RU2653663C1 - Rail electromagnetic-acoustic control device - Google Patents

Abstract

FIELD: defectoscopy.

SUBSTANCE: invention relates to the field of nondestructive testing in the implementation of ultrasonic contactless flaw detection methods to detect defects in rails at significant scanning speeds. Rail electromagnetic-acoustic control device contains a test wheel with a set of electromagnetic-acoustic transducers evenly placed in special depressions in the rim along the perimeter of the test wheel. Magnetic system of electromagnetic-acoustic transducers is made in the form of a biaxial trolley with the placement of solenoids on the axes of wheel pairs. Solenoids are connected by a magnetic chain with axes of wheel pairs. Wheels serve as poles of the electromagnet and at least one wheel of the cart on each rail is test, and the inductors of the electromagnetic-acoustic transducers are fixed in the wheel rim sealed.

EFFECT: efficiency of excitation of ultrasonic oscillations by a contactless method in a controlled rail increases at high scanning rates.

1 cl, 4 dwg

Description

The invention relates to the field of non-destructive testing when implementing ultrasonic non-contact (without the use of a contacting liquid) flaw detection methods for detecting defects in rails at significant scanning speeds.

Various means are used for flaw detection of a rail track: magnetodynamic, ultrasonic, eddy current, subsurface radar sounding, optical, etc. Magnetodynamic methods can work in all climatic zones under any weather conditions, but these methods can detect defects only in the upper part of the rail head.

Ultrasonic methods with the excitation of acoustic vibrations using piezoelectric transducers can sound the rail over almost the entire cross section, but require the creation of an acoustic contact by supplying a contacting fluid under the transducers. This circumstance complicates the use of ultrasonic (ultrasound) methods in winter conditions. Therefore, the development of non-contact (without the use of contacting fluid) ultrasonic methods for monitoring rails is relevant.

Of all the known methods for the implementation of non-contact ultrasonic (ultrasound) control of metals (laser excitation and reception of ultrasonic vibrations, control using normal waves over considerable distances, etc.), the most promising and feasible is the use of contactless electromagnetic-acoustic (EMA) transducers, which have a number of significant advantages over the traditional contact method using piezoelectric transducers [1].

Two main structural elements of the EMA converter can be distinguished:

- a magnetizing system consisting of a magnet (a set of magnets or an electromagnet) and a magnetic circuit forming a constant magnetic field;

- an inductor (measuring sensor), usually representing an elliptical (or any other configuration) flat inductor (or several coils) [2].

In the gap between the pole (or concentrator) of the magnet and the controlled product, an inductor coil of an EMA converter is placed, which is a flat coil in the shape of a meander, "butterfly" or another shape. The pulse current of ultrasonic frequency, flowing in a flat coil of the inductor, causes oscillations of the surface layer of the controlled product. Ultrasonic vibrations, propagating through the product, record the desired defects with the echo and / or mirror-shadow methods of ultrasonic inspection.

The efficiency of the EMA conversion directly depends on the magnitude of the magnetizing field created by the magnetizing system of the EMA converter. From [2] it is known that the efficiency of EMA converters in the combined mode (radiation - reception) is proportional to the square of the magnetization field B. In this case, it is sufficient to magnetize only the skin layer of a ferromagnet due to the high-frequency (ultrasonic frequency) electromagnetic field created by the primary EMA converters - inductor coils. It is in the skin layer of a ferromagnet that the mutual conversion of high-frequency electromagnetic and acoustic vibrations occurs. In other words, the efficiency of the EMA conversion depends on the magnetizing system and the magnetic field created by it in the skin layer of the controlled material.

To create large fields with EMA control, magnetizing systems are used, which are massive assemblies of permanent magnets. It was found that the magnetizing field strongly depends on the gap between the magnetizing system and the surface of the controlled ferromagnet [3].

Known EMA converter [4], in which the magnetizing circuit of the magnetizing device is made in the form of a hollow cylinder of magnetic material and, in combination with the "air cushion", ensures a stable position of the inductor coils parallel to the surface of the control object. The design includes through channels connected to the internal channel of the magnetic circuit, which has openings for supplying compressed air at the opposite end. The implementation of the magnetizing device in this form allows you to create an air cushion under the measuring sensor, which partially protects the system from damage if there are irregularities on the surface of the product. A disadvantage of the known device is the design complexity, the need for compressed air and low control sensitivity.

Known EMA transducer [5], which, in order to increase the durability and reliability of the control, is equipped with a tread made in the form of an endless elastic tape and rubberized rollers, and magnetization is carried out using a solenoid placed on the other side of the controlled sheet material mounted with the possibility of rotation relative to axis perpendicular to the surface of the tape. The disadvantage of the known EMAT is the significant design complexity, the presence of contact with the control object, the need for two-way access to the product to accommodate a magnetizing solenoid, and the inability to control the rails.

Known EMA transducer of products and samples of electrically conductive material according to the patent [6], claimed by the German company “Institute dr. Förster GMBH KO”, containing a magnetization unit of the controlled product and a probe (inductor) assembly with inductors located in the field of magnetic field with the possibility of movement relative to the magnetizing node. An advantage of the known device is the implementation of the magnetization unit and the inductor unit (probe unit) with a certain degree of freedom among themselves. In this case, the strong magnetic attraction between the magnetizing assembly and the controlled ferromagnetic product does not affect (or affects very little) the force that presses the inductor assembly to the surface of the product. Due to this, as claimed by the authors of a well-known patent, the control of the ferromagnetic material can be carried out by a small load on the inductor and a low degree of wear while maintaining a sliding contact between the inductor assembly and the surface of the controlled product. A disadvantage of the known device is the use as a magnetization site of a system consisting of permanent magnets (or an electromagnet) located above the inductor at a certain (up to 8 mm) distance. The need to observe this distance leads to the use of a complex design of mutual fastening of nodes and special protective measures to maintain this gap.

Known electromagnetic-acoustic flaw detector for monitoring railroad tracks [7], containing two EMA transducers located at a distance from each other to implement the shadow method of ultrasonic testing. The converters are installed with a clearance relative to the monitored rail and move synchronously along the rail. A disadvantage of the known device is the ability to control only the zone of the rail head and a high level of noise (Barkhausen noise) at significant scanning speeds.

A known method and device for ultrasonic monitoring of rails [8], containing a test wheel with many EMA transducers mounted in specially made recesses in the rim around the perimeter of the test wheel, in the recesses are placed magnetic systems of permanent magnets (in version or electromagnets), a device for holding transducers and inductors. In the process of control, the wheel rolls along the rail and at each moment of time one, two or more EMA converters are in the zone of the contact spot between the wheel and the controlled rail. In this case, the inductor and the permanent magnets located above it are at a minimum distance from the rolling surface of the rail, creating conditions for the excitation / reception of ultrasonic vibrations in a non-contact (dry) way.

The idea proposed in the known method and device for ultrasonic monitoring of rails is very original and, according to the author, allows us to implement ultrasonic monitoring of rails up to 80 km / h in any (including at significant freezing temperatures) conditions without the use of contacting fluid.

The disadvantage of this method and device is the complexity of implementation and low efficiency of excitation / reception of ultrasonic vibrations. The latter is due to the fact that, as is known [2], the efficiency of excitation of ultrasonic vibrations largely depends on the magnitude of the generated magnetic field for magnetizing the controlled sample. The permanent magnets provided in the known device are small in the limited space of the rim of the test wheel and have large scattering fields on the metal structure of the test wheel itself. All this leads to a decrease in the magnitude of the magnetic flux penetrating the controlled rail through the contact patch, and as a result, to the low efficiency of non-contact excitation of ultrasonic vibrations.

The problem solved by the claimed invention is to increase the efficiency of excitation of ultrasonic vibrations in a non-contact (without the use of a contacting liquid) method in a controlled rail at significant scanning speeds while simplifying and improving the reliability of the device design.

The problem is solved in that in a device for electromagnetic-acoustic control of rails containing a test wheel with a plurality of EMA converters evenly placed in specially made recesses in the rim around the perimeter of the test wheel, in accordance with the claimed invention, the magnetic system of the EMA converters is made in the form of a biaxial carts with the placement of solenoids on the axles of the wheelsets, solenoids are connected by a magnetic circuit to the axes of the wheelsets, the wheels serve as poles of an electromagnet and at least one Trolley wheel on each rail is a test yarn, and inductors electromagnetic acoustic transducer sealingly mounted in the wheel rim.

Significant differences and features of the proposed technical solution compared to the prototype are:

1. High efficiency and stability of contactless EMA excitation / reception of ultrasonic vibrations, due to the fact that using solenoids placed on the axles of the wheelsets of a biaxial bogie, as practice shows [9], it is possible to create significant magnetic fields as in the skin layer of the rail surface, and on the section of rails (left and right thread of the track) between the poles of the electromagnet. In the prototype, permanent magnets, the dimensions of which are limited by the size of the rim of the test wheel, cannot create a magnetic flux of sufficient magnitude.

2. Effective use of the magnetic field created by the solenoids for simultaneous control of the right and left threads of the rail track and the creation of a magnetic flux of the required size simultaneously under the 4 wheels of the trolley. In the prototype, permanent magnets mounted in the wheel rim are individual for each high-frequency inductor coil. If we assume, as stated in the prototype, that at least 9 elementary magnets are required for each block of the electromagnetic-acoustic sensor, and up to 500 EMA converters can be placed on the wheel rim, then only for the manufacture of one test wheel 4500 permanent magnets will be required, which greatly complicates increases the cost of construction.

3. The ability, depending on the tasks to be solved, to regulate the magnetic field in the contact spot between the wheel and the rail and in the interwheel section of the rails by adjusting the current in the solenoids of the electromagnets. In the prototype, this possibility is excluded.

4. The simplicity and reliability of the design, due to the fact that in accordance with the claimed technical solution, only flat high-frequency coils — inductors of the EMA converter — must be installed in the wheel rim. In practice, inductors are turns of wire with a thickness of a fraction of millimeters. As a result, in the cross section of the wheel rim, which is simultaneously the supporting wheel of the flaw detector trolley, small (not more than 5 mm) recesses are made to accommodate the inductors, which do not affect the bearing capacity of the wheel. In the prototype, the need to place permanent magnets in the rim of the test wheel forces us to produce complex chambers and protective mechanisms against damage (springs or additional permanent magnets to retract the EMA converters). All this violates the original design of the wheel and reduces its bearing capacity and strength properties.

5. The reliability of the claimed design, which is ensured by the fact that the inductors mounted in the wheel rim are fixed and sealed in the recesses of the rim using a high-strength compound. The prototype provides a movable design of the EMA converters in the chambers (recesses) of the rim. This provides for the presence of a certain technological gap between the EMA unit and the rim design, the pollution of which during operation under real conditions, can lead to a complete failure of the system.

6. The ease of transportation of the device in the idle position, since in the inventive device it is enough to turn off the solenoids on the axles of the wheelsets. In the prototype, the presence of permanent magnets eliminates this possibility.

The inventive device is illustrated by the following graphic materials.

FIG. 1 - Scheme of magnetic flux excitation,

where 1 is a trolley with two wheelsets;

2a and 2b - rail track with rails 2a and 2b;

3 and 4 - wheelsets with wheels 3a and 3b for wheelset 3 and wheels 4a and 4b for pairs 4, respectively;

5 - coils (solenoids) of electromagnets on the axles of wheel sets 3 and 4;

6 - magnetic flux generated by electromagnets on the axles of the wheelsets, closing through the wheels of the trolley and sections of the rails between the wheels of the trolley 1;

7 - the frame of the trolley 1, made of non-magnetic material.

FIG. 2 - Placement of the inductor in the test wheel,

 where 8 is the rolling surface of the test wheel (for example, wheel 3b of the wheelset 3);

9 - inductor - a high-frequency coil located in the recess of the rim of the test wheel;

10 - recess in the rim of the wheel;

11 - high strength compound;

12 - the findings of the inductor 9;

13 - hole in the rim of the wheel;

14 - rolling surface of a controlled rail (for example, rail 2b).

FIG. 3 - Test wheel with many inductors of an EMA converter (for example, wheel 3b of a pair of wheels 3) trolley 1,

where 5 is an electromagnet coil;

9 - inductors of an EMA converter;

14 - hole in the axis of the wheelset;

15 - rail rolling surface (2a or 2b).

FIG. 4 - The formation of ultrasonic vibrations in a controlled rail,

where 9 are the inductors of the EMA converter;

16 - ultrasonic rays directed normally to the rolling surface 15 of rail 2b;

17 - ultrasonic rays in the rail, excited obliquely to the rolling surface 15.

Consider the possibility and implementation features of the claimed device.

Trolley 1 with two wheelsets 3 and 4 (Fig. 1) is mounted on a rail track with rails 2a and 2b. On the axles 3 and 4 of the wheelsets are located solenoids 5 (magnetization coils). Axes 3 and 4 together with coils 5 form a kind of electromagnets. When an electric current is connected to the coils 5, a closed magnetic flux 6 is formed, without air gaps and corresponding losses. The windings of the coils 5 are connected to a voltage source in a coordinated manner so that the magnetic flux 6 passes along the path: axis 3 of the first pair of wheels — wheel 3a — spot of contact between the wheel and rail 2a, rail 2a (one thread of the rail track) — spot of contact of the wheel 4a of the second wheel pairs 4 - axis 4 of another wheelset - another wheel 4b of this pair - rail 2b of another thread of the rail track and wheel 3b of the first pair.

The connecting structural elements 7 of the trolley 1, in order to eliminate magnetic flux losses, are made of non-magnetic material (for example, stainless steel).

The spatial distribution of the magnetic field generated by the proposed magnetizing system is such that, firstly, a high concentration of induction is achieved in the contact area of the wheel rim and the rail. A high level of the magnetizing field (more than 2.0 T) allows efficient emission of transverse acoustic waves provided that the inductors are placed in this region. In addition, a high level of longitudinal magnetization (about 1.0 T) allows the emission of longitudinal acoustic waves into the control object.

A similar magnetization system is used when implementing the magnetodynamic (MD) control method known from patents and publications [10-15]. Successful experience in operating the known magnetization system confirms the feasibility of the proposed technical solution. However, the known technical solutions (MD method) allows you to detect only defects in the rail head, occurring at a depth not exceeding 15 mm from the surface of the rail.

Known technical solutions create a magnetic field on the sections of the rails between the wheels for the implementation of magnetic (magnetodynamic) control and are intended mainly to detect defects in the rail head and transverse kinks in the rails. The system is safe at significant scanning speeds (tested when monitoring rails up to 80 km / h) on operating railways when passing any sections of the track with bolted and welded joints, turnouts, sections of the rail track with level crossings and bridges [10, 15].

Thus, all known considered and similar methods of magnetization have a narrow scope and do not allow to realize non-contact (dry, without using a contacting liquid) excitation and reception of elastic (acoustic) vibrations of ultrasonic frequency and have limited functionality. There are examples of the simultaneous use of MD and ultrasonic methods, when simultaneously with the implementation of the MD method, the ultrasonic control method is also implemented [12, 15, 16]. However, contact ultrasound transducers with all their shortcomings are used (the requirement of the contacting fluid to create an acoustic contact, the instability of the contact during scanning, etc.). The placement of contact ultrasonic transducers in known solutions is associated only with the use of a special trolley with electromagnets on the axles of the wheelsets as a carrier or device for placing contact acoustic blocks when scanning a controlled product.

In order to expand the functionality of the claimed invention, the magnetic flux 6 created by the considered magnetization system is proposed to be used for non-contact (dry, without using a contacting liquid) rail monitoring by EMA excitation / reception of ultrasonic vibrations. To do this, one or two wheels on each rail thread is finalized by installing on the surfaces of the rolling wheels 8 (for example, 3A and 3B), a plurality of inductors 9 EMA Converter. Inductors 9 are installed in the rim of the wheel in the recesses 10 made from the side of the rolling surface 8 of the test wheel.

The recesses are performed by milling or other known methods at equal distances from each other around the entire circumference of the wheel 3A. To exclude the loss of the inductors 9 from the recesses 10, the latter can be performed using known tools, in the form of a connection element of the so-called “dovetail” (Fig. 2). After installing the inductors 9, the recesses 10 are poured with a heavy-duty compound 11 (for example, the high-strength compound Anaterm-206 according to TU 2257-400-00208947-03). The compound can be used under conditions of high pressure, temperature changes and vibration, has adhesion to metals and has chemical and thermal resistance to oil products, gases, solutions of acids and alkalis. When placing the turns of the inductor 9, it is necessary to comply with the condition of the maximum approximation of the turns of the flat coil to the skating surface 8 of the test wheel (and therefore to the skating surface 14 of the controlled rail), while at the same time removing the recesses 10 from the inner wall, which will prevent the occurrence of interfering signals from the wheel rim .

The electrical leads 12 from the coils of the inductor 9 are laid through the drillings 13 in the wheel 3a and the drillings 15 in the axle 3 for subsequent connection through a circular switch with a flaw detector electronic circuit (not shown in the drawing).

When the wheel 3b is mounted on the rail 2b in the area of the contact spot between the rolling surface 8 of the wheel 3b and the rolling surface 14 of the rail 2b, the inductors 9 are sequentially (see Fig. 4). When a probe pulse is applied to the inductors 9 in the current magnetization field 6 (Fig. 1), elastic vibrations arise in the skin layer of the rail, which in the form of ultrasonic waves can sound the controlled product 3b. Depending on the number of inductors in the contact zone and near this zone, normal 16 (perpendicular to the rolling surface 15 of the rail) or inclined 17 ultrasonic vibrations can be excited (Fig. 4).

As the trolley 1 moves along a rail track with rails 2a and 2b from a plurality of inductors 9, several adjacent inductors appear in series in the zone of contact of the wheel with the rail. Moreover, these inductors are briefly located at a minimum distance from the surface 15 of the monitored rail 2a (and 2b), exciting vibrations in the rail. As the wheel rolls, the following groups of inductors 9 are connected to the process of excitation of ultrasonic vibrations sequentially and continuously. Using the known parameters of the test wheel (radius, and hence the circumference of the wheel rim) and the scanning speed, you can determine the instant that any inductor 9 is in the contact area with rail.

In this case, the conditional reference point of the beginning of the wheel circumference can be set in any known manner, for example, using a laser beam and a reflective plate attached to the inside of the test wheel, as proposed in [9]. Knowing the serial numbers of the inductors in the contact zone, you can connect the corresponding inductors to the generator-receiving device of the EMA flaw detector (not shown in the drawing).

The number of inductors 9, evenly placed around the perimeter of the test wheel, is determined by the radius R of the wheel, the maximum realized speed v of the trolley, the minimum conditional length L of the defect to be detected and the minimum number N of echo signals from the defect sufficient for its reliable detection (accept, N > 4).

For example, when monitoring P65-type rails with a height of 180 mm, the travel time of the shear (transverse) ultrasonic vibrations excited by the EMA along the entire height of the rail (to the bottom of the rail and vice versa) is about 110 μs. With a certain margin, let us take the radiation period T of the ultrasonic sounding pulses equal to 140 μs (the frequency of sending pulses is more than 7 kHz (7143 Hz)). With the speed of the trolley v = 72 km / h = 20 m / s and the radius of the test wheel R = 525 mm (the size of a typical railway wheel) for one cycle of radiation / reception of ultrasonic vibrations (equal to period T), the trolley travels only 2.8 mm. In the wheel rim with a circle length C = 2πR = 2 * 3.14 * 525 = 3297 mm, we place 471 inductors every 7 mm of the circle.

When the size of each inductor is 5 × 30 mm [9], ultrasonic vibrations emitted by a specific inductor 9 have time to bounce off the bottom of the rail and return to the same inductor. If you set the minimum conditional size L of the defect required for detection to be at least 50 mm, under the conditions considered above, at least 7 pulses will be received from the desired defect, which is quite sufficient for reliable detection of useful signals against all kinds of interference.

It should be noted that in addition to participation in the process of radiation / reception of ultrasonic vibrations of the oscillators of the inductors 9 that are in direct (through a thin layer of compound 11) contact with the rolling surface 14 of the controlled rail (Fig. 2), nearby are also involved in the formation of ultrasonic vibrations inductors 9, as shown in FIG. 4. Since for them the distance between the inductor and the rail surface (from fractions to several units of millimeters) is still sufficient for the effective excitation of ultrasonic vibrations. Moreover, the larger the diameter of the test wheel, the greater the number of inductors, ceteris paribus, will be at a distance acceptable for the effective excitation of ultrasonic vibrations. This circumstance makes it possible to control the angle of entry of ultrasonic vibrations into a controlled rail (inclined beams 17) in order to form a sequential excitation of a group of inductors by an electronic circuit of a flaw detector (not shown). In this case, radiation at variable or fixed input angles is possible, realizing the so-called phased antenna array (PAR) [1].

The use of the wheel 3b (Fig. 1) as a test is discussed above for an example. Similarly, as the test wheel, the wheel 3a of the trolley 1 on another thread of the track can be made. In the general case, all 4 wheels (3a, 3b, 4a and 4b) of the trolley can be test. It is not necessary to change the magnetization system. The magnetic field generated by the solenoids 5 on the axes 3 and 4 is common and sufficient for all test wheels. This positive property of the proposed technical solution is a significant advantage over the prototype.

The simultaneous use of four test wheels (2 wheels per thread of the rail track) creates new possibilities for processing control signals and contributes to an additional increase in the reliability of rail monitoring.

Thus, the claimed technical solution is realizable, it allows to increase the efficiency of excitation of ultrasonic vibrations in a non-contact way by increasing the magnitude and stability of the magnetizing field with a significant simplification and increase the reliability of the design of the test wheel.

The proposed technical solution can be used to create non-contact high-speed systems of ultrasonic flaw detection of rails, which provide reliable detection of defects in difficult control conditions (with contaminated rolling surfaces, low temperatures, etc.).

Information sources

1. Non-destructive testing: Reference: In 8 t. / Under the total. ed. V.V. Klyueva. T. 6. (p. 40-109 magnetic flaw detection). T. 3. (pp. 72-80 EMA excitation of ultrasound). - M.: Mechanical Engineering, 2008 (T. 3.).

2. Muravyov VV, Strizhak VA, Balobanov E.N. To the calculation of the parameters of the magnetization system of an electromagnetic-acoustic transducer / Measuring equipment, 2011, No. 1 (17), p. 197-205.

3. Gobov Yu.L., Mikhailov A.V., Smorodinsky Ya.G. Magnetizing system for an EMA scanner-flaw detector / Flaw detection, 2014, No. 11, p. 48-56.

4. RF patent 2223487.

5. Patent SU 590660.

6. RF patent 2489713.

7. RF patent 2299430.

8. Patent D 19544217 A1.

9. Antipov A.G., Markov A.A. Assessment of the depth of detection of transverse cracks by the magnetodynamic method in rail inspection / Defectoscopy, 2014, No. 8, p. 57-68.

10. Markov A.A., Antipov A.G. Possibilities of the magnetodynamic method of rail inspection / Control. Diagnostics. 2016, No. 6, from 36-45.

11. Patent RU 10465.

12. Patent RU 2225308.

13. Patent RU 2266225.

14. Patent US 6262573 B1.

15. Markov A.A., Kuznetsova E.K. Defectoscopy of rails. The formation and analysis of signals. Book 2. Explanation of defectograms. - SPb, Ultra Print, 2014 .-- 326 p.

16. Patent RU 2521095.

Claims (1)

A device for electromagnetic-acoustic monitoring of rails, comprising a test wheel with a plurality of electromagnetic-acoustic converters evenly placed in special recesses in the rim around the perimeter of the test wheel, characterized in that the magnetic system of the electromagnetic-acoustic converters is made in the form of a biaxial trolley with the placement of solenoids on the axles of the wheels steam, solenoids are connected by a magnetic circuit with the axles of the wheel pairs, the wheels serve as poles of an electromagnet and at least one wheel of the trolley on Each rail thread is a test one, and the inductors of the electromagnetic-acoustic transducers are sealed in the wheel rim.

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