JPH0675062B2 - Ultrasonic probe device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultrasonic probe device for performing vertical flaw detection on a material to be inspected by a water immersion method using, for example, a pulse reflection method.

[Conventional technology]

FIG. 4 is a diagram of a conventional ultrasonic probe apparatus shown in, for example, the ultrasonic flaw detection method (published by Nikkan Kogyo Shimbun, 1974).
In the figure, (1) is the material to be tested, (2) is an ultrasonic probe whose acoustic radiation surface and transducer are flat, (3) is an acoustic coupling material (for example, water), and (4) is the material to be tested ( 1) Internal defects,
(5) is an ultrasonic beam, S is a surface reflection wave of the test material (1), F is a defect reflection wave inside the test material (1), and B is a bottom reflection wave of the test material (1). is there. Further, FIG. 5 is a flaw detection figure by the conventional ultrasonic probe device. In the figure, (7) is a flaw detection gate for flaw detection on the material (1), T ₁ is the first transmission pulse, T ₂ is the second transmission pulse, Tn is the nth transmission pulse, and is the transmission pulse. , S ₁ is the first surface reflection wave of the test material (1) with respect to the transmission pulse T ₁ , and the following S ₂ , S ₃ , S ₄ , S ₅ , ... Sn are respectively the second time, Third
The 4th time, 4th time, 5th time, ... The nth surface reflected wave, B ₁ -S ₁ is the _first of the test material (1) for the surface reflected wave S 1.
B ₂ -S ₁ …… Bn-S ₁ is the _second bottom reflected wave of the test material (1) against the surface reflected wave S ₁ …… the nth bottom reflected wave, B ₁ -S ₂ , B ₂ ‐S ₂ …… Bn-S ₂ , B ₁ ‐S ₃ …… Bn-
S ₃ , B ₁ -S ₄ ...... Bn-S ₄ , Bn-S ₅ ...... Bn-Sn are the nth bottom reflected waves of the test material (1) with respect to the nth surface reflected wave Sn, respectively. F is the defect reflection wave inside the test material (1) with respect to the _first surface reflection wave S ₁ , and F ′ is the second surface reflection wave.
It is a defect reflected wave inside the test material (1) with respect to S ₂ . As shown in the figure, in the first transmission pulse T ₁ , multiple echoes (S ₁ , S ₂ ... Sn) of the surface reflection wave of the test material (1) and the defect reflection wave inside the test material (1) Multiple echoes (B ₁ -S ₁ , B ₂ -S ₁ , of the bottom reflected waves of the test material (1) for (F, F ′) and the respective surface reflected waves (S ₁ , S ₂ , ... Sn) …
… Bn-Sn) and many other reflected waves appear. The multiple echoes (S ₁ ... Sn, B _1- S ₁ ... Bn-Sn) appear in the same manner at intervals of the repetition time t for each transmission pulse (T ₁ , T ₂ , ... Tn).

The conventional ultrasonic probe device is configured as described above, and when it is automated, repeatedly transmits the transmission pulse T and operates the test material (1) or the ultrasonic probe (2) to perform the test. Ultrasonic flaw detection is performed on the entire surface of the material (1). In addition, the repetition time t of the transmission pulse T depends on the relative moving speed of the test material (1) and the ultrasonic probe (2).
Has been decided. That is, in order to reduce the flaw detection processing capability of the test material (1), it is necessary to shorten the repetition time t of the transmission pulse T, so that the surface reflected wave S ₁ generated by the _first transmission pulse T ₁ is generated. To Sn, and the bottom reflected wave B ₁
-S ₁ to Bn-It is necessary to transmit the transmission pulses T ₂ to Tn from the second time onward before Bn-Sn is completely extinguished. In that case, the surface reflection wave S _{1 from} the transmission pulse T ₁ from the first time is transmitted. As the reverberation echo between the bottom surface reflected wave B ₁ and the bottom reflected wave B ₁ -S ₁ , the surface reflected wave Sn and the bottom reflected wave Sn-Bn due to the transmission pulses T ₂ to Tn after the second time appear. Therefore, the surface reflected wave Sn and the bottom surface reflected wave Sn-Bn are erroneously detected as the defect reflected wave F.

[Problems to be Solved by the Invention]

As described above, in the ultrasonic probe device having only the water which is the acoustic coupling material (3) between the test material (1) and the ultrasonic probe (2) having a flat transducer and acoustic emission surface, The reflected wave S on the surface of the test material (1) is reflected by about 95% and is reflected by about 60% on the surface of the ultrasonic probe (2), so the ultrasonic probe (2) and the test material (1 ) Attenuates only about 5 to 6 dB for each round trip. Therefore, the defect detectability normally required (for example, φ
_When the reduction amount of the reverberation echo Sn, Bn-Sn with respect to the first surface reflected wave S _{1 is} calculated from ₁ lateral hole defect S / N ≧ 20 dB), it is necessary to be -60 dB or less. That is, if the second transmission pulse T ₂ is generated before the time elapsing 10 to 12 times the distance between the ultrasonic probe (2) and the test material (1) elapses, the reverberation echo is generated. As a result, there arises a problem that Sn and Bn-Sn appear as pseudo echo F. In particular, this problem is a fatal drawback in an automatic flaw detection device with a high flaw detection processing speed.

The present invention has been made to solve the above problems, and has an ultrasonic probe having a convex vibrator and a convex acoustic emission surface, and further includes a test material and an ultrasonic wave. An acrylic resin divider plate with a uniform thickness is placed in the acoustic coupling part between the probe and the ultrasonic beam direction.
The purpose is to prevent reverberation echo and shorten the repetition time of the transmission pulse by providing the angle within the range of ° to 55 °.

[Means for Solving the Problems]

An ultrasonic probe device according to the present invention includes an ultrasonic probe in which a transducer and an acoustic radiation surface have a convex shape, and a portion of an acoustic coupling material between a test material and the ultrasonic probe. In addition, a threshold plate made of acrylic resin having a uniform thickness is provided within an angle range of 35 ° to 55 ° with respect to the traveling direction of the ultrasonic beam.

[Action]

In the present invention, an acrylic resin partition plate having a uniform thickness is provided at a portion of the acoustic coupling material between the test material and the ultrasonic probe at 35 ° to 55 ° with respect to the traveling direction of the ultrasonic beam. By providing the ultrasonic probe within the angular range and by making the acoustic emission surface of the ultrasonic probe and the shape of the transducer convex, the total number of ultrasonic waves reciprocating once between the ultrasonic probe and the test material It is possible to increase the amount of attenuation and shorten the transmission pulse repetition time.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention. (1)
And (3) to (5) are exactly the same as the conventional device shown in FIG. In the figure, (6) is a separator plate made of acrylic resin according to the present invention, (8) is a convex vibrator,
Reference numeral (9) is an ultrasonic probe having a convex oscillator (8) and having a convex sound emitting surface.

FIG. 2 is an enlarged view of the vicinity of the plate (6) in FIG. In the figure, X ₁ is the ultrasonic beam before passing through the plate (6), X ₂ is the ultrasonic beam after passing through the plate (6), X ₃ is the ultrasonic beam X ₁ is the plate (6) The ultrasonic beam reflected by the surface, y ₁ is a transverse ultrasonic wave passing through the inside of the plate (6), α is the incident angle of the ultrasonic beam X _{1 to} the plate (6), β is the plate (6) ) Internal refraction angle, θ is an angle formed by the plate (6) and the ultrasonic beam (5).

FIG. 3 shows the ultrasonic probe apparatus configured as described above, which is used for the test material (1) by the water immersion method using the pulse reflection method.
It is a flaw detection figure when vertical flaw detection is performed. In the figure, (7) and the symbols (S ₁ , S ₂ , S ₁ -S ₂ ...) in the figure are the fifth
It is exactly the same as that shown in the figure.

In the ultrasonic probe device configured as described above, the portion of the acoustic coupling material (3) between the test material (1) and the ultrasonic probe (9) is made of acrylic resin having a uniform thickness. Θ = 35 with respect to the traveling direction of ultrasonic beam (5)
If it is installed within the angle range of 55 ° to 55 °, the ultrasonic beam (5) generated from the ultrasonic probe (9) is x ₁ , x ₂ , x ₃ , y
It can be distinguished as ₁ . Here, assuming that the sound velocity of water is C and the transverse wave acoustic velocity of acrylic resin is Cs, equations (1) and (2) hold between α, β, and θ.

Here, if the sound velocity of water: C ≈ 1480 m / s (20 ° C) and the shear wave velocity of acrylic resin ≈ 1420 m / s, equation (1) becomes three equations.

sin α ≒ sin β ………… (3) From the equation (3), the ultrasonic beam travels almost linearly as x ₁ → y ₁ .

Next, regarding the level of x ₃ which is the reflection characteristic in the plate (6), the reflectance γ is calculated by Eq. (4), where z _{1 is} the acoustic impedance of water and z ₂ is the transverse impedance of acrylic resin. To be

However, Here, C _D is the longitudinal wave sound velocity in the acrylic resin (6), ρ ₁ is the density of the acoustic coupling material (3), ρ ₂ is the density of the acrylic resin (6), and γ is the longitudinal direction in the acrylic resin (6). Wave refraction angle.

From the expressions (2) and (4), the reflectance γ of x ₃ is θ = 35 ° to 55
Within the angle range of °, it is about 10% or less. That is, 90% or more of the ultrasonic beam x ₁ travels as the ultrasonic beam y ₁ . Further, since the thickness of the dividing plate (6) is uniform, the relationship between the ultrasonic beams y ₁ and x ₂ is the same as above.

Next, the attenuation of the ultrasonic beam will be described. The ultrasonic beam y ₁ inside the divider plate (6) is propagated by the transverse wave in the acrylic material. Therefore, comparing the attenuation of ultrasonic waves propagating in water with the attenuation of ultrasonic waves propagating by transverse waves in acrylic material is about 15 times, and the attenuation is greater when propagating in acrylic material.

According to the above description, an acrylic plate having a uniform thickness is provided in the acoustic coupling material (3) between the test material (1) and the ultrasonic probe (9) in the traveling direction of the ultrasonic beam (5). , Θ = 35 ° ~
The siding plate (6) provided within an angle range of 55 ° makes it possible to:

(I) The traveling direction of the ultrasonic beam (5) does not change.

(II) It is possible to reduce the sound pressure level by about 5 to 10 dB each time the plate (6) is passed.

In addition, by making the shape of the transducer (8) convex and further making the acoustic radiation surface convex, about one reciprocation between the ultrasonic probe (9) and the test material (1) It is possible to reduce the sound pressure level by 10 dB.

From the above, according to the present invention, as shown in FIG. 3, the number of multiple echoes of the reflected wave of the material (1) to be inspected by the _first transmission pulse T ₁ is reduced and the repetition time t of the transmission pulse T is shortened. Made it possible.

Although the present embodiment has been described by using the example of the acrylic resin plate, the same effect can be obtained even if the angle condition is slightly different even if the acoustic wave velocity of the acoustic coupling material is the same as that of a plastic or rubber material. Therefore, the application of the present invention is unavoidable.

〔The invention's effect〕

As described above, according to the present invention, a portion of the acoustic coupling material between the test material and the ultrasonic probe has a uniform thickness and a transverse wave sound velocity is approximately the same as the sound velocity of the acoustic coupling material. To reduce the repetition time of the transmission pulse by providing it within the angle range of 35 ° to 55 ° with respect to the traveling direction and by making the acoustic emission surface of the ultrasonic probe and the shape of the transducer convex. In the automation of the ultrasonic flaw detector, there is an effect that the treatment time for the material to be inspected is shortened and the flaw detection density is increased to enable the velocity flaw detection and the density flaw detection.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention, FIG. 2 is a partially enlarged view of FIG. 1, and FIG. 3 is a flaw detection figure in the present invention.
FIG. 4 is a diagram showing a conventional ultrasonic probe device, and FIG. 5 is a flaw detection figure in the conventional ultrasonic probe device. In the figure, (1) is the test material, (2) is the ultrasonic probe,
(3) is an acoustic coupling material, (4) is a defect inside the test material,
(5) is an ultrasonic beam, (6) is a plate, (7) is a flaw detection gate, (8) is a convex transducer, and (9) is an ultrasonic probe with a convex acoustic emission surface. . The same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An ultrasonic probe apparatus of a water immersion method in which a distance space is provided between an ultrasonic probe and a test material, and the space portion is filled with an acoustic coupling material such as water or oil, An ultrasonic probe having a convex vibrator in which ultrasonic waves are diffused and having a convex acoustic emission surface, and a thickness on the ultrasonic propagation path between the ultrasonic probe and the test material is An ultrasonic probe characterized in that a threshold plate, which is uniform and has a transverse sound velocity substantially equal to that of the acoustic coupling member, is provided within an angle range of 35 ° to 55 ° with respect to the traveling direction of the supersonic beam. Child device.