JPH0875714A - Flaw detection test method and probe - Google Patents

Abstract

PURPOSE: To provide a flaw detection test method and a probe which facilitate the inspecting of a close contact part with other members even when a testing object in contact with the other members closely. CONSTITUTION: A flexible vibrator 12 provided with electrodes 12b and 12c on both sides of a resin film 12a made of polyvinylidene fluoride is supported on a stainless tape 14 to form a probe 10. The probe 10 is inserted into a gap S formed at a close contact part of a support base 1 with respect to a testing object. Then, an ultrasonic wave P is transmitted to the testing object 2 from the vibrator 12 while being received, to perform an ultrasonic flaw detection. A spring 18a for contact is provided on the rear side of a detecting surface F to bring the detecting surface F into contact with a flaw detecting surface of the testing object 2 with the probe left inserted into the gap S. This prevents the lowering of the intensity of the transmitted or received wave as caused by excessive separation of the vibrator from the flaw detecting surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is applicable to ultrasonic flaw detection tests and AE.
The present invention relates to a flaw detection test method such as a flaw detection test by (acoustic emission) and a probe that can be used in these test methods.

[0002]

2. Description of the Related Art Conventionally, as a probe in an ultrasonic flaw detection test or an AE test, a vibrator having an electrode formed on a hard piezoelectric material such as crystal or ceramics is mainly housed in a small box-shaped case. However, in conducting the flaw detection test of the test body, the probe was only brought into close contact with the surface of the test body.

For example, when another supporting member or the like is brought into close contact with the outer surface of a test body such as a pressure vessel, a slant having a wedge is used to inspect a flaw detection portion covered by the supporting member or the like. It was necessary to attach the angle probe to the vicinity of the support member or the like, or to attach it to the inner surface of the container.

However, in the former method of attachment, it is difficult to detect the flaw depending on the direction of the flaw in the flaw detection portion, and it is also difficult to inspect for the thinning of the flaw detection portion. The latter method of attachment is not always easy to implement due to the structure of the test body.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention is directed to a flaw detection test method and a test method capable of easily inspecting a close part of another member even if the test piece is in close contact with the other member. The purpose is to provide a tentacle.

[0006]

In order to achieve the above object, the first characteristic method of the flaw detection test method according to the present invention is:
A flexible vibrator having electrodes provided on both sides of a resin film is inserted into a gap between test pieces to propagate a sound wave between the test piece and the vibrator.

A second characteristic method of the present invention is, in addition to the first characteristic method, the transducer is a transducer for transmitting and receiving ultrasonic waves, and the resin film is made of polyvinylidene fluoride. Especially.

A first characteristic structure of the probe according to the present invention is the structure which can be used in the flaw detection test method described in the first characteristic method, in which electrodes are provided on both surfaces of the resin film. And a tape-shaped support portion into which the vibrator can be inserted in the gap of the test body.

A second characteristic configuration of the present invention is, in addition to the first characteristic configuration, a proximity for making the detection surface of the vibrator close to the flaw detection surface of the test body while being inserted in the gap. There is a means.

[0010]

According to the first characteristic method of the flaw detection test described above, the vibrator is inserted into the gap of the test body. Since the vibrator is a vibrator having electrodes on both sides of the resin film, It can be made quite thin and can be inserted into narrow gaps. Also, because this oscillator is flexible, even if it is made thin to insert it in a narrow gap, it is less likely to be damaged than a conventional oscillator that uses quartz or ceramics, and the gap is bent. Even if the probe is inserted, it can be inserted, and even if the gap is further narrowed by the load acting on the test body, the probe will not be easily damaged. Then, an ultrasonic flaw detection test or an AE test is performed by propagating a sound wave between the test body and the vibrator.

On the other hand, according to the above-mentioned second characteristic method, since the vibrator is a transducer for transmitting and receiving ultrasonic waves, the flaw detection test and the test of the test body facing the gap portion using only this vibrator are performed. It is possible to test the thinning condition of the specimen.

Further, according to the first characteristic configuration of the above-mentioned probe, since the tape-shaped support portion into which the vibrator can be inserted into the gap of the test body is provided, the vibrator is disposed in the gap considerably. It is possible to insert it into the recessed part.

Further, according to the second characteristic construction, since the proximity means is provided for bringing the detection surface of the vibrator close to the flaw detection surface of the test body while being inserted in the gap, the vibrator is provided. It is possible to prevent the intensity of the transmitted wave or the received wave from decreasing due to being too far from the flaw detection surface.

[0014]

As described above, according to the first characteristic method of the flaw detection test method according to the present invention, even if the test body is in close contact with other members, the probe is placed in the narrow gap of the close contact portion. It is possible to securely mount the probe, and it is possible to easily inspect a close part of the other member, and the probe to be used is not easily damaged, so that a more economical flaw detection test method can be provided. In addition, the gap can be formed by bringing other members such as support legs into close contact with the test body, or by stacking two or more plate materials,
It can also be formed by cutting a slit in the test body itself.

On the other hand, according to the first characteristic configuration of the probe according to the present invention, the vibrator can be inserted into a considerably deep part in the gap, and it is difficult to detect flaws in the conventional case. It became possible to test the parts that

Further, according to the second characteristic configuration of the above-mentioned probe, even if the transducer is separated from the flaw detection surface by a hand, the transmitted wave or It has become possible to perform reliable flaw detection by preventing the strength of the received wave from decreasing.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a vertical cross-sectional view of a fuel tank to be tested, in which a cylindrical tank 2 is supported by a concrete support base 1. The tank 2 corresponds to a test body, and a curved gap S is formed by bringing the support base 1 into close contact with the tank 2. The probe 10 used in the present embodiment generally has a vibrator 12, a support portion 14 made of a tape-shaped stainless plate for supporting the vibrator 12, and a surface protecting the vibrator 12. Protective layer 16
And a backing material 17 for ultrasonic cutting.

The vibrator 12 comprises a resin film 12a made of polyvinylidene fluoride (PVDF) and electrodes 12b and 12c provided in layers on the front and back sides of the resin film 12a.
When a voltage is applied between 2b and 12c, it functions to emit and further receive an ultrasonic pulse by the piezoelectric effect of the detection surface F on the surface. That is, in this embodiment, the transducer 12 functions as a transducer that transmits and receives ultrasonic waves. Application of voltage to the electrodes 12b and 12c of the resin film 12a and reception of signals are
It is performed via a pair of cables 13 along the support portion 14. The resin film 12a of the vibrator 12 may have a composition other than polyvinylidene fluoride as long as it has a piezoelectric effect.

The supporting portion 14 has a rectangular through hole 14a at the tip thereof, and the vibrator 12 is housed in the through hole together with the protective layer 16 and the backing material 17 to reduce the overall thickness. However, when the gap S is relatively large, the vibrator 1 is provided without providing the through hole 14a.
Alternatively, 2 or the like may be directly attached to the support portion 14. The protective layer 16 protects the detection surface F of the vibrator 12 that transmits and receives the ultrasonic signal P, and is formed of a thin stainless steel plate having a thickness of about 0.1 mm. However, it may be made of resin. Also, the oscillator 12
The backing material 17 attached to the back surface of the is a thin plate made of brass for preventing emission of ultrasonic waves to the back surface. The ultrasonic band used in this embodiment is, for example, 2 to 10 MH.
z, and the thickness of the backing material is λ / 4 to λ / 2
Since the probe 10 may be formed to a certain extent, the thickness of the tip portion of the probe 10 may be as thin as about 1 mm or less in the whole of the vibrator 12, the protective layer 16 and the backing material 17. The material of the backing material is not limited to brass, and copper or resin can be used.

A spring material 18 is provided on the back surface of the tip of the support portion 14.
The vibrator 12 is fixed to the tip of the support 14 by adhering the edge of the backing material 17 housed in the through hole 14a to the edge of the spring plate 18. Also,
A notch 18b is formed in the central portion of the spring plate 18 and is bent into a V shape in a cross-sectional view to form an abutment spring 18a for pressing the central portion of the backing material 17. That is, when the vibrator 12 is inserted into the gap S, the contact spring 18a contacts the detection surface F of the vibrator 12 so as not to separate from the flaw detection surface of the test body due to its elastic force. The contacting means functions as a contacting means, and the contacting means can be composed of not only a spring but also an elastic body such as rubber. A notch 18d for pulling out the voltage application cable 13 from the through hole 14a is formed on the rear end side of the spring member 18.

Using the probe 10 having the above structure, the tank 2
In order to perform a flaw detection test on the bottom of the probe 10, the probe 10 is inserted into the gap S with the detection surface F of the probe 10 facing the tank 2. At this time, if the gap S is filled with a contact medium such as water, machine oil, paste, or glycerin, the propagation of ultrasonic waves becomes more reliable. The detection surface F of the vibrator 12 is
The elastic force of the abutment spring 18a abuts the flaw detection surface of the tank 2. Further, since the ultrasonic waves transmitted from the vibrator 12 are not propagated to the back surface by the action of the backing material 17, it is possible to prevent the disturbance caused by the ultrasonic waves propagating to the support base 1 side. According to the flaw detection test method according to the present embodiment, even if the fuel is not removed from the tank 2 and then the probe is not mounted therein, rainwater is accumulated between the gaps S of the tank 2 and the bottom of the tank 2 is removed. When it is corroded, the portion can be easily inspected.

Next, a second embodiment of the present invention will be described with reference to FIG. This figure is a perspective view showing an attachment portion of the heat transfer thin tubes 3 to the tube plate 4 in the shell-and-tube heat exchanger. Although not shown, the heat transfer thin tubes 3 are arranged in parallel. . In this embodiment, the vibrator 12 is inserted into the circular gap S formed between the heat transfer thin tube 3 and the tube plate 4 to perform a flaw detection test on the heat transfer thin tube 3. This embodiment is similar to the first embodiment in that the protective layer 16 and the backing material 17 are attached to the front and back of the vibrator 12 provided with electrodes on both sides of the resin film, but the support portion 14 is used. The difference from the first embodiment is that the vibrator 12 is used alone instead. By using the vibrator 12 in this way, it is possible to detect flaws in the narrower gap S. It should be noted that the voltage is applied to the electrodes by applying the protruding portion 12 protruding to one end side of the vibrator 12.
Perform on d.

By directing the detection surface F of the vibrator 12 opposite to the back side on which the backing material 17 is attached to the heat transfer thin tube 3 side, it is possible to perform a flaw detection test on only the heat transfer thin tube 3. In order to inspect the entire circumference of the support portion of the heat transfer thin tube 3 by the tube plate 4, it is sufficient to sequentially rotate the vibrator 12 in the circumferential direction T, but the vibration is performed so as to cover the entire circumference of the heat transfer thin tube 3 almost entirely. The child 12 may be formed longer. Further, by dividing the electrode 12b into a plurality of pieces along the circumferential direction T, the heat transfer thin tube 3 having a relatively large diameter can be inspected. In addition, the flaw detection of the portion of the heat transfer thin tube 3 supported by the tube sheet 4 is performed by the conventional remote control.
According to the Tofield flaw detection method, since it is difficult to determine the test result due to the influence of the tube sheet 4, the present embodiment, which can remove the influence of the tube sheet 4, is highly practical.

Next, a third embodiment of the present invention will be described with reference to FIG. In this embodiment, a gap S is formed by stacking two steel plates 5 and 5, and the vibrator 12 is formed in the gap S in the lateral direction of the paper in a direction perpendicular to the paper. By moving the two steel plates 5 and 5, the entire surface is inspected by scanning once. The vibrator 12 used in the present embodiment is an electrode 12b provided on one surface of a resin film 12a which is elongated in the lateral direction of the paper.
Is divided into several pieces at intervals of about 1 cm,
The other is provided in a continuous manner to form an array device as a whole. Then, by applying a pulse voltage between the electrodes 12b and 12c, ultrasonic waves P are transmitted to and received from both the upper surface and the lower surface of the resin film 12a. In this way, the flaws of the steel plates 5 and 5 are determined by receiving the signals from both sides by one flaw detection, and it shows when either of the two steel plates 5 and 5 has a flaw. The signal is received. In addition,
By stacking a plurality of steel plates 5 and sequentially detecting a plurality of adjacent gaps with the vibrator 12, it is possible to specify the damaged steel plate 5 by pinching and sandwiching.

On the other hand, according to the fourth embodiment shown in FIG. 6 (b), since the vibrators 12 according to the previous embodiment are provided on both sides of the backing material 17, when a scratch signal is received. In addition, it is possible to determine which of the two steel plates 5 and 5 has a scratch.

Next, other embodiments of the present invention will be listed below. In the above-described first embodiment, the contact spring 18a is provided on the rear surface side of the vibrator 12 in order to configure the contact means for contacting the detection surface F of the vibrator with the flaw detection surface. As shown in FIG. 7, by providing a magnet 19 on the peripheral portion of the vibrator 12, 19 can be magnetically attached to a ferromagnetic test body, and the detection surface F of the vibrator 12 is brought into contact with the flaw detection surface. You may.
In this case, as the material of the magnet 19, it is desirable to use a flexible magnet in order to prevent damage due to the narrowing of the gap S.

If both surfaces of the gap S are made of a ferromagnetic material, a protrusion 25a may be provided on the back surface of the vibrator 12 so that the magnet 19 will not be attracted to the surface other than the test body. It is desirable to provide a layer of the non-magnetic material 25 having substantially the same shape as the spring material 18 of the first embodiment.

In the contact means, the first slope 25a is provided on the back side of the vibrator 12 and the second slope 26a is provided at the tip of the vibrator 12 as shown in FIG. The probe tape 26 is inserted from the back side of the vibrator 12 after the probe 10 is inserted, and the second slope 26a is brought into contact with the first slope 25 to detect the detection surface F of the vibrator 12. You may make it comprise the contact means 24 which contact | connects a flaw detection surface. At this time, depending on the size of the gap S, the contact tape 26
By changing the thickness of the, it is possible to test various gaps.

Further, as shown in FIG. 8A, the supporting portion 1
The probe 10 may be configured by forming the entire 4 with a spring material and forming the entire supporting portion 14 in a spiral shape with the detection surface side of the vibrator 12 facing the center side. By thus forming the entire supporting portion 14 in a spiral shape to form a spiral spring, a contact means for contacting the detection surface of the vibrator 12 with the flaw detection surface by the elastic force of the supporting portion 14 is configured. It becomes possible.

In order to perform a flaw detection test using the probe according to the embodiment, as shown in FIG. 8 (b), the gap S formed by the test body 6 and the other member 7 is located further back. The test object may be the one having the enlarged portion 8. That is, the flaw detection test method according to the present invention can be performed not only in the gap S but also in the enlarged portion 8 that has passed through the gap S. In addition, in the case of FIG. 8B, the flaw detection surface of the test body 6 is formed so as to bend downward as it goes deeper, but the flaw detection surface is formed so as to bend upward as it goes deeper. In the latter case, the same effect as that of the present embodiment can be obtained even if the entire supporting portion 14 is formed of a linear spring material. Therefore, the contact means can be configured by forming the entire supporting portion 14 with an elastic body such as a leaf spring.

To form the supporting portion 14, as shown in FIG. 9, a saw-toothed blade 28 may be provided at the tip portion thereof. This is because by providing the blade 28 in this manner, even when a foreign matter is present in the gap S, the blade 28 at the tip thereof can remove the foreign matter.

In the test methods according to the third and fourth embodiments, the contact medium is interposed between the detection surfaces F and F and the flaw detection surfaces of the steel plates 5 and 5. Even if the detection surface F and the flaw detection surface of the steel sheet are not brought into contact with each other, it is possible to propagate the ultrasonic wave and perform the flaw detection test of the steel sheet. Similarly, in forming the contact means, the gap S
When the flaw detection surface or the like is rough, the detection surface may be brought into proximity without contacting the flaw detection surface. That is, in each of the above embodiments, instead of the contact means, a proximity means for bringing the detection surface of the vibrator close to the flaw detection surface of the test body may be used. The proximity means includes contact means.

The spring plate 18 and the abutment spring 1 in the first embodiment constitute the abutment means and the proximity means.
The detection surface F may be brought into contact with or close to the flaw detection surface by repulsing a pair of members by electromagnetic induction at the portion 8a. In this case, the pair of members that repel each other may be configured by forming a coil pattern in a spiral shape on a resin film by etching to form an electromagnet. Alternatively, a small balloon may be provided at the same portion and air may be blown in to bring the detection surface F into contact with or near the flaw detection surface. That is, the contact means or the proximity means can be configured by a device whose thickness can be increased by operation on the back surface side of the detection surface.

In each of the above embodiments, the vibrator 12 is implemented as a transducer for transmitting and receiving ultrasonic waves, but the vibrator 12 may be implemented for transmitting or receiving ultrasonic waves only. . Furthermore, the vibrator 12 can be implemented as an AE sensor for receiving AE waves. Needless to say, each of the above-described embodiments can be carried out independently, or can be carried out in combination with each other.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part of a fuel tank for explaining a flaw detection test method according to a first embodiment.

FIG. 2 is a longitudinal sectional view of a main part of the probe.

FIG. 3 is an AA line bullet surface view of FIG. 2;

FIG. 4 is a plan view of FIG.

FIG. 5 is a view for showing a flaw detection test method according to a second embodiment of the present invention, and is a perspective view of a main part near a tube plate in a shell and tube heat exchanger.

FIG. 6 is a longitudinal sectional view of an essential part for explaining a flaw detection test method using a gap formed by stacking steel plates,
(A) shows a 3rd Example, (b) shows a 4th Example.

FIG. 7 is a view corresponding to FIG. 2 for explaining the fifth embodiment.

FIG. 8 shows a sixth embodiment, (a) is a schematic side view of the probe, and (b) is a schematic cross-sectional view showing a usage state of the probe according to (a).

FIG. 9 is a plan view of an essential part for showing a seventh embodiment.

[Explanation of symbols]

 12a Resin film 12b, 12c Electrode 12 Transducer 2, 3, 5, 6 Test body S Gap P Sound wave.

Claims (4)

[Claims] 1. An electrode (12) is provided on both sides of a resin film (12a).
b, 12c) and a flexible vibrator (12)
It is characterized in that it is inserted into the gap (S) of the test body (2, 3, 5, 6) to propagate a sound wave (P) between the test body (2, 3, 5) and the vibrator (12). The flaw detection test method. 2. The vibrator (12) is a transducer for transmitting and receiving ultrasonic waves, and the resin film (12)
The flaw detection test method according to claim 1, wherein a) is made of polyvinylidene fluoride. 3. A probe (10) that can be used in the flaw detection test method according to claim 1, comprising a resin film (12).
a) A flexible vibrator (12) provided with electrodes (12b, 12c) on both surfaces of (a), and a gap (S) between the vibrator (12) and the test body (2, 3, 5, 6). A probe provided with a tape-shaped support portion (14) that can be inserted into the probe. 4. The detection surface (F) of the vibrator (12) in a state of being inserted into the gap (S), the test body (2, 3, 3).
Proximity means (18) for approaching the flaw detection surface of (5, 6)
a, 19, 24, 14) are provided.