RU2703802C1 - Method for determination of distances between rail-track sleepers - Google Patents

Abstract

FIELD: defectoscopy.

SUBSTANCE: invention relates to methods and means of nondestructive inspection of materials and can be used for diagnostics of rail-tracks. Method of determining distances between track sleepers consists in movement along rail track of meter, in permanent determination of its current position and in contactless probing of rail track, with selection of signals from sleepers, preservation of obtained results, wherein for probing of sleepers a magnetic flaw detector is used, and determination of distances between sleepers is performed by processing of magnetic signals from rail fasteners.

EFFECT: possibility of estimating distances between axes of track sleepers in all climatic zones and under any weather conditions, high efficiency of detecting dangerous displacements of sleepers.

1 cl, 3 dwg

Description

The invention relates to methods and means of non-destructive testing of materials and can be used to diagnose rail tracks, in particular, to measure the relative position of sleepers in order to detect violations of regulatory distances between them.

The distance between the sleepers is an important characteristic of the rail track, ensuring its safety and must comply with regulatory requirements. The order of the sleepers along the length of the rail track is called the sleepers diagram (the number of sleepers per 1 km of track). These diagrams are established by regulatory documents and are different for straight and curved sections of the rail track, in the areas of bolted joints, railroad switches. Basically, 1840 pieces were installed on straight sections of the sleepers diagram, and 2000 pieces in curves of a radius of 1200 m or less. per km of track [1] (ie 500 mm distance between the axles of the sleepers).

Deviations from the plot values are allowed no more than 8 cm with wooden sleepers, no more than 4 cm with reinforced concrete sleepers. Otherwise, the violation of the geometry of the track can lead to the rapid destruction of sleepers, rails, and the track as a whole.

The distance between the sleepers can be measured manually using traditional tools: rulers, tape measures, calipers, etc.

Obviously, such measurements are time consuming and time consuming.

Known [2] Patent RU 2521095, in which it is shown that magnetodynamic (MD) flaw detectors, moving along a rail track, can operate at high speeds, in all climatic zones and under any weather conditions. They have high reliability of measurements, providing good repeatability of the results. They can detect structural elements of the rail track: bolted and welded joints of rails, turnouts, butt plates, etc. In particular, MD flaw detectors are capable of detecting rail fastenings (metal linings, embedded bolts, terminals), i.e. sleepers.

The patent [2] considers the diagnosis of rail defects in various ways: ultrasonic and MD. In this case, the flaw detector signals are also used for coordinate reference of the flaw detector to the rail track.

Known means for moving sleepers [3] Patent SU 1449613, [4] US 5671679, capable of restoring the required orientation of sleepers, according to the corresponding sensors. But during the operation of the rail track, it is first necessary to determine the sections of the track where the normative distances between the sleepers are violated.

Closest to the claimed is [5] Patent RU 2228988, a method of measuring the distance between the sleepers, which consists in moving along the track of the meter, constantly determining its current position and contactlessly sensing the rail track, extracting signals from the sleepers, storing the results and calculating the distance between the sleepers . The method involves:

1. The presence of the meter between the sleeper distances as part of the repair tool - tamping machine.

2. For sounding it is proposed to use:

- acoustic range meters, allowing to detect sleepers by the difference in distance from the sensor to the sleepers or gravel;

- optical means, for example, video cameras, allowing to determine the distance between the sleepers from the video image of the rail track.

The disadvantages of the method [5] are:

1. Low efficiency of detecting violations of the distances between the sleepers. Repair tools, such as a tamping machine, usually move at low speed, occupying the rail track for a long time, and therefore such measurements and repairs are rarely carried out. This leads to the feasibility of separating the measurement and repair processes, entrusting the task of measuring interspersed distances to high-speed flaw detectors: flaw detectors, railcars, etc., and solving the problems found on tamping machines.

2. Limited application possibilities. The acoustic and optical means of detecting sleepers are limited by weather conditions, such as snow. In addition, video processing is not accurate and time consuming.

The problem solved by the claimed method is the detection of railroad ties and estimation of the distances between them using high-speed flaw detection tools with the subsequent departure of repair units to a specific section of the rail track.

To solve this problem, in the proposed method for determining the distance between the sleepers of the rail track, which consists in moving along the track of the meter, constantly determining its current position and contactlessly sensing the rail track, extracting signals from the sleepers, storing the results, and magnetic probe is used to probe the sleepers flaw detector, and the determination of the distances between the sleepers is carried out by processing magnetic signals from rail fasteners.

The technical results of using the proposed method are:

1. The ability to assess the distances between the axles of the railway sleepers in all climatic zones and under any weather conditions.

2. Improving the efficiency of detection of dangerous displacements of sleepers through the use of high-speed flaw detection tools, which quite often (several times a month) diagnose the rail track.

3. Low implementation costs due to the use of the existing magnetodynamic high-speed flaw detector means with the introduction of new software.

The inventive method is illustrated by the following graphic materials.

FIG. 1. A fragment of a defectogram of a magnetic flaw detector (Fig. 1a) and a video fragment of a part of the same section with three sleepers (Fig. 1b), where:

1 - signals from a magnetic flaw detector (“lining process” according to [7]) from sleepers;

2 - image of the rail in the video fragment;

3 - rail fastenings and sleepers;

A, B and C - sleepers (rail fastenings are visible) on the video fragment and signals from them on the defectogram.

FIG. 2. The results of processing the magnetic control signals of the proposed method on a track section of about 16 m (Fig. 2a), and a small section of this fragment (Fig 2b) highlighted in (Fig. 2a) with a rectangular frame, where:

1 - signals of the magnetic channel from rail fastenings (to simplify the analysis in Fig. 2a, the serial numbers of the half-waves of the defectogram, and hence the sleepers, are indicated by serial numbers in small sizes: 1-5, 10, 15, 20 and 25);

4 - the same signal 1, shifted by 500 mm;

5 - deviations from the normalized value presented on the coordinate plane "deviations, in mm - the longitudinal coordinate of the path, in mm". Signals 1 and 4 on the same plane in FIG. 2 are given for illustrative processing.

FIG. 3. The signal of the magnetic flaw detector on the rail section of 1.1 km (Fig. 3a) and the results of processing these signals by the proposed method (Fig. 3b).

Consider the possibility of implementing the proposed method.

The MD flaw detection method consists in exciting the magnetic flux in the rail with a magnetization system in the form of U-shaped magnets or solenoids mounted on the axles of the wheelsets, and receiving signals from anomalies by magnetic field sensors located on the rail rolling surface [6]. When monitoring the condition of the rail track, a movable flaw detector, (flaw car, motor car, etc., not shown in Fig.), Is moved along the rail with a magnetic flaw detector 2. They are probed with a magnetic flaw detector excitation coils that create magnetic flux in the rail and magnetic scattering field around the rail. The sensor (or sensors) of the magnetic flaw detector receives the response signals 1, which through the amplifier, analog-to-digital converter enter the computer (the last elements are obvious and not shown for the purpose of simplification). The sources of signals of anomalies of the MD flaw detector can be:

- defects in the rail heads at a depth of up to 20 mm, causing a “displacement” of the main magnetic flux from the rail and detected by magnetic field sensors with sufficiently large amplitudes.

- rail joints, bolt plates, turnouts, rail linings and rail fastenings of the railway track. In addition to the main flux created by the magnetizing system in the metal of the rail head, a scattering field arises in the process of magnetization. Due to this field, some metal structural elements of the track surrounding the rail (butt pads, rail fastenings) can be detected and evaluated using appropriate processing algorithms [6].

In FIG. Figure 1a shows a fragment of a magnetic channel defectogram with the results of monitoring a real rail track, where the minima of a line similar to a sinusoid (“lining process” according to [7]) correspond to rail fastenings. The latter, in turn, are attached to reinforced concrete sleepers using embedded bolts, in connection with which the position of the sleepers can be determined by the position of the rail fastening.

In FIG. 16 shows a video fragment of the same section of the rail track (one string) with three sleepers A, B and C. From the comparisons of FIG. 1a and 1b, one can see in principle the possibility of determining the distance between the sleepers by determining the distance between the negative 'humps' on the magnetic channel. However, the visual processing at the accepted scales of signal representation (at least 25 m per screen) and the implemented sampling resolution (2 mm of the track coordinate) does not have the necessary reliability and is very laborious.

To automate the process of determining the position of the sleepers of the proposed method, the corresponding signal processing of the magnetic control method is performed. As an example, we show the possibility of using correlation analysis to accomplish the task.

1. Consider a fragment of the sampled signal 1 (Fig. 2) of the magnetic sensor on a segment approximately equal to the expected distance between the sleepers - (for example, for a plot of 2000 sleepers per km of track), at a distance L = 0.5 m: x _{iK / 2} ... x _{i + K / 2-1} .

The number of elements K in the considered sequence depends on the sampling step - for example, at a sampling step of 2 mm, it is L / 2 mm = 250.

2. Consider another fragment of the sampled signal 4, shifted relative to the first one by a distance approximately equal to the expected distance between the sleepers (Fig. 2b)

x _{i + K / 2 + S} ... x _{i + 3K / 2 + S-1} ,

where S is an additional shift whose magnitude is small compared to K.

3. We will look for the cross-correlation coefficient between two fragments C _i , considering it as a function of S:

and define the maximum C _i (S). For the true deviation of the sleeper distance from the expected s _i, we take the shift value S at which the maximum cross-correlation coefficient is reached:

Thus, a point with any longitudinal coordinate i can be associated with a number s _i , which will describe the deviation of the inter-sleeper distance from the expected one (line 5 in Fig. 2).

On the given fragment of the defectogram (Fig. 2a), in particular, it can be seen that in the area of the sleepers No. 15-18 (numbering relative to the beginning of the fragment), a decrease in the distances between the sleepers by 30-50 mm, and in the area of the sleepers No. 20 and 25, an increase in the distances 30 mm. Which coincides with the measurements performed by traditional methods with access to a physical examination.

In FIG. 3 shows the initial magnetic defectogram (Fig. 3a) and the results of the analysis of the proposed method (Fig. 3b). It can be seen from the defectogram (Fig. 3a) that the considered track section with a length of just over 1 km consists of a jointless section, where bolt joints are occasionally present (several vertical lines on the defectogram) corresponding to the discharge links. From the results of processing by the proposed method it follows (Fig. 3b) that in the longitudinal coordinate section from the beginning of the fragment to 1200000 mm, the number of sleepers per km corresponds to a plot of 2000 sleepers / km (average distance 500 mm), it is obvious that this curve is a track section. In the area from 1200000 mm to 1800000 mm, the distance between the sleepers varies (average value 550 mm or plot 1840 sleepers / km), which corresponds to a straight section of the rail track.

As shown above, a detailed analysis of the distances between each sleepers can be performed on an enlarged scale (see Fig. 2 is a fragment of a 16-m track section with coordinates 2404 to 2420 m). It can be seen that in this section, three interspecial distances are less than the standard by almost 50 mm, and three are above the average by 30 mm (within the tolerance for reinforced concrete sleepers).

Note that correlation analysis is not the only way to process magnetic channel signals to determine the desired parameter. You can, for example, conduct a frequency analysis and monitor the phase change. Finally, you can significantly smooth out the signal and monitor the transitions through 0. In order to avoid narrowing the claims, a specific analysis method is proposed not to be indicated in the claims.

Thus, the claimed method solves the problem of automatic detection of railway sleepers and estimates the distances between them using high-speed magnetic flaw detectors. The technical result of the method is the ability to estimate the distances between the sleepers of the rail track in all climatic zones and under any weather conditions with a frequency of diagnostics of the rail track. Particularly valuable in the proposed technical solution is that a positive technical result is achieved without a significant change in the current rail track diagnostics system. The efficiency of the proposed technical solution has been proven in the diagnosis of rail tracks by a flaw detector car with AVIKON-03M equipment.

When implementing the proposed method, simultaneously with the determination of the distances between the sleepers, it is possible to documently differentiate the controlled driving distance to curves and straight sections of the track, which is very important for automated interpretation of defectograms.

Information sources

1. Kreinis Z. L., Fedorov I.V. Railway track M .: UMK MPS of Russia, 2000 .-- 368 p. (see page 142.).

2. RU 2521095.

3. SU 1449613.

4. US 5671679.

5. RU 2228988.

6. RU 2578897.

7. Markov AA, Kuznetsova EA, Defectoscopy of rails. The formation and analysis of signals. Book 2. Explanation of defectograms. A practical guide in two books, edited by Doctor of Technical Sciences A.A. Markova, St. Petersburg: Ultra Print, 2014 .-- 332 p.

Claims (1)

The method for determining the distances between the railroad ties, which consists in moving the meter along the rail, constantly determining its current position and contactlessly sensing the rail, extracting signals from the sleepers, storing the results, characterized in that a magnetic flaw detector is used to probe the sleepers, and determining the distance between the sleepers is made by processing magnetic signals from rail fasteners.

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