LANG-b90f7493a5adfa32c50372585c9c0a23!}{!LANG-afd904ab422a47573c911e4f5e153d6b!}

{!LANG-65b0d24ed4cf54b2ec439a09d69d0950!}

, (3.8)

{!LANG-b4105a8365f96fbf4ef90b1000a2102e!}

{!LANG-ebb34651f0b9e0ed78c13cbb1ad2659e!}

{!LANG-fc859e9c76f8266ca97681827a9bc8a1!}

{!LANG-43b13faee6302ab51930f0ebadbc5174!}

{!LANG-dc55d0ce0862ba1abb58cb0b7e6a0a92!}

, (3.9)

{!LANG-36ab73f97108d97deb15005a20b48051!}

{!LANG-096120b8318f05ba42b011248c3da793!}

{!LANG-ee430290cd06eb5a21134d534074ef7f!}

{!LANG-61e634350346261d0be3283b7116ec5b!}

{!LANG-57180a37f43fce9ee1141dd9a607c189!}

{!LANG-13458f416b21ebb2a729fffad294a0f3!}

, (3.10)

{!LANG-69c2892b0e9404e6fba61a39316121ec!}

{!LANG-25e6f343ee95f7e8fbddab6c86d51511!}

{!LANG-e2d5963650a874c1fa819fe72b648f4a!}

{!LANG-10967b293ee38c624f880ed2bc3f626b!}

{!LANG-777ecdc629cf07fad4406ab02cc0e37e!}

{!LANG-0bef082bb6b1b8a5f757d1fc4dd6a85b!}

{!LANG-da79fba1dc525d047fe5f95872d9676b!}

{!LANG-29416edc1c6b030cda61a693163d287e!}

{!LANG-727a8824812a6ac965a84b709efb402a!}

, (3.12)

{!LANG-b9446365418c8ee365fdb08be6330b20!}

{!LANG-32e7b540cb0cd90e8ad5a77a3f11230d!}

{!LANG-60fb5e43a65f4a0b6863b4de2352be9c!}

, (3.14)

{!LANG-808dfc3f24198284d7296ff5f33d5ce6!}

{!LANG-b9446365418c8ee365fdb08be6330b20!}

{!LANG-e8b3bace94c585b3b77f69c45917dcce!}

{!LANG-91ed8b0f290db97a301a6bbf33f525e0!}

{!LANG-e1ad7e90cb60e8d189a31ee371419f12!}

{!LANG-b9446365418c8ee365fdb08be6330b20!}

{!LANG-a65a3d8a41354cf893f3f77a6569de28!}

{!LANG-3968a58933d210ea9ae76306e696afa8!}

{!LANG-50d720ae43c4c027fe4783042da030c6!}

{!LANG-7a1caca722bad608c817ade3f19f80ea!}

{!LANG-22d55dc8102df1cc25b1bdf68340379c!}

{!LANG-2204d4cebd9a6501ad80c153ecf793ae!}

{!LANG-55360713e0791c4fd241e902cd052fbf!}

{!LANG-e7681977d8359465c93f6bbf2fb679b5!}

{!LANG-e821dc5656e390594a441c3162c42a74!}

{!LANG-9fcc4106e2800d15ad4d715ea5edb131!}

{!LANG-2c852ef35e45c652b52968dea692ee36!}

{!LANG-6dbd566778cde39b4abcd771c3de06b0!}

{!LANG-7fc1dd0ba2cb6043e32fa24bb4aa996d!}

{!LANG-f6affd46f010f9e0eb3c3514c8f0b7f2!}

, (3.17)

{!LANG-57294100de6998aa89ed9a52675ca534!}

{!LANG-0bef082bb6b1b8a5f757d1fc4dd6a85b!}

{!LANG-6410c877a0d537820bfcc0031da96525!}

{!LANG-f0ced4750d5258a520f0406cc949ba8c!}

{!LANG-99a5ddf3f4a64507a3533053aea75191!}

, (3.18)

{!LANG-a505e4859c3b6736b5f96e616b8fea13!}

{!LANG-0bef082bb6b1b8a5f757d1fc4dd6a85b!}

{!LANG-575c4fb1aa7ca4cb9cf060f478f80cac!}

{!LANG-b96077682ceefb1aa7964e58abbb7db9!}

{!LANG-c2f21f6e7c303d07de49e7bd6244010b!}

{!LANG-17953c18acfedbfb29c4f4cbdb60d117!}

{!LANG-ae962a633c9a38a690d107ad38d8e2ff!}

{!LANG-9d059a9cc2e7baab230e4b41fbbb3afe!}

{!LANG-2c22311eecf66965684eee0bd7bf0abb!}

{!LANG-f89c805f0564d187bedd4436b95ecde0!}

{!LANG-d235143346ebe783d30799498758e14c!}

, (3.20)

{!LANG-943fbadfe183191ebc038cf5d7ac2189!}

{!LANG-5a7e8818699a4e785efcc28729d62b9c!}

{!LANG-a24a7416edba53973dc0e444d6ecbcff!}

{!LANG-a7b87a71fa45c369adf7b92dba21aa56!}

{!LANG-c4aa222af310c56b24f960a0ad7563a6!}

, (3.21)

{!LANG-944bfd860de4c233857bd32cf76b11e1!}

{!LANG-83ec83833dc064874e7a51d313cb7312!}

{!LANG-d075eb1aed7f2c5c4efbc008af44157b!}

{!LANG-e78864ddd8018f3cf4e3c36c52cef36c!}

{!LANG-a9180d5395e4f2698496d10e17f45b43!}

{!LANG-a492f4f9b30b15086345f07371217819!}

{!LANG-883f67d4e9c120ec64bacc6f2858a9d2!}

{!LANG-c427e834eb9c49668ffbbbb249ab0f4b!}	{!LANG-5c4db0bed79c4ddd4f16bead5a2ede31!}	{!LANG-30a3c7be3515ff6839df7dc3982a5543!}
{!LANG-c427e834eb9c49668ffbbbb249ab0f4b!}
{!LANG-cf924022193ed9fa3018dd77f8e690ac!} {!LANG-a7aa86b8154da2c71fb6f9fe78eb3d90!}{!LANG-b6c762f1c39c5efdb4fa961595aec15e!}
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Students must take technical conditions for the manufacture of welded structures at factories in the OGS or in the assembly and welding bureau, where they undergo technological practice.

{!LANG-68ec1d95a257c24e3188afe73ecb288c!}

{!LANG-f093db39ed9f19f63dbd01f586db9b7a!}

In manual arc welding, electrodes of at least E42A type 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.

The welding wire must be free from rust, oil and other contamination.

Requirements for workpieces for welding provide that the parts to be welded from sheet, shaped, section and other rolled products must be straightened before being assembled for welding.

After rolling or bending, the parts must be free of cracks and burrs, tears, waviness and other defects.

{!LANG-7b4d945968860efd7af11db98f39a702!}

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

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

Parts intended for resistance welding, at the joints, must be free of scale, oil, rust and other contaminants on both sides.

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

The specified requirements are provided by technological equipment and corresponding tolerances for assembled parts.

During assembly, a force fit is not allowed, which causes additional stresses in the metal.

{!LANG-778e7443822d52ffab827aaedf9aafae!}

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

Tacking of welded structure elements during assembly should be performed using the same filler materials and requirements as when making welds.

{!LANG-0def3294676c4e55ccda7d731a5669c5!}

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

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

The surfaces of the parts at the locations of the welds should be checked before welding. The edges to be welded must be dry. Traces of corrosion, dirt, oil and other contamination are not allowed.

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

The deviation of the dimensions of the cross-section of the welded seams specified in the drawings when welding in carbon dioxide must be in accordance with GOST 14771-76.

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

{!LANG-02bf204090a54d5a3ab9841199ee62f3!}

The increase in the diameter of the contact surface of the electrode during the welding process should not exceed 10% of the size established by the technological 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 resistance spot welding of parts of different thickness, 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 correspond to the drawing of the welded structure in accordance with GOST 14776-79.

{!LANG-97a9a89a15aac63a048bbbb46667c324!}

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

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

Convex and concave fillet seams are allowed, but in all cases the leg of the seam should be considered the leg of an isosceles triangle inscribed in the seam section.

Inspection can be carried out without using a magnifying glass or using it with a magnification 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 graduation of 0.1 or special templates.

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

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

{!LANG-1b75b6e50e1a24775b05d59b0041a55c!}