Rail flaw detection device for vehicle

Abstract

To provide a rail flaw detection device for vehicle capable of performing high-precision rail flaw detection while avoiding the occurrence of false images (pseudo echoes) even if a vehicle speed is increased to equal to or greater than 50 km / h.SOLUTION: In a rail flaw detection device for vehicle which is mounted on a vehicle traveling on a rail, in which a plurality of probes is arranged so as to be in contact with the top surface of the rail being an inspection target, and ultrasonic waves are transmitted at a predetermined pitch from ultrasonic transducers during vehicle travel, and internal flaws in the rail are detected on the basis of reception signals from the probes, one of the plurality of probes is configured as a shared probe comprising: one ultrasonic transducer that transmits ultrasonic waves in the longitudinal direction of the rail at a predetermined angle with respect to the top surface of the rail and receives echoes; and one ultrasonic transducer that is arranged at a position separated from the ultrasonic transducer, receives echoes of the ultrasonic waves transmitted from the ultrasonic transducer and detects internal flaws of the rail using a tandem method.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a rail flaw detection device for vehicles equipped with a sliding ultrasonic probe, and particularly to a rail flaw detection device for vehicles suitable for detecting flaws inside rails while the vehicle is running after being mounted on the vehicle.

Background Art

[0002] As a method of rail management for railway tracks, an inspection technique for checking the presence or absence of flaws generated in the rails by an ultrasonic flaw detection device is known. In addition, as shown in FIG. 9, some ultrasonic rail flaw detection devices are configured such that a transmitting probe and a receiving probe are arranged side by side in contact with the rail surface, and the reflected wave of the ultrasonic wave transmitted from the transmitting probe is received by the receiving probe, and the flaw inside the rail is detected by measuring the reflected wave intensity. Note that the conventional rail flaw detection device is generally a hand-held type in which the device is moved while walking along the rail with a handle, and there is a problem that the burden on the operator is large.

[0003] Therefore, an ultrasonic rail flaw detection device has been proposed and put into practical use, which is mounted on a vehicle such as an inspection vehicle and detects flaws inside the rail while the vehicle is running. In this ultrasonic rail flaw detection device, a plurality of ultrasonic probes (hereinafter simply referred to as probes) having different ultrasonic transmission angles are arranged in a row along the rail extension direction, and one of the probes is constituted by a tandem probe for flaw detection by the tandem method. The tandem probe is provided mainly for detecting vertical crack flaws existing in the rail welded portion.

[0004] In the rail flaw detector for vehicles that has been put into practical use so far, in order to improve the detection accuracy, as shown in FIG. 6, the ultrasonic emission angle of the tandem probe 11E is 37 degrees, and the ultrasonic emission angles of a pair of diagonal probes 11D1 and 11D2 for detecting transverse cracks and bolt hole defects from the rail head to the bottom are set to ±40 degrees. In addition, a pair of diagonal probes 11A1 and 11A2 with an ultrasonic emission angle of ±70 degrees and a pair of vertical probes 11B1 and 11B2 with an ultrasonic emission angle of 0 degrees are provided.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The upper limit speed during measurement of a vehicle (maintenance vehicle) equipped with a currently practical rail flaw detector is limited to 40 km / h from the viewpoint of detection accuracy and the like, and in order to prevent interference between a plurality of probes, the flaw detection pitch by the probes was set to 2.0 mm. Specifically, the time required for the ultrasonic wave transmitted from the probe to travel back and forth (including the propagation time in the probe) is about 160 μS when the rail height is 180 mm for a probe with an ultrasonic emission angle of 45 degrees. Considering the distance (slightly less than 2.0 mm) that a vehicle traveling at a speed of 40 km / h advances during that time, the flaw detection pitch was set to 2.0 mm.

[0007] As described above, the upper limit speed during measurement of the maintenance vehicle equipped with the rail flaw detector is 40 km / h, and the detectable distance during the night time when no operating train is running was not sufficient. Therefore, the inventors considered increasing the upper limit speed during measurement of the maintenance vehicle to 70 km / h. However, if the maximum speed is increased to 70 km / h while setting the flaw detection pitch to 2.0 mm, interference will occur between the probe and the ultrasonic wave it sent immediately before. Therefore, it was considered to set the flaw detection pitch to 4.0 mm. However, when the beam width of the ultrasonic wave emitted from the probe is 10 mm and the flaw detection pitch is 4.0 mm, as shown in Fig. 7(A), flaws that could be detected with a flaw detection pitch of 2.0 mm could not be detected sufficiently as shown in Fig. 7(B), and it became clear that there is a problem that the detection accuracy decreases.

[0008] Therefore, it was considered to double the width of the ultrasonic beam compared to the conventional one. As a method of doubling the width of the ultrasonic beam, a method of making the probe that is the emission source longer and a method of providing two sets of the same probes as before and combining the measurement results for determination can be considered. However, the method of providing two sets of the latter probes will result in a significant cost increase. Also, due to the structure of the probe, even if the length of the vibrator is doubled, the length of the probe itself will not simply become twice as long, so the method of making the vibrator longer was adopted.

[0009] Then, actually, a long probe with a beam width of the ultrasonic wave doubled was created, a rail flaw detector using the long probe was mounted on the maintenance vehicle, and the speed of the maintenance vehicle was increased to 40 km / h or more to conduct a rail flaw detection test. As a result, when the speed exceeds 50 km / h, for example, as shown in Figs. 8(A) and (B), it was found that there is a problem that virtual images (pseudo echoes) occur at positions surrounded by circles, and the positions where the virtual images occur are near the play of the rail.

[0010] Note that the gap of the rail to be inspected is filled with an insulator and configured as an adhesive insulation joint. Further, in the adhesive insulation joint, joint plates are abutted against the left and right sides of the rail web, and the joint plates are joined by a plurality of bolts penetrating the rail web. In FIG. 8, a plurality of patterns arranged side by side in the middle in the height direction are real images detecting bolt holes. Here, it is known that cracks starting from the bolt holes are likely to occur at locations where the rail has bolt holes, and it is required that the rail flaw detector can detect such cracks.

[0011] The present invention has been made paying attention to the above problems, and an object thereof is to provide a vehicle rail flaw detector equipped with a sliding type probe and mounted on a vehicle to detect flaws inside the rail during running. Even when the vehicle speed is increased to 50 km / h or more, it is possible to perform highly accurate rail flaw detection while avoiding the generation of virtual images (pseudo echoes).

Means for Solving the Problems

[0012] To achieve the above object, the present invention is mounted on a vehicle running on a rail, and a plurality of probes (including probes respectively provided with an ultrasonic vibrator for transmitting ultrasonic waves and an ultrasonic vibrator for receiving ultrasonic waves, and a probe provided with a common ultrasonic vibrator for transmitting ultrasonic waves and receiving ultrasonic waves) provided with ultrasonic vibrators for transmitting and receiving ultrasonic waves are arranged to contact the top surface of the rail to be inspected. In a vehicle rail flaw detector that transmits ultrasonic waves from the ultrasonic vibrator at a predetermined pitch during vehicle running and detects flaws inside the rail based on the received signals of the probes, one of the plurality of probes is configured as a shared probe including one ultrasonic vibrator that transmits ultrasonic waves in the longitudinal direction of the rail at a predetermined angle set in the range of 35 degrees to 45 degrees with respect to the top surface of the rail and receives echoes, and one ultrasonic vibrator that is arranged at a position away from the ultrasonic vibrator and receives echoes of the ultrasonic waves transmitted from the ultrasonic vibrator and detects flaws inside the rail by the tandem method.

[0013] According to the rail flaw detector for vehicles having the above-described configuration, a probe for detecting rail transverse cracks and bolt hole defects and a probe for detecting vertical cracks occurring at the bottom of the rail by the tandem method are provided as one shared probe. Therefore, even if the vehicle speed during inspection is increased, it is possible to prevent interference between the ultrasonic waves oscillated by the probe itself due to the reflection of ultrasonic waves at the rail end face, thereby avoiding the generation of virtual images (pseudo echoes) and performing highly accurate rail flaw detection.

[0014] In addition, since the two probes that were conventionally provided as separate probes are combined into one, even when the probe is lengthened and the width of the ultrasonic beam is increased to avoid a decrease in the defect detection rate due to an increase in the flaw detection pitch, it can be made shorter than the total length when the individual probes are arranged as in the prior art, so it can be arranged within a limited space. Here, the desirable range of the predetermined angle is 35 degrees to 45 degrees. Also, the upper limit of the traveling speed of the vehicle is 70 km / h, and the predetermined pitch is preferably set to 3 to 5 mm.

Advantages of the Invention

[0015] According to the rail flaw detector for vehicles according to the present invention, even when the vehicle speed during measurement is increased to 50 km / h or more, it is possible to avoid the generation of virtual images (pseudo echoes) and perform highly accurate rail flaw detection. Also, even when the vibrator is lengthened and the width of the ultrasonic beam is increased, there is an effect that it can be made shorter than the total length when the individual probes are arranged as in the prior art.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0017] Hereinafter, with reference to the drawings, an embodiment of the rail flaw detector according to the present invention will be described in detail. First, the background leading to the recollection of the rail flaw detector of the present embodiment will be described. FIG. 1 is a schematic diagram showing the paths of ultrasonic beams transmitted into the rail R from the probe 11B with an ultrasonic transmission angle of 0 degrees, the tandem probe 11E, and the probe 11D with an angle of 40 degrees in a conventional rail flaw detector. In FIG. 1, the solid line represents the beam path during flaw detection, and the dotted line represents the beam path when there is no flaw to be detected inside the rail. Also, the vertical line on the right end represents the rail end face corresponding to the clearance. The ultrasonic beams transmitted from each probe are repeatedly reflected by the rail bottom face and the top face and travel in the longitudinal direction of the rail. When they reach the end face, they are reflected and travel in the opposite direction.

[0018] In the rail flaw detector used in the tests by the present inventors, when the vehicle travels at a speed of around 55 km / h, while the ultrasonic beam transmitted from the tandem probe 11E reaches the rail end face at the position shown in FIG. 1, the probe 11D with an angle of 40 degrees moves to a position as shown by the broken line A. Therefore, the ultrasonic wave reflected by the end face is mixed into the probe 11D with an angle of 40 degrees and is drawn as a detection signal of the probe 11D with an angle of 40 degrees. On the other hand, when the vehicle speed is lower than 50 km / h, the ultrasonic wave reflected by the end face is not mixed into the probe 11D with an angle of 40 degrees.

[0019] FIG. 2 shows the timing of ultrasonic transmission → drawing range and the mixing / delay signal (end face reflected wave) of the rail flaw detector during low-speed running and high-speed running. Note that the flaw detection pitch is fixed at 4.0 mm regardless of the vehicle speed. However, the flaw detection pitch is not limited to 4.0 mm and may be in the range of 3 to 5 mm. As shown in FIG. 2(A), during low-speed running, since the transmission interval is long, the mixing / delay signal does not overlap with the next ultrasonic transmission → drawing range. On the other hand, during high-speed running, since the transmission interval is short, as shown in FIG. 2(B), the mixing / delay signal overlaps with the next ultrasonic transmission → drawing range. This is the cause of the generation of virtual images (pseudo echoes) as shown in FIGS. 8(A) and (B).

[0020] Here, in order to prevent the relationship between the ultrasonic transmission → drawing range and the interference and delay signals from being as shown in Fig. 2(B), it is conceivable to make the distance between the probes sufficiently long. However, considering the size of the cart on which the rail flaw detector is installed, it was found that it is difficult to set the distance between the probes to the length required to prevent virtual images. Therefore, the inventors of the present invention developed a new probe that shares the ultrasonic vibrator of the tandem probe and the ultrasonic vibrator of the 40-degree probe.

[0021] Fig. 3(A) shows an example of the probe arrangement in a rail flaw detector using the newly developed shared probe, and Fig. 3(B) shows the schematic configuration of the newly developed shared probe. As shown in Fig. 3(A), the probe arrangement 11 in the rail flaw detector of the present embodiment mainly includes a pair of diagonal probes 11A1 and 11A2 with an ultrasonic transmission angle of ±70 degrees for detecting head transverse cracks in the surface layer of the rail R, a pair of vertical probes 11B1 and 11B2 with an ultrasonic transmission angle of 0 degrees for mainly detecting horizontal defects, a tandem and -40-degree shared probe 11C, and a probe 11D with an ultrasonic transmission angle of +40 degrees for mainly detecting rail transverse cracks and bolt hole defects. In the present invention, the side where the engine is mounted is taken as the main direction from the center of the vehicle, and the probes on the main direction side are denoted as + (plus), and the probes on the sub-direction side are denoted as - (minus).

[0022] Among the above-mentioned plurality of probes, a pair of diagonal probes 11A1 and 11A2 with ±70 degrees and a probe 11D with +40 degrees each have one ultrasonic vibrator, and the probes 11B1 and 11B2 with 0 degrees have two ultrasonic vibrators. Also, among the probes 11B1 and 11B2 with 0 degrees, one probe 11B1 is a probe with a frequency of 5 MHz targeting shelling defects and head horizontal cracks near the rail head, and the other probe 11B2 is a probe with a frequency of 2 MHz targeting rail head, abdomen, and bottom horizontal cracks. Note that the probes may be those equipped with an ultrasonic vibrator for transmitting and receiving ultrasonic waves, or those separately equipped with an ultrasonic vibrator for transmitting ultrasonic waves and an ultrasonic vibrator for receiving ultrasonic waves.

[0023] As shown in FIG. 3(B), the common probe 11C has one ultrasonic vibrator UV with a transmission angle set to 37 to 43 degrees, and transmits and receives as a -40-degree probe. Further, as shown in FIG. 3(C), an ultrasonic vibrator US is arranged at a position away from the ultrasonic vibrator UV in the common probe 11C as a receiving vibrator of the tandem probe. The reason why the transmission angle of the ultrasonic vibrator UV in the common probe 11C is set to 37 to 43 degrees is to be paired with 11D. Note that the ultrasonic transmission angle of the ultrasonic vibrator UV of the common probe 11C may be in the range of 35 degrees to 45 degrees.

[0024] FIG. 4 shows an overall configuration example of a rail flaw detector including a probe array including the common probe shown in FIG. 3. As shown in FIG. 4, the rail flaw detector of this embodiment is provided corresponding to each of the probes 11A1, 11A2 to 11D constituting the probe array 11, and includes transmission-reception circuits 12A to 12F that transmit a transmission pulse signal to each probe and amplify the signal received by each probe, and an oscillation circuit 13 that generates an oscillation signal having a frequency such as 2 MHz or 5 MHz and supplies it to the transmission-reception circuits 12A to 12F.

[0025] The rail flaw detector also includes a signal processing unit 14 that processes the signals amplified by the transmission-reception circuits 12A to 12F, and a moving distance calculation circuit 16 that calculates the moving distance of the vehicle based on a signal from a vehicle speed sensor 15 such as a tachogenerator that is provided on, for example, an axle of a train and detects the rotational speed of a traveling drive motor. The rail flaw detector further includes a trigger signal generation circuit 17 that generates a trigger signal for causing the transmission-reception circuits 12A to 12F to transmit a transmission pulse signal at, for example, a 4 mm pitch regardless of the vehicle speed based on the calculated distance information.

[0026] The signal processing unit 14 includes time gate means for receiving the signals amplified by the transmission-reception circuits 12A to 12F for a predetermined reception time for each probe, signal comparison means for comparing the received signal that has passed through the time gate means with a predetermined threshold value and extracting only echoes with a reception intensity higher than the threshold value, and evaluation means for evaluating flaws for echoes exceeding the threshold value.

[0027] Furthermore, the rail flaw detector includes a display unit 18 that displays the echo extracted by the signal processing unit 14 as an image, and a storage unit 19 that stores an image generated by image processing, a result evaluated by the evaluation means, and the like. Note that the functions provided in the signal processing unit 14 can be realized by cooperation with an MPU (microprocessor) and a program executed by the MPU.

[0028] The inventors of the present invention prototyped a rail flaw detector having the above-described configuration, mounted it on a vehicle, and conducted a test for detecting a rail while traveling at a speed of 70 km / h. An example of an image obtained from the test results is shown in FIG. 5. As can be seen by comparing FIGS. 5(A) and (B) with FIGS. 8(A) and (B) described above, the virtual image that appeared near the clearance of the rail in the conventional rail flaw detector has disappeared. In FIGS. 5 and 8, a plurality of patterns arranged side by side on the left and right at the middle in the height direction are real images in which bolt holes are detected.

[0029] As described above, according to the rail flaw detector of the above-described embodiment, since the probe for detecting a rail transverse crack and a bolt hole flaw and the probe for detecting a vertical crack generated near the bottom by the tandem method are provided as one shared probe, even if the vehicle speed is increased, interference between the probes due to reflection of ultrasonic waves at the rail end face can be prevented, and thereby high-precision rail flaw detection can be performed while avoiding the generation of a virtual image (pseudo echo).

[0030] In addition, since the two probes that were conventionally provided as separate probes are combined into one, even when the probe is lengthened to avoid a decrease in the flaw detection rate due to an increase in the flaw detection pitch and the width of the ultrasonic beam is increased, the length of the probe array can be shortened compared to the conventional case, and it can be arranged within a limited space.

[0031] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. For example, in the probe (FIG. 3(A)) of the above embodiment, a plurality of probes are arranged in contact with each other, but if there is room in the arrangement space, they may be arranged at intervals within that range. Also, the order of the probe array is not limited to the order shown in FIG. 3(A), and it may be arranged in any order on the condition that no interference occurs.

Explanation of Reference Numerals

[0032] 11 Probe array 11A 70-degree angled probe 11B 0-degree probe 11C 40-degree & tandem shared probe 11D 40-degree angled probe 12A~12F Transceiver circuit 13 Oscillation circuit 14 Signal processing unit 15 Vehicle speed sensor 16 Travel distance calculation circuit 17 Trigger signal generation circuit 18 Display unit 19 Storage unit

Claims

1. A rail flaw detector for a vehicle, which is mounted on a vehicle running on a rail, and a plurality of probes each having an ultrasonic vibrator for transmitting and receiving ultrasonic waves are arranged to contact the top surface of the rail to be inspected. Ultrasonic waves are transmitted from the ultrasonic vibrator at a predetermined pitch during vehicle running, and flaws inside the rail are detected based on the received signals of the probes. Among them, one of the plurality of probes is configured as a shared probe including one ultrasonic vibrator that transmits ultrasonic waves in the longitudinal direction of the rail at a predetermined angle set in the range of 35 degrees to 45 degrees with respect to the top surface of the rail and receives an echo, and one ultrasonic vibrator that is arranged at a position away from the ultrasonic vibrator, receives the echo of the ultrasonic waves transmitted from the ultrasonic vibrator, and detects flaws inside the rail by the tandem method.

2. The rail flaw detector for a vehicle according to claim 1, wherein the upper limit of the running speed of the vehicle is 70 km / h, and the predetermined pitch is set to 3 to 5 mm.

3. Among the plurality of probes, excluding the shared probe, the probes include an oblique probe that transmits and receives ultrasonic waves at the same angle in the direction opposite to the shared probe with respect to the plane orthogonal to the top surface of the rail, a pair of oblique probes having a larger transmission angle than the shared probe and the oblique probe, and a pair of probes that transmit and receive ultrasonic waves at different frequencies in the direction orthogonal to the top surface of the rail. The rail flaw detector for a vehicle according to claim 1 or 2.

Images