JPH056533Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a probe for a scanning type flaw detector, and particularly to a probe for a scanning type flaw detector suitable for detecting defects near the surface of a material.

[Conventional technology]

Conventional examples are shown in FIGS. 5 to 8. This eighth
In the figure, reference numeral 1 indicates a scanning type ultrasonic flaw detector, and reference numeral 2 indicates an array type probe. This probe 2 has a plurality of strip-shaped transducers x ₁ , x ₂ , x ₃ ..., x _o arranged in an array as shown in the figure,
These oscillators x ₁ , x ₂ , ..., x _o are fixed to the back plate ₃ as shown in _FIG .
A matching layer 4 and a front plate 5 are respectively installed on the front surface of x _o , that is, on the ultrasonic wave sending side, so that appropriate matching is achieved and ultrasonic waves of a predetermined frequency are transmitted to x _{1 , x 2} , x 2 , x ₂ , etc. ..., x _o are repeatedly sent out to the side of the member to be measured P.
Here, numeral 6 indicates a probe case, numeral 7 indicates a connector section, and numeral 8 indicates a connection cable.

[Problem that the invention attempts to solve]

However, in such conventional examples, the seventh
As shown in the CRT display example in the figure, reflected waves from defects near the surface of the member to be measured P (see _S1 in Figure 5) are transmitted by each vibrator x ₁ , x ₂ , ..., x _o . Since it is recorded and displayed close to the pulse, the defective echo R ₁ is in contact with the transmitted pulse IP,
In some cases, the problem often arises that it is difficult to distinguish the transmitted pulse IP.

Furthermore, in the above conventional example, each vibrator x ₁ ,
x ₂ , the defect S ₂ located at a position slightly shifted from directly below
(See Figure 6), since the transmitted wave has a certain angular spread, a reflected echo R ₂ from a part of it is detected, and therefore,
This has resulted in the inconvenience of displaying the presence of a small defect deep beneath the probe 2.

[Purpose of invention]

The purpose of the present invention is to improve the disadvantages of the conventional example and to provide a probe for a scanning type flaw detector that improves the resolution of the entire array type probe, especially for defects near the surface. do.

[Means for solving problems]

Therefore, in the present invention, a plurality of strip-shaped transducers are arranged on the same flat surface, and the first and second transducers are commonly provided on the ultrasound sending side of each strip-shaped transducer. Equipped with two layers of acoustic delay members,
The entire boundary surface between the first and second acoustic delay members is formed into an arc shape in which a cross section along the longitudinal direction of each strip-shaped vibrator has a convex surface toward each strip-shaped vibrator. As the material of the second acoustic delay member, a material is used in which the sound velocity of the first acoustic delay member is higher than the sound velocity of the second acoustic delay member, and for the first and second acoustic delay members, The structure uses composite materials whose acoustic impedances are close to each other. This aims to achieve the above-mentioned purpose.

[Example of idea]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. Here, the same reference numerals are used for the same constituent members as in the conventional example described above.

First, in FIGS. 1 and 2, reference numeral 10
shows a probe for an array-type scanning flaw detector. Similar to the conventional example described above, this probe 10 includes a back plate 3 and a plurality of strip-shaped vibrators arranged on the same plane at predetermined intervals as shown in FIG.
It has x ₁ , x ₂ , ..., x _o . On the front surface of the rectangular transducers x ₁ , x ₂ , ..., x _o , that is, on the ultrasonic wave sending side, there is an acoustic delay means 20 that acts commonly on each of the transducers x ₁ , x ₂ , ..., x _o . is installed. In this embodiment, the acoustic delay means 20 is formed by stacking the first and second delay members 21 and 22, and the boundary surface of the delay members includes:
A common acoustic lens section 23 is set for each strip-shaped vibrator.

Specifically, as shown in FIG. 2, the acoustic lens section 23 includes a first delay member 21 having a concave abutment surface facing the outside, and a convex abutment that abuts the concave abutment surface almost uniformly. and a second delay member 22 with a contact surface. Here, the first delay member 21 with the concave contact surface is made of a composite material with a sound velocity V ₁ of 3200 m/s and an acoustic impedance Z ₁ of 7.5×10 ⁵ (g/cm ² S). ing. The second delay member with a convex contact surface is made of a composite material with a sound velocity V ₂ of 2400 m/s and an acoustic impedance Z ₂ of 7.0×10 ⁵ (g/cm ² S). . Therefore, since the acoustic impedances Z ₁ and Z ₂ of the first and second delay members 21 and 22 are close to each other, the reflection at the contact surface between the concave and convex surfaces, that is, the acoustic lens portion 23 is so small that it can be ignored.

Next, an example of the action of the acoustic lens section 23 will be explained based on FIG. 4. First, in FIG. 4, the convergence condition is "γ>β". Here, according to the law of refraction, the refraction angle β of the transmitted ultrasonic wave Y is β=sin− ¹ [(V ₂ /V ₁ )・sinα], so if “α=30°” now, “β≒
22° (However, for convenience of explanation, the radius of curvature r was set to 45 mm in FIG. 4). Therefore, since "γ = 25°" in the same figure,
It can be seen that the above-mentioned convergence condition "γ>β" is fully satisfied.

The radius of curvature r of the actually prototyped probe is also
are formed in substantially the same way, and similar lens effects have been obtained in the experimental results.

FIG. 3 shows an example of a screen displayed on the CRT when the scanning type flaw detector probe 10 is operated in the state shown in FIG.

As shown in FIG. 3, according to this embodiment, the acoustic delay means 20 described above acts and the position of the oscillation pulse is temporally largely separated from the surface of the member to be measured. The result is that the reflected waves from the defect _S1 near the surface of the member P are clearly separated and displayed without being affected by the intensity of the oscillation pulse, and at the same time, the acoustic lens section 23 described above functions. Then, the second
As shown in the figure, the defect _S2 , which is not located directly below any of the vibrators x ₁ , x ₂ , ..., x _o , is not detected at all even under the same measurement conditions as in Fig. 6. As shown in FIG. 3, the result was that nothing was displayed on the CRT.

[Effect of idea]

As described above, according to the present invention, a plurality of strip-shaped vibrators are arranged on the same surface and a common acoustic lens part is provided for each vibrator that functions along the longitudinal direction of each vibrator. Even defects close to the surface of the part to be measured can be clearly detected and displayed on the screen, and since composite materials are used as the first and second acoustic delay members, materials with similar acoustic impedance can be used. It is easy to form and use, and therefore it is possible to incorporate an inexpensive and high-performance acoustic lens section, and as mentioned above, the same conditions can be applied to the entire part to be measured, which has a flat measurement surface. It is possible to provide a probe for a scanning flaw detector that is unprecedented and practical and can perform rapid and clear flaw detection of internal defects under the above conditions.

[Brief explanation of the drawing]

Figure 1 is a partially sectional front view showing an embodiment of the present invention, Figure 2 is a partially sectional right side view of Figure 1, and Figure 3 is a screen display of the measurement results in Figure 1. An explanatory diagram showing an example, FIG. 4 is an explanatory diagram of the function of the acoustic lens section, FIG. 5 is a partially sectional front view showing a conventional example, and FIG. 6 is a partially sectional right side view of FIG. 5. FIG. 7 is an explanatory diagram showing an example of the case where the measurement results of FIG. 5 are displayed on a screen, and FIG. 8 is an explanatory diagram showing the overall usage state including FIG. 5. 20...Acoustic delay means, 21...First acoustic delay member, 22...Second acoustic delay member, 23...
Acoustic lens section, x ₁ , x ₂ , x ₃ , ... x _o ... strip-shaped vibrator.

Claims (1)

[Scope of Claim for Utility Model Registration] A plurality of strip-shaped transducers are arranged on the same flat surface, and on the ultrasonic transmission side of each of the strip-shaped transducers, a first The second acoustic delay member is provided in two layers, and the cross section of the entire boundary surface of the first and second acoustic delay members along the longitudinal direction of each of the strip-shaped vibrators is The first and second acoustic delay members are formed in an arcuate shape with a convex surface toward the direction, and the first and second acoustic delay members are made of a material in which the sound velocity of the first acoustic delay member is higher than the sound velocity of the second acoustic delay member. A probe for a scanning flaw detector, characterized in that the first and second acoustic delay members are made of composite materials whose acoustic impedances are close to each other.