JPH02184755A - Probe for surface wave - Google Patents

Abstract

PURPOSE:To generate the surface wave efficiently at a correct angle of incidence even if the propagation speed of the surface wave in a body to be inspected is unknown by converging the beam axis of an ultrasonic wave emitted by a vibrator on the center of the circle of the circumferential surface of a wedge. CONSTITUTION:The abutting surface 1b of the probe is made to abut on the surface 6a of the body to be inspected and respective vibrators 2 are switched and applied with a voltage in order by electron scanning, etc., at the same time, so that the beam axes B of ultrasonic waves emitted by the vibrators 2 pass the center C of the circle and are made incident on the body 6 to be inspected. Then many vibrators 2 are arrayed and arranged on the circumferential surface 1a having a 90 deg. center angle closely to each other, so the different angles of incidence of the ultrasonic waves are about 0-90 deg. and the beam axis B of some vibrator 2 is made incident on the body 6 to be inspected at an angle of incidence where a surface wave can be generated, thus generating the surface wave even if the propagation speed of the surface wave in the body 6 to be inspected is unknown.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a surface wave probe that generates surface waves in a subject, and particularly relates to a surface wave probe that generates surface waves in a subject, even when the propagation speed of the surface waves in the subject is unknown. The present invention relates to a probe suitable for generating and receiving surface waves.

[Conventional technology]

Similar to the wedge of an angle probe, in order to generate a surface wave using a wedge made of plastic, etc., the refraction angle must be 90°.
It is necessary to make the ultrasonic wave incident at an angle of incidence that satisfies the law of refraction (Snell's law) so that This angle of incidence is determined using the law of refraction from the propagation speed of the surface waves in the object, so for objects whose surface wave propagation speed is known, it is easy to design a wedge that can generate surface waves. A surface wave probe made specifically for the object made of that material was manufactured.

[Problem to be solved by the invention]

However, when performing flaw detection using surface waves, there are cases where the propagation speed of the surface waves is unknown at the site, and there are cases where the propagation velocity of the surface waves is unknown or unknown, and there are also cases where so-called new materials are being tested.

Nowadays, many new materials are being put into practical use in various places, and the propagation speed of surface waves is often unknown. In this way, for a subject whose surface wave propagation velocity is unknown or unknown, it is not possible to determine the correct angle of incidence that can generate surface waves.
There was a problem in that it was difficult to manufacture a probe that efficiently generated surface waves.

In view of the problems of the prior art described above, the present invention provides a surface wave probe that can efficiently generate surface waves at the correct angle of incidence even when the propagation speed of the surface waves in the object is unknown. The purpose is to

[Means to solve the problem]

In order to achieve the above object, the surface wave probe of the present invention has the following features:
In a surface wave probe in which a transducer is provided on the back side of a wedge, the wedge is provided with a surface that contacts the subject and a circumferential surface on which a number of transducers are attached, and the side shape of the wedge is set to the surface of the subject. A large number of transducers are formed in a fan shape with the center of the circle on the circumferential surface located on the surface that contacts the circumferential surface, and are attached to the circumferential surface so that the beam axis of the ultrasonic waves emitted by each transducer is aligned with the circle. The arrangement is such that they are concentrated at the center of a circle on the circumference.

[Operation] With the above configuration, when voltage is applied to a large number of transducers attached to the circumferential surface of the wedge simultaneously or by sequentially switching each transducer by electronic scanning, the ultrasonic waves ( The beam axes of both longitudinal waves and transverse waves enter the subject through the center of a circle on the circumferential surface. In this case, for example, if the central angle of the sector is 90°, the angle will be 0° to 90°.
It will be incident at an angle of incidence of °. By making the mounting pitch of the transducers close, any one of the transducers can inject the ultrasonic wave at the correct incident angle to generate a surface wave, thereby generating a surface wave in the subject.

〔Example〕

An embodiment will be described with reference to FIGS. 1 and 2. In the figure, reference numeral 1 denotes a sector-shaped wedge with a side surface having a center angle of approximately 90°, and has a circumferential surface 1a and a surface tb that closely contacts the surface 6a of the subject 6. The center C of the circle of the circumferential surface 1a is located on the contact surface 1b, and the contact surface 1b is located on the object surface 6.
Naturally, when it is in close contact with the surface 6a
located above. Reference numeral 2 denotes a large number of transducers arranged in close proximity to each other on the circumferential surface 1a. They are arranged so as to be concentrated at the center C of the circle 1a. As shown in FIG. 1, the area around the center C of the circle is shaped so that the area of the contact surface 1b has a margin so that the ultrasonic waves can efficiently and stably enter the subject 5, that is, the center C of the circle. It is formed in a shape having an abutting surface lb around the periphery. 3 is a damper attached to the back of vibrator 2, 4 is wedge 1
, a vibrator 2, and a damper 3 are installed inside. A cable 5 connects each vibrator 2 to an ultrasonic flaw detector (not shown) or the like.

Now, when the contact surface tb of the probe configured as described above is brought into contact with the object surface 6a, and a voltage is applied to each transducer 2 simultaneously or by sequentially switching each transducer 2 by electronic scanning or the like, The beam axis B of each ultrasonic wave (longitudinal wave or transverse wave) emitted by each transducer 2 is incident on the subject 6 through the center C of the circle. In this embodiment, a large number of transducers 2 are arranged close to each other and aligned on the circumferential surface 1a with a central angle of about 90', so that the different incident angles of the ultrasonic waves range from about 06 to 906. range, the beam axis B of one of the transducers 2 is incident on the object 6 at an incident angle that can generate a surface wave, and even if the propagation speed of the surface wave in the object 6 is unknown, the surface wave is generated. can be generated.

Figure 2 shows an example of how the vibrators 2 are arranged on the circumferential surface 1a of the wedge 1. The pitch between the two rows is shifted by 172 pitches in order to make the rows closer together. By adopting this arrangement, the number of different angles of incidence is doubled compared to the arrangement with only one example, making it possible to efficiently enter the incidence at a more correct angle of incidence, and at the same time allowing for more different kinds of It can correspond to the subject.

In addition, in the case of applying a voltage to each transducer 2 to emit ultrasonic waves by sequentially switching the voltage using the electronic scan, etc., an ultrasonic flaw detector (not shown) connected to the cable 5 may be used. The display section sequentially displays the sound pressure of the surface waves generated in the subject 6, so by detecting the maximum level of the displayed sound pressure, the transducer generating the maximum level and its angle of incidence can be determined. It is also possible to determine the propagation velocity of the surface wave in the object from the known angle of incidence.

The above description has been made regarding the case where a surface wave is generated by the probe according to the present invention. It has a great effect.

By attaching a large number of oscillators to the circumferential surface of a wedge having a circumferential surface, and concentrating the beam axis of the ultrasonic waves emitted by each of the oscillators at the center of the circle on the circumferential surface of the wedge, Even when the propagation speed of surface waves in the object is unknown, surface waves can be efficiently generated at the correct angle of incidence.

[Brief explanation of the drawing]

FIG. 1 is a partial vertical sectional view of a surface wave probe showing one embodiment of the present invention, and FIG. 2 is a diagram showing an example of the arrangement of the transducer of the probe shown in FIG. 1. .

Claims (1)

[Claims] 1. In a surface wave probe in which a transducer is provided on the back side of a wedge, the wedge is provided with a surface that contacts the subject and a circumferential surface on which a number of transducers are attached, and the side shape of the wedge is set to the surface of the subject. A large number of transducers are formed in a fan shape with the center of the circle on the circumferential surface located on the surface that contacts the circumferential surface, and are attached to the circumferential surface so that the beam axis of the ultrasonic waves emitted by each transducer is aligned with the circle. A surface wave probe characterized by being arranged so as to be concentrated at the center of a circle on the circumference.