JP2007248169A - Eddy current flaw detection probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an eddy current flaw detection probe, wherein a vertically placed detection coil is arranged inside an exciting coil, capable of detecting flaws in full directions for a large area by moving an eddy current flaw detection probe in the scanning direction while rotating the detection coil. <P>SOLUTION: The eddy current flaw detection probe 2 consists of the exciting coil 21 and the detection coil 22 and has the vertically placed detection coil 22 arranged in the exciting coil 21 so as to rotate the coil. The eddy current flaw detection probe 2 moves in the Y-direction while rotating the detection coil 22 around the rotation axis P1. The locus of the detection coil 21 at that time is shown as in the drawing, and the detection coil moves with changing the direction. Thereby, the flaws in the full different directions such as the flaws F1-F4 can be detected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an eddy current flaw detection probe that moves in a scanning direction while rotating a detection coil.

Conventionally, an eddy current flaw detection probe that detects a scratch in various directions by rotating a detection coil in an exciting coil has been proposed (see, for example, Patent Document 1).
A conventional eddy current flaw detection probe will be described with reference to FIGS.
FIG. 7 shows the configuration of the eddy current flaw detection probe.
FIG. 7A is a plan view of the eddy current flaw detection probe, and FIGS. 7B-1 and 7B-1 are perspective views of an excitation coil and a detection coil.
The eddy current flaw detection probe 1 includes a pancake-shaped excitation coil 11 and a rectangular detection coil 12. The excitation coil 11 has a coil axis (axis passing through the center of the coil) orthogonal to the inspection surface of the inspection object T. (The coil surface is parallel to the inspection surface), and the detection coil 12 has an excitation coil 11 in which the coil surface (opening surface surrounded by the winding) is the inspection surface of the object T to be inspected. They are arranged so as to be orthogonal. The detection coil 12 is rotated in the excitation coil 11 by a motor (not shown).

Next, flaw detection using the eddy current flaw detection probe of FIG. 7 will be described with reference to FIG.
When the flaws F1 to F4 of the inspection object T are detected by the eddy current flaw detection probe 1 of FIG. 7, for example, as shown in FIG. 8A, the clockwise direction (arrows) around the center point P1 of the detection coil 12 Each time the detection coil 12 rotates once, the eddy current flaw detection probe 1 is intermittently moved along the line L to, for example, positions X1, X2, and X3 in FIG. The detection coil 12 is rotated once at the position for flaw detection.

  When the detection coil 12 rotates clockwise at the positions X1, X2, and X3, the trajectory for one rotation of the detection coil 12 is as shown in FIGS. 8C-1 and 8C-2. FIG. 8C-1 shows a locus for the first half of one rotation, and FIG. 8C-2 shows a locus for the second half of the rotation. 8 (c-1) and (c-2) are shown separately, but they are a locus for one rotation at the same position X1 and the like together. 8 (c-1) and (c-2) are provided with arrows for the sake of convenience in order to make the direction of the detection coil 12 easy to understand.

  Since the eddy current generated by the flaw flows along the flaw, the detection sensitivity of the detection coil 12 is when the coil surface of the detection coil 12 is parallel to the longitudinal direction of the flaw (the winding is parallel to the longitudinal direction of the flaw). Highest, lowest when orthogonal. Therefore, it is necessary to select the positions X1, X2, and X3 of the eddy current flaw detection probe 1 so that the center point P1 is positioned in the vicinity of the flaw. However, before flaw detection, the positions of the flaws F1 to F4 are not known. It is difficult to set and control the amount of movement when moving the eddy current flaw detection probe 1 in the scanning direction. For example, the eddy current flaw detection probe 1 moves to the position X2 after making one rotation at the position X1, and then makes one rotation at the position X2. Then, since it moves intermittently, such as moving to position X3, the moving speed becomes slow and the flaw detection time becomes long.

JP 2002-214202 A

  The present invention aims to solve the above-mentioned problems of the conventional eddy current flaw detection probe. The eddy current flaw detection probe is continuously moved in the scanning direction while rotating the detection coil, and a wide range of omnidirectional flaws are detected. An object of the present invention is to provide an eddy current flaw detection probe capable of detecting a high-sensitivity in a short time.

In order to achieve the object of the present invention, the eddy current flaw detection probe according to claim 1 includes an excitation coil and a detection coil disposed in the excitation coil, and the coil surface of the excitation coil and the coil surface of the detection coil are: In the eddy current flaw detection probe arranged so as to be orthogonal, the eddy current flaw detection probe or the detection coil is moved in the scanning direction while rotating around a rotation axis.
The eddy current flaw detection probe according to claim 2 includes an excitation coil and a detection coil arranged in the excitation coil, and the coil surface of the excitation coil and the coil surface of the detection coil are arranged so as to be orthogonal to each other. Two or more probes are provided, and the two or more eddy current flaw detection probes are arranged around one rotation axis and move in the scanning direction while rotating around the rotation axis.
The eddy current flaw detection probe according to claim 3 includes one excitation coil and two or more detection coils arranged in the excitation coil, and includes a coil surface of one excitation coil and two or more detection coils. In the eddy current flaw detection probe arranged so that the coil surfaces are orthogonal to each other, two or more detection coils are moved in the scanning direction while rotating about the rotation axis of each detection coil.
The eddy current flaw detection probe according to claim 4 includes one excitation coil and two or more detection coils arranged in the excitation coil, and includes a coil surface of one excitation coil and two or more detection coils. In the eddy current flaw detection probe arranged so that the coil surfaces are orthogonal to each other, two or more detection coils are arranged around one rotating shaft, and rotate in the scanning direction while rotating around the rotating shaft. It is characterized by moving

  Since the eddy current flaw detection probe of the present invention moves the detection coil or the eddy current flaw detection probe in the scanning direction while rotating around the rotation axis, each radius of each detection coil or detection coil arranged around the rotation axis. The trajectories that pass through intersect. Therefore, the eddy current flaw detection probe can continuously detect scratches in all directions in a wide range. By changing the moving speed in the scanning direction of the eddy current flaw detection probe and changing the moving distance in the scanning direction during one rotation of the detection coil, the flaw detection state is taken into consideration. Accuracy or detection sensitivity can be adjusted. In addition, the detection accuracy or detection sensitivity of the flaw can be adjusted by changing the moving distance of the detection coil by changing the rotational speed of the eddy current flaw detection probe or the detection coil. Further, by changing the rotation direction of the detection coil or the eddy current flaw detection probe, the pattern of the locus of the detection coil can be reversed.

  In the present invention, two or more eddy current flaw detection probes are juxtaposed and each detection coil is rotated around a separate rotation axis, or by rotating around one rotation axis, the flaw detection width ( Detection width) can be further increased. Further, the pattern of the detection coil trajectory can be changed by changing the arrangement of the detection coils of two or more eddy current flaw detection probes. Furthermore, when the detection coils of two or more eddy current flaw detection probes are rotated separately, the pattern of the detection coil trajectory can be reversed by changing the rotation direction of each detection coil.

  In the eddy current flaw detection probe according to the present invention, since two or more detection coils are arranged in one excitation coil, the structure of the eddy current flaw detection probe is simplified, and the excitation coil is interposed between the detection coils. Since no winding is interposed, both detection coils can be brought closer to each other, and scratches between both detection coils can be detected with high sensitivity.

  An 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 eddy current flaw detection probe according to an embodiment of the present invention.
1A is a plan view of an eddy current flaw detection probe, FIGS. 1B-1 and 1B-2 are perspective views of an excitation coil and a detection coil, and FIG. 1C is a perspective view of the detection coil. FIG.
The eddy current flaw detection probe 2 includes a pancake excitation coil 21 and a square detection coil 22, and a vertical detection coil 22 (so-called tangential coil) is disposed in the excitation coil 21. That is, the eddy current flaw detection probe 2 is arranged so that the coil surface of the excitation coil 21 and the coil surface of the detection coil 22 are orthogonal (or the coil axis of the excitation coil 21 and the coil axis of the detection coil 22 are orthogonal). is there. The exciting coil 21 is arranged so that its coil axis is orthogonal to the inspection surface of the inspection object T (so that the coil surface is parallel to the inspection surface). Here, the coil axis is an axis passing through the center of the coil, and the coil surface is an opening surface surrounded by coil windings, that is, a surface orthogonal to the coil axis. The same applies hereinafter.
The detection coil 22 is not limited to a quadrangle, and may be a triangle as shown in FIG. 1C, or may be a pentagon, a circle, an ellipse, or the like. Further, the exciting coil 21 is not limited to a pancake-shaped one, but may be a polygonal shape such as a quadrangle, an elliptical shape, or the like.

The eddy current flaw detection probe 2 is attached to a support member (not shown), and the support member is moved in the Y direction (scanning direction or flaw detection) at a predetermined speed by a moving means for driving a commonly used roller or wheel with a motor. Direction). At that time, the detection coil 22 is rotated around the rotation axis P1 in the excitation coil 21 by a motor (not shown). That is, the eddy current flaw detection probe 2 moves in the Y direction while rotating the detection coil 22.
The rotation axis P <b> 1 is orthogonal to the coil axis of the detection coil 22 and coincides with the coil axis of the excitation coil 21. Therefore, the rotation axis P1 is orthogonal to the coil surface of the exciting coil 21 and orthogonal to the inspection surface of the object T to be inspected.
In addition, although the example which rotates only the detection coil 22 was demonstrated about the eddy current flaw detection probe 2, you may comprise the excitation coil 21 and the detection coil 22 adhere | attached integrally, and may rotate both coils simultaneously. That is, you may comprise so that the eddy current test probe 2 may be rotated centering on the rotating shaft P1. In that case, since the detection coil 22 does not rotate in the excitation coil 21, it can be fixed in contact with the inner surface of the excitation coil 21.

Next, the locus of the detection coil 22 when the eddy current flaw detection probe of FIG. 1 is moved in the Y direction will be described with reference to FIG.
2A shows a plan view of the object to be inspected and the eddy current flaw detection probe, FIG. 2B shows the width of the detection coil of the eddy current flaw detection probe 2, and FIG. 2C shows the eddy current. It is a figure explaining the locus | trajectory (position) of a detection coil when the flaw detection probe 2 is moved.

2A, the eddy current flaw detection probe 2 has the same configuration as the eddy current flaw detection probe 2 in FIG. In the eddy current flaw detection probe 2, the rotation axis P1 of the detection coil 22 moves along the line L in the Y direction. During the movement, the detection coil 22 rotates clockwise (arrow direction) about the rotation axis P1. The width of the detection coil 22 (the width in the winding direction parallel to the inspection surface of the inspection object T) is W1 as shown in FIG. On the inspection surface of the inspected object T, a flaw F1 parallel to the line L, a flaw F2 orthogonal to the line L, a flaw F3 of 135 degrees, and a flaw F4 of 45 degrees are processed and formed. The inspection object T is a steel plate having a thickness of 9 mm, and the sizes of the scratches F1 to F4 are 0.2 mm wide, 1 mm deep, and 5 mm long.
The detection sensitivity of the detection coil 22 with respect to the scratches F1 to F4 is highest when the winding of the detection coil 22 is parallel to the longitudinal direction of the scratch, and is lowest when it is orthogonal.

In FIG. 2C, the trajectory indicates 1.5 rotations of the detection coil 22, the solid line with an arrow indicates the detection coil 22, and S indicates the eddy current flaw detection probe 2 while the detection coil 22 rotates once. Indicates the distance (movement distance) to move in the Y direction. The detection coil 22 is provided with an arrow for the sake of convenience in order to make it easy to understand the state of rotation. Further, the detection coil 22 (solid line with an arrow) is intermittently described at intervals of 30 degrees of rotation angle, but the rotation angle actually changes continuously.
As shown in FIG. 2C, the detection coil 22 moves in a band-shaped range having a width W1 in the Y direction while changing the angle (rotation angle) with respect to the line L. Therefore, even when there are scratches in various directions in the range of the width W1 of the inspection object T, such as scratches F1 to F4 in FIG. 2A, those scratches can be detected.
The pattern of the locus of the exciting coil 2 is different between the upper and lower sides (both sides) of the line L through which the rotation axis P1 passes, the upper pattern becomes wider in the Y direction, and the lower pattern becomes narrower than the upper side. When the rotation direction of the exciting coil 22 is reversed (counterclockwise), the upper and lower patterns are reversed as will be described later.

  In FIG. 2 (c), the upper trajectory alternately exists so that the region E3 through which the arrow side of the detection coil passes and the region E4 through which the non-arrow side passes are overlapped, and the region E3 and the region E4 are divided into two in the Y direction. Is shifted by one rotation (180 degrees). Similarly, on the lower side, the region through which the arrow side of the detection coil passes and the region through which the non-arrow side passes are alternately present. However, the lower overlap is smaller than the upper overlap. And in the overlap part of the area | region E3 and the area | region E4, since the detection coil 22 of both areas cross | intersects, even if the cracks F1-F4 are orthogonal to the detection coil 22 of the area | region E3, for example, the detection coil 22 of the area | region E4 Intersect at an angle other than a right angle. Therefore, scratches can be detected by a detection coil in at least one of the region E3 and the region E4, so that scratches in all directions can be detected.

  Since the lower arrow side area and the non-arrow side area only partially overlap in the area E2, the detection accuracy of the scratches is lower than the upper side, and the scratches exist only in the region E2. In the case of a scratch, it may not be detected. However, even in the lower region, if the movement distance S is reduced, the overlap increases and the detection accuracy can be increased. Further, even if the region E2 is the case shown in FIG. 2C or larger than the case shown in FIG. 2C, the flaw detection width (detection width) is halved (W1 / 2) in FIG. If the scanning width is set so that the upper half area of the line L is used for flaw detection and the lower half area becomes the upper half area in the second scanning, there is no effect of the area E2, and the scratch is not affected. Can be detected.

The overlapping range of the area on the arrow side and the area on the non-arrow side changes depending on the magnitude of the movement distance S (the positional deviation in the Y direction does not change in half rotation). For example, when the moving distance S is increased, that is, when the moving speed of the eddy current flaw detection probe 2 is increased, the overlapping range is reduced, and when the moving distance S is decreased, that is, when the moving speed of the eddy current flaw detection probe 2 is decreased, the overlap is increased. The range of increases. Therefore, when the rotation speed of the detection coil 22 is the same, if the moving speed of the eddy current flaw detection probe 2 is increased too much, a flaw detection failure occurs. If the moving speed of the eddy current flaw detection probe 2 is made too slow, the detection coils in the arrow-side area and the non-arrow-side area have a small crossing angle and become nearly parallel. In an extreme case, when the movement distance S = 0, the arrow-side area and the non-arrow-side area (for example, the area E3 and the area E4) overlap and rotate at the same place without moving the eddy current flaw detection probe 2. Will be in the same state as Therefore, if the moving speed of the eddy current flaw detection probe 2 is increased too much, scratches cannot be detected.
When the moving speed of the eddy current flaw detection probe 2 is the same, if the rotation speed of the detection coil 22 is increased, the moving distance S is reduced, so that the overlapping range of the area on the arrow side and the area on the non-arrow side is increased.

3 shows a simulation result of the locus of the detection coil 22 when the eddy current flaw detection probe 2 is moved in the Y direction in FIG. 2, and FIGS. 3 (a) to 3 (d) show that the detection coil 22 rotates once. The change of the locus when the movement distance S during the change is changed is shown. FIG. 3 shows a trajectory for two rotations of the detection coil 22, and the trajectory is represented at intervals of 15 degrees of rotation angle.
3A shows the movement distance S = 0.3W1 (W1 is the width of the detection coil 22), FIG. 3B shows S = 0.5W1, FIG. 3C shows S = 0.75W1, FIG. 3D shows the locus when S = 1.0W1.

As shown in FIG. 2, when there is one detection coil of the eddy current flaw detection probe, the detection is performed between the movement distance S = 0.3W1 (FIG. 3 (a)) and S = 0.75W1 (FIG. 3 (c)). Since there is no region through which the coil does not pass, scratches can be detected without leakage in the range of the width W1 of the detection coil.
In the case of FIG. 3 (d) (movement distance S = 0.3W1), the area E1 does not indicate the detection coil, but the detection coil does not pass because it is an area corresponding to the rotation start timing of the detection coil. After half a turn, the region E2 is displayed, so that the scratch can be detected also in the case of FIG. 3D, but the detection accuracy of the lower scratch is lowered.

  When the moving distance S is further increased and the area E2 is increased, the area of the upper half of the line through which the rotation axis of the detection coil passes in FIG. 3D is affected by the area E2. It is possible to detect scratches without any problems. In FIG. 3D, a region E3 is a region through which one side of the detection coil (one radius of the detection coil) passes, and a region E4 is the other side of the detection coil (the other radius of the detection coil). It is a passing area. Note that the positions of the areas E3 and E4 are shifted by a half rotation (180 degrees) in the Y direction.

Next, the result of the flaw detection test using the eddy current flaw detection probe 2 of FIG. 2 will be described.
The exciting coil 21 of the eddy current flaw detection probe 2 used for the test is a circular nylon bobbin having an outer diameter of 13 mm and an inner diameter of 10 mm wound with 100 turns of a coated copper wire having a wire diameter of 70 μm, and the detection coil 22 has a side of 8 mm. A rectangular bobbin in which a coated copper wire having a wire diameter of 50 μm was wound 120 times was used. As the excitation signal source, an oscillator having a frequency of 1 kHz to 200 kHz and an output of about 1 V was used. In the test, the eddy current flaw detection probe 2 was moved in the Y direction while rotating at 3000 rpm, and scratches F1 to F4 in FIG. 2A were detected.

  According to the test results, the width of the detection range (flaw detection width) of the eddy current flaw detection probe 2 is about 10 mm. When the moving speed of the eddy current flaw detection probe 2 in the Y direction is in the range of 9 m / min (moving distance S = 0.3W1) to 22.5 m / min (moving distance S = 0.75W1), the flaws F1 to F4 are detected. The output was almost the same, and all scratches could be detected. When the moving speed is 30 m / min (moving distance S = 1.0 W1), if the scratch F1 deviates from the line L through which the rotation axis P1 of the detection coil 22 passes, the detection output of the scratch F1 decreases, and the moving speed is reduced. If the speed is further increased, the scratch F1 cannot be detected. Further, when the moving speed becomes slower than 9 m / min, the detection output of each scratch decreases, and when the moving speed becomes further slow, the scratch cannot be detected.

FIG. 4 shows an example in which two eddy current flaw detection probes 2 of FIG. 1 are arranged side by side and the detection coils of both eddy current flaw detection probes are rotated separately to move in the Y direction.
First, FIGS. 4A-1 and 4A-2 will be described.
The two eddy current flaw detection probes 2a and 2b are arranged close to each other such that the exciting coil 21a and the exciting coil 21b are in contact with each other as shown in FIG. 4 (a-1). It arrange | positions so that the coil surface of a detection coil may be located in a line (it arranges in a straight line form in the winding direction). That is, they are arranged so as to coincide with the direction in which the rotation axes are arranged. The eddy current flaw detection probes 2a and 2b move in the Y direction while rotating the detection coils 22a and 22b clockwise around the rotation axes P1a and P1b (arrow direction). The trajectories of the detection coils 22a and 22b are as shown in FIG. 4A-2, and the flaw detection width is twice that of a single detection coil. The number of eddy current flaw detection probes is not limited to two, and two or more can be arranged.

  4 (a-1), the third eddy current flaw detection probe is connected to the excitation coil 21a. Of the eddy current flaw detection probe 2a, 2b. It can also arrange | position so that it may contact 21b (a rotating shaft is located in the vertex of a triangle). In that case, since a third trajectory is formed between the trajectories of the detection coils of the eddy current flaw detection probes 2a and 2b, the flaw detection accuracy can be further increased. The number of eddy current flaw detection probes is not limited to two and three, and two or more can be arranged.

  FIGS. 4B-1 and 4B-2 are examples in which the rotation directions of the detection coil 22a and the detection coil 22b are reversed in FIGS. 4A-1 and 4A-2. Rotates counterclockwise (arrow direction), and the detection coil 22b rotates clockwise. In this case, the trajectory pattern of one detection coil is upside down with the trajectory pattern of the other detection coil.

FIGS. 4C-1 and 4C-2 are examples in which the coil surfaces of the detection coils 22a, 22b are arranged to be orthogonal (so that the winding directions of both detection coils are orthogonal). That is, the detection coils 22a and 22b are arranged so that their positions are shifted by 90 degrees with respect to the direction in which the rotation axes are arranged. Both the detection coils 22a and 22b rotate clockwise. In this case, the positions of the trajectories of the detection coil 22a and the detection coil 22b are shifted by a quarter rotation (90 degrees) in the Y direction.

  As described above, when two or more eddy current flaw detection probes are juxtaposed, the detection coil trajectory pattern can be obtained by reversing the rotation direction of the detection coil or changing the arrangement direction of the two detection coils. Or the position in the Y direction can be changed, and the flaw detection width can be increased. In addition, by arranging the rotation axis so as to be positioned at the vertex of the polygon, the detection accuracy of the scratch can be increased.

FIG. 5 shows an example in which two eddy current flaw detection probes are juxtaposed and both eddy current flaw detection probes are moved in the Y direction while rotating around a common rotation axis.
5A shows a plan view of the eddy current flaw detection probe, FIG. 5B shows the width of the detection coil, and FIGS. 5C-1 to 5C-4 show the locus of the detection coil. Indicates.
In FIG. 5A, the eddy current testing probe 3 includes two eddy current testing probes 31 and 32. The eddy current testing probes 31 and 32 have the same configuration as the eddy current testing probe 2 of FIG. It consists of an excitation coil 311 and a detection coil 312, and an excitation coil 321 and a detection coil 322. The eddy current flaw detection probes 31 and 32 are arranged around the rotation axis P2 by being shifted by 180 degrees (two wings are arranged around the rotation axis P2), and the excitation coils 311 and 321 are arranged on the rotation axis P2. It is arranged so as to make contact or substantially contact. The detection coils 312 and 322 are arranged so that the coil surfaces of both detection coils are aligned on the same plane (aligned in a straight line in the winding direction). The eddy current flaw detection probe 3 moves in the Y direction while rotating around the rotation axis P2. The rotation axis P2 is parallel to the coil axes of the excitation coils 311 and 321 and is located at the contact point of both excitation coils.

The number of eddy current flaw detection probes constituting the eddy current flaw detection probe 3 is not limited to two, and two or more eddy current flaw detection probes can be arranged.
In FIG. 5B, the widths of the detection coils 312 and 322 are each W1, and the width W2 of the detection coil of the eddy current flaw detection probe 3 is about 2W1.

The trajectories of the detection coils 312 and 322 when the eddy current flaw detection probe 3 is moved in the Y direction are as shown in FIGS. 5 (c-1) to (c-4). 5 (c-1) to 5 (c-4), the detection coil 312 is indicated by a solid line, and the detection coil 322 is indicated by a broken line.
5 (c-1) to (c-4), FIG. 5 (c-1) shows the movement distance S = 0.75W2, FIG. 5 (c-2) shows S = 1.0W2, and FIG. c-3) shows a locus when S = 1.5W2, and FIG. 5C-4 shows a locus when S = 2.0W2.

When there are two detection coils of the eddy current flaw detection probe as shown in FIG. 5A, the movement distance S = 0.75W2 (FIG. 5C-1) to S = 1.5W2 (FIG. 5C-3). )), A region through which the detection coil does not pass does not occur, so that a flaw can be detected without omission in the range of the width W2 of the detection coil.
In the case of FIG. 5C-4 (moving distance S = 2.0W2), the detection coil is not shown, but the detection coil passes through the area E1 because it is an area corresponding to the rotation start time of the detection coil. However, after half a turn, it becomes like the region E2, so that the scratch can be detected also in the case of FIG. 5C-4, but the detection accuracy of the lower scratch is lowered. When the movement distance S is further increased and the region E2 is increased, the influence of the region E2 can be obtained by using the upper half region of the line L through which the rotation axis of the detection coil passes in FIG. Scratches can be detected without receiving any damage. In FIG. 5C-4, an area E3 is an area through which the detection coil 322 passes, and an area E4 is an area through which the detection coil 312 passes. Further, the positions of the areas E3 and E4 are shifted by a half rotation (180 degrees) in the Y direction.

Next, a result of a flaw detection test using the eddy current flaw detection probe 3 of FIG.
The two eddy current flaw detection probes 31 and 32 constituting the eddy current flaw detection probe 3 have the same configuration as that of the eddy current flaw detection probe 2 in FIG. 1, and scratches F1 to F4 with respect to the object T in FIG. Was detected. The excitation signal source used was the same as that used in the test of the eddy current flaw detection probe of FIG. 2, and the eddy current flaw detection probe 3 was rotated at 2000 rpm.

  According to the test results, the flaw detection width of the eddy current flaw detection probe 3 is about 20 mm. When the moving speed in the Y direction of the eddy current flaw detection probe 3 is in the range of 15 m / min (moving distance S = 0.75W2) to 30 m / min (moving distance S = 1.5W2), the detection outputs of the scratches F1 to F4 are All the scratches could be detected. When the moving speed is 40 m / min (moving distance S = 2.0 W2), if the scratch F1 deviates from the line L through which the rotation axis P2 of the detection coil 22 passes, the detection output of the scratch F1 decreases, and the moving speed is reduced. If it becomes even faster, it can no longer be detected. Further, when the moving speed becomes slower than 15 m / min, the detection output decreases, and when the moving speed becomes further slower, scratches cannot be detected.

FIG. 6 shows an example in which two detection coils are arranged in one excitation coil.
FIGS. 6A-1 and 6A-2 are examples in which two detection coils are rotated about their respective rotation axes. FIGS. 6B-1 and 6B-2 are two examples. This is an example in which one detection coil rotates around one rotation axis. FIGS. 6C-1 and 6C-2 are examples in which two detection coils are arranged so that the winding directions of the two detection coils are orthogonal to each other.

First, FIGS. 6A-1 and 6A-2 will be described.
In the eddy current flaw detection probe 4 of FIG. 6 (a-1), the detection coils 42a and 42b are arranged in a rectangular excitation coil 41 so that the coil surfaces of both the detection coils are aligned on the same surface (the direction of the winding is the same). Arranged in a straight line). That is, they are arranged so as to coincide with the direction in which the rotation axes are arranged. The detection coils 42a and 42b rotate around the points P1a and P1b, respectively. FIG. 6A-2 shows an example in which an elliptical excitation coil 41 is used.

In the eddy current flaw detection probe 5 of FIG. 6B-1, detection coils 52 a and 52 b are arranged in a rectangular excitation coil 51. The detection coils 52a and 52b are arranged so as to be shifted by 180 degrees around the rotation axis P2 (arranged in a two-wing propeller shape), and are arranged so as to contact or substantially contact the rotation axis P2. The detection coils 52a and 52b are arranged so that surfaces of both detection coils are aligned on the same surface (so that the winding direction is aligned in a straight line). The eddy current flaw detection probe 5 rotates about one rotation axis P2 common to the detection coils 52a and 52b. That is, the excitation coil 51 and the detection coils 52a and 52b rotate integrally around the rotation axis P2. FIG. 6B-2 shows an example in which an elliptical excitation coil 51 is used. It is also possible to increase the excitation coil 51 and rotate only the detection coils 52a and 52b.
6 (b-1) and 6 (b-2), a third detection coil is provided outside the detection coils 52a and 52b, and a three-blade propeller is formed around the rotation axis P2 at intervals of 120 degrees, for example. It can also be arranged. In this case, since the trajectories of the three detection coils overlap in a state shifted by 120 degrees in the scanning direction, the flaw detection accuracy becomes higher. The number of detection coils is not limited to three.

In the eddy current flaw detection probe 5 of FIG. 6C-1, detection coils 52 a and 52 b are arranged in a rectangular excitation coil 51. The detection coils 52a and 52b are arranged so that the positions of the detection coils 52a and 52b are shifted by 90 degrees around the rotation axis P2 so as to be in contact with or substantially in contact with the rotation axis P2. Are arranged so that they are orthogonal to each other. The eddy current flaw detection probe 5 rotates about one rotation axis P2 common to the detection coils 52a and 52b. FIG. 6 (c-2) is an example using an elliptical excitation coil 51. Note that only the detection coils 52a and 52b can be configured to rotate.
6 (c-1) and 6 (c-2), the third and fourth detection coils are provided outside the detection coils 52a and 52b, and four blades are provided around the rotation axis P2, for example, at intervals of 90 degrees. It can also be arranged in the form of a propeller. In this case, the trajectories of the four detection coils overlap with each other while being shifted by 90 degrees in the scanning direction, so that the flaw detection accuracy becomes higher.

The trajectories of the detection coils 52a and 52b in FIGS. 6C-1 and 6C-2 are shifted in the scanning direction (Y direction) by a quarter rotation (90 degrees). In the case of FIGS. 6 (b-1) and (b-2), the rotation is shifted by a half rotation (180 degrees).
In the case of FIG. 6, since only one exciting coil is required, the structure of the eddy current flaw detection probe is simplified. Moreover, since no winding of the exciting coil is interposed between the detection coils 42a and 42b and between the detection coils 52a and 52b, both the detection coils can be brought closer to each other, and scratches between the two detection coils can be detected with high sensitivity. it can.

The structure of the eddy current test probe which concerns on the Example of this invention is shown. It is a figure explaining the locus | trajectory of a detection coil when it moves, rotating the detection coil of the eddy current test probe of FIG. FIG. 2A shows a simulation result of the trajectory of the detection coil when the detection coil of the eddy current flaw detection probe is rotated and moved. This is an example in which two eddy current flaw detection probes in FIG. 1 are juxtaposed and the detection coils of both eddy current flaw detection probes are moved while rotating separately. This is an example in which two eddy current flaw detection probes of FIG. 1 are juxtaposed and both eddy current flaw detection probes are moved while rotating around a common rotation axis. This is an example of an eddy current flaw detection probe in which two detection coils are arranged in one excitation coil. The structure of the conventional eddy current flaw detection probe is shown. It is a figure explaining the flaw detection by the eddy current flaw detection probe of FIG.

Explanation of symbols

2, 2a, 2b, 3, 31, 32, 4, 5 Eddy current flaw detection probes 21, 21a, 21b, 311, 321, 41, 51 Excitation coils 22, 22a, 22b, 312, 322, 42a, 42b, 52a, 52b Detection coils F1 to F4 Scratches P1, P1a, P1b, P2 Rotating shaft S Moving distance T Inspected object W1, W2 Coil width

Claims (4)

  An eddy current flaw detection probe having an excitation coil and a detection coil arranged in the excitation coil, the coil surface of the excitation coil and the coil surface of the detection coil being arranged so as to be orthogonal to each other, the eddy current flaw detection probe or the detection coil is An eddy current flaw detection probe that moves in the scanning direction while rotating about a rotation axis.   An excitation coil and a detection coil arranged in the excitation coil are provided, and the coil surface of the excitation coil and the coil surface of the detection coil are provided with two or more eddy current flaw detection probes arranged so as to be orthogonal to each other. The eddy current flaw detection probe is arranged around one rotation axis and moves in the scanning direction while rotating around the rotation axis.   One excitation coil and two or more detection coils arranged in the excitation coil are provided, and the coil surface of one excitation coil and the coil surfaces of two or more detection coils are arranged to be orthogonal to each other. An eddy current flaw detection probe, wherein two or more detection coils are moved in a scanning direction while rotating about a rotation axis of each detection coil.   One excitation coil and two or more detection coils arranged in the excitation coil are provided, and the coil surface of one excitation coil and the coil surfaces of two or more detection coils are arranged to be orthogonal to each other. In the eddy current flaw detection probe, the two or more detection coils are arranged around one rotation axis and move in the scanning direction while rotating around the rotation axis.

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