JP2014066688A - Eddy current flaw detection probe, and eddy current flaw detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an eddy current flaw detection probe and an eddy current flaw detection device, capable of accurately detecting a flaw in an inspection surface of a conductor.SOLUTION: An eddy current flaw detection probe 20 of the present invention includes: a first exciting coil 21 disposed so that the coil surface is parallel with an inspection surface 31 of a conductor 30; a second exciting coil 22 that is disposed at a position adjacent to the first exciting coil 21 in the direction along the inspection surface 31 so that the coil surface is parallel with the inspection surface 31 and is wound in the reverse winding direction to that of the first exciting coil 21; and a detection coil 23 disposed between the first exciting coil 21 and second exciting coil 22 so that the coil surface is orthogonal to the inspection surface 31 and the coil surface is parallel with the straight line passing a center P1 of the first exciting coil 21 and a center P2 of the second exciting coil 22.

Description

  The present invention relates to an eddy current flaw detection probe used for inspection of a flaw on an inspection surface of a conductor, and an eddy current flaw detection apparatus including the eddy current flaw detection probe.

  As an example of an inspection method for detecting a flaw on a conductor inspection surface (conductor surface), an eddy current flaw detection method is known. In this eddy current flaw detection method, an eddy current is generated inside a conductor by a magnetic flux generated by an alternating current flowing in an exciting coil, and a change in reaction magnetic flux caused by a change in eddy current due to a flaw on the inspection surface of the conductor is detected by a detection coil. In this way, the presence or absence of a flaw on the inspection surface is determined. For example, if there is a crack or the like on the inspection surface of the conductor, the flow of the eddy current changes so as to bypass the flaw, so that the reaction magnetic flux generated by the eddy current also changes. As a result, the voltage induced in the detection coil by the reaction magnetic flux also changes, so that the presence or absence of a flaw on the inspection surface can be determined from the change in the voltage induced in the detection coil.

  As an example of an eddy current flaw detection probe used in such an eddy current flaw detection method, an eddy current called a Θ type probe in which a detection coil whose coil surface is perpendicular to the inspection surface is arranged inside the excitation coil whose coil surface is parallel to the inspection surface. A flaw detection probe and a eddy current flaw detection apparatus including the eddy current flaw detection probe are known (see, for example, Patent Document 1 or 2).

JP 2003-240762 A JP 2003-344361 A

  However, the eddy current flaw detection probe of the above prior art has a structure in which the detection probe is arranged inside the excitation coil, and the magnetic flux generated by the excitation coil is parallel to the detection coil surface. No voltage is induced in. In other words, in the above-described prior art eddy current flaw detection probe, no voltage is always induced in the detection coil, but since the actual detection coil is wound in a finite length solenoid, the detection coil surface is completely parallel to the magnetic flux generated by the excitation coil. Even if there is no flaw on the detection surface of the conductor, it is minute but voltage induction is unavoidable, so the presence or absence of flaws on the inspection surface is determined from the change in voltage induced in the detection coil. There is a problem that it is difficult to detect extremely small flaws with high accuracy.

  In the above-described prior art eddy current flaw detection probe, for example, an iron core made of a magnetic material such as a ferrite core is inserted into a detection coil or an excitation coil, thereby increasing the detection sensitivity of the induced voltage in the detection coil. This is extremely difficult due to the structure in which the detection probe is arranged. In other words, the eddy current flaw detection probe of the above prior art cannot use an iron core made of a magnetic material such as a ferrite core that controls the flow of magnetic flux due to its structural limitations, and increases the detection sensitivity of the detection coil to detect flaws on the inspection surface of the conductor. There is a problem that it is difficult to improve accuracy.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an eddy current flaw detection probe and an eddy current flaw detection apparatus that can detect a flaw on a test surface of a conductor with high accuracy.

<First Aspect of the Present Invention>
A first aspect of the present invention is adjacent to a first excitation coil arranged so that a coil surface is parallel to an inspection surface of a conductor, and a direction along the inspection surface with respect to the first excitation coil. The coil surface is arranged at a position so that the coil surface is parallel to the inspection surface and wound in the winding direction opposite to that of the first excitation coil, and the coil surface with respect to the inspection surface. Arranged between the first excitation coil and the second excitation coil so that the coil surfaces are parallel to a straight line that is orthogonal and passes through the center of the first excitation coil and the center of the second excitation coil. And an eddy current flaw detection probe.

  Here, the “coil surface” is an opening surface surrounded by windings of the coil, in other words, a surface orthogonal to the coil axis (coaxial axis of the coil).

  An eddy current in the direction opposite to the exciting current flows through the conductor due to the magnetic flux generated by the exciting current flowing in the first exciting coil. In addition, an eddy current in the direction opposite to the excitation current flows through the conductor due to the magnetic flux generated by the excitation current flowing in the second excitation coil. Since the second exciting coil is wound in the opposite winding direction with respect to the first exciting coil, the direction of the eddy current generated by the first exciting coil and the eddy current generated by the second exciting coil are opposite to each other. become. Therefore, in the vicinity of the boundary between the eddy current generated by the first excitation coil and the eddy current generated by the second excitation coil, a line parallel to the inspection surface and passing through the center of the first excitation coil and the center of the second excitation coil. Therefore, eddy current flows in the orthogonal direction. That is, a strong eddy current that flows in a direction that is parallel to the inspection surface and orthogonal to a straight line that passes through the center of the first excitation coil and the center of the second excitation coil is generated directly below the detection coil.

  And the reaction magnetic flux by an eddy current arises only in the direction orthogonal to the eddy current. Therefore, in the vicinity of the boundary between the eddy current generated by the first excitation coil and the eddy current generated by the second excitation coil, the reaction magnetic flux due to the eddy current becomes a magnetic flux parallel to the coil surface of the detection coil. Therefore, the magnetic flux in the direction crossing the coil surface of the detection coil becomes zero. That is, in a state where there is no flaw on the inspection surface of the conductor, the voltage induced in the detection coil is zero.

  On the other hand, in the vicinity of the boundary between the eddy current generated by the first exciting coil and the eddy current generated by the second exciting coil, when there is a flaw on the inspection surface of the conductor, an eddy current is generated at that portion so as to bypass the flaw. . As a result, a reaction magnetic flux in a direction intersecting the coil surface of the detection coil is generated in the flaw portion. That is, when there is a flaw on the inspection surface of the conductor, a voltage is induced in the detection coil.

  Thus, in the eddy current flaw detection probe according to the present invention, the induced voltage of the detection coil is always zero when there is no flaw on the inspection surface of the conductor, and the induced voltage is applied to the detection coil only when there is a flaw on the inspection surface of the conductor. Arise. That is, the eddy current flaw detection probe according to the present invention can determine the presence or absence of a flaw on the inspection surface of the conductor based on the presence or absence of an induced voltage generated in the detection coil. As a result, extremely small flaws can be detected with high accuracy.

  Thereby, according to the 1st aspect of this invention, the effect that the eddy current test probe which can detect the flaw of the test | inspection surface of a conductor with high precision can be provided.

<Second Aspect of the Present Invention>
A second aspect of the present invention is the eddy current flaw detection probe according to the first aspect of the present invention described above, further comprising a first magnetic body inserted into the detection coil.
In the eddy current flaw detection probe according to the present invention, since the magnetic field is zero at the center between the excitation coils forming the N pole and the S pole, an iron core made of a magnetic material such as a ferrite core is detected without disturbing the magnetic field generated by the excitation coil. Can be interpolated. By inserting an iron core made of a magnetic material such as a ferrite core into the detection coil, the magnetic permeability is increased and the magnetic flux easily passes through the detection coil. Thereby, since the detection sensitivity of the flaw on the inspection surface of the conductor can be further improved, the flaw on the inspection surface of the conductor can be detected with higher accuracy.

<Third Aspect of the Present Invention>
According to a third aspect of the present invention, in the first aspect or the second aspect of the present invention described above, the first aspect further includes a second magnetic body inserted into the first excitation coil and the second excitation coil. Is an eddy current flaw detection probe characterized by
In the eddy current flaw detection probe according to the present invention, since the magnetic field is zero at the center between the exciting coils forming the N pole and the S pole, the first iron core made of a magnetic material such as a ferrite core is not disturbed by the exciting coil. It can be inserted into the excitation coil and the second excitation coil. By inserting an iron core made of a magnetic material such as a ferrite core into the first excitation coil and the second excitation coil, the magnetic permeability increases and the magnetic flux easily passes through the first excitation coil and the second excitation coil. More magnetic flux can be concentrated on the inspection surface. Thereby, since the detection sensitivity of the flaw on the inspection surface of the conductor can be further improved, the flaw on the inspection surface of the conductor can be detected with higher accuracy.

<Fourth aspect of the present invention>
According to a fourth aspect of the present invention, there is provided an eddy current flaw detection probe according to any one of the first to third aspects of the present invention described above, and a power supply for supplying AC power to the first excitation coil and the second excitation coil. An eddy current flaw detector comprising: a device; and a voltage measuring device that measures a voltage induced in the detection coil.
According to the fourth aspect of the present invention, in the eddy current flaw detector, the same effect as any of the first to third aspects of the present invention described above can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the eddy current test probe and eddy current test device which can detect the flaw of the test surface of a conductor with high precision can be provided.

1 is a block diagram illustrating the configuration of an eddy current flaw detector according to the present invention. The top view of the eddy current flaw detection probe of 1st Example. The front view of the eddy current flaw detection probe of 1st Example. The front view of the eddy current flaw detection probe of the 1st example which illustrated typically the magnetic flux which arises by exciting current. The top view which illustrated typically the eddy current in the state in which there is no crack in a test | inspection surface. The top view which illustrated typically the eddy current in the state with a crack in a test | inspection surface. The top view of the eddy current test probe of 2nd Example. The top view of the eddy current test probe of 3rd Example. The front view of the eddy current test probe of 3rd Example. The wave form diagram of the voltage induced in the detection coil of an eddy current test probe.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In addition, this invention is not specifically limited to the Example demonstrated below, It cannot be overemphasized that a various deformation | transformation is possible within the range of the invention described in the claim.

<Configuration of eddy current flaw detector>
The configuration of the eddy current flaw detector 10 according to the present invention will be described with reference to FIG.
FIG. 1 is a block diagram illustrating the configuration of the eddy current flaw detector 10.

  An eddy current flaw detector 10 according to the present invention includes an AC power supply 11, a voltage measuring device 12, a display unit 13, and an eddy current flaw probe 20.

  The eddy current flaw detection probe 20 includes a first excitation coil 21, a second excitation coil 22, and a detection coil 23. The first excitation coil 21 and the second excitation coil 22 are coils for generating a magnetic flux due to an excitation current and thereby generating an eddy current in the conductor. The first exciting coil 21 and the second exciting coil 22 have opposite winding directions. The detection coil 23 is a coil for detecting the reaction magnetic flux generated by the eddy current flowing in the conductor.

  The AC power supply 11 as a “power supply device” supplies AC power having an arbitrary voltage and frequency to the first excitation coil 21 and the second excitation coil 22. The voltage measuring device 12 includes a voltage measuring device such as a voltmeter, and measures the voltage induced in the detection coil 23 by the reaction magnetic flux. The display unit 13 includes a display device such as a liquid crystal display, for example, and displays an induced voltage waveform of the detection coil 23 measured by the voltage measuring device 12. The control unit 14 is a known microcomputer control circuit, and controls the AC power supply 11, the voltage measuring device 12, and the display unit 13.

<First embodiment of eddy current flaw detection probe>
A first embodiment of the eddy current flaw detection probe 20 according to the present invention will be described with reference to FIGS.

FIG. 2 is a plan view of the eddy current flaw detection probe 20 of the first embodiment. FIG. 3 is a front view of the eddy current flaw detection probe 20 of the first embodiment.
The eddy current flaw detection probe 20 is disposed on the inspection surface 31 of the conductor 30 with a predetermined interval (lift-off). The first excitation coil 21 is an annular coil, and is disposed such that the coil surface is parallel to the inspection surface 31 of the conductor 30. The second excitation coil 22 is an annular coil, and is disposed at a position adjacent to the first excitation coil 21 in the direction along the inspection surface 31 so that the coil surface is parallel to the inspection surface 31. Is done. Further, the second excitation coil 22 is wound in a winding direction opposite to that of the first excitation coil 21. Therefore, the excitation current Ie2 in the direction opposite to the excitation current Ie1 flowing through the first excitation coil 21 flows through the second excitation coil 22.
The first excitation coil 21 and the second excitation coil 22 are not particularly limited to an annular coil, and may be any shape coil such as a rectangular coil. The first exciting coil 21 and the second exciting coil 22 are preferably the same shape and size, and the same number of turns and cross-sectional area.

  The coil surface of the detection coil 23 is orthogonal to the inspection surface 31, and the coil surface is parallel to a straight line passing through the center P1 of the first excitation coil 21 and the center P2 of the second excitation coil 22. Arranged between the first excitation coil 21 and the second excitation coil 22. The detection coil 23 is an annular coil in this embodiment, but may be any shape coil such as a rectangular coil.

  FIG. 4 is a front view of the eddy current flaw detection probe 20 of the first embodiment, and schematically shows the magnetic flux generated by the excitation current Ie1 and the excitation current Ie2. 5 and 6 are plan views of the eddy current flaw detection probe 20 of the first embodiment. FIG. 5 schematically illustrates eddy currents flowing through the conductor 30 when there is no flaw on the inspection surface 31, and FIG. 6 schematically illustrates eddy currents flowing through the conductor 30 when there is a flaw on the inspection surface 31. This is schematically illustrated.

  The exciting current Ie1 flowing through the first exciting coil 21 and the exciting current Ie2 flowing through the second exciting coil 22 are currents flowing in opposite directions. Therefore, a magnetic flux distribution as shown in FIG. 4 is generated in the eddy current flaw detection probe 20 and the conductor 30. Further, the direction of the magnetic flux illustrated in FIG. 4 is reversed according to the reversal of the polarity of the excitation current which is an alternating current.

  An eddy current in the direction opposite to the excitation current Ie1 flows through the conductor 30 due to the magnetic flux generated by the excitation current Ie1 flowing through the first excitation coil 21. In addition, an eddy current in a direction opposite to the excitation current flows through the conductor 30 due to the magnetic flux generated by the excitation current Ie2 flowing through the second excitation coil 22. Since the second exciting coil 22 is wound in the reverse winding direction with respect to the first exciting coil 21, the eddy current generated by the first exciting coil 21 and the eddy current generated by the second exciting coil 22 are The direction is reversed. Therefore, in the vicinity of the boundary between the eddy current generated by the first excitation coil 21 and the eddy current generated by the second excitation coil 22, the center P1 of the first excitation coil 21 and the second excitation coil 22 are parallel to the inspection surface 31. Eddy current flows in a direction perpendicular to the straight line passing through the center P2 (FIG. 5). That is, a strong eddy current that flows in a direction that is parallel to the inspection surface 31 and orthogonal to a straight line that passes through the center P1 of the first excitation coil 21 and the center P2 of the second excitation coil 22 is generated directly below the detection coil 23. .

  And the reaction magnetic flux by an eddy current arises only in the direction orthogonal to the eddy current. Therefore, in the vicinity of the boundary between the eddy current generated by the first excitation coil 21 and the eddy current generated by the second excitation coil 22, the reaction magnetic flux due to the eddy current is all a magnetic flux parallel to the coil surface of the detection coil 23. Therefore, in a state where the inspection surface 31 of the conductor 30 is not flawed, the magnetic flux in the direction intersecting the coil surface of the detection coil 23 is zero, so that the voltage induced in the detection coil 23 is zero.

  On the other hand, when there is a flaw 32 on the inspection surface 31 of the conductor 30 in the vicinity of the boundary between the eddy current generated by the first excitation coil 21 and the eddy current generated by the second excitation coil 22, the eddy current in that portion causes the flaw 32 to pass through the flaw 32. It flows in a detour (FIG. 6). As a result, a reaction magnetic flux in a direction intersecting the coil surface of the detection coil 23 is generated in the portion of the flaw 32. That is, when there is a flaw 32 on the inspection surface 31 of the conductor 30, a voltage is induced in the detection coil 23.

  In this way, in the eddy current flaw detection probe 20 according to the present invention, the induced voltage of the detection coil 23 is always zero in a state where the inspection surface 31 of the conductor 30 has no flaw 32, and only when the inspection surface 31 has the flaw 32, An induced voltage is generated in the detection coil 23. That is, the eddy current flaw detection probe 20 according to the present invention can determine the presence or absence of the flaw 32 on the inspection surface 31 based on the presence or absence of the induced voltage generated in the detection coil 23. As a result, extremely small flaws 32 can be detected with high accuracy. Therefore, according to the present invention, it is possible to provide the eddy current flaw detection probe 20 that can detect the flaw 32 of the inspection surface 31 of the conductor 30 with high accuracy.

<Second embodiment of eddy current flaw detection probe>
A second embodiment of the eddy current flaw detection probe 20 according to the present invention will be described with reference to FIG.
FIG. 7 is a plan view of the eddy current flaw detection probe 20 of the second embodiment.
In addition to the first embodiment, the eddy current flaw detection probe 20 of the second embodiment further includes a first magnetic body 24 inserted in the detection coil 23. The first magnetic body 24 has a cylindrical shape and is an iron core made of a magnetic body such as a ferrite core. The rest of the configuration of the eddy current flaw detection probe 20 is the same as that of the first embodiment, and therefore, the same components are denoted by the same reference numerals and detailed description thereof is omitted.
The first magnetic body 24 is a cylindrical magnetic body in this embodiment, but may be any shape of magnetic body such as a rectangular ferrite core.

  As described above, in the eddy current flaw detection probe 20 according to the present invention, since the detection coil 23 is disposed at a position where the magnetic field is zero between the first excitation coil 21 and the second excitation coil 22, the first magnetic body 24 is provided. It can be inserted into the detection coil 23. Then, by inserting the first magnetic body 24 into the detection coil 23, the magnetic permeability increases and the magnetic flux easily passes through the detection coil 23. Accordingly, the detection sensitivity of the flaw 32 on the inspection surface 31 of the conductor 30 can be further improved, so that the flaw 32 on the inspection surface 31 of the conductor 30 can be detected with higher accuracy.

<Third embodiment of eddy current flaw detection probe>
A third embodiment of the eddy current flaw detection probe 20 according to the present invention will be described with reference to FIGS.
FIG. 8 is a plan view of the eddy current flaw detection probe 20 of the third embodiment. FIG. 9 is a front view of the eddy current flaw detection probe 20 of the third embodiment.
In addition to the second embodiment, the eddy current flaw detection probe 20 of the third embodiment further includes a second magnetic body 25 inserted in the first excitation coil 21 and the second excitation coil 22. As illustrated, the second magnetic body 25 is substantially U-shaped, and is an iron core made of a magnetic body such as a ferrite core. More specifically, one end side of the second magnetic body 25 is inserted into the first excitation coil 21, and the other end side is inserted into the second excitation coil 22. The rest of the configuration of the eddy current flaw detection probe 20 is the same as that of the second embodiment, and therefore, the same components are denoted by the same reference numerals and detailed description thereof is omitted.

  As described above, in the eddy current flaw detection probe 20 according to the present invention, since the detection coil 23 is disposed outside the first excitation coil 21 and the second excitation coil 22, the first excitation coil 21 and the second excitation coil 22 are connected to the first excitation coil 21 and the second excitation coil 22. Two magnetic bodies 25 can be inserted. Then, by inserting the second magnetic body 25 into the first excitation coil 21 and the second excitation coil 22, the magnetic permeability is increased, and the magnetic flux easily passes through the first excitation coil 21 and the second excitation coil 22. The coil 23 can concentrate a large amount of magnetic flux. Accordingly, the detection sensitivity of the flaw 32 on the inspection surface 31 of the conductor 30 can be further improved, so that the flaw 32 on the inspection surface 31 of the conductor 30 can be detected with higher accuracy.

<Confirmation experiment>
In order to confirm the effect of the present invention, the applicants use the eddy current flaw detection apparatus 10 to check the inspection surface 31 of the conductor 30 for each of the eddy current flaw detection probes 20 of the first embodiment and the second embodiment of the present invention. An experiment was conducted to detect flaw 32.

1. Eddy current flaw detection probe 20 of the first embodiment
The first excitation coil 21, the second excitation coil 22, and the detection coil 23 are all annular coils having an inner diameter of 60 mm and an outer diameter of 60.4 mm, and a two-layer coil in which a winding having a diameter of 0.1 mm is wound 100 turns. did.

2. Eddy current flaw detection probe 20 of the second embodiment
The first excitation coil 21 and the second excitation coil 22 are annular coils having an inner diameter of 20 mm and an outer diameter of 23 mm, and are three-layer coils in which a winding having a diameter of 0.4 mm is wound by 75 turns. The detection coil 23 was a rectangular coil having an inner diameter of 1 mm × 2 mm, an outer diameter of 1.4 mm × 2.4 mm, and a length of 6 mm. The detection coil 23 was a two-layer coil in which a first magnetic body 24 made of MnZn ferrite having a width of 1 mm, a height of 2 mm, and a length of 10 mm was inserted, and a winding having a diameter of 0.1 mm was wound 100 turns.

3. Configuration of Conductor 30 and Experimental Procedure The conductor 30 was a copper plate having a thickness of about 1 mm, a slit-shaped defect having a width of about 2 mm was provided, and this was used as a flaw 32 on the inspection surface 31. The AC voltage applied from the AC power supply 11 to the first excitation coil 21 and the second excitation coil 22 was an AC voltage of about 9 V (effective value), and the frequency was 256 KHz, which is normally used in eddy current flaw detection. Then, the induced voltage waveform of the detection coil 23 was observed with the angle of the flaw 32 being 0 degrees, 45 degrees, and 90 degrees in the state where the flaw 32 was not present on the inspection surface 31 and the state where the flaw 32 was present on the inspection surface 31.

4). Experimental Results and Discussion FIG. 10 shows an induced voltage waveform of the detection coil 23 of the eddy current flaw detection probe 20. The one-dot chain line waveform is an induced voltage waveform when the angle of the flaw 32 is 0 degrees and 90 degrees, and the solid line waveform is an induced voltage waveform when the angle of the flaw 32 is 45 degrees.

  In the state where there were no flaws 32 on the inspection surface 31, only a slight high-frequency induced voltage (not shown) due to noise or the like was detected. On the other hand, when there was a flaw 32 on the inspection surface 31, an induced voltage with a frequency of 256 KHz was clearly detected when the angle of the flaw 32 was 0 degree, 45 degree, or 90 degree. Further, a higher induced voltage was detected when the angle of the scratch 32 was 45 degrees than when the angle of the scratch 32 was 0 degrees and 90 degrees. This is presumably because when the angle of the scratch 32 is 0 degree and 90 degrees, eddy currents flowing in directions that cancel each other around the scratch 32 increase.

  In the induced voltage waveform of the detection coil 23 in the eddy current flaw detection probe 20 of the first embodiment, the peak voltage when the angle of the flaw 32 is 0 degrees and 90 degrees is about ± 0.02 V, and the angle of the flaw 32 is 45. The peak voltage at the time was about ± 0.2V. On the other hand, in the induced voltage waveform of the detection coil 23 in the eddy current flaw detection probe 20 of the second embodiment, the peak voltage when the angle of the flaw 32 is 0 degree and 90 degrees is about ± 0.04 V, and the angle of the flaw 32 is The peak voltage when the angle was 45 degrees was about ± 0.4V. This is because the first magnetic body 24 is inserted into the detection coil 23 of the second embodiment, thereby increasing the magnetic permeability and making it easier for the magnetic flux to pass through the detection coil 23, so that the flaws caused by the detection coil 23 can be prevented. This is considered to be because the detection sensitivity of 32 was improved.

  Thus, it was confirmed that the eddy current flaw detection probe 20 according to the present invention can determine the presence or absence of the flaw 32 on the inspection surface 31 based on the presence or absence of the induced voltage generated in the detection coil 23. That is, according to the eddy current flaw detection probe 20 according to the present invention, it was confirmed that the effect of being able to detect the flaw 32 on the inspection surface 31 of the conductor 30 with high accuracy was obtained. In addition, an experiment was carried out to detect a flaw 32 on the inspection surface 31 while changing the lift-off (interval between the sensor and the object to be inspected). As a result, it was confirmed that the flaw 32 on the inspection surface 31 could be detected clearly even if a lift-off of about 5 mm was provided. It was done.

DESCRIPTION OF SYMBOLS 10 Eddy current flaw detector 11 AC power supply 12 Voltage measuring device 13 Display part 14 Control part 20 Eddy current flaw detection probe 21 1st excitation coil 22 2nd excitation coil 23 Detection coil 24 1st magnetic body 25 2nd magnetic body 30 Conductor 31 Inspection of conductor Surface 32 Inspection surface flaw

Claims (4)

A first excitation coil arranged such that the coil surface is parallel to the inspection surface of the conductor;
The coil surface is arranged parallel to the inspection surface at a position adjacent to the first excitation coil in the direction along the inspection surface, and wound in a winding direction opposite to that of the first excitation coil. A second exciting coil,
The first exciting coil and the first exciting coil are arranged so that the coil surface is orthogonal to the inspection surface and the coil surface is parallel to a straight line passing through the center of the first exciting coil and the center of the second exciting coil. An eddy current flaw detection probe comprising: a detection coil disposed between the second excitation coil.   The eddy current test probe according to claim 1, further comprising a first magnetic body inserted in the detection coil.   3. The eddy current flaw detection probe according to claim 1, further comprising a second magnetic body inserted in the first excitation coil and the second excitation coil. 4. The eddy current flaw detection probe according to any one of claims 1 to 3,
A power supply device for supplying AC power to the first excitation coil and the second excitation coil;
An eddy current flaw detector comprising: a voltage measuring device that measures a voltage induced in the detection coil.

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