Diagnostics of the technical condition of technological equipment. Equipment diagnostics. Methods and tools for diagnostic monitoring of pumping units
GOST 20911-89 provides for the use of two terms: "technical diagnostics" and "technical condition control". The term "technical diagnostics" is used when the solved problems of technical diagnostics listed in 1.1 are equivalent or the main task is to find a place and determine the causes of failure. The term "technical condition control" is used when the main task of technical diagnostics is to determine the type of technical condition.
There are the following types of technical condition, characterized by the value of the parameters of the object at a given moment in time:
Serviceable - the object meets all the requirements of the regulatory and technical and (or) design documentation;
Defective - the object does not meet at least one of the requirements of the normative-technical and (or) design documentation;
Efficient - the values of all parameters characterizing the facility's ability to perform the specified functions comply with the requirements of the normative-technical and (or) design documentation;
Inoperative - the value of at least one parameter characterizing the facility's ability to perform the specified functions does not meet the requirements of the normative-technical and (or) design documentation;
Limiting - further operation of the facility is technically impossible or impractical due to non-compliance with the requirements
safety or irreparable decrease in work efficiency.
The concept of "healthy" is broader than the concept of "healthy". If the object is healthy, it is sure to be functional, but a functional object may be faulty, since some malfunctions may be insignificant, not disrupting the normal functioning of the object.
For complex objects, in particular for main pipelines, a deeper classification of the operable state is allowed with the allocation of a partially operable (partially inoperable) state in which the object is able to partially perform the specified functions. An example of a partially operable state is the state of the linear part of the main pipelines, in which the section is able to perform the required functions for pumping the process medium with reduced performance, in particular, with reduced productivity with a decrease in the allowable pressure (RD 51-4.2-003-97).
Technical diagnostics system(technical condition control) is the set of means, object and performers necessary for diagnostics (control) according to the rules established in the technical documentation. The objects of technical diagnostics are technological equipment or specific production processes.
Control tool -technical device, substance or material for control. If the control means provides the ability to measure the controlled value, then the control is called measuring. Controls are built-in, which are an integral part of the object, and external, made structurally separate from the object. A distinction is also made between hardware and software controls. Hardware includes various devices: devices, consoles, stands, etc. Software means are computer applications.
Performers - these are specialists of the control service or technical diagnostics, trained and certified in the prescribed manner and having the right to carry out control and issue conclusions based on its results.
Control methodology - a set of rules for the application of certain principles and controls. The technique contains the procedure for measuring parameters, processing, analyzing and interpreting the results.
For each object, you can specify a variety of parameters that characterize its technical condition (PTS). They are chosen depending on the method of diagnosis (control) used. Changes in the PFS values during operation are associated either with external influences on the object, or with damaging (degradation) processes (processes leading to degradation failures due to metal aging, corrosion and erosion, fatigue, etc.).
The parameters of an object used in its diagnostics (control) are called diagnostic (controlled) parameters. A distinction should be made between direct and indirect diagnostic parameters. A direct structural parameter (for example, wear of rubbing elements, clearance in the interface, etc.) directly characterizes the technical condition of the object. An indirect parameter (for example, oil pressure, temperature, CO2 content in exhaust gases, etc.) indirectly characterizes the technical condition. The change in the technical state of the object is judged by the values of the diagnostic parameters, which make it possible to determine the technical state of the object without disassembling it. A set of diagnostic parameters is established in the normative documentation for the technical diagnostics of an object or is determined experimentally.
Quantitative and qualitative characteristics of diagnostic parameters are signs of a particular defect. Each defect can have several features, including some of them that may be common to a group of defects of different nature.
The general theory of pattern recognition, which is a section of technical cybernetics, is considered the theoretical foundation of technical diagnostics. There are two approaches to solving the recognition problem: probabilistic and deterministic. Probabilistic uses statistical relationships between the state of an object and diagnostic parameters and requires the accumulation of statistics on the correspondence of diagnostic parameters to types of technical conditions. In this case, the assessment of the condition is carried out with a certain reliability. The deterministic approach, which is most often used, uses the established patterns of changes in the diagnostic parameters that determine the state of the object.
In addition to the recognition theory, the theory of controllability is also used in technical diagnostics. Controllability is determined by the design of the object, is set during its design and is a property of the object to provide the possibility of a reliable assessment of diagnostic parameters. Insufficient reliability of the technical condition assessment is the fundamental reason for the low reliability of equipment condition recognition and assessment of its residual life.
Thus, as a result of previous studies, relationships are established between the characteristics of diagnostic parameters and the state of the object, and diagnostic algorithms (recognition algorithms) are developed, which are a sequence certain actions required for the diagnosis. Diagnostic algorithms also include a system of diagnostic parameters, their reference levels and the rules for making a decision about the belonging of an object to a particular type of technical state.
Determination of the type of technical condition of the equipment can be carried out both in the assembled state and after its complete disassembly. During normal operation, CIP methods are used as the most economical. Methods of technical diagnostics requiring disassembly are usually used during the overhaul of equipment - when detecting its elements. The main problem of CIP technical diagnostics is the assessment of the equipment condition in conditions of limited information.
According to the method of obtaining diagnostic information, technical diagnostics are divided into test and functional. In test diagnostics, information about the technical condition is obtained as a result of the impact on the object of the corresponding test. Test diagnostics are based on the use of different methods non-destructive testing. In this case, monitoring is carried out, as a rule, on non-working equipment. Test diagnostics can be performed both assembled and disassembled. Functional diagnostics are carried out only on operating equipment in an assembled state.
Functional diagnostics, in turn, are subdivided into vibration and parametric diagnostics. When using functional parametric diagnostics, the technical condition is assessed by the value of the functional parameters of the equipment during its operation, while the supply of targeted test influences is not required. The deviation of these parameters from their nominal values (temperature, pressure, power, amount of pumped product, efficiency, etc.) indicates a change in the technical state of the elements of the object that form this parameter. Functional parameters are usually monitored continuously by operating personnel using standard instrumentation and measuring complexes. technological equipment... In this regard, functional parametric diagnostics is often called operational. The methods of functional parametric diagnostics are usually described in the instructions and manuals for the operation of the corresponding type of equipment and are not specifically discussed in this manual.
There are two types of vibration diagnostics: test and functional (see 2.1). The essence of functional vibration diagnostics is to use the vibration parameters of the equipment when operating under operating conditions to assess its technical condition without disassembly. A feature of functional vibration diagnostics is the use of not static parameters such as temperature or pressure as diagnostic parameters, but dynamic ones - vibration displacement, vibration velocity and vibration acceleration.
In addition to the types of diagnostics noted above, destructive testing methods are used to assess the condition of the equipment, providing for partial destruction of the object (for example, when cutting out samples to establish the properties of materials by means of their mechanical tests), as well as instrumental measuring control elements of equipment when disassembling it during inspection or repair. The classification of types of technical diagnostics is shown in Fig. 1.3.
Diagnostic systems differ in the level of information received about the object. Depending on the problem to be solved, the following types of diagnostic systems are distinguished: for sorting objects into serviceable and faulty ones, or for attesting objects by class; search and measurement of defects and damages; monitoring the state of the object and predicting its residual life. The last of the listed systems is the most complex and is used for critical and expensive hazardous production facilities and technological equipment. Such systems, which provide for continuous monitoring using a set of methods for monitoring the technical condition, allow for the prompt correction of predictive estimates of the defining parameters and the refinement of the residual resource. The main methods for monitoring the development of defectiveness in integrated monitoring systems are currently used: for capacitive equipment - acoustic emission control, for machine equipment - control of vibration parameters.
Modern technological equipment is a complex technical system. Ensuring the required reliability of such systems, assessed by the probability of no-failure operation P (1)(see Table 1.1) is more problematic than simple ones. Reliability any technical system is determined by the reliability of its constituent elements. In most cases, for complex systems, control of one or several elements is ineffective, since the state of the rest remains unknown.
The constituent elements of complex technical systems can be interconnected in sequential, parallel or combined ways. With a series connection of elements with a probability of failure-free operation R 1 R 2,..., Pn the probability of failure-free operation of the system is determined from the expression
,
Where P i - the probability of failure-free operation of the i-th element.
Parallel connection
With the combined method, the probability of failure-free operation of the elements with parallel connection is first determined, and then with serial connection.
Way parallel connection duplicate elements is called reservation. Redundancy can dramatically increase the reliability of complex technical systems. For example, if the crude oil pumping system has two independent parallel pumps with the probability of failure-free operation P 1 = P 2 = 0.95, then the probability of failure-free operation of the entire system
P (t)= 1 - (1 – R 1) (1- P 2) = 1 - (1 - 0.95) (1 - 0.95) = 0.998.
The overall reliability of the system is determined by the reliability of its components. The greater the number of components that make up the system, the higher should be the reliability of each of them. For example, if a technical system consists of 100 series-connected elements with an equally high probability of failure-free operation of 0.99, then its overall reliability will be equal to 0.99 100, which will be about 0.37, i.e., the probability of failure-free operation of the system for a given time t is only 37%. In this regard, when diagnosing complex systems, primarily including a large number of components without redundancy, in order to obtain a reliable assessment of their reliability, it is necessary to carry out a complete control of all components.
The state of a technical system can be described by many parameters. When diagnosing complex systems, the performance of which is characterized by a large number of parameters, a number of additional problems arise, namely:
It is necessary to establish the nomenclature of the main diagnostic parameters that characterize the system performance, and set technical means their control;
Based on the combination of these parameters, it is necessary to develop an algorithm for assessing the technical state of the system and the corresponding software products for computers.
When carrying out diagnostics, continuous and random control is used. Extremely important factor is that the use of modern non-destructive methods allows you to go to continuous testing. For complex technological equipment, consisting of a large number of dependent elements, the introduction of continuous non-destructive testing is a necessary condition for a reliable assessment of its technical condition.
Diagnostics requires a certain cost, which grows as the requirements for reliability and safety increase. For comparison: in nuclear industry In the USA, the cost of flaw detection is up to 25% of all operating costs, in Russia - about 4%. According to VNIKTI petrochemical equipment, the cost of diagnostics of petrochemical equipment in the United States is about 6% of operating costs, in Russia - less than 1%. At the same time, this expense item is justified, since the use of technical diagnostics systems allows each piece of technological equipment to be operated to the limit state and, due to this, to obtain a significant economic effect.
– important process, which should be regularly carried out in industrial plants.
High-quality and timely execution of operations, performed in accordance with regulatory documents, can prevent potential breakdowns and malfunctions of specialized equipment.
Diagnostics of technological equipment performs many functions and tasks.
One of the priorities for this process is to ensure the safe and high-quality operation of machines, apparatus and machines on domestic enterprises... The diagnostics also ensure the reliability of the facility.
A well-conducted survey guarantees a reduction in the consumption of material resources of the enterprise for maintenance, as well as during scheduled preventive maintenance (PPR).
Diagnostics of machines, tools, machines makes it possible to assess the real state of the equipment at the moment.
Diagnostics also reveals the exact location of a potential or existing problem. By evaluating the performance indicators of the equipment, it is possible to establish the power and efficiency of its labor operation.
With the help of a general assessment of the technical condition of equipment, a forecast for its further use is made and exact time its maximum exploitation in production.
There are two types of diagnostic parameters: direct and indirect. In this case, the first characterize directly the current state of the object, and the second speak about the functional dependence of the direct parameters.
Technological equipment diagnostics methods
Diagnostics of technological equipment is carried out using various methods, in particular:
- organoleptic;
- vibrating;
- acoustic;
- thermal;
- magnetic powder;
- vortex;
- ultrasonic;
All these methods are widely used in assessing the condition of objects at industrial enterprises.
It is important to remember that the diagnostics of technological equipment has its drawbacks. One of them is the skipping of a problem while examining. This may later cause damage to the equipment or lead to the receipt of work-related injuries workers.
Another big drawback of technological diagnostics is the emergence of a high probability that the alarm was false and there are no potential threats to the operation of the equipment.
Inspection of units requires, first of all, time. At the same time, all equipment remains inoperative, which leads to downtime.
The equipment of the material and technical base is important for every enterprise. Especially carefully you need to monitor the serviceability of the equipment, the timely replacement of consumables. This contributes to the efficient functioning of the enterprise.
Planned preventive work at all organizations is carried out through regular checks in accordance with all the requirements of regulatory documents.
Modern diagnostic methods for technological equipment at the exhibition
Will present best samples metalworking equipment, as well innovative technologies in the field of metalworking. Including will be discussed modern methods diagnostics of technological equipment.
Traditionally, the exhibition will take place in the international complex "Expocentre".
Leading domestic and foreign experts will present the latest developments, talk about the problems and prospects for the development of the industry.
System of maintenance and repair of general industrial equipment: Handbook of Yashchur Alexander Ignatievich
3.3. Equipment technical diagnostics
3.3.1. Technical diagnostics (TD) is an element of the PPR System that allows you to study and establish signs of malfunction (operability) of equipment, establish methods and means by which a conclusion is given (a diagnosis is made) about the presence (absence) of malfunctions (defects). Acting on the basis of studying the dynamics of changes in the indicators of the technical condition of the equipment, the TD solves the issues of forecasting (foreseeing) the residual resource and the trouble-free operation of the equipment within a certain period of time.
3.3.2. Technical diagnostics is based on the assumption that any equipment or its component part can be in two states - serviceable and faulty. Serviceable equipment is always operational, it meets all the requirements of the technical specifications established by the manufacturer. Defective (defective) equipment can be both operable and inoperative, that is, in a state of failure.
3.3.3. Equipment may fail due to a change external environment and due to physical wear and tear of parts located both outside and inside the equipment. Failures are the result of wear or misalignment of components.
3.3.4. Technical diagnostics is mainly aimed at finding and analyzing the internal causes of failure. External causes are determined visually, using a measuring tool, simple devices.
Methods, means and a rational sequence of searching for internal causes of failure depend on the complexity of the equipment design, on the technical indicators that determine its condition. The peculiarity of TD is that it measures and determines the technical condition of the equipment and its components during operation, directs its efforts to search for defects.
3.3.5. By the size of the defects of components (units, assemblies and parts), it is possible to determine the operability of the equipment. Knowing the technical condition of individual parts of the equipment at the time of diagnosis and the magnitude of the defect in which its performance is impaired, it is possible to predict the uptime of the equipment until the next scheduled repair, provided for by the frequency standards of the PPR System, as well as the need to correct them.
3.3.6. The periodicity standards laid down in the basis of the PPR are experimentally averaged values, established so that the repair periods are multiple and tied to scheduling main production (year, quarter, month).
3.3.7. Any averaged values have their own significant drawback: even with a number of clarifying coefficients, they do not give a complete objective assessment of the technical condition of the equipment and the need for scheduled maintenance. Almost always there are two superfluous options: the residual resource of the equipment is far from being exhausted, the residual resource does not ensure trouble-free operation until the next scheduled repair. Both options fail to meet the requirement Federal law No. 57-FZ on setting deadlines useful use fixed assets by objectively assessing the need for repair or decommissioning.
3.3.8. An objective method for assessing the need for equipment for repair is constant or periodic monitoring of the technical condition of the facility with repairs only in the case when the wear of parts and assemblies has reached the limit value, which does not guarantee safe, trouble-free and economical operation of the equipment. Such control can be achieved by means of TD, and the method itself becomes an integral part of the SPR (control) system.
3.3.9. Another task of the TD is to predict the residual life of the equipment and establish the period of its trouble-free operation without repair (especially capital), that is, adjusting the structure of the repair cycle.
3.3.10. Technical diagnostics successfully solves these problems for any repair strategy, especially a strategy for the technical condition of equipment. In accordance with this strategy, work on maintaining and restoring the operability of equipment and its components should be carried out on the basis of equipment TD.
3.3.11. Technical diagnostics is an objective method for assessing the technical condition of equipment in order to determine the presence or absence of defects and the timing of repairs, including predicting the technical condition of equipment and adjusting the standards for the frequency of repairs (especially overhaul).
3.3.12. The basic principle of diagnostics is to compare the regulated value of the operating parameter or the parameter of the technical condition of the equipment with the actual value using diagnostic tools. Here and below, according to GOST 19919-74, a parameter is understood as a characteristic of the equipment that reflects the physical value of its functioning or technical condition.
3.3.13. The objectives of the TD are:
control of the functioning parameters, i.e., the course of the technological process, in order to optimize it;
monitoring the parameters of the technical condition of the equipment changing during operation, comparing their actual values with limit values and determining the need for maintenance and repair;
forecasting the resource (service life) of equipment, units and assemblies in order to replace them or take them out for repair.
3.3.14. Forecasting the frequency of the current and, especially, overhaul equipment is possible only with the simultaneous TD of all or most of its components.
3.3.15. Experience shows that the most effective use of the advantages of TD is achieved when a special task "Diagnostics of equipment", provided with computer technology, is functioning at the enterprise.
Despite the wide variety of devices used for diagnosing equipment, sensor wiring diagrams, their design performance, etc., as domestic and world experience shows, approaches to the introduction of TD into practice remain common. Appendix 8 briefly discusses the methodology and shows one of the general ways of organizing TD at the enterprise, and in table. 3.1 shows a list of diagnostic devices available in special mobile repair shops.
Table 3.1
List of diagnostic devices in mobile repair shops
The Academy of Sciences (AS) of the USSR and the Soviet scientific and technical elite of the Academy of Sciences of the USSR traditionally consisted of scientists whose professional careers often implied high positions in either industrial or military organizations. Due to this feature, academicians and
From the book Creativity as an Exact Science [Theory of Inventive Problem Solving] the author Altshuller Genrikh Saulovich From the book Rules technical exploitation thermal power plants in questions and answers. A guide to study and prepare for knowledge testing the author2.8. Technical documentation for thermal power plants Question 83. What documents are stored and used in operation during the operation of thermal power plants? The following documents are stored and used in the work: general plan with applied buildings,
From the book Electrical Installation Rules in Questions and Answers [A guide for studying and preparing for knowledge testing] the author Krasnik Valentin ViktorovichSanitary part Question. What ventilation system should be installed in the storage battery rooms, in which the batteries are charged, at a voltage of more than 2.4 V per cell? Must be equipped with a stationary forced
From the book Electricity management of enterprises the author Krasnik Valentin ViktorovichCHAPTER 4 REGULATORY AND TECHNICAL DOCUMENTATION IN ELECTRICAL INSTALLATIONS 4.1. Technical documentation The presence of a complete and high-quality technical documentation in electrical installations is an important prerequisite for organizing and maintaining an appropriate level of electrical equipment. Her underestimation is fraught
From the book Determination and elimination of malfunctions on your own in a car the author Zolotnitsky Vladimir4.1. Technical documentation The presence of a complete and high-quality technical documentation in electrical installations is an important prerequisite for organizing and maintaining an appropriate level of electrical equipment. Underestimating it is fraught with undesirable consequences.
From the book Japanese Car Repair the author Kornienko SergeyDiagnostics of malfunctions of the steering and their elimination. Increased gear but the steering wheel of road jolts when the car is moving. Vibration and knocks felt on the steering wheel
From the book System of maintenance and repair of general industrial equipment: Handbook the author FMD Alexander IgnatievichGeneral diagnostics
From the book We Maintain and Repair Volga GAZ-3110 the author Zolotnitsky Vladimir Alekseevich3.3. Technical diagnostics of equipment 3.3.1. Technical diagnostics (TD) is an element of the PPR System that allows you to study and establish signs of malfunction (operability) of equipment, establish methods and means by which a conclusion is given
From the book Tips of an auto mechanic: maintenance, diagnostics, repair the author Savosin SergeyTechnical specifications car GAZ-3110 sedan General data Number of seats (including the driver's seat) - 5. Weight of equipped car, kg - 1400. Overall dimensions, mm: - length - 4880.- width - 1800.- height without load - 1455. Wheelbase (distance between axes), mm
From the BIOS book. Express course the author Traskovsky Anton ViktorovichSergey Savosin Auto mechanic advice: maintenance, diagnostics,
From the book Materials Science. Crib the author Buslaeva Elena Mikhailovna2.3. Diagnostics and maintenance Diagnostics is a Greek word for recognition, identification of symptoms. Before proceeding with the repair of the car, it is necessary to carry out a thorough diagnostics of it.
From the author's book3.2. Diagnostics and maintenance The electrical system of a car consists of a power source and various consumers that provide ignition of the working mixture, lighting, alarm and vehicle control systems. As stated earlier,
From the author's book4.2. Diagnostics and maintenance 4.2.1. Diagnostics and maintenance of the clutch maintenance The clutches are periodically checked and the drive adjusted. Service begins by checking the pedal function. The pedal must move along the entire stroke
From the author's bookPart III Diagnosis and Troubleshooting
From the author's book51. Inorganic glasses. Technical ceramics Inorganic glass - chemically complex amorphous isotropic materials with the properties of a brittle solid. Glass consists of: 1. Glass formers - base: a) Si02 - silicate glass, if Si02> 99%, then this
Significant expenses for the maintenance of equipment are primarily due to the low quality of its maintenance and premature repairs. To reduce labor costs and funds for maintenance and repair, it is necessary to increase productivity and improve the quality of these works by increasing the reliability and operational adaptability (maintainability) of manufactured units, development and better use of the production and technical base of enterprises, mechanization and automation of technological processes, implementation diagnostic tools and elements scientific organization labor.
Under reliability understand the property of the machine components to perform the specified functions, keeping in time the values of the established operational within the specified limits, corresponding to the specified modes and conditions of use, maintenance, repairs, storage and transportation.
Reliability during operation depends on a number of factors: the nature and volume of work performed by the machine; natural and climatic conditions; the adopted system of technical maintenance and repair of equipment; quality and availability of normative and technical documentation and means of maintenance, storage and transportation of machines; qualifications of service personnel.
Reliability is a complex property, which includes, depending on the purpose of the object or the conditions of its operation, a number of simple properties:
1. Reliability - the property of an object to continuously maintain operability for some operating time or for some time.
2. Durability - the property of the object to remain operational until the onset of the limiting state with the established system of maintenance and repairs.
3. Maintainability - property of an object, which consists in its adaptability to preventing and detecting the causes of failures, maintaining and restoring operability through repairs and maintenance.
4. Persistence - the property of the object to continuously maintain the required performance indicators during (and after) the period of storage and transportation.
Depending on the object, reliability can be determined by all of the listed properties or some of them. For example, the reliability of a gear wheel and bearings is determined by their durability, and the reliability of a machine tool - by durability, reliability and maintainability.
The car is a complex system consisting of thousands of parts with various manufacturing and operational tolerances. The work is carried out in different conditions, therefore, the service life of the same type of objects is different - depending on the operating conditions, operating modes and the quality of the elements. Therefore, each unit must be sent for repairs in accordance with its actual condition.
An individual examination (control, diagnostics, forecasting) establishes the True technical condition of each unit. Here the influence of the whole variety of working conditions, operator qualifications and other factors, on which the technical condition of the object depends, can be taken into account.
The lack of special monitoring and diagnostic equipment makes it difficult to detect many malfunctions. Old (mostly subjective) methods can only identify significant and obvious failures and deviations. The cost of checking basic systems with such methods is about 70-75% higher than when using modern diagnostic methods.
Technical diagnostics method - a set of technological and organizational rules for performing technical diagnostics operations.
Diagnostics (from the Greek diagnostikós - capable of recognizing) is a branch of knowledge that studies the technical condition of objects to be diagnosed (machines, mechanisms, equipment, structures and other technical objects) and the manifestation of technical conditions, develops methods for their determination, with the help of which a conclusion is given (a diagnosis is made) , as well as the principles of construction and organization of the use of diagnostic systems. When the objects of diagnostics are objects of a technical nature, they speak of technical diagnostics.
Diagnostics is a set of methods and means for determining the main indicators of the technical condition of individual mechanisms and the machine as a whole without disassembling them or with partial disassembly.
The result of the diagnosis is diagnosis - conclusion on the technical condition of the object, indicating, if necessary, the place, type and cause of the defect.
Diagnostic reliability- the likelihood that the diagnosis determines the technical state in which the object of diagnosis is actually located.
Technical condition- a set of object properties subject to change in the production or operation process, characterized at a certain point in time by the signs and parameters of the state established by the technical documentation for this object.
Status parameter- a physical quantity characterizing the operability or serviceability of the object being diagnosed and changing during operation.
Diagnostic operation - part of the diagnostic process, the implementation of which allows you to determine one or more diagnostic parameters of the object.
Diagnostic technology - a set of methods, parameters and diagnostic operations performed systematically and sequentially in accordance with the technological documentation to obtain the final diagnosis.
In fig. 1 shows the structure of technical diagnostics. It is characterized by two interpenetrating and interconnected directions: the theory of recognition and the theory of controllability. Recognition theory contains sections related to the construction of recognition algorithms, decision rules and diagnostic models. The theory of controllability includes the development of means and methods for obtaining diagnostic information, automated control and troubleshooting. Technical diagnostics should be considered as a section of the general theory of reliability.
Diagnosis includes three main stages:
· obtaining information about the technical condition of the diagnostic object;
· processing and analysis of the information received;
· diagnosis and decision making.
The first stage consists in determining the parameters of the state of the object, establishing qualitative indicators of the state and obtaining data on the operating time; the second - in processing and comparing the obtained values of the state parameters with the nominal, permissible and limiting values, as well as using the obtained data to predict the residual life; the third - in the analysis of the results of forecasting and the establishment of the scope and timing of maintenance and repair of machine components.
Diagnostic object- the product and its components to be diagnosed.
The following objects are considered in technical diagnostics.
Element- the simplest component part of the product for this consideration, in reliability problems it can consist of many parts.
Product- a unit of products for a specific purpose, considered during the periods of design, production, testing and operation.
System- a set of jointly acting elements, designed to independently perform the assigned functions.
The concepts of an element, product and system are transformed depending on the task at hand. For example, when establishing its own reliability, the machine is considered as a system consisting of separate elements - mechanisms, parts, etc., and when studying the reliability of a technological line - as an element.
Object structure - a conditional diagram of its structure, formed by the sequential division of the object into structural elements (component parts, assembly units, etc.).
When diagnosing, distinguish work impacts, arriving at the facility during its operation, and test influences, which are supplied to the facility only for diagnostic purposes. Diagnostics, in which only working influences are applied to the object, is called functional, and diagnostics, in which test influences are applied to the object, - test technical diagnostics.
The set of tools, performers and objects of diagnostics, prepared for checking the state parameters or carrying it out according to the rules established by the relevant documentation, is called system of technical diagnostics.
Diagnostics allows: to reduce machine downtime due to technical malfunctions by preventing failures by timely adjustment, replacement or repair of individual mechanisms and assemblies; eliminate unnecessary disassembly of individual mechanisms and assemblies and reduce the rate of wear of parts; correctly establish the type and volume of repairs and reduce the labor intensity of current repairs by reducing disassembly and assembly and renovation works; make fuller use of the resources of individual units and the machine as a whole, and, consequently, reduce the total number of repairs and the consumption of spare parts.
The experience of implementing diagnostics shows that the overhaul life increases by 1.5 ... 2 times, the number of failures and malfunctions is reduced by 2 ... 2.5 times, and the cost of repair and maintenance is reduced by 25 ... 30%.
In addition, the system of technical services for a fixed resource (average system) does not provide high reliability and minimum costs... This system is gradually dying out, a new and more economical method of maintenance and repair based on the actual technical condition (diagnostic system) is being introduced more and more. This makes it possible to make fuller use of the overhaul life of machines, eliminate unreasonable disassembly of mechanisms, reduce downtime due to technical malfunctions, and reduce the labor intensity of maintenance and repair. Condition-Based Operation can bring benefits equivalent to 30% of the total fleet.
In some cases, it is advisable to use a combined (mixed) diagnosis - representing a set of regulated technical diagnostics and diagnostics based on technical condition.
For diagnostic and combined systems, new research methods, a different mathematical apparatus are required. The theory of reliability should be the basis. It is necessary to study more deeply and take into account changes in the physical laws of failures, wear and aging of parts in mechanical systems. An important role in improving the management of the reliability of rolling stock belongs to the development and implementation of methods for predicting the technical condition of vehicle units.
Goals and objectives of technical diagnostics. The link between diagnostics and reliability
The purpose of technical diagnostics is to increase the reliability and service life of technical systems. Measures to maintain the reliability of machines are aimed at reducing the rate of change of state parameters (mainly the rate of wear) of their components and preventing failures. As you know, the most important indicator reliability is the absence of failures during the operation (operation) of the technical system.
Technical diagnostics, thanks to early detection of defects and malfunctions, allows to eliminate failures in the process of maintenance, which increases the reliability and efficiency of operation.
7. Diagnostics of the technical condition of the equipment
7.1. Basic principles of technical diagnostics
Diagnostics- a branch of science that studies and establishes the signs of the state of the system, as well as the methods, principles and means by which a conclusion is made about the nature and essence of system defects without disassembling it and the system resource is predicted.
Technical diagnostics machines represents a system of methods and means used to determine the technical condition of a machine without disassembling it. With the help of technical diagnostics, it is possible to determine the state of individual parts and assembly units of machines, to search for defects that caused a stop or abnormal operation of the machine.
Based on the data obtained during diagnostics on the nature of the destruction of parts and assembly units of the machine, depending on the time of its operation, technical diagnostics makes it possible to predict the technical condition of the machine for the subsequent period of operation after diagnosis.
The set of diagnostic tools, an object and performers acting according to established algorithms is called diagnostic system.
Algorithm is a set of prescriptions that determine the sequence of actions during diagnosis, i.e. the algorithm establishes the procedure for carrying out checks of the state of the object's elements and the rules for analyzing their results. Moreover, the unconditional diagnostic algorithm establishes a predetermined sequence of checks, and the conditional one - depending on the results of previous checks.
Technical diagnostics - it is the process of determining the technical condition of an object with a certain accuracy. The result of diagnostics is a conclusion on the technical condition of the object, indicating, if necessary, the place, type and cause of the defect.
Diagnostics is one of the elements of the maintenance system. Its main goal is to achieve maximum efficiency in the operation of machines and, in particular, to minimize the cost of their maintenance. To do this, they give a timely and qualified assessment of the technical condition of the machine and develop rational recommendations for the further use and repair of assembly units (maintenance, repair, further operation without maintenance, replacement of assembly units, materials, etc.).
Diagnosis is carried out both during maintenance and during repair.
During maintenance, the diagnostic tasks are to establish the need for overhaul or current repairs of the machine or its assembly units; the quality of functioning of mechanisms and systems of machines; a list of works that must be performed during the next maintenance.
When repairing machines, diagnostic tasks are reduced to identifying assembly units to be restored, as well as assessing the quality of repair work. The types of technical diagnostics are classified by purpose, frequency, location, level of specialization (Table 7.1). Depending on the car park, diagnostics are carried out by the Operations Enterprise or at specialized technical service enterprises.
Diagnostics, as a rule, are combined with maintenance work. In addition, in the event of machine failures, in-depth diagnostics are carried out at the request of the operator.
Recently, a network of small enterprises has appeared to provide technical service for machines, including diagnostics, i.e. diagnostics in this case is removed from the scope of maintenance work and becomes an independent service (product), which is provided at the request of the client both during the operation period and when assessing the quality of repairs, the residual cost of work to restore the operability and serviceability of machines, as well as when purchasing and sale of used machines.
Diagnostic work at the operational enterprise is carried out depending on the size and composition of the fleet of cars at a specialized diagnostic site (post) or at the maintenance site (post). The object of technical diagnostics can be a technical device or its element. The simplest object of technical diagnostics will be a kinematic pair or conjugation. However, an aggregate of any complexity can be included in the class of objects under consideration. The diagnosed object can be considered in two aspects: from the point of view of structure and mode of functioning. Each of the aspects has features described by its own system of concepts.
Under the structure of the system a certain interconnection, mutual arrangement of the constituent parts (elements) characterizing the device and structure of the system is understood.
Parameter- a qualitative measure that characterizes the property of a system, element or phenomenon, in particular a process. Parameter value is a quantitative measure of a parameter.
Objective diagnostic methods give an accurate quantitative assessment of the assembly unit, machine. They are based on the use of both special control and diagnostic tools (equipment, instruments, tools, fixtures), and installed directly on machines or included in the driver's tool kit.
Table 7.1
Types of diagnostics and their areas of application
|
Qualifying feature |
Diagnosis type |
Application area |
Main goals |
|
At the place of diagnosis By volume By frequency By specialization level |
Operational Production Partial Planned (regulated) Unplanned (causal) Specialized Combined |
During maintenance, inspections, failures and malfunctions When repairing cars at repair enterprises For incoming and outgoing inspection of machines in repair production During technical inspections With periodic maintenance and inspections In the event of failures and malfunctions When servicing machines at service enterprises and by the Central Bank of Applied Physics When repairing machines When servicing machines by the operational enterprise and by the Central Bank |
Determination of the residual life of assembly units and the need for adjustment work. Establishing the scope and quality of repair work, detecting malfunctions, assessing the readiness of machines for work Determination of the residual life of assembly units. Quality control of repair work Determination of the residual life of assembly units, checking the quality of their functioning, identifying a list of adjustments, preventing failures Determining the list of necessary adjustments, checking the readiness of machines for operation or the quality of their storage, identifying faults with their subsequent elimination Prevention of failures, determination of residual life, establishment of a list of adjustment works, quality control of maintenance and repair of machines Identification of failures and malfunctions with their subsequent elimination Diagnostics provided by TO-3 and after overhaul Determination of the residual life of assembly units, checking the quality of repair Diagnostics followed by maintenance of the machine, checking the need for repairs with the elimination of defects. Identification and elimination of defects in the event of failures |
Objective diagnosis is divided into direct and indirect
Direct diagnosis- this is the process of determining the technical state of an object by its structural parameters (clearances in bearing assemblies, in the valve mechanism, in the upper and lower heads of the connecting rods of the crank mechanism, beating of the shafts, sizes of parts available for direct measurement, etc.).
Assembly units and the machine as a whole are diagnosed by structural parameters using universal measuring instruments: calibers, probes, scale ruler, calipers, micrometers, gear meters, standard gauges, etc. This allows you to obtain accurate results. The disadvantage of this method is that in many cases it requires disassembly of the diagnostic object. The latter significantly increases the complexity of the work and disrupts the running-in of mating surfaces. Therefore, in practice, direct diagnostics, as a rule, are carried out in cases where the structural parameters of the diagnosed object can be measured without disassembling the mating surfaces.
Indirect diagnosis - it is the process of determining the actual state of the object being diagnosed by indirect, or, as they are called, diagnostic parameters.
Changes in the parameters of working processes, structural noise, the content of wear products in the oil, power, fuel consumption, etc. are used as indirect indicators.
The diagnostic process itself is carried out using pressure gauges, vacuum gauges, piezometers, flow meters, pneumatic calibrators, opacimeters and various special devices.
It might be helpful to read:
- Listening in Russian lessons Reasons for the language barrier;
- International relations theory;
- Organization and regulation of labor at the enterprise;
- Kiban Personnel Management Service;
- Online exam tests in social studies Society of exam online tests with solution;
- Tariff plans of Rostelecom in g;
- Help Online Rostelecom Internet does not work;
- Configuring a router to work with beeline, online, akado or netbynet;