RU2800214C1 - Method for automatic monitoring of the state of rail bars of a railway track - Google Patents

Abstract

FIELD: testing.

SUBSTANCE: invention relates to methods of non-destructive testing of materials by studying stray magnetic fields and can be used in monitoring seamless rail bars in order to prevent path stability violations under the influence of longitudinal temperature forces. The method for automatic monitoring of the state of the rail bars of a railway track consists in placing sets of marks made of ferromagnetic materials at predetermined places on the track, one of the marks of the set being placed on a reference sleeper, the second at a known distance from the first on the rail head. Marks are detected by a flaw detection tool that periodically monitors rail tracks equipped with a magnetization system and magnetically sensitive sensors, the displacement of the rail bar is estimated by comparing the current distance between pairs of marks with the results of previous measurements and with acceptable values. According to the signals of the magnetically sensitive sensor, caused by the scattering of the magnetic field in the area of the butt gap, the bolted joints of the rail track are detected. The amplitude and spatial characteristics of these signals determine the magnitude of the butt gaps. According to the joint analysis of the values of the butt gaps and displacements of the rail bars relative to the reference marks, the state of the rail bar of the railway track is estimated.

EFFECT: accuracy and reliability of automatic monitoring of the state of rail sections of the railway track is increased.

2 cl, 7 dwg

Description

The invention relates to methods for non-destructive testing of materials by studying stray magnetic fields and can be used in the current maintenance and maintenance of railway (railway) tracks, in particular, when monitoring seamless rail lashes in order to prevent violations of track stability under the influence of longitudinal temperature forces.

Many railways in the world operate a temperature-stressed jointless track structure. The main difference between the work of a seamless track and a link one is that in rail lashes welded from 800 m and up to a stage, there are significant mechanical stresses caused by temperature changes. With an increase in the temperature of the rail lashes in comparison with the fixing temperature, the rails elongate, which cause mechanical stresses, which can lead to a sharp violation of the longitudinal stability (“ejection”) of the track. When the temperature drops, the rails are compressed, which can lead to a break in the lash and the formation of a large gap that is dangerous for the passage of the train, or a rupture of the rail joint due to the shear of the bolts.

On the Russian railway network, on average, up to 10 failures occur per year associated with the ejection of a rail-sleeper grid or a break in the whip. In 2021, 5 derailments of freight trains were allowed due to track overshoot [1]. Enhanced monitoring of the state of rail lashes is required when extreme (for a given area) and close to them air temperatures occur [2, 3].

The jointless track consists of rail lashes (800 m or more in length) and leveling spans of several (from two to 4) links with a rail length of 12.5 or 25 m. During operation, temporary restoration sites (MTP) may appear in the rail lash, caused by cutting out a defective section of the rail, which is replaced by a rail (cutting) 8-11 m long, forming two bolted joints. In practice, due to urgent work to remove the defective section of the rail lash (cutting cuts in a short time as a matter of priority), the coordinates and value of cutting lengths remain undocumented and not entered into a single database (track passport). At the same time, as statistics show, it is in the zone of location of the places of temporary restoration of the lashes that violations of the longitudinal stability of the continuous track very often occur.

Considering the importance of automatic monitoring of the longitudinally stressed state of the rail lashes of a seamless railway. way, in world practice, many technical solutions and techniques based on different physical principles have been proposed and continue to be proposed. Most often, these solutions are based on ultrasonic methods [4-6], on the estimation of Barkhausen noise intensities [7-9], on tensometry [10-12], and on measuring the magnitude of the displacement of the rail string relative to fixed reference marks. In the latter case, the displacement value is estimated both visually (by operators during inspection [2-3] or by video recording [15-17]) and using various mechanical or electronic [18] means.

Most of the listed technical solutions require autonomous sensors installed on rails with the transmission of recorded information via wireless communication and, of course, require power supply and periodic maintenance. In addition, they must be protected from vandals and ensure operability in a wide (from -55 to +55°C) temperature range. The cost of such sensors and labor costs for their maintenance are significant. Apparently, therefore, the authors do not know examples of the commercial application of these devices.

The limitation of methods by an automated system with optical sensors [15-17] is the impossibility of using them with snow cover, contamination of marks and reference (lighthouse) sleepers, etc.

Known methods for automated monitoring of the state of the rail lashes of the railway. tracks [19-20], based on the analysis of deformation waves caused by the movement of a train on rails, also require significant initial investments and have low reliability of the results obtained.

There is a method for automatically monitoring the state of rail lashes of a seamless track according to [14], including placing and fixing a set consisting of at least three magnetic marks in a given place on the rail track, detecting the position of the marks with a magnetic field sensor installed on a vehicle moving along the track, transferring the detection results to a preprocessing device, processing the results and transferring the preprocessed information to a server device for final processing, analysis and storage, while one of the magnetic marks The test points of the set are placed and fixed directly on the lighthouse (fixed) sleeper, and the rest - on both sides of it at a distance of at least 0.8 m on the rail foot, and the detection results are processed using software that determines the relative position of the marks in the set.

The disadvantage of the known method [14] of automatic control is the low reliability and complexity of implementation in real operating conditions of the rail track. Placing the magnetic marks of the set on the bottom of the rail, at a significant (more than 200 mm for rails of the R65 and UIC-60 types) distance from the detection system (magnetic field sensor) requires sufficiently strong magnets to complete the sensors, sharply increases the cost of the system and reduces the resolution, and hence the accuracy of determining the desired parameters.

In the method for evaluating the theft of a rail lash according to the patent [13], which essentially performs automatic monitoring of the state of the rail lashes of a railway track, sets of marks made of ferromagnetic materials are placed and fixed at specified points on the rail track, one of the marks of the set is placed on the reference sleeper, the second at a known distance from the first on the outer side of the rail head, the marks are detected by a flaw detection tool that periodically moves along the rail track and is equipped with a magnetization system and magnetically sensitive sensors, by comparing the current distance between the marks with the results of previous measurements and with the limit of its permissible value, as well as comparing the displacement of the rail on the nearby reference sleepers, the longitudinal deformation (hijacking) of the rail string is estimated, and the results obtained are stored for further monitoring of the state of the railway track.

A positive feature of the method [13], in contrast to many known methods of track monitoring [4-12 and 14-20], is the use of passive tags that do not require electrical power, special magnets and maintenance. It does not require the development of special equipment and the deployment of a network for transmitting measurement results, because for monitoring, standard flaw detection tools with on-board computer systems and an established data transmission network are used.

The disadvantage of the method [13], taken as a prototype, is the low reliability of automatic monitoring of the state of the rail lashes of the railway track, caused by the evaluation of the longitudinal deformation of the rail lash only by the magnitude of their displacement relative to the reference sleepers. At the same time, the butt gaps in equalizing spans and in places of temporary restoration of the lash are not taken into account, which reduces the reliability of the results and the quality of track monitoring.

The problem solved by the claimed invention is to increase the reliability and reliability of automatic monitoring of the state of the rail lashes of the railway track by collecting additional information about the values of the butt gaps in the leveling spans and the MVP of the rail lashes when monitoring the railway. ways by operating defectoscopic means.

The problem is solved due to the fact that in the method of automatic monitoring of the state of rail lashes of a railway track, including the placement and fixation of sets of marks made of ferromagnetic materials in specified places on the rail track, one of the marks of the set is placed on a reference sleeper, the second is located at a known distance from the first on the rail head, while the detection of marks is carried out by a flaw detection tool that periodically monitors the rail tracks, equipped with a magnetization system and magnetically sensitive sensors, the displacement is estimated rail lash by comparing the current distance between pairs of marks with the results of previous measurements and with acceptable values, also comparing the displacement of the rail on nearby reference sleepers, save the results obtained, additionally, according to the signals of the magnetically sensitive sensor caused by the scattering of the magnetic field in the area of the butt gap, bolted joints of the rail track are detected, the magnitudes of the butt gaps are determined from the amplitude and spatial characteristics of these signals, by joint analysis of the values of the butt gaps and displacements of the rail lashes it is used to assess the state of the rail track with respect to the fiducial marks. Moreover, the monitoring periods are adjusted taking into account the current and predicted temperature of the rails.

Distinctive features of the proposed method in comparison with the prototype and the prior art are:

1. According to the signals of the magnetically sensitive sensor caused by the scattering of the magnetic field in the zone of the butt gap, the bolted joints of the rail track (equalizing spans and MVP) are determined. In the method adopted for the prototype, the definition of bolted joints is not provided.

2. According to the amplitude and spatial characteristics of the signals caused by the scattering of the magnetic field in the gap zone of the bolted joint, the values of the butt gaps are estimated. It is obvious that with thermal deformation of the rail lash, not only the distances between the marks (on the rail and the reference sleeper) change, but also the values of the butt gaps adjacent to the rail lash. Taking them into account makes it possible to more fully and reliably assess the state of the railway. way. In the prototype, this important factor for monitoring the state of the railway. paths are not taken into account. Under real operating conditions of a seamless track, periodic measurements of butt gaps are carried out manually using a metal wedge or a universal template model 00316 [3].

3. According to the joint analysis of the values of the butt gaps and displacements of the rail lashes relative to the fiducial marks, the state of the rail lash of the railway is assessed. way. A comprehensive analysis of several factors (displacement of the lash relative to the reference sleepers, changes in the values of the butt gaps, including joints that are often not taken into account in the MVP zone), makes it possible to increase the reliability and reliability of automatic monitoring of the state of the railway track.

4. The measurement periods are corrected taking into account the current temperatures and the forecast of their change. Obviously, depending on the weather conditions, with the onset of temperatures close to the highest for a given area, the dynamics of the longitudinal deformation of the rail track increases. Correction of monitoring periods taking into account this factor allows you to respond in a timely manner to a breakdown in the path and prevent undesirable consequences. In the prototype, the issues of choosing monitoring periods are not considered.

Thus, the set of distinguishing features of the proposed method allows to obtain the required technical result: increasing the reliability and reliability of automatic monitoring of the state of the rail lashes of the railway track and, as a result, increasing the safety of the rail track.

The possibility of implementing the proposed method is demonstrated by the following illustrative materials:

Fig. 1 - a fragment of the defectogram of the magnetic channel of one line of the rail track recorded by the flaw detection tool, where:

1 - defectogram;

2 - signals from bolted joints;

3 - leveling span (zone of discharge rails with links of length l _r );

4 - place of temporary restoration of the path (temporary rail or cutting length l _n ).

Fig. 2 - the signal form of the induction sensor (Fig. 2b), when the magnetizing system with the sensor passes over the area of the bolted joint (Fig. 1a), where:

5 - controlled railway rail;

6 - bolted joint area with pads 7 and butt gap 8;

2 - signal from the butt gap 8 and reactions 9 and 10 from the beginning and from the end of the butt plates 7 when they are fixed by an inductive sensor (Fig. 2b).

Fig. 3. An enlarged view of the signal 2 (Fig. 1) from the butt gap 8, where:

a - amplitude (range) of the signal;

w is the width of the positive ejection;

d is the distance between signal extrema.

Fig. 4 - experimental dependences of the signal parameters on the size of the butt gap 8 in the measurement range.

Fig. 5 - experimental dependences of the signal parameters on the size of the butt gap 8 at small values.

Fig. 6 - an example of placing marks made of ferromagnetic material on a reference sleeper (red corner bracket) and on a rail.

Fig. 7 - signals from a pair of marks (left from the mark on the rail, right - from the mark on the lighthouse sleeper), obtained during the passage of the flaw detection tool (at a speed of 30 km/h).

The method is implemented as follows. As a vehicle, a mobile flaw detection tool is used that implements the magnetic method of flaw detection (in foreign literature - MFL). This makes it possible to use passive ferromagnetic materials as a set of tags (Fig. 6), which do not require electrical power and a magnetic field source.

The specified means (not shown in Fig.), equipped with a navigation system (odometers, GLONASS / GPS systems) and an on-board computer system, moves along the rail track at a given speed. The magnetization system of the flaw detection tool, which mainly consists of electromagnetic coils (solenoids) mounted on the axles of wheel pairs of a biaxial bogie (not shown in Fig.), creates a constant magnetic flux in the sections of rails located between the poles of the electromagnet (contact spots of wheel pairs with rails) in a known way [21, 22].

In the general case, traditional "U"-shaped electromagnets suspended on both sides of the trolley of the flaw detection tool above the railway rails can also be used as a magnetizing system. way, however, the monitoring results in this case will be worse due to the inevitable fluctuation of the technological gap between the poles of the moving electromagnet and the rail running surface.

Magnetically sensitive sensors (not shown in Fig.) installed on the rail running surface in the interpolar space perceive magnetic field anomalies: generated by defects and structural elements of the rail track (turnouts, bolted joints and gaps between the rails to be connected, welds, etc.) and signals from marks mounted on the rail head and reference sleepers. The received signals (see defectogram 1 in Fig. 1), through the amplifier, analog-to-digital converter, enter the computer (the last elements are obvious and not shown for the sake of simplicity).

Induction coils can be used as magnetically sensitive sensors when implementing the method; Hall sensors (single or in the form of rulers or a matrix); thin-film magnetoresistive sensors [23]. Induction sensors, as the most reliable for operation in a wide temperature range and easy to operate, are preferable for implementing the method. When using Hall sensors, the incoming signals must first be subjected to a differentiation operation.

In the process of scanning rails 5 (Fig. 2) in the general flow of signals sequentially received by magnetically sensitive sensors and recorded on defectogram 1 (Fig. 1), signals 2 from bolted joints 6 of compensation spans 3 and MVP 4 can be distinguished by their characteristic features. Such signs are the presence of signals (responses 9 and 10 in Fig. 2b) from the ends of the butt plates 7 and a signal 2 of a significant amplitude of a certain shape (Figs. 1 and 2) from the butt gap 8 in the middle between the ends of the plates [24 and 25]. The reliability of recognition of signals from bolted joints can be further improved using special processing [26]. As a rule, the amplitudes of signals from butt gaps (Fig. 1) are of the greatest importance compared to signals from welded joints and potential rail defects. Based on this feature and with the use of technical solutions according to patents [21, 27, 28], it is possible to recognize signals from butt gaps against the background of other signals with high reliability.

Signals from pairs of marks mounted on the head of the rail 5 and reference sleeper (see Fig. 7) are recognized by a predetermined distance L ₀ between the pairs. Moreover, during operation, this distance L is within

L ₀ - Δl _max ≤ L ≤ L ₀ + Δl _max ,

where Δl _max - the maximum possible displacement of the rail lash in the region of laying the railway. track (according to the current NTD Δl _max ≤ 20 mm). During experimental verification of the proposed method, the initial distance L ₀ between pairs of marks was chosen to be 200 mm. Obviously, in the general case, the value of L ₀ may have other values that are a multiple of the measured value of the displacement Δl of the rail string.

According to the specified algorithm, the selection of signals from the marks and the estimation of the displacement of the rail string relative to the reference sleeper is carried out by the processing system (computer).

Processing and analysis of signals directly on board the diagnostic tool makes it possible to obtain monitoring results almost in real time and promptly take preventive measures for the technical maintenance of the track, taking into account the specifics of the monitored section and local features. Current monitoring data can be stored both in the database of the flaw detection tool and in the EKASUI database (unified corporate system for automatic infrastructure management) for comparative analysis over time. The automatic processing algorithm is obvious for specialists in this field and does not require additional explanations.

Naturally, in accordance with [2, 3], when monitoring the displacements of the rail string relative to the reference marks (lighthouse sleepers) and determining the butt gaps, it is necessary to take into account both the temperature of the rail string laying and the current operating temperature. Daily and long-term forecasts of rail temperatures are observed and formed on special temperature stands of track distances and the geophysical station of the Directorate of Railway Infrastructure. Taking into account these forecasts, in accordance with the claimed method, it is necessary to correct the periods of measurements (passages of the flaw detection tool) on the observed section of the railway. way.

Thus, the implementation of the attached method for automatic monitoring of the state of rail lashes of the railway. transport makes it possible to ensure high reliability of monitoring results by taking into account the indicators of a complex of interrelated factors: rail temperature, displacements of the rail string relative to fixed reference marks and butt gaps.

Information sources

1. Fadeev B.C., Konakov A.V., Matskevich M.V. Device for determining the temperature of fixing the rail whip. // Way and track facilities. No. 7. pp. 37-39.

2. Instructions for laying, maintaining and repairing a seamless track. Russian Railways No. 2544/r dated December 14, 2016 (as amended on September 9, 2022).

3. Instructions for the current maintenance of the railway track. No. 2288r dated November 14, 2016

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Claims (2)

1. A method for automatic monitoring of the state of rail lashes of a railway track, including placing and fixing sets of marks made of ferromagnetic materials at specified locations on the rail track, one of the marks of the set is placed on a reference sleeper, the second is located at a known distance from the first on the rail head, and the marks are detected by a flaw detection tool that periodically monitors the rail tracks, equipped with a magnetization system and magnetically sensitive sensors, the displacement of the rail lash is estimated by comparing the current distance between the pairs the marks with the results of previous measurements and with acceptable values, also comparing the displacements of the rail on the nearby reference sleepers, save the results obtained, characterized in that the signals of the magnetically sensitive sensor caused by the scattering of the magnetic field in the area of the butt gap detect the bolted joints of the rail track, the amplitude and spatial characteristics of these signals determine the magnitude of the butt gaps, by joint analysis of the values of the butt gaps and displacements of the rail strings relative to the reference marks ok evaluate the state of the rail lash of the railway track. 2. The method of automatic monitoring of the state of the rail lashes of the railway track according to claim 1, characterized in that the measurement periods are corrected taking into account the forecast of changes in the temperature of the rails.