JPH0521502B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to an ultrasonic probe that performs an ultrasonic flaw detection test to detect defects occurring in existing piping by transmitting and receiving ultrasonic waves in the axial direction of the pipe material. be.

[Conventional technology]

Figure 4 is a cross-sectional view of a conventional ultrasonic probe shown in, for example, Ultrasonic Flaw Detection Method (published by Nikkan Kogyo Shimbun, 1972), and Figure 4a is a front cross-section of an angle probe. Figure 4b is a cross-sectional view of the angle probe.

In the figure, 1 is a flat plate-shaped transducer for transmitting and receiving ultrasonic waves, 2 is a plate-shaped transducer for fixing the transducer 1,
A plastic wedge is used to convert the longitudinal ultrasound generated from the transducer 1 into a transverse ultrasound, 3 is a sound absorbing material that absorbs unnecessary ultrasound, 4 is a probe case, and 5 is a tube material, etc. The test specimen 6 is a probe for increasing the propagation efficiency of ultrasonic waves, A is a longitudinal wave ultrasonic wave, and B is a transverse wave ultrasonic wave.

A conventional ultrasonic probe is constructed as described above, and the longitudinal ultrasonic wave A generated from the transducer 1 propagates within the wedge 2 and forms a Snell at the interface between the wedge 2 and the test specimen 5. According to the law, the transverse wave is converted into a transverse ultrasonic wave B, propagates forward of the test object 5, is reflected by a defect or discontinuous part in the test object 5, and is received by the transducer 1 again on the reverse path as a longitudinal wave ultrasonic wave A. be done.

At this time, since the conventional ultrasonic probe has only one transducer 1 in the probe case 4, the ultrasonic beam width in the direction corresponding to the circumferential direction of the test specimen 5 is If the test specimen 5 was to be inspected over its entire circumference in the tube circumferential direction, the number of scans of the ultrasonic probe would be extremely large, making it impossible to reduce the inspection time.

[Problems to be Solved by the Invention] As described above, in the ultrasonic probe equipped with only one transducer 1, the ultrasonic beam width corresponding to the circumferential direction of the test specimen 5 is narrow. There was a problem that the inspection time was increased.

In addition, in order to solve the above problem, even if a plurality of conventional ultrasonic probes are arranged in the circumferential direction of the test specimen 5, the transducer 1 of the conventional ultrasonic probe
Because it has a flat plate shape, the ultrasonic beam width is narrow;
There is a problem in that there is a region where the ultrasound beam widths do not overlap between the ultrasound probes, and even in the above case, shortening of the inspection time cannot be expected much.

This invention was made to solve the above problems, and it ensures that the ultrasonic beam widths of multiple transducers overlap, so that the ultrasonic beam width of one ultrasonic probe is the same as that of the test specimen. 120° in circumferential direction
The purpose is to obtain an ultrasonic probe that can secure the above area.

[Means for solving problems]

The ultrasonic probe according to the present invention has a plurality of curved transducers that diffuse ultrasonic waves arranged at a predetermined angle in the circumferential direction of a test specimen.

[Effect]

In this invention, the dimensions and radius of curvature of the transducer and the arrangement angle of the transducer are determined so that the spread of the ultrasound beam generated from the curved transducer completely overlaps with the ultrasound beam generated from the adjacent curved transducer. In addition, it is equipped with a number of curved transducers that can ensure an area where the total ultrasonic beam width of one ultrasonic probe is 120 degrees or more in the circumferential direction of the test specimen. This will greatly reduce inspection time.

〔Example〕

FIG. 1 is a sectional view of an ultrasonic probe showing an embodiment of the present invention, FIG. 1a is a front sectional view of the angle probe, and FIG. 1b is a cross-sectional view of the angle probe. It is a front view.

In the figure, 1a to 1d are curved transducers with curvatures that allow ultrasound to diffuse; 2 is a plastic wedge with a radius of curvature equivalent to that of the curved transducer; 3 is a wedge that absorbs unnecessary ultrasound waves. 4 is a probe case, 5 is a test piece such as a pipe material, 6 is a sound absorbing material to be
7 is a contact medium, 7 is a shoe for maintaining the gap between the wedge 2 and the test specimen 5, A is a longitudinal wave ultrasonic wave, B is a transverse wave ultrasonic wave, and A is a mutual arrangement angle of the curved surface transducers 1a to 1b.

FIG. 2 is a diagram showing the width of an ultrasonic beam formed by the ultrasonic probe according to the present invention.

In the figure, C is the ultrasonic beam width formed by the curved transducer 1a, D is the ultrasonic beam width formed by the curved transducer 1b, E is the ultrasonic beam width formed by the curved transducer 1c, and F is the ultrasonic beam width formed by the curved transducer 1c. The width of the ultrasound beam formed by the curved transducer 1d, H is the amplitude of the ultrasound signal,
θ is the circumferential angle of the test specimen 5.

FIG. 3 is a diagram showing the correlation between the dimensions, radius of curvature, and arrangement angle of the curved vibrator with respect to the outer diameter dimension of the test specimen.

In the figure, 1a and 1b are curved oscillators, 2 is a wedge, 5 is a specimen, A is the arrangement angle of the curved oscillator 1a, L is the dimension of the curved oscillator 1a, and l ₁ is the curved oscillator on the surface of the specimen 5. 1a is the ultrasonic beam width from the center of the curved surface transducer 1a, _l2 is the ultrasound beam width from the center of the curved surface transducer 1a on the inner surface of the test object 5, R is the radius of curvature of the curved surface transducer 1a, and _θ1 is the radiation from the curved surface transducer 1a. θ ₂ is the angle between the beam width l ₁ on the surface of the specimen 5 and the normal QO, and θ ₃ is the angle of the ultrasonic wave generated on the surface of the specimen 5.
θ ₄ is the angle of refraction of the ultrasonic wave in the specimen 5.

Here, the dimension L of the curved surface vibrator 1a is desirably 20 mm or less in order to prevent a decrease in defect production ability. In addition, the ultrasonic coverage range of one block of the ultrasonic probe is preferably 180 degrees or less for ease of attachment and detachment between the ultrasonic probe and the test specimen 5, and the data should be such that 360 degrees is divisible by an integer. It is desirable for processing, and in most cases 120° is one guideline.

Furthermore, the radius of curvature R of the curved transducer 1a should be such that the difference between the minimum and maximum distances of the ultrasonic waves propagating within the wedge 2 is approximately 1/4 to 1/2 of the wavelength within the wedge 2. This can prevent ultrasonic waves from rapidly diffusing and reducing defect detection ability.

Under the above preconditions, the dimension L of the curved surface vibrator 1a, the radius of curvature R of the curved surface vibrator 1a, the curved surface vibrator 1
The arrangement angle A of a can be determined from the following relationship.

W=t/cosθ _S ...(1) l ₂ = sinθ ₁ × (R+Δl) ...(2) θ ₂ = sin ^-1 (l ₁ /D/2) ...(3) θ ₃ =θ ₁ +θ ₂ ...(4) θ ₄ = sin ^-1 (V ₂ /V ₁ × sin θ ₃ ) ... (5) l ₂ ≒ l ₁ + tan (θ ₄ - θ ₂ ) × W ... (6) A = 2 ×sin ^-1 (l ₂ /D/2-t) ……(7) n≧/A ……(8) However, the assumption is that λ/4≦R ² −(L/2) ² ≦λ/2 ...(9) In equations (1) to (9), t: Thickness of the test specimen Δl: Length of the wedge V ₁ : Longitudinal sound velocity of the wedge V ₂ : Transverse sound velocity of the test specimen n: Curved surface vibrator length Number: Coverage range per probe block θ _S : Shear wave refraction angle in the specimen D: Outer diameter of the specimen W: 0.5 skip distance in the specimen λ: Represents the wavelength in the wedge.

In this example, when the outer diameter of the test body 5 is 60.5 mm, the dimension L of the curved surface vibrators 1a to 1d is 18 mm, the radius of curvature R of the curved surface vibrators 1a to 1d is 150 mm,
By selecting the arrangement angle A to be 30°, it was possible to transmit and receive ultrasonic waves over a tube circumference of about 120° of the test specimen 5 using the four curved transducers 1a to 1d.

That is, in the ultrasonic probe configured as described above, the longitudinal ultrasonic waves A generated from the curved transducers 1a to 1d that transmit and receive ultrasonic waves propagate while being diffused in the wedge 2, and further According to Snell's law, the transverse ultrasonic waves are further diffused and propagated in the tube circumferential direction in accordance with the outer diameter curvature of the test specimen 5.
Therefore, the dimension L of the curved surface vibrators 1a to 1d and the curved surface vibrators 1a to 1d are determined according to the outer diameter dimension of the test body 5.
The radius of curvature R of 1d and the curved surface vibrators 1a to 1d
By determining the arrangement angle A using equations (7) to (9), ultrasonic waves can be transmitted and received over a wide range in the circumferential direction of the test specimen 5 with a smaller number of curved transducers 1a to 1d. It becomes possible. Also, of course,
The ultrasonic beam widths H to D between the curved surface transducers 1a to 1d can easily be completely overlapped with amplitudes within -3 dB.

In addition, the curved surface vibrator 1a of the plastic wedge 2
The curved surface vibrator 1a is placed on the surface that 1d contacts.
~1d, and the surface facing the specimen 5 has a radius of curvature equal to the outer diameter of the specimen 5 plus a predetermined gap. There is. In other words, the outer diameter tolerance of the test specimen 5,
In order to increase the contact area between the wedge 2 and the test piece 5 when roundness etc. are taken into consideration, a shoe 7 is used between the wedge 2 and the outer surface of the test piece 5 to create a predetermined gap. is provided, and a contact medium is supplied to the gap to prevent poor acoustic coupling.

〔Effect of the invention〕

As explained above, this invention enables inspection in the circumferential direction of a test specimen by arranging a plurality of ultrasonic diffusion type curved surface transducers at a predetermined angle on a wedge corresponding to the circumferential direction of the test specimen. Since the range can be widened, the inspection time can be significantly shortened.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an ultrasonic probe according to the present invention, FIG. 1 a is a front cross-sectional view, FIG. 1 b is a cross-sectional view, and FIG. Figure 3 is a diagram showing the beam width, Figure 3 is a diagram showing the correlation between dimensions, radius of curvature, and arrangement angle of the curved transducer, Figure 4 is a cross-sectional view of a conventional ultrasound probe, and Figure 4a is a front cross-section. Figure 4b is a cross-sectional view. In the figure, 1 is a flat plate transducer, 1a to 1d are curved transducers, 2 is a wedge, 3 is a sound absorbing material, 4 is a probe case, 5 is a test specimen, A is a longitudinal wave ultrasound wave, and B is a transverse wave ultrasound wave. In the sound wave, H~D is the ultrasonic beam width, and A is the arrangement angle of the curved transducer. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In an angle probe that transmits and receives ultrasonic waves in the axial direction of a tube material, a plurality of ultrasonic diffusion type curved transducers arranged at a predetermined arrangement angle in the circumferential direction of the tube material, and the curved surface transducer and The surface with which the curved surface vibrator comes into contact with the tube material has a radius of curvature equivalent to the radius of curvature of the curved surface vibrator, and the surface facing the outer surface of the tube material has a curvature radius equal to the outer diameter of the tube material. An ultrasonic probe comprising a plastic wedge having a curvature corresponding to .