JPH0894595A - Longitudinal-ultrasonic-wave angle beam probe - Google Patents

Abstract

PURPOSE: To provide an ultrasonic probe whose defect detecting ability can be secured sufficiently to cover a broad range of the surface portion of a side on which the probe is placed. CONSTITUTION: A transmitting oscillator 3 and a receiving oscillator 4 are placed respectively in front and rear positions along the direction of propagation of an ultrasonic wave. When the transmitting oscillator 3 is placed in front of the receiving oscillator 4, the transmission angle θT of the ultrasonic wave becomes smaller than the reception angle θR of the wave, with the result that apparent angle is reduced. With this phenomenon, the efficiency with which the ultrasonic wave impinges on a test piece 8 from a transmitting wedge is enhanced, and thereby the rate at which a longitudinal ultrasonic wave 9 is transmitted back and forth through the test piece is made higher as a whole than if the transmission angle θT is the same as the reception angle θR.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the detection of defects in welds,
The present invention relates to an ultrasonic longitudinal wave bevel probe for an ultrasonic flaw detector, which mainly detects defects in the surface layer of a square billet or the like.

[0002]

2. Description of the Related Art FIG. 4 shows, for example, No. 2 of Subcommittee of Japan Non-Destructive Inspection Association, published in September 1982. 2931
It is a figure which shows the ultrasonic probe shown by "creeping wave and its application (1)", FIG.4 (a) is a perspective view, FIG.4 (b) is a side sectional view, FIG.4 (c). ) Is a rear sectional view. In the figure, 1 is a transmitting wedge, 2 is a receiving wedge, 3
Is a transmitting oscillator attached to the transmitting wedge 1, 4 is a receiving oscillator attached to the receiving wedge 2, and 5 is an ultrasonic wave propagating through the transmitting wedge 1 to the receiving wedge 2. Soundproof plate to prevent,
6 is a connector, 7 is a case, θ ₁ is an ultrasonic wave incident angle provided on the transmitting wedge 1, and θ ₂ is an ultrasonic wave receiving angle provided on the receiving wedge 2.

A conventional ultrasonic probe has one transmitting oscillator 3 and one receiving oscillator 4 as shown in FIG. 4, and the transmitting oscillator 3 and the receiving oscillator 4 generate ultrasonic waves. It is arranged in the left-right direction with respect to the propagation direction and without any deviation in the front-back direction. When ultrasonic waves are obliquely propagated to the test material by such an ultrasonic probe to perform ultrasonic flaw detection on the surface layer portion of the surface on which the ultrasonic probe is arranged, the ultrasonic refraction angle in the test material is About 70
It is necessary to set it to about 75 °. This state is shown in FIG.

FIG. 5 is a geometrical diagram of the bevel flaw detection method. In the figure, 1 is a wedge, 3 is a vibrator, 8 is a test body, A is an actual size of the vibrator 3, B is an apparent size of the vibrator 3, and S is an S size.
Is the surface of the test body 8, θ ₁ is the incident angle of the ultrasonic wave with respect to the normal line YY ′ orthogonal to the surface S of the test body 8, and θ _S is the normal line YY ′ orthogonal to the surface S of the test body 8. Is the refraction angle of the ultrasonic wave, and θ is the directivity angle of the ultrasonic wave.

Here, when the refraction angle θ _S is set to 75 °, the incident angle in the wedge 1 has the following value according to Snell's law. θ ₁ = sin ^-1 (sin 75 ゜ C ₁ / C ₂ ) {26.7} (1) where C ₁ = 2.748 km / S (longitudinal sound speed of wedge) C ₂ = 5 .9 km / S (longitudinal wave sound velocity of the test material) The directivity angle of the ultrasonic wave in the test material 8 can be obtained by the following equation. θ = K × λ / B (2) However, B = A × cos θ _S / cos θ ₁ (3) That is, in such a longitudinal wave bevel probe, the above (2 ),
As is clear from the equation (3), a large directivity angle θ can be obtained because the difference between the refraction angle θ _s and the incident angle θ ₁ is large, and a wide range from the surface layer of the test body 8 to a certain depth should be inspected. Is often used because it has the advantage that

[0006]

However, in this conventional longitudinal wave bevel probe, the defect detection ability in the surface layer portion (for example, about 3 to 10 mm) of the surface on which the probe is arranged is When the positional relationship between the child and the defect is relatively close (for example, 20 to 30)
mm), but the further the distance, the lower the ability to detect defects near the surface. That is,
The farther the relative position between the probe and the defect is, the larger the angle component of the ultrasonic directivity angle range is required. However, when the probe exceeds 80 °, the critical angle of the longitudinal wave is approached, so that the interface between the wedge and the copper is increased. The round-trip transmission rate of ultrasonic waves is sharply reduced, leading to a decrease in defect detectability.

The present invention has been made in order to improve the conventional drawbacks, and it is an object of the present invention to propose an ultrasonic probe capable of sufficiently ensuring defect detection capability over a wide range of the surface layer portion of the surface on which the probe is arranged. To aim.

[0008]

An ultrasonic longitudinal wave bevel probe according to the present invention is (θ _T + θ _R ) / 2 (θ _T is an ultrasonic wave transmission angle, and θ _R is an ultrasonic wave reception angle). ), The transmitting wedge and the receiving wedge are arranged at positions in the front-rear direction with respect to the propagation direction of the ultrasonic waves, and the opposite of the wedges for abutting the test body. The surface is provided with a transmitting oscillator and a receiving oscillator.

Further, according to the present invention, a transmitting wedge for fixing one transmitting oscillator at a predetermined angle, a receiving wedge for fixing two or more receiving oscillators at a predetermined angle, and each of the above One transmitter oscillator and two or more receiver oscillators are respectively provided on the opposite surfaces of the wedges that contact the test body, and two or more receiver oscillators are transmitted in the ultrasonic wave propagation direction. It is placed in front of the credit oscillator.

According to the present invention, a transmitting wedge for fixing two or more transmitting oscillators at a predetermined angle, a receiving wedge for fixing one receiving oscillator at a predetermined angle, and each of the above wedges. 2 or more transmitting transducers and 1
Each of the two receiving oscillators is provided, and the two or more transmitting oscillators are arranged in front of the receiving oscillator in the propagation direction of the ultrasonic waves.

[0011]

According to the present invention, the transmission rate of ultrasonic energy can be improved by setting the positional relationship between the transmitting oscillator and the receiving oscillator so that the apparent angle becomes small.

Further, according to the present invention, the apparent angle can be reduced by disposing two or more receiving oscillators in front of one transmitting oscillator.

The present invention includes two or more transmitting oscillators
The apparent angle can be made smaller by arranging them in front of the individual receiving oscillators.

[0014]

【Example】

Example 1. FIG. 1 is a sectional view of an ultrasonic probe showing an embodiment of the present invention. In the figure, 1 is a transmitting wedge, 2 is a receiving wedge, 3 is a transmitting oscillator, 4 is a receiving oscillator, 5 is a sound insulating plate, 6 is a connector, and 7 is a case. FIG. 2 is a conceptual diagram of an ultrasonic beam in steel of the ultrasonic probe according to the present invention. In the figure, 3 is a transmitting oscillator, 4 is a receiving oscillator, 9 is a longitudinal ultrasonic wave emitted from the transmitting oscillator 3, 10 is a transverse ultrasonic wave emitted from the transmitting oscillator 3,
Reference numeral 11 is a longitudinal ultrasonic wave received by the receiving vibrator 4, 12 is a transverse ultrasonic wave received by the receiving vibrator 4, θ _T is an ultrasonic wave transmission angle, and θ _R is an ultrasonic wave reception angle.

FIG. 3 is a graph showing the round-trip passage rate for longitudinal ultrasonic waves transmitted and received by the ultrasonic probe according to the present invention.
Is an apparent angle obtained by dividing the sum of the transmission angle θ _T and the reception angle θ _R by 2, H is the relative sensitivity, and 13 is the curve showing the round-trip passage rate.

In the figure, the round-trip passing rate is the ultrasonic energy applied from the transmitting wedge 1 to the test body 8 during transmission and the ultrasonic energy applied from the test body 8 to the receiving wedge 2 during reception. The longitudinal wave ultrasonic wave has a characteristic that the transmission rate of ultrasonic energy is the largest under the transmission / reception condition at 0 °, and the transmission rate of the ultrasonic energy decreases as the apparent angle β in transmission / reception increases. . Therefore, it is necessary to configure the positional relationship between the transmitting oscillator 3 and the receiving oscillator 4 so that the apparent angle β becomes small.

That is, as described above, the transducer 3 for transmission and the transducer 4 for reception are provided at the front and rear positions with respect to the propagation direction of ultrasonic waves.
In the ultrasonic probe in which is arranged, when the transmitting transducer 3 is arranged in front of the receiving transducer 4, the ultrasonic transmitting angle θ _T is always smaller than the receiving angle θ _R , and as a result, The apparent angle β becomes smaller. This phenomenon improves the efficiency of incidence of ultrasonic waves from the transmitting wedge 1 to the test body 8. Therefore, compared with the case where the transmitting angle θ _T and the receiving angle θ _R are the same, the round-trip passing rate of the longitudinal ultrasonic waves 9 is higher. Will be improved. In particular, this characteristic appears as a more significant difference when the relative position between the probe and the defect is far and the defect is closer to the surface of the test body 8 on which the probe is arranged, and the defect signal can be detected at a large level.

The longitudinal wave bevel probe has the following advantages. That is, the transverse ultrasonic wave 10 effectively acts on the defect existing directly below the transmitting oscillator 3, and this also enables the defect signal to be detected at a large level.
It is possible to significantly improve the S / N ratio.

The probe according to the present invention is considerably effective for a flaw detection system in which the probe or the test body is not scanned in a direction parallel to the propagation direction of ultrasonic waves, that is, for an automatic flaw detector.

Example 2. By the way, in the above description, the example in which the two transducers for transmission are arranged in front of the transducer for reception is shown. However, conversely, two transducers for reception are arranged in front of the transducer for transmission, or for transmission / reception. Since the similar result can be obtained even if the combination of the number of oscillators is changed, the application of the present invention is inevitable.

Incidentally, as a probe in which a transducer is arranged at a position in a front-rear direction with respect to the direction of propagation of ultrasonic waves, the actual probe 52 is used.
There is one disclosed in Japanese Patent Laid-Open No. 115272, but in this probe, a transducer is arranged in a front-rear position in order to reduce an apparent angle β and improve a passing rate of ultrasonic energy. is not.

[0022]

EFFECTS OF THE INVENTION The present invention is (θ _T + θ _R ) / 2 (θ _T
Is the transmission angle of the ultrasonic wave, and θ _R is the reception angle of the ultrasonic wave). The transmission wedge and the reception wedge are arranged at positions in front of and behind the propagation direction of the ultrasonic wave so that the apparent angle becomes small. In order to reduce the inspection time, which is a problem especially in the automatic flaw detector, by providing the transmitting oscillator and the receiving oscillator on the opposite surfaces of the wedges that come into contact with the test body, the ultrasonic wave is used. In the flaw detection method in which the probe is not scanned back and forth with respect to the propagation direction of 1, the high S / N ratio can be secured over a wide range of the surface layer of the test body.

Further, according to the present invention, a transmitting wedge for fixing one transmitting oscillator at a predetermined angle, a receiving wedge for fixing two or more receiving oscillators at a predetermined angle, and each of the above One transmitter oscillator and two or more receiver oscillators are respectively provided on the opposite surfaces of the wedges that contact the test body, and two or more receiver oscillators are transmitted in the ultrasonic wave propagation direction. By arranging it in front of the credit oscillator, the same effect as above can be obtained.

According to the present invention, a transmitting wedge for fixing two or more transmitting oscillators at a predetermined angle, a receiving wedge for fixing one receiving oscillator at a predetermined angle, and each of the above wedges. 2 or more transmitting transducers and 1
The same effect as described above can be obtained by providing each of the receiving oscillators and arranging the two or more transmitting oscillators in front of the receiving oscillator in the propagation direction of ultrasonic waves.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a probe showing an embodiment of the present invention.

FIG. 2 is a conceptual diagram of an ultrasonic beam according to the present invention.

FIG. 3 is a diagram showing a round-trip passage rate of longitudinal ultrasonic waves in the present invention.

FIG. 4 is a perspective view and a sectional view showing a conventional ultrasonic probe.

FIG. 5 is a geometrical diagram of the bevel flaw detection method.

[Explanation of symbols]

1 transmitting wedge, 2 receiving wedge, 3 transmitting oscillator, 4
Receiving oscillator.

Claims (3)

[Claims] 1. The propagation direction of ultrasonic waves is reduced so that the apparent angle indicating (θ _T + θ _R ) / 2 (θ _T is the ultrasonic wave transmission angle and θ _R is the ultrasonic wave reception angle) is small. On the other hand, the transmission wedge and the reception wedge are arranged at the positions of the front-rear relationship,
An ultrasonic longitudinal wave bevel probe, characterized in that a transmitting oscillator and a receiving oscillator are respectively provided on the opposite surfaces of the respective wedges that come into contact with the test body. 2. A transmitting wedge for fixing one transmitting oscillator at a predetermined angle, a receiving wedge for fixing two or more receiving oscillators at a predetermined angle, and a test for each of the wedges. One transmitting oscillator and two or more receiving oscillators are provided on the opposite surface that contacts the body, and two or more receiving oscillators are provided from the transmitting oscillator in the ultrasonic wave propagation direction. An ultrasonic longitudinal wave bevel probe characterized by being placed in front. 3. A transmitting wedge for fixing two or more transmitting oscillators at a predetermined angle, a receiving wedge for fixing one receiving oscillator at a predetermined angle, and a test for each of the wedges. Two or more transmitting oscillators and one receiving oscillator are respectively provided on the opposite surface contacting the body, and the two or more transmitting oscillators are receiving oscillators in the propagation direction of ultrasonic waves. An ultrasonic longitudinal wave bevel probe characterized by being arranged further forward.