home » registration » Tickets for non-destructive testing level 2. Theoretical foundations

Tickets for non-destructive testing level 2. Theoretical foundations

MDK 02.02. Gas welding technology

PM.02. Welding and cutting of parts from various steels, non-ferrous metals and their alloys, cast irons in all spatial positions

by profession 150709.02 Welder (electric welding and gas welding)

Testing in pedagogy performs three main interrelated functions: diagnostic, teaching and educational:

· Diagnostic function is to identify the level of knowledge, skills, abilities of the student. This is the main and most obvious function of testing. In terms of objectivity, breadth and speed of diagnosis, testing surpasses all other forms of pedagogical control.

· Teaching function testing is to motivate the student to intensify the work on mastering educational material. To enhance the learning function of testing can be used additional measures stimulating students, such as: distribution by the teacher indicative list questions for self-preparation, the presence of leading questions and hints in the test itself, a joint analysis of the test results.

· educational function manifests itself in the frequency and inevitability of test control. This disciplines, organizes and directs the activities of students, helps to identify and eliminate gaps in knowledge, forms the desire to develop their abilities.

Download:

Preview:

budgetary educational institution Omsk region

elementary vocational education

"Professional School No. 65".

TEST

Visual control during gas welding

MDK 02.02. Gas welding technology

PM.02. Welding and cutting of parts from various steels, non-ferrous metals and their alloys, cast irons in all spatial positions

By profession 150709.02 Welder (electric welding and gas welding)

Compiled by: Baranov Vladimir Ilyich master of industrial training

Sedelnikovo, Omsk region, 2013

Visual control during gas welding works.

Test.

Each question has one or more correct answers. Choose the right one.

1. When is a welder qualified?

a) Together with the performance of welding work.

b) Before welding.

c) After completion of welding work.

How do you determine the brand of filler wire if there is no tag on the coil?

a) In appearance.

b) By melting.

c) You will not decide on your own.

Is it necessary to strip the filler wire?

a) Mandatory.

b) Not required.

c) Doesn't matter.

How do you make sure that the weld assembly is correct?

a) by eye.

b) Rely on the locksmiths who completed the assembly.

c) I will check the conformity of the welding technology of structural elements.

At what width is the metal surface adjacent to the edges cleaned before welding?

a) Not less than 5 mm.

b) Not less than 15 mm.

c) Not less than 20 mm.

Is it necessary to familiarize yourself with the welding technology of the product before welding?

a) Yes.

b) No.

c) Depending on the circumstances.

How can you check if the number of tacks is correct?

a) Determine approximately.

b) Check on welding technology.

c) The more, the stronger.

Why is a weld inspection performed?

a) To fix a defect.

b) To check their actions in the process of making a welded joint.

c) For both.

9. What does the weld inspection area include?

a) Seam along the entire length.

b) Seam on both sides and adjacent areas.

c) Both.

10. What is the purpose of preliminary control?

a) Prevention of the formation of defects in the weld
connection.

b) Saving time for welding.

c) Detection of defects in a welded joint.

Sample response:

question
answer

Test evaluation criteria:

Rating "excellent" 9-10 correct answers or 90-100% of the 10 proposed questions;

Rating "good" 7-8 correct answers or 70-89% of the 10 proposed questions;

Grade "satisfactory" 5-6 correct answers or 50-69% of 10 proposed questions;

Evaluation is unsatisfactory» 0-4 correct answers or0-49% of 10 offered questions.

Bibliography

Lavreshin S.A. Industrial training of gas welders: textbook. allowance for the beginning prof. Education - M .: Publishing Center "Academy", 2012.
Guskova L.N. Gas welder: worker Notebook: textbook. Allowance for the beginning. prof. Education - M .: Publishing Center "Academy", 2012.
Yukhin N.A. Gas welder: textbook. allowance for the beginning prof. Education - M .: Publishing Center "Academy", 2010.
G.G. Chernyshov. Handbook of electric and gas welder and gas cutter: textbook. allowance for the beginning prof. Education - M .: Publishing Center "Academy", 2006.
A.I. Gerasimenko "Fundamentals of electric and gas welding", Tutorial- M: JIC "Academy", 2010.
Maslov V.I. Welding work. Proc. for the beginning prof. Education - M .: Publishing Center "Academy", 2009.
Kulikov O.N. Occupational safety in the production of welding works: textbook. allowance for the beginning prof. Education - M .: Publishing Center "Academy", 2006.

Non-destructive testing (ND)- technological control of the reliability of the parameters of the object or its elements. When it is carried out, the object under study is not taken out of operation, it is not dismantled.

Non-destructive testing is used to diagnose buildings and structures, as well as for complex technological equipment. The non-destructive testing technology is safe and essential element industrial safety expertise. Thanks to non-destructive testing, technical safety is ensured at any facilities.

Ultrasonic control method

One of the main methods of non-destructive testing is the ultrasonic testing method (UT).
Ultrasonic method (UC) - based on the study of the process of propagation of ultrasonic vibrations with a frequency of 0.5 - 25 MHz in controlled products using special equipment - an ultrasonic flaw detector

The method of ultrasonic non-destructive testing is the emission and subsequent acceptance of reflected ultrasonic vibrations using an ultrasonic flaw detector and a piezoelectric transducer (s) and analysis of the data obtained in order to determine the presence of defects, as well as their equivalent size, shape (volumetric / planar), type ( point / extended), depth of occurrence, etc.

Application
The ultrasonic method is applicable during the manufacture of control objects, during their production tests, during technical examination, and also, directly, during operation.

Who is a flaw detector?

Defectoscopist is a specialist in non-destructive testing. The duties of a flaw detectorist include diagnostics of objects, as well as their parts (assemblies) in order to identify various defects. The name of the profession alone suggests that the profession of a flaw detectorist is very responsible, multidisciplinary, and not easy. A specialist in the ultrasonic method of non-destructive testing must confidently work with expensive and complex equipment, have extensive technical knowledge, know the standards, norms of flaw detectorists, regulations and various kinds of documentation.

Flaw Detector Certification

Certification (certification) of personnel for non-destructive control methods at I, II and III qualification levels passes in accordance with the requirements.

To accurately calculate the cost of attestation, you must select the methods and objects for which you need to study.

Basic methods and objects of non-destructive testing (NDT)

Defectoscopy methods:

- based on a phenomenon called acoustic emission. When acoustic waves arise and propagate during the deformation of a stressed material or the outflow of gases and other processes, elastic oscillations of acoustic waves arise, the data of which are used to determine the formation of defects at the initial stage of structural failure. Due to the movement of the medium, it is possible to use AE for the diagnostics of processes and materials, such as the criterion of material integrity;
- based on the study of the process of propagation of ultrasonic vibrations with a frequency of 0.5 - 25 MHz in controlled products using special equipment - an ultrasonic flaw detector;
Magnetic (MK)- based on interaction analysis magnetic field with a controlled object;
Electrical (EC)- based on the registration of the parameters of the electric field interacting with the controlled object or arising in the controlled object as a result of external influence;
Eddy current (VC)- based on the analysis of the interaction of the external electromagnetic field of the eddy current transducer with the electromagnetic field of eddy currents induced in the controlled object;
Radio wave (RVK)- based on registration of changes in the parameters of electromagnetic waves of the radio range interacting with the controlled object;
Thermal (TC)- based on registration of changes in thermal or temperature fields of controlled objects caused by defects;
Optical (OK)- based on registration of the parameters of optical radiation interacting with the controlled object;
- based on the registration and analysis of penetrating ionizing radiation after interaction with a controlled object. The word "radiation" may be replaced by a word denoting a specific type of ionizing radiation, such as x-rays, neutrons, etc.;
penetrating substances- based on the penetration of substances into the defect cavities of the controlled object. There are several types of this method, for example, “capillary (PVC)”, or “leak detection (PVT)”, which is used to detect through defects;
- based on visual inspection and quality control of welds, preparation and assembly of workpieces for welding. The purpose of this inspection is to identify dents, burrs, rust, burns, sagging and other visible defects. This method precedes other methods of flaw detection and is basic;
Vibordiagnostic (VD) - based on the analysis of the vibration parameters that occur during the operation of the controlled object. Vibration diagnostics is aimed at troubleshooting and assessing technical condition object of vibration-diagnostic control.

Defectoscopy objects:

1. Objects of boiler supervision

1.1. Steam and hot water boilers
1.2. Electric boilers
1.3. Vessels operating under pressure over 0.07 MPa
1.4. Steam and hot water pipelines with operating steam pressure over 0.07 MPa and water temperature over 115°С
1.5. Pressure chambers

2. Gas supply systems (gas distribution)

2.1. Outdoor gas pipelines
2.1.1. External gas pipelines steel
2.1.2. External polyethylene gas pipelines
2.2. Internal gas pipelines steel
2.3. Parts and assemblies, gas equipment

3. Lifting facilities

3.1. Cranes
3.2. Lifts (towers)
3.3. Cableways
3.4. Funiculars
3.5. Escalators
3.6. elevators
3.7. Pipelay Cranes
3.8. Loader cranes
3.9. Lifting platforms for the disabled
3.10. Crane ways

4. Mining facilities

4.1. Buildings and structures of surface complexes of mines, processing plants, pelletizing plants and sinter plants
4.2. Mining hoists
4.3. Mining transport and mining equipment

5. Objects of the coal industry

5.1. Mining hoists
5.2. Main ventilation fans
5.3. Mining transport and coal preparation equipment

6. Oil and gas industry equipment

6.1. Well drilling equipment
6.2. Well operation equipment
6.3. Well completion and workover equipment
6.4. Equipment for oil and gas pumping stations
6.5. Oil and gas pipelines
6.6. Tanks for oil and oil products

7. Equipment of the metallurgical industry

7.1. Metal structures technical devices, buildings and structures
7.2. Process gas pipelines
7.3. Pins of iron carriers, steel ladles, metal-pouring ladles

8. Equipment for explosive and chemically hazardous industries

8.1. Equipment for chemical, petrochemical and oil refining industries operating under pressure up to 16 MPa
8.2. Equipment for chemical, petrochemical and oil refining industries operating under pressure over 16 MPa
8.3. Equipment for chemical, petrochemical and oil refining industries operating under vacuum
8.4. Storage tanks for explosive and toxic substances
8.5. Isothermal storage
8.6. Cryogenic equipment
8.7. Ammonia refrigeration equipment
8.8. Furnaces
8.9. Compressor and pumping equipment
8.10. Centrifuges, separators
8.11. Tanks, containers (barrels), cylinders for explosive toxic substances
8.12. Process pipelines, steam and hot water pipelines

10. Objects of storage and processing of grain:

10.1. Blowers (air turbocompressors, turboblowers).
10.2. Fans (centrifugal, radial, VVD).
10.3. Hammer crushers, roller mills, entoleitors.

11. Buildings and structures (construction objects)

11.1. Metal constructions
11.2. Concrete and reinforced concrete structures
11.3. Stone and reinforced masonry structures

Learn to be a flaw detector

Of course, the work of a flaw detectorist should be based on extensive knowledge that can be obtained by completing flaw detector courses. Training in the profession of a defectoscopist in Moscow is carried out by special independent bodies for the certification of personnel of the non-destructive testing system. After graduating, the certification of a flaw detectorist is carried out, according to the results of which a certificate of a flaw detector engineer is issued. Our company will help you and your employees learn to be a flaw detector various kinds, in this case, an ultrasonic NDT flaw scopist, without interruption of production.

Why is certification of a flaw detector needed?

According to, all non-destructive testing specialists (defectoscopists) must undergo certification when conducting control using the methods established by clause 17 at the facilities established by Appendix 1.

Certification of their specialists should be carried out by enterprises and organizations engaged in non-destructive ultrasonic testing during technical diagnostics, repair, reconstruction of buildings and structures, as well as their parts and technical devices on production facilities associated with increased risk. Also, organizations involved in certification, advanced training of personnel must undergo certification in special independent bodies for the certification of personnel of the non-destructive testing system.

3 levels of flaw detector qualification:

I level of qualification— NDT specialist with skills, knowledge and skills in accordance with paragraph 1.2 of Appendix 4.

A NDT specialist of qualification level I can perform work on non-destructive testing by a certain NDT method, of certain objects, in accordance with the instructions, strictly observing the NDT technology and methodology and under the supervision of personnel with a higher qualification level than his.

The duties of a level I ultrasonic flaw detector include:

setting up the equipment that is used to carry out NDT by the appropriate method;
performance of NDT by the method for which it is certified;
description of the results of observation and control.

Specialist of I qualification level can not carry out an independent choice of the NDT method, equipment, technology and control mode, evaluate the results of control.

II level of qualification— NDT specialist with knowledge, skills and abilities in accordance with paragraphs 2.2 and 2.3 of Appendix 4.

NDT specialist of qualification level II can perform work on non-destructive testing, has sufficient qualifications to manage NDT in accordance with regulatory and technical documentation, to select the method of control, limit the scope of the method. Adjusts the equipment, assesses the quality of an object or element in accordance with the documents, documents the results obtained, develops instructions and various documents for specific products in the field of its certification, prepares and supervises Level I specialists. A specialist of the II level of NDT qualification makes a choice of technology and means of control, draws a conclusion on the results of control, which is carried out by him or a specialist of NDT of the I level.

III level of qualification— NDT specialist with knowledge, skills and abilities in accordance with paragraph 3 of Appendix 4.

The NDT specialist of the III level of qualification possesses the qualification necessary to manage any operations according to the NDT method, according to which he is certified, makes an independent choice of methods and methods of NDT, personnel and equipment. Supervises the work of personnel of levels I and II, and performs the work that is the responsibility of these levels. Controls and approves technological documentation developed by Level II specialists. Engaged in the development of methodological documents and technical regulations on NDT, as well as the evaluation and interpretation of the results of control. Participates in the training, certification of personnel at levels I, II, III, if authorized by an Independent body. He inspects the work performed by personnel of I and levels, is engaged in the choice of technology and control tools, draws a conclusion on its results, which he performed himself, or a specialist of I level under his supervision.

There are also various ranks of flaw detectorists, which they receive directly from the enterprises where they work.

You can be trained regardless of what qualifications you already have at the moment. If you already have work experience in the profession, and you want to upgrade your status to a grade 6 flaw detectorist, you need to undergo advanced training for flaw detectors. For specialists with insufficient experience and knowledge, there are courses where the professional training of flaw detectorists takes place, where you can learn to become a flaw detectorist from scratch.

IMPORTANT

In order to engage in non-destructive testing activities, an employee you need to get a doctor's note therapist and ophthalmologist, about the state of health.

List of documents for certification of personnel in the field of non-destructive testing (defectoscopist using the ultrasonic NDT method):

Registration card with the signature of the candidate (please indicate work experience)
Statement of consent to the processing of personal data
Application
Certified copy of education document
A document confirming the practical experience of work on the declared NDT method
Health certificate (conclusion of the therapist and ophthalmologist)
Information about the work carried out by the candidate for Last year(except for candidates applying for Level I)
Originals of previously issued credits, for reissuance (qualifying + PB)
Photo 4 pcs
Cooperation Agreement

Validity attestation of a flaw detector operator according to the ultrasonic NDT method I, II levels - 3 years, III level - 5 years from the date of certification.

Priceflaw detector certificates calculated only on the application, based on what work and activities will be attested!

non-destructive control is a continuous quality control of objects, after which they can be used for their intended purpose. The reliability of control is ensured by three main factors:

Organization of the control process; technical means; the human factor.

At the same time, effective control systems should be provided at each of the stages: manufacturing - operation - repair . High reliability and reliability of control can only be ensured by automating it, including the processing of information using computer technology and the issuance of a document with a conclusion on the quality of the object. To date, there is an active renewal of the fleet of flaw detectors.

Defects may be different type and determine its technological characteristics, for example:

Discontinuity, structural heterogeneity, size deviation from nominal, etc.

Regardless of the type, defects are divided into three kind , which determines its operational characteristics: critical (inadmissible, acutely defective) - it is impossible, unacceptable or unsafe to use the product; significant - significantly affecting the operational characteristics of the object, but an acceptable defect; insignificant.

Ultrasound. Types of ultrasonic waves. Characteristics of ultrasonic waves

Ultrasound is a process of propagation of mechanical vibrations of medium particles with a frequency of 20 kHz to 1000 MHz, accompanied by energy transfer and not accompanied by substance transfer. In this case, individual particles of matter oscillate with a certain amplitude BUT(maximum deviation from the equilibrium position) around their equilibrium positions. The time it takes to complete a full cycle of oscillations is called the period ( T). The oscillatory motion of individual particles is transmitted and causes ultrasonic (acoustic) waves due to the presence of elastic bonds between adjacent particles. Elasticity- the property of the particles of the medium to return to their original position. A wave in which the oscillations of individual particles occur in the same direction as the wave propagates is called longitudinal. A longitudinal wave is characterized by the fact that the medium alternates areas of compression and rarefaction, high and low pressure. Longitudinal waves can propagate in solids, liquids and gases, that is, in any media. Only longitudinal waves can propagate in liquids and gases. A wave in which the oscillations of individual particles occur in a direction perpendicular to the direction of propagation is called transverse or shear. Transverse waves can propagate only in solid media. The main characteristics of ultrasound are propagation speed (C), wavelength ( ), intensity (I), frequency (f) and wave type. Frequency is the reciprocal of the period (T) and it shows how many oscillations occur per unit time (second). The speed of the ultrasonic wave depends on physical properties medium in which it propagates and is different for different types of waves. For metals, the speed of the longitudinal ultrasonic wave is approximately twice the speed of the transverse ultrasonic wave.

The intensity of the ultrasound. attenuation of ultrasound.

When propagating, an ultrasonic wave carries a certain energy in the direction of its movement. The amount of energy carried by a wave per unit of time through a unit area perpendicular to the direction of its propagation is called wave intensity ( I ) . Wave intensity I is proportional to the square of the particle oscillation amplitude ( I BUT 2). In practice, the ratio of the amplitudes of the electrical signals of the transducers is measured (we will denote by letters U 1 And U 2 ), which in turn are proportional to the particle vibration amplitudes BUT 1 and BUT 2. The unit of measure in this case is the decibel. As the wave propagates, even in a strictly defined direction without any divergence, its intensity decreases. The decrease in wave intensity is called damping ultrasound. The damping of the wave occurs according to the exponential law. The attenuation of ultrasonic vibrations is due to two physical processes: takeover Andscattering . Therefore, the attenuation coefficient can be written:  =  absorption +  rass. At absorption the mechanical energy of particle vibrations goes into t thermal. This occurs due to internal friction and thermal conductivity of the medium. Absorption is most pronounced in liquids, gases and glasses. The attenuation coefficient for a given material increases with increasing ultrasound frequency and temperature. This is explained by the fact that the fraction of energy converted into heat due to internal friction forces is the same within one oscillation cycle. Since the number of oscillation cycles per unit time increases with an increase in the ultrasonic frequency, this leads to an increase in losses due to the conversion of ultrasonic energy into heat. Scattering of ultrasound can be caused by the presence of grains in the material of various components (for example, ferrite, graphite), different orientations of crystal grains, as well as the presence of pores or foreign inclusions. An increase in US scattering occurs in welded joints, the structure of which is changed by heating. This makes it difficult to control them by the mirror-shadow method.

Normal incidence of ultrasonic waves on the interface between media. Reflection and transparency coefficients.

When an ultrasonic wave is normally incident on the interface between two media, part of the wave energy is reflected from the interface, while the other part passes through it. The energy distribution of the reflected and transmitted waves depends on the mechanical characteristics of the adjacent materials: wave speed Andmedium densities. Intensity reflected wave  neg determined reflection coefficientR=  neg /  pad , where  pad –incident wave intensity. The reflection coefficient depends on the characteristics of the media R=( 1 FROM 1 – 2 FROM 2 /  1 FROM 1 +  2 FROM 2 ) 2 . Likewise, transmitted wave intensity  past is also a fraction of the intensity of the incident wave, and the value of this fraction can be determined using the coefficient D – transparency coefficient (passing) D =  past /  pad . Wherein R+ D=1 or R+ D=100%. As can be seen from the formula, more difference between the acoustic impedances of the media, the greater the reflection coefficient R and less, respectively, the transparency coefficient D. For example, the steel-air interface has a large difference in specific acoustic impedance (  STEEL = 45,  AIR = 0.00075) and, as a result, the reflection coefficient R is practically equal to 1 (100% of the wave energy is reflected), and the transparency coefficient, respectively, will be zero: D 0. Therefore, when an ultrasonic wave from steel or other material falls on the boundary with air, the wave will not be able to pass through it, but will be completely reflected. For the passage of ultrasonic vibrations from the piezoelectric transducer to the controlled product and back, it is necessary to introduce a liquid layer between them, which displaces air, and so on. the air-material interface disappears. On the other hand, the property of ultrasonic waves to be reflected from the boundaries of media with different acoustic characteristics is used to detect defects such as discontinuity: pores, cracks filled with gas ( R= 1) or slag and other inclusions (0  R  1).

Oblique incidence of ultrasonic waves on the interface between two media, Snell's law. critical corners.

In the case of oblique incidence, three phenomena can occur at the interface between two media with different ultrasonic wave velocities: reflection, refraction and transformation waves. reflection called the phenomenon in which a wave that has fallen on the interface between two media changes its direction of propagation in the same medium. Refraction – this is a change in the direction of propagation of an ultrasonic wave when passing through the interface between two media . Transformation called the transformation of waves of one type into waves of another type, occurring at the interface between media. Transformation can occur both when a wave is reflected, and when it is refracted.

It follows from the law of reflection and refraction that the angle of reflection of a wave of the same type as the incident one is always equal to the angle of incidence of the wave. When passing through the interface between media having the same velocities, the angle of refraction will also be equal to the angle of incidence. For other occasions corners refraction and reflection of waves will always be the same more, how above speed propagation of these waves. If the angle of incidence  is in the range from 0º ... 10º, then the intensity of the refracted transverse wave ( C t 2) is insignificant, and thus, practically only a longitudinal wave can be introduced into the tested product. For example, to introduce a longitudinal wave into a product at an angle  l 2 = 18º angle of incidence  \u003d 8º, and in direct dual-combined transducers, the angle of incidence  is 0º ... 4º. With an increase in the angle of incidence  all other angles also increase. The angle of incidence at which the angle of refraction or reflection of any wave becomes equal to 90 is called critical angle. So for some value  =  КР1 angle of refraction of the longitudinal wave  l 2 approaches 90 0 , and it begins to slide along the interface between the media. The smallest angle of incidence of a longitudinal wave at which a longitudinal wave does not penetrate the second medium is called first critical angle KR1. The speed of its propagation and the nature of the displacement of particles are similar to the characteristics of a longitudinal wave, but this wave quickly decays due to the splitting of a transverse wave from it at an angle of 34º. The set of waves propagating in this case is called head wave. With a further increase in the angle of incidence  there comes a moment when the angle of refraction of the transverse wave  t 2 approaches 90 0 and it does not penetrate into the second medium, but slides along the interface. The smallest angle of incidence of a longitudinal wave at which a transverse wave will not penetrate into the second medium is called second critical angle KR2. The values of the first and second critical angles can be calculated from the corresponding expressions: sin  WP1 = C l 1 / C l 2 , sin  WP2 = C l 1 / C t 2 . So for the plexiglass–steel interface  KR1 27º,  КР2 55º and slightly deviates from these values depending on the steel grade and ambient temperature. Thus, at angles of incidence of a longitudinal wave on the interface at angles  KR1     КР2, only a transverse wave will enter the volume of a solid body, and at angles of incidence    КР2 body waves will not be excited in the second medium. In order to excite only a transverse wave in the controlled product, the angle of incidence must be chosen  KR1     KR2.

Emission and reception of ultrasound. Materials used for the manufacture of piezoelectric plates. Characteristics of piezoelectric plates.

At present, the greatest application for the emission and reception of ultrasound in flaw detection is piezoelectric effect . The effect is that the deformation of the crystals of some materials ( piezoelectrics) causes the appearance of electric charges on its faces. If electrodes are applied to a plate of such a material and connected to a sensitive device with the help of conductors, it turns out that when the plate is compressed between the electrodes, an electric voltage of a certain magnitude and sign arises. When the plate is stretched, stress also arises, but of the opposite sign. The phenomenon of the appearance of electric charges on the surfaces of the plate during its deformation is called direct piezoelectric effect. There is also the opposite phenomenon, which consists in the fact that if an electric voltage is applied to the electrodes of the plate, its dimensions will decrease or increase depending on the polarity of the applied voltage. When the sign of the applied stress changes with a certain frequency, the plate is compressed and stretched with the same frequency. This phenomenon of changing the size of the plate under the influence of an electric field is called reverse piezoelectric effect. Thus, with the help of a piezoelectric plate, it is possible to convert electrical vibrations into ultrasonic ones (reverse piezoelectric effect - for emitting ultrasound) and, conversely, ultrasonic ones into electrical ones (direct piezoelectric effect - for receiving ultrasonic vibrations). It is important to note once again that the amplitude of the electrical signal on the electrodes (for direct and inverse piezoelectric effects) is proportional to the amplitude of the mechanical vibrations of the particles, which makes it possible to measure (compare) the ultrasound intensity. For excitation and registration (radiation and reception) of ultrasonic vibrations, piezoelectric transducers (PTs) are used in which active are piezo elements- plates made of a material with piezoelectric properties with metal electrodes deposited on their surface. Piezoelectric elements for ultrasonic flaw detection are most often made of piezoceramics: lead zirconate titanate (TsTS-19) and barium titanate (TBA). Piezoceramic wafers are cheaper and have a higher conversion factor than natural crystals such as quartz. The temperature above which the plates lose their piezoelectric properties is called temperature (point ) Curie . Plates from TsTS-19 lose their piezoelectric properties at a temperature of 290 0 C, and from TBC at a temperature of 120 0 C. The main operational characteristics of the transducers: natural resonant frequency, quality factor, length of the near zone, opening angle, radiation pattern determined by the geometric dimensions and shape of the plate. Own resonant (working) frequency thin piezoelectric plate is determined by the speed of sound in the piezomaterial and its thickness.

Design of direct, inclined, RS and combined transducers. The structure of their symbol.

Piezoelectric transducers (PETs) are used to emit and receive ultrasonic vibrations. The main elements of the probe: 1 - piezoelectric element, 2 - damper and filling mass, 3 - lead wires, 4 - connector, 5 - housing, 6 - protector, 7 - prism, 8 - controlled object, 9 - electroacoustic screen. The piezoelectric element (1) serves to convert electrical vibrations into acoustic ones when ultrasound is excited and (or) back when it is received. For a direct probe (and in some designs of separate-combined (RS) probes), it is separated from the controlled product (8) by a protector (6), which serves to protect the piezoelectric element from abrasion and mechanical damage. In inclined and some PC PET designs, the role of the protector is performed by the prism (7), which simultaneously sets the angle of incidence, i.e. determines the angle of ultrasound input into the product. The piezoelectric element is connected to the connector (4) by lead wires (3). The damper (2) is used to create short impulses. In addition, together with the filling mass, it gives the converter additional mechanical strength. All elements of the probe are usually placed in the housing (5). Direct probes are used to introduce longitudinal waves into the product, and inclined probes are used as longitudinal (at prism angles up to the first critical), but more often transverse or surface waves. Combined probes have more than two piezoelectric elements with different ultrasound input angles. The piezoelectric transducer is marked with the letter P and a set of numbers, for example, P 121-2.5-50. In this case, the first digit shows the method of introducing ultrasound into the product and can be: 1 - contact, 2 - immersion, 3 - contact-immersion, 4 - non-contact. The second digit refers to the design of the probe and can be: 1 - straight, 2 - inclined, 3 - combined. The third digit shows how the probe is connected to the flaw detector and can be: 1 - combined circuit, 2 - separate-combined, 3 - separate. This is followed by the value of the operating frequency in megahertz, the angle of input (for straight lines it may not be indicated) and additional information from the manufacturer about the design features, materials used, model number. On any probe, the serial number must be indicated

The concept of the near and far zone. Directional diagrams of ultrasonic emitters.

The energy of an ultrasonic wave is not emitted uniformly in all directions, but within a narrow, slightly divergent beam. Near the emitter, the wave propagates without divergence, this zone is called near zone or Fresnel zone. Outside the near zone begins distant zone or the Fraunhofer zone. In this zone, the ultrasonic field generated by a circular plate can be represented as a truncated cone. With an increase in the frequency of ultrasound, the angle 2  R, which characterizes the opening of the main lobe of the radiation pattern of the emitter of a given diameter, will decrease. At an ultrasound frequency of 2.5 MHz and an emitter diameter of 2 but= 12 mm, the length of the near zone in steel is approximately 15 mm, and half the opening angle  p does not exceed 14º. IN near field intensity ultrasonic field, both along the beam and along its cross section unevenly distributed and varies from point to point. IN far field– intensity smoothly falls, both along the beam and along its cross section. The locus of points of maximum field intensity in the far zone of the emitter and its continuation in the near zone is called acoustic transducer axis . Directionality of the field, or change in the intensity of ultrasonic testing in the far field depending on the angle  p between the direction of a given beam and the acoustic axis at a constant distance from the radiator can be displayed using the so-called radiation patterns . If the piezoelectric element has the shape of a disk, then the shape of the main lobe of the directivity pattern of a direct probe is symmetrical about the axis and looks like a "mace". The central part of the radiation pattern, within which the field amplitude decreases from unity to zero, is called main lobe . About 85% of the radiation field energy is concentrated within the main lobe. Outside the main lobe, the radiation pattern may have side lobes

Methods of ultrasonic flaw detection: impulse echo method, shadow, mirror-shadow and mirror methods.

Most ultrasonic flaw detectors are pulsed. Their principle of operation is based on sending ultrasonic pulses into the product and receiving their reflections from discontinuities or structural elements of products. Shadow Method control involves access to the product from two sides (Fig. 2.2) and is implemented with a separate circuit for switching on the probe. In this case, ultrasound is emitted by one probe (I), passes through the controlled product and is received by another probe (P) on the other side. A sign of a defect in the shadow method is a decrease below the threshold level or the disappearance of the signal transmitted through the controlled product. The method is highly sensitive, but does not provide information about the depth of the defect. The magnitude of the defect can be judged from the degree of attenuation of the transmitted signal. In addition, other factors also influence the decrease in the signal amplitude during shadow sounding: surface roughness, ultrasound attenuation, beam divergence, transducer misalignment. At mirror-shadow method (ZTM) emitter and receiver are located on the same side (contact). The mirror-shadow method can be implemented either with one direct or two tilted transducers. When working according to the first scheme in rail flaw detection, a separate-combined transducer is more often used. The receiver registers the signal reflected from the opposite side (bottom), which is called the "bottom" signal. Ultrasound passes through the product twice, which increases the sensitivity of the control. You can also work on the second and subsequent bottom signals, and the sensitivity will increase in this case. Unlike the shadow method, MTM does not require two-sided access to the product, but two plane-parallel surfaces are required. When using direct probes, it also does not provide information about the depth of the defect. A sign of a defect in the ETM control is the disappearance of the bottom signal or its weakening below the threshold level. The magnitude of the defect can be judged from the degree of attenuation of the back- ground signal. The detectability of a defect does not strongly depend on its orientation with respect to the acoustic axis. The echo method of ultrasonic flaw detection is based on sending short ultrasonic signals (probing pulses) into the product and recording signals (echo signals) reflected from the detected defects..When checking with a direct transducer, along with an echo signal from a defect, a back ground signal may be present on the screen. It is possible to control by a beam reflected from the opposite surface (Fig. 2.4 c) as well as by repeatedly reflected beams. A sign of a defect in the echo testing method is the appearance in the testing zone of an echo signal with an amplitude above the ASD triggering threshold at a given sensitivity of the flaw detector. In some cases (for example, a crack with a mirror surface oriented at an angle other than zero to the acoustic axis of the transducer), the echo method may not detect even a strongly developed defect at all. However, if it is known where the signal reflected from the defect will be directed, the receiver can be placed in its path and this signal can be registered. This method of control is called mirror

The main measured characteristics of the defect in the pulse echo method: the coordinates of the defect, the conditional dimensions of the defect. Types of surfaces reflecting ultrasound.

The principle of measuring the coordinates of the reflector in the echo method of ultrasonic testing is to measure the time of arrival of the echo signal - t after the probing pulse and recalculating it into the appropriate coordinate. When working with a direct probe, only the depth of the reflective surface of the defect is determined - H. It is calculated by time t echo signal arrival. For an inclined probe, two coordinates are determined: H is the depth of the reflective surface of the defect and L is the distance from the beam exit point to the projection of the reflective surface of the defect on the surface of the product, which is being scanned. The value of the depth H and distance L are determined at the position of the probe, in which the echo signal has the greatest value. When a defect is detected using ultrasonic testing methods, it is impossible to measure its true dimensions, but they can be approximately estimated. These defect sizes are called conditional, they are, as a rule, larger than the true ones and depend on many factors: configuration, orientation, depth of the defect, method of measurement, sensitivity of the flaw detector, as well as the radiation pattern of the probe. Knowing the conditional dimensions helps to assess the danger of the defect and decide on the possibility of further operation of the object. The conditional linear dimensions of the defect include: conditional length– Δ L; conditional height– Δ H; conditional width– Δ X. In rail flaw detection, the concept is also used conditional length of the defect along the length of the rail. When working with inclined probes, all three nominal dimensions can be measured.

The concept of sweeps of type A and B.

Design and purpose of the standard sample SO-3R. The main parameters of rail control in the pulse echo method. The order in which they are configured.

Federal Agency for Education Russian Federation Far Eastern State Technical University(FEPI named after V.V. Kuibyshev) I approve: Deputy Chairman of the Presidium of the Far Eastern Educational and Methodological Center Professor ___________________ A.A. Belousov "______" ______________ 2007. Control and measuring materials for assessing the level of knowledge of students of the specialty "Acoustic devices and systems" in the discipline "Non-destructive methods of control" Developed by Associate Professor of the Department of Civil Aviation Salnikova E.N. Vladivostok 2007 Discipline "Non-destructive testing methods" is one of the disciplines of specialization in the preparation of students in the specialty "Acoustic devices and systems". Non-destructive testing methods (NMC), or flaw detection, is a generalized name for the methods of testing materials (products) used to detect discontinuities or homogeneity of the macrostructure, deviations in the chemical composition and other purposes that do not require the destruction of samples of the material and / or product as a whole. Quality improvement industrial products, increasing the reliability and durability of equipment and products is possible subject to the improvement of production and the introduction of a quality management system. Important criteria High Quality parts of machines, mechanisms, devices are physical, geometric and functional indicators, as well as technological signs of quality, for example, the absence of unacceptable defects; correspondence of physical and mechanical properties and structure of the base material and coating; compliance of geometric dimensions and surface finish with the required standards, etc. Wide application of non-destructive testing methods that do not require sample cutting or destruction finished products, allows you to avoid large losses of time and material costs, provide partial or complete automation of control operations while significantly improving the quality and reliability of products. Currently none technological process obtaining responsible products is not introduced into the industry without an appropriate system of non-destructive testing. The discipline "Non-destructive testing methods" is designed to prepare a graduate to solve the following professional tasks in the field of design and engineering: development of functional and structural diagrams of devices and systems with the definition of the physical principles of operation of devices, their structures and the establishment of requirements for individual blocks and elements; assessment of the manufacturability of design solutions, preparation of technical documentation, including operating instructions, test programs, specifications, etc., as well as in the field of production and technological activities: development and implementation of technological processes and manufacturing methods, quality control of elements and assemblies of devices for various purposes. The discipline is read in the 9th semester in the amount of 51 hours. lectures on the working curriculum in 2002. and 34 hours. - as planned in 2005 The purpose of control and measuring materials is the current control of the assimilation of the material of the discipline "Non-destructive methods of control". According to working curricula discipline provides for the implementation of 8 express surveys after each of the main topics, 1 test, 2 tests - boundary and final, as well as 1 2 individual tasks. Upon successful completion of the IDZ, the student receives 4 points, the test - 3 points, each of the EE - 4 points, 1 test is estimated at 9 points, the final one - 12 points. Thus, a successfully studying student during the semester can score at least 60 points out of 100 total, provided by the point-rating system for assessing the development of the discipline, which corresponds to the minimum level that meets the requirements of GOS VPO No. 331 inf / SP specialty 200105. class time. When conducting express surveys, the student receives a sheet with an individual task, including 2-3 questions (depending on the topic), randomly selected by the teacher from the lists given in this development. During the test, the student is given a test form. We used both a closed form, which provides for the choice of the correct answer from several given ones, and an open one, in which an independent formulation of the answer is provided. When conducting a test, 1 student is given a form containing 14 questions formed by the teacher from the bank of questions to control 1-4 sections. KIM contains 10 options for tasks for WP1. The final control work includes 28 questions. 15 variants have been developed. The student is given 10 minutes to answer the EA, 20 minutes for the test, 40 minutes for WP1, and 1 hour 30 minutes for WP2. Instruction for the student When answering the question, the task does not need to be rewritten. You should write down the Surname, group, task number, question number and answer. To pass the test, it is enough to score 60% of the maximum possible number of points indicated in the test. To successfully pass the tests - correctly answer 8 out of 14 and 17 out of 28 questions. The report on the results of the check and the analysis of typical errors are carried out in the next lesson 3 Theme "Main types of NMC" Test No. 1 Development date 04/18/2006 Carefully read the beginning of the definition given in column 2, and select the correct ending in column 3. Mark the selected answer. In column 4, briefly justify your choice. Complete the table on the back of the sheet based on your answers. Enter your last name and group number. № Beginning of definition End of definition Brief justification for the answer 1 2 3 4 1 In accordance with ISO - a) the ability of products to meet 8402 "quality is customer requirements." b) a set of characteristics of an object related to its ability to satisfy conditional or implied needs. c) a set of product characteristics that affect its performance. d) all of the above. e) none of the above. 2 NMC mandatory a) the production of critical parts are used in and devices. b) production of units and parts of devices for long-term operation. c) any product. d) good insulating material. e) material with high electrical conductivity. f) studies of the structure of materials and defects. g) all of the above. h) none of the above. 3 Acoustic NMC a) surface defects. suitable for b) internal defects in the form of cracks. detection c) internal defects in the form of shells. d) subsurface defects. e) none of the above. e) all of the above. 4 Capillary NMC a) surface defects. suitable for b) internal defects in the form of cracks. detection c) internal defects in the form of shells. d) subsurface defects. e) none of the above - write your own answer. e) all of the above. 5 Visual-optical a) on the measurement of amplitude or phase methods are based on the transmitted light radiation. b) on the measurement of stimulated emission. c) on measuring the degree of polarization of the transmitted radiation. d) all of the above. e) none of the above - write your own answer. 4 6 Informative a) the amplitude of the transmitted radiation. parameter b) the amplitude of the scattered radiation. radio wave methods c) the amplitude of the reflected radiation. is d) all of the above. e) none of the above - write your answer 7 Defects in the wire a) NDT radiation methods. from non-ferromagnetic b) radio wave methods of NDT. material is best c) magnetic NDT methods. d) all of the above are detected. e) none of the above - write your answer 8 Defects in the wire a) capillary NMC. from ferromagnetic b) Magnetic NMC. material is best c) radio wave NMC. d) all of the above are detected. e) none of the above - write your answer 9 The most expensive of a) acoustic. NMK b) radiographic. c) capillary. d) all of the above. e) none of the above - write your answer 10 Basic requirements for Write your answer KO in acoustic testing methods 11 Basic requirements for KO in radiographic testing of cast products 12 List the advantages of destructive testing methods 13 List the main disadvantages of NMC Student of the group __________________ Full name ___________________________________ Question 1 2 3 4 5 6 7 8 9 10 11 12 13 13 Answer Result Scored _____________ maximum possible __61___---- Instructor ___________________ Date _____________ 5 Topic “Main types of CMI” Test No. 1 KEY Question 1 2 3 4 5 6 7 8 9 10 11 12 13 Total Answer B A, B, E E A D D D B, D B Result 5 5 5 5 5 5 4-5 3-5 4-5 5 5 3 3 61 6. Correct answer: Radio wave methods are based on registration of parameters of microwave electromagnetic waves with KO. 7. Correct answer: Acoustic, Eddy current. 8. Correct answer: Acoustic, Eddy current, Magnetic 9. Correct answer: Radiation and Leak detection. 10. When checking pipes with a diameter<=4 мм и толщиной > \u003d 1mm, it is necessary to clean the surface from dirt, exfoliating scale. 11. Requires bilateral access to KO, the absence of external defects exceeding the sensitivity of the control. 12.1. Tests usually simulate one or more operating conditions. Therefore, they are directly aimed at measuring operational reliability. 2. Tests are usually quantitative measurements of failure loads or life to failure under given loading and conditions. Thus, they provide numerical data useful for design purposes or for the development of standards or specifications. 3. The relationship between most destructive testing measurements and the measured properties of materials (especially under load simulating operating conditions) is usually direct. Therefore, disputes over test results and their significance for the operational reliability of the material or part are excluded. 13.1. Tests usually involve indirect measurements of properties that are not directly relevant in service. The relationship between these measurements and operational reliability must be proven in other ways. 2. Tests are usually qualitative and rarely quantitative. They usually do not provide the ability to measure failure loads and service life to failure, even indirectly. They can, however, detect a defect or follow the process of destruction. 3. Studies on special specimens and examination of operating conditions are usually required to interpret test results. Where an association has not been proven, and in cases where the possibilities of the technique are limited, observers may not agree on the assessment of test results. 6 Theme "Main types of NMC" Test No. 2 Development date 04/18/2006 Carefully read the beginning of the definition given in column 2, and select the correct ending in column 3. Mark the selected answer. In column 4, briefly justify your choice. Complete the table on the back of the sheet based on your answers. Enter your last name and group number. № Beginning of definition End of definition Brief substantiation of the answer 1 2 3 4 1 Quality control a) its working capacity. products is b) compliance of indicators of its quality in the verification of established requirements. c) compliance of indicators with operational safety requirements. d) all of the above. e) none of the above - your answer. 2 List the most important criteria for the quality of parts of machines, mechanisms, devices 3 Magnetic NMC a) surface defects. suitable for b) internal defects in the form of cracks. detection c) internal defects in the form of shells. d) subsurface defects. e) none of the above. e) all of the above. 4 Radio wave NMC a) surface defects. suitable for b) internal defects in the form of cracks. detection c) internal defects in the form of shells. d) subsurface defects. e) none of the above - write your own answer. e) all of the above. 5 Radiation methods a) based on the measurement of the amplitude or phase of the transmitted penetrating radiation. b) on the measurement of stimulated emission. c) on measuring the degree of polarization of the transmitted radiation. d) all of the above. e) none of the above - write your own answer. 6 Informative a) the amplitude of the transmitted radiation. parameter b) the amplitude of the scattered radiation. acoustic methods c) the amplitude of the reflected radiation. is d) all of the above. e) none of the above - write your answer 7 Defects in castings from a) NDT radiation methods. non-ferromagnetic b) radio wave NDT methods. material is best c) magnetic NDT methods. 7 are revealed d) all of the above. e) none of the above - write your answer 8 Defects in rubber a) capillary NMC. products are best b) Magnetic NMC. are detected c) radio wave NMC. d) all of the above. e) none of the above - write your answer 9 The most dangerous of a) acoustic. NMK for b) radiographic. serving c) capillary. personnel d) all of the above. e) none of the above - write your answer 10 Basic requirements for CR in leak detection testing 11 Basic requirements for CR in acoustic testing of cast products 12 List the main disadvantages of destructive testing methods 13 List the main advantages of NMC Student of the group __________________ Full name ___________________________________ Question 1 2 3 4 5 6 7 8 9 10 11 12 13 13 Answer Result Scored score _____________ maximum possible ___73_---- Instructor ___________________ Date _____________ 8 Topic “Main types of CMI” Test No. 3 Development date 04/18/2006 Carefully read the beginning of the definition, given in column 2, and choose the correct ending in column 3. Mark the selected answer. In column 4, briefly justify your choice. Complete the table on the back of the sheet based on your answers. Enter your last name and group number. № Beginning of the definition End of the definition Brief substantiation of the answer 1 2 3 4 1 Basic requirements, a) the ability to check the performance of products and products required for NMC. it b) the possibility of conducting quality control at all stages of manufacture, operation and repair. c) high reliability of control results. d) all of the above. e) none of the above - your answer. 2 List the main areas of application of NMC 3 Eddy current NMC a) surface defects. suitable for b) internal defects in the form of cracks. detection c) internal defects in the form of shells. d) subsurface defects. e) none of the above. e) all of the above. 4 Radiation NMC a) surface defects. suitable for b) internal defects in the form of cracks. detection c) internal defects in the form of shells. d) subsurface defects. e) none of the above - write your own answer. e) all of the above. 5 Thermal methods of NDT a) on the measurement of thermal fields of CO. are based b) on the measurement of the parameters of the elastic field of the SO. c) on the measurement of the temperature field of the operating object. d) all of the above. e) none of the above - write your answer. 6 Informative a) change in the thermal field of the object. thermal parameter b) the temperature field of the operating object. methods of NDT is c) change in the electric field interacting with the CO. d) all of the above. e) none of the above - write your answer 7 Defects in a) NDT radiation methods. multilayer b) radio wave NDT methods. dielectric c) magnetic NDT methods. 9 products best d) all of the above. are detected e) none of the above - write your answer 8 Defects in the sheets a) capillary NMC. steel up to 1 mm thick b) Magnetic NMC. best of all c) radio wave NMC. d) all of the above are detected. e) none of the above - write your answer 9 The most dangerous of a) acoustic. NMC for the environment b) radiographic. medium c) capillary. d) all of the above. e) none of the above - write your answer 10 Basic requirements for Write your answer CT when testing with eddy current NMC 11 Basic requirements for CR when acoustic testing of pipes 12 List the main advantages of destructive testing methods 13 List the main advantages of NMC Student of the group __________________ Full name ___________________________________ Question 1 2 3 4 5 6 7 8 9 10 11 12 13 13 Answer Result Score _____________ maximum possible ___67_---- Instructor ___________________ Date _____________ 10

federal agency railway transport

Federal State Educational Institution

Secondary vocational education

Penza College of Railway Transport

Non-destructive testing of components and parts,technical diagnostic systems

Test

Question number 1. General provisions non-destructive testing

Question number 2. Magnetic type of non-destructive testing

Question number 3. Tasks of tools and classification of technical diagnostic systems

Question number 1. General provisions of non-destructive testing

Technical diagnostics- a field of knowledge covering the theory, methods and means for determining the technical condition of objects (GOST 20911-89) (17).

Technical diagnostics- the process of establishing the technical condition of an object with an indication of the location, type and causes of defects and damage.

Technical diagnostic system PS is a set of objects, methods and means, as well as performers, which allows diagnosing according to the rules established by the relevant regulatory and technical documentation. This system is intended to solve the following tasks:

diagnosis(from the Greek "diagnosis" - recognition, definition) - assessment of the technical condition of the substation or assembly unit at the present time (in this case, the quality of manufacture or repair of wagons and locomotives is determined);

forecasting(from the Greek "prognosis" - foresight, prediction) of the technical condition in which the mobile unit will be after a certain period of operation (for example, at checkpoints Maintenance(PTO) of wagons, not only the technical condition is determined, but also the issue of the possibility of wagons going to the next PTO without failures is resolved);

genesis(origin, occurrence, formation process) - establishing the technical condition of the PS in the past (for example, before an accident, crash, other emergency events); the solution of problems of this type is called technical genetics. Diagnosis is performed at every stage life cycle PS: at the design stage, during production, in operation and during all planned types of repairs. The car, locomotive, assembly unit or part as objects of diagnostics (OD) experience operational impacts during their normal operation and test impacts from technical diagnostic tools (STD) that simulate the operating conditions of the substation close to operational ones. The technical condition of the OD can be judged by diagnostic parameters (DP).

Rice. one Structural scheme systems for technical diagnostics of wagons and locomotives.

Information from the STD, measuring and converting parameters according to a pre-developed diagnostic algorithm (AD), comes to the operator (O) to make a decision.

At the design stage of the PS, a mathematical model of the object to be diagnosed is developed, the tactics of health management are determined, the requirements for diagnosability and technology for its implementation are formulated, and a sequence of preventive and repair work at the facility is assigned.

According to the purpose, the diagnostic systems are divided into systems for checking the performance (whether a wagon, locomotive or assembly unit is working or not), correct functioning (whether the parameters of its operation correspond to a good technical condition), the presence of a defect (determining the location, type and type of defect, the reasons for its occurrence) .

Technical diagnostic systems are also divided into general (for assessing the technical condition of assembly units and parts), functional during the operation of cars, test (when STD ) and combined (a combination of functional and test diagnostic methods).

Question number 2. Magnetic type of non-destructive testing

The magnetic type of NC is based on the analysis of the interaction of the test object with a magnetic field and is applicable only to parts made of metals or alloys that can be magnetized. They control free parts or parts of parts that are open to access in order to detect surface or subsurface defects.

In railway transport, the following objects of rolling stock are subjected to magnetic control: parts of shock-traction and braking equipment, bogie frames of various models, assembled and by elements, kingpins, axles of wheel sets of all types, both assembled and in a free state, disks, comb and spokes of locomotive wheels, free rings of axle bearings, as well as inner rings pressed onto the axle journals, rims of gears and gears of the traction gearbox, shafts of generators, traction motors and gears assemblies, thrust rings, locking bars, springs, bolts, etc. P.

It is said that a force field exists in "empty" space if a force acts on an object located in this space. For example, a person constantly experiences the action of a gravitational field: wherever he is, the Earth attracts him with the same force in magnitude and direction.

For all force fields, the structure of the formula for determining the field strength is the same. It always contains the product of one or more quantities that characterize the body (mass, charge, speed, etc.) by a vector quantity that characterizes the field at the point where the body is located. This value is called tension fields. Each force field is created by those and only those bodies on which it can act. For example, any object, regardless of size, mass, color, etc., creates a gravitational field around itself, which attracts other objects along the line connecting their centers of gravity. Let's take another physical nature, electrostatic (Coulomb) field. We emphasize that the electrostatic field is more selective, it is created only by charged bodies, the charges of which can be both positive and negative, but the mass is always positive. But the construction of the formulas is the same: in order to obtain a force, it is necessary to multiply a certain value related to the body by the field strength at this point.

Force fields are described by lines of force. The main property of the field line of any field is that at any point through which it passes, the direction of the intensity vector coincides with the direction of the tangent to it at the same point, and the lengths of the vectors, i.e. the values of tensions at all points of the field line are the same. The field strength is greater in magnitude where the lines are thicker . By the totality of lines, one can judge not only the direction, but also the magnitude of the field strength at each point. A field whose intensity is the same at all points is called homogeneous. Otherwise, it is inhomogeneous.

A magnetic field is one of the types of force fields. But unlike electrostatic, it is even more selective - it acts only on moving charges. Stationary charged objects, even in the strongest magnetic fields, are not affected by any force. It becomes obvious that the "construction" of the formula for determining the force acting on a moving body in a magnetic field should be more complicated than the previous ones.

Magnetic testing methods can only be used for parts made of ferromagnetic materials. They are based on the detection or measurement of stray magnetic fields that occur on the surface of a magnetized part in places where there are violations of the integrity of the material or inclusions with a different magnetic permeability. This control method consists of the following technological operations: preparation of the product for control; magnetization of a product or part thereof; application of ferromagnetic powder (dry method) or suspension (wet method) to the surface of the product; surface examination and interpretation of control results; demagnetization. Preparation of products for control consists in its thorough cleaning. There are three ways of magnetization: pole (longitudinal), non-pole (circular) and combined.

With pole magnetization, electromagnets and solenoids are used. During magnetization, a large low voltage current is passed through the part. If the part is hollow, then the electrode magnetization method is used. The combined method is a combination of poleless and pole magnetization methods . With pole magnetization, a longitudinal field is formed, in which transverse cracks are detected. With non-pole magnetization, longitudinal defects (cracks, hairlines, etc.) and radial cracks on the end surfaces are revealed. With combined magnetization, the product is simultaneously affected by two mutually perpendicular magnetic poles, which makes it possible to detect defects in any direction. For the magnetization of products, alternating and direct, as well as pulsed current, can be used. As magnetic powders, magnesite (ferrous oxide Fe3O4) of black or dark brown color is used to control products with a light surface. Brown-red iron oxide (Fe2O3) is used to control products with a dark surface. Mild steel filings have the best magnetic properties. To control products with a dark surface, colored powders are also used. Liquid base for mixtures (suspensions) are organic oils. When preparing the mixture, usually 125-175 g of iron oxide powder or 200 g of sawdust are added to 1 liter of liquid. Depending on the magnetic properties material, control can be carried out by the residual magnetization of the product or in an applied magnetic field. In the first case, the powder is applied to the part with the flaw detector turned off, and in the second case, when it is turned on. In the presence of a defect, powder particles, settling in the area of the edges of the crack, outline its contour, i.e. show its location, shape and length. Parts with high residual magnetism can attract abrasive products for a long time, which can cause increased abrasive wear. Therefore, these parts must be demagnetized.

Question number 3. Tasks of tools and classification of technical diagnostic systems

Under the means of technical diagnostics is understood a complex technical means to assess the technical condition of the control object.

Depending on the tasks and scope, technical diagnostic tools can be classified according to different criteria.

From the point of view of the field of application, STD can be divided into regular and special. Regular STDs are mainly intended for functional diagnostics, i.e. for routine monitoring of the technical condition. These include stands, micrometric tools, indicators, flaw detectors, instruments for measuring various physical quantities. According to their purpose, STDs are divided into universal ( general purpose) and specialized. Universal STDs are designed to measure parameters (electric current, voltage, strength and induction of the magnetic field, spectral analysis vibration and noise, fault detection tools, etc.) technical condition of substations of various designs. Specialized STDs are created for diagnosing specific elements of machines, cars and locomotives of the same type. STD consist, as a rule, of sources of influence on a controlled object (with a test method), converters, communication channels, amplifiers and signal converters, blocks for measuring, decoding and recording (recording) diagnostic parameters, blocks for accumulating and processing information based on microprocessor technology, compatible with personal computer. From the point of view of mobility STD are divided into built-in and portable. Built-in STDs are assembled in the overall design of the test object (for example, heating sensors for axle bearings passenger cars) and are used for continuous monitoring of assembly units, the failures of which threaten the safety of train traffic or the technical condition of which can only be determined under working loads (parameters of a running diesel engine, compressor).

PAGE_BREAK--

External STDs are made in the form of stationary, mobile units, portable devices connected to the car during the control period.

According to the types of diagnostics, the methods and means of diagnostics are divided into functional and test ones. Functional methods consist in measuring the signals that occur during the operation of the PS or assembly units under normal operating conditions. With the test method, signals are generated as a reflection of the external influence of the diagnostic tool. Modern diagnostic installations are compact complexes of specialized computers, within which appropriate blocks are provided (the structure of D-U-computers).

There have been two trends in the construction of STD: in the form of multi-parameter structures and systems with in-depth decoding of information.

In the first case, a large number of different transducers are installed on the diagnostic object according to a certain scheme, with the help of which many parameters are recorded to assess the technical condition of the object. This approach requires a significant investment of time and reduces the probability of trouble-free operation of the diagnostic system.

The second trend is to install the minimum number of transducers, but a more in-depth analysis of the information received due to the selection of signals - interference and useful signals from the controlled object, on which a decision is made about its technical condition.

Modern STDs make it possible to implement the second trend, in which, despite the complication general scheme diagnostics, it is possible to achieve a significant reduction in material costs with high reliability of control. The main STDs used in operation and during scheduled types of wagon repairs are presented in the table.

To control cars in arriving trains, the equipment ARM-OV, an automated workplace for a car inspector, was developed.

The plan for the long-term development of the wagon economy provides for the use of highly efficient non-waste technologies for the maintenance and repair of wagons with the widespread use of automated diagnostic complexes for monitoring the technical condition of assembly units:

Automated non-contact complex for monitoring wheel sets of rolling stock on the go "Express-Profile";

Automated diagnostic complex for measuring the wheel pairs of cars on the approaches to the station "Complex";

System for determining the quality of loading wagons;

Automatic control device for wheels and axle slipping;

Integrated monitoring system for braked wheels, sliders, welds,

dents, uneven rolled products, small-sized ridge, wheel cracks;

Control system for open unfixed, deformed hatches and doors of freight cars;

Automated system detection of cars with negative dynamics (ASOOD) on the way to the station. The equipment of network maintenance points with automated diagnostic complexes will ensure the safe passage of trains weighing up to 14 thousand tons in increased warranty sections.

Literature

Non-destructive testing in the wagon industry. YES. Moikin.

2. Modern methods technical diagnostics and non-destructive testing of parts and assemblies of rolling stock of railway transport. Krivorudchenko V.F., Akhmedzhanov R.A.

3. Non-destructive testing in the wagon industry. YES. Moikin.

4. Car repair technology. B.V. Bykov, V.E. Pigarev.