JPH0823551B2 - 2-part vertical probe - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultrasonic two-divided vertical probe for an ultrasonic flaw detector that nondestructively inspects internal defects such as plate materials, pipe materials, and bar materials. It is a thing.

[Conventional technology]

FIG. 3 is a sectional view and a flaw detection waveform diagram of a conventional two-division vertical probe shown in, for example, the ultrasonic flaw detection method (published by Nikkan Kogyo Shimbun, 1974).

FIG. 4 is a diagram showing the beam width characteristic of the conventional two-division type probe, the sound pressure distribution within the beam width, and the array of the probes.

In the figure, (1) is a flat plate transducer that transmits ultrasonic waves,
(2) is a flat plate transducer for receiving ultrasonic waves, (3) is a wedge on the transmitting side, (4) is a wedge on the receiving side, (5) is an acoustic shield plate made of cork material, and (6) is epoxy. Potting material such as resin, (7) specimen, (8) defects near the surface, (9) defects near the bottom surface, (10) ultrasonic waves for detecting defects (8) near the surface Beam, (11) is an ultrasonic beam for detecting defects (9) close to the bottom surface, (12
a) to (12c) are two-segment vertical probes, and (13a) to (1
3c) is an effective beam width, (14a) and (14b) are effective beam widths (13a) and (13b) and (13b) and (13c), respectively. Approx. 15 mm
Sound pressure distribution within the effective beam width (13a) in the vicinity, (17) Sound pressure distribution within the effective beam width (13a) around 40 mm below the surface, (18) Effective beam width around 60 mm below the surface ( 13a) sound pressure distribution, T is transmitted pulse, S is surface echo,
F ₁ is a reflection echo from a defect (8) near the surface, F ₂ is a reflection echo from a defect (9) close to the bottom surface, and B is a bottom surface echo.

The conventional two-division type vertical probe is configured as described above, and the ultrasonic waves generated from the transmitting flat plate transducer (1) enter the test body (7) via the wedge (3). Propagated. The ultrasonic waves are reflected by the defects (8), (9) and the bottom surface of the test body (7) and are received by the receiving flat vibrator (2) via the receiving wedge (4). It

Further, as shown in FIG. 3, the flaw detection waveform at this time is such that the reflection echoes from the respective reflection sources are sequentially observed after the transmission pulse T in a form corresponding to the propagation time of the ultrasonic waves.

In order to further improve the efficiency of inspection, a wide range of inspections are performed at once by arranging a plurality of two-division vertical probes as shown in FIG.

Also, since the two-division type vertical probe is excellent in detectability of defects (8) near the surface due to the feature that the surface echo S can be made small, the rear side of the flat plate transducers (1) and (2) has a special Damping is not considered, and usually only potting (6) such as epoxy resin is applied.

[Problems to be Solved by the Invention]

When the transmitting / receiving oscillators (1) and (2) are flat plates as described above, the effective beam widths (13a) to (13c) become narrower as they approach the near field limit distance x ₀ . There is a problem that undetected areas (14a) and (14b) are generated. In addition, in order to eliminate the undetected areas (14a) and (14b), it is necessary to reduce the array pitch of the two-division type probes (12a) to (12c) and increase the number, so the cost is increased. There is a problem of becoming high, and the effective beam width near the surface (13a)
(13c) has a large overlap rate, and there is a problem that efficient inspection cannot be performed.

Furthermore, since no special damping is applied, the reflection echo F ₂ from the defect (9) close to the bottom surface is not separated from the bottom surface echo B, which makes it difficult to detect, and the sound pressure distribution within the effective beam width There are problems such as large changes and poor reproducibility of defect detectability.

The present invention has been made to solve the above problems, and has a convex lens shape on the wedge and the oscillator (a shape in which ultrasonic waves are diffused).
By providing a curvature of 1 and a damper whose main component is a high-density metal powder with high specific gravity on the back side of the above-mentioned curvature oscillator, a wide effective beam width is secured up to a long distance, and distance resolution is further improved. The purpose is to obtain a two-part vertical probe.

[Means for solving the problem]

The two-part vertical probe according to the present invention includes a transmitting curved surface transducer that is curved along the shield plate on the transmitting side so as to have a convex shape with respect to the side on which the test piece is installed, and the transmitting side transducer. The high-density transmission damper made of a metal with a high specific gravity, which is provided in contact with the back surface of the curved curved oscillator, and the transmitting damper provided on the side where the test body is installed, in contact with the curved curved oscillator for transmission. A curved receiver for reception, which is provided with a wedge and is curved along the shield plate so as to be convex toward the side on which the test body is installed, and a rear surface of the curved vibrator for reception. A contact damper provided with a high-density receiving damper made of a metal having a high specific gravity, and a receiving wedge provided on the side on which the test body is installed and in contact with the receiving curved vibrator. is there.

[Action]

In this invention, since the curved vibrator is curved along the shield plate so as to have a convex shape with respect to the side on which the test body is installed, the beam emitted from the vibrator propagates through the test body while expanding. . Further, since a high-density receiving damper made of metal having a high specific gravity is provided in contact with the back surface of the curved vibrator, free vibration of the vibrator is rapidly suppressed, and the vibration wave number is shortened. Furthermore, the combination of a curved oscillator and a damper reduces the change in sound pressure distribution within a wide effective beam.

〔Example〕

FIG. 1 (a) is a sectional view and a flaw detection waveform diagram of a two-divided vertical probe showing an embodiment of the present invention, and FIG. 1 (b) is a perspective view of the two-divided vertical probe.

FIG. 2 is a diagram showing the beam width characteristic, the sound pressure distribution within the beam width, and the arrangement of the probes of the two-part split type vertical probe according to the present invention.

In the figure, (1 ') is a curved surface oscillator for transmission, (2')
Is a curved surface oscillator for reception, (3 ') is a transmission wedge having a convex lens-shaped curved surface, (4') is a reception wedge having a convex lens-shaped curved surface, (5) is an acoustic shield plate, (7) ) Is a specimen, (8) is a defect near the surface, (9) is a defect near the bottom, (10) is an ultrasonic beam for detecting a defect (8) near the surface, and (11) is near the bottom. An ultrasonic beam for detecting the defect (9), (12'a) to (12'c) are two-divided vertical probes according to the present invention, (13'a) to (13'c) are effective beam widths, (15) is a high-density damper containing metal powder such as tungsten, (16 ') is approximately 15mm surface
Sound pressure distribution within effective beam width (13'a), (17 ')
Is the sound pressure distribution within the effective beam width (13'a) about 40 mm below the surface, (18 ') is the sound pressure distribution within the effective beam width (13'a) about 60 mm below the surface, and T is the transmission pulse , S is a surface echo, F ₁ is a reflection echo from a defect (8) near the surface, F ₂ is a reflection echo from a defect (9) close to the bottom surface, B
Is the bottom echo and R is the radii of curvature of the wedges (3 ') and (4') and the curved oscillators (1 ') and (2').

In the two-division type vertical probe configured as described above, ultrasonic beams (10), (11) from the curved surface transducer (1 ') for transmission to the curved surface transducer (2') for reception are transmitted. ) Is the same as in the case of the conventional two-division type vertical probe, but a damper made by press molding metal powder with high specific gravity on the back side of the curved vibrators (1 '), (2'). Since the material (15) is provided, the number of vibration waves of the curved surface vibrators (1 ') and (2') is reduced and the distance resolution is improved. As a result, the width of each reflected echo becomes narrower on the flaw detection waveform,
In particular, the separation of the reflected echo F ₂ from the defect (9) close to the bottom surface and the bottom echo B is complete.

Also, the ultrasonic beam emitted from the curved vibrator (1 ') propagates while expanding in the test body (7),
At this time, the effective beam width (13'a) to (13'c) can be set to a value approximately equal to or longer than the dimension in the longitudinal direction of the transducer even in the far field. , The tamper (15) effect makes the vibration wave number shorter, so wave interference is less likely to occur, resulting in a wider effective beam width (1
3'a) Sound pressure distribution at each depth (16 ') (1
It is possible to reduce changes in 7 ') and 18'.

Here, the curved oscillators (1 '), (2') and the damper (1
The effects of combining 5) and 5 will be described below.

FIG. 5 (a) is a concavo-convex (Δy) in the beam pattern at each depth distance of the flat plate vibrator, the flat plate vibrator + damper, the convex lens-shaped curved surface vibrator, the convex lens-shaped curved surface vibrator + damper, and the beam width. (W) and the distance resolution in the vicinity of the bottom surface are shown, and FIG. 5 (b) shows a performance comparison of ~ in FIG. 5 (a). 5 to (a) and (b) in FIG. 5 correspond to each other, and ○ in FIG. 5 (b) indicates that the performance (characteristic) is good, and x indicates that the performance (characteristic) is good. It's bad.

As is clear from the comparison of the above-described two-division type vertical probe, the convex lens-shaped curved surface vibrator has a large effect in expanding the beam width, and the damper has a large effect in improving the distance resolution. is there. However, the unevenness (Δy) in the beam pattern
Although only a damper can reduce the noise, the combination of a curved vibrator and a damper is the most effective. The reason is as follows.

That is, the unevenness in the beam pattern is the shortest distance l ₁ to the reflection source and the distance l ₂ reached from the edge of the vibrator when the positions of the reflection source and the vibrator are relatively changed in the length direction of the vibrator. This occurs because the ultrasonic waves interfere with each other.

In FIG. 6 (a), the waveforms of A and B interfere with each other in the same phase and A
It shows an example in which vibration increases with + B, but conversely A
-B may cause interference, and in this case, the vibration becomes small.

This is a phenomenon that occurs because the amplitude of the waveforms of A and B does not differ much because the vibrator is a plane.

As is clear from FIG. 6A, this interference can be reduced by adding a damper to the rear surface of the vibrator to reduce the vibration wave numbers of A and B, but the damper alone is not sufficient.

On the other hand, in the curved vibrator, the wave B propagating in l ₂ has a weak amplitude because the original ultrasonic wave emission direction is different from that of the flat vibrator in the curved vibrator. Therefore B wave is A
The impact on the waves is reduced.

This interference is still insufficient only with a curved oscillator without a damper, and a sufficient effect will be exhibited only by combining the curved oscillator and the damper.

As described above, the present invention is shown in FIG.
As shown in (b), a two-division type that simultaneously satisfies a wide beam width from a short distance to a long distance, reduces unevenness in the beam width pattern, and improves distance resolution near the bottom surface. A vertical probe can be provided, and in particular, a necessary condition for achieving reduction of unevenness in the beam width pattern is to combine both the curved surface vibrator and the damper at the same time.

Therefore, according to the present invention, by combining the curved surface vibrator and the damper, as shown in FIGS.

〔The invention's effect〕

In the two-part vertical probe according to the present invention, the curved vibrator is curved along the shield plate so as to have a convex shape with respect to the side on which the test body is installed. Beam propagates through the specimen while expanding,
Can secure a wide range of effective beams from short range to long range. 2
It is possible to efficiently arrange the split type vertical probe, and it is possible to inspect a wide range with the minimum required quantity.
A great improvement effect can be obtained both economically and in inspection efficiency.
In addition, since a high-density receiving damper made of metal with a high specific gravity is in contact with the back surface of the curved vibrator, free vibration of the vibrator is suddenly suppressed and the vibration wave number is shortened. As a result, even a defect close to the bottom surface can be sufficiently separated from the bottom surface echo, and it is possible to significantly improve the reliability of inspection because the number of missing defects is significantly reduced. Furthermore, by combining such a curved surface vibrator and a damper, it is possible to reduce the change in the sound pressure distribution within a wide effective beam, so that the reproducibility of defect detectability can be greatly improved.

[Brief description of drawings]

FIG. 1 (a) is a sectional view and flaw detection waveform diagram of a two-part split vertical probe according to the present invention, FIG. 1 (b) is a perspective view of the two-part split vertical probe, and FIG. FIG. 3 is a diagram showing the beam width characteristics of the two-segment vertical probe and the arrangement of the probes, FIG. 3 is a sectional view and a flaw detection waveform diagram of the conventional two-segment vertical probe, and FIG. FIG. 5 (a), FIG. 5 (b) and FIG. 6 (a) showing the beam width characteristics of the vertical probe and the arrangement of the probes.
(B) is a figure for demonstrating the effect of this invention. In the figure, (1) is a flat plate oscillator for transmission, (2) is a flat plate oscillator for reception, (1 ') is a curved surface oscillator for transmission,
(2 ') is a curved transducer for reception, (3) and (4) are wedges,
(3 '), (4') are convex lens-shaped curved surface wedges, (15)
Are dampers, (13a) to (13c) are effective beam widths by the conventional probe, (13'a) to (13'c) are effective beam widths by the probe of the present invention, and (14a) to (14c). ) Is an undetected area, and (15) is a damper. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A two-part vertical probe which is divided into a transmitting side and a receiving side by a shield plate and detects a defect in a test body, wherein the transmitting side has a convex shape with respect to a side on which the test body is installed. A curved curved surface for transmission that is curved along the shield plate so that the curved curved surface for transmission is provided in contact with the back surface of the curved curved surface for transmission, and a high-density transmitting damper made of metal having a high specific gravity. A shield for contacting with a curved surface oscillator for transmission, the wedge being provided on the side on which the test body is installed, and the receiving side having a convex shape with respect to the side on which the test body is installed. A curved receiver for reception curved along a plate, a high-density receiving damper made of metal having a high specific gravity and provided in contact with the back surface of the curved vibrator for reception, and the curved receiver for reception. Contacted and provided on the side where the test piece is installed 2 segmented vertical probe is characterized in that a credit wedge.