JP2007108032A - Upper placing type eddy current flaw detection probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate the positioning or attaching work of a detection coil at the time of manufacture of the upper placing type eddy current flaw detection probe and to enhance the attaching strength of the detection coil in a tangential type upper placing type eddy current flaw detection probe. <P>SOLUTION: The upper placing type eddy current flaw detection probe 2 is composed of exciting coils 211 and 212, a bobbin 23 and the detection coil 22. The exciting coils 211 and 212 are wound in the same direction and the winding end of the exciting coil 211 is connected to the winding start part of the exciting coil 212 while an exciting power supply 3 is connected to the winding start part of the exciting coil 211 and the winding end of the exciting coil 212. The detection coil 22 is attached to the peripheral surface of the bobbin 23 between the exciting coils 211 and 212. The upper placing type eddy current flaw detection probe 2 is moved in the direction shown by an arrow X3 along the inspection surface 11 (flaw) of an inspection target 1 to perform flaw detection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a so-called tangential type top-type eddy current flaw probe comprising an excitation coil and a detection coil, wherein the coil axis of the excitation coil is parallel to the inspection surface of an object to be inspected.

  Conventionally, as one of the tangential top-mounted eddy current flaw detection probes, one using a uniform eddy current has been proposed (see, for example, Patent Document 1).

A conventional tangential top-mounted eddy current flaw detection probe will be described with reference to FIG.
8A is a plan view, FIG. 8B is a cross-sectional view in the X1 direction of FIG. 8A, and FIG. 8C is a cross-sectional view in the X2 direction of FIG. 8A.
The eddy current flaw detection probe 2 includes an excitation coil 21 and a detection coil 22. The excitation coil 21 is wound around a cylindrical bobbin 23, and the detection coil 22 is attached to the surface of the excitation coil 21. The detection coil 22 is arranged such that its coil surface (a surface orthogonal to the coil axis) is orthogonal to the coil surface of the excitation coil 21 and parallel to one inspection surface of the object to be inspected.

  When an exciting current is passed through the exciting coil 21, a uniform eddy current in the winding direction of the exciting coil 21 is generated on the inspection surface of the inspection object 1, but when there is a scratch 11 on the inspection surface of the inspection object 1. The uniformity is locally broken at the scratch. When the eddy current flaw detection probe 2 is moved in the X3 direction, an output voltage is not generated in the detection coil 22 in a region where the inspection surface of the inspection object 1 is not scratched, but an eddy current is uniform in a region where the scratch 11 is present. As a result, the output coil voltage is generated in the detection coil 22 and a so-called scratch signal is generated.

JP 2004-205212 A

The upper eddy current flaw detection probe shown in FIG. 8 must be arranged so that the coil surface of the detection coil 22 is orthogonal to the coil surface of the exciting coil 21 and parallel to the inspection surface of the object 1 to be inspected. However, since the detection coil 22 must be attached to the circumferential surface of the cylindrical excitation coil 21, it is difficult to adjust and position the angle of the detection coil, and the installation work of the detection coil 22 becomes difficult. Further, since the detection coil 22 is easily affected by noise unless it is attached to the central portion in the longitudinal direction of the exciting coil 21, it is difficult to position the central portion.
The detection coil 22 is attached to the circumferential surface of the cylindrical excitation coil 21 with an adhesive. However, it is difficult to bond the coil to the circumferential surface of the coil, and the contact surface of both the coils is small, so the adhesion strength of the detection coil 22 is increased. Can not.
The present invention is intended to solve the above-mentioned problems of the conventional eddy current flaw detection probe, and the angle and positioning of the detection coil is easy, and the tangential type of the structure capable of increasing the mounting strength of the detection coil. An object of the present invention is to provide a top-mounted eddy current flaw detection probe.

In order to achieve the object of the present invention, the upper eddy current flaw detection probe according to claim 1 comprises two excitation coils formed on a bobbin and a detection coil disposed between the two excitation coils. The detection coil is mounted on the peripheral surface of the bobbin so that its coil surface is orthogonal to the coil surface of the excitation coil and parallel to the inspection surface of the object to be inspected. It is connected so that it may occur.
The top eddy current flaw detection probe according to claim 2 is the top eddy current flaw detection probe according to claim 1, wherein the bobbin includes a core made of a magnetic material.
The upper eddy current flaw detection probe according to claim 3 is the upper eddy current flaw detection probe according to claim 1 or 2, wherein the detection coil is attached to a flat surface of the peripheral surface of the bobbin. The flat surface is formed to be orthogonal to the coil surface of the exciting coil and to be parallel to the inspection surface of the object to be inspected.
The upper eddy current flaw detection probe according to claim 4 is the upper eddy current flaw detection probe according to claim 1 or 2, wherein the detection coil is attached to a detection coil attachment shaft member attached to the bobbin. And the detection coil mounting shaft member is mounted in a direction perpendicular to the bobbin axis and perpendicular to the inspection surface of the object to be inspected.

Since the upper eddy current flaw detection probe of the present invention divides the excitation coil into two parts and the detection coil is attached to the peripheral surface of the bobbin between the two excitation coils, it can be easily attached to the substantially central portion of the excitation coil. it can.
Since the stationary eddy current flaw detection probe of the present invention has a magnetic core, the magnetic flux generated by both excitation coils can be effectively used for the generation of a uniform eddy current even if the excitation coil is divided into two.

Since the upper eddy current flaw detection probe of the present invention has a flat surface on which a detection coil is attached in advance to the bobbin, when the eddy current flaw detection probe is manufactured, it is detected only by attaching the detection coil to the flat surface. Since the position and angle of the coil are determined, the manufacturing operation is facilitated. Further, since the detection coil is attached to a flat surface, the adhesive strength is increased.
Since the position and angle of the detection coil are determined simply by inserting the detection coil opening into the detection coil attachment shaft member attached to the bobbin, the above-described eddy current flaw detection probe of the present invention can be easily manufactured. Further, since the detection coil mounting shaft member is inserted into the opening of the detection coil, the mounting strength of the detection coil is increased.

  A tangential top-mounted eddy current flaw detection probe according to an embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is used for the part common to each figure.

FIG. 1 shows the configuration of an upright eddy current flaw detection probe according to Embodiment 1 of the present invention.
1A is a plan view, FIG. 1B is a cross-sectional view in the X1 direction of FIG. 1A, and FIG. 1C is a cross-sectional view in the X2 direction of FIG. 1A.
The upright eddy current flaw detection probe 2 includes excitation coils 211 and 212 and a circular (pancake-shaped) detection coil 22. The excitation coils 211 and 212 are wound around a cylindrical bobbin 23, and the detection coil 22 is an excitation coil 211. , 212 are attached to the peripheral surface of the bobbin 23. The interval between the excitation coils 211 and 212 is preferably set to a size that allows the detection coil 22 to be disposed between the two coils, and is preferably slightly larger than the diameter of the detection coil 22. The exciting coils 211 and 212 have the same winding direction, and the end of winding of the exciting coil 211 is connected to the beginning of winding of the exciting coil 212 so that the directions of magnetic flux generated by both coils are the same. . An excitation power source 3 is connected to the start of winding of the excitation coil 211 and the end of winding of the excitation coil 212. When the winding directions of the exciting coils 211 and 212 are opposite, if the winding ends of both coils are connected and the exciting power source 3 is connected at the beginning of winding of both coils, the direction of the magnetic flux generated by both coils is the same. Become.

The detection coil 22 has a coil surface (a surface orthogonal to the coil axis (axis passing through the center of the coil)) orthogonal to the coil surfaces of the excitation coils 211 and 212 and parallel to one inspection surface of the object to be inspected. It is arranged in.
The flaw detection is performed by moving the eddy current flaw detection probe 2 along the inspection surface of the inspection object 1 in the X3 direction. Reference numeral 11 denotes a scratch on the device under test 1.
Here, the coil surface is a surface (opening surface) that is surrounded by the coil winding and is orthogonal to the coil axis (axis passing through the center of the coil).

  In the eddy current flaw detection probe 2 of FIG. 1, the excitation coil is divided into two excitation coils 211 and 212, and the detection coil 22 is arranged between the two coils. It can be attached to the approximate center of the exciting coils 211 and 212. Therefore, the positioning of the detection coil 22 is facilitated, and the manufacturing operation of the eddy current flaw detection probe 2 is facilitated.

FIG. 2 shows the configuration of an upright eddy current flaw detection probe according to Embodiment 2 of the present invention.
2A is a plan view, FIG. 2B is a cross-sectional view in the X1 direction of FIG. 2A, and FIG. 2C is a cross-sectional view in the X2 direction of FIG. 2A.
The second embodiment is basically the same as the first embodiment, but differs from the first embodiment in that the bobbin includes a core.
A core 24 made of a magnetic material is attached inside the bobbin 23. Since the eddy current flaw detection probe 2 has the exciting coil divided into two parts 211 and 212, the magnetic flux generated by the two exciting coils locally generates magnetic fluxes F11 and F12 in addition to the main magnetic flux F0. By providing the core 24, the magnetic fluxes of both exciting coils can be concentrated on the core 24. Therefore, the eddy current flaw detection probe 2 of FIG. 2 can reduce the magnetic fluxes F11 and F12, and the magnetic flux generated by the exciting coils 211 and 212 is effectively used to generate a uniform eddy current on the inspection surface of the inspection object. Can be used.

FIG. 3 shows the configuration of a bobbin of an upright eddy current flaw detection probe according to Embodiment 3 of the present invention.
3A is a plan view, FIGS. 3B1 and 3B2 are cross-sectional views in the X1 direction of FIG. 3A, and FIGS. 3C1 and 3C are those of FIG. It is sectional drawing of a X2 direction. FIGS. 3B2 and 3C2 show a state where the detection coil is not attached in FIGS. 3B1 and 3C1. In FIG. 3, the exciting coil is omitted.
A U-shaped concave portion 231 having a flat surface (bottom surface) for attaching the detection coil 22 is formed on the peripheral surface of the bobbin 23. The concave portion 231 is formed so as to be positioned between the two excitation coils, and the flat surface thereof is orthogonal to the coil surface of the excitation coil and parallel to the inspection surface of the object to be inspected, or the bobbin 23. It is formed so as to be orthogonal to the diameter direction (or the diameter direction of the exciting coil).

  The detection coil 22 can be positioned simply by adhering to the flat surface of the concave portion 231 and can be attached so as to be orthogonal to the coil surface of the exciting coil and parallel to the inspection surface of the object to be inspected. Therefore, when the eddy current flaw detection probe is manufactured, the detection coil 22 is simply adhered to the flat surface of the concave portion 231 and is placed at a predetermined position at a predetermined angle (perpendicular to the coil surface of the excitation coil and It can be attached (in parallel with the inspection surface), making the creation work easier. Moreover, since the detection coil 22 adheres to the flat surface of the concave portion 231, the adhesive strength increases.

  The concave portion 231 has a wall only in the direction of the axis of the bobbin 23 (the axis passing through the center of the bobbin), that is, in the longitudinal direction, but when the bobbin 23 is thick, the concave portion 231 is shaped like a mouth or a circle. Then, a hole (square or round dish-shaped part) having walls on all sides may be formed, and the detection coil 22 may be fitted into the hole. Further, the detection coil 22 can be attached by forming a convex portion on the flat surface of the concave portion 231 and inserting the central opening of the detection coil 22 into the convex portion. In this case, the positioning of the detection coil 22 is further facilitated by the convex portion, and the mounting strength is increased.

FIG. 4 shows the configuration of a bobbin of an upright eddy current flaw detection probe according to Embodiment 4 of the present invention.
4A is a plan view, FIG. 4B1 is a cross-sectional view in the X1 direction of FIG. 4A, and FIG. 4C1 is a cross-sectional view in the X2 direction of FIG. 4A. 4 (b2) and (c2) show modified examples of FIGS. 4 (a), (b1) and (c1). In FIG. 4, the exciting coil is omitted.

First, FIGS. 4A, 4B1 and 4C1 will be described.
A convex portion 232 having a flat surface on which the detection coil 22 is attached is formed on the peripheral surface of the bobbin 23. The convex portion 232 is formed so as to be positioned between the two excitation coils, and its flat surface is perpendicular to the coil surface of the excitation coil and parallel to the inspection surface of the object to be inspected, or a bobbin. It is formed so as to be orthogonal to the diameter direction of 23 (or the diameter direction of the exciting coil). Therefore, when the eddy current flaw detection probe is manufactured, the detection coil 22 is simply adhered to the flat surface of the convex portion 232, and at a predetermined position at a predetermined angle (perpendicular to the coil surface of the excitation coil, To be parallel to the inspection surface).

  The convex portion 232 is further formed with a convex portion 2321 on its flat surface as shown in FIGS. 4B2 and 4C2, and the convex portion 2321 is inserted into the central opening of the detection coil 22. A detection coil 22 can also be attached. In this case, the detection coil 22 is adhered to a flat surface, and the convex portion 2321 is inserted into the opening thereof, so that the detection coil 22 can be attached more firmly, and the convex portion 2321 can easily position the detection coil 22. Become.

FIG. 5 shows the configuration of a bobbin of an upright eddy current flaw detection probe according to Embodiment 5 of the present invention.
FIGS. 5A1 and 5B1 are cross-sectional views, and FIGS. 5A2 and 5B2 are perspective views.
FIGS. 5 (a1) and (a2) show an example in which a detection coil attachment shaft member that penetrates the bobbin is provided, and FIGS. 5 (b1) and (b2) provide a detection coil attachment shaft member that does not penetrate the bobbin. An example is shown. In FIG. 5, the exciting coil is omitted.

First, FIGS. 5A1 and 5A2 will be described.
A detection coil attachment shaft member 233 is attached to the bobbin 23. The detection coil mounting shaft member 233 passes through the bobbin 23, and the axial direction of the detection coil mounting shaft member 233 coincides with the diameter direction of the bobbin 23 or is orthogonal to the axis of the bobbin 23 (axis passing through the center of the bobbin). And it attaches so that it may orthogonally cross the inspection surface of a to-be-inspected object, The front-end | tip part 2331 is inserted in the opening part of the center of the detection coil 22. Since the detection coil 22 is adhered to the contact surface of the bobbin 23 and is fixed by the distal end portion 2331 of the detection coil attachment shaft member 233, the detection coil 22 can be firmly attached and when the eddy current flaw detection probe is assembled. By simply inserting the distal end portion 2331 of the detection coil 22 into the central opening of the detection coil 22, the detection coil 22 is placed at a predetermined position at a predetermined angle (perpendicular to the coil surface of the excitation coil and parallel to the inspection surface of the object to be inspected) Can be installed as).

Next, FIGS. 5B1 and 5B2 will be described.
The detection coil attachment shaft member 234 is attached to the bobbin 23 by inserting a fixing portion 2342 into the hole of the bobbin 23. The detection coil mounting shaft member 234 has an axial direction that coincides with the diameter direction of the bobbin 23 or is orthogonal to the axis of the bobbin 23 (axis passing through the center of the bobbin) and orthogonal to the inspection surface of the object to be inspected. The head 2341 is attached and inserted into the central opening of the detection coil 22. Since the detection coil 22 is adhered to the contact surface of the bobbin 23 and is fixed by the head portion 2341 of the detection coil attachment shaft member 234, the detection coil 22 can be firmly attached and an eddy current flaw detection probe is manufactured. When the head 2341 of the detection coil mounting shaft member 234 is simply inserted into the central opening of the detection coil 22, the inspection coil is inspected at a predetermined position at a predetermined angle (perpendicular to the coil surface of the exciting coil). Can be mounted parallel to the surface).
The detection coil attachment shaft member 234 may be configured such that screw portions are formed in both the hole portion of the bobbin 23 and the fixing portion 2342 and the fixing portion 2342 is screwed into the hole portion of the bobbin 23.

Here, the test results of the output characteristics of the upper eddy current flaw probe according to the present invention and the conventional upper eddy current flaw probe will be described with reference to FIGS.
FIG. 6A shows the above-described eddy current flaw detection probe of the present invention used in the test, FIG. 6B shows the conventional eddy current flaw detection probe used in the test, and FIG. FIG. 7B shows the output characteristics of the conventional upper eddy current flaw detection probe. FIG. 7B shows the output characteristics of the conventional upper eddy current flaw detection probe.
In FIG. 6, the outer diameter and length of the bobbin 23 are 8 mm and 10 mm, the outer diameter and length of the core 24 are 4 mm and 12 mm, the number of turns of the exciting coils 211 and 212 is 50, and the number of turns of the exciting coil 21 is 70 times, the coil wire diameter is 0.1 mm. The material of the core 24 is PC permalloy (Ni 78% permalloy).

The outer diameter, inner diameter, and thickness of the detection coil 22 are 3.5 mm, 2 mm, and 0.5 mm, the wire diameter of the detection coil 22 is 0.05 mm, and the number of turns of the detection coil 22 is 80 times.
The inspection object 1 was a plate of SM490 (rolled steel for welded structure), and scratches having a depth of 1 mm, a length of 4 mm, and a width of 0.2 mm were formed by electric discharge machining.
In the test, the frequency of the excitation power source was set to 25 Hz, the excitation current was set to 20 mA, the eddy current flaw detection probe 2 was moved in the direction of the arrow X3, and the detection voltage of the detection coil 22 was measured.

In FIG. 7, the vertical axis indicates the output voltage of the eddy current flaw detection probe 2 (detection coil 22), and the horizontal axis indicates the position of the eddy current flaw detection probe 2.
As for the output characteristics of the conventional eddy current flaw detection probe 2 shown in FIG. 7B, an output voltage is not generated before and after the scratch 11, but an output voltage is generated at the scratch 11. That is, the conventional eddy current flaw detection probe 2 can reliably detect the flaw 11 without generating lift-off noise. On the other hand, looking at the output characteristics of the eddy current flaw detection probe 2 of the present invention in FIG. 7A, it can be seen that substantially the same output characteristics as in FIG. 7B are obtained. That is, the eddy current flaw probe in which the excitation coil is divided into two and the detection coil is arranged between the two excitation coils as in the eddy current flaw probe 2 of the present invention is also substantially different from the eddy current flaw probe in which the excitation coil is not divided. It can be seen that the same output characteristics can be obtained.

  In each of the above-described embodiments, the bobbin has a cylindrical shape, but may be a polygonal cylindrical body such as a quadrangle.

1 shows a configuration of a top-type eddy current flaw detection probe according to Embodiment 1 of the present invention. The structure of the probe for eddy current flaw detection according to Example 2 of the present invention is shown. The structure of the bobbin of the top type eddy current flaw detection probe which concerns on Example 3 of this invention is shown. The structure of the bobbin of the top type eddy current flaw detection probe which concerns on Example 4 of this invention is shown. The structure of the bobbin of the top type eddy current flaw detection probe which concerns on Example 5 of this invention is shown. The invention of this application used for the test and a conventional probe for eddy current flaw detection are shown. The test results of the present invention and the conventional probe for detecting an eddy current in the prior art are shown. The structure of the conventional top-mounted eddy current flaw detection probe is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inspected object 11 Scratch 2 Stationary eddy current flaw detection probe 21, 211, 212 Excitation coil 22 Detection coil 23 Bobbin 24 Core 3 Excitation power supply F0, F11, F12 Magnetic flux

Claims (4)

  It consists of two excitation coils formed on the bobbin and a detection coil arranged between the two excitation coils. The detection coil has a coil surface orthogonal to the coil surface of the excitation coil and parallel to the inspection surface of the object to be inspected. The above-described eddy current flaw detection probe is attached to the peripheral surface of the bobbin so that the two exciting coils are connected to generate magnetic flux in the same direction.   2. The upper eddy current flaw detection probe according to claim 1, wherein the bobbin includes a core made of a magnetic material.   The top-type eddy current flaw detection probe according to claim 1 or 2, wherein the detection coil is attached to a flat surface of a peripheral surface of the bobbin, and the flat surface is orthogonal to a coil surface of the excitation coil. The above-described eddy current flaw detection probe is formed so as to be parallel to the inspection surface of the object to be inspected.   3. The upper eddy current flaw detection probe according to claim 1, wherein the detection coil is attached to a detection coil attachment shaft member attached to the bobbin, and the detection coil attachment shaft member is connected to a bobbin shaft. An overhead eddy current flaw detection probe characterized in that the probe is mounted in a direction perpendicular to the inspection surface of the object to be inspected.

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