JP2012112851A - Ultrasonic inspection device and ultrasonic inspection method - Google Patents

Abstract

An object of the present invention is to accurately inspect an end portion of an inspection object by suppressing a diffracted wave that reaches an ultrasonic receiving device by bypassing the inspection object.
A transmission side ultrasonic shielding cap 14 surrounds the entire circumference of an ultrasonic transmission surface 12 and protrudes from the periphery of the ultrasonic transmission surface 12 to a surface end 32a of a steel plate 32 over the entire circumference. Is provided. The reception-side ultrasonic shielding cap 24 surrounds the entire circumference of the ultrasonic reception surface 22, and is provided so as to protrude from the periphery of the ultrasonic reception surface 22 to the back surface end 34 b of the steel plate 34 over the entire circumference. Yes. With the transmission side ultrasonic shielding cap 14 and the reception side ultrasonic shielding cap 24, the ultrasonic wave transmitted from the ultrasonic transmission surface 12 bypasses the inspection object 30 and reaches the ultrasonic reception surface 22 as a diffracted wave. Can be suppressed.
[Selection] Figure 1

Description

  The present invention relates to an ultrasonic inspection apparatus and an ultrasonic inspection method for inspecting an inspection object using ultrasonic waves.

  As means for performing non-destructive evaluation of materials, techniques using radiation, electromagnetics, ultrasonic waves, and the like are used according to applications. Among them, ultrasonic waves are widely used as a method that can be easily introduced at production sites and the like because they have little influence on the human body and can inspect materials.

  However, in order to receive ultrasonic waves from inside the solid material and to receive ultrasonic waves from the inside of the solid material, conventionally, a coupling agent such as water or gel must be used between the material and the ultrasonic sensor. It was. Therefore, even for inspections on the production line, it is necessary to immerse the entire inspection object in water (water immersion method) or to spray water between the ultrasonic sensor and the inspection object only (partial immersion method). Yes, its application was limited to steel lines.

  In recent years, an aerial ultrasonic sensor has been developed that can receive high-accuracy ultrasonic waves in the air, enter the material, propagate through the material, and then receive the ultrasonic waves leaking from the material with high sensitivity (see below for the aerial ultrasonic method). Patent References 1 to 6). In the air, the higher the frequency, the higher the attenuation. Therefore, the frequency band is limited to a frequency band lower than the frequency band (1 MHz to 100 MHz) that can be used by the water immersion method, but it is desirable to use a frequency band as high as possible in order to improve inspection resolution. The frequency band of the developed aerial ultrasonic sensor is about 50 kHz to 1 MHz. Although high spatial resolution as high as the water immersion method cannot be expected, it is possible to inspect without contact, so it can be expected to be applied to 100% inspection in the line.

JP 2008-128965 A JP 2002-195987 A Japanese Patent No. 4120969 JP 2006-138818 A JP 2009-150692 A JP 2010-25817 A JP-A-8-21892 Japanese Patent No. 3480311 Japanese Patent No. 3036632 JP-A-8-313502 JP-A-64-73250

  As a technique for inspecting an inspection object using ultrasonic waves, for example, as in Patent Document 1, ultrasonic waves are transmitted from an ultrasonic transmission device arranged on the surface side of the inspection object, and transmitted through the inspection object. There is a transmission method in which the ultrasonic wave is received by an ultrasonic receiving device arranged on the back side of the inspection object. However, when the end of the inspection object is inspected by the transmission method, the ultrasonic wave received by the ultrasonic receiver is only transmitted waves that pass through the inspection object and reach the ultrasonic receiver. There is also a diffracted wave that bypasses the inspection target and reaches the ultrasonic receiver. This diffracted wave is received by the ultrasonic receiving device at approximately the same time as the transmitted wave, and further, the closer the ultrasonic transmitting device and the ultrasonic receiving device are to the side surface of the inspection object, the higher the reception level at the ultrasonic receiving device. Easy to grow. In order to accurately inspect the end of the inspection object, it is necessary to accurately detect the amplitude of the transmitted wave that passes through the inspection object and reaches the ultrasonic receiver from the received signal at the ultrasonic receiver. For this purpose, it is desirable to suppress diffracted waves that reach the ultrasonic receiving device by bypassing the inspection object.

  An object of the present invention is to accurately inspect an end portion of an inspection object by suppressing a diffracted wave that reaches the ultrasonic receiving device by bypassing the inspection object.

  The ultrasonic inspection apparatus and ultrasonic inspection method according to the present invention employ the following means in order to achieve the above-described object.

  An ultrasonic inspection apparatus according to the present invention is an ultrasonic transmission surface that is disposed opposite to a surface end portion of an inspection object, and includes an ultrasonic transmission surface that transmits ultrasonic waves to the surface end portion of the inspection object. An ultrasonic wave receiving device and an ultrasonic wave receiving surface that is arranged to face the back surface end of the inspection object so as to face the ultrasonic wave transmission surface through the inspection object, and is transmitted from the ultrasonic transmission surface and inspected An ultrasonic receiving device including an ultrasonic receiving surface that receives an ultrasonic wave transmitted through the inside, wherein the ultrasonic transmitting device surrounds the entire circumference of the ultrasonic transmitting surface The through-holes that project from the circumference of the ultrasonic transmission surface to the edge of the surface of the object to be inspected over the entire circumference and transmit ultrasonic waves from the ultrasonic wave transmission surface to the surface of the object of inspection are transmitted through the ultrasonic wave. Transmission formed from the edge on the surface side to the edge on the surface side of the inspection object An ultrasonic shielding member, further comprising a transmission-side ultrasonic shielding member for suppressing the ultrasonic wave transmitted from the ultrasonic transmission surface from reaching the ultrasonic reception surface by bypassing the inspection object The gist.

  In one aspect of the present invention, the ultrasonic transmission surface has a concave curved surface shape in which a focal point is located in the inspection object, and the diameter of the through hole formed in the transmission-side ultrasonic shielding member is the surface side of the inspection object. It is preferable to be smaller than the ultrasonic transmission surface side.

  In one aspect of the present invention, it is preferable that the acoustic impedance of the transmission-side ultrasonic shielding member is smaller than the acoustic impedance of the inspection object.

  In one aspect of the present invention, the ultrasonic receiving device surrounds the entire circumference of the ultrasonic receiving surface, protrudes from the periphery of the ultrasonic receiving surface to the back surface end portion of the inspection object, and is inspected. A receiving-side ultrasonic shield in which a through-hole for propagating ultrasonic waves from the back end of the object to the ultrasonic receiving surface in the air is formed from the end on the ultrasonic receiving surface side to the end on the back side of the inspection object. Preferably, the apparatus further includes a reception-side ultrasonic shielding member for suppressing the ultrasonic wave transmitted from the ultrasonic transmission surface from reaching the ultrasonic reception surface by bypassing the inspection object. .

  In addition, an ultrasonic inspection apparatus according to the present invention is an ultrasonic transmission surface that is disposed opposite to a surface end portion of an inspection object, and includes an ultrasonic transmission surface that transmits ultrasonic waves to the surface end portion of the inspection object. An ultrasonic transmission device including an ultrasonic transmission surface disposed opposite to the back end portion of the inspection object so as to face the ultrasonic transmission surface via the inspection object, and transmitted from the ultrasonic transmission surface and inspected An ultrasonic receiving device including an ultrasonic receiving surface that receives ultrasonic waves transmitted through an object, wherein the ultrasonic receiving device extends around the entire circumference of the ultrasonic receiving surface. The through-holes that project from the periphery of the ultrasonic receiving surface to the back end of the object to be inspected over the entire circumference and propagate ultrasonic waves from the back end of the inspection object to the ultrasonic receiving surface in the air. It is formed from the end on the sound wave receiving surface side to the end on the back side of the inspection object. A reception-side ultrasonic shielding member, further including a reception-side ultrasonic shielding member for suppressing the ultrasonic wave transmitted from the ultrasonic transmission surface from reaching the ultrasonic reception surface by bypassing the inspection object This is the gist.

  In one aspect of the present invention, the ultrasonic receiving surface has a concave curved surface shape in which the focal point is located in the inspection object, and the diameter of the through hole formed in the reception-side ultrasonic shielding member is the back surface side of the inspection object. It is preferable to be smaller than the ultrasonic wave receiving surface side.

  In one aspect of the present invention, it is preferable that the acoustic impedance of the reception-side ultrasonic shielding member is smaller than the acoustic impedance of the inspection object.

  In one aspect of the present invention, the inspection object is such that the first plate-like member and the second plate-like member are bonded to each other through the adhesive layer at the end, and the ultrasonic transmission surface is the surface of the first plate-like member. The ultrasonic wave is transmitted to the adhesive layer through the first plate member, and the ultrasonic wave receiving surface is ultrasonically transmitted through the first plate member, the adhesive layer, and the second plate member. Receiving the ultrasonic wave transmitted from the ultrasonic transmission surface and transmitted through the first plate member, the adhesive layer, and the second plate member so as to face the rear surface end of the second plate member so as to face the surface. Is preferred.

  Further, the ultrasonic inspection method according to the present invention is an ultrasonic inspection method using the ultrasonic inspection apparatus according to the present invention, wherein the ultrasonic transmission position with respect to the inspection object is moved and scanned in two dimensions. Based on the amplitude of the ultrasonic wave corresponding to each ultrasonic wave transmission position received by the ultrasonic wave reception device and received by the ultrasonic wave reception device, transmitted from the ultrasonic wave transmission device and transmitted through the inspection object, The gist is to inspect the inspection object.

  According to the present invention, when the end of the inspection object is inspected, the ultrasonic wave transmitted from the ultrasonic transmission surface is prevented from bypassing the inspection object and reaching the ultrasonic reception surface as a diffracted wave. Therefore, the amplitude of the transmitted wave that passes through the inspection object and reaches the ultrasonic wave reception surface can be accurately detected from the reception signal on the ultrasonic wave reception surface. As a result, the end of the inspection object can be inspected with high accuracy.

1 is a diagram showing a schematic configuration of an ultrasonic inspection apparatus according to an embodiment of the present invention. 1 is a diagram showing a schematic configuration of an ultrasonic inspection apparatus according to an embodiment of the present invention. 1 is a diagram showing a schematic configuration of an ultrasonic inspection apparatus according to an embodiment of the present invention. It is a figure explaining the propagation path of the ultrasonic wave from an ultrasonic transmission surface to an ultrasonic reception surface. It is a figure explaining the measurement conditions of the ultrasonic wave for investigating the influence of a diffracted wave. It is a figure which shows the waveform of the ultrasonic signal received by the ultrasonic receiving surface when an ultrasonic transmission sensor and an ultrasonic receiving sensor are made to face each other on both sides of a steel plate. It is a figure which shows the other schematic structure of the ultrasonic inspection apparatus which concerns on embodiment of this invention. It is a figure which shows the other schematic structure of the ultrasonic inspection apparatus which concerns on embodiment of this invention. It is a figure which shows the waveform of the ultrasonic signal received by the ultrasonic receiving surface in the ultrasonic inspection apparatus which concerns on embodiment of this invention. It is a figure which shows the change of the amplitude of the ultrasonic signal received by the ultrasonic receiving surface when the central axis of an ultrasonic transmitting surface and an ultrasonic receiving surface is moved. It is a figure which shows an example of a test target object. It is a figure which shows the result of having imaged the amplitude distribution of the ultrasonic signal corresponding to each ultrasonic transmission position when there is no ultrasonic shielding cap. It is a figure which shows the result of having imaged the amplitude distribution of the ultrasonic signal corresponding to each ultrasonic transmission position when there exists an ultrasonic shielding cap. It is a flowchart explaining an example of the evaluation method of the adhesiveness by the contact bonding layer between steel plates using the ultrasonic inspection apparatus which concerns on embodiment of this invention. It is a figure which shows the other schematic structure of the ultrasonic inspection apparatus which concerns on embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  1 to 3 are diagrams illustrating a schematic configuration of an ultrasonic inspection apparatus according to an embodiment of the present invention. FIG. 1 illustrates a schematic configuration of the entire apparatus. FIGS. 2 and 3 illustrate an ultrasonic transmission sensor 10 and an ultrasonic reception. A schematic configuration of the sensor 20 is shown. The ultrasonic inspection apparatus according to the present embodiment includes an ultrasonic transmission sensor 10, an ultrasonic reception sensor 20, a scanning device 40, an ultrasonic signal supply unit 41, a signal processing unit 42, an image processing unit 44, A display device 46 and an inspection determination unit 48 are provided.

  The inspection object 30 is configured to include steel plates 32 and 34 that are plate-like members and an adhesive layer 36 for joining the steel plates 32 and 34 at the ends, and the back end portion 32b of the steel plate 32 and the steel plate 34. The surface end portion 34 a of the first and second surfaces are joined through an adhesive layer 36. A region where the adhesive layer 36 is not provided between the steel plates 32 and 34 is a gap. In the following description, as an application example of the inspection of the inspection object 30 using the ultrasonic inspection apparatus according to the present embodiment, a case where the adhesion by the adhesive layer 36 of the steel plates 32 and 34 is evaluated will be described.

  The ultrasonic transmission sensor 10 includes an ultrasonic transmission surface 12 disposed to face the surface end portion 32a of the inspection object 30 (steel plate 32) so as to face the adhesive layer 36 through the steel plate 32, and a transmission-side ultrasonic shielding cap. 14. The ultrasonic transmission surface 12 can be constituted by, for example, a piezoelectric element. An ultrasonic signal from the ultrasonic signal supply unit 41 is supplied to the ultrasonic transmission sensor 10. The ultrasonic transmission sensor 10 transmits an ultrasonic wave from the ultrasonic transmission surface 12 to the surface end portion 32 a of the steel plate 32 based on the ultrasonic signal supplied from the ultrasonic signal supply unit 41. The ultrasonic wave transmitted from the ultrasonic transmission surface 12 propagates in the air and enters the surface end portion 32a of the steel plate 32 as indicated by an arrow 61 in FIG. The ultrasonic wave incident on the surface end portion 32a of the steel plate 32 passes through the steel plate 32 and reaches the adhesive layer 36, and further passes through the adhesive layer 36 and the steel plate 34 for inspection as shown by the arrow 62 in FIG. It reaches the back side of the object 30 (steel plate 34). In the example illustrated in FIG. 1, the ultrasonic transmission sensor 10 is a focus sensor, and the ultrasonic transmission surface 12 has a concave curved surface shape in which the focal point 38 is located in the inspection object 30 (adhesive layer 36). The ultrasonic wave transmitted from the transmission surface 12 is focused on the focal point 38 (adhesive layer 36). The configuration of the transmission side ultrasonic shielding cap 14 will be described later.

  The ultrasonic receiving sensor 20 is disposed so as to face the back end 34b of the inspection object 30 (steel plate 34) so as to face the ultrasonic transmission surface 12 via the inspection object 30 (steel plate 32, adhesive layer 36, and steel plate 34). An ultrasonic receiving surface 22 and a receiving-side ultrasonic shielding cap 24 are configured. The ultrasonic receiving surface 22 can also be configured by, for example, a piezoelectric element. The ultrasonic wave that has reached the back side of the inspection object 30 (steel plate 34) propagates in the air and reaches the ultrasonic wave receiving surface 22 as indicated by an arrow 63 in FIG. The ultrasonic reception sensor 20 receives ultrasonic waves transmitted from the ultrasonic transmission surface 12 and transmitted through the inspection object 30 (the steel plate 32, the adhesive layer 36, and the steel plate 34) by the ultrasonic reception surface 22. In the example shown in FIG. 1, the ultrasonic reception sensor 20 is also a focus type sensor, and the ultrasonic reception surface 22 is also a concave curved surface shape in which the focal point 38 is located in the inspection object 30 (adhesive layer 36). The ultrasonic waves focused on are diffused and reach the entire ultrasonic receiving surface 22. The configuration of the reception-side ultrasonic shielding cap 24 will be described later.

  The scanning device 40 causes the ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20 (the ultrasonic transmission surface 12 and the ultrasonic reception surface 22) to move and scan two-dimensionally in parallel with the plate surface directions of the steel plates 32 and 34. Thereby, the focal point 38 of the ultrasonic transmission surface 12 and the ultrasonic reception surface 22 can be moved and scanned two-dimensionally in parallel with the plate surface direction of the steel plates 32 and 34 with respect to the inspection target object 30. The ultrasonic transmission position (adhesion evaluation position) with respect to 30 can be moved and scanned two-dimensionally in parallel with the plate surface direction of the steel plates 32 and 34. When evaluating the adhesion of the steel plates 32, 34 by the adhesive layer 36, ultrasonic waves are transmitted from the ultrasonic transmission device 10 while the scanning device 40 moves and scans the ultrasonic transmission position relative to the inspection object 30 in two dimensions. The ultrasonic wave reception device 20 receives the ultrasonic wave transmitted and transmitted through the inspection object 30. At that time, by using the ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20 as focus type sensors, the spatial resolution of the adhesion evaluation position with respect to the inspection object 30 can be improved.

  The signal processing unit 42 detects the amplitude of the ultrasonic signal corresponding to each ultrasonic transmission position (adhesion evaluation position) received by the ultrasonic reception sensor 20 (ultrasonic reception surface 22). The image processing unit 44 images the amplitude of the ultrasonic signal detected by the signal processing unit 42 in a two-dimensional plane in association with each ultrasonic transmission position, and causes the display device 46 to display the two-dimensional image. The inspection determination unit 48 evaluates the adhesion of the steel plates 32 and 34 by the adhesive layer 36 based on the amplitude of the ultrasonic signal corresponding to each ultrasonic transmission position detected by the signal processing unit 42. The object 30 is inspected. For example, when there is peeling at the interface between the steel plate 32 (or the steel plate 34) and the adhesive layer 36, the inspection object 30 (the steel plate 32, the adhesive layer 36, and the steel plate 34) is transmitted through compared with the case where there is no peeling. The level of the ultrasonic signal received by the ultrasonic receiving surface 22 decreases. Therefore, it is possible to evaluate the adhesion of the steel plates 32 and 34 by the adhesive layer 36 by examining the amplitude of the ultrasonic wave received by the ultrasonic wave receiving surface 22 and corresponding to each ultrasonic wave transmitting position.

  When evaluating the adhesion by the adhesive layer 36 at the ends of the steel plates 32 and 34, the ultrasonic wave is transmitted from the ultrasonic transmission surface 12 toward the surface end portion 32a of the steel plate 32, and from the back end portion 34b of the steel plate 34. Are received by the ultrasonic wave receiving surface 22. At that time, most of the ultrasonic energy transmitted from the ultrasonic transmission sensor 10 (focus type sensor) is focused toward the focal point 38 as shown by arrows 61 and 62 in FIG. As shown by an arrow 64 in FIG. 4, a diffracted wave propagates in the air in a direction spreading from the sensor, and as shown by arrows 65 and 66 in FIG. To do. As a result, the ultrasonic wave received by the ultrasonic wave receiving surface 22 is transmitted through the inspection object 30 (the steel plate 32, the adhesive layer 36, and the steel plate 34) as shown by arrows 61 to 63 in FIG. In addition to the transmitted wave reaching the sound wave receiving surface 22, in practice, as shown by arrows 64 to 66 in FIG. 4, the ultrasonic wave bypasses the inspection object 30 (the steel plate 32, the adhesive layer 36, and the steel plate 34). There is also a diffracted wave that reaches the receiving surface 22. This diffracted wave is received by the ultrasonic wave receiving surface 22 at substantially the same time as the transmitted wave. Further, the ultrasonic wave transmitting surface 12 and the ultrasonic wave receiving surface 22 are moved to the side surface of the inspection object 30 (the side surfaces 32c of the steel plates 32 and 34, 34c), the reception level at the ultrasonic wave receiving surface 22 tends to increase. In order to accurately evaluate the adhesion due to the adhesive layer 36 at the ends of the steel plates 32 and 34, the amplitude of the transmitted wave that passes through the inspection object 30 and reaches the ultrasonic receiving surface 22 is defined as the ultrasonic receiving surface 22. Therefore, it is desirable to suppress the diffracted wave that reaches the ultrasonic wave receiving surface 22 by bypassing the inspection object 30. In particular, when the inspection object 30 has a three-layer structure such as the steel plate 32, the adhesive layer 36, and the steel plate 34, the energy of the ultrasonic wave that passes through the region becomes very small. Even if a diffracted wave with a slight energy is mixed, the adhesion evaluation is greatly affected.

  As shown in FIG. 5, a single steel plate 33 (SPC 270, thickness 0.8 mm) is sandwiched as the inspection object 30, and the ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20 (however, on the transmission side) that are focus type sensors. When the ultrasonic shielding cap 14 and the receiving-side ultrasonic shielding cap 24 are not provided) at a distance of 40 mm perpendicular to the steel plate 33, the waveform of the ultrasonic signal received by the ultrasonic receiving surface 22 is as follows. As shown in FIG. When the distance L from the side surface (end surface) 33c of the steel plate 33 to the central axis of the ultrasonic wave transmitting surface 12 and the ultrasonic wave receiving surface 22 is 20 mm, as shown in the waveform at the bottom of FIG. It is possible to detect a transmitted wave that passes through the steel plate 33 from the reception signal at the ultrasonic wave receiving surface 22 without being substantially affected by the above. However, when the distance L from the side surface (end surface) 33c of the steel plate 33 is 5 mm, the influence of the diffracted wave is very large as shown in the waveform on FIG. 6, and the saturation voltage (2V) of the signal processing unit 42 is It is difficult to detect a transmitted wave passing through the steel plate 33 from the received signal at the ultrasonic wave receiving surface 22 because a voltage exceeding the voltage is measured.

  Therefore, in the present embodiment, in order to suppress the ultrasonic wave transmitted from the ultrasonic transmission surface 12 from bypassing the inspection object 30 and reaching the ultrasonic reception surface 22 as a diffracted wave, the transmission side ultrasonic shielding is performed. The cap 14 and the reception-side ultrasonic shielding cap 24 are provided on the ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20, respectively. Hereinafter, configuration examples of the transmission-side ultrasonic shielding cap 14 and the reception-side ultrasonic shielding cap 24 for shielding ultrasonic waves will be described.

  As shown in FIGS. 1 to 3, the transmission-side ultrasonic shielding cap 14 surrounds the entire circumference of the ultrasonic transmission surface 12, and the inspection object 30 (steel plate 32) is surrounded from the periphery of the ultrasonic transmission surface 12. A through-hole 14c for propagating ultrasonic waves in the air from the ultrasonic transmission surface 12 to the surface end portion 32a of the steel plate 32 is provided on the ultrasonic transmission surface 12 side. It is formed from the end portion to the end portion on the surface side of the steel plate 32. A slight gap (for example, about 3 to 4 mm) is formed between the distal end surface 14b of the transmission-side ultrasonic shielding cap 14 and the surface end portion 32a of the inspection object 30 (steel plate 32). Alternatively, the front end surface 14 b of the transmission-side ultrasonic shielding cap 14 can be brought into contact with the surface end portion 32 a of the steel plate 32.

  In order to accurately extract only the component focused on the focal point 38 while suppressing the spreading diffracted wave component from the ultrasonic wave receiving surface 22, the transmission side ultrasonic wave shielding cap 14 is increased by increasing the thickness of the transmission side ultrasonic wave shielding cap 14. It is preferable to increase the attenuation amount of the ultrasonic wave in 14. Further, the inner peripheral surface 14a of the through hole 14c of the transmission-side ultrasonic shielding cap 14 has an outer periphery than the conical surface 12a that connects the outer periphery of the ultrasonic transmission surface 12 and the focal point 38 so as not to block the component that is focused on the focal point 38. It is preferable that the distance between the conical surface 12a and the inner peripheral surface 14a is shortened. For this purpose, the inner diameter of the transmission-side ultrasonic shielding cap 14 (the diameter of the through-hole 14c) is such that the surface side of the inspection object 30 (steel plate 32) (the lower side in FIGS. 1 and 3) is the ultrasonic transmission surface 12 side ( It is preferably smaller than the upper side of FIGS. In this case, for example, as shown in FIGS. 1 to 3, the inner diameter of the transmission-side ultrasonic shielding cap 14 (the diameter of the through hole 14 c) is increased from the ultrasonic transmission surface 12 side toward the surface side of the inspection object 30. For example, as shown in FIGS. 7 and 8, the surface of the object 30 to be inspected from the ultrasonic transmission surface 12 side so that the inner peripheral surface 14a is disposed close to the conical surface 12a. It is also possible to gradually reduce the inner diameter (diameter of the through hole 14c) of the transmission-side ultrasonic shielding cap 14 as it goes to the side. In the example shown in FIGS. 1 to 3, the thickness of the transmission-side ultrasonic shielding cap 14 is thicker on the surface side of the inspection object 30 than the ultrasonic transmission surface 12 side. In the example shown in FIG. The thickness of the shielding cap 14 is constant with respect to the ultrasonic transmission direction (perpendicular to the plate surfaces of the steel plates 32 and 34), and in the example shown in FIG. The thickness of the transmission-side ultrasonic shielding cap 14 gradually increases as it moves toward the center.

  Further, when the spread diffracted wave component is subjected to multiple reflection inside the transmission side ultrasonic shielding cap 14 (inner peripheral surface 14a), it causes noise. In order to suppress the multiple reflection of the diffracted wave on the inner peripheral surface 14a, it is preferable that the acoustic impedance of the transmission side ultrasonic shielding cap 14 is lower than the acoustic impedance of the inspection object 30 (steel plates 32, 34). For example, the material of the transmission-side ultrasonic shielding cap 14 can be made of resin (for example, polyacetal) or rubber having a lower acoustic impedance than a metal material.

  As shown in FIGS. 1 to 3, the reception-side ultrasonic shielding cap 24 surrounds the entire circumference of the ultrasonic reception surface 22, and the inspection object 30 (steel plate 34) is surrounded by the periphery of the ultrasonic reception surface 22. A through hole 24c for propagating ultrasonic waves in the air from the ultrasonic wave receiving surface 22 to the back surface edge portion 34b of the steel plate 34 is provided on the ultrasonic wave receiving surface 22 side. It is formed from the end portion to the end portion on the back surface side of the steel plate 34. A slight gap (for example, about 3 to 4 mm) is formed between the front end surface 24b of the reception-side ultrasonic shielding cap 24 and the surface end portion 34b of the inspection object 30 (steel plate 34). Alternatively, the front end surface 24 b of the reception-side ultrasonic shielding cap 24 can be brought into contact with the surface end portion 34 b of the steel plate 34.

  In order to accurately extract only the component that diffuses from the focal point 38 while suppressing the diffracted wave component that bypasses the inspection object 30, by increasing the thickness of the reception-side ultrasonic shielding cap 24, It is preferable to increase the attenuation amount of ultrasonic waves in the reception-side ultrasonic shielding cap 24. Further, the inner peripheral surface 24a of the through hole 24c of the reception-side ultrasonic shielding cap 24 is more peripheral than the conical surface 22a that connects the outer periphery of the ultrasonic reception surface 22 and the focal point 38 so as not to block components diffusing from the focal point 38. It is preferable that the distance between the conical surface 22a and the inner peripheral surface 24a is shortened. For this purpose, the inner diameter of the reception-side ultrasonic shielding cap 24 (the diameter of the through hole 24c) is such that the back side (upper side of FIGS. 1 and 3) of the inspection object 30 (steel plate 34) is the ultrasonic reception surface 22 side (see FIG. It is preferable to be smaller than (lower side of 1, 3). In this case, for example, as shown in FIGS. 1 to 3, the inner diameter of the reception-side ultrasonic shielding cap 24 (the diameter of the through hole 24 c) is increased from the ultrasonic reception surface 22 side toward the back surface side of the inspection object 30. For example, as shown in FIGS. 7 and 8, the back surface of the inspection object 30 can be reduced from the sound receiving / transmitting surface 22 side so that the inner peripheral surface 24 a is arranged close to the conical surface 22 a. The inner diameter of the reception-side ultrasonic shielding cap 24 (the diameter of the through hole 24c) can be gradually reduced toward the side. In the example shown in FIGS. 1 to 3, the receiving-side ultrasonic shielding cap 24 is thicker on the back side of the inspection object 30 than on the ultrasonic receiving surface 22 side. In the example shown in FIG. The thickness of the shielding cap 24 is constant in the ultrasonic wave receiving direction (perpendicular to the plate surfaces of the steel plates 32 and 34), and in the example shown in FIG. The thickness of the reception-side ultrasonic shielding cap 24 gradually increases as it goes to the front.

  In addition, if the ultrasonic waves are multiple-reflected inside the reception-side ultrasonic shielding cap 24 (inner peripheral surface 24a), it causes noise. In order to suppress the multiple reflection of the ultrasonic wave at the inner peripheral surface 24a, it is preferable that the acoustic impedance of the reception-side ultrasonic shielding cap 24 is also lower than the acoustic impedance of the inspection object 30 (steel plates 32 and 34). For example, the material of the reception-side ultrasonic shielding cap 24 can also be made of resin (for example, polyacetal) or rubber having a lower acoustic impedance than a metal material.

  The ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20 to which the transmission-side ultrasonic shielding cap 14 and the reception-side ultrasonic shielding cap 24 having the configuration shown in FIGS. 1 to 3 are respectively attached are sandwiched by the steel plate 33 shown in FIG. FIG. 9 shows the waveform of the ultrasonic signal received by the ultrasonic wave receiving surface 22 when facing each other. When measuring ultrasonic waves, the distance between the ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20 is set to 40 mm, the distance between the tip surface 14b of the transmission-side ultrasonic shielding cap 14 and the surface of the steel plate 33, and the reception side. The distance between the front end surface 24b of the ultrasonic shielding cap 24 and the back surface of the steel plate 33 is about 3.5 mm. FIG. 9 shows the comparison result in addition to the waveform when the distance L from the side surface (end surface) 33c of the steel plate 33 to the central axis of the ultrasonic transmission surface 12 and the ultrasonic reception surface 22 is 5 mm and 20 mm. A waveform (same as the waveform in the lower part of FIG. 6) when the ultrasonic shielding cap 14 and the reception-side ultrasonic shielding cap 24 are not provided (distance L is 20 mm) is also shown.

  The waveform when the distance L is 20 mm is almost the same when the ultrasonic shielding caps 14 and 24 are present (center of FIG. 9) and when the ultrasonic shield caps 14 and 24 are not present (bottom of FIG. 9). It was shown that the sonic shielding caps 14, 24 had no effect. In addition, in the case where the ultrasonic shielding caps 14 and 24 are present, the waveform when the distance L is 5 mm (upper part of FIG. 9) and the waveform when the distance L is 20 mm (center of FIG. 9) is about 140 μs. The waveform was obtained with a similar waveform. However, when the distance L was 5 mm, the subsequent waveform was very disturbed. This indicates that when the distance L is 5 mm, a diffracted wave is measured even if the ultrasonic shielding caps 14 and 24 are present. However, since the diffracted wave is greatly reduced as compared with the case without the ultrasonic shielding caps 14 and 24 (the waveform in FIG. 6), the waveform of the transmitted wave that reaches first can be detected.

  Next, the side surface (end surface) 33c of the steel plate 33 is set to a position x = 0 mm, and the central axes of the ultrasonic transmission surface 12 and the ultrasonic reception surface 22 are set to the inside of the steel plate 33 from the position of 20 mm (x = −20 mm). FIG. 10 shows changes in the amplitude of the ultrasonic signal received by the ultrasonic wave receiving surface 22 when moving outward at a pitch of 0.5 mm to a position of 5 mm (x = 5 mm). FIG. 10 shows a change in the maximum amplitude of the measured waveform between 120 μs and 150 μs, and the vertical axis is displayed in decibels with 2V as a reference (0 dB). The amplitude value at the left end (x = −20 mm) of FIG. 10 corresponds to the amplitude of the center and lower waveforms in FIG. As shown in FIG. 10, when there is no ultrasonic shielding cap 14, 24, the influence of the diffracted wave from the end surface 33 c of the steel plate 33 to about 10 mm (x = −10 mm) is significantly affected. From 10 mm to 15 mm (x = −10 mm to x = −15 mm), an amplitude variation that appears to be caused by interference between the diffracted wave and the transmitted wave appeared. On the other hand, when the ultrasonic shielding caps 14 and 24 are present, they are affected by the diffracted wave from the end face 33c of the steel plate 33 to about 3 mm (x = -3 mm), and between 3 mm and 6 mm from the end face 33c of the steel plate 33 (x =- Although an amplitude fluctuation due to interference is observed at 3 mm to x = −6 mm), the influence of the diffracted wave can be greatly suppressed as compared with the case where the ultrasonic shielding caps 14 and 24 are not provided.

  Next, when the inspection object 30 having the adhesive layer 36 at the ends of the steel plates 32 and 34 is produced and the ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20 are opposed to each other with the inspection object 30 interposed therebetween, Imaging of the amplitude distribution of the ultrasonic signal received by the ultrasonic receiving surface 22 was performed. The inspection object 30 has a structure in which steel plates 32 and 34 (SPC 270) having a thickness of 0.8 mm are bonded to each other with a double-sided tape (adhesive layer) 36. FIG. 11 shows a state in which a double-sided tape (adhesive layer) 36 is installed and the dimensions of each part before the steel plates 32 and 34 are bonded together.

  When the ultrasonic transmission position (adhesion evaluation position) with respect to the inspection object 30 is two-dimensionally moved and scanned by the scanning device 40, the amplitude distribution of the ultrasonic signal corresponding to each ultrasonic transmission position is image processing unit 44. FIG. 12A and 12B show the results obtained by imaging. 12A shows an image of the amplitude distribution when the ultrasonic shielding caps 14 and 24 are not provided, and FIG. 12B shows an image of the amplitude distribution when the ultrasonic shielding caps 14 and 24 are provided. In FIGS. 12A and 12B, the decibel display is performed using 2 V as the maximum amplitude value as a reference (0 dB), and −20 dB to −40 dB is shown by shading. The darker the amplitude, the larger the amplitude. Moreover, the white broken line in FIG. 12A, 12B is the side surfaces (end surface) 32c, 34c (refer FIG. 1) of the test target object 30 (steel plates 32, 34).

  As shown in FIG. 12A, when the ultrasonic shielding caps 14 and 24 are not provided, the white region having a small amplitude is narrowed due to the influence of the diffracted wave, and the presence of the double-sided tape 36 is difficult to understand. Further, even in the region where the presence of the double-sided tape 36 can be confirmed, striped patterns appear along the end surfaces 32c and 34c of the steel plates 32 and 34, and the distribution of the adhesion between the steel plates 32 and 34 and the double-sided tape 36 is determined. It's hard to say. This is a fringe pattern due to the amplitude variation due to the interference between the diffracted wave and the transmitted wave, which appears at x = −10 mm to x = −15 mm in FIG. 10.

  On the other hand, as shown in FIG. 12B, when the ultrasonic shielding caps 14 and 24 are present, the image of the adhesion region of the double-sided tape 36 appears clearly, and the ultrasonic shielding caps 14 and 24 are used to image the adhesion region. It turns out that it has a big effect. From the end faces 32c and 34c of the steel plates 32 and 34 up to about 5 mm from the end faces 32c and 34c, although the reception amplitude appears as a black region due to the influence of the diffracted wave as in the result of FIG. Then, like the result of FIG. 10, the outline of the double-sided tape 36 appears clearly, and the distribution considered to be the adhesive distribution between the steel plates 32 and 34 and the double-sided tape 36 can also be displayed. The white area with small amplitude in the double-sided tape 36 is considered to be an area where the adhesion between the steel plates 32 and 34 and the double-sided tape 36 is insufficient.

  According to the embodiment described above, when evaluating the adhesion by the adhesive layer 36 at the ends of the steel plates 32 and 34, the transmission ultrasonic shielding cap 14 and the reception ultrasonic shielding cap 24 are used to transmit ultrasonic waves. It is possible to suppress the ultrasonic wave transmitted from the surface 12 from bypassing the inspection object 30 and reaching the ultrasonic wave receiving surface 22 as a diffracted wave. Therefore, the amplitude of the transmitted wave that passes through the inspection object 30 (the steel plate 32, the adhesive layer 36, and the steel plate 34) and reaches the ultrasonic wave receiving surface 22 is accurately detected from the received signal at the ultrasonic wave receiving surface 22. Can do. As a result, the adhesion by the adhesive layer 36 at the ends of the steel plates 32 and 34 can be accurately evaluated. Further, the ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20 are installed by installing the transmission ultrasonic shielding cap 14 on the ultrasonic transmission sensor 10 itself and the reception ultrasonic shielding cap 24 on the ultrasonic reception sensor 20 itself. During scanning, the ultrasonic shielding cap 14 and the reception-side ultrasonic shielding cap 24 can be moved together with the ultrasonic transmission surface 12 and the ultrasonic reception surface 22. As a result, the ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20 can be easily scanned while suppressing the diffracted wave.

  Hereinafter, as an ultrasonic inspection method using the ultrasonic inspection apparatus according to the present embodiment, an adhesion evaluation method using the adhesive layer 36 of the steel plates 32 and 34 will be described with reference to the flowchart of FIG. First, in step S101, the ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20 are opposed to each other, and a distance between sensors that can acquire the largest ultrasonic energy is obtained in advance. Next, in step S102, the ultrasonic wave receiving surface in consideration of the distance that the ultrasonic wave propagates in the air, the distance that propagates in the inspection object 30 (the steel plate 32, the adhesive layer 36, and the steel plate 34), and the speed of sound thereof. The time position at which the ultrasonic wave (transmitted wave) reaches 22 is determined.

  In step S103, a time gate is set with a certain width at the time position where the transmitted wave reaches the ultrasonic wave receiving surface 22, and the maximum amplitude value of the ultrasonic signal (transmitted wave) at the time gate is set as a signal processing unit. 42. Next, in step S104, measurement of ultrasonic signals (transmitted waves) is repeated while the ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20 are two-dimensionally moved and scanned by the scanning device 40, and each scanning point (adhesion evaluation) is measured. The maximum amplitude value of the ultrasonic signal (transmitted wave) at the position) is recorded. Next, in step S105, it is determined whether or not scanning of the adhesion evaluation position is completed. When the scanning is not completed (when the determination result of step S105 is NO), the process returns to step S103. On the other hand, when the scanning is completed (when the determination result of step S105 is YES), the process proceeds to step S106.

  In step S106, the distribution of the maximum amplitude value of the ultrasonic signal at each scanning point is acquired, and a region affected by the diffracted wave near the end face is excluded from the adhesion evaluation targets among the scanning points. In step S107, the inspection determination unit 48 determines whether or not the adhesion is good by comparing the maximum amplitude value of the ultrasonic signal with a preset threshold value in the adhesion evaluation target region.

  In the above description, the ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20 are focus sensors, and the ultrasonic transmission surface 12 and the ultrasonic reception surface 22 have a focal point 38 in the inspection object 30 (adhesive layer 36). The case of a concave curved surface shape has been described. However, in this embodiment, the ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20 do not have to be focus type sensors. For example, as shown in FIG. 14, the ultrasonic transmission surface 12 and the ultrasonic reception surface 22 are flat. There may be. In that case, the cylindrical surface 12a extending from the outer periphery of the ultrasonic transmission surface 12 so that the inner peripheral surface 14a of the through hole 14c of the transmission-side ultrasonic shielding cap 14 does not block the ultrasonic component incident on the inspection object 30. It is preferable that the inner peripheral surface 14a is disposed closer to the cylindrical surface 12a while being disposed on the outer peripheral side. Similarly, the inner peripheral surface 24a of the through hole 24c of the reception-side ultrasonic shielding cap 24 is also arranged on the outer peripheral side from the cylindrical surface 22a extending from the outer periphery of the ultrasonic reception surface 22, and the inner peripheral surface 24a is formed on the cylindrical surface 22a. It is preferable to arrange them closely.

  In the above description, the case where the transmission-side ultrasonic shielding cap 14 and the reception-side ultrasonic shielding cap 24 are provided in the ultrasonic transmission sensor 10 and the ultrasonic reception sensor 20 has been described. However, in the present embodiment, only the transmission-side ultrasonic shielding cap 14 can be provided in the ultrasonic transmission sensor 10, or only the reception-side ultrasonic shielding cap 24 can be provided in the ultrasonic reception sensor 20. is there. Even in that case, it is possible to suppress the ultrasonic wave transmitted from the ultrasonic transmission surface 12 from reaching the ultrasonic reception surface 22 as a diffracted wave by bypassing the inspection object 30.

  In the above description, as an application example of the inspection of the inspection object 30 using the ultrasonic inspection apparatus according to the present embodiment, the case of evaluating the adhesion by the adhesive layer 36 of the steel plates 32 and 34 has been described. However, the ultrasonic inspection apparatus according to the present embodiment can be applied to, for example, inspection of internal defects of the inspection object 30 in addition to the evaluation of the adhesion by the adhesive layer 36 of the steel plates 32 and 34.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to such embodiment at all, and it can implement with a various form in the range which does not deviate from the summary of this invention. Of course.

  DESCRIPTION OF SYMBOLS 10 Ultrasonic transmission sensor, 12 Ultrasonic transmission surface, 14 Transmission side ultrasonic shielding cap, 20 Ultrasonic reception sensor, 22 Ultrasonic reception surface, 24 Reception side ultrasonic shielding cap, 30 Inspection object, 32, 34 Steel plate, 36 adhesive layer (double-sided tape), 38 focal points, 40 scanning device, 41 ultrasonic signal supply unit, 42 signal processing unit, 44 image processing unit, 46 display device, 48 inspection determination unit.

Claims (9)

An ultrasonic transmission surface including an ultrasonic transmission surface that is disposed opposite to the surface end of the inspection object and transmits ultrasonic waves to the surface end of the inspection object; and
An ultrasonic receiving surface disposed opposite to the back end of the inspection object so as to face the ultrasonic transmission surface via the inspection object, and transmitted from the ultrasonic transmission surface and transmitted through the inspection object An ultrasonic receiving device including an ultrasonic receiving surface for receiving sound waves;
An ultrasonic inspection apparatus comprising:
The ultrasonic transmission device surrounds the entire circumference of the ultrasonic transmission surface, protrudes from the circumference of the ultrasonic transmission surface to the surface edge of the inspection object, and extends from the ultrasonic transmission surface to the inspection object. A transmitting-side ultrasonic shielding member in which a through hole for allowing ultrasonic waves to propagate in the air to the surface end of the object is formed from the end on the ultrasonic transmission surface side to the end on the surface side of the inspection object. The ultrasonic inspection apparatus further includes a transmission-side ultrasonic shielding member for suppressing the ultrasonic wave transmitted from the transmission surface from reaching the ultrasonic reception surface by bypassing the inspection object. The ultrasonic inspection apparatus according to claim 1,
The ultrasonic transmission surface is a concave curved surface shape where the focal point is located in the inspection object,
The diameter of the through hole formed in the transmission side ultrasonic shielding member is an ultrasonic inspection apparatus in which the surface side of the inspection object is smaller than the ultrasonic transmission surface side. The ultrasonic inspection apparatus according to claim 1 or 2,
An ultrasonic inspection apparatus in which an acoustic impedance of a transmission-side ultrasonic shielding member is smaller than an acoustic impedance of an inspection object. The ultrasonic inspection apparatus according to any one of claims 1 to 3,
The ultrasonic receiving device surrounds the entire circumference of the ultrasonic receiving surface, protrudes from the periphery of the ultrasonic receiving surface to the back end of the inspection object, and extends from the back end of the inspection target. A receiving-side ultrasonic shielding member in which a through hole for propagating ultrasonic waves to the ultrasonic receiving surface in the air is formed from an end on the ultrasonic receiving surface side to an end on the back surface side of the inspection object. An ultrasonic inspection apparatus further including a reception-side ultrasonic shielding member for suppressing the ultrasonic wave transmitted from the transmission surface from reaching the ultrasonic reception surface by bypassing the inspection object. An ultrasonic transmission surface including an ultrasonic transmission surface that is disposed opposite to the surface end of the inspection object and transmits ultrasonic waves to the surface end of the inspection object; and
An ultrasonic receiving surface disposed opposite to the back end of the inspection object so as to face the ultrasonic transmission surface via the inspection object, and transmitted from the ultrasonic transmission surface and transmitted through the inspection object An ultrasonic receiving device including an ultrasonic receiving surface for receiving sound waves;
An ultrasonic inspection apparatus comprising:
The ultrasonic receiving device surrounds the entire circumference of the ultrasonic receiving surface, protrudes from the periphery of the ultrasonic receiving surface to the back end of the inspection object, and extends from the back end of the inspection target. A receiving-side ultrasonic shielding member in which a through hole for propagating ultrasonic waves to the ultrasonic receiving surface in the air is formed from an end on the ultrasonic receiving surface side to an end on the back surface side of the inspection object. An ultrasonic inspection apparatus further including a reception-side ultrasonic shielding member for suppressing the ultrasonic wave transmitted from the transmission surface from reaching the ultrasonic reception surface by bypassing the inspection object. The ultrasonic inspection apparatus according to claim 4, wherein:
The ultrasonic receiving surface is a concave curved surface shape in which the focal point is located in the inspection object,
The diameter of the through hole formed in the reception-side ultrasonic shielding member is an ultrasonic inspection apparatus in which the back surface side of the inspection object is smaller than the ultrasonic reception surface side. The ultrasonic inspection apparatus according to any one of claims 4 to 6,
An ultrasonic inspection apparatus in which an acoustic impedance of a reception-side ultrasonic shielding member is smaller than an acoustic impedance of an inspection object. The ultrasonic inspection apparatus according to any one of claims 1 to 7,
The inspection object has the first plate-like member and the second plate-like member joined to each other via an adhesive layer at the end,
The ultrasonic transmission surface is disposed opposite to the surface end of the first plate member, and transmits ultrasonic waves to the adhesive layer via the first plate member.
The ultrasonic wave receiving surface is arranged to face the back surface end of the second plate member so as to face the ultrasonic wave transmitting surface via the first plate member, the adhesive layer, and the second plate member, and from the ultrasonic wave transmitting surface. An ultrasonic inspection apparatus that receives ultrasonic waves transmitted and transmitted through a first plate member, an adhesive layer, and a second plate member. An ultrasonic inspection method using the ultrasonic inspection apparatus according to any one of claims 1 to 8,
While the ultrasonic transmission position with respect to the inspection object is two-dimensionally moving and scanned, the ultrasonic wave transmitted from the ultrasonic transmission apparatus and transmitted through the inspection object is received by the ultrasonic reception apparatus,
An ultrasonic inspection method for inspecting an inspection object based on an amplitude of an ultrasonic wave corresponding to each ultrasonic transmission position received by an ultrasonic receiver.