JPH02208557A - Array type skew probe - Google Patents

Abstract

PURPOSE:To enable the checking of an acoustic coupling between a skew probe and a test object by arranging a plurality of rectangular piezo-electric vibrators with the same widths (a) and at least one piezo-electric vibrators with widths less (a). CONSTITUTION:This array type skew probe is provided with rectangular piezo-electric vibrators 11-1n with the same widths (a) determined optimally to detect defects, and additionally, other piezo-electric vibrators 3 with widths (b) which is determined so that an directivity angle equivalent to an angle theta of a wedge 4 gives a sound pressure from a peak to -3 to -6dB or so. The piezo-electric vibrators 3 are driven separately to obtain an ultrasonic wave 8 vertically incident into the surface and the bottom surface of a test object 8. This enables the checking of an acoustic coupling by monitoring a bottom surface echo.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an array type probe for ultrasonic flaw detection for detecting defects existing inside a square steel piece or the like.

[Conventional technology]

FIG. 2(a) is a cross-sectional view of a conventional array type probe.

Figure aE2 (to) is a bottom view of the array type probe showing the shape of the piezoelectric vibrator.

In the figure, (1') is the pressure t [vibrator, (2I is the backing material, a is the width in the arrangement direction of the piezoelectric vibrator (1'), and D is the length of the piezoelectric vibrator (orthogonal to one arrangement direction). be.

Conventional array type probes are configured as described above.
A plurality of tanzaku-shaped piezoelectric vibrators (1') are arranged and have the same width a and b. In addition, an appropriate value is selected for the length D of the piezoelectric vibrator (one length D) based on the flaw detection distance.

When using the above array type probe for linear scanning, multiple piezoelectric vibrators (1') are transmitted and received as a set,
By combining a plurality of the piezoelectric vibrators (1') and transmitting and receiving them while sequentially shifting the same pattern, ultrasonic beams of the same pattern are electronically scanned at high speed to perform a flaw detection test.

[Problem to be solved by the invention]

As mentioned above, piezoelectric transducers with the same width a (array type probes lined up) are the best pattern for detecting defects, especially when used as an angle probe in automatic flaw detection equipment. If the ultrasonic beam was simply scanned, the width of the ultrasonic beam was narrow and the directivity was sharp, making it impossible to check whether the acoustic coupling between the angle probe and the test specimen was sufficient.

In other words, a highly directional ultrasonic beam propagates diagonally through the specimen, and the reflected wave from the bottom surface of the specimen (bottom echo) cannot be obtained. No reflected waves were obtained.

Also, it is not possible to confirm whether the ultrasonic waves are propagating normally from the array type angle probe into the test specimen. Piezoelectric vibrator (1
The smaller the width a of piezoelectric vibrator (1'), the wider the flaw detection range will be unless the number of arrays is increased.
Reducing the width a not only increases the price of the array type probe (it also leads to an increase in the price of the transmitter/receiver), but it also poses an uneconomical problem.

This invention was made to solve the above problems,
A plurality of tanzaku-shaped piezoelectric vibrators (1') with a constant width a,
It is possible to check the acoustic coupling between the angle probe and the test specimen by equipping one or more tanza-shaped piezoelectric vibrators (1') with a smaller width than the tanza-shaped piezoelectric vibrators (1') with a certain width a. The purpose is to do so.

[a! ! Means to solve the problem]

The array type bevel probe according to the present invention has several tanzaku-shaped piezoelectric vibrators having a constant width in the direction in which the tanzaku-shaped piezoelectric vibrators are arranged, and a It is equipped with one or more tanzaku-shaped piezoelectric vibrators having a directivity that allows ultrasonic waves of sufficient intensity to be incident perpendicularly on the surface of the specimen at a given position. [Function] The array type bevel according to the present invention When detecting defects, the probe transmits and receives multiple tandem-shaped piezoelectric vibrators with a certain width at the same time, but when checking acoustic coupling, the probe has a smaller width than the tangy-shaped piezoelectric vibrators with a certain width. By transmitting and receiving with the tanzaku-shaped piezoelectric vibrator alone, a component with sufficient intensity is generated that allows the ultrasonic waves to be incident perpendicularly to the surface of the specimen, even at the angle required for an angle probe. Acoustic coupling can be checked by detecting the bottom 5iJ echo of the test piece.

〔Example〕

FIG. 1 is a sectional view of an array type angle probe showing an embodiment of the present invention.

In the figure, (11) to (1n) are tanzas (
(3) is a narrow tanza (shaped) piezoelectric vibrator with wide directivity according to the present invention; (4) is a wedge for obliquely injecting ultrasonic waves into the test specimen; (5) is the couplant,
(6) is the test piece, (7) is the ultrasonic wave that propagates obliquely in the test piece (6), (81 is generated from the tanzaku-shaped piezoelectric vibrator (3) and is incident perpendicularly from the surface of the test piece (6). Ultrasound.

θ is the angle within the wedge (4) for propagating the ultrasonic wave obliquely in the test specimen (6).

When performing oblique flaw detection with the array type bevel probe configured as above, the width a of the tandem-shaped piezoelectric vibrators (11) to (1n) and the entire The number of piezoelectric vibrators (11) to (1n), the pressure 1M to be simultaneously transmitted and received at one time, and the number of vibrators (11) to (1n) are determined. The ultrasonic wave (7) generated from the tanzaku-shaped piezoelectric vibrator (11) (1n) determined in this manner is transmitted to the test object according to Snell's law, depending on the angle θ provided on the wedge (4). (6) It will propagate diagonally inside. At this time, since the ultrasonic beam has a sharp directivity that is optimally created to detect defects, the bottom echo reflected from the bottom surface of the specimen (6) is usually not obtained. .

However, when processing the flaw detection test results mechanically, such as with automatic flaw detection equipment, it is necessary to check the integrity of the probe and the probe and specimen (
It must be proven that the couplant (5) between the two and 6) was sufficiently filled and the acoustic coupling was sound. Therefore, in the array type bevel probe according to the present invention, in addition to the tanzaku-shaped piezoelectric vibrators (11) to (1n) of a constant width a that are optimally selected for detecting defects, the angle of the wedge (4) is A tanzag-shaped piezoelectric vibrator (3) in which the transducer @b was selected so that the directivity angle at which the sound pressure is within about 13 dB to 15 dB from the peak sound pressure depending on θ corresponds to the angle 0 of the wedge (4). Because it is provided with.

By driving the above-mentioned 11L pressure transducer (3) alone, an ultrasonic wave 181 that is perpendicularly incident on the surface and bottom surface of the test specimen (6) is obtained, and as a result, acoustic coupling is achieved by monitoring the bottom surface echo. Check becomes possible.

〔Effect of the invention〕

As described above, this invention consists of an array type angle probe that makes ultrasonic waves obliquely incident on the surface of a test specimen, and is equipped with several tanzaku-shaped piezoelectric vibrators of a constant width. The width of the tanzaku-shaped piezoelectric vibrator with a constant width is different from the above, and the directivity angle corresponding to the angle provided on the wedge is -3 dB below the peak sound pressure.
By equipping one or more tanza (shaped piezoelectric transducers) with a transducer width that is within about -5 dB from Enables acoustic coupling check.

This has the effect of improving the reliability of flaw detection test results.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an array type bevel tentacle according to the present invention;
FIG. 2 is a sectional view of a conventional array type probe. In the figure, (11) to (1n) and (1') are tanzag-shaped piezoelectric vibrators with a constant width a, (21 is a backing material. (3) is a tanzag-shaped piezoelectric vibrator with wide directivity, and (4) ) is a wedge. (6) is the test piece, (7) is the ultrasonic wave propagating obliquely through the test piece, and 181 is the ultrasonic wave incident perpendicularly from the surface of the test piece. θ is the wedge angle. Note that in the figure The same symbols indicate the same or equivalent parts.

Claims (1)

[Claims] In an array type probe in which tanzaku-shaped piezoelectric vibrators are arranged, there is a wedge with an angle to make the ultrasonic wave obliquely incident on the surface of the test specimen, and a plurality of wedges are provided on the surface with the angle of the wedge. A tanzag-shaped piezoelectric vibrator with a certain width is provided adjacent to the tanzag-shaped piezoelectric vibrator, and the sound pressure is -
An array type bevel probe characterized by comprising a tanzaku-shaped piezoelectric vibrator having a width having a directivity characteristic such that a directivity angle of about 3 dB to -6 dB is equal to the angle provided on the wedge.