Coil module, eddy current testing probe, and eddy current testing apparatus
The coil module design simplifies the assembly of cross coils by inserting first and second coils into a holder, reducing manufacturing costs and times while ensuring accurate eddy current detection.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- MITSUBISHI HEAVY IND LTD
- Filing Date
- 2022-08-30
- Publication Date
- 2026-06-05
AI Technical Summary
The manufacturing of cross coils for eddy current flaw detection is difficult to automate, leading to increased costs and prolonged manufacturing times, especially when creating array probes requiring multiple cross coils.
A coil module design comprising a first coil forming an annular shape around a first axis, a second coil forming an annular shape around a second axis orthogonal to the first, and a coil holder with recesses for holding cross coils, allowing for easy assembly by inserting the first coil into the second coil and then into the holder, eliminating the need for alternate winding.
This configuration enables low-cost and time-efficient manufacturing of eddy current testing probes with improved detection accuracy and reduced interference between coils, facilitating wider area inspection with finer data pitch.
Smart Images
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Abstract
Description
Technical Field
[0001] The present disclosure relates to a coil module, an eddy current flaw detection probe, and an eddy current flaw detection device.
Background Art
[0002] As a method for non-destructively inspecting defects such as scratches and wall thickness reduction in pipes and the like, an eddy current flaw detection method is known. In this method, a conventional cross coil having an exciting coil that forms an eddy current from the inner surface to the outer surface of the pipe, a detection coil that detects the disturbance of the eddy current generated at a defective portion of the pipe, and a winding frame for winding the windings of these exciting coil and detection coil is generally used (see, for example, Patent Document 1 below).
[0003] When manufacturing a cross coil, a method of alternately winding the windings of the exciting coil and the detection coil around the above-described winding frame is adopted. That is, after winding the winding of the exciting coil, it is necessary to repeatedly perform an operation of winding the winding of the detection coil from a direction intersecting the exciting coil.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention Invention
[0005] However, when manufacturing a cross coil using the above-described winding frame, it is difficult to automate the operation, and an increase in the cost required for manufacturing and a lengthening of the manufacturing period have been problems. In particular, when creating an array probe for eddy current flaw detection that requires a large number of cross coils, the period required for manufacturing the cross coils has been a significant bottleneck
[0006] This disclosure was made to solve the above problems and aims to provide a coil module, an eddy current testing probe, and an eddy current testing apparatus that can be manufactured at low cost and in a short time. [Means for solving the problem]
[0007] To solve the above problems, the coil module according to this disclosure comprises a first coil forming an annular shape surrounding a first axis, and the first axis Approximately orthogonal A cross coil having a second coil that forms an annular shape surrounding a second axis and covers a part of the outer circumference of the first coil, and a coil holder having a receiving recess formed therein that holds a plurality of cross coils arranged in an arrangement direction that intersects the first axis and the second axis in the plane formed by the first axis and the second axis, wherein the receiving recess is formed by a plurality of cross grooves arranged in the arrangement direction, in which a groove into which the first coil can be inserted and a groove into which the second coil can be inserted intersect, and in a pair of adjacent cross coils in the arrangement direction, In the second axial direction, at least a portion of the first coil of the cross coil on one side in the arrangement direction faces a portion of the second coil of the cross coil on the other side in the arrangement direction, and in the second axial direction, at least a portion of the first coil of the cross coil on the other side faces a portion of the second coil of the cross coil on one side, and in the first axial direction, a portion of the first coil of the cross coil on one side faces a portion of the first coil of the cross coil on the other side.
[0008] The eddy current testing probe according to this disclosure comprises the above-mentioned coil module and an outer casing for holding the coil module.
[0009] The eddy current flaw detection apparatus according to this disclosure comprises the above-mentioned eddy current flaw detection probe and a power supply unit that supplies alternating current to the eddy current flaw detection probe. [Effects of the Invention]
[0010] This disclosure provides a coil module, an eddy current testing probe, and an eddy current testing apparatus that can be manufactured at low cost and in a short time. [Brief explanation of the drawing]
[0011] [Figure 1] This is a schematic diagram showing the configuration of an eddy current flaw detection apparatus according to the first embodiment of this disclosure. [Figure 2] This is a side view showing the configuration of an eddy current flaw detection probe according to the first embodiment of this disclosure. [Figure 3] This is a side view showing the configuration of a coil module according to the first embodiment of this disclosure. [Figure 4] This is a perspective view showing the configuration of a coil holder according to the first embodiment of this disclosure. [Figure 5] This is a view of the cross coil according to the first embodiment of the present disclosure, as seen from the first axial direction. [Figure 6] This is a view of the cross coil according to the first embodiment of the present disclosure, as seen from the second axial direction. [Figure 7] This is a perspective view showing a first modified example of the cross coil according to the first embodiment of this disclosure. [Figure 8] This is a perspective view showing a second modified example of the cross coil according to the first embodiment of this disclosure. [Figure 9] This is a perspective view showing a third modified example of the cross coil according to the first embodiment of this disclosure. [Figure 10] This figure shows a fourth modified example of the cross coil according to the first embodiment of this disclosure. [Figure 11] This is a plan view showing the configuration of a coil module according to the second embodiment of this disclosure. [Modes for carrying out the invention]
[0012] <First Embodiment> (Configuration of an eddy current flaw detection device) Hereinafter, the eddy current flaw detection apparatus 1, eddy current flaw detection probe 10, and coil module 20 according to the first embodiment of this disclosure will be described with reference to Figures 1 to 6.
[0013] The eddy current flaw detection device 1 is a device that, when inserted inside, for example, the heat transfer tubes of a steam generator in a nuclear power plant, or various other pipes, ducts, etc. (hereinafter referred to as "pipes, etc."), scans the surface of the object to detect defects (cracks or thinning) that have occurred in the object.
[0014] As shown in FIG. 1, the eddy current flaw detector 1 includes an eddy current flaw detection probe 10, a switch unit 30, a power supply unit 40, and a flaw detector main body 50.
[0015] The eddy current flaw detection probe 10 is inserted into the inside of a pipe and used. The power supply unit 40 applies an alternating voltage to the eddy current flaw detection probe to generate a magnetic field from a coil module 20 described later. By scanning the eddy current flaw detection probe 10 along the surface of the pipe, when passing through a defective part, the eddy current generated in the pipe by the magnetic field from the coil module 20 (that is, the eddy current generated in the pipe material by the alternating current generated in the coil module 20) is disturbed. The flaw detector main body 50 is a device that digitizes or images this eddy current disturbance and visually conveys it to an operator. The switch unit 30 is a device for switching the supply state (operation mode) of the alternating current flowing through the coil module 20.
[0016] (Configuration of Eddy Current Flaw Detection Probe) As shown in FIG. 2, the eddy current flaw detection probe 10 has an outer casing 11, a cable 12, a coil module 20, and a holding ring 13.
[0017] The outer casing 11 is formed of a material having flexibility that can be freely bent inside the pipe. Inside the outer casing 11, various wiring materials extending from the cable 12 connected to the above-mentioned power supply unit 40 and the like are accommodated. At an intermediate position in the extension of the outer casing 11, the coil module 20 and a pair of holding rings 13 are provided. The holding ring 13 holds the coil module 20 immovably from both sides in the extension direction of the outer casing 11.
[0018] As shown in Figure 3, the coil module 20 has a plurality of cross coils 21 and a coil holder 22. The orientation and shape of the cross coils 21 are held by the coil holder 22. As shown in Figure 3 or Figure 4, the coil holder 22 is annular in shape with axis O as the center. A housing recess 23 for housing the plurality of cross coils 21 is formed on the outer circumferential surface of the coil holder 22. The housing recess 23 is recessed from the outer circumferential surface of the coil holder 22 toward the inner circumference and is formed continuously in the circumferential direction. When housed in the housing recess 23, the cross coils 21 are arranged in contact with each other in the circumferential direction. Hereinafter, the direction in which the cross coils 21 are arranged (i.e., the circumferential direction of the coil holder 22) may simply be referred to as the "arrangement direction". Preferably, the coil holder 22 is formed by three-dimensional additive manufacturing using, for example, resin.
[0019] As shown in Figures 5 and 6, the cross coil 21 has a first coil 61 and a second coil 62. The first coil 61 is an annular shape centered on the first axis A1. The first coil 61 only needs to be an annular shape that surrounds the first axis A1 from the outside, and the center of the first coil 61 does not necessarily have to be located on the first axis A1. The first axis A1 extends in a direction that intersects the axis O in the plane along the outer surface of the coil holder 22. Furthermore, the first coil 61 has an isosceles trapezoidal shape when viewed from the direction of the first axis A1, with the radially inward side relative to axis O as the upper base and the radially outward side as the lower base. In addition, the upper base is shorter than the lower base. That is, the end face of the first coil 61 facing radially inward is formed to be smaller than the end face facing radially outward. Note that the above "trapezoidal shape" does not necessarily refer to a "rectangular shape with perfectly parallel upper and lower bases". In other words, the top and bottom bases may be slightly misaligned due to manufacturing errors or design tolerances. The same applies to the term "equal feet"; the angle between the feet and the top or bottom base may be slightly different on the left and right sides.
[0020] The second coil 62 forms a rectangular ring centered on the second axis A2, which intersects the first axis A1. The second coil 62 only needs to form a ring surrounding the second axis A2 from the outside; its center does not necessarily have to be located on the second axis A2. For example, the first axis A1 and the second axis A2 are perpendicular. The first coil 61 is fitted inside the second coil 62. In other words, the second coil 62 covers a portion of the outer surface of the first coil 61. Therefore, the inner opening dimensions of the second coil 62 are set to be equal to or slightly larger than the outer dimensions of the first coil 61. Thus, the first coil 61 is inserted into the inner opening of the second coil 62.
[0021] Ideally, the first coil 61 and the second coil 62 are perpendicular to each other at their centers in the direction of the first axis A1 and the second axis A2. However, even if the centers of the first coil 61 and the second coil 62 are slightly misaligned, it will not affect the detection accuracy, or will only have a very slight effect. Therefore, the dimensional accuracy of the coil holder 22 may have a manufacturing error that allows for such a misalignment.
[0022] As a result, the first coil 61 and the second coil 62 are combined in a cross-coil configuration. For example, the first coil 61 functions as a detection coil, and the second coil 62 functions as an excitation coil. The excitation coil generates eddy currents in the region from the inner surface to the outer surface of the pipe or other material. The detection coil detects the disturbed component when these eddy currents are disturbed by defects such as cracks or thinning. In another example, the second coil 62 can function as a detection coil, and the first coil 61 can function as an excitation coil.
[0023] The cross coils 21 described above are arranged in a direction that is tolerant to the first axis A1 and the second axis A2 of the first coil 61 (i.e., in the "arrangement direction" described above) within the plane formed by the first axis A1 of the first coil 61 and the second axis A2 of the second coil 62. When housed in the coil holder 22, in a pair of cross coils 21 adjacent to each other in the circumferential direction, the first coil 61 of one cross coil 21 abuts against the second coil 62 of the other cross coil 21. Also, the second coil 62 of one cross coil 21 abuts against the first coil 61 of the other cross coil 21. As a result, the distance between the centers of each cross coil 21 is The external dimensions in the circumferential direction are kept to about 50%. Furthermore, on the coil holder 22, the first axis A1 and the second axis A2 each form a 45° angle with respect to the arrangement direction. Note that the first coil 61 of one cross coil 21 does not have to be in contact with the second coil 62 of the other cross coil 21, and they may face each other with a gap between them. Similarly, the second coil 62 of one cross coil 21 does not have to be in contact with the first coil 61 of the other cross coil 21, and they may face each other with a gap between them. In other words, the above "contact" refers to a state where they face each other with no gap between them.
[0024] (Effects and Benefits) Next, an example of how to use the eddy current testing apparatus 1 and the eddy current testing probe 10 described above will be explained. When using the eddy current testing apparatus 1, first, the power supply unit 40 supplies alternating current to each coil module 20 of the eddy current testing probe 10. In addition, the switch unit 30 switches the coils that are sequentially energized. In this state, the eddy current testing probe 10 is scanned along the inner or outer surface of a pipe or the like. When each coil module 20 detects a defect, the testing apparatus body 50 identifies the location of the defect and collects a signal that helps to confirm its properties such as depth and length.
[0025] Conventionally, when manufacturing the cross coil 21, the method used was to alternately wind the excitation coil winding and the detection coil winding onto the winding frame. In other words, it was necessary to wind the excitation coil winding first, and then wind the detection coil winding from a direction intersecting the excitation coil, and repeat this process.
[0026] However, when manufacturing cross coils 21 using the above-described winding frame, it is difficult to automate the process, leading to increased manufacturing costs and longer manufacturing times. In particular, when creating array probes for eddy current testing that require a large number of cross coils 21, the time required to manufacture the cross coils 21 became a significant bottleneck. Therefore, in this embodiment, the above-described configurations are adopted.
[0027] According to the above configuration, after assembling the cross coil 21 by inserting the first coil 61 inside the second coil 62, the coil module 20 can be easily manufactured by sequentially inserting the cross coil 21 into the receiving recess 23 of the coil holder 22. In addition, coils with a simple annular shape can be mass-produced at low cost and with short lead times through automation. This eliminates the need to alternately wind the wires onto the reel as in the conventional method. As a result, it is possible to achieve both reduced manufacturing costs and shorter lead times.
[0028] Furthermore, since no winding frame is used, the spacing between cross coils 21 can be further reduced. As a result, a large number of cross coils 21 can be densely arranged in a single coil holder 22, making it possible to perform flaw detection inspection over a wider area with a finer data pitch. Specifically, sufficient detection accuracy can be ensured with only one coil module 20, without arranging multiple annular coil holders 22 in the direction of axis O. As a result, the manufacturing and operating costs of the eddy current flaw detection probe 10 can be further reduced.
[0029] Furthermore, with the above configuration, the coil holder 22 is annular in shape, allowing the cross coils 21 to be precisely arranged in an annular shape while maintaining their shape and orientation. This makes it possible to easily apply the coil module 20 to eddy current testing probes 10 used for inspecting pipes, etc.
[0030] In addition, with the above configuration, the radially inner portion of the trapezoidal first coil 61 is shorter than the outer portion. As a result, when multiple cross coils 21 are arranged on the coil holder 22, the radially inner portions do not interfere with each other. Consequently, during the assembly of the coil module 20, no special measures are required to avoid interference between the cross coils 21; the cross coils 21 can simply be inserted into the coil holder 22. Therefore, the assembly process is made easier, and deformation or damage to the cross coils 21 during assembly can be avoided.
[0031] The first embodiment of this disclosure has been described above. Various changes and modifications can be made to the above configuration without departing from the gist of this disclosure.
[0032] For example, as shown in Figure 7 as the first modified example, the width of the first coil 61 (dimension in the direction of the first axis A1: number of turns) may be made larger than the width of the second coil 62 (dimension in the direction of the second axis A2). This can increase the signal strength.
[0033] As a second modification, as shown in Figure 8, the first coil 61 may be formed in a ring shape and the second coil 62 in a rectangular ring shape. In this case, a part of the first coil 61 extends into the inside of the adjacent second coil 62, which can further increase the signal strength.
[0034] Furthermore, as a third modification, as shown in Figure 9, the width of the first coil 61 may be made larger than in the second modification. This configuration also makes it possible to improve the signal strength.
[0035] In addition, as shown in Figure 10 as a fourth modified example, it is also possible to adopt a configuration in which the first coil 61 and the second coil 62 intersect at an angle of less than 90°. That is, the angle θ between the first axis A1 and the second axis A2 is less than 90°. Here, if the first axis A1 and the second axis A2 are perpendicular, the detection accuracy of defects occurring in the direction of the central axis of the pipe may decrease depending on the shape of the pipe, etc. With the above configuration, since the first axis A1 and the second axis A2 intersect at an angle of less than 90°, the eddy current component crossing the defect in the direction of the central axis increases. As a result, sufficient detection accuracy can be ensured.
[0036] Furthermore, although the first embodiment described above has a configuration having only one coil holder 22, the number of coil holders 22 is not limited to one, and may be two or more.
[0037] <Second Embodiment> Next, a second embodiment of the present disclosure will be described with reference to Figure 11. Components similar to those in the first embodiment are denoted by the same reference numerals, and detailed descriptions are omitted. As shown in the figure, the coil module 120 according to this embodiment has a different shape for the coil holder 122 compared to the first embodiment.
[0038] The coil holder 122 is plate-shaped and formed along the plane formed by the first axis A1 and the second axis A2. The coil holder 122 has a receiving recess 123 for accommodating multiple cross coils 21. In other words, the coil holder 122 has a thickness greater than the dimensions of the cross coils 21. The multiple cross coils 21 are arranged linearly on the coil holder 122.
[0039] With the above configuration, since the coil holder 122 is plate-shaped, the coil module 120 can be brought into contact with a flat object to be inspected without any gaps. This enables highly accurate flaw detection inspection of the flat object to be inspected. Furthermore, similar to the first embodiment, if a coil holder 122 is prepared, the coil module 120 can be easily manufactured by fitting the cross coil 21 into the coil holder 122. This makes it possible to achieve a significant reduction in manufacturing and operating costs.
[0040] The second embodiment of this disclosure has been described above. It is possible to make various changes and modifications to the above configuration without departing from the gist of this disclosure.
[0041] <Note> The coil module 20, eddy current testing probe 10, and eddy current testing apparatus 1 described in each embodiment can be understood, for example, as follows.
[0042] (1) The coil module 20 according to the first embodiment comprises a cross coil 21 having a first coil 61 that forms an annular shape surrounding a first axis A1, and a second coil 62 that forms an annular shape surrounding a second axis A2 that intersects the first axis A1 and covers a part of the outer circumference of the first coil 61, and a coil holder 22 having a receiving recess 23 formed therein that holds the plurality of cross coils 21 when the plurality of cross coils 21 are arranged in an arrangement direction that intersects the first axis A1 and the second axis A2, wherein in a pair of adjacent cross coils 21 in the arrangement direction, the first coil 61 of one cross coil 21 faces the second coil 62 of the other cross coil 21, and the second coil 62 of one cross coil 21 faces the first coil 61 of the other cross coil 21.
[0043] According to the above configuration, the coil module 20 can be easily manufactured by first inserting the first coil 61 inside the second coil 62 to assemble the cross coil 21, and then sequentially inserting the cross coil 21 into the housing recess 23 of the coil holder 22. This makes it possible to achieve both a reduction in manufacturing costs and a shortening of the manufacturing period.
[0044] (2) The coil module 20 according to the second embodiment is the coil module 20 of (1), wherein the coil holder 22 is plate-shaped and extends along the plane formed by the first axis A1 and the second axis A2.
[0045] With the above configuration, since the coil holder 22 is plate-shaped, the coil module 20 can be brought into contact with a flat object to be inspected without any gaps, enabling highly accurate flaw detection inspection.
[0046] (3) The coil module 20 according to the third embodiment is the coil module 20 of (1), wherein the coil holder 22 is annular in shape with respect to an axis O whose direction of arrangement is the circumferential direction.
[0047] With the above configuration, the coil holder 22 is annular in shape, allowing the cross coils 21 to be precisely arranged in an annular pattern. This makes it possible to easily apply the coil module 20 to eddy current testing probes 10 used for inspecting pipes, etc.
[0048] (4) The coil module 20 according to the fourth embodiment is the coil module 20 of (3), wherein the first coil 61 has a trapezoidal shape, with the portion radially inward relative to the axis O being the upper base and the portion radially outward being the lower base when viewed from the direction of the first axis A1, and the upper base being shorter than the lower base.
[0049] According to the above configuration, the radially inner portion of the trapezoidal first coil 61 is shorter than the outer portion. Therefore, when multiple cross coils 21 are arranged on the coil holder 22, the radially inner portions do not interfere with each other. This makes assembly easier and prevents deformation or damage to the cross coils 21 during assembly.
[0050] (5) The coil module 20 according to the fifth embodiment is the coil module 20 of (3) or (4), wherein the first axis A1 and the second axis A2 intersect at an angle of less than 90°.
[0051] In this case, if the first axis A1 and the second axis A2 are perpendicular, the detection accuracy of defects occurring in the direction of the central axis of the pipe may decrease depending on the shape of the pipe. With the above configuration, since the first axis A1 and the second axis A2 intersect at an angle of less than 90°, the eddy current component crossing the defect in the direction of the central axis increases. As a result, sufficient defect detection accuracy can be ensured.
[0052] (6) The eddy current testing probe 10 according to the sixth embodiment comprises a coil module 20 according to any one embodiment of (1) to (5), and an outer casing 11 that holds the coil module 20.
[0053] According to the above configuration, it is possible to provide an eddy current testing probe 10 that can be manufactured at low cost and in a short time.
[0054] (7) The coil module 20 according to the seventh embodiment comprises the eddy current testing probe 10 of (6) and a power supply unit 40 that supplies alternating current to the eddy current testing probe 10.
[0055] According to the above configuration, it is possible to provide an eddy current flaw detection device 1 that can be manufactured at low cost and in a short time. [Explanation of Symbols]
[0056] 1...Eddy current flaw detection device 10…Eddy current testing probe 11…Exterior 12… Cable 13…Retaining ring 20… Coil Module 21…Cross coil 22... Coil holder 23… Storage recess 30…Switch section 40...Power supply section 50…Flaw detection device body 61...First Coil 62... Second coil 120... Coil Module 122... Coil holder 123... Storage recess A1…first axis line A2…Second axis O…Axis line
Claims
1. A cross coil having a first coil that forms an annular shape surrounding a first axis, and a second coil that forms an annular shape surrounding a second axis substantially perpendicular to the first axis and covers a part of the outer circumference of the first coil, A coil holder having a housing recess formed therein, in which a plurality of cross coils are arranged in an arrangement direction extending in a direction intersecting the first axis and the second axis within the plane formed by the first axis and the second axis, and the plurality of cross coils are held in place. Equipped with, The aforementioned accommodating recess is formed by arranging a plurality of cross grooves in the direction of arrangement, each cross groove being capable of accommodating the cross coils, where a groove into which the first coil can be inserted intersects with a groove into which the second coil can be inserted. In the pair of cross coils adjacent to each other in the direction of the arrangement, A coil module in which, in the second axial direction, at least a portion of the first coil of the cross coil on one side in the arrangement direction faces a portion of the second coil of the cross coil on the other side in the arrangement direction, and in the second axial direction, at least a portion of the first coil of the cross coil on the other side faces a portion of the second coil of the cross coil on one side, and in the first axial direction, a portion of the first coil of the cross coil on one side faces a portion of the first coil of the cross coil on the other side.
2. The coil module according to claim 1, wherein in a pair of adjacent cross coils in the direction of arrangement, the first coil of one cross coil and the second coil of the other cross coil are in contact with each other, and the second coil of one cross coil and the first coil of the other cross coil are in contact with each other.
3. The coil module according to claim 1, wherein the receiving recess is recessed from the outer surface of the coil holder and extends continuously in the direction of arrangement.
4. The coil module according to any one of claims 1 to 3, wherein the coil holder is plate-shaped and extends along the plane formed by the first axis and the second axis.
5. The coil module according to any one of claims 1 to 3, wherein the coil holder is annular in shape with respect to an axis whose circumferential direction is the direction of arrangement.
6. The coil module according to claim 5, wherein the first coil has a trapezoidal shape, with the portion radially inward relative to the axis being the upper base and the portion radially outward being the lower base when viewed from the first axial direction, and the upper base is shorter than the lower base.
7. The coil module according to any one of claims 1 to 3, wherein the first axis and the second axis intersect at an angle of less than 90°.
8. The coil module according to claim 1, An outer casing that holds the coil module, A probe for eddy current testing equipped with the following features.
9. The eddy current testing probe according to claim 8, A power supply unit that supplies alternating current to the eddy current flaw detection probe, An eddy current flaw detection device equipped with the following features.