JP4483594B2 - Ultrasonic flaw detector - Google Patents

Description

  The present invention relates to an ultrasonic flaw detector that inspects a joint between a solid and a solid nondestructively. In particular, the present invention relates to an ultrasonic flaw detection apparatus that identifies and detects flaws that exist near the surface of a specimen and flaws that are inside the specimen.

  As a method for realizing this type of conventional ultrasonic flaw detector, for example, New Nondestructive Inspection Handbook, edited by Japan Nondestructive Inspection Association, pages 310 to 311 (hereinafter referred to as Document A) It is described in. Document A shows a method (surface wave method) in which flaws existing on the surface of a specimen are detected using surface waves. In the surface wave method, a surface wave is propagated to a specimen using a surface wave probe having an incident angle slightly larger than the critical angle with respect to a refraction transverse wave, and when there is a flaw on the surface, the surface wave is reflected by the flaw, By receiving the reflected surface wave as an echo, the vicinity of the surface of the specimen is detected. The “lateral wave” referred to here is not an SH wave but an SV wave. Hereinafter, all transverse waves not mentioned as SH waves will be explained as SV waves.

  Further, a method for detecting a flaw near the surface of the specimen is also disclosed in JP-A-9-80031. Japanese Patent Application Laid-Open No. 9-80031 discloses a method of inspecting an unwelded portion or a weld defect existing near the surface of a specimen using a surface SH wave probe. The normal surface SH wave probe sets the incident angle so that the refraction angle is 90 °, but the method disclosed in Japanese Patent Laid-Open No. 9-80031 is incident so that the refraction angle becomes 90 ° or more. It is characterized by setting a corner. With such an incident angle, it is said that a welding defect on the upper side (side where the probe exists) from the surface of the specimen can be detected.

  The above prior art shows a method of detecting without missing a surface and a flaw existing in the vicinity of the surface. However, there are cases where it is better not to detect flaws that hardly affect the strength of the structure, and there are also structures that do not want to detect such flaws. For example, there is no problem even if there is a certain amount of blowholes on the upper side of the specimen surface such as the upper part of the weld (the side where the probe exists) at the weld, but the root crack extending from the surface to the inside of the specimen is not There is a case where it is desired to detect without overlooking. When a structure in which these flaws are mixed is detected by the surface wave method shown in Document A, surface waves are scattered by blowholes and root cracks, so that echoes from both are received without discrimination. Echoes are received even if there are only blowholes and no root cracks. Since it is difficult to identify these echoes, even a healthy part where only blowholes exist is judged as “flawed” and may be overdetected. Further, since the method disclosed in Japanese Patent Laid-Open No. 9-80031 is a method of detecting a flaw above the surface of the specimen, there is a possibility of overdetection as in the surface wave method.

JP-A-9-80031 New Nondestructive Inspection Handbook, Japan Nondestructive Inspection Association, pages 310 to 311

  The present invention has been made to solve such a problem, and identifies and inspects an echo from a flaw near the surface of the test specimen and an echo from a flaw extending from the test specimen surface to the inside of the test specimen. An ultrasonic flaw detector that improves the accuracy of the results is obtained.

  In addition, when a steel weld is assumed as an inspection target, there are various forms of welding, and particularly in a complex joint, the accessible surface of the probe may be limited. The present invention is applicable to the case where the surface accessible to the probe is limited, i.e., the surface where the flaw is generated can be accessed by the probe and the flaw can be detected only from one side. A flaw detector is obtained.

In the ultrasonic flaw detector according to the present invention, an ultrasonic wave that is driven by an electric signal and transmits an ultrasonic wave into a test body, and receives an echo of the ultrasonic wave propagated through the test body and outputs the ultrasonic signal as an electric signal. Transmission / reception that transmits the electrical signal that drives the ultrasonic probe, the sound absorbing material that absorbs the ultrasonic wave, and the ultrasonic probe, and that receives the electrical signal output from the ultrasonic probe And a control device for controlling the presence or absence of installation of the sound absorbing material on a predetermined surface of the test body and controlling flaw detection in two states of whether or not the sound absorbing material is installed. The acoustic probe transmits a surface wave propagating in the vicinity of the surface of the specimen and a transverse wave propagating inside the specimen as the ultrasonic wave, and the echo of the surface wave and the echo of the transverse wave are transmitted as the ultrasonic wave. Received as an echo of a sound wave, A shear wave angle probe outputs Te, the sound absorbing material, controlled by being installed in a predetermined surface of the test body of the control device is intended to absorb the surface wave.

In the ultrasonic flaw detector according to the present invention, the surface wave and the transverse wave are propagated in the test body using the transverse wave oblique angle probe having a large refraction angle, and the state of the sound absorbing material is switched and inspected by the control device. It is possible to eliminate the detection of flaws that have little effect on the strength of the structure, and to detect flaws and echoes of cracks with high accuracy and to apply them to any detection, thereby improving the accuracy of inspection results. .

Embodiment 1 FIG.
FIG. 1 is a configuration explanatory view showing the configuration of an ultrasonic flaw detector according to Embodiment 1 of the present invention. FIG. 2 is an explanatory diagram for explaining a propagation path of an echo received using the ultrasonic flaw detector shown in FIG. FIG. 3 is a schematic diagram for explaining a flaw detection figure obtained when a flaw detection test is performed using the ultrasonic flaw detection apparatus shown in FIG.

  First, the configuration of the ultrasonic flaw detector shown in FIG. 1 will be described. In FIG. 1, 1 is a flaw detector, 2 is a transverse wave oblique angle probe, 3 is a base material, and 4 is a welded portion. A specimen including the base material 3 and the welded portion 4 is a test body. Reference numeral 5 denotes a crack generated from the surface of the test body and from the boundary between the base material 3 and the welded portion 4. 6 is a flaw in the weld and above the specimen surface. 7 is a sound absorbing material. The flaw detector 1 has a function of performing flaw detection by transmitting and receiving electrical signals to the transverse wave oblique angle probe 2. The crack 5 is a root crack that is considered to have a great influence on the strength of the welded portion. Further, the flaw 6 is a small blowhole or the like that is considered to have little influence on the strength of the welded portion. Note that the present invention does not depend on the type of flaws. The purpose is to identify and detect flaws on the upper side and lower side of the specimen surface, and the type of the flaws may not be blowholes or cracks.

  Next, the operation of the ultrasonic flaw detector shown in FIG. 1 will be described. An ultrasonic wave is generated from the transverse wave oblique angle probe 2 driven by the electric signal output as a transmission signal from the flaw detector 1. The refraction angle of the transverse wave oblique angle probe 2 is set to be large in order to detect a flaw extending inward from the surface of the specimen, and is set to about 85 ° as an example. However, the present invention is not limited to this, and the maximum value of the refraction angle is 90 °, and any angle that propagates not only the transverse wave but also the surface wave at an angle that can be used for inspection may be used. Due to the ultrasonic wave transmitted from the transverse wave oblique angle probe 2, not only the transverse wave propagates inside the specimen, but also the surface wave propagates along the surface of the specimen.

  FIG. 2 shows a propagation path of the surface wave and the transverse wave that enter the specimen from the transverse wave oblique angle probe 2. As shown in the figure, the surface wave propagates along the surface of the base material 3. Thereafter, when the sound absorbing material 7 is reached, the sound absorbing material 7 is absorbed and thus attenuates. The surface wave attenuated by the sound absorbing material 7 propagates to the surplus portion of the weld 4 and is scattered by the flaw 6. After being scattered by the flaw 6, it follows the reverse path and is received as an echo by the transverse wave oblique angle probe 2. The sound absorbing material 7 also attenuates when following the reverse path.

  On the other hand, the transverse wave propagating in the test body propagates through the base material 3, then propagates through the welded portion 4, and reaches the crack 5. After being scattered by the crack 5, it is received by the transverse wave oblique probe 2 along the reverse path. That is, the sound absorbing material 7 is not affected.

FIG. 3 shows a flaw detection figure in which echoes received by the transverse wave oblique angle probe 2 are displayed on a display provided in the flaw detector 1. Since the surface wave is attenuated by the sound absorbing material 7, the height of the echo due to the scratch 6 is small. On the other hand, since the transverse wave is not affected by the sound absorbing material 7, the echo caused by the crack 5 is large. Therefore, even if the test specimen is such that the crack 5 and the crack 6 coexist and the echo from the scratch 6 becomes a disturbing echo, the sound absorbing material 7 reduces the surface wave to reduce the crack 5. Detection accuracy is improved.
Here, the display device may be a device installed on the flaw detector 1 or a display device such as an oscilloscope connected to the flaw detector 1 or may print out a flaw detection figure.

  The material of the sound absorbing material 7 is not particularly defined as long as it can absorb surface waves. A contact medium such as glycerin or machine oil used in the flaw detection test may be used, or water may be used. In addition, instead of using a contact medium or water as the sound absorbing material 7, the same effect as that of installing the sound absorbing material 7 can be obtained when the measurer contacts a predetermined position of the test body.

  In FIG. 1, the butt weld is an inspection object, but the present invention is not applied only to the butt weld, and can be applied to, for example, inspection of various structures such as a T joint weld. That is, the present invention can be applied to all test objects in which the echoes from the flaws on the upper side of the test body surface are reduced and the inspection is performed by the echoes from the flaws on the lower side of the test body surface.

As described above, in the ultrasonic flaw detector according to the present invention, the surface wave and the transverse wave are propagated in the test body using the transverse wave oblique angle probe 2 having a large refraction angle, and the sound absorbing material 7 is used to create a flaw. Since only the echoes from 6 are attenuated and reduced, the detection accuracy of the crack 5 existing near the surface can be improved.
Also, by using the shear wave oblique angle probe 2, the ultrasonic flaw detection can be applied to the case where only the surface on which the flaw 6 is generated can be accessed by the probe and the flaw can be detected only from one side. Get the equipment.

Embodiment 2. FIG.
FIG. 4 is an explanatory diagram showing the configuration of the ultrasonic flaw detector according to Embodiment 2 of the present invention. FIG. 5 is a schematic diagram for explaining a flaw detection figure obtained when a flaw detection test is performed using the ultrasonic flaw detection apparatus shown in FIG.

  First, the configuration of the ultrasonic flaw detector shown in FIG. 4 will be described. The ultrasonic flaw detection apparatus shown in FIG. 4 is provided with a control device 8 in the ultrasonic flaw detection apparatus shown in FIG. The control device 8 is a device that performs control related to the installation of the sound absorbing material 7 on the surface of the test body and controls the flaw detection test for each state of the presence or absence of the sound absorbing material 7. Others are the same as FIG. 1 of Embodiment 1, and description is abbreviate | omitted.

  Next, the operation of the ultrasonic flaw detector shown in FIG. 4 will be described. Here, the case where the state without the sound absorbing material 7 is performed first and the state with the sound absorbing material 7 is performed later will be described. The order may be reversed. First, the sound absorbing material 7 is removed from the surface of the test body by the control device 8. Then, similarly to the first embodiment, ultrasonic waves generated by the transverse wave oblique probe 2 driven by the transmission signal from the flaw detector 1 are transmitted into the specimen. The refraction angle of the transverse wave oblique angle probe 2 is set large in order to detect the flaw 5 extending inward from the surface of the test body, and is set to about 85 ° as an example. Due to the ultrasonic wave transmitted from such a transverse wave oblique angle probe 2, not only the transverse wave propagates inside the specimen, but also the surface wave propagates along the surface of the specimen.

  Here, since the sound absorbing material 7 is removed by the control device 8, the surface acoustic wave is not attenuated by the sound absorbing material 7, propagates to the extra portion of the weld 4, and is scattered by the flaw 6. After being scattered by the flaw 6, it follows the reverse path and is received as an echo by the transverse wave oblique angle probe 2. It should be noted that there is no attenuation by the sound absorbing material 7 when following the reverse path.

  FIG. 5 shows a flaw detection figure in which echoes received by the transverse wave oblique angle probe 2 are displayed on a display provided in the flaw detector 1. Since the sound absorbing material 7 is removed from the test body, the surface wave is not attenuated. As a result, the level of the echo due to the scratch 6 as shown in FIG. It becomes bigger than the case of. On the other hand, the transverse wave that propagates inside the test specimen propagates through the base material 3, then propagates through the welded portion 4, and reaches the crack 5. Further, after being scattered by the crack 5, the sound wave is received by the transverse wave oblique probe 2 along the reverse path, so that it is not affected by the sound absorbing material 7. Therefore, it is received at a high level as in the case of the first embodiment shown in FIG.

  Further, when the sound absorbing material 7 is placed on a predetermined flaw detection surface of the test body under the control of the control device 8, the situation is the same as in the first embodiment, and therefore the propagation of the surface wave and the transverse wave is in the first embodiment. It becomes the same as the explanation in. The flaw detection figure is the same as that shown in FIG.

  As described above, the flaw detection pattern shown in FIG. 3 or FIG. 5 is obtained by controlling the presence or absence of the sound absorbing material 7 by the control device 8 and conducting a flaw detection test for each state. Comparing FIG. 5 and FIG. 3, what changes in the flaw detection figure is an echo from the flaw 6, and what does not change is an echo from the crack 5, so that the echo of the flaw 6 and the crack 5 is identified with high accuracy. It becomes possible. Therefore, the present invention can be applied to the case where only the crack 5 is to be detected, and can also be applied to the case where only the flaw 6 is to be detected.

  The control device 8 need not be a so-called mechanical device, and the measurer may control the presence or absence of the sound absorbing material 7. Further, the material of the sound absorbing material 7 is not particularly defined as long as it can absorb surface waves. A contact medium such as glycerin or machine oil used in the flaw detection test may be used, or water may be used. Furthermore, instead of using a contact medium or water as the sound absorbing material 7, the same effect as when the sound absorbing material 7 is installed can be obtained when the measurer contacts a predetermined position of the test body.

As described above, in the ultrasonic flaw detector according to the present invention, the surface wave and the transverse wave are propagated in the test body by using the transverse wave oblique angle probe 2 having a large refraction angle, and the control device 8 causes the sound absorbing material 7 to be transmitted. Since inspection is performed by switching the presence / absence state, detection of flaws 6 that hardly affect the strength of the structure can be eliminated, and echoes of flaws 6 and cracks 5 can be identified with high accuracy and applied to any detection. It is possible to improve the accuracy of the inspection result.
Also, by using the shear wave oblique angle probe 2, the ultrasonic flaw detection can be applied to the case where only the surface on which the flaw 6 is generated can be accessed by the probe and the flaw can be detected only from one side. Get the equipment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration explanatory view showing a configuration of an ultrasonic flaw detector according to Embodiment 1 of the present invention. It is explanatory drawing for demonstrating the propagation path of the echo received using the ultrasonic flaw detector shown in FIG. It is a schematic diagram for demonstrating the flaw detection figure obtained when a flaw detection test is performed using the ultrasonic flaw detection apparatus shown in FIG. It is a structure explanatory drawing which shows the structure of the ultrasonic flaw detector which concerns on Embodiment 2 of this invention. It is a schematic diagram for demonstrating the flaw detection figure obtained when a flaw detection test is performed using the ultrasonic flaw detection apparatus shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Flaw detector, 2 Shear wave bevel probe, 3 Base material, 4 Welded part, 5 Crack, 6 Scratch, 7 Sound absorption material, 8 Control apparatus.

Claims (2)

An ultrasonic probe that is driven by an electrical signal, transmits an ultrasonic wave into the test body, and receives an echo of the ultrasonic wave that has propagated through the test body and outputs it as an electrical signal;
A sound-absorbing material that absorbs the ultrasonic waves;
A transmitter / receiver for transmitting the electric signal for driving the ultrasonic probe and receiving the electric signal output from the ultrasonic probe;
A control device for controlling the presence or absence of installation of the sound absorbing material on a predetermined surface of the test body, and for controlling flaw detection in two states of whether or not the sound absorbing material is installed;
With
The ultrasonic probe transmits a surface wave propagating in the vicinity of the surface of the specimen and a transverse wave propagating in the specimen as the ultrasonic wave, and the echo of the surface wave and the echo of the transverse wave are transmitted. It is a transverse wave oblique angle probe that receives the ultrasonic echo and outputs it as an electrical signal,
The ultrasonic flaw detector is characterized in that the sound absorbing material is installed on a predetermined surface of the specimen under the control of the control device and absorbs the surface wave. 2. The ultrasonic flaw detector according to claim 1, wherein the transceiver includes display means or recording means for displaying an echo of the ultrasonic wave based on the received electrical signal from the transverse wave oblique angle probe. .

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