JPS6048701B2 - Surface wave method ultrasonic flaw detection probe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a concave lens portion (hereinafter referred to as a concave portion) on the bottom surface of a specimen in surface wave method ultrasonic flaw detection.

), and further relates to a probe that performs flaw detection while supplying water to the space formed by the test material and the recess. In a probe with a conventional shape and mechanism, as shown in Fig. 1, when the ultrasonic waves emitted from the probe pass through the short-range sound wave region, they change in the direction of surface wave propagation within the test material. It propagates while spreading out at a unique angle.

This spread angle is determined by the wavelength of the ultrasonic wave and the projected length dimension of the transducer in a direction perpendicular to the transmission direction.
The spread angle on one side is called the directivity angle θ, which is expressed by the following equation. θ■ (7 days)゜・・・・・・(1) Here, λ: Wavelength, D: Dimension of the transducer In conventional probes, as the emitted surface waves propagate, they spread. As a result, the S/N deteriorates, and errors occur in the evaluation of defects in the material to be inspected due to the influence of the position of the flaw in the material to be inspected.

An object of the present invention is to provide a probe that allows ultrasonic waves emitted from the probe to propagate almost parallel within a material to be inspected, has a good S/N ratio, and can perform flaw detection with high evaluation accuracy. It is in. In addition, the gist of the present invention is that: a concave lens portion provided on a part or the entire surface of the bottom surface of the probe on the side of the sample to be measured; a vibrator provided inside the probe; at least one water supply hole penetrating the concave lens part; water is supplied to the space formed by the concave lens part of the probe and the test material, and water is supplied from the vibrator. This is a surface wave method ultrasonic probe in which ultrasonic waves propagate approximately parallel to the surface wave propagation direction within the test material.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic perspective view illustrating an embodiment of the present invention.

In the figure, 1 is a material to be tested, and 2 is a probe equipped with a vibrator 3 inside. The width of the vibrator 3 is equal to or smaller than the width of the probe 2. Vibrator 3
are arranged with an inclination inside the probe so that the vibrations propagate toward the bottom surface of the sample to be inspected. Further, the probe 2 has a recess 4 on the bottom surface on the side of the test material. This recess 4 has a circular arc shape, and a design example thereof is shown in the seventh example.
As shown in the figure. If the radius of this circular arc is r, it is calculated by the following equation. r=(1-C2/C1)b...
・(2) Here, C: Speed of sound on the incident side (m/Sec)C.

: Speed of sound in the material being tested (m/Sec) b: Focusing position (
TWL) In the embodiment shown in FIG. 7, epoxy resin is used for the probe member, and the material to be tested is steel.

Then, the focal length is set to 700wrm. Therefore, in equation (2), C1=2700m/SeCNc2
=Re2980rT1/SecNb=70077z771
As a proxy, r = -66 threshold can be obtained. Thus, it can be seen that in this example, it is sufficient to provide a concave portion with a radius of 66 m77Z on the bottom surface of the probe. When the width of the probe is 40Tr$L, the height of the recess is approximately 3.5wL, and 50Trrm
In the case of , it becomes approximately 5.577!771. In addition, if the width of the transducer is smaller than the width of the probe, it may be possible to provide a recess on the bottom of the probe corresponding to the entire width of the probe. A concave portion may be provided over a corresponding length, and both ends of the probe may be formed flat. 3 FIGS. 3 to 6 are diagrams showing embodiments of the probe of the present invention.

FIG. 3 shows an embodiment in which the water supply hole 5 is disposed so as to pass through the recess from the top surface of the probe 2 and behind the vibrator 3.

The ultrasonic waves emitted from the vibrator 3 propagate as indicated by an arrow 6. FIG. 4 shows an embodiment in which a leg portion 7 is provided on the bottom surface of the probe 2, and a water supply hole 5' is provided penetrating from the outer peripheral surface of the leg portion toward the recess.

Note that the water supply hole 5' may be provided only on one side of the leg portion 7. In FIG. 5, a recess 4 is provided only in the front 1 of the probe 2, and the remaining 1. This is an example in which the bottom surface of the portion is made flat. Generally, if the recess is provided over the entire bottom surface, air bubbles will not remain in the recess and air purging will be easier. FIG. 6 shows an embodiment in which a water supply hole 5'' passes through the top surface of the probe 2 into the recess 4 and is provided in front of the vibrator 3'.

In this case, the ultrasonic waves are scattered by the water supply hole 5'',
In order to prevent the dead zone from widening, the vibrator 3' is divided into two people and arranged. Now, according to the probe of the present invention, as described above, the S/N ratio is good.

In experiments conducted by the present inventors, an improvement of at least 4 to 2 times was observed in the operating frequency band of 1 to 2 MHz compared to conventional probes.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view illustrating the propagation situation of surface waves by a conventional probe, Fig. 2 is a schematic perspective view illustrating the propagation situation of surface waves by the embodiment probe of the present invention, and Fig. 3 6 to 6 are schematic diagrams illustrating embodiments of the present invention, and FIG. 7 is a schematic diagram illustrating a design example of a probe concave lens portion of the present invention. 1...Test material, 2...Probe, 3,
3'... Vibrator, 4... Concave lens portion (concave portion), 5, 5', 5''... Water supply hole, 6
・・・・・・Ultrasonic propagation direction, 7 ・・・・・・Legs,
D...Width of the vibrator, θ...Directivity angle.

Claims (1)

[Scope of Claims] 1. A concave lens portion provided on a part or the entire surface of the bottom surface of the probe on the side of the specimen; a vibrator provided inside the probe; at least one water supply hole penetrating the lens portion; water is supplied to the space formed by the concave lens portion of the probe and the test material;
A surface wave method ultrasonic flaw detection probe characterized in that the ultrasonic waves from the vibrator propagate substantially parallel to the surface wave propagation direction within the test material.