RU2645818C1 - Method for ultrasonic inspection of rail bases - Google Patents

Abstract

FIELD: test equipment.

SUBSTANCE: use: detection of defects in rail bases. Invention comprises emission of transverse ultrasonic vibrations from the inside with respect to the rail track to the outer spring and the inner spring of the base and receiving reflected ultrasonic vibrations, according to the defectiveness of the rail is judged, introducing ultrasonic vibrations from outside of the base spring at different angles, introducing ultrasonic vibrations from the surface of the rail at an angle of 0 degrees and by two mutually opposite inclined angles along the longitudinal axis of the rail, synchronous moving all electroacoustic transducers along the rail along the scanned surfaces, measuring the traveling path and the current height of the rail, according to specified angles and measured rail height, distance covered along the rail and the distance between the electroacoustic transducers signal divergence is compensated along the length of the rail, the presence of a defect in the rail base is judged by a complex analysis of the signals from all electroacoustic transducers.

EFFECT: technical result: reliable detection of dangerous defects in the rail bases.

1 cl, 3 dwg

Description

The invention relates to the field of non-destructive testing of rails by ultrasonic (ultrasound) method and can be used to detect defects in the sole of rails laid in the path, as well as in repair enterprises of railway transport and the subway.

It is known that the sole of the rails laid in the path is susceptible to corrosion damage, which mainly occurs at the points of contact of the rail with the sleepers. These places are most susceptible to atmospheric effects, chemical and abrasive substances, traction current leaks (electrocorrosion), etc. In places of sole corrosion, fatigue cracks and kinks are possible — defects according to code 69 [1].

In recent years, rail bends on the operated railway lines of Russian Railways are mainly due to defects in the bottom of the rail. In the current 2016, 85% of rail breaks on the road network occurred due to defects in the rail sole. This indicates that the known methods and devices do not provide reliable and timely detection of these defects in the rails.

A known method of ultrasonic control of the sole of the rails, which consists in the fact that they emit an inclined combined transducer into the rail from the skating surface ultrasonic vibrations, receive the reflected ultrasonic vibrations by the same transducer and make a conclusion about the presence and size of the defect by the magnitude of the amplitude and temporary position of the received signals and, accordingly , about quality [2]. But with such a sounding scheme, the reliability of control is small.

A known method of ultrasonic control of the rail sole [3], which consists in the fact that the ultrasonic control of the rail sole is carried out by sounding the control zone with a combined inclined transducer moving along the plane of rolling of the rail, they receive echo signals and register them, while the control area is additionally sounded and receive echoes by a second combined inclined transducer moving along the plane of rolling, and the acoustic axes of both transducers are oriented longitudinally along of the rail axis, but in opposite directions, register the echo signals with the second transducer, shift the defectogram of one of the transducers relative to the defectogram of the other by a distance equal to the distance between the acoustic axes of the transducers in the control zone at the same time, adjusted for the difference in the delay time of the transducers , and the presence of a crack is determined by the temporary coincidence of the echo signals on the offset defectograms.

The disadvantage of this method is the inability to detect defects in the area of the feathers of the sole of the rail, since only defects are found located in the area of the projection of the neck of the rail on the bottom of the rail.

Known methods for searching for defects in the bottom of the rail [4], which consist in the fact that ultrasound transducers directed to the bottom of the rail emit electro-acoustic transducers, receive ultrasound signals reflected from defects by electro-acoustic transducers, repeat these steps by moving the emitters along the rail.

The disadvantage of these methods is the ability to detect defects of significant dimensions in the sole of the rail, and it requires the introduction of ultrasonic vibrations from the edge of the feather pen and the bottom surface of the sole of the rail. As a result, the known methods have low productivity and reliability of control, do not allow to implement the control procedure during continuous scanning.

There is a known [5] method for searching for defects in the rail sole, which consists in transmitting transverse ultrasonic vibrations into the rail, receiving reflected ultrasonic vibrations and measuring their parameters for detecting defects, wherein ultrasonic vibrations emit from the surface of the rail a beam, angle the disclosure of which provides irradiation of the radius transitions from the neck of the rail to the sole reflected from the supporting plane of the sole by ultrasonic vibrations, while the ultrasonic vibrations sequentially re-reflected by the reference plane of the sole, a radius transition from the neck of the rel to the sole, a possible defect in the sole, the edge of the pen of the sole is taken by a group of receiving transducers, including radiating, located along the longitudinal axis of the rail.

This method requires the placement of electro-acoustic transducers - receivers of ultrasonic signals on the edge of the rail feather, which is impossible for operating rails (fastening elements interfere) and with complete monitoring.

A known method of ultrasonic control of the rail sole [6], which consists in the fact that ultrasonic vibrations emit from the surface of the rail beam, the opening angle of which provides irradiation of the radius transitions from the rail neck to the sole reflected from the reference plane of the sole of the ultrasonic vibrations. Ultrasonic vibrations sequentially reflected by the support plane of the sole, a radial transition from the rail neck to the sole, a possible defect in the sole, the edge of the sole of the feather, are received by a group of receiving transducers, including radiating, located along the longitudinal axis of the rail.

An experimental verification of the known method shows that it is really possible to “pump” ultrasonic vibrations into the sole feathers, however, the reflected signals from potential defects in the sole feathers have unacceptably low amplitudes and in most cases turn out to be lower than the noise level. As a result, the known method has a low noise immunity and reliability control.

Closest to the claimed method is a method of ultrasonic testing of the sole of railway rails [7], which consists in the fact that three combined ultrasonic transducers are installed on the inner plane (relative to the track) of the feather of the rail sole, directing the radiation axis according to the scheme: one transducer to the edge of the inner pen, two transducers working in tandem to the edge of the outer pen. The ultrasound input points of the three ultrasonic transducers are located on the inner recess of the rail sole at a predetermined distance from the rail axis of symmetry. Transverse ultrasonic waves emit transducers into the rail, receive ultrasonic waves reflected by the defect at the same point, measure the parameters of the received vibrations and determine the quality of the rail from them.

As you can see, the main attention in the implementation of the known method is paid to the edge of the outer rail feather and little attention is paid to the central part (in the projection of the rail neck) and the inner edge of the rail sole. In real conditions, rails with lateral wear of the head are removed from the main tracks and shifted with a change of edge to less loaded sections of the track. Therefore, defects can appear both from the side of the load in the current period (in the prototype, the inner side of the track), and from the outside. In addition, defects in the feathers of the sole may appear due to stresses caused on the curved sections of the path. Naturally, the curves can be in one or the other side of the path plan. Another, very common reason for the appearance of cracks in the feathers of the sole is the so-called “arson” caused by the non-optimal passage of the welding current from the sponges of the welding machine on rail welding machines both in stationary conditions (CPF) and in transit (PRSM). Therefore, in the diagnosis it is necessary to pay equal attention to both sides of the feathers and the center of the sole. The disadvantage of this method, adopted as a prototype is the low reliability of detection of defects in the sole of the rails.

The problem solved by the claimed method is the reliable detection of damage to the sole of the rail, taking into account the actual operating conditions of the rails.

The problem is solved due to the fact that in the method of ultrasonic inspection of the rail sole, which consists in the fact that transverse ultrasonic vibrations are emitted from the inner side relative to the track of the rails into the outer feather and the inner feather of the rail sole, and the reflected ultrasonic vibrations are received, from which the rail is defective additionally enter ultrasonic vibrations and from the outside of the sole feather at different angles, provide ultrasonic vibrations from the rolling surface of the rail at an angle of 0 degrees and two I mutually opposite oblique angles along the longitudinal axis of the rail, synchronously move all electro-acoustic transducers (EAF) along the rail along the scanned surfaces, measure the travel path and current height of the rail, using the given angles and the measured height of the rail, the distance traveled along the rail and the distance between the EAF carry out compensation discrepancies of signals along the length of the rail, the presence of a defect in the sole of the rail is judged by a joint analysis of signals from all EAPs.

Significant differences of the proposed method in comparison with the prototype are:

1. Sounding of the entire section of the rail sole using inclined EAFs located on the upper planes, internal and external, of the feathers of the sole of the rails and the joint work of these EAAs. For example, an EAA placed on the inner sole of the sole emits ultrasonic vibrations, and ultrasound images mirrored from the plane of a transverse crack of an ultrasound wave are received by an EAA placed on the outer sole of the sole (and vice versa).

In the prototype EAP are placed only on the inner pen, and, of course, the implementation of such a (mirror) scoring scheme is not possible.

2. To detect defects in the sole of the rails, inclined EAFs are used, placed both on the feathers of the sole and on the tread surface of the controlled rail. Moreover, there is a full-fledged sounding of the central part of the sole of both the EAA, placed on the feathers of the sole, and the EAA, placed on the rolling surface of the rail head. This is especially important because, according to statistics (see pages 246-250 [8]), more than half of the fractures due to defects in the sole of the rails are caused by transverse cracks in the sole, located in the projection of the neck, accessible to scoring and from the surface of the rail.

In the prototype, little attention is paid to the detection of transverse cracks in the Central part of the sole of the rail, which reduces the reliability of the control in a known manner.

3. Measurement of the current rail height using a direct EAF allows you to very accurately calculate the expected temporal positions of echo signals from transverse cracks and perform a correct comparison of signals received by different EAAs, which, in comparison with the prototype and well-known analogues, increases the reliability of the rail sole control. Measurement of the rail height is very important, since the allowable wear of the rails in height reaches up to 10 mm, which changes the path of the path of ultrasonic vibrations in the process of sounding the sole defect from the rolling surface by more than 30 mm.

In the prototype, such measurements are not provided.

4. Measure the path of the EAP during the scanning process by known methods, for example, an encoder, which allows you to determine the time delay of the signals received by different EAP relative to the detected defect.

In the prototype, measurements of the EAP distance traveled during the scanning process are not claimed.

5. Compensate for the discrepancy of the signals along the rail length according to the measured values of the current rail height, the paths of the EAP system movement (according to paragraphs 4. and 5 of this list of differences), as well as the given angles for introducing ultrasonic vibrations of all EAPs and the mutual distances between them. Combining the measurement results obtained from all electro-acoustic transducers, so that they belong to the same cross-section of the rail, allows you to get a more detailed picture of the state of the bottom of the rail. Defects in the sole of the rails are unpredictable in shape, depth, and other parameters, as a result of which the reflections of the ultrasonic sounding signals are random in nature. In these conditions, the use of information from all electro-acoustic transducers is useful. Making a decision on a defect of the sole of the rail on the basis of joint processing of the results allows to increase their reliability.

In the prototype, such compensation is not stated, which reduces the reliability of detection of defects in the sole of the rails.

The inventive method is illustrated by the following graphic materials:

FIG. 1 - schematic diagrams of the installation of an EAP on rail surfaces, where: 1 - rail;

2, 3 and 4 — rail surfaces from which ultrasonic vibrations are input and received: 2 and 3 — upper planes of the inner and outer (relative to the track of the rails) feathers of the sole; 4 - rolling surface of the rail head, respectively;

5 - inclined electro-acoustic transducers emitting transverse ultrasonic waves;

6 - electro-acoustic transducer directed orthogonally (at an angle of 0 degrees) to the rolling surface of the rail and emitting longitudinal ultrasonic waves;

7 - trajectories of the axes of the radiation pattern of ultrasonic rays of transverse vibrations;

8 - trajectories of the axes of the radiation pattern of ultrasonic rays of longitudinal vibrations;

9 - defects, transverse cracks in the feathers of the sole of the rail;

10 - defects, transverse cracks in the Central part of the bottom of the rail.

FIG. 2 is a schematic diagram of the installation of an EAA on the feathers of a rail sole (only the lower part of the rail is shown below section AA in FIG. 1), where the symbols of the elements correspond to the symbols in FIG. one.

FIG. 3 is a schematic diagram of the installation of an EAA on a rail surface, where the designations of the elements correspond to the designations of FIG. 1 and 2:

5 - inclined electro-acoustic transducers emitting transverse ultrasonic waves at the input angles α _n and α _о (n - “running over” and о - “moving away” EAP;

6 - electro-acoustic transducer directed orthogonally to the rolling surface of the rail and emitting longitudinal ultrasonic waves;

B - the base distance between the inclined EAA 5 located on the rolling surface 4 of rail 1; H - rail height 1.

The method of ultrasound control of the sole of the rails is as follows.

Electro-acoustic transducers (EAP) 5, emitting ultrasonic vibrations at an acute angle to the scanning surface, and EAP 6 emitting ultrasonic vibrations normally (orthogonally) to the input surface are installed on the scanned surfaces 2 and 3 of the sole feathers and the rolling surface 4 of the rail 1 head. In order to preserve the initial positions of the EAA, when implementing the method, it is advisable to combine individual EAA groups into acoustic blocks, as shown in FIG. 2 and 3 (2 blocks on opposite feathers of the sole and one block on the ski surface).

The frequency of the emitted ultrasonic vibrations and the angles of entry of the inclined EAF during the implementation of the method satisfy the requirements of GOST [9] and regulatory documents of Russian Railways [10] with manual control of the rail sole.

All EAFs 5 and 6 are synchronously moved along the scanned surfaces of rail 1 using a specialized device (not included in the application) with a displacement sensor (not shown in Fig.) And all signals received by the echo and mirror methods of ultrasonic testing are recorded [9].

Using EAP 6, the current height H of rail 1 is determined in a known manner (from the measured time interval between the probe pulse and the bottom signal (from the bottom of the rail) and the known propagation velocity of the longitudinal ultrasonic wave in the rail with ₁ = 5900 m / s).

Observation, registration and joint processing of the received signals is carried out using a digital multi-channel flaw detector with an integrated processor (not shown in Fig.).

In order to increase the reliability and probability of detecting various defects in the bottom of the rails in the proposed method, the most dangerous (from the point of view of the appearance of defects) sounding from different directions is performed.

For example, a transverse crack in the central part of the sole of the rail (defect code 69 according to [1]), developing from the bottom plane of the sole, can be voiced by the inclined EAF 5 along the paths 7 from the outer and inner feathers of the sole (Fig. 2) and echo and mirror ultrasound control methods as a colliding pair of EAPs, and departing; inclined EAA 5 from the rolling surface 4 (Fig. 3) of the rail head 1 - by the echo method, along the path 7. Moreover, in the latter case, as practice shows, due to the formation of an angular reflector between the sole plane and the crack, defects of very small sizes are confidently detected (height from 5 mm).

Cross cracks in the feathers of the sole are also voiced by several EAPs with the arrival of ultrasound waves from different directions. For example, the upper right side of the sheet in FIG. 2, a transverse crack in the sole of the soles (we will conditionally assume that on the inside of the track) is voiced at least 4 times: by the incoming and outgoing EAP 5 from the opposite outer pen and also by the differently directed EAP 5 from the inner side of the pen (Fig. 2).

In order to avoid narrowing the subject of the invention, specific angles of entry of inclined EAPs are not indicated in the claims. In the process of experimental studies, the authors used the input angles α _n and α _about equal to 45 ° when introducing ultrasonic vibrations from the rolling surface of the rail and 70 ° when entering from the upper surfaces of the feathers. In the general case (for example, when monitoring rails of foreign manufacture such as UIC 60 and others, which differ in configuration from domestic ones), it is possible to use other input angles that ensure reliable identification of the desired defects.

The need to duplicate the sounding of potential defects in order to increase the reliability of the control is explained by the fact that signals can be received not only from transverse cracks, which are the most dangerous defects, but also from mechanical damage to the sole, which at this time does not pose a danger. Often, defects that occur on the surface of the rail sole from friction of the lining are fixed, and a signal can be recorded from the diffusely reflecting surface. Moreover, in a known manner it is impossible to distinguish a corrosion shell from a crack.

It is the synchronous movement of all EAFs, compensation for discrepancies from the same defect along the length of the rail by registering the scanning path and converting the signals into a single section, as well as the combined processing of the signals by the claimed method and it is possible to reliably identify dangerous transverse cracks in the bottom of the rails against the background of all kinds of interference. Joint processing of the signals is carried out taking into account the measured current values of the height H of the rail 1, the basic distances between all the EAFs (Fig. 3 shows, as an example, the distance B between the two inclined EAFs 5), the paths of the EAF moving in the process of sounding defects, knowledge of the propagation speeds of ultrasound oscillations in the metal of the rail (for EAA 6 - with ₁ = 5900 m / s, for EAA 5 - with _t = 3260 v / s) in the processing unit of the flaw detector processor (not shown in Fig.) or in a separate processing unit with obvious algorithms for the above data.

Thus, the inventive method can be implemented and provides the ability to reliably detect dangerous defects in the sole of the rail.

An important feature of the proposed method is that traditional ultrasonic multichannel flaw detectors [2] with sounding schemes proposed in the method can be used for its application and requires only changes in the processing algorithms of the results and the introduction of additional scanners on the feathers of the sole.

Information sources

1. Instruction “Rail defects. Classification, catalog and parameters of defective and acute defective rails. " Approved Russian Railways by order No. 2499r of 10.23.2014. - 140 p.

2. Markov A.A., Shpagin D.A. Ultrasonic flaw detection of rails. 2nd edition, revised. and add. St. Petersburg: Education-Culture, 2013.284 s.

3. Patent RU 2436080.

4. Patent US 4593569.

5. G. Garcia, D. Davis, Railway Track & Stuctures, 2002, No. 8, p. 18-21.

6. Patent RU 2353924.

7. Patent RU 2085936.

8. Markov A.A., Kuznetsova E.A. Defectoscopy of rails. The formation and analysis of signals. Book 1. Basics. A practical guide in two books, edited by Doctor of Technical Sciences A.A. Markov. SPb .: KultInformPress, 2010 .-- 292 p. (see pages 246-250).

9. GOST 18576-96. Non-destructive testing. Rails are railway. Ultrasonic methods. - Minsk, 1996.

10. Regulation on the system of non-destructive testing of rails and the operation of means of rail defectoscopy in the track facilities of railways of JSC Russian Railways. - Rasp. Russian Railways OJSC No. 2714r of December 27, 2012.

Claims (1)

The method of ultrasonic inspection of the rail sole, which consists in the fact that transverse ultrasonic vibrations are emitted from the inner side relative to the track of the rails into the outer feather and the inner feather of the rail sole and receive reflected ultrasonic vibrations, which are used to judge the defectiveness of the rail, characterized in that ultrasonic vibrations are inputted and from the outside of the pen of the sole at different angles, provide input of ultrasonic vibrations from the rolling surface of the rail at an angle of 0 degrees and two mutually opposed the inclined angles along the longitudinal axis of the rail, synchronously move all the electro-acoustic transducers along the rail along the scanned surfaces, measure the travel path and the current rail height, using the given angles and the measured rail height, the distance traveled along the rail and the distance between the electro-acoustic transducers, compensate for the difference in signal length rail, the presence of a defect in the sole of the rail is judged by a joint analysis of signals from all electro-acoustic transducers.

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