JPH0129568Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to the improvement of an ultrasonic probe for detecting defects on the inner and outer surfaces of steel pipes and the surface layer of round bars.

First, regarding the conventional ultrasonic probe, Figure 1a,
This will be explained using b.

FIG. 1a is a cross-sectional view of a conventional ultrasonic probe and a diagram showing the propagation path of ultrasonic waves. FIG. 1b is a flaw detection waveform diagram using a conventional ultrasonic probe.

In Figures 1a and b, 1 is a vibrator, 2 is a wedge,
3 is a case, 4 is a partition plate, 5 is a water reservoir portion in which the inside of the case 3 is divided by the partition plate 4, 6 is a reflector plate, 7
8 is a longitudinal wave mode ultrasonic wave, 8 is a transverse wave mode ultrasonic wave, 9 is a contact medium such as water or oil, 10 is a test material, 1
1 is a defect, 12 is a transmitted pulse, 13 is a surface echo, 14 is an imaginary echo caused by transverse mode ultrasound,
15 is a defect echo, 16 is a coupling echo from the reflection plate 6, A is the surface of the wedge 2 facing the specimen 10, B is the surface of the wedge 2 that comes into contact with the water reservoir 5, θ ₁ is the specimen 10 This is an angle provided for temperature compensation on the surface of the wedge 2 facing the .

In a conventional ultrasonic probe, ultrasonic waves generated by a transducer 1 reach the surface of a specimen 10 via a wedge 2 and a contact medium 9. On the surface of the test material 10, the ultrasonic waves are broadly branched into three paths. The first path is a reverse path back to the vibrator 1 and appears as a surface echo 13. The second path propagates inside the test material 10 and reaches the defect 11,
It returns to transducer 1 via the reverse path again, which is defective echo 1.
Appears as 5. The third path propagates in the direction of the water reservoir 5, but when the ultrasonic wave is incident on the A side of the wedge 2, the ultrasonic wave propagating through the wedge 2 becomes a longitudinal wave mode ultrasonic wave shown by the solid line in the figure. 7 and is further branched into transverse wave mode ultrasonic waves 8 shown by broken lines in the figure.
These two modes of ultrasonic waves propagate through the wedge 2.
The component that reaches the B side of
It branches into a component reflected to the A-plane side. The ultrasonic wave that has reached the reflection plate 6 returns to the transducer 1 via the reverse path again and appears as a coupling echo 16. By constantly detecting the level and position of this coupling echo 16, it is possible to check whether the ultrasonic probe is operating normally and the acoustic coupling including the positional relationship between the ultrasonic probe and the test material 10. The status will be checked.
In addition, the ultrasonic waves reflected toward the A side of the wedge 2 are
Since it has a structure that becomes smaller as it approaches the tip, each time it is reflected from the A side and the B side, the reflection angle decreases by ₁ at the angle θ set on the A side of the wedge 2, and propagates to the tip of the wedge 2. Finally, the angle of incidence with respect to the A plane approaches 90° and begins to reverse. The sound pressure of this returning ultrasonic wave is between the A side and B side of wedge 2.
The higher the number of reflections between surfaces, the lower the value.

Therefore, in the case of the ultrasonic wave 7 in the longitudinal wave mode, since the angle at which the ultrasonic wave 7 first enters the A side of the wedge 2 from the contact medium 9 is large, there are a considerable number of reflections for the ultrasonic wave to go back, and the sound pressure is It gets lower. However, in the case of the ultrasonic wave 8 in the transverse wave mode, the sound speed of the ultrasonic wave propagating in the wedge 2 is about 1/2 that of a longitudinal wave, so according to Snell's law, the ultrasonic wave returns with a considerably smaller number of reflections. The sound pressure of the reflected wave from the A side of the wedge 2 due to the ultrasonic wave 8 in the transverse wave mode is quite high and appears as an imaginary echo 14, which significantly lowers the S/N ratio in the flaw detection signal.

This invention significantly improves these conventional drawbacks and provides an ultrasonic probe with a good S/N ratio.

An embodiment of this invention will be described below in detail with reference to FIG.

FIG. 2a is a cross-sectional view of the ultrasonic probe according to this invention and a diagram showing the propagation path of ultrasonic waves. FIG. 2b is a flaw detection waveform diagram when using the ultrasonic probe according to this invention.

In Figures 2a and b, 1 is a vibrator, 2 is a wedge, and 3
is a case, 4 is a partition plate, 5 is a water reservoir, 6 is a reflective plate, 7 is an ultrasonic wave in longitudinal wave mode, 8 is an ultrasonic wave in transverse wave mode, 9 is a contact medium, 10 is a test material, 11 is a defect, 12 is a transmission pulse, 13 is a surface echo, 15
is a defect echo, 16 is a coupling echo, A is the surface of the wedge 2 facing the test material 10, B is the surface of the wedge 2 that comes into contact with the water reservoir 5 of this invention and is parallel to the A surface,
θ ₁ is an angle provided on the surface of the wedge 2 facing the test material 10 for temperature compensation.

In the ultrasonic probe according to this invention, since surface A of the wedge 2 facing the specimen 10 and surface B contacting the water reservoir 5 are parallel, the ultrasonic wave 7 in the longitudinal wave mode inside the wedge 2 Even if a transverse wave mode ultrasonic wave 8 is generated, it propagates to the tip of the wedge 2 while reflecting between the A side and B side of the wedge 2 at the same angle at which it first entered the A side of the wedge 2 from the contact medium 9. do. Therefore, ultrasonic waves in transverse wave mode with a small number of reflections, which was a problem with conventional probes8
Therefore, the imaginary echo 14 caused by this phenomenon is not generated, and the S/N ratio is greatly improved.

Also, the dimensions sandwiched between the A side and B side of this wedge 2,
The thinner the so-called wedge 2 is, the more the number of reflections of the ultrasonic waves increases, thereby further improving the effect. Experiments have shown that when the thickness of the wedge 2 is 2 to 3 mm, the level of the coupling echo 16 is high, and the imaginary echo 14 is hardly generated, resulting in good results.

As described above, this invention provides an ultrasonic probe with a good S/N ratio by making the surface of the wedge that faces the specimen and the surface that abuts the water reservoir parallel.

[Brief explanation of the drawing]

Figure 1a is a cross-sectional view of a conventional ultrasonic probe and a diagram showing the ultrasonic propagation path, Figure 1b is a diagram of its flaw detection waveform, and Figure 2a is a cross-section of the ultrasonic probe according to this invention. Fig. 2B is a diagram showing the ultrasonic propagation path, and Fig. 2b is a waveform diagram of the flaw detection. In the figure, 1 is a vibrator, 2 is a wedge, 3 is a case, 4 is a partition plate, 5 is a water reservoir, 6 is a reflector, and 7
is a longitudinal wave mode ultrasonic wave, 8 is a transverse wave mode ultrasonic wave, 9 is a contact medium, 10 is a test material, 11 is a defect,
12 is a transmitted pulse, 13 is a surface echo, 14 is an imaginary echo, 15 is a defect echo, 16 is a coupling echo, and A and B are wedge surfaces. In the drawings, the same or corresponding parts are designated by the same reference numerals.

Claims (1)

[Scope of utility model registration request] In an ultrasonic probe that performs ultrasonic angle flaw detection by providing a gap between the test material and the ultrasonic probe and filling the gap with a liquid contact medium such as water or oil, the transmission and reception of ultrasonic waves is performed. a wedge for fixing the transducer at a predetermined angle to the surface of the material being tested; a case for protecting the transducer and fixing the wedge; and preventing water from entering the transducer. Shikiri board and
A water reservoir surrounded by the wedge, a case, and a partition plate, and a reflective plate provided in the water reservoir, and the ultrasonic beam propagation path between the reflective plate and the surface of the material to be inspected. An ultrasonic probe characterized in that the surface of the wedge that faces the test material and the surface that abuts the water reservoir are parallel.