RU2753810C1 - Method for evaluating the performance of flaw detection equipment during high-speed inspection of rails - Google Patents

Abstract

FIELD: flaw detection equipment performance evaluation.

SUBSTANCE: invention relates to performance evaluation of flaw detection equipment during high-speed inspection of rails. The substance of the invention lies in the fact that the flaw detection equipment is moved along the rail, periodically emitting ultrasonic sounding signals into the controlled rail, receiving the reflected ultrasonic signals from the structural elements of the rails and registering them, measuring the signal parameters and analyzing them, the results of which are used to judge the performance of the flaw detection equipment, while the performance is evaluated at different speeds of movement of the flaw detection equipment, a nomogram of the dependence of the average estimate on the speed of movement is formed, according to which the maximum control speed for a specific section of the rail track is determined.

EFFECT: invention improves the quality of evaluation the performance of flaw detection equipment at high scanning speeds.

2 cl, 3 dwg

Description

The method for assessing the performance of flaw detection equipment during high-speed inspection of rails belongs to the field of non-destructive testing of railways and can be used to test the performance of mobile flaw detection equipment. The method can be applied both in the introduction of new high-speed flaw detection tools and in the periodic assessment of the operability of the operated flaw detection tools and diagnostic systems on specific sections of the rail track.

The special (test) track sections available on a number of railways with models of various rail defects, intended for tuning and checking the performance of the equipment of the previous generation flaw detector cars, have limited (short) lengths and rarely make it possible to achieve inspection speeds above 30-35 km / h. [1].

A known method of testing the operability of mobile flaw detection means [2] consists in the fact that the tool is moved along the test section of the rail track with artificial defects of various configurations. In the process of movement of the device, signals from artificial defects are recorded and, according to their parameters, the operability of the mobile device is judged.

The disadvantages of the methods [1 and 2] for testing the performance of flaw detection tools on specially created test sections of the track are the limited scope and low quality of performance testing.

The limited scope is associated with the need to create and maintain special (test) track sections with defect models on the railways. To check the performance of the defectoscopy means, it is necessary to interrupt the scheduled inspection of the rail track and organize a special drive to the test section. It is obvious that the test site can be located at a considerable distance from the place of scheduled control. In addition, a significant limitation of scanning speeds at test sites (up to 30-60 km / h) does not allow testing the performance of the equipment in high-speed operating modes.

The low quality of testing the performance of flaw detection equipment is associated with different scanning conditions caused by significant differences in the condition of the rails on the existing tracks and in lightly loaded test sections. In the test section, the unrolled rail surface. On existing track sections, the rolling surface of the rails, as a rule, is polished by the wheels of trains, which contributes to better acoustic contact between the rail and the electroacoustic transducer (EAC).

During the implementation and operation of high-speed diagnostic systems equipped, among other things, with ultrasonic (US) equipment for rail flaw detection, it is very important to evaluate and periodically check the performance of flaw detection equipment in the entire range of operating speeds (from 0 to 140 km / h). Naturally, in such a wide range, the control conditions change significantly. The quality of the acoustic contact, the number and amplitude of pulses received from a defect of the same type change. At high speeds, compression of the location zone (conditional length) of the defect occurs due to a noticeable EAP shift during the propagation of ultrasound signals to the defect and back [3, 4, 5]. Therefore, a full-fledged and high-quality test of the performance of ultrasonic flaw detection equipment can be carried out only at operating scanning speeds.

Creation of a special test track section for high speeds (up to 140 km / h) is a very expensive project and not always technically justified, because the rolling surface and the very condition of the rails on active tracks and on lightly loaded test sections (which are usually located on lateral tracks) are noticeably different.

There is a known method for assessing the performance and adjusting the sensitivity of a rail ultrasonic flaw detector [6], which consists in the fact that the flaw detector is emitted into the controlled rail and received from structural elements in it ultrasonic signals, the amplitude of the ultrasonic signal received from the known reflector is estimated, according to which the sensitivity of the flaw detector is adjusted. A distinctive feature of the known method, taken as a prototype, is the use of structural elements of rails as test reflectors for testing the performance of a flaw detector: bolt holes, ends of rails. This allows you to check the operability and adjust the sensitivity of the control directly during the working passage on the tested rails and does not require the use of special test track sections.

The disadvantage of this method is the limited scope and low quality of testing the performance of the ultrasonic flaw detector at high scanning speeds.

The problem solved by the claimed method is to improve the quality of testing the performance of flaw detection equipment at high scanning speeds in order to increase the reliability of the control of rails.

To solve the problem posed in a method for assessing the performance of flaw detection tools during high-speed inspection of rails, which consists in moving the tool along the rail tracks, in periodic radiation into the controlled rail of ultrasonic sounding signals, receiving reflected ultrasonic signals from the structural elements of the rails and registering them, measuring the parameters of signals and their analysis, according to the results of which the operability of the defectoscopic device is judged, moreover, the operability is assessed at different speeds of movement of the defectoscopic tool, a nomogram of the dependence of the averaged estimate on the speed of movement is formed, according to which the maximum control speed for a specific section of the rail track is determined.

Moreover, in a particular case, integral indicators of signals from structural elements are used as an average estimate.

In another special case, typical holes of bolted joints of rails are used as structural elements, with the exception of holes closest to the joint.

Hereinafter, the operability of a defectoscopic tool is understood as the state of the tool, in which it is capable of performing its functions of detecting defects in rails with certain parameters in a given range of travel speeds along the rail track. The ability to detect defects by means, according to the claimed method, is evaluated indirectly by using the integral indicator of signals from structural elements averaged in each speed range. In a particular case, typical holes of bolted joints are used as structural elements, with the exception of holes closest to the joint.

The technical result is an increase in the reliability of the control of the rails due to the periodic check of the operability of the flaw detection means without the use of special test track sections and a reasonable choice of the maximum scanning speed for different sections of the rail track.

Significant differences of the proposed method in comparison with the prototype are as follows.

An averaged assessment of the operability is carried out at different speeds of movement of the defectoscopic device, which makes it possible to assess the detectability of internal reflectors with specified parameters in the entire range of speeds of monitoring the track. In the prototype, the issues of assessing the performance of the tool at different speeds are not considered.

A nomogram of the dependence of the values of the averaged estimate on the speed of movement of the defectoscopic means is formed, which makes it possible to objectively determine the working range of inspection speeds for the controlled section of the rail track. In the known methods for assessing the performance of a defectoscopic device, such a relationship is not used.

To obtain an average estimate, integral indicators of signals from structural elements are used. The integral indicator makes it possible not only to fix the number of received signals from structural elements, but to evaluate the quality of the received signals, taking into account the amplitude of all echo pulses and the conditional length of each group (pack) of signals received from the sought reflector as the rails are scanned through all channels of the flaw detector. The prototype uses the amplitude characteristics of the echo signals received, mainly, by one flaw detection channel from one or more structural elements, which does not allow correctly assessing the flaw detector's performance.

In the particular case of the implementation of the proposed method, typical holes of bolted rail joints are used as structural elements, with the exception of the holes closest to the joint. The exclusion of signals from the first (closest to the joint) bolt holes for assessing the performance of the flaw detector is due to the fact that these reflectors are not fully sounded due to extremely unfavorable conditions, since It is the end (end-end) sections of the rails that experience the maximum dynamic effect from the wheels of passing trains, often have a damaged rolling surface and are of little use for ultrasonic control [7]. In the prototype, this factor is not taken into account, which leads to a decrease in the reliability of the results obtained.

The inventive method is illustrated by the following graphic materials.

FIG. 1. Scheme of rail sounding by inclined and straight EAT, where:

1. Controlled rail (fragment).

2. Bolt hole.

3 and 4. Inclined EAT, respectively, approaching (3) and departing (4) to the defect (to the reflector in the form of a bolt hole 2).

5. Direct EAT with ultrasonic vibration input angle 0 ° (normal) to the scanning surface.

6 and 7 in FIG. 1. Defectograms in the form of a type B scan, respectively, for oblique (6) and straight (7) EAT.

8 and 9. Groups (bursts) of signals received by oblique EAT on a type B scan.

10 and 11. Bottom and echo signals received by the direct EAT.

FIG. 2. Nomogram for determining the limiting (permissible) speed of inspection for flaw detection equipment A and B, where:

K _av and K _thr are the averaged estimate of the signals from the structural elements of the rails and its threshold value, respectively.

V _tech and V _lim are the maximum control speed of the diagnostic tool indicated in the passport and the maximum control speed for the section of the path (the case is shown for diagnostic tool B), respectively.

ΔV is the required sub-range of control speeds.

FIG. 3. Algorithm (simplified) for the implementation of the proposed method during the test (first) and subsequent (through the planned time interval T _plan ) control of the track.

Consider the possibility of implementing the proposed method.

A high-speed flaw detector (flaw detector car or diagnostic complex) moves along the rail tracks at speeds V from zero to the passport value of the speed of this device V _tech .

Several EAP are installed in the search system and from the rolling surface of the rails 1 emit ultrasonic sounding pulses into the metal of the rails. Transducers based on piezoelectric plates with contact input of ultrasonic vibrations or contactless electromagnetic-acoustic (EMA) transducers can be used as EAP 3-5.

If there are internal reflectors in the rails, the echo signals from them are received and recorded by a flaw detector. Based on the results of measuring the parameters of echo signals and their analysis, the performance of the flaw detector is judged.

Due to the influence of various factors during high-speed control of rails, the parameters of ultrasonic echo signals from the same reflector undergo significant changes. These factors include: limited frequency of sending probing pulses; instability of acoustic contact; noticeable displacements of the search system with the EAT during the travel of ultrasonic vibrations to the reflector and back, etc.

In addition, the condition of the rail track significantly affects the quality of performance of flaw detection equipment at high speeds. Naturally, in sections of high-speed passenger traffic, the state of the rail surface is favorable for contact or non-contact injection of ultrasound into the metal. In especially heavy traffic areas - the presence of surface damage on the rails, wear of the rolling surface, vertical steps at the rail joints, etc. - degrades the quality of the defectoscopic equipment. Therefore, in high-traffic areas, high-speed flaw detection equipment may not provide the declared passport speeds of ultrasonic control up to 120 ... 140 km / h.

In accordance with the claimed method, it is proposed to preliminarily, during the first (test) drive, evaluate the performance of the defectoscopic device and determine the maximum allowable (limiting) control speed on a specific section of the track.

The influence of high testing speeds on the characteristics of signals from defects in rails is expedient to be carried out using echo signals from typical reflectors with known parameters recorded on real defectograms. For the analysis, it is necessary to select reflectors of the same type in sufficient quantity for statistical analysis, which have identical parameters.

In the particular case of the implementation of the proposed method, as such reflectors it is proposed to use the holes of the bolted joints of rails with a diameter of 36 mm (for rails of the P65 type), made in accordance with GOST [8]. Despite the massive transition to a continuous welded track, there are sufficient numbers of bolt holes on the existing tracks in the zone of discharge (equalizing) links and in places of temporary restoration of rail strings. In addition, there are still many sections of the link track left on the railways.

Sounding schemes of modern high-speed cars-flaw detectors and diagnostic complexes provide sounding of bolt holes 2 (used as test reflectors) by at least three EAT (Fig. 1):

- two differently oriented inclined EAPs 3 and 4;

- direct EAP 5.

Registration of control signals is performed on a defectogram with display of signals on a type B scan separately for oblique (6) and straight (7) channels. At the same time, on the B-scan, groups (packs) of signals are formed from the approaching inclined EAT 3 (pack 8) and from the departing EAT 4 (pack 9). The direct EAT 5 on the B-scan forms the line of the bottom signal 10. When the EAT 5 is above the reflector (bolt hole), the line of the bottom signal 10 is interrupted and a horizontal burst of echo signals 11 is formed [9].

Shown in FIG. 1, the bursts of signals 8, 9 and 11 carry information about the number of received echo pulses, the time position of each echo signal relative to the probe pulse and their conditional length along the rail length (ΔL _inc , ΔL _str ).

In modern high-speed monitoring tools, there is an additional possibility of evaluating the amplitude of each received from the reflectors echo pulse (not shown in Fig. 1).

In the known methods for evaluating reflectors, as a rule, any one of the parameters of the ultrasonic signals (the number of pulses in the burst, the conventional length of the burst, the maximum amplitude of the echo signal, etc.) is used.

In the claimed method, for a more complete assessment of the received signals, a generalizing (integral) indicator of signals [10] from bolt holes is used, taking into account multichannel control.

The integral indicator makes it possible not only to fix the number of signals from the reflectors, but to evaluate the quality of the received signals, taking into account the amplitude of all echo pulses and the conditional length of each burst, received from the sought reflector simultaneously through all channels of the flaw detector [11].

In general, modern diagnostic tools, in addition to ultrasonic channels, can implement other non-destructive testing methods (magnetic, visual, eddy current, etc.). When calculating the integral indicator, it is possible to take into account the parameters of signals from the listed methods, thereby further improving the quality of assessing the performance of flaw detection equipment in a wide range of testing speeds.

The integral indicator K _int is a linear combination of individual indicators K _n , n = 1, ..., M, in M flaw detection channels of the complex that recorded signals from a defect (in Fig. 1 M = 3):

where 0≤ a _n ≤1 is the weighting factor of the channel n

The K _n index in a separate channel is determined by the expression:

where N is the number of received echo pulses in the pack (in one channel), U _i is the amplitude of the ith echo signal in the pack, l is the scanning step along the rail length, m _n is the maximum possible signal from the reflector for normalizing the K _{n index} (0≤K _n ≤1).

The integral index of test holes is calculated and recorded automatically in the program for displaying the recorded defectograms.

During the test drive, the speed of the diagnostic tool must be increased gradually from zero to the passport value V _tech (for example, up to 120 km / h). In this case, the flaw detector must have time to fix a sufficient number of bolt holes for subsequent analysis.

To simplify the analysis procedure in the claimed method, it is proposed to divide the entire range of scanning speeds into subranges of ΔV. For example, when the speed is set from 0 to 120 km / h, 12 sub-ranges of 10 km / h can be selected. Naturally, depending on the desired accuracy of determining the permissible control speed, these ranges can be divided into smaller values (for example, 5 km / h).

In each selected sub-range of speeds, an averaged (average) estimate of the performance of a defectoscopy tool is determined by the expression:

where K _i is the integral index of the i-th bolt hole, i is the number of fixed holes.

Based on the obtained values of K _{av, a} nomogram of the dependence of the averaged performance assessment on the control speed is constructed (Fig. 2). On the same nomogram, the line of the threshold value of the averaged estimate K _thr , admissible for a given section, is plotted.

For example, for sections of the route with predominantly freight traffic, the threshold level K _thr can be selected at the level of 0.7 relative to the maximum value (1.0) of the K _av indicator obtained at low speeds. On passenger lines, the K _thr level can be 0.9 of the maximum value.

In the particular case of the implementation of the method, when choosing bolt holes as typical reflectors, signals from the second and third holes in the abutting rails (if counted from the joint) should be selected, with the exception of the holes closest to the ends. It is known that the edge sections of abutting rails operate in difficult conditions, where there are most often surface damage, drooping ends, vertical steps, etc. As a result, the first (closest to the ends) bolt holes cannot be fully inspected.

The exclusion of the holes closest to the joint from the calculation of the integral indicators K _i and the averaged estimate K _{av of the} defectoscopic device operability makes it possible to obtain more correct data for the main part of the rail track.

At the point of intersection of K _av with the threshold level K _thr , the limit speed V _{lim of the} control for the section of the path is determined (in Fig. 2 for means B).

Perhaps, due to a better design of the search system and more optimal signal processing, the K _av curve for means A (Fig. 2) may not intersect at all with the threshold level or have a different, higher V _lim value. In this case, the control of this section can be carried out up to the maximum speed corresponding to the passport value for this V _tech facility.

The sequence of the implementation of the proposed method in the process of the first (test) passage and subsequent regular checks of the rail track (through T _plan ) can be followed by the algorithm in Fig. 3.

The first steps of the algorithm are obvious. After plotting the nomogram, the K _av curve is compared with the threshold level K _thr .

If the average estimate K _{av is} lower than K _thr , then the limiting control speed for this section of the path V _lim is fixed. After the planned period, the main check of the track is performed with an operating speed not exceeding V _lim . If the K _av indicator does not fall below K _thr , it is possible to control the section at a speed corresponding to the passport value for this V _tech facility.

Depending on the state of the track, as noted above, the same flaw detector during high-speed testing can have a different limiting speed of testing V _lim . Obviously, on sections of the track with poor maintenance, this speed is lower than on sections with good maintenance. FIG. 2, the flaw detector B ensures the performance of functions for detecting defects in rails with certain parameters in the speed range from 0 to V _lim . And flaw detector A can provide effective operability in the range of speeds from 0 to V _tech , providing the required reliability (the average estimate of the speed is above the K _thr threshold).

Test drives to assess the performance of a flaw detection device in accordance with [1] should be carried out at least once every six months, because within a specified period of time, there may be a change in individual technical characteristics of the vehicle or the operational properties of the rails on monitored (for example, on especially heavy traffic) track sections.

Even during the first (test) drive, the flaw detection system provides detection of defects in the rails. It is possible that at significant control speeds (close to the passport speed V _tech ), the performance of the facility will be low, and the site control will be performed inadequately. But already with the next planned passages, not allowing the control speed to exceed the V _lim value, the required control efficiency of the track section will be ensured.

Thus, the use of a set of distinctive features of the proposed method:

- assessment of the performance of the tool at different speeds of movement V;

- using typical rail bolt holes as reference reflectors;

- the use of integral indicators of reference reflectors to form an averaged estimate of K _av ;

- determination of the limiting control speed V _lim according to the nomogram;

allows to obtain the claimed technical result - increasing the reliability of the control of rails at high speeds due to periodic testing of the performance of flaw detection equipment.

Not only bolt holes, but also other structural elements in rails, for example, rail ends in bolted joints, elements of turnouts, holes in the zone of aluminothermic welded joints, etc., can be used as reference reflectors used to test the operability of diagnostic tools.

The main advantage of the proposed method is that the assessment of the performance of defectoscopic means during high-speed control of the rail track is carried out without the use of special expensive test track sections with models of defects, but, directly, in the process of working control of the operated rail track.

Thus, the inventive method can be implemented and ensures the reliability of the detection of defects in the rails at high scanning speeds.

Sources of

1. Instructions for checking the performance of non-destructive testing equipment of rails on test track sections TI 07.139-2020 (approved by JSC Russian Railways No. 1771 / r dated 19.08.2020).

2. RU 134133.

3. RU 1035506.

4. RU 1429013.

5. Markov A.A. Peculiarities of evaluating the conditional sizes of defects at significant scanning speeds. Defektoskopiya, 1988, No. 3. S. 8-11.

6. RU 2603332.

7. Markov A.A., Garaeva B.C. On acoustic contact in the zone of bolted joints // Way and track facilities. 2008, no.12. 15-17.

8. GOST R 51685 - 2013. Railway rails. General technical conditions.

9. Markov A.A., Kuznetsova E.A. Flaw detection of rails. Formation and analysis of signals. Book 2. Decoding of defectograms. St. Petersburg: Ultra Print. 2014.325 s.

10. RU 2699942.

11. Markov A.A., Maksimova E.A., Antipov A.G. Analysis of the development of rail defects based on the results of multichannel periodic inspection // Defektoskopiya. 2019. No. 12. S. 3-15.

Claims (3)

1. A method for assessing the performance of defectoscopic devices during high-speed inspection of rails, which consists in moving the tool along rail tracks, periodically emitting ultrasonic sounding signals into the controlled rail, receiving reflected ultrasonic signals from structural elements of the rails and registering them, measuring signal parameters and analyzing them, according to the results which is judged on the performance of the defectoscopic device, characterized in that the performance is assessed at different speeds of movement of the defectoscopic device, a nomogram of the dependence of the averaged assessment on the speed of movement is formed, according to which the maximum control speed for a specific section of the rail track is determined. 2. A method for assessing the performance of defectoscopic devices during high-speed inspection of rails according to claim 1, characterized in that integral indicators of signals from structural elements are used as an averaged estimate. 3. A method for assessing the performance of flaw detection means during high-speed inspection of rails according to claim 1, characterized in that standard holes of bolted joints of rails are used as structural elements, with the exception of holes closest to the joint.

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