Electromagnetic ultrasonic probe and electromagnetic ultrasonic flaw detector

Abstract

To provide an electromagnetic ultrasonic probe considered to be used under a high temperature environment such as used for monitoring high temperature piping or the like of a nuclear power plant in operation, and capable of being used under a high temperature environment and reducing the manufacturing cost.SOLUTION: An electromagnetic ultrasonic probe 10 includes a magnet 11 that forms a static magnetic field in a sample 1, and a coil 12 that generates an eddy current in the sample 1. The coil 12 includes a wound conducting wire 12a and an isolating yarn 12b being a filamentous isolator having heat resistance properties. The isolating yarn 12b is arranged between adjacent two conducting wires 12a of the wound conducting wire 12a.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an electromagnetic ultrasonic probe and an electromagnetic ultrasonic flaw detector.

Background Art

[0002] In power plants and the like, the maintenance of component equipment is important for maintaining normal operation. Therefore, the importance of the role played by non-destructive testing techniques that can inspect component equipment without destroying it is increasing.

[0003] Particularly in nuclear power plants, it is important to ensure the integrity of primary reactor equipment such as reactor pressure vessels (RPV) and recirculation system piping, and ultrasonic flaw detection tests (UT), which are one type of non-destructive testing, are being carried out.

[0004] As an ultrasonic probe used in ultrasonic flaw detection tests, an electromagnetic ultrasonic probe (EMAT: Electro Magnetic Acoustic Transducer) that can perform ultrasonic flaw detection on a test object without contact is known.

[0005] By utilizing electromagnetic effects, electromagnetic ultrasonic probes can directly generate and propagate ultrasonic waves into a test object without passing through a contact medium. In recent years, their use in high-temperature environments such as monitoring high-temperature pipes in operating nuclear power plants has been under consideration.

[0006] As an electromagnetic ultrasonic probe (electromagnetic ultrasonic flaw detection transducer) used in a high-temperature environment (specifically, flaw detection of hot slabs in the steelmaking process), Patent Document 1 discloses a device in which a heat-resistant resin is filled between insulating coils housed in a heat shielding case, the heat shielding case is covered with a ring guard, and the housing is hermetically adhered.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, since the electromagnetic ultrasonic probe of Patent Document 1 uses a special insulating coil, the manufacturing cost increases. That is, in forming the insulating coil, a polyimide insulated wire is used, a fluororesin is coated thereon to add heat resistance and voltage resistance, and further, in order to bond with the filled heat-resistant resin, it is necessary to perform plasma treatment or chemical treatment on the fluororesin-coated surface portion.

[0009] An object of the present invention is to provide an electromagnetic ultrasonic probe that can be used in a high-temperature environment and can suppress manufacturing costs.

Means for Solving the Problems

[0010] To achieve the above object, the present invention provides a magnet that forms a static magnetic field in a subject, and a coil that generates eddy currents in the subject , a first insulating film disposed between the subject and the coil, and a second insulating film disposed between the magnet and the coil, and is an electromagnetic ultrasonic probe having, having a spiral portion wound in a spiral shape on a predetermined plane wherein the coil includes a conducting wire and an insulating thread which is a filamentous insulator having heat resistance, and the insulating thread is disposed between two adjacent conducting wires of the recording conducting wire. , the diameter of the insulating thread is larger than the value obtained by subtracting the radius of the conducting wire from the distance between the first insulating film and the second insulating film .

Effects of the Invention

[0011] According to the present invention, it is possible to suppress the manufacturing cost of an electromagnetic ultrasonic probe that can be used in a high-temperature environment. Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0013] Hereinafter, with reference to the drawings, the configuration and operation of the electromagnetic ultrasonic probe according to the first to fifth embodiments of the present invention will be described. In each figure, the same reference numerals denote the same parts. Also, in each of the drawings, the directions are specified by the XYZ axes orthogonal to each other, and +X is defined as "right", -X as "left", +Y as "rear", -Y as "front", +Z as "up", and -Z as "down".

[0014] (First Embodiment) FIG. 1 is a schematic diagram showing the configuration of an electromagnetic ultrasonic flaw detector using an electromagnetic ultrasonic probe according to the first embodiment of the present invention. The electromagnetic ultrasonic flaw detector 100 is a device that detects a flaw in a test object 1, which is a high-temperature steel component used in a reactor pressure vessel (RPV), a recirculation system pipe, etc., by using an electromagnetic ultrasonic probe 10.

[0015] As shown in FIG. 1, the electromagnetic ultrasonic flaw detector 100 includes an electromagnetic ultrasonic probe 10, an ultrasonic flaw detector 20, a computing device 30, a display device 40, a storage device 50, and an input device 60.

[0016] The electromagnetic ultrasonic probe 10 is a sensor that is disposed on the surface of the test object 1, which is the object to be measured, directly generates ultrasonic waves with respect to the test object 1, and detects the ultrasonic waves that have returned from the test object 1.

[0017] The ultrasonic flaw detector 20 is a device that controls the electromagnetic ultrasonic probe 10 and records waveform signals. The ultrasonic flaw detector 20 is provided with a pulser 21 that outputs a signal to the coil 12, a receiver 22 that receives the ultrasonic waves that have returned from the test object 1, and a data recording unit 23 that records the waveform signals received by the receiver 22. Note that the data recording unit 23 is preferably configured by a recording device such as a hard disk or a memory.

[0018] The computing device 30 outputs a signal to the coil 12 by the pulser 21 and calculates and generates a flaw detection image from the waveform signals recorded by the ultrasonic flaw detector 20. For example, a PC (personal computer) can be used. The computing device 30 is provided with a ROM (Read only memory) that stores a program and a CPU (Central Processing Unit) that executes processing according to the program.

[0019] The display device 40 is a device that displays the flaw detection result calculated by the computing device 30, for example, an LCD (liquid crystal display), and displays the flaw detection image generated by the computing device 30.

[0020] The memory device 50 is a device that stores the flaw detection results calculated by the computing device 30, for example, a storage medium equipped with a RAM (Random Access Memory). In the memory device 50, the waveform data recorded in the data recording unit 23 and the flaw detection images generated by the computing device 30 are stored.

[0021] The input device 60 is a device for inputting instructions to and operating the computing device 30, for example, a keyboard or a mouse.

[0022] FIG. 2 is a perspective view showing the configuration of the electromagnetic ultrasonic probe 10 according to the first embodiment. As shown in FIG. 2, the electromagnetic ultrasonic probe 10 includes a magnet 11, a coil 12, and an insulating film 13.

[0023] The magnet 11 is a component for forming a static magnetic field in the test object 1, for example, a permanent magnet, and a magnet with high heat resistance, for example, a samarium cobalt magnet and is preferably used.

[0024] The coil 12 is a component for generating an induced current on the surface layer of the test object 1, and is preferably arranged along a plane orthogonal to the magnetization direction of the magnet 11. The coil 12 includes a plurality of turns of a conductive wire 12a and an insulating thread 12b which is a filamentous insulator with heat resistance.

[0025] The conductive wire 12a is a filamentous current conduction wire, for example, a copper wire, which is wound in a plurality of turns between the test object 1 and the magnet 11, and is electrically connected to the ultrasonic flaw detector 20 through, for example, a coaxial cable 14.

[0026] The coil 12 preferably has a spiral portion in which the conductive wire 12a is wound in a spiral shape on a predetermined plane (for example, a plane along the surface of the test object 1). Note that the number of turns of the spiral portion 12c shown in FIG. 2 is an example of the embodiment and is not limited thereto.

[0027] The insulating thread 12b is a filamentous insulator with heat resistance, for example, a thread formed of glass fiber, and is disposed between two adjacent conductors 12a of the multi-wound conductor 12a. The two adjacent conductors 12a of the multi-wound conductor 12a are insulated by the insulating thread 12b, and short circuit is suppressed.

[0028] That is, the insulating thread 12b is formed along the conductor 12a so as to keep the separation between the multi-wound conductors 12a, and short circuit between the multi-wound conductors 12a is suppressed by the insulating thread 12b.

[0029] The insulating film 13 is a first insulating film 13a disposed between the subject 1 and the coil 12 to insulate the subject 1 and the coil 12, and a second insulating film 13b disposed between the magnet 11 and the coil 12 to insulate the magnet 11 and the coil 12. The first insulating film 13a and the second insulating film 13b are preferably formed of a ceramic sheet, and more preferably formed of a glass sheet.

[0030] In the electromagnetic ultrasonic probe 10, as shown in FIG. 2, these components are arranged in the order of the magnet 11, the first insulating film 13a, the coil 12, and the second insulating film 13b from above to below (the negative z-axis direction). Note that FIG. 2 shows the configuration of the electromagnetic ultrasonic probe 10 with the intervals between the magnet 11, the first insulating film 13a, the coil 12, and the second insulating film 13b enlarged, and the intervals in the actual electromagnetic ultrasonic probe 10 are small.

[0031] Further, the coil 12 preferably has an extension portion 12d in which the conductor 12a extends from the center of the spiral portion 12c to the outer diameter side of the spiral portion 12c. The extension portion 12d is electrically connected to the coaxial cable 14.

[0032] FIG. 3 is an enlarged view of a third insulating film 13c provided between the spiral portion 12c and the extension portion 12d of the coil 12 according to the present embodiment.

[0033] As shown in FIG. 3, it is preferable that a sheet-like third insulating film 13c for insulating the conducting wire 12a of the spiral portion 12c and the extending portion 12d is provided between the spiral portion 12c and the extending portion 12d. Note that the third insulating film 13c is preferably formed of a ceramic sheet, more preferably formed of a glass sheet, in the same manner as the first insulating film 13a and the second insulating film 13b.

[0034] In FIG. 3, an embodiment of the third insulating film 13c as a sheet-like insulating film is shown. However, the present invention is not limited to this, and the third insulating film 13c may be an insulating film coated on the extending portion 12d.

[0035] FIG. 4 is a cross-sectional view taken along line A-A of FIG. 2. As shown in FIG. 4, the conducting wire 12a and the insulating thread 12b are alternately arranged between the first insulating film 13a and the second insulating film 13b. Thereby, the conducting wire 12a is insulated by the insulating thread 12b, the first insulating film 13a, and the second insulating film 13b.

[0036] FIG. 5 is a schematic cross-sectional view for explaining the relationship between the wire diameter d1 of the conducting wire 12a, the wire diameter d2 of the insulating thread 12b, and the distance D between the gaps of the first insulating film 13a and the second insulating film 13b in the electromagnetic ultrasonic probe 10 according to the present embodiment.

[0037] Using FIG. 5, the relationship between the wire diameter d1 of the conducting wire 12a, the wire diameter d2 of the insulating thread 12b, and the distance D between the gaps of the first insulating film 13a and the second insulating film 13b for suppressing a short circuit between two adjacent conducting wires 12a will be described.

[0038] If the wire diameter d1 of the conducting wire 12a, the wire diameter d2 of the insulating thread 12b, and the distance D between the gaps of the first insulating film 13a and the second insulating film 13b are the same as shown in FIG. 4, the short circuit between two adjacent conducting wires 12a can be suppressed. However, the wire diameter d1 of the conducting wire 12a is several tens of micrometers for thin ones, and the distance D between the gaps of the first insulating film 13a and the second insulating film 13b may become larger than the wire diameter d1 of the conducting wire 12a. Further, if the wire diameter d2 of the insulating thread 12b is smaller than the wire diameter d1 of the conducting wire 12a, there is a risk that two adjacent conducting wires 12a will short-circuit. Therefore, the conditions for suppressing the short circuit between two adjacent conducting wires 12a are examined below.

[0039] In order to separate two adjacent conducting wires 12a by the insulating thread 12b so that the two adjacent conducting wires 12a do not short-circuit, the insulating thread 12b may be arranged between the central points O of the cross-sections of the two adjacent conducting wires 12a.

[0040] Note that even if the insulating thread 12b is not arranged between the central points O of the cross-sections of two adjacent conducting wires 12a, if the insulating thread 12b is arranged between the two adjacent conducting wires 12a, the two adjacent conducting wires 12a may not come into contact. However, in this case, there is no insulating thread 12b between the outermost peripheral surfaces of the two adjacent conducting wires 12a that are closest to each other, and there is a risk of short circuit.

[0041] From these facts, it can be a condition for suppressing the short circuit between two adjacent conducting wires 12a that the insulating thread 12b intersects the line segment L connecting the central points O of the cross-sections of the two adjacent conducting wires 12a shown in FIG. 5.

[0042] When the above conditions are expressed as a mathematical formula using FIG. 5, the following formula (1) is obtained.

[0043]

Equation

[0044] That is, it is preferable that the wire diameter d2 of the insulating thread 12b is larger than the value (D - d1 / 2) obtained by subtracting the distance d1 / 2 from the center point O of the conducting wire 12a to the second insulating film 13b from the distance D between the first insulating film 13a and the second insulating film 13b.

[0045] Here, when calculating the case where the distance D between the first insulating film 13a and the second insulating film 13b is, for example, 1.5 times the diameter d1 of the conducting wire 12a, the relationship between the diameter d1 of the conducting wire 12a and the diameter d2 of the insulating thread 12b is expressed by the following formula (2).

[0046]

Equation

[0047] From this, it can be seen that when the distance D between the first insulating film 13a and the second insulating film 13b is 1.5 times the diameter d1 of the conducting wire 12a, the diameter d2 of the insulating thread 12b must be made larger than the diameter d1 of the conducting wire 12a.

[0048] Next, a method of generating ultrasonic waves in the subject 1 by the electromagnetic ultrasonic probe 10 according to the present embodiment will be described. FIG. 6 is a schematic cross-sectional view showing an example of a state in which a current is passed through the spiral portion 12c of the coil 12 in the electromagnetic ultrasonic probe 10 according to the present embodiment.

[0049] As shown in FIG. 6, in the electromagnetic ultrasonic probe 10, the magnet 11 is arranged such that the magnetization direction is in the z-axis direction (vertical direction), and the magnetic field is formed from the magnet 11 toward the subject 1.

[0050] Also, since the direction of the current flowing through each conducting wire 12a of the spiral portion 12c is such that the conducting wire 12a is wound in a spiral shape on a plane along the surface of the subject 1 in the spiral portion 12c as described above, the directions are opposite with the center of the spiral portion 12c as the boundary. Note that FIG. 6 shows an embodiment in which, with respect to the center of the spiral portion 12c, the current flows forward in the right-side conducting wire 12a and the current flows backward in the left-side conducting wire 12a.

[0051] By passing an electric current through the spiral portion 12c with the pulsar 21, eddy currents flowing in the opposite direction to the direction of the electric current flowing through the spiral portion 12c are generated in the surface layer of the test object 1. Then, due to the interaction between the eddy current and the magnetic field, a Lorentz force is generated in the surface layer of the test object 1.

[0052] Then, by reversing the direction of the current flowing through the spiral portion 12c over time and reversing the direction of the Lorentz force over time, ultrasonic waves are generated. At this time, the vibration of the ultrasonic waves occurs in a direction perpendicular to both the eddy current and the magnetic field, that is, in the radial direction of the spiral portion 12c (the x-axis direction in FIG. 6).

[0053] Also, the ultrasonic waves spread three-dimensionally and isotropically from the surface of the test object 1 into the test object 1. At this time, the phases of the ultrasonic waves are the same in the downward direction (the negative z-axis direction shown in FIG. 6). Therefore, the synthesized ultrasonic waves become plane waves and propagate downward in the test object 1.

[0054] The ultrasonic waves propagating downward in the test object 1 are reflected by defects (scratches and cracks) inside the test object 1 or the back surface of the test object 1, etc. The electromagnetic ultrasonic flaw detector 100 detects this reflected ultrasonic wave with the electromagnetic ultrasonic probe 10 and calculates the presence or absence of defects and the plate thickness, etc.

[0055] FIG. 7 is a cross-sectional schematic view showing an example of a state in which an induced current is generated in the spiral portion 12c of the coil 12 by ultrasonic waves in the electromagnetic ultrasonic probe 10 according to the present embodiment.

[0056] Due to the ultrasonic waves reflected from the back surface of the test object 1, displacements are generated symmetrically with respect to the center of the spiral portion 12c on the surface layer of the test object 1. (Note that FIG. 7 shows, as an example, a state in which a displacement in the right direction (the positive x-axis direction) occurs on the left side and a displacement in the left direction (the negative x-axis direction) occurs on the right side with respect to the center of the spiral portion 12c.)

[0057] In addition, the vibration of the ultrasonic wave changes over time as described above. Therefore, the direction of displacement continuously changes in the radial direction of the spiral portion 12c (the x-axis direction in FIG. 7) over time. At this time, eddy currents are generated on the surface layer of the test object 1 due to the interaction between the displacement and the magnetic field. Then, an induced current flowing in the direction opposite to the eddy current is generated in the spiral portion 12c of the coil 12 due to the eddy current generated on the surface layer of the test object 1, and is transmitted to the receiver 22.

[0058] In the above description, an embodiment has been shown in which an induced current is generated in the spiral portion 12c that generates ultrasonic waves by the reflected ultrasonic waves to detect deep flaws. However, the present invention is not limited to this embodiment, and one electromagnetic ultrasonic probe 10 may be provided with a spiral portion 12c that generates an induced current by the reflected ultrasonic waves separately from the spiral portion 12c that generates ultrasonic waves. Further, separately from the electromagnetic ultrasonic probe 10 having the spiral portion 12c that generates ultrasonic waves, an electromagnetic ultrasonic probe 10 having a spiral portion 12c that generates an induced current by the reflected ultrasonic waves may be provided.

[0059] [Effect] In the electromagnetic ultrasonic probe of the present embodiment, the coil 12 includes a plurality of wound conductive wires 12a and an insulating thread 12b that is a filamentous insulator having heat resistance, and the insulating thread 12b is disposed between two adjacent conductive wires 12a of the plurality of wound conductive wires 12a.

[0060] Therefore, in the electromagnetic ultrasonic probe 10 of the present embodiment, even if the insulating thread 12b that insulates two adjacent conductive wires of the conductive wire is placed in a high-temperature environment, there is no risk of melting like a coil that covers the conductive wire with resin, and it can be used even in a high-temperature environment. That is, in the present embodiment, since a special insulating coil is not used as in Patent Document 1, the manufacturing cost of the electromagnetic ultrasonic probe can be suppressed.

[0061] Furthermore, in the electromagnetic ultrasonic probe of Patent Document 1, an auxiliary member for cooling is used, but in the electromagnetic ultrasonic probe 10 of the present embodiment, flaw detection can be performed in a high-temperature environment without using an auxiliary member for cooling.

[0062] In addition, in the electromagnetic ultrasonic probe 10 of the present embodiment, it is preferable that the coil 12 has a spiral portion 12c in which the conductive wire 12a is wound in a spiral shape on a predetermined plane (for example, a plane along the surface of the subject 1). Thereby, since an eddy current can be generated substantially uniformly in the surface layer of the subject 1, the detection accuracy of the electromagnetic ultrasonic probe 10 can be improved.

[0063] In addition, in the electromagnetic ultrasonic probe 10 of the present embodiment, it is preferable to include a first insulating film 13a disposed between the subject 1 and the coil 12 and a second insulating film 13b disposed between the magnet 11 and the coil 12. Thereby, the coil 12 is insulated from the subject 1 and the magnet 11, and it is possible to prevent the coil 12 from being short-circuited to the subject 1 and the magnet 11.

[0064] In addition, in the electromagnetic ultrasonic probe 10 of the present embodiment, it is preferable that the diameter d2 of the insulating thread 12b is larger than a value obtained by subtracting the radius d1 / 2 of the conductive wire 12a from the distance D between the first insulating film 13a and the second insulating film 13b. Thereby, since the insulating thread 12b can be disposed between the central points O of the cross sections of two adjacent conductive wires 12a disposed between the first insulating film 13a and the second insulating film 13b, a short circuit between the two adjacent conductive wires 12a can be suppressed.

[0065] In addition, in the electromagnetic ultrasonic probe 10 of the present embodiment, the coil 12 preferably has an extending portion 12d in which the conductive wire 12a extends from the center of the spiral portion 12c to the outer diameter side of the spiral portion 12c, and a third insulating film 13c is provided between the spiral portion 12c and the extending portion 12d. Thereby, a short circuit between the spiral portion 12c and the extending portion 12d can be suppressed, and a decrease in the detection accuracy of the electromagnetic ultrasonic probe 10 can be suppressed.

[0066] In addition, in the electromagnetic ultrasonic probe 10 of the present embodiment, it is preferable that the insulating thread 12b is formed of glass fiber. Since glass fiber has excellent heat resistance, the electromagnetic ultrasonic probe 10 can be used even in a high-temperature environment.

[0067] In the electromagnetic ultrasonic probe 10 of this embodiment, it is preferable that the first insulating film 13a and the second insulating film 13b are formed of a ceramic sheet. Since the ceramic sheet is excellent in heat resistance, the electromagnetic ultrasonic probe 10 can be used even in a high-temperature environment.

[0068] Also, in the electromagnetic ultrasonic probe 10 of this embodiment, it is preferable that the magnet (magnet 11) is a samarium cobalt magnet. Since the samarium cobalt magnet is excellent in heat resistance, the electromagnetic ultrasonic probe 10 can be used even in a high-temperature environment.

[0069] (Second Embodiment) FIG. 8 is a perspective view showing the configuration of an electromagnetic ultrasonic probe according to the second embodiment of the present invention. FIG. 9 is a perspective view showing another configuration of the electromagnetic ultrasonic probe according to the second embodiment of the present invention.

[0070] The difference between the electromagnetic ultrasonic probe 210 according to this embodiment and the electromagnetic ultrasonic probe 10 according to the first embodiment is as follows. That is, the coil 211 of the electromagnetic ultrasonic probe 210 according to this embodiment is provided with a plurality of layers of spiral portions 212 in which a plurality of spiral portions 212 are stacked, and the plurality of layers of spiral portions 212 are connected so that currents in the same direction flow, and a fourth insulating film 213 is provided between two adjacent layers of the plurality of layers of spiral portions 212. Note that the fourth insulating film 213 is preferably formed of a ceramic sheet, more preferably formed of a glass sheet, like the first insulating film 13a and the second insulating film 13b.

[0071] In the thus configured plurality of layers of spiral portions 212, the fourth insulating film 213 insulates two adjacent layers of spiral portions 212 and causes each of the plurality of layers of spiral portions 12c to form a magnetic field in the same direction.

[0072] FIG. 8 shows an electromagnetic ultrasonic probe 210 having a two-layer spiral portion 212. As shown in FIG. 8, the electromagnetic ultrasonic probe 210 having a two-layer spiral portion 212 includes, from above downward (negative z-axis direction), a magnet 11, a second insulating film 13b, a first spiral portion 212a, a fourth insulating film 213, a second spiral portion 212b, and a first insulating film 13a.

[0073] In the first spiral portion 212a, a conducting wire 12a electrically connected to the coaxial cable 14 is spirally wound in a predetermined winding direction (clockwise in FIG. 8) from the outer peripheral side toward the center on a predetermined plane (for example, a plane along the second insulating film 13b). The conducting wire 12a at the center of the first spiral portion 212a extends onto the lower first insulating film 13a through a through hole 213a provided in the fourth insulating film 213 and is electrically connected to the second spiral portion 212b.

[0074] In the second spiral portion 212b, the conducting wire 12a connected to the first spiral portion 212a is spirally wound in the same winding direction (clockwise) as the first spiral portion 212a from the center toward the outer peripheral side on a predetermined plane (for example, a plane along the first insulating film 13a). As a result, currents in the same direction flow through the first spiral portion 212a and the second spiral portion 212b, forming magnetic fields in the same direction.

[0075] FIG. 9 shows an electromagnetic ultrasonic probe 210 having a three-layer spiral portion 212. As shown in FIG. 9, the electromagnetic ultrasonic probe 210 having a three-layer spiral portion 212 includes, from above downward (negative z-axis direction), a magnet 11, a second insulating film 13b, a first spiral portion 212a, a fourth insulating film 213, a second spiral portion 212b, a fourth insulating film 213, a third spiral portion 212c, and a first insulating film 13a.

[0076] In the first spiral portion 212a, the conducting wire 12a connected to the coaxial cable 14 is spirally wound in a predetermined winding direction (clockwise in FIG. 9) from the outer peripheral side toward the center on a predetermined plane (for example, a plane along the second insulating film 13b). The conducting wire 12a at the center of the first spiral portion 212a extends onto the lower fourth insulating film 213 through a through hole 213a provided at the center of the fourth insulating film 213 and is electrically connected to the second spiral portion 212b.

[0077] In the second spiral portion 212b, the conducting wire 12a electrically connected to the center of the first spiral portion 212a is spirally wound in the same winding direction (clockwise) as the first spiral portion 212a from the center toward the outer peripheral side on a predetermined plane (for example, a plane along the fourth insulating film 213). The conducting wire 12a on the outer peripheral side of the second spiral portion 212b extends onto the lower first insulating film 13a through a through hole 213b provided at the edge of the fourth insulating film 213 and is electrically connected to the third spiral portion 212c.

[0078] In the third spiral portion 212c, the conducting wire 12a electrically connected to the outer peripheral side of the second spiral portion 212b is spirally wound in the same winding direction (clockwise) as the first spiral portion 212a and the second spiral portion 212b from the outer peripheral side toward the center on a predetermined plane (for example, a plane along the first insulating film 13a). The conducting wire 12a at the center of the third spiral portion 212c is electrically connected to the coaxial cable 14 through an extension portion 12d extending to the outer diameter side of the third spiral portion 212c.

[0079] As a result, currents in the same direction flow through the first spiral portion 212a, the second spiral portion 212b, and the third spiral portion 212c, forming magnetic fields in the same direction.

[0080] In addition, when the plurality of spiral portions 212 are even layers like the two-layer spiral portion 212 shown in FIG. 8, since the two conducting wires 12a electrically connected to the coaxial cable 14 are arranged on the outer diameter side of the spiral portion 212, it is not necessary to provide the extension portion 12d and the third insulating film 13c. On the other hand, when the plurality of spiral portions 212 are odd layers like the three-layer spiral portion 212 shown in FIG. 9, since one of the two conducting wires 12a electrically connected to the coaxial cable 14 is arranged at the center of the spiral portion 212, it is necessary to provide the extension portion 12d and the third insulating film 13c.

[0081] [Effect] In the coil 211 of the electromagnetic ultrasonic probe 210 of the present embodiment, a plurality of spiral portions 212 in which a plurality of spiral portions 212 are stacked are provided, and the plurality of spiral portions 212 are electrically connected so that currents in the same direction flow. It is preferable that a fourth insulating film 213 is provided between two adjacent spiral portions 212 of the plurality of spiral portions 212. Thereby, the eddy current generated on the surface layer of the specimen 1 can be increased, and the ultrasonic wave generated in the specimen 1 can be increased, so that the detection accuracy of the electromagnetic ultrasonic probe 210 can be improved.

[0082] (Third Embodiment) FIG. 10 is a perspective view of a coil 311 according to the third embodiment of the present invention. The difference between the coil 311 according to the present embodiment and the coil 12 according to the first embodiment is that the spiral portion 312 is provided with a straight portion 313.

[0083] That is, unlike the spiral portion 12c of the coil 12 according to the first embodiment, the spiral portion 312 of the coil 311 according to the present embodiment is provided with a straight portion 313 in which the conducting wires 12a are arranged linearly.

[0084] Specifically, as shown in FIG. 10, the coil 311 according to the present embodiment is formed in an oval shape and includes two straight portions 313. Note that the coil 311 may be formed in a rectangular shape.

[0085] [Effect] Since the spiral portion 12c of Embodiment 1 does not include a straight portion 313 and is formed in a circular shape, a circular eddy current flowing in a direction opposite to the current flowing through the spiral portion 12c is generated on the surface layer of the subject 1. Since the Lorentz force is generated in a direction orthogonal to the eddy current and the magnetic field, it is generated in the radial direction of the spiral portion 12c. Further, ultrasonic waves are generated by the Lorentz force, and the vibration of the ultrasonic waves is radially excited on the surface layer of the subject 1.

[0086] On the other hand, the spiral portion 312 of the present embodiment includes a straight portion 313 in which the conducting wires 12a are arranged linearly. A linear induction current flowing in a direction opposite to the current flowing through the straight portion 313 is generated on the surface layer of the subject 1 facing the straight portion 313. Since the Lorentz force is generated in a direction orthogonal to the induction current and the magnetic field, it is generated in a direction orthogonal to the straight portion 313 on the surface layer of the subject 1. Further, ultrasonic waves are generated by the Lorentz force, and the vibration of the ultrasonic waves is excited in the range of the width L1 of the straight portion 313 in a direction orthogonal to the straight portion 313 on the surface layer of the subject 1. That is, an electromagnetic ultrasonic probe capable of obtaining a detection range in which the vibration of the ultrasonic waves is in the same direction can be manufactured.

[0087] (Fourth Embodiment) FIG. 11 is a perspective view of a coil 411 according to the fourth embodiment of the present invention. The difference between the coil 411 according to the present embodiment and the coil 311 according to the third embodiment is the number of spiral portions 412.

[0088] That is, the coil 311 according to the third embodiment includes one spiral portion 312 formed in an oval shape. On the other hand, the coil 411 according to the present embodiment includes two spiral portions 412 formed in an oval shape. The two spiral portions 412 are arranged such that straight portions 413 (a first straight portion 413a and a third straight portion 413c) are adjacent to each other on a plane. Further, the conducting wires 12a of the adjacent straight portions 413 (the first straight portion 413a and the third straight portion 413c) of the two spiral portions 412 are electrically connected, and the winding directions of the conducting wires 12a of each other are opposite. Note that the coil 411 may include two spiral portions formed in a rectangular shape.

[0089] The coil 411 according to the present embodiment will be described in detail below with reference to FIG. 11. The coil 411 includes a first spiral portion 412a, a second spiral portion 412b, a first extension portion 414a, and a second extension portion 414b.

[0090] The first spiral portion 412a includes a first straight portion 413a and a second straight portion 413b, and the second spiral portion 412b includes a third straight portion 413c and a fourth straight portion 413d.

[0091] The first spiral portion 412a and the second spiral portion 412b are arranged on the (same) plane such that the first straight portion 413a and the third straight portion 413c are adjacent to each other. The conducting wires 12a of the first straight portion 413a and the third straight portion 413c are electrically connected, and the winding directions of the conducting wires 12a of each other are opposite (in FIG. 11, the first spiral portion 412a is counterclockwise and the second spiral portion 412b is clockwise). As a result, currents in the same direction flow through the first straight portion 413a and the third straight portion 413c.

[0092] The first extension portion 414a extends from the center of the first spiral portion 412a to the outer diameter side of the first spiral portion 412a and is electrically connected to the coaxial cable 14. The second extension portion 414b extends from the center of the second spiral portion 412b to the outer diameter side of the second spiral portion 412b and is electrically connected to the coaxial cable 14.

[0093] A third insulating film 13c is provided between the first spiral portion 412a and the first extension portion 414a to insulate the first spiral portion 412a and the first extension portion 414a. A third insulating film 13c is also provided between the second spiral portion 412b and the second extension portion 414b to insulate the second spiral portion 412b and the second extension portion 414b.

[0094] [Effect] The coil 411 according to the present embodiment is provided with two spiral portions 412 formed in an oval shape. The two spiral portions 412 are arranged on the plane such that the straight portions 413 (the first straight portion 413a and the third straight portion 413c) are adjacent to each other. Further, it is preferable that the winding directions of the conducting wires 12a of each other are opposite.

[0095] As a result, since currents in the same direction flow through adjacent straight portions 413, ultrasonic vibrations are excited in a range of a vertical width Ly in a direction orthogonal to the adjacent straight portions 413 on the surface layer of the subject 1 facing the adjacent straight portions 413. That is, an electromagnetic ultrasonic probe in which a detection range of ultrasonic vibrations in the same direction can be obtained can be manufactured.

[0096] Further, since the lateral width Lx of adjacent straight portions 413 (the first straight portion 413a and the third straight portion 413c) is wider than the lateral width Lx of the straight portion 313 of the third embodiment, the detection range of the electromagnetic ultrasonic probe can be widened compared to the third embodiment.

[0097] (Fifth Embodiment) FIG. 12 is a perspective view of an electromagnetic ultrasonic probe 510 according to a fifth embodiment of the present invention. The difference between the electromagnetic ultrasonic probe 510 according to the present embodiment and the electromagnetic ultrasonic probe 10 according to the first embodiment lies in the location where the conductive wire 12a is wound a plurality of times and the winding method of the conductive wire 12a.

[0098] That is, in the coil 12 according to the first embodiment, the conductive wire 12a is wound in a spiral shape on a predetermined plane between the subject 1 and the magnet 11. On the other hand, in the coil 512 according to the present embodiment, the conductive wire 12a is wound around the magnet 511 in a spiral shape.

[0099] Next, the electromagnetic ultrasonic probe 510 according to the present embodiment will be described in detail with reference to FIG. 12. The electromagnetic ultrasonic probe 510 includes a prismatic magnet 511, an insulating film 513 covering the magnet 511, a coil 512 wound around the magnet 511 in a spiral shape via the insulating film 513, and a first insulating film 13a (not shown). Further, the coil 512 includes a conductive wire 12a wound in a spiral shape and an insulating thread 12b disposed between two adjacent conductive wires 12a. Note that the insulating film 513 is preferably formed of a ceramic sheet, more preferably formed of a glass sheet, in the same manner as the first insulating film 13a and the second insulating film 13b.

[0100] The conducting wire 12a is preferably wound around the magnet 511 in a spiral shape so as to be arranged on the surface of the magnet 511 facing the object 1. As a result, a straight portion 512a in which a plurality of conducting wires 12a are linearly arranged is formed on the surface of the magnet 511 facing the object 1, and currents in the same direction flow through the straight portion 512a.

[0101] Note that the insulating film 513 preferably covers only the surface of the magnet 511 around which the conducting wire 12a is wound. Further, the coil 512 wound around the magnet 511 in a spiral shape via the insulating film 513 may be further covered with the insulating film 513, the coil 512 may be further wound in a spiral shape, and a plurality of layers of straight portions 512a may be provided between the object 1 and the magnet 11.

[0102] [Effect] In the present embodiment, since the conducting wire 12a is wound around the magnet 511 in a spiral shape so as to be arranged on the surface of the magnet 511 facing the object 1, a straight portion 512a is formed on the surface of the magnet 511 facing the object 1. Then, currents flow in the same direction through the straight portion 512a, and Lorentz forces in the same direction are generated.

[0103] Ultrasonic waves are generated by the Lorentz force, and the vibration of the ultrasonic waves is excited in the range of the width Ly of the straight portion 512a in a direction orthogonal to the straight portion 512a on the surface layer of the object 1. Therefore, in the present embodiment, the vibration of the ultrasonic waves is excited only in one direction, and it is possible to suppress the excitation in different directions as in other embodiments. That is, an electromagnetic ultrasonic probe adapted to the shape of the object 1 can be manufactured.

[0104] Further, since the straight portion 512a can be provided so as to cover the facing surface of the magnet 511 facing the object 1, the undetected portion can be reduced. As a result, in the present embodiment, the effective detection area for effectively detecting the flaw detection portion on the facing surface of the electromagnetic ultrasonic probe facing the object 1 can be increased as compared with other embodiments, so that the ultrasonic probe can be miniaturized.

[0105] Note that the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, for part of the configuration of each embodiment, addition, deletion, or replacement with other configurations is possible.

[0106] Note that the embodiments of the present invention may also be in the following aspects. In the above embodiments, a Lorentz type ultrasonic probe that detects using the Lorentz force was shown. However, the present invention is not limited thereto, and it can also be applied to a magnetostrictive ultrasonic probe that utilizes the magnetostrictive effect of a magnetic material.

[0107] Also, the above embodiments show the basic configuration of an electromagnetic ultrasonic probe that can operate in a high-temperature environment. For example, the direction of the magnetic field generated by a magnet, the vibration direction, deflection direction of the generated ultrasonic wave, the waveform and frequency of the ultrasonic wave transmitted and received as ultrasonic flaw detection conditions, the display method of the flaw detection result, etc. are not limited. Also, each device structure or method is not limited, and it may be replaced with other structures or methods that can obtain the same effect.

Description of Reference Numerals

[0108] 1... Specimen, 10, 210, 510... Electromagnetic ultrasonic probe, 11, 511... Magnet, 12, 211, 311, 411, 512... Coil, 12a... Conductive wire, 12b... Insulating thread, 12c, 212, 312, 412... Spiral part, 212a, 412a... First spiral part, 212b, 412b... Second spiral part, 212c... Third spiral part, 12d... Extension part, 13, 513... Insulating film, 13a... First insulating film, 13b... Second insulating film, 13c... Third insulating film, 213... Fourth insulating film, 313, 413, 512a... Straight part, 100... Electromagnetic ultrasonic flaw detector

Claims

1. An electromagnetic ultrasonic probe having a magnet that forms a static magnetic field in a subject, a coil that generates eddy currents in the subject, a first insulating film disposed between the subject and the coil, and a second insulating film disposed between the magnet and the coil, wherein the coil includes a conductor having a spiral portion wound in a spiral shape on a predetermined plane, and an insulating thread that is a filamentous insulator having heat resistance, the insulating thread is disposed between two adjacent conductors of the conductor, the electromagnetic ultrasonic probe is characterized in that the diameter of the insulating thread is larger than a value obtained by subtracting the radius of the conductor from the distance between the first insulating film and the second insulating film.

2. The electromagnetic ultrasonic probe according to claim 1, wherein the coil has an extending portion in which the conductor extends from the center of the spiral portion to the outer diameter side of the spiral portion, the electromagnetic ultrasonic probe is characterized in that a third insulating film is provided between the spiral portion and the extending portion.

3. The electromagnetic ultrasonic probe according to claim 1 or 2, wherein the coil is provided with a plurality of layers of spiral portions in which a plurality of the spiral portions are stacked, the plurality of layers of spiral portions are electrically connected so that currents in the same direction flow, the electromagnetic ultrasonic probe is characterized in that a fourth insulating film is provided between two adjacent layers of the plurality of layers of spiral portions.

4. The electromagnetic ultrasonic probe according to claim 1 or 2, wherein the spiral portion is provided with a linear portion in which the conductors are arranged linearly, and the electromagnetic ultrasonic probe is characterized thereby.

5. The electromagnetic ultrasonic probe according to claim 4, wherein the spiral portion is formed in an oval shape, and the electromagnetic ultrasonic probe is characterized thereby.

6. The electromagnetic ultrasonic probe according to claim 4, wherein the coil is provided with two spiral portions, the two spiral portions are arranged such that the linear portions are adjacent to each other on a plane, and further, the winding directions of the conductors of each other are opposite to each other, and the electromagnetic ultrasonic probe is characterized thereby.

7. The electromagnetic ultrasonic probe according to claim 1, wherein the insulating thread is formed of glass fiber, and the electromagnetic ultrasonic probe is characterized thereby.

8. The electromagnetic ultrasonic probe according to claim 1, wherein the first insulating film and the second insulating film are formed of a ceramic sheet, and the electromagnetic ultrasonic probe is characterized thereby.

9. The electromagnetic ultrasonic probe according to claim 1, wherein An electromagnetic ultrasonic probe, wherein the magnet is a samarium cobalt magnet.

10. An electromagnetic ultrasonic flaw detector, comprising the electromagnetic ultrasonic probe according to Claim 1.

11. An electromagnetic ultrasonic probe having a magnet that forms a static magnetic field in a test object, a coil that generates eddy currents in the test object, a first insulating film disposed between the test object and the coil, and a second insulating film disposed between the magnet and the coil, wherein the coil includes a conductor having a spiral portion wound in a spiral shape on a predetermined plane, and an insulating thread that is a heat-resistant filamentous insulator, wherein the insulating thread is disposed between two adjacent conductors of the conductor, when the diameter of the conductor is d1, the diameter of the insulating thread is d2, and the distance between the first insulating film and the second insulating film is D, the following formula (1) 【Number 1】 is satisfied. An electromagnetic ultrasonic probe characterized by this.

12. An electromagnetic ultrasonic probe having a magnet that forms a static magnetic field in a test object, a coil that generates eddy currents in the test object, a first insulating film disposed between the test object and the coil, and a second insulating film disposed between the magnet and the coil, wherein the coil includes a conductor spirally wound around the magnet so as to be arranged on a surface of the magnet facing the test object, and an insulating thread that is a heat-resistant filamentous insulator, wherein the insulating thread is disposed between two adjacent conductors of the conductor, An electromagnetic ultrasonic probe, characterized in that the diameter of the insulating thread is larger than a value obtained by subtracting the radius of the conductor from the distance between the first insulating film and the second insulating film.

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