JP4982075B2 - Eddy current testing probe - Google Patents

Description

  The present invention relates to a penetrating eddy current flaw detection probe that is used by passing a test object through a detection coil.

As a conventional penetrating eddy current flaw probe, a penetrating eddy current flaw probe in which an upper detection coil is disposed between two exciting coils that penetrate an object to be inspected has been proposed (for example, see Patent Document 1). ).
A conventional through-type eddy current flaw detection probe will be described with reference to FIGS. In addition, the same code | symbol is used for the part common to both figures.
First, FIG. 6 will be described.

6A is a perspective view of the eddy current flaw detection probe, FIG. 6B is a cross-sectional view of the X1 portion of FIG. 6A in the arrow direction, and FIG. It is a figure for demonstrating an eddy current.
The eddy current flaw detection probe Pb includes two exciting coils Ce1 and Ce2 and a detection coil Cd wound around a bobbin 2, and a cylindrical inspection object 1 passes through the bobbin 2. When an excitation signal is applied to the excitation coils Ce1 and Ce2, a magnetic flux Mf that passes through the device under test 1 and extends in the coil axis direction of both excitation coils is generated by both excitation coils. A uniform eddy current I flowing along the windings of the exciting coils Ce1 and Ce2 is generated in the device under test 1 by the magnetic flux Mf. An electromotive force is induced in the detection coil Cd by the eddy current I. The electromotive force cancels because the electromotive force induced in the portion near the excitation coil Ce1 of the detection coil Cd and the electromotive force induced in the portion close to the excitation coil Ce2 have the same magnitude and reverse direction (reverse polarity). In the end, however, no detection signal is generated. When there is a scratch on the surface of the object 1 to be inspected, the uniformity of the eddy current I is locally broken at the scratch portion, so that a detection signal (scratch signal) is generated in the detection coil Cd.

  In the eddy current flaw detection probe Pb of FIG. 6, since the inspection object 1 penetrates the exciting coils Ce1 and Ce2, the magnetic flux Mf passes through the entire inspection object 1, and the eddy current I is applied to the inspection object 1. Occurs on the entire circumference. On the other hand, the detection coil Cd detects a limited range of scratches facing a part of the object 1 to be inspected, and therefore only a part of the magnetic flux Mf and the eddy current I is used for the flaw detection. Therefore, most of the magnetic flux Mf and the eddy current I are wasted in the eddy current testing probe Pb of FIG.

FIG. 7 shows an example in which the eddy current flaw detection probe shown in FIG. 6 is applied to a wide and thin (small) plate-like or strip-like inspection object.
7A is a perspective view of the eddy current flaw detection probe, FIG. 7B is a cross-sectional view of the X2 portion of FIG. 7A in the arrow direction, and FIGS. 7C-1 and 7C-2. These are sectional drawings of the X3 part of FIG.7 (b) in the arrow direction. FIG. 7D is a cross-sectional view of the same portion as FIG. 7C-1 and is a diagram for explaining a gap between the object to be inspected and the bobbin.

The eddy current flaw detection probe Pb in FIG. 7 flaws a surface (thickness surface) in the thickness direction of a wide and thin plate-like or strip-like inspection object 1 (width W, thickness t, W >> t). This is an example. The inspected object 1 includes wide surfaces (wide surfaces) 12 and 14 and thickness surfaces 11 and 13, and the thickness t is, for example, 1 mm and the width W is, for example, about 50 mm.
In the case of the eddy current flaw detection probe Pb shown in FIG. 7, the magnetic flux generated by the exciting coils Ce1 and Ce2 and the eddy current generated by the magnetic flux are the surfaces 11, 12, and 13 of the device under test 1 along the windings of both exciting coils. 14, the eddy current on the thickness surface 11 is only used for flaw detection. Therefore, in the eddy current flaw detection probe Pb in FIG. 7, the magnetic flux and eddy current contributing to flaw detection are further wasted compared to the case of the eddy current flaw detection probe in FIG.

  When the inspected object 1 is wide and thin plate-like or belt-like, when the eddy current flaw detection probe Pb is moved, the eddy current flaw detection probe Pb is moved smoothly. As shown in FIG. And gaps S1 and S2 must be provided between the wide surface and the thick surface of the device under test 1, respectively. Therefore, when one thickness surface of the inspection object 1 is in contact with the bobbin 2, the distance between the detection coil Cd and the other thickness surface of the inspection object 1 increases by the gap S1, and the detection sensitivity decreases. End up. Further, when moving the eddy current flaw detection probe Pb, it is difficult to keep the gaps S1 and S2 constant. Therefore, the detection sensitivity changes as the gaps S1 and S2 change, and the amplitude of the detection signal changes. When the amplitude of the detection signal is small, the detection accuracy decreases due to the influence of external noise other than lift-off noise.

Japanese Patent Laid-Open No. 10-170481

  The present invention has been developed in view of the above-mentioned problems of conventional eddy current flaw detection probes in which an object to be inspected penetrates an exciting coil, in particular, eddy current flaw probes used for flaw detection of wide and thin plate-shaped or band-shaped inspected objects. An object of the present invention is to provide an eddy current flaw detection probe in which the excitation magnetic flux and eddy current that do not contribute to the current are reduced to improve the flaw detection efficiency and the detection sensitivity is not lowered.

In order to achieve the object of the present invention, the eddy current flaw detection probe according to claim 1 is provided with two detection coils penetrating the object to be inspected and an upper excitation type arranged between the two detection coils. The two detection coils are differentially connected, and the object to be inspected is a plate-like body or a band-like body having a square cross section and a wide surface and a thick surface. The inspection surface of the object to be inspected is wherein the thickness plane der Rukoto.
Eddy current testing probe according to claim 2, in the eddy current testing probe according to claim 1, wherein the exciting coil, the coil axis is arranged in a direction orthogonal to the inspection surface of the inspection object Features.
Eddy current testing probe according to claim 3, in the eddy current testing probe according to claim 1, wherein the exciting coil, that coil faces are arranged in a direction orthogonal to the inspection surface of the inspection object Features.

  In the eddy current flaw detection probe according to the present invention, the upper excitation coil is arranged between the two penetration detection coils. Therefore, in the penetration eddy current flaw detection probe, the limit necessary for flaw detection of the inspection object is required. An eddy current can be generated only in a specified range, and in particular, an eddy current can be generated only on the thick and thin plate-shaped or strip-shaped object to be inspected. Therefore, the eddy current flaw detection probe according to the present invention can efficiently perform flaw detection by reducing the generation of eddy currents that do not contribute to flaw detection. In particular, the thickness surface of a wide, thin plate-shaped or strip-shaped object to be inspected can be efficiently used. Can be flawlessly detected.

  Since the eddy current flaw detection probe according to the present invention uses two detection coils, when a differential characteristic is given to the detection coil, a coil having the same winding direction or two coils having different winding directions are used. By changing the way of connecting the coils, the differential connection corresponding to the distribution of the eddy current generated by the exciting coil can be easily realized. Moreover, since the eddy current flaw detection probe of the present invention has differential characteristics, it does not generate lift noise.

In the eddy current flaw detection probe according to the present invention, the exciting coil may be arranged so that the coil axis thereof is orthogonal to the flaw detection surface of the object to be inspected. It can also be arranged so as to be orthogonal to the plane. Therefore, the eddy current flaw detection probe according to the present invention can combine the excitation coil and the detection coil in various forms, and can change various patterns of eddy current distribution.
In the eddy current flaw detection probe according to the present invention, since the excitation coil is disposed in the middle (center) between the two detection coils, the positioning of the excitation coil is facilitated, and hence the eddy current flaw detection probe is easily manufactured. Further, the interval between the two detection coil coils can be changed according to the size of the exciting coil.

  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 perspective view of the eddy current flaw detection probe, FIG. 1B is a cross-sectional view of the X2 portion of FIG. 1A in the arrow direction, and FIGS. 1C-1 and C-2. These are sectional drawings of the X3 part of FIG.1 (b) of the arrow direction. FIG.1 (d) is sectional drawing of the same part as FIG.1 (c-1), and is a figure explaining the clearance gap between a to-be-inspected object and a bobbin.

In FIG. 1, Pb is a through-type eddy current flaw detection probe, 1 is a test object, 2 is a bobbin, Ce is an excitation coil, and Cd1 and Cd2 are detection coils.
The object to be inspected 1 has a quadrangular cross section, a wide and thin (small) plate shape or a strip shape, wide surfaces (wide surfaces) 12, 14 and thickness direction surfaces (thick surfaces) 11, 13 The inspected object 1 has a thickness t of 1 mm and a width W of about 50 mm, for example, and is thinner than the width (W >> t). The thick surfaces 11 and 13 are end surfaces in the direction orthogonal to the wide surfaces 12 and 14.

The eddy current flaw detection probe Pb includes a bobbin 2, an exciting coil Ce, and detection coils Cd1 and Cd2, and the bobbin 2 has a rectangular opening through which the device under test 1 passes. The detection coils Cd1 and Cd2 are wound around the outer periphery of the bobbin 2, and the excitation coil Ce is attached to the outer periphery of the bobbin 2 so as to face the thickness surface 11 of the device under test 1. Therefore, the detection coils Cd1 and Cd2 are through-type coils, and the excitation coil Ce is a top-type coil. The exciting coil Ce is a circular or ring-shaped coil and has a magnetic core such as ferrite. The exciting coil Ce may be square or may not have a magnetic core.
The two detection coils Cd1 and Cd2 are arranged at a predetermined interval, and the excitation coil Ce is arranged in the middle (center) between the detection coil Cd1 and the detection coil Cd2. The exciting coil Ce has its coil axis (axis passing through the center of the coil) orthogonal to the thickness surface 11 (inspection surface) of the object to be inspected 1 or the coil surface (surface surrounded by the windings). It is arranged so as to be parallel to the surface.

The detection coils Cd1 and Cd2 use coils having the same number of turns and are differentially connected to a circular eddy current generated by the excitation coil Ce as will be described later. That is, the detection coils Cd1 and Cd2 use two coils having the same winding direction and connect the winding end of one detection coil and the winding start of the other detection coil. When the winding directions of the detection coils Cd1 and Cd2 are different, the winding ends of the detection coils or the winding starts are connected to each other. The detection coils Cd1 and Cd2 output a difference between electromotive forces induced in both detection coils by an eddy current generated by the excitation coil Ce as a detection signal.
The eddy current flaw detection probe Pb moves along the inspection object 1 while fixing the inspection object 1, or moves the inspection object 1 while fixing the eddy current inspection probe Pb, and the inspection object 1 The thick surface 11 is flaw-detected.

  When the eddy current flaw detection probe Pb applies an excitation signal to the excitation coil Ce, the excitation coil Ce generates a magnetic flux in the coil axis direction (direction perpendicular to the thickness surface 11). As will be described later, the magnetic flux generates an eddy current that mainly flows along the winding of the exciting coil Ce on the thickness surface 11 of the device under test 1, but does not occur on other surfaces than the thickness surface 11. That is, since the eddy current flaw detection probe Pb only generates an eddy current on the thickness surface 11 of the inspection object 1 even when an excitation signal is applied to the excitation coil Ce, the eddy current that does not contribute to flaw detection is very small. And efficient flaw detection becomes possible. Therefore, the eddy current flaw detection probe Pb is suitable for flaw detection on the thick surface 11 of a wide and thin plate-like or strip-like inspection object.

  In order to make the eddy current flaw detection probe Pb move smoothly, gaps S1 and S2 are provided between the bobbin 2 and the wide surface and the thick surface of the object 1 to be inspected as shown in FIG. However, since the exciting coil Ce is attached at a position facing the thickness surface 11 (inspection surface) of the object 1 to be inspected, the magnetic flux generated by the exciting coil Ce is concentrated on the thickness surface 11 and mainly the thickness surface 11. Generate eddy currents. Therefore, the eddy current flaw detection probe Pb can detect flaws with a stable detection sensitivity with little influence of the gaps S1 and S2.

  As described above, the eddy current testing probe Pb in FIG. 1 is a through type eddy current testing probe Pb by making the detection coils Cd1 and Cd2 through-type and the exciting coil Ce into a top-type (non-through-type). However, since the excitation magnetic flux can be concentrated on the thickness surface 11 (inspection surface) of the object to be inspected 1 and an eddy current can be generated only on the thickness surface 11, efficient excitation and flaw detection with stable detection sensitivity are possible. Can do. Further, since the exciting coil Ce is disposed in the middle (center) between the two detection coil coils Cd1 and Cd2, the exciting coil Ce can be easily positioned and the eddy current flaw detection probe Pb can be easily manufactured. The distance between the detection coils Cd1 and Cd2 can be changed in accordance with the size of the excitation coil Ce.

Next, the eddy current of the eddy current flaw detection probe of FIG. 1 will be described with reference to FIG.
2A shows the positional relationship between the excitation coil, the detection coil, and the flaw on the thickness surface of the object to be inspected. FIGS. 2B-1 to 2B-4 and FIG. An eddy current when the flaw detection probe is moved along the inspection object is shown.

  In FIG. 2A, the flaw F on the thickness surface 11 of the inspection object 1 is located away from the excitation coil Ce and the detection coils Cd1 and Cd2 of the eddy current flaw detection probe, and the coil axis of the detection coils Cd1 and Cd2 Long scratches in the orthogonal direction. When an excitation signal is applied to the excitation coil Ce in this state, a circular eddy current I that flows along the winding of the excitation coil Ce is generated as shown in FIG. In the detection coils Cd1 and Cd2, an electromotive force is induced by a component of the eddy current I in a direction parallel to the winding of the detection coils Cd1 and Cd2. Since the direction of the eddy current I is reversed on the detection coil Cd1 side and the detection coil Cd2 side, the electromotive forces of both detection coils are the same in magnitude and in opposite directions (reverse polarity). Since they are differentially connected, they cancel each other and no detection signal (scratch signal) is generated.

  When the eddy current flaw detection probe is moved from the position of FIG. 2 (b-1) in the direction of the arrow Y and moved to the position of FIG. 2 (b-2), that is, the position immediately after the scratch F passes through the detection coil Cd2, The uniformity of the eddy current I is locally broken by the scratch F, and part of the eddy current I flows along the scratch F, and eddy currents i1 and i2 are generated. An electromotive force is induced in the detection coils Cd1 and Cd2 by the eddy currents I, i1 and i2, but the scratch F is biased from the middle of the detection coils Cd1 and Cd2 to the detection coil Cd2 side. The electromotive forces to be produced are different in size. Therefore, a detection signal is generated.

The position of the eddy current flaw probe from FIG. 2 (b-2) to the position of FIG. 2 (b-3), that is, the scratch F is in the middle (center) between the detection coil Cd1 and the detection coil Cd2, that is, the position just below the excitation coil Ce. Since the magnitudes of the electromotive forces of the detection coils Cd1 and Cd2 are the same, they cancel each other and no detection signal is generated.
When the eddy current flaw detection probe is moved from the position of FIG. 2 (b-3) to the position of FIG. 2 (b-4), that is, the scratch F is moved to a position immediately before the detection coil Cd1, the scratch F is detected by the detection coils Cd1 and Cd2. Since it is biased from the middle toward the detection coil Cd1, the magnitudes of the electromotive forces induced in the two detection coils are different. Therefore, a detection signal is generated.

  FIG. 2C shows an example in which the scratch F is long in the direction of the coil axis of the detection coils Cd1 and Cd2, and the scratch F is in the middle of the detection coil Cd1 and the detection coil Cd2, that is, directly below the excitation coil Ce. . In the case of FIG. 2C, part of the eddy current I flows along the scratch F, and the eddy currents i3 and i4 flow through the end of the scratch F. Therefore, the detection coil Cd1 is generated by the eddy currents i3 and i4. , Cd2 is induced, but scratch F is in the middle of the detection coils Cd1 and Cd2, so the electromotive forces of both detection coils are the same in magnitude and reverse in direction (reverse polarity). Therefore, no detection signal is generated. When the eddy current flaw detection probe is moved from the position shown in FIG. 2 (c) and the scratch F is biased toward the detection coil Cd1 or the detection Cd2, the eddy currents i3 and i4 have different sizes. The electromotive force is different in magnitude. Therefore, a detection signal is generated.

  As described above, when the eddy current flaw detection probe is moved along the inspected object 1, if there is a flaw F on the thickness surface 11 of the inspected object 1, the flaw F can be detected. The detection coils Cd1 and Cd2 are configured to be differentially connected so that no detection signal is generated when there is no flaw F on the thickness surface 11 (on the inspection surface). Even if the distance (lift-off) of the device under test 1 changes, lift-off noise does not occur.

FIG. 3 shows an example in which excitation coils are arranged on two thickness surfaces.
FIG. 3A shows a side view of the eddy current flaw detection probe through which the inspection object passes, and FIG. 3B shows a developed plan view of the inspection object 1.
The basic configuration of the eddy current flaw detection probe Pb in FIG. 3A is the same as that in FIG. 1, but an excitation coil Cea that opposes the thickness surface 11 of the device 1 to be inspected is disposed and the thickness surface 13 is opposed. The difference between the exciting coil Ceb and the eddy current flaw detection probe shown in FIG.

When an excitation signal is applied to the excitation coil Cea and the excitation coil Ceb, an eddy current Ia is generated on the thickness surface 11 of the device under test 1 and an eddy current Ib is generated on the thickness surface 13 as shown in FIG.
If there is a scratch on both the thickness surface 11 and the thickness surface 13 of the device under test 1 or one of the surfaces, an electromotive force is induced in the detection coils Cd1 and Cd2, and a detection signal is generated. Accordingly, the eddy current flaw detection probe Pb shown in FIG. 3A can simultaneously detect flaws on the thickness surface 11 and the thickness surface 13 of the inspection object 1. When it is necessary to determine whether the detected flaw is a flaw on the thick surface 11 or the thick surface 13, the exciting coil Cea at the position where the detection signal (flaw signal) of the device under test 1 is generated. This can be determined by applying an excitation signal only to one of the excitation coils Ceb and performing flaw detection again.

  4 and 5 show a case where a square coil is used as the exciting coil in the eddy current flaw detection probe shown in FIG. 1, and the coil surface of the exciting coil is orthogonal to the thickness surface (inspected surface) of the object to be inspected (coil axis). Is arranged parallel to the inspection surface). 4 and 5 show examples of eddy current flaw detection probes using so-called tangential coils as exciting coils. The excitation coil is not limited to a quadrangle, and may be a circle or a triangle.

First, FIG. 4 will be described.
FIG. 4A shows the positional relationship between the excitation coil, the detection coil, and the scratch on the thickness surface of the object to be inspected, and FIG. 4B shows a side view of the excitation coil. 4 (c-1) to 4 (c-4) show eddy currents generated when the eddy current flaw detection probe is moved along the inspection object in FIG. 4 (a).

  In FIG. 4A, the exciting coil Ce is arranged in a direction in which the coil axis is parallel to the coil axis of the detection coils Cd1 and Cd2 (or in a direction in which the winding of the excitation coil is parallel to the winding of the detection coil). The scratch F is a scratch that is long in the direction orthogonal to the coil axes of the detection coils Cd1 and Cd2. The detection coils Cd1 and Cd2 are differentially connected to the eddy current generated by the exciting coil Ce. That is, the detection coils Cd1 and Cd2 have the same number of turns and different winding directions, and the winding end of one detection coil and the winding start of the other detection coil are connected. The detection coils Cd1 and Cd2 connect the winding ends of the two detection coils or the winding starts when the winding directions are the same. The exciting coil Ce is a square coil as shown in FIG.

  In FIG. 4A, when an excitation signal is applied to the excitation coil Ce, a uniform eddy current I flowing along the winding is generated in the vicinity of the excitation coil Ce as shown in FIG. 4C-1. The eddy current induces an electromotive force in the detection coils Cd1 and Cd2. Since the detection coils Cd1 and Cd2 have different winding directions, the electromotive forces of the two detection coils are the same in magnitude and in opposite directions (reverse polarity), and the two detection coils are differentially connected. However, no detection signal (scratch signal) is generated.

In FIG. 4 (c-1), when the eddy current flaw detection probe is moved in the direction of arrow Y and moved to the position of FIG. 4 (c-2), the eddy current I is locally ununiform due to scratch F. Part of it flows along the scratch F, and an eddy current i5 is generated. Since the scratch F is biased toward the detection coil Cd2, the magnitudes of the electromotive forces of the detection coils Cd1 and Cd2 are different. Therefore, a detection signal is generated.
When the eddy current flaw detection probe is moved from the position shown in FIG. 4 (c-2) to the position shown in FIG. 4 (c-3), that is, when the scratch F is located between the detection coils Cd1 and Cd2 (below the excitation coil Ce), The electromotive forces of the detection coils cancel each other because they have the same magnitude, and no detection signal is generated.
When the eddy current flaw detection probe is moved from the position shown in FIG. 4 (c-3) to the position shown in FIG. 4 (c-4), the scratch F is biased toward the detection coil Cd1, so the electromotive forces of the detection coils Cd1 and Cd2 are The size is different. Therefore, a detection signal is generated.

  In the case of FIG. 4, the exciting coil Ce uses a tangential coil, and its winding is arranged in a direction parallel to the windings of the detection coils Cd1 and Cd2, so that the interval in the coil axis direction of both detection coils is reduced. be able to.

Next, FIG. 5 will be described.
FIG. 5A shows the positional relationship between the exciting coil, the detection coil, and the flaw on the thickness surface of the object to be inspected. FIGS. 5B-1 to 5B-4 are vortices in FIG. The eddy current which generate | occur | produces when an electric current flaw detection probe moves along to-be-inspected object is shown.
In FIG. 5A, two excitation coils Cec and Ced have their coil axes orthogonal to the coil axes of the detection coils Cd1 and Cd2 (or the excitation coil windings are orthogonal to the detection coil windings). The scratch F is a scratch long in the direction orthogonal to the coil axes of the detection coils Cd1 and Cd2. The detection coils Cd1 and Cd2 have the same number of turns and the same winding direction, and are differentially connected to the eddy current generated by the excitation coils Cec and Ced. That is, the winding end of one detection coil and the winding start of the other detection coil are connected. When the winding directions of the detection coils Cd1 and Cd2 are different, the winding ends of the detection coils or the winding starts are connected to each other.

The two exciting coils Cec and Ced have the same number of turns and different winding directions, and connect the winding end of one detection coil and the winding start of the other detection coil. One excitation signal source is common to the excitation coils Cec and Ced. When the winding directions of the exciting coils Cec and Ced are the same, the winding ends of the two detection coils are connected to each other.
In FIG. 5A, when an excitation signal is applied to the excitation coils Cec and Ced, as shown in FIG. 5B-1, the uniform current flows in the reverse direction along the winding in the vicinity of the excitation coils Cec and Ced. Eddy currents Ic and Id are generated. Since the electromotive forces induced in the detection coils Cd1 and Cd2 by the eddy currents Ic and Id are reversed in direction, they cancel each other and no detection signal (scratch signal) is generated.

  5 (b-1), when the eddy current flaw detection probe is moved in the direction of arrow Y and moved to the position of FIG. 5 (b-2), the eddy currents Ic and Id are locally uniform due to the scratch F. Collapses, part of which flows along the scratch F, and eddy currents i6 and i7 are generated. Since the scratch F is biased toward the detection coil Cd2, the magnitudes of the electromotive forces of the detection coils Cd1 and Cd2 are different. Therefore, a detection signal is generated.

When the eddy current flaw detection probe is moved from the position of FIG. 5 (b-2) to the position of FIG. 5 (b-3), that is, the scratch F is in the middle of the detection coils Cd1 and Cd2 (below the excitation coils Cec and Ced). Since the scratch F is located in the middle of the detection coils Cd1 and Cd2, electromotive forces having the same magnitude are generated in both the detection coils. Therefore, the electromotive forces of the detection coils Cd1 and Cd2 cancel each other and no detection signal is generated.
When the eddy current probe is moved from the position shown in FIG. 5 (b-3) to the position shown in FIG. 5 (b-4), the eddy currents Ic and Id are locally uneven due to the scratch F, and a part of them is It flows along the scratch F, and eddy currents i6 and i7 are generated. Since the scratch F is biased toward the detection coil Cd1, the magnitudes of the electromotive forces of the detection coils Cd1 and Cd2 are different. Therefore, a detection signal is generated.

  In the eddy current flaw detection probe of the above embodiment, the excitation coil can be arranged so that its coil axis is orthogonal to the flaw detection surface of the object to be inspected. It can also be arranged so as to be orthogonal to the flaw detection surface. Therefore, the eddy current flaw detection probe of the above embodiment can combine the exciting coil and the detection coil in various forms, and can generate eddy currents having various distribution patterns. Further, the eddy current flaw detection probe of the above embodiment uses two coils as detection coils, and changes the connection method of coils having the same winding direction or different winding directions, so that the difference corresponding to the distribution pattern of the eddy current is obtained. Dynamic connection can be realized.

1 shows a configuration of an eddy current flaw detection probe according to an embodiment of the present invention, and shows an example in which an exciting coil is arranged so that its coil axis is orthogonal to an inspection surface. The eddy current of the eddy current flaw detection probe of FIG. 1 is shown. An example in which two exciting coils are provided in the eddy current flaw detection probe of FIG. The eddy current flaw probe shown in FIG. 1 shows an eddy current when a tangential coil is used as an exciting coil and the winding is arranged in parallel with the winding of a detection coil. 1 shows an eddy current when a tangential coil is used as an exciting coil in the eddy current flaw detection probe of FIG. 1 and the winding is arranged so as to be orthogonal to the winding of the detection coil. The structure of the conventional eddy current flaw detection probe is shown, and the example in case a to-be-inspected object is cylindrical shape is shown. The structure of the conventional eddy current flaw detection probe is shown, and the example in case a to-be-inspected object is plate shape is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inspected object 11-14 Wide surface, thickness surface of to-be-inspected object 2 Bobbin Ce, Cea-Ced Excitation coil Cd1, Cd2 Detection coil F Scratches I, Ic, Id, i1-i7 Eddy current Pb Eddy current flaw probe S1, S2 gap

Claims (3)

It consists of two detection coils that pass through the object to be inspected and an upper excitation coil disposed between the two detection coils, and the two detection coils are differentially connected . section is a plate-like body or a strip having a wide surface and thickness surface in square, the inspection surface of the inspection object is an eddy current flaw detection probe according to claim der thickness surface Rukoto. In eddy current testing probe according to claim 1, wherein the exciting coil, an eddy current flaw detection probe, wherein the coil axis is arranged in a direction orthogonal to the inspection surface of the inspection object. In eddy current testing probe according to claim 1, wherein the exciting coil, an eddy current flaw detection probe, wherein the coil plane is disposed in a direction orthogonal to the inspection surface of the inspection object.

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