JP2011232133A - Inspection method by using guide wave using coagulation of liquid layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the noise level of reflection wave even when an object to be inspected is shaped so that it cannot be excellently brought into contact with a guide wave oscillator.SOLUTION: A liquid holding body for filling liquid between itself and an object to be inspected is prepared and arranged such that space for filling liquid is formed between the liquid holding body and the object to be inspected. The space for filling liquid is filled with liquid. The filled liquid is coagulated. In this state, the guide wave oscillator attached to the liquid holding body is operated to generate guide wave in the object to be inspected and to detect reflection wave of the guide wave passing through the object to be inspected, inspecting the object to be inspected based on the reflection wave.

Description

  The present invention relates to an inspection method using a guided wave utilizing solidification of a liquid layer. More specifically, the present invention relates to an inspection method for generating a guide wave, which is a sound wave propagating in the object to be measured, detecting a reflected wave of the guide wave, and inspecting the object to be inspected based on the reflected wave. About. The frequency of the guide wave is, for example, 1 kHz to several hundred kHz (in one example, 32 kHz, 64 kHz, 128 kHz, etc.).

  The guide wave is generated by a guide wave oscillator attached to the object to be inspected. The guide wave oscillator vibrates the object to be inspected, and thereby generates a guide wave that is a kind of sound wave. The generated / oscillated guide wave propagates along the longitudinal direction in the inspection object.

  The soundness of the object to be inspected is inspected by detecting the reflected wave of the guide wave. The guide wave is reflected as a reflected wave due to a discontinuous portion in the object to be inspected or a change in the cross-sectional area of the object to be inspected. By detecting this reflected wave, the soundness of the object to be inspected is inspected. As the soundness of the object to be inspected, for example, the presence or absence of a defective part such as a scratch or corrosion of the object to be inspected is inspected.

  Examples of the guide wave include an L mode (Longitudinal mode) guide wave and a T mode (Torsional mode) guide wave. The L-mode guide wave propagates in the inspection object while vibrating in the propagation direction, and the T-mode guide wave propagates in the inspection object while vibrating so as to twist the inspection object.

  Such a guide wave is less attenuated than a sound wave used in general sound wave inspection, and the soundness of the object can be inspected over a wide range of the object. A sound wave used in a general sound wave inspection is easily attenuated because, for example, the frequency is as high as 5 MHz and the wavelength is as small as 0.6 mm. On the other hand, since the guide wave as described above has a small frequency of 32 kHz and a large wavelength of 100 mm, for example, it is difficult to attenuate.

  As a prior art document of the present application, for example, there is Patent Document 1 below.

JP 2009-36516 A

However, in the past, since the outer surface of the object to be inspected is uneven, the contact between the guide wave oscillator and the object to be inspected may be incomplete when the guide wave oscillator is attached to the object to be inspected. is there. Here, the incomplete contact means that the guide wave oscillator and the object to be inspected make contact (for example, point contact) only at a plurality of discrete locations.
Due to such incomplete contact, the level of reflected wave noise becomes high, and the object to be inspected cannot be inspected accurately.

  Accordingly, an object of the present invention is to provide an inspection method capable of suppressing the level of reflected wave noise even when the object to be inspected has a shape that cannot be satisfactorily brought into contact with the guide wave oscillator. It is in.

In order to achieve the above-described object, according to the present invention, a guide wave is generated so as to propagate in an object to be inspected, a reflected wave of the guide wave is detected, and the object to be inspected is based on the reflected wave. An inspection method for inspecting,
(A) A liquid holding body for filling a liquid between the object to be inspected is prepared,
(B) The liquid holding body is arranged so as to form a liquid filling space between the liquid holding body and the test object,
(C) filling the liquid filling space with liquid,
(D) solidify the filled liquid;
(E) In this state, by operating a guide wave oscillator attached to the liquid holding body, a guide wave is generated in the object to be inspected,
(F) Utilizing solidification of the liquid layer, characterized in that the reflected wave of the guide wave generated in (E) and propagated through the object to be inspected is detected, and the object to be inspected is inspected based on the reflected wave. An inspection method using a guided wave is provided.

  According to a preferred embodiment of the present invention, in (B), the liquid holding body is disposed so as to surround the test object with the inner peripheral surface of the liquid holding body, so that the space between the inner peripheral surface and the test object is set. A liquid filling space is formed in the substrate.

  Preferably, the liquid filling space is filled with a liquid in a state where at least one of the liquid holding body and the object to be inspected arranged in (B) is cooled below the freezing point of the liquid, so that the (C) and the above (D) is performed simultaneously.

  In (B), when the liquid filling space is filled with the liquid in (C), a sealing material that prevents the liquid from leaking from the liquid filling space is closed between the liquid holding body and the object to be inspected. Provide as follows.

  According to the present invention described above, the liquid is filled between the liquid holder and the object to be inspected, and the filled liquid is solidified. Therefore, the liquid holder and the object to be inspected are not affected by the shape of the object to be inspected. Can be filled with solid. Thereby, the vibration of the object to be inspected can be stabilized (for example, the mode conversion of the guide wave can be prevented), and as a result, the noise level of the reflected wave can be reduced.

The structure for enforcing the inspection method by the guide wave using coagulation | solidification of a liquid layer by embodiment of this invention is shown. It is a flowchart which shows the inspection method by the guide wave using solidification of the liquid layer by embodiment of this invention. (A) shows the amplitude of the reflected wave detected by the inspection method according to the embodiment of the present invention, and (B) shows a comparative example. 4 shows another configuration for carrying out an inspection method using a guided wave using solidification of a liquid layer according to an embodiment of the present invention. 4 shows another configuration for carrying out an inspection method using a guided wave using solidification of a liquid layer according to an embodiment of the present invention. 4 shows another configuration for carrying out an inspection method using a guided wave using solidification of a liquid layer according to an embodiment of the present invention.

  FIG. 1 is a configuration diagram of a guide wave sensor 10 for inspecting a device under test 1 using a guide wave according to an embodiment of the present invention. In FIG. 1, the guide wave sensor 10 is attached to a device under test 1 (wire in this example) made of a ferromagnetic material. 1A is a cross-sectional view taken along the line 1A-1A in FIG. 1B, and FIG. 1B is a cross-sectional view taken along the line 1B-1B in FIG. ) Is a cross-sectional view taken along the line 1C-1C in FIG. 1A, and FIG. 1D is a cross-sectional view taken along the line 1D-1D in FIG.

  The outer surface 1c of the device under test 1 has an uneven shape. In the example of FIG. 1, the device under test 1 is a wire. The wire 1 includes a central strand 1a and a plurality of circulating strands 1b. The circumferential strand 1b extends in the longitudinal direction of the wire 1 while surrounding the central strand 1a so as to be knitted.

  The guide wave sensor 10 includes a liquid holder 3, a seal material 5, a guide wave oscillator 7, and a detection device 9.

  The liquid holding body 3 is for forming a liquid filling space 11 for filling a liquid with the object to be inspected 1. In this embodiment, the liquid holding body 3 is formed of a material that does not allow liquid to pass (for example, rubber or resin). In FIG. 1, the liquid holder 3 has an inner peripheral surface 3 a that surrounds the outer peripheral surface 1 c of the object 1 and forms a liquid filling space 11 between the outer peripheral surface 1 c and the liquid holder 3. In this example, the liquid holding body 3 is formed in a cylindrical shape. The liquid holding body 3 forms a liquid filling space 11 by passing the device under test 1 therethrough.

  The sealing material 5 closes the space between the liquid holding body 3 and the inspection object 1 so that the liquid does not leak from the liquid filling space 11 formed between the liquid holding body 3 and the inspection object 1. is there. In the example of FIG. 1, the sealing material 5 is provided in the gap between the inner peripheral surface 3 a of the liquid holder 3 and the outer surface 1 c of the object 1 to be inspected at the end (axial end) of the liquid holder 3. . In the example of FIG. 1, the sealing material 5 is an adhesive that adheres the liquid holding body 3 and the object 1 to be inspected, but may be another one (for example, an adhesive tape or the like).

  In this embodiment, the guide wave oscillator 7 includes a coil 7a, a permanent magnet 7b, and an AC power source 7c. The coil 7 a is incorporated in the cylindrical liquid holder 3 and extends so as to be wound around the axis of the liquid holder 3. The permanent magnet 7b is attached to the liquid holding body 3 such that one side in the axial direction of the coil 7a (cylindrical liquid holding body 3) is an S pole and the other side in the axial direction of the coil 7a is an N pole. The AC power source 7c applies an AC voltage to the coil 7a.

  The detection device 9 is connected to the coil 7a so that the voltage across the coil 7a can be measured.

  FIG. 2 is a flowchart illustrating an inspection method using a guided wave using solidification of a liquid layer according to an embodiment of the present invention. In this inspection method, a guide wave is generated so as to propagate in the inspection object 1, a reflected wave of the guide wave is detected, and the inspection object 1 is inspected based on the reflection wave.

  In step S <b> 1, the liquid holding body 3 described above is prepared in order to fill the liquid with the object to be inspected 1.

In step S <b> 2, the liquid holding body 3 is arranged so as to form a liquid filling space 11 between the liquid holding body 3 and the test object 1. In the present embodiment, the outer peripheral surface 1c of the test subject 1 is surrounded by the inner peripheral surface 3a of the liquid holding member 3 through the test subject 1 from the end of the test subject 1 (wire) into the liquid holding member 3. The liquid holding body 3 is arranged as described above. Thereby, the space 11 for liquid filling is formed between the inner peripheral surface 3a and the outer peripheral surface 1c.
In step S2, the sealing material 5 that prevents the liquid from leaking from the liquid filling space 11 when the liquid filling space 11 is filled in step S3, which will be described later, is provided with the liquid holder 3 and the device under test. It is provided so as to close the space between 1 In the example of FIG. 1, the seal material 5 is provided in the gap between the inner peripheral surface 3 a of the liquid holder 3 and the outer peripheral surface 1 c of the object 1 to be tested at the axial end of the liquid holder 3.
At this time, it is preferable to seal the liquid filling space 11 while leaving the liquid supply gap 13 by providing the sealing material 5 as described above at both axial ends of the liquid holding body 3. The liquid supply gap 13 is, for example, a hole secured so as to penetrate the sealing material 5.

  In step S3, the liquid filling space 11 is filled with liquid. For example, a tube for supplying a liquid is connected to the liquid supply gap 13, and the pressurized liquid is supplied to the liquid filling space 11 through the tube and the liquid supply gap 13. When this supply is completed, the liquid supply gap 13 may be closed by an appropriate means. The liquid is preferably water, but may be other (eg, an organic solvent).

In step S4, the liquid filled in the liquid filling space 11 is solidified. This coagulation may be performed by bringing liquid nitrogen or dry ice into contact with the device under test 1 or the liquid holder 3. In this step S4, preferably, the liquid in the liquid filling space 11 is completely solidified. However, in step S4, the liquid in the liquid filling space 11 may be partially solidified, and even in this case, the noise of the reflected wave can be sufficiently reduced.
For example, when the liquid is water, the liquid filled in the liquid filling space 11 is solidified using liquid nitrogen or dry ice as described above. When the liquid is other than water, the liquid filled in the liquid filling space 11 is solidified as described above by using a liquid (liquid nitrogen, dry ice or the like) lower than the freezing point of the liquid.

  In step S5, a guide wave is generated in the device under test 1 by operating the guide wave oscillator 7 attached to the liquid holding body 3 while the liquid in the liquid filling space 11 is solidified. In the present embodiment, the AC power supply 7c applies an AC voltage to the coil 7a, thereby operating the guide wave oscillator 7 to generate an L-mode guide wave in the device under test 1.

  In step S6, the reflected wave of the guide wave generated in step S5 and propagated through the object 1 is detected, and the object 1 is inspected based on the reflected wave. In this embodiment, the detection device 9 detects the reflected wave as a voltage across the coil 7a.

FIG. 3A shows a reflected wave detected by performing the above-described inspection method on the wire 1 known to have no defect.
FIG. 3B shows a reflected wave detected for the same wire 1 by omitting steps S3 and S4 in the inspection method described above.
3A and 3B, the horizontal axis indicates the distance (m) from the origin of each position along the longitudinal direction of the device under test 1, and the origin is the position of the guide wave oscillator 7. 3A and 3B, the vertical axis indicates the voltage (V) corresponding to the amplitude of the reflected wave. As can be seen from FIG. 3, in the case of FIG. 3B, a reflected wave (noise) having a large amplitude was detected at a position where no defect exists (position 3 m from the origin), whereas FIG. ), The reflected wave (noise) disappeared.
The following can be seen from FIG. That is, since the liquid is filled between the outer surface 1c of the inspection object 1 and the liquid holding body 3 and the filled liquid is solidified, the liquid holding body 3 and the inspection object regardless of the shape of the inspection object 1. 1 can be filled with a solid. Thereby, the vibration (guide wave mode) of the device under test 1 can be stabilized, and as a result, the noise level can be reduced.

  The present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention. For example, the following modifications 1 to 6 may be arbitrarily combined or employed alone.

[Modification 1]
After step S2, in a state in which at least one of the liquid holding body 3 and the inspection object 1 is cooled to the liquid freezing point or lower (for example, the liquid holding body 3 or the inspection object 1 is brought into contact with liquid nitrogen or dry ice. In this state, the steps S3 and S4 may be performed simultaneously by filling the liquid filling space 13 with a liquid.
In this case, the liquid is solidified almost simultaneously with being supplied to the liquid filling space 13. Therefore, even if the sealing material 5 is not provided, the liquid does not leak from the liquid filling space 13. Therefore, the sealing material 5 may be omitted.

[Modification 2]
The guide wave sensor 10 that generates the L-mode guide wave has been described above with reference to FIG. 1. However, the present invention can also be applied to the guide wave sensor 10 that generates the T-mode guide wave shown in FIG. 4. it can. 4A is a cross-sectional view taken along the line 4A-4A in FIG. 4B, and FIG. 4B is a cross-sectional view taken along the line 4B-4B in FIG. 4A. ) Is a cross-sectional view taken along the 4C-4C arrow in FIG. 4A, and FIG. 4D is a cross-sectional view taken along the 4D-4D arrow in FIG. 4A.
In FIG. 4, a ferromagnetic metal plate 15 made of a ferromagnetic material is wound around the outer peripheral surface of a cylindrical liquid holder 3. A coil 7 a is wound around the outer peripheral surface of the ferromagnetic metal plate 15. Further, the magnet 7b described above is omitted.
Other points of the guide wave sensor 10 in FIG. 4 are the same as described above. When the guide wave sensor 10 of FIG. 4 is employed, the inspection method using the guide wave utilizing the solidification of the liquid layer of the present invention is the same as described above.

[Modification 3]
In the above description, the guide wave sensor 10 that generates the L-mode guide wave has been described with reference to FIG. 1, but the present invention can also be applied to the guide wave sensor 10 that generates the T-mode guide wave shown in FIG. 5. it can. 5A is a cross-sectional view taken along the arrow 5A-5A in FIG. 5B, FIG. 5B is a cross-sectional view taken along the 5B-5B arrow in FIG. 5A, and FIG. ) Is a sectional view taken along the line 5C-5C in FIG. 5A, and FIG. 5D is a sectional view taken along the line 5D-5D in FIG.
In FIG. 5, a cylindrical liquid holder 3 is formed of a ferromagnetic material. A coil 7 a is wound around the outer peripheral surface of the liquid holder 3. Further, the magnet 7b described above is omitted.
Other points of the guide wave sensor 10 in FIG. 5 are the same as described above. Further, when the guide wave sensor 10 of FIG. 5 is employed, the inspection method using the guide wave utilizing the solidification of the liquid layer of the present invention is the same as described above.

[Modification 4]
In the above description, the liquid holding body 3 surrounds the outer peripheral surface 1c of the test object 1 as shown in FIG. In this case, the guide wave oscillator 7 attached to the liquid holding body 3 oscillates at the frequency of the guide wave when it is operated, whereby the liquid is solidified in the liquid filling space 11 via the solidified body. The vibration is transmitted to the inspection object 1 to generate a guide wave in the inspection object 1.
An example of such a guide wave oscillator 7 is shown in FIG. 6A is a cross-sectional view taken along arrow 6A-6A in FIG. 6B, and FIG. 6B is a cross-sectional view taken along arrow 6B-6B in FIG. 6A. ) Is a cross-sectional view taken along arrow 6C-6C in FIG. 6A, and FIG. 6D is a cross-sectional view taken along arrow 6D-6D in FIG. 6A.
In the example of FIG. 6, the guide wave oscillator 7 includes a vibrating body 7d formed of a ferromagnetic material, a coil 7a wound around the vibrating body, and a storage body 7e in which the vibrating body 7d and the coil 7b are incorporated. , And a permanent magnet 7b attached to the housing 7e and an AC power source 7c for applying an AC voltage to the coil 7a. In the permanent magnet 7b, the south pole is located on one axial side of the coil 7a, and the north pole is located on the other axial side of the coil 7a.
It comprises an AC power supply 7c for applying an AC voltage to the coil 7a. Such a guide wave oscillator 7 (the storage body 7 in FIG. 6) is attached to the liquid holding body 3.
The other points of the guide wave sensor 10 in FIG. 6 are the same as described above. When the guide wave sensor 10 of FIG. 6 is employed, the inspection method using the guide wave utilizing the solidification of the liquid layer of the present invention is the same as described above. Even when the guide wave sensor 10 of FIG. 6 is used, an L-mode guide wave is generated in the device under test 1 in step S5.

(Modification 5)
The magnet 7b is a permanent magnet, but may be an electromagnet. In this case, the magnet 7b includes a solid portion (preferably, a core portion formed of a magnetic material) and a coil wound around the solid portion. Moreover, a magnetic field is generated by passing a direct current through the coil. In this case, the other points are the same as described above.

(Deformability 6)
In the above description, the inspected object 1 is a wire, but the present invention can be applied to other inspected objects 1 having an uneven outer surface. For example, a reinforcing bar having an uneven outer surface may be used. The overall shape of the device under test 1 may be tubular or rod-shaped, or may be other shapes.

DESCRIPTION OF SYMBOLS 1 Test object, 3 Liquid holding body, 5 Seal material, 7 Guide wave oscillator, 7a Coil, 7b Permanent magnet, 7c AC power supply, 9 Detection apparatus, 10 Guide wave sensor, 11 Liquid filling space, 13 Liquid supply gap

Claims (4)

An inspection method for generating a guide wave so as to propagate in an object to be inspected, detecting a reflected wave of the guide wave, and inspecting the object to be inspected based on the reflected wave,
(A) A liquid holding body for filling a liquid between the object to be inspected is prepared,
(B) The liquid holding body is arranged so as to form a liquid filling space between the liquid holding body and the test object,
(C) filling the liquid filling space with liquid,
(D) solidify the filled liquid;
(E) In this state, by operating a guide wave oscillator attached to the liquid holding body, a guide wave is generated in the object to be inspected,
(F) Utilizing solidification of the liquid layer, characterized in that the reflected wave of the guide wave generated in (E) and propagated through the object to be inspected is detected, and the object to be inspected is inspected based on the reflected wave. Inspection method using a guided wave.   In (B), by arranging the liquid holder so as to surround the object to be inspected by the inner peripheral surface of the liquid holder, a liquid filling space is formed between the inner peripheral surface and the object to be inspected. The inspection method by the guide wave using the coagulation | solidification of the liquid layer of Claim 1 characterized by the above-mentioned.   (C) and (D) by filling the liquid filling space with liquid in a state where at least one of the liquid holding body and the object to be inspected arranged in (B) is cooled below the freezing point of the liquid. 3. The inspection method using a guide wave using solidification of a liquid layer according to claim 1 or 2, wherein the steps are performed simultaneously.   In (B), the sealing material that prevents liquid from leaking from the liquid filling space when filling the liquid filling space in (C) is closed between the liquid holding body and the object to be inspected. The inspection method by the guide wave using solidification of the liquid layer as described in any one of Claims 1-3 characterized by the above-mentioned.