JP7441467B2 - Eddy current flaw detection probe - Google Patents

Description

The present invention relates to an eddy current flaw detection probe.

Eddy current testing is one of the inspection techniques for detecting cracks in conductive objects (specifically, steel plates, piping, etc.). In eddy current flaw detection, an eddy current flaw detection probe having an excitation coil and a detection coil is brought into contact with the surface of a test object. Then, an exciting current is passed through the exciting coil to generate a magnetic field, thereby inducing eddy currents in the subject. If there are cracks or cracks in the object, the eddy current changes, so changes in the impedance of the detection coil due to changes in the eddy current are detected. This allows cracks and cracks in the object to be detected to be detected.

BACKGROUND ART Eddy current flaw detection probes (multi-coil probes) are known that include a flexible substrate and a large number of coils arranged on the substrate (for example, see Patent Document 1). By using this eddy current flaw detection probe, even if the surface of the test object is a curved surface, the substrate of the eddy current flaw detection probe can be brought into close contact with the surface of the test object by deforming the substrate and the like. Then, by scanning (moving) the eddy current flaw detection probe along the surface of the object and switching the combination of the excitation coil and the detection coil among the many coils, it is possible to perform a wide range of inspections.

Japanese Patent Application Publication No. 2018-066671

However, the conventional technology has room for improvement as described below. In conventional eddy current flaw detection probes, the lead wire of the coil is directly connected, for example, to printed wiring on a board. Therefore, if the shape of the substrate changes due to the frictional force on the surface of the object during scanning with the eddy current flaw detection probe, tension will be generated in the lead wire of the coil. Therefore, there was room for improvement in terms of strength and durability.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an eddy current flaw detection probe that can improve strength and durability.

To achieve the above object, the present invention provides an eddy current flaw detection probe including a flexible substrate and a plurality of coil sets disposed on the substrate, each coil set being , a coil adhered to the surface of the substrate; an electrode block on one side adhered to the surface of the substrate and connected to a lead wire on the winding start side of the coil; and a coil adhered to the surface of the substrate; an electrode block on the other side connected to the lead wire at the end of the winding, and a non-conductive pedestal that holds the coil, the electrode block on the one side, and the electrode block on the other side so that they do not move relative to each other. The pedestal has an insertion hole into which the coil is inserted, a fitting groove on one side that fits with the electrode block on the one side, and a fitting groove on the other side that fits with the electrode block on the other side. and has .

According to the present invention, strength and durability can be improved.

1 is a top view showing the structure of an eddy current flaw detection probe according to a first embodiment of the present invention. 2 is a sectional view taken along section II-II in FIG. 1. FIG. FIG. 2 is a schematic diagram showing a deformed state of the eddy current flaw detection probe according to the first embodiment of the present invention, and a cross-sectional view taken along section BB. FIG. 2 is a partially enlarged top view of part IV of FIG. 1, showing the structure of the coil set in the first embodiment of the present invention. FIG. 5 is a sectional view taken along section VV in FIG. 4; It is a perspective view showing the structure of a coil set in a 1st embodiment of the present invention. FIG. 3 is a perspective view showing a peripheral structure of a coil in a comparative example. FIG. 3 is a diagram for explaining the range in which each coil set contacts the substrate in the first embodiment of the present invention. FIG. 7 is a partially enlarged top view showing the structure of a coil set in a second embodiment of the present invention. 10 is a sectional view taken along section XX in FIG. 9. FIG.

A first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a top view showing the structure of the eddy current flaw detection probe in this embodiment, and FIG. 2 is a sectional view taken along section II-II in FIG. FIG. 3(a) is a schematic diagram showing a deformed state of the eddy current flaw detection probe in this embodiment, and FIG. 3(b) is a sectional view taken along section BB in FIG. 3(a). Although FIG. 2 shows a cover, FIGS. 1, 3(a), and 3(b) omit illustration of the cover. FIG. 4 is a partially enlarged top view of part IV of FIG. 1, showing the structure of the coil set in this embodiment. FIG. 5 is a sectional view taken along section VV in FIG. FIG. 6 is a perspective view showing the structure of the coil set in this embodiment.

The eddy current flaw detection probe 1 of this embodiment includes a flexible rectangular substrate 2, a plurality of coil sets 3 arranged on the substrate 2, and a flexible rectangular substrate 2 that covers the substrate 2 and the plurality of coil sets 3. A cover 4 having a.

For example, as shown in FIGS. 3(a) and 3(b), even if the surface 101 of the welded part of the pipe 100 to be inspected is a curved surface, the substrate 2 etc. will deform in its longitudinal direction (Y direction). By doing so, it is possible to bring the substrate 2 of the eddy current flaw detection probe 1 into close contact with the surface 101 of the welded portion of the piping 100. Then, while scanning (moving) the eddy current flaw detection probe 1 in the lateral direction (X direction) of the substrate 2, by switching the combination of the excitation coil and the detection coil among the plurality of coils 5, which will be described later, a wide range of inspection can be performed. It is possible to do this.

The plurality of coil sets 3 are arranged in a staggered or grid pattern on the substrate 2, and the number of coil sets 3 in the longitudinal direction of the substrate 2 is larger than the number of coil sets 3 in the longitudinal direction of the substrate 2 (for example, 2 pieces). (for example, around 10) is increasing. Each coil set 3 includes a coil 5, a magnetic core 6, electrode blocks 7A, 7B, and a pedestal 8.

The magnetic core 6 is made of a magnetic material such as ferrite and has a cylindrical shape, and is bonded to the surface of the substrate 2. The outer diameter of the magnetic core 6 is slightly smaller than the inner diameter of the coil 5, and the height of the magnetic core 6 is approximately the same as the height of the coil 5. The coil 5 is arranged on the outer peripheral side of the magnetic core 6 and is bonded to the surface of the substrate 2. The coil 5 is formed into a cylindrical shape by winding a thin wire, and has a lead wire 9A on the winding start side and a lead wire 9B on the winding end side. The lead wires 9A and 9B are drawn out from above the coil 5.

The board 2 is provided with a signal line 10A and a ground line 10B as printed wiring. The electrode block 7A has a lower end bonded to the surface of the substrate 2 and connected to the signal line 10A by, for example, soldering, and an upper end connected to the lead line 9A. The lower end of the electrode block 7B is bonded to the surface of the substrate 2 and connected to the ground wire 10B by, for example, soldering, and the upper end is connected to the lead wire 9B. The signal line 10A and the ground line 10B of the board 2 are connected to a cable 12 via an intermediate connector 11.

The cable 12 is provided with an external connector 13 at its tip, and is connected to an eddy current flaw detection device (not shown) via the external connector 13. The eddy current flaw detection device performs control to switch the combination of an excitation coil and a detection coil among the plurality of coils 5, and acquires a change in impedance of the detection coil as a detection signal.

The electrode blocks 7A and 7B are made of a conductive material such as copper, and are arranged so as to be spaced apart from each other in the lateral direction (X direction) of the substrate 2. The electrode block 7A includes a vertical plate portion 14A extending in a direction rising from the surface of the substrate 2, and a vertical plate portion 14A extending in a direction along the surface of the substrate 2 from the base end side of the vertical plate portion 14A and bonded to the surface of the substrate 2. It is composed of a horizontal plate part 15A (first horizontal plate part) and a horizontal plate part 16A (second horizontal plate part) extending in the direction along the surface of the substrate 2 from the tip side of the vertical plate part 14A. The cross section is U-shaped. The depth dimension D of the electrode block 7A in the longitudinal direction (Y direction) of the substrate 2 is smaller than or the same as the outer diameter dimension φ of the coil 5 (see FIG. 8(a) described later). The height of the electrode block 7A is smaller than that of the coil 5.

Similarly, the electrode block 7B includes a vertical plate portion 14B that extends in a direction rising from the surface of the substrate 2, and a vertical plate portion 14B that extends in a direction along the surface of the substrate 2 from the base end side of the vertical plate portion 14B, and a vertical plate portion 14B that extends in a direction along the surface of the substrate 2. a horizontal plate portion 15B (first horizontal plate portion) bonded to the horizontal plate portion 15B (first horizontal plate portion); and a horizontal plate portion 16B (second horizontal plate portion) extending in the direction along the surface of the substrate 2 from the tip side of the vertical plate portion 14B. The cross section is U-shaped. The depth dimension D of the electrode block 7B in the longitudinal direction of the substrate 2 is smaller than or the same as the outer diameter dimension φ of the coil 5 (see FIG. 8(a) described later). The height of the electrode block 7B is smaller than that of the coil 5.

The pedestal 8 is made of a non-conductive material such as resin and is formed into a substantially rectangular parallelepiped shape. The width dimension of the pedestal 8 in the lateral direction of the substrate 2 and the depth dimension of the pedestal 8 in the longitudinal direction of the substrate 2 are larger than the outer dimension of the coil 5. An insertion hole (through hole) 17 into which the coil 5 is inserted is formed in the center of the pedestal 8 . The diameter of the insertion hole 17 of the base 8 is slightly larger than the outer diameter φ of the coil 5.

The pedestal 8 has a fitting groove 18A that is formed on one side of the substrate 2 in the lateral direction and fits with the electrode block 7A, and a fitting groove 18A that is formed on the other side of the substrate 2 in the lateral direction and fits with the electrode block 7B. It has a fitting groove 18B. The fitting groove 18A of the pedestal 8 does not fit with the horizontal plate part 15A of the electrode block 7A, but fits with the vertical plate part 14A and the horizontal plate part 16A. The fitting groove 18B of the pedestal 8 does not fit with the horizontal plate part 15B of the electrode block 7B, but fits with the vertical plate part 14B and the horizontal plate part 16B. Thereby, the pedestal 8 is arranged so as not to come into contact with the substrate 2. The depth dimension of the fitting groove 18A of the pedestal 8 in the longitudinal direction of the substrate 2 is slightly larger than the depth dimension of the electrode block 7A. The depth dimension of the fitting groove 18B of the pedestal 8 in the longitudinal direction of the substrate 2 is slightly larger than the depth dimension of the electrode block 7B. The height of the pedestal 8 is smaller than the height of the electrode blocks 7A and 7B.

Next, the effects of this embodiment will be explained using a comparative example. FIG. 7 is a perspective view showing a peripheral structure of a coil in a comparative example.

The eddy current flaw detection probe of the comparative example includes a flexible substrate 2 and a plurality of coils 5 arranged on the substrate 2, but does not include the electrode blocks 7A, 7B and the pedestal 8. That is, the lead wire 9A of the coil 5 is drawn out from above the coil 5 and directly connected to the signal line 10A of the board 2. Further, the lead wire 9B of the coil 5 is drawn out from the upper side of the coil 5 and directly connected to the ground wire 10B of the board 2. Therefore, if the shape of the substrate 2 changes due to the frictional force on the surface of the object during scanning with the eddy current flaw detection probe, tension is generated in the lead wires 9A and 9B of the coil 5. Therefore, the strength and durability of the probe are reduced.

On the other hand, in the eddy current flaw detection probe 1 of this embodiment, the electrode block 7A is interposed between the lead wire 9A of the coil 5 and the signal wire 10A of the board 2, and the electrode block 7A is interposed between the lead wire 9B of the coil 5 and the ground wire 10B of the board 2. Electrode block 7B is interposed between them, and coil 5, electrode block 7A, and electrode block 7B are held by pedestal 8 so as not to move relative to each other. Therefore, when the shape of the substrate 2 changes, although force acts on the electrode blocks 7A, 7B, etc., no tension is generated on the lead lines 9A, 9B. Therefore, the strength and durability of the probe can be improved.

Further, in the eddy current flaw detection probe 1 of this embodiment, the pedestal 8 is not in contact with the substrate 2. The electrode blocks 7A and 7B are arranged so as to be spaced apart from each other in the transverse direction (X direction) of the substrate 2, and the depth dimension D in the longitudinal direction (Y direction) of the substrate 2 is larger than the outer diameter dimension φ of the coil 5. small. Thereby, as shown in FIG. 8(a), the range in which each coil set 3 contacts the substrate 2 in the longitudinal direction of the substrate 2 becomes the outer diameter dimension φ of the coil 5. Therefore, the flexibility of the substrate 2 in the longitudinal direction can be maintained without being affected by the electrode blocks 7A, 7B and the pedestal 8.

Further, as shown in FIG. 8(b), the range in which each coil set 3 contacts the substrate 2 in the transverse direction of the substrate 2 is determined by the width dimension of the electrode block 7A, the width dimension of the electrode block 7B, and the width dimension of the electrode block 7A. , 7B, which can be made larger than the outer diameter φ of the coil 5. Therefore, the scanning stability of the probe can be improved compared to the case where the electrode blocks 7A, 7B and the pedestal 8 are not provided. As a result, for example, even if the scanning speed of the probe is increased when there is rust or roughness on the surface of the object, noise caused by lift-off can be suppressed.

A second embodiment of the present invention will be described. In addition, in this embodiment, parts equivalent to those in the first embodiment are given the same reference numerals, and description thereof will be omitted as appropriate.

FIG. 9 is a partially enlarged top view showing the structure of the coil set in this embodiment. FIG. 10 is a sectional view taken along section XX in FIG.

In this embodiment, the electrode block 7A includes a vertical plate portion 14A that extends in a direction rising from the surface of the substrate 2, and a vertical plate portion 14A that extends in a direction along the surface of the substrate 2 from the base end side of the vertical plate portion 14A. and a horizontal plate portion 15A bonded to the surface thereof, and has an L-shaped cross section. Similarly, the electrode block 7B includes a vertical plate portion 14B that extends in a direction rising from the surface of the substrate 2, and a vertical plate portion 14B that extends in a direction along the surface of the substrate 2 from the base end side of the vertical plate portion 14B, and a vertical plate portion 14B that extends in a direction along the surface of the substrate 2. The horizontal plate portion 15B is bonded to the horizontal plate portion 15B, and has an L-shaped cross section.

The fitting groove 18A of the pedestal 8 does not fit with the horizontal plate part 15A of the electrode block 7A, but fits with the vertical plate part 14A. The fitting groove 18B of the pedestal 8 does not fit with the horizontal plate part 15B of the electrode block 7B, but fits with the vertical plate part 14B. Thereby, the pedestal 8 is arranged so as not to come into contact with the substrate 2.

Also in this embodiment configured as described above, the same effects as in the first embodiment can be obtained.

In the first and second embodiments, the pedestal 8 has been described as having fitting grooves 18A and 18B that fit into the electrode blocks 7A and 7B, respectively, but the present invention is not limited to this. The electrode blocks 7A, 7B may not have the fitting grooves 18A, 18B, and may be bonded to the electrode blocks 7A, 7B using an adhesive, for example.

Further, in the first and second embodiments, the case where the pedestal 8 is arranged so as not to come into contact with the substrate 2 has been described as an example, but the present invention is not limited to this. That is, for example, if the distance E between adjacent coils 5 in the longitudinal direction of the substrate 2 (see FIG. 8(a)) becomes relatively large, or if the flexibility of the substrate 2 is allowed to decrease slightly, the pedestal 8 may be configured to contact the substrate 2.

Furthermore, in the first and second embodiments, the electrode blocks 7A and 7B are arranged so as to be spaced apart from each other in the lateral direction of the substrate 2, but the present invention is not limited to this. That is, for example, if the distance E between adjacent coils 5 in the longitudinal direction of the substrate 2 becomes relatively large, or if the flexibility of the substrate 2 is allowed to decrease slightly, the electrode blocks 7A and 7B may be arranged so as to be spaced apart from each other in a direction other than the lateral direction.

Further, in the first and second embodiments, each coil set 3 has been described with reference to the case where it has the magnetic core 6, but the present invention is not limited to this, and the coil set 3 may not have the magnetic core 6. Further, in the first and second embodiments, the electrode blocks 7A and 7B are connected to the printed wiring of the board 2, but the invention is not limited to this, and for example, the electrode blocks 7A and 7B may be prepared separately from the board 2. May be connected to wiring.

1 Eddy current flaw detection probe 2 Board 3 Coil set 5 Coil 7A, 7B Electrode block 8 Pedestal 9A, 9B Output wires 14A, 14B Vertical plate portion 15A, 15B Horizontal plate portion 16A, 16B Horizontal plate portion 17 Insertion hole 18A, 18B Fitting groove

Claims (5)

An eddy current flaw detection probe comprising a flexible substrate and a plurality of coil sets arranged on the substrate,
Each coil set is
a coil adhered to the surface of the substrate;
an electrode block on one side that is adhered to the surface of the substrate and connected to a lead wire on the winding start side of the coil;
an electrode block on the other side that is adhered to the surface of the substrate and connected to a lead wire on the winding end side of the coil;
a non-conductive pedestal that holds the coil, the electrode block on one side, and the electrode block on the other side so that they do not move relative to each other ;
The pedestal has an insertion hole into which the coil is inserted, a fitting groove on one side that fits with the electrode block on one side, and a fitting groove on the other side that fits with the electrode block on the other side. An eddy current flaw detection probe characterized by: An eddy current flaw detection probe comprising a flexible substrate and a plurality of coil sets arranged on the substrate,
Each coil set is
a coil adhered to the surface of the substrate;
an electrode block on one side that is adhered to the surface of the substrate and connected to a lead wire on the winding start side of the coil;
an electrode block on the other side that is adhered to the surface of the substrate and connected to a lead wire on the winding end side of the coil;
a non-conductive pedestal that holds the coil, the electrode block on one side, and the electrode block on the other side so that they do not move relative to each other;
An eddy current flaw detection probe, wherein the pedestal is arranged so as not to come into contact with the substrate. The eddy current flaw detection probe according to claim 2 ,
The electrode block on one side and the electrode block on the other side are arranged so as to be spaced apart from each other in the lateral direction of the substrate,
An eddy current flaw detection probe characterized in that a depth dimension of the electrode block on the one side and a depth dimension of the electrode block on the other side in the longitudinal direction of the substrate are equal to or less than an outer diameter dimension of the coil. The eddy current flaw detection probe according to claim 2 ,
The electrode block on one side and the electrode block on the other side each include a vertical plate portion extending in a direction rising from the surface of the substrate, and a vertical plate portion extending in a direction along the surface of the substrate from the base end side of the vertical plate portion. A first horizontal plate part that extends and is bonded to the substrate, and a second horizontal plate part that extends in a direction along the surface of the substrate from the tip side of the vertical plate part, and has a cross section. is U-shaped,
The fitting groove on the one side of the pedestal does not fit with the first horizontal plate part of the electrode block on the one side, but fits into the vertical plate part and the second horizontal plate part of the electrode block on the one side. mated with
The fitting groove on the other side of the pedestal does not fit with the first horizontal plate part of the electrode block on the other side, but fits into the vertical plate part and the second horizontal plate part of the electrode block on the other side. An eddy current flaw detection probe characterized by being mated with. The eddy current flaw detection probe according to claim 2 ,
The electrode block on one side and the electrode block on the other side each include a vertical plate portion extending in a direction rising from the surface of the substrate, and a vertical plate portion extending in a direction along the surface of the substrate from the base end side of the vertical plate portion. and a horizontal plate portion that extends and is bonded to the substrate, and has an L-shaped cross section;
The fitting groove on the one side of the pedestal does not fit with the horizontal plate part of the electrode block on the one side, but fits with the vertical plate part of the electrode block on the one side,
The eddy current characterized in that the fitting groove on the other side of the pedestal does not fit with the horizontal plate part of the electrode block on the other side, but fits with the vertical plate part of the electrode block on the other side. Flaw detection probe.

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