JPH04166761A - Ultrasonic probe - Google Patents

Abstract

PURPOSE:To obtain resolving power having flaw detection dimensions designated in two perpendicularly crossing directions within a material to be inspected by providing a piezoelectric vibrator of which the ultrasonic transmitting the receiving surface is spherical and the opening part is rectangular. CONSTITUTION:A square opening part 6 is provided in front of a case 2 emitting ultrasonic waves of an ultrasonic probe 1. A back plate 5 composed of material quality large in attenuation at the time of the propagation of ultrasonic waves is provided in the case 2 and the front thereof forms a concaved spherical surface. A piezoelectric vibrator 3 has high frequency and wide-band characteristics and is easily processed into an arbitrary shape and approximate to water in acoustic impedance and a polymer piezoelectric body of a small value is provided in front of the back plate 5 and electrodes 7, 8 are provided on both surfaces of the vibrator 3. The vibrator 3 has a radius R of curvature and the dimension of the opening part 6 is D and, when the wavelength of ultrasonic waves is lambda, predetermined ultrasonic beam is formed.

Description

[Detailed Description of the Invention] ] Industrial Application] The present invention applies to an ultrasonic probe used, for example, in detecting defects in a test material in a liquid, particularly in the form of an ultrasonic beam in orthogonal directions. It is something.

I. Conventional technology: A specimen material and an ultrasonic probe are placed separately in a liquid, and ultrasonic waves are used to detect defects in the specimen material.

Fig. 5 is an example of an ultrasonic beam type using a conventional piezoelectric vibrator, 4 is a protective layer, 5 is a back plate that attenuates ultrasonic waves, 13 is a piezoelectric vibrator, and R is the ultrasonic radiation surface of the piezoelectric vibrator 13. The radius of curvature, D, is the opening dimension of the piezoelectric vibrator 13.

The conventional ultrasonic probe is constructed as described above, and the ultrasonic wave transmitting/receiving surface is a circular piezoelectric vibrator 3 having a spherical surface with a radius of curvature R, and the ultrasonic wave transmitting/receiving surface is provided with a protection 14 and the back plate is provided with a back plate. 5 is provided. When the aperture size of the piezoelectric vibrator 3 is made small, an ultrasonic beam with a wide beam width at the focal position is formed.

Fig. 6a is another example of ultrasonic beam formation of a conventional piezoelectric vibrator, Fig. 6 is an example of an ultrasonic directing load in a direction orthogonal to Fig. 6a, and the square piezoelectric vibrator 13 is unidirectional. The ultrasonic beam is formed by the cylindrical curved surface as shown in FIG. 6a. Further, as shown in FIG. 6, the ultrasonic waves emitted from the piezoelectric vibrator 13 in a direction perpendicular to this direction are not focused and are emitted uniformly from the entire piezoelectric vibrator 13. Therefore, the ultrasonic beam at the focal position is line focused in two orthogonal directions.

The ultrasonic probe equipped with the ultrasonic beam described above is used to detect defects in a test material that is immersed in a liquid.

1 Problem to be Solved by the Invention 1 In the conventional ultrasonic probe as described above, the ultrasonic beams emitted from the circular piezoelectric vibrator 13 whose ultrasonic wave transmitting/receiving surface is spherical are focused and orthogonal to each other. The same directional characteristics are shown in the two directions.

Therefore, for example, when detecting defects in a tube or rod conveyed by a rotating feed mechanism underwater, when the defect detection dimensions differ in the radial direction and the length direction, the defect cannot be detected with high sensitivity at a resolution that meets the above requirements. Furthermore, the moving pitch of the material to be inspected becomes smaller, and inspection takes more time.

Also, a rectangular piezoelectric vibrator 13 having a unidirectional or cylindrical curved surface
The ultrasonic beam emitted from the - direction is focused in the - direction, but the ultrasonic beam in the direction perpendicular to this is not focused. Therefore, in the two orthogonal directions, the specimen is defective with the specified defect size, that is, resolution. Detection cannot be performed, and the defect signal-to-noise ratio (S/normal) also becomes smaller.

Unless an ultrasonic beam of a predetermined width is obtained in the direction of conveyance of the material to be inspected, it is impossible to match the moving pitch of the material to be inspected, so defects often cannot be detected efficiently over the entire surface.

This invention was made to solve these problems, and is an ultrasonic probe that can obtain resolution according to specified defect detection dimensions in two orthogonal directions within a material to be inspected, and can efficiently detect defects. The purpose is to heal.

] Means for Solving the Problems 2 This Invention I This ultrasonic probe is provided with a piezoelectric vibrator having a spherical ultrasonic wave transmitting/receiving surface and a rectangular opening.

1 Effect] In the present invention, an ultrasonic probe in which the ultrasonic wave transmitting/receiving surface has a spherical shape and uses a high-frequency piezoelectric vibrator has a rectangular aperture so that the formed ultrasonic beam is Depends on dimensions.

That is, as the aperture size increases, the beam is focused and the beam width becomes narrower. However, as the aperture size becomes smaller, the beam width becomes wider.

Therefore, the ultrasonic probe, which has a rectangular opening, emits ultrasonic waves having beam widths in two orthogonal directions. Since the goal has a spread, two orthogonal
A slough of lysin with different lengths is formed at the focal position in the direction.

By selecting the radius of curvature of the spherical surface and the dimensions of the opening using the above-mentioned deformable polymer piezoelectric material or ceramic piezoelectric material, the dimension of the line focus can be matched with the defect detection dimension, By forming an ultrasonic beam that matches the defect detection dimensions of the material to be inspected, proper inspection with excellent signal-to-noise conversion can be performed.

In addition, inspection efficiency can be improved by matching the movement pitch of the specimen to be inspected and the ultrasonic beam.

``Embodiment'' An embodiment of the present invention will be described in detail with reference to the accompanying drawings.g Fig. 1a is a front view showing an embodiment of the invention; It is an A sectional view.

In the figure, 4.5 is the same as the conventional probe mentioned above, and 1
2 is an ultrasonic probe, 2 is a case, 3 is a piezoelectric vibrator using a polymeric piezoelectric material, 6t is an opening for emitting ultrasonic waves, and 7 is an opening attached to one side of the piezoelectric vibrator 3. 1 electrode,
8 is a second electrode attached to the other surface of the piezoelectric vibrator 3; 9
10 indicates a sorting line, and 10 indicates a cable.

In the ultrasonic probe configured as described above, a rectangular opening 6 is provided in the case 2 for emitting ultrasonic waves of the ultrasonic probe. Inside the case 2 is a back plate 5 made of a material that exhibits large attenuation during ultrasonic propagation, and the front surface of the case 2 has a concave spherical surface.

The piezoelectric vibrator 3 has high-frequency and wide-band characteristics, can be easily processed into any shape, and has a small acoustic impedance similar to that of water. A first electrode 7 and a second electrode 8 are attached. Further, on the front surface of the piezoelectric vibrator 3, a protective cover 4 made of, for example, polyethylene, polyimide, polyester, or polypropylene film is provided for waterproof construction and acoustic impedance matching with water. The opening 6 of the spherical piezoelectric vibrator 3 has a rectangular shape.

Via the lead wire 8 and cable 10, the piezoelectric vibrator 3 is energized and signals are transmitted from the piezoelectric vibrator 3.

FIG. 2 shows an A-A main part diagram of FIG. The ultrasonic beam width d-3 of 13 dB formed at the focal position formed by the ultrasonic probe 1 is shown as d-3.

When the frequency and the radius of curvature R of the spherical surface are constant, the width of the ultrasonic beam formed at the focal position is a function of the aperture size of the aperture 6.

FIG. 3 shows a cross-sectional view of the main part at B-8 in FIG. It is composed of

In the above, when the aperture size of the aperture 6 becomes smaller, the ultrasonic beam width CL3 becomes wider. The ultrasonic beams formed by the ultrasonic probe unit having six rectangular openings are different in two orthogonal directions.

In addition, since the polymer piezoelectric material (with high frequency and wide band loading) is energized by a signal with a short pulse width, the resolution of defect detection near the surface of the workpiece and in the depth direction can be improved.

For example, under water (velocity of sound 1500 m s), opening size D of opening 6 is 5.1 mm x 1 Q mm, frequency 2
Ultrasonic beam formed by piezoelectric vibrator 3 of 0\IH2 with a focal length of 10 mm (horizontal beam width d1 = 0
．． The beam width in the vertical direction is 15 mm, and the width of the beam in the vertical direction is 0.077 mm, and an ultrasonic probe measuring 80 μm x 150 μm can be obtained with defect detection dimensions in two orthogonal directions.

Fig. 4a is a side view showing an example of water immersion flaw detection, and the fourth section is a front view of Fig. 4a. A tube or a round bar as the material 10 is immersed, and the material 10 to be tested is conveyed in the direction of the arrow while rotating.

The two ultrasonic beams emitted from the ultrasonic probe unit (are the beam width d1 in the transport direction of the specimen 10 placed at the focal point distance F, the beam width d2 in the direction orthogonal to this, and a
= When the pulse width of the wave pulse varies, the specimen 1 to be transported
When inspecting the entire surface of Q, the moving pinch is the same as Fi] (j
1, and by matching the beam width dimension in the transport direction (orthogonal to this) with the defect detection dimension, the inspection efficiency of the inspected material 10 can be improved, and the signal-to-noise ratio is improved, making defect detection easier. You can also improve your manpower.

Furthermore, in the depth direction, defects with low resolution can be detected from near the surface.

As mentioned above, the high-frequency polymer piezoelectric material, which can be easily adapted to any shape, has a spherical ultrasonic wave transmitting/receiving surface and a rectangular opening 6, so if the radius of curvature of the spherical surface is By setting the aperture to a predetermined size, it is possible to match the dimensions of the mid-beam center line focus in two orthogonal directions to the defect detection dimensions.

In addition, the signal-to-noise ratio and improved detection of micro-defects in small-diameter pipes and the like can be easily achieved using pulse-width ultrasonic pulses.

Further, even if one ceramic piezoelectric is used as the piezoelectric vibrator 3, the same operation can be performed.

1. Effects of the invention] As described above, this invention uses a simple structure in which the aperture of a high-frequency piezoelectric vibrator having a curved surface shape is rectangular. Can be matched to detection dimensions.

By matching the movement pitch of the material to be inspected and the ultrasonic beam width, inspection over the entire surface can be performed efficiently.

Furthermore, the improved signal-to-noise ratio enables the detection of small defects.

This method has the effect of improving the resolution of defect detection in the depth direction of the test material by using ultrasonic pulses with a short pulse width.

[Brief explanation of drawings]

Fig. 1 is a front view showing an example of this explanation, Fig. 2 is a sectional view taken along the line A-A in Fig. 1, Fig. 2 is a sectional view taken along the line A-A in Fig. B-B main part stone plan of Figure 1a, Figure 4a
is a side view showing an example of water immersion flaw detection, and Fig. 4 b1 is the 4th section a.
5 is an example of ultrasonic beam formation using a conventional piezoelectric vibrator. FIG. 6a is another example of ultrasonic beam formation using a conventional piezoelectric vibrator. Ultrasonic pulses in the orthogonal direction [This is a raw example. In the figure, 3 is a piezoelectric vibrator, 4 is a protective layer, 5 is a back plate, and 6
is the opening, R is the radius of curvature, and D is the opening dimension. Note that the same symbols in each section indicate the same or corresponding parts. Patent applicant: Tokimetsuku Co., Ltd. BL=- 3, Piezoelectric film (gravitational force 4, protective layer 5, back plate 6, opening width, curvature radius D, opening size), Figure 2, Figure 3, Figure 4, Figure 8) ＼ Figure 6a Figure 6b

Claims (4)

[Claims] (1) In an ultrasound probe equipped with a protective layer on the front surface of a piezoelectric vibrator that transmits and receives ultrasound waves and a back plate that attenuates ultrasound waves on the back surface, the ultrasonic wave transmission and reception surface is spherical and the opening is An ultrasonic probe characterized by being equipped with a rectangular piezoelectric vibrator. (2) The ultrasonic probe according to claim 1, wherein the piezoelectric vibrator is a polymeric piezoelectric material. (3) The ultrasonic probe according to claim 1, wherein the piezoelectric vibrator is a ceramic piezoelectric body. (4) The ultrasonic probe according to claim 1, wherein the spherical surface is a concave surface.