Cable fixing part inspection device and inspection method

Abstract

To provide an inspection device and an inspection method for a cable fixing portion, that can inspect the presence or absence of damage to strands in the cable fixing portion.SOLUTION: An inspection device according to this embodiment includes: a probe 3 having an excitation coil 32 at one end of a substantially U-shaped yoke 31 and a detection coil 33 at the other end of the yoke 31; a support portion 4 for supporting the probe 3 so that the excitation coil 32 is positioned radially outside a cable 1 and the detection coil 33 is positioned radially inside the cable 1; an operation portion 5 for inserting the probe 3 and the support portion 4 into a cylindrical body 21; and a damper 6 arranged at a tip of the probe 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inspection device and an inspection method for a cable fixing portion, and more particularly to an inspection device and an inspection method for a cable fixing portion that can inspect for damage at the fixing portion of a cable in which a plurality of wires are bundled and covered. [Background technology]

[0002] Cables used in structures such as suspension bridges and cable-stayed bridges are made by bundling multiple steel wires and covering them with a resin layer such as an elastomer sheet. Such cables are exposed to wind and rain, and if the resin layer on the surface is damaged, water can seep inside, causing the wires to corrode over long periods of use.

[0003] For example, Patent Document 1 discloses an inspection device that includes a pair of excitation coils that magnetize an inspection target portion of a wire, and a detection coil that detects the amount of magnetic flux passing through the inspection target portion of the wire magnetized by the excitation coils. This invention makes it possible to inspect the wire for corrosion without removing the resin layer that covers the wire. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-233849 Summary of the Invention [Problem to be solved by the invention]

[0005] The lower end of the cable is often fixed (anchored) in a steel tube placed on the support of the building. In addition, water that seeps into the cable tends to move downward and accumulate.

[0006] However, the inspection device described in Patent Document 1 cannot be inserted into the steel pipe that constitutes the cable anchorage part, which makes it difficult to inspect the wires for damage such as corrosion.

[0007] The present invention was devised in view of the above problems, and aims to provide an inspection device and inspection method for a cable fixing portion that can inspect whether or not there is damage to the wires at the cable fixing portion. [Means for solving the problem]

[0008] According to the present invention, an inspection device for a cable fixing portion is provided in which the end of a cable made of a bundle of wires and covered with a resin layer is inserted into a cylindrical body and fixed to a building, and the device has an excitation coil at one end of a substantially U-shaped yoke and a detection coil at the other end of the yoke. Rup The present invention provides an inspection device for a cable fixing portion, comprising: a probe; a support part that supports the probe so that the excitation coil is positioned radially outside the cable and the detection coil is positioned radially inside the cable; and an operating part that inserts the probe and the support part into the interior of the cylindrical body, wherein the probe and the support part are configured to be sized so that they can be inserted into the cylindrical body.

[0009] A plurality of the yokes may be arranged in the circumferential direction of the cable.

[0010] The yoke may be fixed to the support at a position intermediate between the excitation coil and the detection coil.

[0011] The support portion may be formed of an annular body that can be divided into a plurality of parts in the circumferential direction.

[0012] The probe may have a damper disposed at the tip.

[0013] According to the present invention, there is also provided a method for inspecting a cable anchorage portion in which the end of a cable made of a bundle of wires and covered with a resin layer is inserted into a cylindrical body and fixed to a building, the method comprising the steps of: providing a substantially U-shaped yoke having an excitation coil at one end and a detection coil at the other end of the yoke; Rup Robe the excitation coil is inserted into the cylindrical body and supported so that the excitation coil is positioned radially outside the cable and the detection coil is positioned radially inside the cable; There is provided a method for inspecting a cable fixing portion, characterized in that the fixing portion of the cable is inspected by exciting the wire in the axial direction with the probe.

[0014] The inspection method may include outputting a voltage signal according to the size of the magnetized region of the magnetized wire from the detection coil, and detecting damage to the wire based on a change in the output voltage signal. [Effects of the Invention]

[0015] According to the above-described cable fixing portion inspection device and inspection method of the present invention, the probe that excites the wire can be inserted into a cylindrical body, making it possible to detect whether or not the wire at the cable fixing portion is damaged. [Brief explanation of the drawings]

[0016] [Figure 1] 10 is a cross-sectional view showing an inspection state using a cable fixing portion inspection device according to an embodiment. FIG. [Figure 2] 2(a) and 2(b) are enlarged views of the probe shown in FIG. 1, where (a) is a front view excluding the damper, and (b) is a cross-sectional view taken along line BB in FIG. 2(a). [Figure 3] 1A and 1B are diagrams showing the procedure for inserting a probe, in which (a) shows the initial state and (b) shows the inserted state. [Figure 4] FIG. 2 is a diagram illustrating the overall configuration of the inspection device shown in FIG. [Figure 5] 2A and 2B are conceptual diagrams showing an inspection method using the inspection device shown in FIG. 1, where (a) shows a case where the strand is not damaged and (b) shows a case where the strand is damaged. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to Fig. 1 to Fig. 5(b). Fig. 1 is a cross-sectional view showing an inspection state using an inspection device for a cable anchorage part according to one embodiment. Fig. 2 is an enlarged view of the probe shown in Fig. 1, where (a) is a front view excluding the damper, and (b) is a cross-sectional view taken along line BB in Fig. 2(a).

[0018] The cable 1 shown in Fig. 1 is made by bundling a number of steel wires 11 and covering them with a resin layer. As an example, the cable 1 is shown as being used in a cable-stayed bridge. The lower end of the cable 1 is fixed (anchored) to a bridge girder 2, for example.

[0019] The anchoring portion 2a of the cable 1 includes, for example, a cylindrical body 21 that is placed on the bridge girder 2 and through which the cable 1 is inserted, a bearing plate 22 that receives the tension of the cable 1, a socket 23 that covers the end of the cable 1, and a washer 24 that is placed between the bearing plate 22 and the socket 23. The cylindrical body 21 is, for example, a steel pipe. The socket 23 is filled with resin or the like.

[0020] The inspection device according to this embodiment has an excitation coil 32 at one end of a substantially U-shaped yoke 31 and a detection coil 33 at the other end of the yoke 31. Rup The probe 3 is provided with a probe 3, a support part 4 that supports the probe 3 so that the excitation coil 32 is positioned radially outside the cable 1 and the detection coil 33 is positioned radially inside the cable 1, an operating part 5 that inserts the probe 3 and the support part 4 into the inside of the cylindrical body 21, and a damper 6 that is arranged at the tip of the probe 3.

[0021] The yoke 31 is a yoke that constitutes a magnetic circuit. As shown in Figures 2(A) and 2(b), the yoke 31 has a generally U-shape overall, and for example, the thickness of the portion around which the excitation coil 32 is wound is formed to be thicker than the thickness of the portion around which the detection coil 33 is wound. In other words, the yoke 31 has a U-shape.

[0022] The support part 4 is a member that supports the probe 3 so that it can be inserted from above the cylindrical body 21. The support part 4 is formed, for example, of an annular body that can be divided into multiple pieces in the circumferential direction. FIG. 2(a) illustrates the case where the support part 4 is divided into two pieces, a first annular body 41 and a second annular body 42. The first annular body 41 and the second annular body 42 are configured so that they can be connected to each other in an annular shape by a connecting member 43 that is made of a plate material and a fastener.

[0023] The outer shape of the support part 4 is configured to a size that allows it to be inserted into the cylindrical body 21. For example, if the support part 4 has an annular shape, the outer diameter of the support part 4 is formed to be smaller than the inner diameter of the cylindrical body 21. Note that the outer shape of the support part 4 is not limited to annular, as long as it can be inserted into the cylindrical body 21.

[0024] As shown in Fig. 2(a), the yoke 31 is fixed to the support part 4 so that the detection coil 33 is positioned close to the cable 1. The support part 4 is located on the opposite side of the open end of the yoke 31, and the yoke 31 is fixed to the support part 4 at the intermediate part between the excitation coil 32 and the detection coil 33. The yoke 31 is fixed to the support part 4 by a fixing means 34 such as a cable tie. Note that the fixing means 34 is not limited to the configuration shown in the figure.

[0025] 2(a), multiple yokes 31 constituting the probes 3 are arranged in the circumferential direction of the cable 1. In this embodiment, three yokes 31 are fixed to each of the first annular body 41 and the second annular body 42 so that six probes 3 are arranged at equal intervals in the circumferential direction of the cable 1. Note that the number and arrangement of the probes 3 are not limited to the configuration shown in the figure, and depending on conditions such as the thickness of the cable 1, the number of probes 3 may be one or may be any number other than six.

[0026] As shown in the figure, the yoke 31 is arranged so as not to protrude from the outer shape of the support part 4. That is, the probe 3 according to this embodiment is configured to have a size that allows it to be inserted into the cylindrical body 21.

[0027] When multiple probes 3 are arranged in the circumferential direction, the probes 3 may be connected in series or in parallel. When the probes 3 are connected in series, the output of the probes 3 can be increased. When the probes 3 are connected in parallel, the position of the probe 3 at which the signal changes can be monitored to identify the location of the damaged portion of the cable 1 (wires 11).

[0028] The operating unit 5 is a member that inserts the probe 3 into the nozzle at the back of the cylindrical body 21. The operating unit 5 is, for example, a bar-shaped rod fixed to the support unit 4. The operating unit 5 only needs to be able to move the probe 3 along the axial direction of the cable 1. For example, if a sliding bearing or a rolling element is arranged inside the support unit 4 or if the probe 3 can be moved downward by its own weight, the operating unit 5 may be made of a wire, rope, or the like.

[0029] The damper 6 is a buffer member that protects the tip of the probe 3. The damper 6 is, for example, an elastic body configured to a size that allows it to be inserted into the cylindrical body 21. The damper 6 may be fixed to the tip of the yoke 31, or may be fixed to the support part 4. Since it is difficult to visually check the inside when inserting the probe 3 into the cylindrical body 21, by arranging the damper 6, the probe 3 can be easily inserted into the cylindrical body 21 and landed on the bottom.

[0030] Furthermore, by adjusting the thickness of the damper 6 in the cable axial direction, the distance from the bottom of the cylindrical body 21 can be adjusted, and the probe 3 can be positioned according to the location of the cable 1 that is to be inspected. For ease of explanation, the damper 6 is not shown in Figure 2(a).

[0031] 3A and 3B are diagrams showing the procedure for inserting the probe, with (a) showing the initial state and (b) showing the inserted state. As shown in Fig. 3A, during normal use of the cable 1, a cover 25 is disposed and sealed at the upper end of the cylindrical body 21. Although not shown, a sealing member may be disposed in the gap between the upper part of the cylindrical body 21 and the cover 25.

[0032] When inspecting cable 1, as shown in Figure 3(b), cover 25 is removed, and if there is a sealing member, the sealing member is removed to open the top of cylindrical body 21. Next, support unit 4 is placed along cable 1 and connected, probe 3 is placed on cable 1, and operating unit 5 is connected to support unit 4. Thereafter, operating unit 5 is moved along the axial direction of cable 1 to insert probe 3 to the bottom of cylindrical body 21.

[0033] Next, the overall configuration diagram and inspection method of the inspection device shown in Fig. 1 will be described with reference to Figs. 4 to 5(b). Here, Fig. 4 is an overall configuration diagram of the inspection device shown in Fig. 1. Fig. 5 is a conceptual diagram showing an inspection method using the inspection device shown in Fig. 1, where (a) shows a case where there is no damage to the wire and (b) shows a case where there is damage to the wire. For ease of explanation, in Figs. 5(a) and 5(b), the operation unit 5 and damper 6 are omitted and the configuration of the fixing unit 2a is simplified.

[0034] As shown in Figure 4, the cable fixing portion inspection device includes, for example, a probe 3 inserted into a cylindrical body 21, a power supply 7 connected to an excitation coil 32 of the probe 3, an A / D converter 8 connected to a detection coil 33 of the probe 3, and a computing device 9 that processes signals from the A / D converter 8.

[0035] The power supply 7 is a device that applies a current to the excitation coil 32. The power supply 7 may be a DC power supply or an AC power supply, and may include a device such as an amplifier. Furthermore, if the power supply 7 is a DC power supply, it may include a current breaker.

[0036] The A / D converter 8 is a device that converts an analog signal from the detection coil 33 into a digital signal. An amplifier that amplifies the detection signal from the detection coil 33 may be disposed upstream of the A / D converter 8.

[0037] The arithmetic unit 9 includes, for example, a signal processor 91 that processes the voltage signal detected by the detection coil 33, a signal display unit 92 that displays the detected signal, a detector / determiner 93 that compares the detection signal with a calibration curve obtained in advance to determine whether or not damage has occurred, and a signal storage unit 94 that stores the detection signal.

[0038] The arithmetic unit 9 is configured by, for example, a personal computer. The signal processor 91 performs processes such as measuring AC voltage values ​​and reading the voltage intensity of the applied frequency. The signal display unit 92 is, for example, a display or monitor. The detector / determiner 93 performs predetermined processes based on a predetermined program stored in the arithmetic unit 9. The signal storage unit 94 is, for example, a storage device such as an HDD or SSD.

[0039] The method for inspecting a cable anchorage according to this embodiment is a method for inspecting a cable anchorage in which the end of a cable 1, which is made by bundling a plurality of wires 11 and covering them with a resin layer, is inserted into a cylindrical body 21 and fixed to a building. The method comprises the steps of: (1) detecting a detection coil 33 at the other end of a substantially U-shaped yoke 31; Rup This is a method of inspecting the fixed portion 2 a of the cable 1 by inserting the probe 3 into the cylindrical body 21 and exciting the wires 11 in the axial direction with the probe 3 .

[0040] As shown in Figure 3(b), the probe 3 is inserted into the cylindrical body 21, and as shown in Figure 1, the probe 3 is placed at the bottom of the cylindrical body 21, and then a current is applied to the excitation coil 32 by the power supply 7 to generate a magnetic field.

[0041] The magnetic field generated by the excitation coil 32 is transmitted to the detection coil 33 via the yoke 31, and as shown in Fig. 5(a), a magnetic field is generated from the tip of the detection coil 33. The magnetic field generated from the detection coil 33 excites the wires 11 of the cable 1 in the axial direction.

[0042] As shown in Figure 5(a), if the wire 11 does not suffer from damage such as cross-sectional defects or breaks, the magnetic field has an effect far in the axial direction, forming a large magnetic circuit, the magnetized region M is evaluated as large, and the response (voltage signal) of the detection coil 33 becomes large.

[0043] On the other hand, as shown in Figure 5(b), if damage D occurs in the wire 11, the magnetic field does not reach far in the axial direction, the magnetic circuit is interrupted, the magnetized region M is evaluated as small, and the response (voltage signal) of the detection coil 33 becomes small.

[0044] Therefore, by inspecting a cable 1 with no damage to the wires 11 using the inspection device described above and obtaining a voltage signal (calibration curve) in a normal state in advance, damage to the wires 11 can be detected and determined by monitoring changes in the voltage signal output by the detection coil 33 during inspections such as maintenance.

[0045] That is, in the inspection method according to this embodiment, a voltage signal corresponding to the size of the magnetized region M of the magnetized wire 11 is output by the detection coil 33, and a change in the output voltage signal is used to detect damage to the wire 11. In this embodiment, damage detection is automated by the detector / determiner 93, but the presence or absence of damage may also be determined visually by an operator.

[0046] According to the inspection device and inspection method for the cable anchorage part of the present embodiment described above, the probe 3 that excites the wires 11 is configured to be insertable into the cylindrical body 21, making it possible to detect the presence or absence of damage due to corrosion of the wires 11 at the anchorage part 2a of the cable 1. Furthermore, according to the present embodiment, non-destructive inspection (detection of breaks and reductions in cross-sectional area) of the wires 11 that make up the cable 1 can be performed without opening the socket 23 of the anchorage part 2a.

[0047] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the spirit of the present invention, such as the possibility of using it to inspect cable anchorages used in structures other than cable-stayed bridges. [Explanation of symbols]

[0048] 1 cable 2 Bridge girders 2a Fixing part 3 Probe 4 Support part 5 Control section 6 Damper 7 Power 8 A / D converter 9 Arithmetic unit 11 Wire 21 Cylinder 22 Bearing plate 23 Socket 24 Washer 25 Cover 31 York 32 Excitation coil 33 Detection coil 34 Fixing means 41 First ring body 42 Secondary ring body 43 Connecting member 91 Signal processor 92 Signal indicator 93 Detector / Judger 94 Signal Preserver

Claims

1. An inspection device for a cable fixing portion in which an end of a cable made by bundling a plurality of wires and covering it with a resin layer is inserted into a cylindrical body and fixed to a building, a probe having an excitation coil at one end of a substantially U-shaped yoke and a detection coil at the other end of the yoke; a support portion that supports the probe so that the excitation coil is located radially outside the cable and the detection coil is located radially inside the cable; an operation unit for inserting the probe and the support unit into the cylindrical body, The probe and the support part are configured to have a size that allows them to be inserted into the cylindrical body. A cable fixing part inspection device characterized by the above.

2. The cable fixing portion inspection device according to claim 1 , wherein a plurality of the yokes are arranged in a circumferential direction of the cable.

3. 2. The cable fixing portion inspection device according to claim 1, wherein the yoke is fixed to the support portion at a middle portion between the excitation coil and the detection coil.

4. 2. The cable anchoring portion inspection device according to claim 1, wherein the support portion is formed of an annular body that can be divided into a plurality of portions in the circumferential direction.

5. The cable anchorage inspection device according to claim 1 , wherein the probe has a damper disposed at a tip thereof.

6. A method for inspecting a cable anchorage in which an end of a cable made by bundling a plurality of wires and covering it with a resin layer is inserted into a cylindrical body and fixed to a building, comprising the steps of: a probe having an excitation coil at one end of a substantially U-shaped yoke and a detection coil at the other end of the yoke, the probe being inserted into and supported by the cylindrical body so that the excitation coil is positioned radially outside the cable and the detection coil is positioned radially inside the cable; The probe is used to excite the wire in the axial direction to inspect the anchoring portion of the cable. A method for inspecting a cable fixing portion, comprising:

7. 7. The cable fixing portion inspection method according to claim 6, wherein a voltage signal corresponding to the size of the magnetized region of the wire is output by the detection coil, and damage to the wire is detected based on a change in the output voltage signal.

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