Probe holder and jig for defect detection

Abstract

To provide a probe holder and a flaw detecting jig capable of easily finding a flaw generated in a welded part by rotating a probe itself by a simple constitution.SOLUTION: A probe holder 1 includes a housing 10 in which an accommodation hole 10a having a circular shape when viewed from a side surface side of a rail R is formed, and a holding section 20 that is inserted into the accommodation hole 10a, rotates about a central shaft X of the accommodation hole 10a, and in which an insertion hole 20a into which a probe 30 is inserted is formed, and the probe 30 is fixed to the insertion hole 20a such that a transmission position or a reception position of ultrasonic waves is arranged at a position not overlapping the central shaft X.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a probe holder and a defect detection jig. [Background technology]

[0002] At railway construction sites, thermite welding is widely used as a method for joining rails together. For thermite welding, ultrasonic testing (ultrasonic flaw detection) is conducted to check for defects in the weld immediately after construction. Ultrasonic flaw detection tests check the reflected waves of transmitted ultrasonic waves to determine the presence and size of weld defects within the weld and evaluate its integrity.

[0003] For example, Patent Document 1 discloses an ultrasonic flaw detector that can determine whether or not non-metallic inclusions are present in an object to be measured, and can also analyze the shape of the non-metallic inclusions if they are present. The inner ring, which is the object to be inspected, is inspected for internal defects by transmitting ultrasonic waves from multiple probes to the inner ring. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-090245 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in the ultrasonic flaw detection device described in Patent Document 1, the inner ring is rotated by rotating a rotary table that supports the inner ring, and the inner ring is inspected for defects by moving multiple probes. However, this type of inspection method has the disadvantage of requiring a large-scale configuration that requires the provision of a rotary table.

[0006] Therefore, an object of the present invention is to provide a probe holder and a defect detection jig that can rotate the probe itself with a simple configuration, making it easier to find defects that have occurred inside a welded portion. [Means for solving the problem]

[0007] In response to the above-mentioned problems, the probe holder of the present invention is a probe holder for a probe that detects the presence or absence of defects in a welded portion by irradiating ultrasonic waves toward the welded portion that joins rails together, and is characterized in that it comprises a housing in which an accommodating hole that is circular when viewed from the side of the rail is formed, and a holding part that is inserted into the accommodating hole and rotates around the central axis of the accommodating hole and in which an insertion hole is formed into which the probe is inserted, and the probe is fixed in the insertion hole so that the transmitting position or receiving position of the ultrasonic waves is positioned at a position that does not overlap with the central axis.

[0008] Here, it is desirable that the housing has a first surface located on the rail side and a second surface located on the opposite side of the rail side, the holding portion is formed in a circular plate shape having a third surface located on the first surface side and a fourth surface located on the opposite side of the third surface, and the third surface is positioned in a recessed position on the opposite side of the rail than the first surface side.

[0009] The defect detection jig of the present invention preferably includes a pair of the above-described probe holders and a connecting portion that connects the pair of probe holders with the housings facing each other across the rail, and the connecting portion preferably has a pair of legs to which the probe holders are respectively attached and a beam portion that connects the upper portions of the legs. Furthermore, when the tip of the housing is in contact with the welded portion, the dimension of the housing from the position where the probe is inserted to the tip is preferably calculated based on the dimension of the width direction of the bottom of the rail.

[0010] It is also desirable that the positional relationship between the lower end surfaces of the legs and the insertion holes be set in accordance with the height of the bottom of the rail, and that the positional relationship between the lower surfaces of the beams and the insertion holes be set in accordance with the height of the head of the rail. [Effects of the Invention]

[0011] The probe holder of the present invention comprises a housing having a circular accommodation hole when viewed from the side of the rail, and a holding part having an insertion hole into which a probe is inserted, the holding part being inserted into the accommodation hole and rotating around the central axis of the accommodation hole, and the probe is fixed in the insertion hole so that the ultrasonic transmission position or reception position is positioned so as not to overlap with the central axis.

[0012] This allows the probe to rotate at an eccentric position relative to the central axis of the holder, ensuring a wide range of ultrasonic waves radiated from the probe in all directions. This makes it easier to find defects inside the rail by simply rotating the probe itself.

[0013] In particular, the third surface of the holder is recessed toward the opposite side of the rail than the first surface of the housing. Therefore, a recess is formed by the housing and the holder. Therefore, by filling the recess with a contact medium, it is possible to prevent a gap from occurring between the rail to be inspected and the probe.

[0014] The defect detection jig also includes a probe holder and a connecting portion that connects the pair of probe holders with their housings facing each other across the rail, and the connecting portion has a pair of legs to which the probe holders are respectively attached and a beam portion that connects the upper portions of the legs. This allows the defect detection jig to be placed on the rail with the pair of probes sandwiching the rail. Therefore, defects can be detected by irradiating ultrasonic waves using the probes that are placed at opposing positions on both sides of the rail in the width direction.

[0015] Furthermore, when the tip of the housing is in contact with the weld, the dimension from the position where the probe is inserted to the tip of the housing is calculated based on the width dimension of the bottom of the rail. By determining the approximate position where the probe is inserted in the housing in this way, it is possible to improve the accuracy of detecting defects that occur in the weld.

[0016] The positional relationship between the lower end surface of the leg and the insertion hole is set according to the height of the rail bottom, because it is determined taking into account the direction of the ultrasonic waves emitted from the probe, thereby improving the accuracy of detecting defects in the welded part at the bottom in the vertical direction.

[0017] The positional relationship between the underside of the beam of the defect detection jig and the insertion hole is set according to the height of the rail head. This is because the positional relationship is determined taking into consideration the direction of the ultrasonic waves emitted from the probe. This improves the accuracy of detecting defects in the welded part at the head in the vertical direction. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1(a) is a front view of a defect inspection jig according to a first embodiment, and FIG. 1(b) is a side view of the defect inspection jig according to the first embodiment. [Figure 2] FIG. 1(a) is a schematic front view of a probe holder according to a first embodiment, and FIG. 1(b) is a schematic cross-sectional view of the probe holder according to the first embodiment. [Figure 3] FIG. 2(a) is a schematic front view of the holding portion, and FIG. 2(b) is a schematic cross-sectional view of the holding portion. [Figure 4] 1A and 1B are diagrams showing a state in which a defect detection jig is installed on a rail, where FIG. 1A is a diagram seen from the longitudinal direction of the rail, and FIG. 1B is a diagram seen from the width direction of the rail. [Figure 5] (a) is a view from the width direction of the rail showing the process of detecting defects at the bottom using a probe, and (b) is a view from the longitudinal direction of the rail showing the process of detecting defects at the bottom using a probe. [Figure 6] 1A and 1B are diagrams for explaining the positional relationship between the range where ultrasonic waves can be emitted by the probe and the bottom, where FIG. 1A is a diagram viewed from the width direction of the rail, and FIG. 1B is a diagram viewed from the longitudinal direction of the rail. [Figure 7] FIG. 10 is a top view showing a state in which the probe has detected a defective portion. [Figure 8] FIG. 10 is a diagram showing a state in which the probe holder is filled with a contact medium. [Figure 9] FIG. 10 is a diagram showing the positional relationship between a defect inspection jig and a head according to a second embodiment. [Figure 10] 10A and 10B are views showing the process of detecting a defect in the head portion by a probe, as viewed from the width direction of the rail. [Figure 11] 10 is a diagram for explaining the positional relationship between the range in which ultrasound can be emitted by the probe and the head. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] (First embodiment) A first embodiment of the present invention will be described below with reference to the drawings. Fig. 1(a) is a front view of a defect detection jig 100 according to the first embodiment of the present invention, and Fig. 1(b) is a side view of the defect detection jig 100 according to the first embodiment.

[0020] The defect detection jig 100 comprises a main body 101 and a probe holder 1 provided on the outside of the main body 101. The main body 101 comprises a connecting portion 110 and a gripping portion 140 provided on the upper portion of the connecting portion 110. For ease of explanation, FIGS. 1(a) and 1(b) show the probe holder 1 with a probe 30 inserted therein.

[0021] The connecting portion 110 has a pair of legs 120 to which the probe holders 1 are respectively attached, and a beam portion 130 that connects the upper portions of the legs 120. Each leg 120 extends in the vertical direction and has a lower end surface 121 at its lower end. The lower end surface 121 is formed in a tapered shape that slopes upward as it approaches the other leg 120.

[0022] 1(a), the defect detection jig 100 has a pair of probe holders 1 on both sides in the width direction. Since the pair of probe holders 1 have similar shapes and functions, the following will describe one of the probe holders 1, and differences will be mentioned in each case.

[0023] Fig. 2(a) is a schematic front view of the probe holding device 1 according to the first embodiment, and Fig. 2(b) is a schematic cross-sectional view of the probe holding device 1 according to the first embodiment. Fig. 3(a) is a schematic front view of the holding portion 20, and Fig. 3(b) is a schematic cross-sectional view of the holding portion 20.

[0024] As shown in FIGS. 2(a) and 2(b), the probe holder 1 has a housing 10 and a holding part 20 that is inserted into the housing 10. The housing 10 is formed in a flat or rectangular parallelepiped shape and has an accommodating hole 10a that penetrates in the thickness direction. The accommodating hole 10a is formed in a circular shape when viewed from the front side (the side of the rail). The surface of the housing 10 facing the leg part 120 is a first surface 11, and the surface opposite the leg part 120 is a second surface 12.

[0025] The holding portion 20 is accommodated in the accommodation hole 10a. The holding portion 20 is inserted into the accommodation hole 10a and rotates around the central axis X of the accommodation hole 10a. The dimensions of the accommodation hole 10a may be determined appropriately depending on the dimensions of the holding portion 20 accommodated in the housing 10.

[0026] 3(a) and 3(b), the holding portion 20 is formed in a disk shape. The holding portion 20 is formed to a size that allows it to be accommodated in the accommodation hole 10a. The surface of the holding portion 20 facing the leg portion 120 is a third surface 23, and the surface opposite the leg portion 120 is a fourth surface 24.

[0027] An insertion hole 20a into which the probe 30 is inserted is formed in the holding portion 20. The insertion hole 20a is formed at a position that is eccentric with respect to the central axis X of the holding portion 20 in a plan view. In other words, the center of gravity of the insertion hole 20a does not coincide with the central axis X of the holding portion 20, and is formed at a position that is offset from the center of the holding portion 20 toward the peripheral edge of the holding portion 20.

[0028] As shown in FIG. 2(a), a probe 30 is inserted into the insertion hole 20a. The probe 30 has a generally rectangular shape in a plan view, with the longitudinal direction extending from a position overlapping the central axis X toward the periphery of the accommodation hole 10a. The probe 30 is provided with a transceiver unit 31 that has the function of transmitting or receiving ultrasonic waves. The transceiver unit 31 is provided in a position in the holding unit 20 that does not overlap with the central axis X. Specifically, the transceiver unit 31 is provided at a position spaced a predetermined distance from the end of the probe 30 on the insertion hole 20a side in the longitudinal direction.

[0029] 2(b), the holding unit 20 is provided with a plurality of bearings 21 for moving the probe 30 in the up / down and left / right directions (oscillating scanning). That is, by supporting the holding unit 20 via the bearings 21, which are spherical bodies arranged in a ring, the holding unit 20 can rotate smoothly, making it possible to easily perform oscillating scanning with the probe 30.

[0030] Fig. 4 is a diagram showing a state in which the defect detection jig 100 is installed on a rail R. Fig. 4(a) is a diagram seen from the longitudinal direction of the rail R, and Fig. 4(b) is a diagram seen from the width direction of the rail R (the direction perpendicular to the extension direction of the rail R).

[0031] 4(a), the defect detection jig 100 is arranged so as to cover the rail R. Specifically, the defect detection jig 100 is seated on the bottom R1 of the rail R with a gap between it and the head R2 of the rail R. The pair of housings 10 are arranged parallel to each other, facing each other with the rail R in between, so as to be in contact with the bottom R1 in the width direction.

[0032] The positional relationship between the lower end surfaces 121 of the legs 120 and the insertion holes 20a is set according to the height of the bottom portion R1 of the rail R. Specifically, the positioning in the up-down direction is determined by placing the lower end surfaces 121 on the bottom portion R1 of the rail R. Furthermore, the defect detection jig 100 is positioned in the width direction by sandwiching the bottom portion R1 of the rail R between the pair of housings 10.

[0033] One of the pair of probes 30 has a function of emitting ultrasonic waves, and the other has a function of receiving ultrasonic waves. As will be described later, when the probe 30 is used to detect the presence or absence of a defect in the head R2 of the rail R, the positional relationship between the lower surface of the beam portion 130 and the insertion hole 20a may be set according to the height of the head R2 of the rail R.

[0034] 4(b), the defect detection jig 100 is placed on the rail R with the housing 10 in contact with the welded portion W. The probe 30 is eccentric to the central axis X, and by rotating in the direction of the arrow in the figure, the probe 30 can irradiate ultrasonic waves onto the bottom R1 while changing its height in the vertical direction.

[0035] Fig. 5(a) is a diagram showing the process of detecting a defect portion D in the bottom portion R1 by the probe 30 as viewed from the width direction of the rail R, and Fig. 5(b) is a diagram showing the process of detecting a defect portion D in the bottom portion R1 by the probe 30 as viewed from the longitudinal direction of the rail R. In the following figures, for the sake of convenience of explanation, components other than the probe 30 and the rail R are omitted as appropriate.

[0036] The probe 30 is used to detect the presence or absence of defects in the welded portion W by irradiating ultrasonic waves toward the welded portion W that joins the rails R. The probe 30 can be moved along the longitudinal direction of the rail R.

[0037] A welded portion W is formed where the rails R are welded together, and a damaged portion (defective portion D) due to welding often occurs in the welded portion W. As shown in FIG. 5(b), this defective portion D tends to be formed above the bottom portion R1. Therefore, the probe 30 is moved so that ultrasonic waves can be irradiated onto the bottom portion R1. Note that welding can be performed by a thermite welding method, for example, but is not limited to this.

[0038] 5(b), the direction of the ultrasonic waves emitted from the probe 30 is diagonally upward. Therefore, the probe 30 is positioned below the defective portion D so that the ultrasonic waves emitted from the probe 30 can be easily irradiated onto the defective portion D. As the holder 20 rotates, the probe 30 rotates eccentrically and moves adjacent to the welded portion W, so that the defective portion D can be searched for while moving up and down.

[0039] 6A and 6B are diagrams for explaining the positional relationship between the range 50 where ultrasound can be emitted by the probe 30 and the bottom R1, with (a) being a view from the width direction of the rail R and (b) being a view from the longitudinal direction of the rail R. The probe 30 rotates around the central axis X in the direction of the double arrow, and the transmitting / receiving unit 31 is provided at a position on the probe 30 that does not overlap with the central axis X. In other words, the transmitting / receiving unit 31 rotates eccentrically with respect to the central axis X.

[0040] The irradiation range 50 of the ultrasonic waves emitted from the transmitter / receiver 31 is the shaded area as shown in FIG. 6(b). Specifically, the irradiation range 50 is the area excluding both sides of the bottom R1 in the width direction. In order to detect a defect D that has occurred in the bottom R1, the bottom R1 must first be the target of irradiation of ultrasonic waves by the transmitter / receiver 31. Specifically, at least a portion of the defect D must overlap with the irradiation range 50. Therefore, the housing 10 is positioned relative to the bottom R1 so that the area between the center 121a, which is the center of the bottom end surface 121, and the bottom center Ra, which is the center of the bottom R1 in the up-down direction, overlaps with the irradiation range 50.

[0041] 7 is a top view of the state in which the probe 30 has detected a defect D. Here, it is empirically recognized that the defect D tends to occur in the center of the weld W along the rail longitudinal direction. In other words, the distance from the defect D to the front end W1 or the rear end W2 of the weld W is approximately equal.

[0042] Furthermore, if the distance from the defective portion D in the welded portion W to the front end portion W1 or the rear end portion W2 in the direction along the longitudinal direction of the rail at the bottom R1 is P, the distance from the rear end portion W2 to the transmitter / receiver 31 is H, the distance from the welded portion W to the transmitter / receiver 31 of both probes 30 is a or b, and the bottom width at the bottom R1 is L, the sum of a and b is approximately equal to the bottom width L.

[0043] This is because the irradiation angle A of the ultrasound emitted from the probe 30 (transmitter / receiver 31) toward the defect part D and the reception angle B at which the ultrasound reflected by the defect part D is received are both 45 degrees, and the shape connecting the three points of the pair of probes 30 and the defect part D is a right-angled isosceles triangle.

[0044] If the sum of a and b is different from the bottom width L, there is a risk that the ultrasonic waves emitted from one probe 30 will be reflected by a location that is not the defective portion D, such as the front end W1 or the rear end W2, and be received by the other probe 30. In other words, there is a possibility that a location that is not the defective portion D will be erroneously detected as a defect.

[0045] On the other hand, if the sum of a and b matches the bottom width L, it can be assumed that the ultrasonic waves emitted from one probe 30 are reflected by the defect D and received by the other probe 30. This improves the accuracy of detecting the defect D.

[0046] When the tip 10b of the housing 10 is in contact with the welded portion W, the dimension from the position in the housing 10 where the probe 30 is inserted to the tip 10b is calculated based on the dimension in the width direction (bottom width L) of the bottom R1 of the rail R. In this way, by obtaining information about the bottom width L in advance and calculating the values ​​of a and b, which are approximately half the dimensions of the bottom width L, when the housing 10 is in contact with the defective portion D, it is possible to give the housing 10 a ruler function (distance measurement function).

[0047] 8 is a diagram showing a state in which the probe holder 1 is filled with a contact medium M. The housing 10 has a first surface 11 located on the rail side and a second surface 12 located on the opposite side from the rail side. The holder 20 has a third surface 23 located on the first surface 11 side and a fourth surface 24 located on the opposite side from the third surface 23.

[0048] When the holding part 20 is accommodated in the accommodation hole 10a, the third surface 23 is disposed in a position recessed toward the opposite side of the rail R from the first surface 11. Therefore, a recess C is formed in the probe holder 1 by the housing 10 and the holding part 20, and the recess C is filled with a contact medium M.

[0049] The couplant M is filled to prevent gaps from occurring between the probe 30 and the rail R to be inspected. In conventional handheld flaw detection, the probe 30 must be kept parallel while scanning, so the probe 30 is continuously moved while in contact with the rail R. As a result, the couplant M is scraped away by the scanning of the probe 30, which can impair the transmission of ultrasonic waves and reduce detection accuracy. To prevent this from happening, a recess C is formed in the probe holder 1. Note that the couplant M can be, for example, SONICOAT (registered trademark), but is not limited to this.

[0050] As described above, the probe holder 1 according to the first embodiment includes a housing 10 having a accommodating hole 10a formed therein that is circular when viewed from the side of the rail R, and a holder 20 having an insertion hole 20a formed therein into which the probe 30 is inserted and which is inserted into the accommodating hole 10a and rotates around the central axis X of the accommodating hole 10a, and the probe 30 is fixed in the insertion hole 20a so that the ultrasonic transmission position or reception position is positioned at a position that does not overlap with the central axis X.

[0051] As a result, the probe 30 rotates at a position eccentric to the central axis X of the holder 20, ensuring a wide range of ultrasonic waves radiated from the probe 30 in the vertical direction. In other words, the range of ultrasonic waves radiated can be widened compared to when the probe 30 is not eccentric. Therefore, by rotating the probe 30 itself with a simple configuration, defects occurring inside the rail R can be easily found.

[0052] In particular, the third surface 23 of the holding portion 20 is disposed at a position recessed toward the opposite side of the rail R from the first surface side of the housing 10. Therefore, a recess C is formed by the housing 10 and the holding portion 20. Therefore, by filling the recess C with a contact medium M, it is possible to prevent a gap from occurring between the rail R to be inspected and the probe 30.

[0053] The defect detection jig 100 also includes a probe holder 1 and a connecting portion 110 that connects the pair of probe holders 1 with the housings 10 facing each other across the rail R, and the connecting portion 110 has a pair of legs 120 to which the probe holders 1 are respectively attached, and a beam portion 130 that connects the upper portions of the legs 120. Therefore, the defect detection jig 100 can be placed on the rail R with the pair of probes 30 sandwiching the rail R. Therefore, defects can be detected by irradiating ultrasonic waves with the probes 30 that are placed at opposing positions on both sides of the rail R in the width direction.

[0054] Furthermore, when the tip 10b of the housing 10 is in contact with the welded portion W, the dimension from the position in the housing 10 where the probe 30 is inserted to the tip 10b is calculated based on the dimension in the width direction of the bottom R1 of the rail R. By determining the approximate position in the housing 10 where the probe 30 is inserted in this way, the accuracy of detecting a defect D occurring in the welded portion W can be improved.

[0055] Furthermore, the positional relationship between the lower end surface 121 of the leg 120 and the insertion hole 20a is set according to the height of the bottom R1 of the rail R. This is because it is determined taking into consideration the direction of the ultrasonic waves emitted from the probe 30. Therefore, it is possible to improve the accuracy of detecting defects D in the welded portion W that occur at the bottom R1 in the vertical direction.

[0056] (Second embodiment) Next, a defect detection jig 200 according to a second embodiment will be described with reference to Figs. 9 to 11. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. For convenience of description, illustration of some components may be omitted.

[0057] 9 is a diagram showing the positional relationship between the defect detection jig 200 and the head R2 when detecting a defect portion D in the head R2. The defect detection jig 200 is configured with a pair of legs 220 to which the probe holders 1 are respectively attached, and a connecting portion 210 having a beam portion 230 connecting the upper portions of the legs 220. As shown in FIG. 9, the beam portion 230 is disposed so as to be in contact with the head R2. That is, by placing the beam portion 230 on the head R2, the defect detection jig 200 is installed on the rail R and is positioned in the vertical direction.

[0058] 10 is a view showing the process of detecting a defect D in the head R2 using the probes 30, viewed from the width direction of the rail R. In the welded portion W, the defect D may occur not only in the bottom R1 but also in the head R2. Therefore, similar to the case of detecting a defect D occurring in the bottom R1, a pair of probes 30 inserted into the holders 20 (not shown) of the housing 10 may be moved along the longitudinal direction of the rail R, with the head R2 as the target.

[0059] 11 is a diagram illustrating the positional relationship between the head R2 and an irradiable range 60 of ultrasound by the probe 30. As in the case of irradiating the bottom R1, the range that the probe 30 can irradiate when irradiating the head R2 is also limited to a certain range in the vertical direction. In FIG. 11, the range indicated by diagonal lines is the irradiable range 60.

[0060] In order to detect the defective portion D that has occurred in the head R2, the head R2 needs to be included in the irradiation range 60 of the probe 30. Specifically, the housing 10 (see FIG. 9) is positioned relative to the head R2 so that the portion between the head center Rb, which is the central portion of the head R2 in the up-down direction, and the lower end 231, which is the lower end of the beam portion 230 (the dot portion in the drawing) overlaps with the irradiation range 60.

[0061] As described above, in the second embodiment, the positional relationship between the lower surface of the beam portion 230 of the defect detection jig 200 and the insertion hole 20a is set according to the height of the head portion R2 of the rail R. This is because the positional relationship is determined taking into consideration the direction of the ultrasonic waves emitted from the probe 30. Therefore, it is possible to improve the detection accuracy of the defect portion D in the weld portion W that occurs in the head portion R2 in the vertical direction.

[0062] Each embodiment of the present invention has been described in detail above with reference to the drawings, but the specific configuration is not limited to these embodiments, and design changes that do not deviate from the gist of the present invention are included in the present invention.

[0063] For example, in the above embodiment, a defect detection jig 100 was described in which a pair of probe holders 1 connected by a connecting portion 110 are arranged on both sides of the rail R, but this is not limited to this, and it is also possible to use only the probe holder 1 alone to perform ultrasonic flaw detection inspection using the probe 30.

[0064] Furthermore, in the first embodiment, when detecting a defect portion D occurring in the bottom portion R1, the range defined by the central portion 121a, which is the central portion of the lower end surface 121, and the bottom center Ra, which is the central portion of the bottom portion R1 in the vertical direction, is included in the irradiatable range 50, but this is not limited to this, and the probe 30 may be able to detect the defect portion D by including the bottom center Ra in the irradiatable range 50.

[0065] Furthermore, in the second embodiment, when detecting a defective portion D occurring in the head R2, the portion between the head center Rb, which is the central portion in the vertical direction of the head R2, and the lower end portion 231, which is the lower end of the beam portion 230, is included in the irradiatable range 60, but this is not limited to this, and the head center Rb may be included in the irradiatable range 60 so that the probe 30 can detect the defective portion D. [Explanation of symbols]

[0066] 1: Probe holder 10: Housing 10a: Receiving hole 10b: Tip 11: 1st page 12:Second side 20: Holding part 20a: Insertion hole 23: 3rd page 24:Side 4 30: Probe 100: Defect detection jig 101: Main body 110:Connection part 120: Legs 121: Bottom end surface 130: Beam part C: Concave D: Defective part M: Couplant R: Rail R1: Bottom R2: Head W: Welded part X: Central axis

Claims

1. A probe holder for a probe that detects the presence or absence of defects in a welded portion by irradiating ultrasonic waves toward the welded portion that joins rails together, a housing having a receiving hole formed therein, the receiving hole having a circular shape when viewed from the side of the rail; a holding portion that is inserted into the accommodation hole and rotates around a central axis of the accommodation hole, and that has an insertion hole into which the probe is inserted, The probe holder is characterized in that the probe is fixed in the insertion hole so that the ultrasonic wave transmission position or reception position is positioned at a position that does not overlap with the central axis.

2. the housing has a first surface positioned on the rail side and a second surface positioned on the opposite side from the rail side, the holding portion is formed in a disk shape having a third surface located on the first surface side and a fourth surface located on the opposite side to the third surface, The probe holder according to claim 1 , wherein the third surface is disposed at a position recessed from the first surface side toward the opposite side from the rail.

3. a pair of probe holders according to claim 1 or 2; a connecting portion that connects the pair of probe holders in a state where the housings face each other with the rail in between, The defect detection jig is characterized in that the connecting portion has a pair of legs to which the probe holders are respectively attached, and a beam portion connecting the upper portions of the legs.

4. A defect detection jig as described in claim 3, characterized in that when the tip of the casing is in contact with the welded portion, the dimension from the position where the probe is inserted in the casing to the tip is calculated based on the width dimension of the bottom of the rail.

5. 4. The defect detection jig according to claim 3, wherein the positional relationship between the lower end surfaces of the legs and the insertion holes is set in accordance with the height of the bottom of the rail.

6. 4. The defect detection jig according to claim 3, wherein the positional relationship between the lower surface of the beam portion and the insertion hole is set in accordance with the height of the head portion of the rail.

Images