JP5909802B2 - Ultrasonic shear wave probe - Google Patents

Description

  The present invention relates to a probe that transmits ultrasonic waves to a test body and receives ultrasonic waves that propagate through the test body, and more particularly, an ultrasonic shear wave probe that transmits and receives transverse ultrasonic waves. It is about.

  In recent years, aging of structures has become a problem, and appropriate maintenance is required. Appropriate inspection is required to maintain and manage these aging structures. In particular, in the inspection of parts that cannot be visually confirmed, there is a great expectation for nondestructive inspection using ultrasonic waves, so-called ultrasonic flaw detection. In ultrasonic flaw detection, signals are transmitted and received using a probe, and the efficiency and stability are required.

  Ultrasonic flaw detection may be performed using transverse waves. In order to propagate a transverse wave perpendicular to the test body, a vertical transverse wave probe is used (for example, see Non-Patent Document 1).

  First, the configuration and operation of a conventional vertical shear wave probe will be described with reference to FIGS. FIG. 6 is a configuration diagram of a conventional vertical shear wave probe. The conventional vertical shear wave probe 100 shown in FIG. 6 includes a transducer 1, a protection plate 2, a damper 3, and a case 4. In Non-Patent Document 1, the “protective film 2” is used.

  The vertical transverse wave probe 100 having such a configuration propagates transverse waves through the contact medium 30 to the test body 20 to be inspected by ultrasonic flaw detection.

  As shown in FIG. 6, there are a protection plate 2 and a damper 3 on both sides of the vibrator 1. There is also a type of vertical shear wave probe without the damper 3. There is also a type in which the protective plate 2 is used as a matching layer in order to improve the transmission efficiency of ultrasonic waves to the test body 20. FIG. 7 is a diagram for explaining changes in the pressing force with respect to the elapsed time, the compressive stress applied to the protective plate, and the contact strength between the protective plate and the specimen in the conventional vertical shear wave probe.

  Next, the operation of the conventional vertical shear wave probe will be described. Here, a case where the probe 100 is handled by a human hand without using a special jig will be described as an example. When an electric signal from the flaw detector is applied to the vibrator 1, the vibrator 1 vibrates. Here, since the probe 100 is a shear wave probe, as shown in FIG. 6, the upper surface and the lower surface of the vibrator 1 vibrate in opposite directions. As a result, shear stress is generated, and the transverse wave propagates to the protection plate 2 and the damper 3. The transverse wave propagated in the direction of the damper 3 is attenuated inside the damper 3.

  On the other hand, the transverse wave propagated in the direction of the protective plate 2 propagates into the test body 20 through the contact medium 30. Here, as shown in Non-Patent Document 1, it is necessary to use a contact medium for transverse waves as the contact medium 30. The shear wave contact medium is a liquid material having a high viscosity such as water tank in order to transmit shear stress into the test body 20. Even if ordinary water is used as the contact medium 30, the shear stress is not transmitted, so that the transverse wave does not propagate into the specimen 20. In FIG. 6, the propagation direction and the vibration direction of the transverse wave are indicated by arrows.

  Thus, in the vertical shear wave probe 100, the flawed liquid contact medium 30 such as a water tank is flaw-detected with being sandwiched between the protective plate 2 and the test body 20. However, since the contact medium 30 is a liquid substance even if it is simply sandwiched, the shear wave hardly propagates into the specimen 20. Therefore, in order to propagate the transverse wave efficiently, the contact state between the protective plate 2 and the test body 20 needs to be strengthened. In addition, making a contact state firm means the state near fixation by an adhesive agent.

  A simple method for strengthening the contact state between the protection plate 2 and the test body 20 is to press the probe 100 against the test body 20 with a predetermined force. FIG. 6 shows a state where the probe 100 is pressed against the test body 20 from above the case 4. When pressed with a certain force, the vertical stress applied to the protection plate 2 increases, and as a result, the contact state between the protection plate 2 and the test body 20 becomes strong, and a transverse wave propagates into the test body 20. The transverse wave propagated to the test body 20 is reflected on the bottom surface, and the bottom surface echo is received. If there is a flaw in the specimen 20, there will be an echo reflected and received by the flaw.

Japan Nondestructive Inspection Association, published by Nikkan Kogyo Shimbun, "New Nondestructive Inspection Handbook", pages 260-261, 1992

However, the prior art has the following problems.
The conventional vertical shear wave probe 100 has a problem that it takes time to stabilize these echoes. This problem will be described with reference to FIG. The origin of the horizontal axis in FIG. 7 is the time when the probe 100 is placed on the test body 20. The initial value of the pressing force is the weight of the probe 100.

  As shown in FIG. 7A, when the probe 100 is pressed against the test body 20, the pressing force increases with time, and is saturated at a certain value due to the operator's force. In addition, not only simply pressing, but a method of pressing the probe 100 while sliding is generally used. This is because by sliding the probe 100, the contact medium 30 becomes thin, which helps to strengthen the contact state.

  As shown in FIG. 7B, the compressive stress applied to the protective plate 2 rises when the probe 100 is pressed and then saturates. Since the conventional vertical shear wave probe 100 has a low saturation level of compressive stress, the contact strength between the protective plate 2 and the test body 20 suddenly increases even when the compressive stress applied to the protective plate 2 reaches a saturated level. Will not be strong. More specifically, as shown in FIG. 7C, it gradually increases during the time when the probe is pressed. Then, after several minutes to several tens of minutes, the contact strength becomes saturated at a certain level and becomes stable, and the echo becomes stable.

  As described above, it takes a time from several minutes to several tens of minutes to stabilize the echo with the conventional vertical shear wave probe. In addition, the work of pressing the probe 100 against the test body 20 while sliding the probe 100 has been a heavy burden for the workers on site.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a vertical shear wave probe that stabilizes echoes at an early stage and does not impose a burden on a worker on site. It is.

The vertical transverse wave probe according to the present invention is brought into contact with a test body, propagates the ultrasonic wave of the transverse wave driven by the electrical signal into the test body, and transmits the ultrasonic wave of the transverse wave propagated through the test body to the electrical signal. An ultrasonic shear wave probe that performs ultrasonic flaw detection on a test body by converting to a surface of the ultrasonic shear wave probe that is in contact with the test body is equipped with a protective plate, and the protection The plate has a protrusion having a shape that becomes a stress concentration point, and transmits and receives a transverse ultrasonic wave from the protrusion .

  According to the vertical shear wave probe according to the present invention, the vertical shear wave probe has a protrusion having a shape that becomes a stress concentration point on the surface that contacts the specimen, and the weight of the probe alone is larger than that of the conventional probe. By providing a configuration capable of easily generating a compressive stress, it is possible to obtain a vertical shear wave probe that stabilizes echoes early and does not impose a burden on a worker on site.

It is a block diagram of the vertical shear wave probe in Embodiment 1 of this invention. It is an enlarged view of the contact part of the protection board and test piece in Embodiment 1 of this invention. It is a figure for demonstrating the change of the pressing force with respect to elapsed time, the compressive stress, and the contact strength in Embodiment 1 of this invention. It is a figure in case there exists a processus | protrusion in the protection plate of the array probe in Embodiment 1 of this invention. It is a figure in case there exists a processus | protrusion in the protection plate of the array probe in Embodiment 1 of this invention. It is a block diagram of the conventional vertical shear wave probe. It is a figure for demonstrating the change of the pressing force with respect to the elapsed time in the conventional vertical shear wave probe, the compressive stress applied to a protective plate, and the contact strength of a protective plate and a test body.

  Hereinafter, preferred embodiments of the vertical shear wave probe of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a vertical shear wave probe according to Embodiment 1 of the present invention. A vertical shear wave probe 10 according to the first embodiment shown in FIG. 1 includes a vibrator 1, a protective plate 2, a damper 3, and a case 4. In addition, as will be described in detail later with reference to FIG.

  Then, the vertical transverse wave probe 10 propagates the transverse wave through the contact medium 30 to the test body 20 to be inspected by ultrasonic flaw detection.

  FIG. 2 is an enlarged view of a contact portion between protective plate 2 and test body 20 in Embodiment 1 of the present invention. Moreover, FIG. 3 is a figure for demonstrating the change of the pressing force with respect to the elapsed time, compressive stress, and contact strength in Embodiment 1 of this invention.

  First, the configuration of the probe 10 according to the first embodiment will be described with reference to FIGS. There are a protection plate 2 and a damper 3 on both sides of the vibrator 1. This configuration is the same as that of the conventional vertical shear wave probe 100 shown in FIG. 6, and the damper 3 may not be provided. The difference from the conventional vertical shear wave probe 100 is that the surface of the protective plate 2 that contacts the test body 20 is not flat but has a shape in which the protrusions 2a are arranged.

  Next, the operation of the probe 10 according to the first embodiment will be described. The case where the probe 10 is handled by a human hand without using a special jig as in the conventional case will be described as an example. Similar to the conventional vertical transverse wave probe 100, when an electrical signal from the flaw detector is applied to the vibrator 1, the vibrator 1 vibrates. Here, since the probe 10 according to the first embodiment is a transverse wave probe, the upper surface and the lower surface of the vibrator 1 vibrate in opposite directions as shown in FIG. As a result, shear stress is generated and propagates to the protection plate 2 and the damper 3 as a transverse wave. The transverse wave propagated in the direction of the damper 3 is attenuated inside the damper 3.

  On the other hand, the transverse wave propagated in the direction of the protective plate 2 propagates into the test body 20 through the contact medium 30. This is shown in FIG. In the present invention, since the surface of the protective plate 2 has a shape in which the protrusions 2a are arranged, the compressive stress is concentrated on the tip portion of the protrusion 2a. For this reason, even with the weight of the probe 10 alone, a large compressive stress is applied to the tip of the protrusion 2a. As a result, the contact state between the protective plate 2 and the test body 20 can be strengthened without pressing with such a large force.

  That is, the conventional vertical shear wave probe 100 is pressed against the test body 20 by “surface”, whereas the vertical shear wave probe 10 of the present invention is applied to the test body 20 by “point” or “line”. There is a technical feature in that compressive stress is concentrated by pressing.

  1 and 2 also show the propagation direction and the vibration direction of the transverse wave. The transverse wave propagated to the test body 20 is reflected on the bottom surface and a bottom surface echo is received. If there is a flaw in the specimen 20, there is an echo that is reflected by the flaw and received.

  The operation of stabilizing these echoes will be described with reference to FIG. The origin of the horizontal axis in FIG. 3 is the time when the probe 10 is placed on the test body 20. The initial value of the pressing force is the weight of the probe 10.

  In the probe 10 according to the first embodiment, since the protection plate 2 is provided with a protrusion 2a that is a stress concentration point, as shown in FIG. Will occur. Moreover, a large compressive stress can be obtained with a pressing force smaller than that of the conventional probe 100. And if a big compressive stress is obtained, as shown in FIG.3 (c), a contact state will become strong immediately. For this reason, it takes a few seconds for the echo to stabilize.

  In FIG. 2, the vibration direction of the transverse wave and the arrangement pitch direction of the protrusions 2 a are described as being parallel. This configuration is effective for a normal vertical shear wave probe, but is particularly effective for an array probe. The reason for this will be described with reference to FIGS. 4 and 5 are diagrams in the case where there is a protrusion on the protective plate of the array probe according to the first embodiment of the present invention, in which the vibrators 1a, 1b, and 1c are arranged. 4 and 5, the contact medium 30 is omitted.

  FIG. 4 shows the case where the vibration direction of the transverse wave (horizontal direction in the figure) by the vibrators 1a, 1b, and 1c is parallel to the arrangement pitch direction of the protrusions 2a (that is, the vibration direction of the transverse wave and each one-dimensional arrangement of the protrusions 2a FIG. 5 is a diagram in the case where the direction is perpendicular to the direction. As shown in FIG. 4, when the vibration direction of the transverse wave and the arrangement pitch direction of the protrusions 2 a are parallel, the situation is the same as in FIGS. 1 and 2, so that the echo is stabilized early for the reason described above.

  On the other hand, FIG. 5 is a diagram when the protection plate 2 of FIG. 4 is rotated by 90 degrees, and when the vibration direction of the transverse wave and the arrangement pitch direction of the protrusions 2a are not parallel but vertical (that is, the transverse wave) The vibration direction and the direction of each one-dimensional array of protrusions 2a are parallel to each other). In the state shown in FIG. 5, if there is a tip portion of the protrusion 2a immediately below the transducers 1a, 1b, and 1c, the echo is stabilized early for the reason described above.

  However, if there is no tip portion of the protrusion 2a immediately below the vibrators 1a, 1b, and 1c, the transverse wave propagating in the test body 20 is weak. As described above, when the vibration direction of the transverse wave and the arrangement pitch direction of the protrusions 2a are perpendicular, the transmission efficiency of the ultrasonic waves may be increased depending on the positional relationship between the vibrators 1a, 1b and 1c and the tip of the protrusion 2a. There is a possibility of becoming a bad probe. The vibration direction of the transverse wave and the arrangement pitch direction of the protrusions 2a are parallel (that is, as shown in FIG. 4, the vibration direction of the transverse wave and the direction of each one-dimensional arrangement of the protrusions 2a have a vertical relationship). Thus, it is possible to obtain a probe whose echo is stabilized early without deteriorating the efficiency.

  2, 4 and 5, the tip of the protrusion 2a has been pointed. However, the tip of the protrusion 2a may have a curvature. Furthermore, the protrusion 2a may be rectangular. It is a feature of the present invention that a stress concentration point is provided on the protective plate 2, and the shape of the protrusion 2a is not limited.

  Furthermore, in FIG. 2, FIG. 4, and FIG. 5, the arrangement of the protrusions 2a has been described as one-dimensional, but it may be a two-dimensional arrangement. Further, except for an array probe, it may be arranged at random. Providing stress concentration points on the protective plate 2 is a feature of the present invention and does not limit the method of arranging the protrusions.

  As described above, according to the first embodiment, by providing the stress concentration point on the protection plate of the vertical transverse wave probe, it is possible to obtain an effect that the time until the echo is stabilized is shortened. Furthermore, it is possible to eliminate the need to strongly press the probe while sliding it, and it is possible to obtain the effect of greatly reducing the burden on the worker on site.

  DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c Vibrator, 2 Protection board, 2a Protrusion (protrusion part), 3 damper, 4 case, 10 vertical transverse wave probe (probe), 20 test body, 30 contact medium.

Claims (3)

The test is performed by contacting the test object, causing the ultrasonic wave of the transverse wave driven by the electric signal to propagate through the test object, and converting the ultrasonic wave of the transverse wave propagated through the test object into an electric signal. An ultrasonic shear wave probe for ultrasonic testing of the body,
Wherein the surface in contact with the specimen of the ultrasonic transverse wave probe, the protection plate is equipped, the protective plate has a plurality of projections of the shape which is the stress concentration point, the protrusion Ultrasonic shear wave probe that transmits and receives shear wave ultrasonic waves from the head. The ultrasonic shear wave probe according to claim 1,
The projection is an ultrasonic transverse wave probe formed as a one-dimensional or two-dimensional array. The ultrasonic shear wave probe according to claim 1,
The ultrasonic shear wave probe is an array probe;
The ultrasonic transverse wave probe is formed such that the protrusions are formed as a plurality of one-dimensional arrays, and the direction of each array has a direction perpendicular to the vibration direction of the transverse waves.

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