Ultrasonic inspection device, ultrasonic inspection method, and contact member

Abstract

To provide a sonic inspection device in which, at inspection time, a couplant can be in close contact with an inspection object, and the couplant can be easily moved, and which has an S / N suppressed in deterioration.SOLUTION: A sonic inspection deice 1 of an embodiment comprises: a sonic probe 2 which comprises a vibrator having at least one of functions of transmitting a sound wave and of receiving a sound wave and which has a sonic function surface 2a functioning as at least one of surfaces for transmitting the sound wave and for receiving the sound wave; a contact member 9 including a couplant 10 and a sheet member 12, the couplant 10 being in contact with the sonic function surface 2a of the sonic probe 2 directly or through an intermediate member and containing an elastomer, and a sheet member 12 being in contact with the couplant 10 and having a plurality of holes 11; and a loading mechanism 13 which applies / removes a load to / from the contact member 9. The sheet member 12 has a thickness in the range of 0.15 times to 0.35 times the wavelength λ of a sound wave propagating in the couplant 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to an ultrasonic inspection device, an ultrasonic inspection method, and a contact member. [Background technology]

[0002] Sonic inspection devices that use the propagation of sound waves such as ultrasound and elastic waves are used to inspect various components, devices, infrastructure, etc. Ultrasonic inspection devices are also used in medical diagnoses, etc. When an ultrasonic inspection probe, such as an ultrasonic receiver, an ultrasonic transmitter, or an ultrasonic transceiver, typified by an ultrasonic probe or an acoustic emission (AE) sensor, used in such inspection devices, is installed on an object to be inspected, a liquid or viscous couplant, such as glycerin or petrolatum, is interposed between the object and the sonic functional surface, which functions as at least one of the sound wave transmitting and receiving surfaces of the probe, in order to efficiently propagate sound waves between the object and the sonic functional surface.

[0003] The above-mentioned couplant is important for efficiently transmitting sound waves, such as ultrasonic waves, from the probe to the test object or from the test object to the probe, thereby improving test accuracy. However, the process of applying and removing liquid or viscous couplant is complicated. This increases the time and labor required for testing. Furthermore, depending on the test object, the test object may be contaminated with couplant, making it impossible to perform the test itself.

[0004] Solid couplants have also been proposed, but their ultrasonic propagation is significantly inferior to that achieved with liquid couplants. This is thought to be due to the presence of air, which has a significantly different acoustic impedance, between the probe's couplant and the test object. Adhesive solid couplants have also been proposed to avoid the air gap between the test object and the couplant's mounting surface. However, in this case, the couplant's mounting surface adheres tightly to the test object, preventing the couplant from sliding. As a result, even for small distances, the probe and couplant must be removed from the test object, complicating the testing process. Furthermore, when transmitting and receiving sound waves from a test probe through a couplant, it is necessary to minimize the attenuation of sound and reflected waves due to the couplant and the reduction in S / N ratio caused by multiple reflections. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2017 / 024704 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to inspect an object under inspection without contaminating the object with a liquid couplant. The present invention provides an ultrasonic inspection device, an ultrasonic inspection method, and a contact member that enable the couplant to be brought into close contact with the object under inspection during inspection, the couplant to be easily moved over the object under inspection, and the S / N ratio to be reduced. [Means for solving the problem]

[0007] One aspect of the ultrasonic inspection device of the embodiment includes an ultrasonic probe having a transducer capable of at least one of transmitting and receiving sound waves and having an ultrasonic functional surface functioning as at least one of the transmitting and receiving surfaces of sound waves, a contact member having a first surface in contact with the ultrasonic functional surface of the ultrasonic probe directly or via an intermediate member and a second surface opposite to the first surface, the contact member including at least an elastomer, and a sheet member having a plurality of holes disposed in contact with the second surface of the contact medium, and a loading mechanism for applying and removing a load to the contact member. The sheet member in this aspect of the ultrasonic inspection device of the embodiment has a thickness in the range of 0.15 to 0.35 times the wavelength λ of the sound waves propagating through the contact medium. Furthermore, the sheet member has the plurality of holes arranged so that the closest distance between a first hole and a second hole adjacent to the first hole is in the range of 0.1 to 1.5 times the wavelength λ of the sound wave.

[0008] Another aspect of the ultrasonic inspection device of the embodiment includes an ultrasonic probe having a transducer capable of at least one of transmitting and receiving ultrasonic waves and having an ultrasonic functional surface functioning as at least one of the transmitting surface and receiving surface of ultrasonic waves, a contact member having a first surface in contact with the ultrasonic functional surface of the ultrasonic probe directly or via an intermediate member and a second surface opposite to the first surface, the contact member including at least an elastomer, a sheet member having a plurality of holes arranged to contact the second surface of the contact medium, and a loading mechanism for applying and removing a load to the contact member. In another aspect of the ultrasonic inspection device of the embodiment, the sheet member has the plurality of holes arranged so that the distance between a first hole and a second hole adjacent to the first hole is in the range of 0.1 to 1.5 times the wavelength λ of ultrasonic waves propagating through the contact medium. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an ultrasonic inspection device according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing an ultrasonic probe in the ultrasonic inspection device shown in FIG. [Figure 3]1. FIG. 4 is a cross-sectional view showing a first example of a combination of an ultrasonic probe and a contact member in the ultrasonic inspection device shown in FIG. [Figure 4] 4 is a plan view showing a first example of a sheet member in the contact member shown in FIG. 3. FIG. [Figure 5] 1. FIG. 4 is a cross-sectional view showing a second example of a combination of an ultrasonic probe and a contact member in the ultrasonic inspection device shown in FIG. [Figure 6] 4 is a plan view showing a second example of a sheet member in the contact member shown in FIG. 3. FIG. [Figure 7] 4 is a plan view showing a third example of a sheet member in the contact member shown in FIG. [Figure 8] 3. FIG. 6 is a plan view showing a fourth example of a sheet member in the contact member shown in FIG. [Figure 9] 3. FIG. 9 is a plan view showing a fifth example of a sheet member in the contact member shown in FIG. [Figure 10] 3. FIG. 9 is a plan view showing a sixth example of a sheet member in the contact member shown in FIG. [Figure 11] 4 is a cross-sectional view showing a state before a load is applied to the contact member shown in FIG. 3. FIG. [Figure 12] 4 is a cross-sectional view showing a state in which a load is applied to the contact member shown in FIG. 3. FIG. [Figure 13] 10 is a diagram showing the dependency of the reflected wave amplitude width on the ratio of the closest distance between holes to the acoustic wavelength in the ultrasonic inspection device of Example 1. FIG. [Figure 14] 10 is a diagram showing the amplitude of a reflected wave and the amplitude of multiple reflected waves in an ultrasonic inspection carried out using the ultrasonic inspection device of Example 2. FIG. [Figure 15] FIG. 10 is a diagram showing the dependency of the ratio of the amplitude of multiple reflected waves to the amplitude width of the reflected waves on the ratio of the sheet member to the acoustic wavelength in the ultrasonic inspection device of Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0010] The ultrasonic inspection device and ultrasonic inspection method according to the embodiments will be described below with reference to the drawings. In each embodiment, substantially identical components are designated by the same reference numerals, and some of their descriptions may be omitted. The drawings are schematic, and the relationship between the thickness of each component and its planar dimensions, the thickness ratio of each component, etc. may differ from the actual ones. Terms indicating the up-down direction in the description refer to the relative direction when the inspection surface of the object to be inspected is considered to be up, and may differ from the actual direction based on the direction of gravitational acceleration.

[0011] FIG. 1 is a diagram showing an ultrasonic inspection device according to an embodiment. The ultrasonic inspection device 1 shown in FIG. 1 has a vertical ultrasonic probe 2 and performs non-destructive inspection by measuring sound waves (reflected waves) returning from an object to be inspected, such as a flaw, or sound waves generated by the object to be inspected. The ultrasonic probe 2 has the function of transmitting and receiving at least one of sound waves, and specific examples include an ultrasonic transmitter / receiver and an ultrasonic receiver. A typical example of an ultrasonic transmitter / receiver is an ultrasonic probe. A typical example of an ultrasonic receiver is an AE sensor. The ultrasonic probe 2 may also be an ultrasonic transmitter.

[0012] The term "sound waves" used herein is a general term for all elastic vibration waves that propagate through an elastic body, whether gas, liquid, or solid, and includes not only sound waves in the audible frequency range but also ultrasonic waves having frequencies higher than the audible frequency range and low-frequency sounds having frequencies lower than the audible frequency range. The frequency of the sound waves is not particularly limited and includes frequencies from high to low. In the ultrasonic inspection device 1 of the embodiment, the ultrasonic probe 2 has an ultrasonic wave transmitting / receiving surface, a receiving surface, a transmitting surface, etc. Here, the surface of the ultrasonic probe 2 that functions as at least one of the ultrasonic wave transmitting surface and receiving surface is referred to as the ultrasonic functional surface. The ultrasonic probe 2 is equipped with such an ultrasonic functional surface 2a.

[0013] In the ultrasonic inspection device 1 shown in FIG. 1, the ultrasonic probe 2 is, for example, an ultrasonic probe serving as an ultrasonic transmitter / receiver. As shown in FIG. 2, the ultrasonic probe 2 includes an ultrasonic flaw detection vibrator (piezoelectric element) 3 and an ultrasonic transmitter / receiver element 5 having electrodes 4 provided on both the upper and lower surfaces of the vibrator 3. The ultrasonic transmitter / receiver element 5 is disposed on a wave receiving plate 6 and is housed in a case 7 in this state. The electrodes 4 of the ultrasonic transmitter / receiver element 5 are electrically connected to a connector 8 provided on the case 7. The vibrator 3, the ultrasonic transmitter / receiver element 5, the wave receiving plate 6, etc. may be made of materials and structures used in known ultrasonic probes, and are not particularly limited. Furthermore, when the ultrasonic probe 2 is an ultrasonic receiver such as an AE sensor, a similar configuration to that of an ultrasonic probe is applied, except that an ultrasonic receiving element having an AE receiving vibrator (piezoelectric element) 3 is used. In this case, the AE receiving vibrator 3, the ultrasonic receiving element, the wave receiving plate 6, etc. may be made of materials and structures used in known AE sensors.

[0014] When an ultrasonic probe is used as the ultrasonic probe 2, applying a voltage to the transducer 3 from the electrode 4 transmits ultrasonic waves via the receiving plate 6, and receives reflected ultrasonic waves via the receiving plate 6. In the ultrasonic probe, the surface 6b of the receiving plate 6 opposite to the surface 6a that contacts the ultrasonic transmitting / receiving element 5 serves as the ultrasonic transmitting and receiving surface (transmitting / receiving surface). When an AE sensor is used as the ultrasonic probe 2, the transducer 3 receives sound waves (elastic waves) generated by AE (Acoustic Emission) within the subject via the receiving plate 6. In the AE sensor, the surface 6b of the receiving plate 6 opposite to the surface 6a that contacts the ultrasonic receiving element 5 serves as the acoustic wave receiving surface. In the ultrasonic probe 2, the surface 6b of the receiving plate 6 on which the ultrasonic transmitting / receiving element or the ultrasonic receiving element (hereinafter sometimes collectively referred to as the acoustic element) 5 is arranged serves as the acoustic functional surface 2a that functions as at least one of the transmitting surface and the receiving surface of the sound waves.

[0015] The acoustic functional surface 2a of the acoustic probe 2 is provided with a contact member 9 that functions as an acoustic wave propagation section. As shown in Figures 3 and 4, the contact member 9 comprises a couplant 10 containing an elastomer and a sheet member 12 with a plurality of holes 11. Figure 3 is an enlarged cross-sectional view of the contact member 9, and Figure 4 is a plan view showing the shape of the holes 11 in the sheet member 12. The couplant 10 has a first surface 10a that contacts the acoustic functional surface 2a of the acoustic probe 2 directly or via an intermediate member, and a second surface 10b opposite the first surface 10a. The first surface 10a of the couplant 10 is bonded to the acoustic functional surface 2a of the acoustic probe 2 directly or via an intermediate member with an adhesive (not shown). Examples of intermediate members include a shoe made of a polymer material and a bonding layer. The sheet member 12 has a third surface 12a provided to contact the second surface 10b of the contact medium 10, and a fourth surface 12b opposite to the third surface 12a. The third surface 12a of the sheet member 12 is adhered to the second surface 10b of the contact medium 10 with an adhesive (not shown). The fourth surface 12b of the sheet member 12 forms a contact surface with the test object X.

[0016] The ultrasonic probe 2 and the contact member 9 may be bonded to each other by a bonding layer 14 disposed between the acoustic functional surface 2a and the first surface 10a, as shown in FIG. 5 . The bonding layer 14 may be configured, for example, by sequentially disposing a first reversible adhesive layer 15, a polymer layer 16, and a second adhesive layer 17. These layers 15, 16, and 17 will be described in detail later. By using the reversible first adhesive layer (reversible adhesive layer) 15, the contact member 9 can be easily attached to and detached from the ultrasonic probe 2. For example, the object X to be inspected is not limited to a bulk solid, but may also be an aggregate of powder or a compacted powder. In such an inspection, powder as the object X to be inspected adheres to the contact member 9, making it necessary to replace the contact member 9. By easily attaching and detaching the contact member 9 to and from the ultrasonic probe 2, the inspection efficiency of the object X to be inspected, such as an aggregate of powder, can be improved.

[0017] FIG. 4 shows a state in which the plurality of holes 11 in the sheet member 12 are circular holes arranged in a 60° staggered pattern. In this case, the distance between adjacent holes 11 is approximately the same. The arrangement of the plurality of holes 11 is not limited to the arrangement shown in FIG. 4. For example, as shown in FIG. 6, the circular holes as the plurality of holes 11 may be arranged in parallel. Furthermore, the circular holes may be arranged in a 45° staggered pattern, etc. The shape of the holes 11 is also not limited to a circular hole, and may be a rectangular hole such as a square hole (rectangular hole) shown in FIG. 7 or a hexagonal hole (polygonal hole) shown in FIG. 8, an elongated hole shown in FIG. 9, or an oblong hole shown in FIG. 10. Various arrangements such as a staggered pattern or a parallel pattern can be applied to the arrangement of the rectangular holes, elongated holes, and oblong holes. In all of FIGS. 4, 6, 7, 8, 9, and 10, the black portions indicate the positions of the holes 11 (portions where the holes 11 are opened), and the white portions indicate portions of the sheet member 12 where the holes 11 are not opened.

[0018] The ultrasonic inspection device 1 is disposed so that the fourth surface 12b of the sheet member 12 contacts the object to be inspected (object to be treated) X. The ultrasonic inspection device 1 has a loading jig 13 attached to the outer periphery of the ultrasonic probe 2. In the ultrasonic inspection device 1, a load is first applied to the ultrasonic probe 2 via the loading jig 13, and then a load is applied to the contact member 9 via the ultrasonic probe 2. As will be described later, the load applied to the contact member 9 causes the couplant 10 to contact the object to be inspected X through the multiple holes 11 in the sheet member 12. Therefore, acoustic waves can be efficiently propagated between the couplant 10 and the object to be inspected X, enabling accurate nondestructive inspection of the object to be inspected X. Furthermore, by removing the load applied by the loading jig 13, only the sheet member 12 contacts the object to be inspected X, allowing the ultrasonic inspection device 1 to be slidably moved over the object to be inspected X. This allows the ultrasonic inspection device 1 to be easily moved to the next inspection position of the object under inspection X. A load can be applied to the couplant 10 by various mechanisms and methods for applying a force to the couplant 10. For example, a load can be applied to the couplant 10 by an electric actuator using a stepping motor or an AC servo motor, or an actuator using hydraulic or pneumatic pressure.

[0019] The couplant 10 contains at least an elastomer and has a contact surface for contacting the test object X, as described above. When no load is applied to the contact member 9 by the loading jig 13, the second surface 10b of the couplant 10 is simply in contact with the third surface 12a of the sheet member 12, as shown in FIG. 11 . Therefore, the couplant 10 is not in contact with the test object X, and only the fourth surface 12b of the sheet member 12 is in contact with the test object X. In this state, the ultrasonic inspection device 1 is simply moved without performing an ultrasonic inspection. Due to the slipperiness, etc., of the constituent material of the sheet member 12, which will be described later, when only the sheet member 12 is in contact, the ultrasonic inspection device 1 can be moved over the test object X while sliding via the sheet member 12.

[0020] On the other hand, as shown in FIG. 12 , when a load P is applied to the contact member 9 by the load application jig 13, the deformation characteristics of the couplant 10, which contains at least an elastomer, i.e., its ultra-low elastic modulus, large reversible deformation, and viscoelasticity, cause a portion of the couplant 10 to deform so as to fill the holes 11 in the sheet member 12. This deformation of the couplant 10 due to the applied load places a portion of the couplant 10 in contact with the test object X. Similar to a liquid contact medium, a viscous elastomer can effectively propagate sound waves, such as ultrasonic waves. Therefore, by placing a portion of the couplant 10 in contact with the test object X, sound waves can be efficiently propagated between the couplant 10 and the test object X when the load P is applied. These features enable both improved accuracy in nondestructive testing of the test object X by the ultrasonic inspection device 1 and improved mobility of the ultrasonic inspection device 1 over the test object X.

[0021] When measuring the frictional force of elastomers, they are overwhelmingly larger than that of other materials, sometimes exceeding 1. This large frictional force originates from the adhesive force of the elastomer to the test object X, which originates from van der Waals forces. This phenomenon is observed because the contact area becomes extremely large due to deformation. When hard materials such as metals are brought into contact with each other, only a small portion of the contact surface, the roughness—specifically, the tips of the microscopic protrusions—makes contact. However, when the elastic modulus is low, as in elastomers, the contact area increases even with the same load, and the adhesive force increases accordingly. Furthermore, the viscoelasticity of elastomers increases the force required to peel the adhesive interface, which also increases the coefficient of friction. Thus, due to the large effective (microscopic) contact area between elastomers and the test object X, they are highly transparent to ultrasound. However, the more ultrasonically permeable a material is, the greater the frictional force, making peeling more difficult. Therefore, in the contact member 9, as shown in FIG. 3, a sheet member 12 having a plurality of holes 11 is provided on the surface 10b of the contact medium 10, which makes it easy to move when there is no load.

[0022] The elastic constant (Young's modulus) of the elastomer used as the couplant 10 is preferably 0.1 MPa or more and 10 MPa or less. Examples of thermoplastic elastomers that may be used to form the couplant 10 include polystyrene thermoplastic elastomers (SBC, TPS), polyolefin thermoplastic elastomers (TPO), vinyl chloride thermoplastic elastomers (TPVC), polyurethane thermoplastic elastomers (TPU), polyester thermoplastic elastomers (TPEE, TPC), and polyamide thermoplastic elastomers. Thermosetting elastomers include diene rubbers such as styrene-butadiene rubber (SBR), isoprene rubber (IR), butadiene rubber (BR), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR); non-diene rubbers such as isobutylene-isoprene rubber (IIR), butyl rubber, ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), urethane rubber (U), silicone rubber, and fluororubber (FKM). Other examples of rubbers include chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM), acrylic rubber (ACM), polysulfide rubber (T), and epichlorohydrin rubber (CO, ECO). Since each material has its own unique characteristics, such as heat resistance, abrasion resistance, oil resistance, and chemical resistance, it is best to select the appropriate elastomer for the test subject. Depending on the application, multiple elastomers may be mixed. Additives of a size that does not impede the transmission of sound waves, that is, an additive of a diameter of approximately 200 μm or less, may be mixed in.

[0023] It is more preferable that the elastomer constituting the contact medium 10 contains at least one selected from the group consisting of polyester-based thermoplastic elastomer, styrene-butadiene rubber, isoprene rubber, butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, isobutylene-isoprene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, silicone rubber, fluororubber, chlorosulfonated polyethylene, acrylic rubber, and epichlorohydrin rubber, which have excellent heat resistance.

[0024] The material constituting the sheet member 12 is preferably one having a higher elastic modulus than the elastomer constituting the couplant 10. Examples of suitable materials include fluororesins such as polytetrafluoroethylene, perfluoroalkoxyalkane, perfluoroethylenepropene copolymer, ethylenetetrafluoroethylene copolymer, polyvinylidene fluoride, polychlorotrifluoroethylene, and ethylenechlorotrifluoroethylene copolymer; resins such as polyester resin, nylon resin, polyethylene resin, polypropylene resin, fluorine-based resin, and polyvinyl chloride resin; metal materials; ceramic materials; and compound materials such as oxides. The sheet member 12 is preferably made of a material having a higher elastic modulus than the elastomer constituting the couplant 10 and excellent slip properties. Since the propagation of sound waves such as ultrasonic waves is primarily mediated by the couplant 10 in the contact member 9, the propagation of sound waves need not be considered for the sheet member 12.

[0025] The material constituting the contact medium 10 may contain a slide-ring elastomer. This lowers the Young's modulus of the elastomer and reduces hysteresis. Slide-ring elastomers are slide-ring polymer materials, typified by polyrotaxane structures, known for their extremely low Young's modulus. Rotaxanes consist of large ring molecules threaded through rod-like molecules, with bulky moieties attached to both ends of the axis, preventing the ring from slipping off the axis due to steric hindrance. Their structural features can be classified into three categories: (1) there is no covalent bond between the ring molecules and the linear polymer; (2) numerous ring molecules can rotate and slide along the linear polymer; and (3) the ring molecules in the polyrotaxane can be chemically modified to impart functionality.

[0026] The slide-ring elastomer described above is preferably a polyrotaxane using polyethylene glycol as the axial molecule, a cyclodextrin derivative as the cyclic molecule, and adamantane as the capping molecule. In particular, an elastomer obtained by grafting polycaprolactone or the like onto a polyrotaxane and blending it with other polymers and crosslinking it has an extremely low modulus of elasticity, on the order of 1 kPa. By using such an elastomer as a constituent material, it is possible to further improve the conformability to the surface of the test object X having irregularities. Furthermore, hysteresis is reduced, allowing for increased continuous use.

[0027] As described above, when ultrasonic waves or the like are transmitted from the acoustic wave element 5 to the test object X while a portion of the couplant 10 is in contact with the test object X due to an applied load, the ultrasonic waves propagate through the couplant 10, reach the test object X via the contact interface between the couplant 10 and the test object X, and propagate through the test object X. During this process, some of the ultrasonic waves are reflected by the sheet member 12, and these unwanted reflected waves may form multiple reflected waves together with reflected waves reflected by flaws or other defects in the test object X. Such multiple reflected waves may degrade the signal characteristics of the reflected waves reflected by flaws or other defects in the test object X. In other words, they may reduce the S / N ratio of the signal due to the reflected waves that are the intended target. Therefore, in the ultrasonic inspection device 1 of this embodiment, the thickness of the sheet member 12 (thickness T shown in FIG. 3 ) is set to a value in the range of 0.15 to 0.35 times the wavelength λ of the ultrasonic waves propagating through the couplant 10.

[0028] By using a sheet member 12 having a thickness in the range of 0.15λ to 0.35λ inclusive relative to the ultrasonic waves (wavelength λ) propagating through the couplant 10, multiple reflections of reflected waves can be reduced within the couplant 10. For example, when the thickness of the sheet member 12 is 0.25λ (¼λ), multiple reflections can be reduced by the half-wavelength phase shift and cancellation. This multiple reflection reduction effect can be achieved more effectively by setting the thickness of the sheet member 12 in the range of 0.15λ to 0.35λ inclusive compared to when the thickness of the sheet member 12 is less than 0.15λ or exceeds 0.35λ. It is more preferable that the thickness of the sheet member 12 be in the range of 0.2λ to 0.3λ inclusive. The above-mentioned multiple reflection reduction effect can be achieved not only for ultrasonic waves but also for sounds in general, and can also be achieved for sounds emitted from the test object X and reaching the acoustic wave element 5.

[0029] Furthermore, in order to reduce the multiple reflections and attenuation caused by the sheet member 12, it is also effective to adjust the closest distance between the multiple holes 11 formed in the sheet member 12. Specifically, as shown in FIGS. 3 and 4, it is effective to set the distance (closest distance) W between a first hole 11A and a second hole 11B adjacent to the first hole 11A within the range of 0.1 to 1.5 times the wavelength λ of the ultrasonic waves propagating through the couplant 10. Furthermore, it is preferable to set the distance (closest distance) W between adjacent holes 11 within each of the multiple holes 11 within the range of 0.1λ to 1.5λ. In this way, by setting the closest distance W between the multiple holes 11 within the range of 0.1λ to 1.5λ, ultrasonic waves propagating through the couplant 10 can easily pass through, thereby reducing multiple reflections of reflected waves within the couplant 10 and attenuation of sound waves by the sheet member 12. It is more preferable that the closest spacing W between the plurality of holes 11 provided in the sheet member 12 is in the range of 0.1λ to 1λ. Such an effect of reducing multiple reflections of ultrasonic waves and attenuation by the sheet member 12 can be obtained not only for ultrasonic waves but also for sounds in general, and can also be obtained for sounds emitted from the test object X and reaching the acoustic wave element 5.

[0030] Even when applying either the above-mentioned configuration in which the thickness of the sheet member 12 is in the range of 0.15λ or more and 0.35λ or less, or the configuration in which the closest interval W between the plurality of holes 11 is in the range of 0.1λ or more and 1.5λ or less, it is possible to reduce multiple reflections and attenuation caused by the sheet member 12. In order to reduce multiple reflections and attenuation caused by the sheet member 12 and further increase the S / N ratio of the acoustic signal received by the acoustic wave element 5, it is preferable to apply both the configuration in which the thickness of the sheet member 12 is in the range of 0.15λ or more and 0.35λ or less, and the configuration in which the interval W between the plurality of holes 11 is in the range of 0.1λ or more and 1.5λ or less.

[0031] In the ultrasonic inspection device 1 of the embodiment, the thickness of the couplant 10 is preferably 10 μm or more and 10 mm or less. The optimum thickness varies depending on the acoustic impedance and Young's modulus of the material constituting the couplant 10, but a thickness of approximately 0.5 mm or more and 2 mm or less can improve sound wave propagation performance. The elastomer used in the embodiment has a certain degree of viscoelasticity and can adhere to the object. Therefore, it does not contaminate the surroundings as compared with other couplants such as water or oil. Furthermore, because it is solid, it is easy to remove and can be reused. To eliminate air gaps by pressing the couplant 10, the elastic constant (Young's modulus) of the elastomer used is preferably 0.1 MPa or more and 0.1 GPa or less.

[0032] 3 to 10, the total area of ​​the holes 11 (the area of ​​the black portions in FIGS. 4, 6 to 10) is preferably equal to or greater than the area of ​​the portion of the seed member 12 where the holes 11 are not formed (the area of ​​the white portions in FIGS. 4, 6 to 10). This ensures a sufficient contact area between the couplant 10 and the test object X, thereby improving the accuracy of sonic testing such as ultrasonic testing. Furthermore, the thickness of the seed member 12, the minimum width of the portion of the seed member 12 where the holes 11 are not formed, and the ratio of the total area of ​​the holes 11 in the sheet member 12 to the area of ​​the portion of the sheet member 12 where the holes 11 are not formed, etc., are preferably selected appropriately depending on the Young's modulus, acoustic impedance, etc., of the material used for the couplant 10.

[0033] In the bonding layer 14 shown in FIG. 5, the first adhesive layer (reversible adhesive layer) 15, which has reversibility, contains, for example, a temperature-sensitive adhesive, a light-irradiation curing agent, a heat-foaming agent, a thermal expansion agent, or a photostructural change agent, and thereby changes its adhesive strength in response to changes in stimuli or the environment. By providing such a reversible adhesive layer 15, the contact member 9 can be quickly removed from the ultrasonic probe 2 when desired by using light irradiation, temperature change, or the like. The polymer layer 16 and the second adhesive layer 17 are provided between the reversible adhesive layer 15 and the contact medium 10, and may be required when integrating these two, and are provided as needed.

[0034] The reversible adhesive layer 15 preferably has a thickness of, for example, 10 μm or more and 100 μm or less. An example of the reversible adhesive layer 15 is a temperature-sensitive adhesive layer whose adhesiveness decreases at low temperatures. The temperature-sensitive adhesive layer contains a side-chain crystalline polymer as a main component, and when cooled to a temperature below the melting point of the side-chain crystalline polymer, the side-chain crystalline polymer crystallizes, causing the adhesive strength to decrease. Examples of the side-chain crystalline polymer that can be used include various side-chain crystalline methacrylic resins.

[0035] Another example of the reversible adhesive layer 15 is a temperature-sensitive adhesive layer whose adhesiveness decreases at high temperatures. Known examples of such temperature-sensitive adhesive layers include those containing a side-chain crystalline polymer and a foaming agent. The temperature-sensitive adhesive layer contains a side-chain crystalline polymer as the main component, and a foaming agent in a ratio of 1 to 60 parts by weight per 100 parts by weight of the side-chain crystalline polymer. When the temperature-sensitive adhesive layer is heated to a temperature equal to or higher than the foaming temperature of the foaming agent, the side-chain crystalline polymer becomes fluid, reducing the cohesive force of the adhesive layer. At the same time, the foaming agent foams and expands, allowing the contact member 9 to be easily removed from the ultrasonic probe 2.

[0036] Examples of side-chain crystalline polymers include methacrylate resins. Chemical foaming agents and physical foaming agents can be used as foaming agents. Chemical foaming agents include thermally decomposable and reactive organic foaming agents, as well as inorganic foaming agents. Examples of thermally decomposable organic foaming agents include various azo compounds, nitroso compounds, and hydrazine derivatives. Examples of reactive organic foaming agents include isocyanate compounds. Examples of thermally decomposable inorganic foaming agents include bicarbonates and carbonates. Commercially available microencapsulated thermally expandable microparticles can be used as other foaming agents. The average particle size of the foaming agent is preferably 5 to 50 μm.

[0037] Yet another example of the reversible adhesive layer 15 is a photocurable release layer. The photocurable release layer contains, for example, 100 parts by weight of a methacrylic polymer, which is a side-chain crystalline block copolymer, and 0.1 to 2 parts by weight of a photopolymerization initiator. Furthermore, one type of photopolymerization initiator may be used alone, or two or more types of photopolymerization initiators may be used in combination.

[0038] The polymer layer 16 is preferably in the form of a film. The term "film-like" is not limited to film, but rather encompasses films, sheets, and the like, as long as the effects of the embodiment are not impaired. Examples of materials constituting the polymer layer 15 include synthetic resins such as polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-polypropylene copolymer, and polyvinyl chloride. The polymer layer 16 may be either a single layer or a multi-layer, and its thickness is preferably 5 to 250 μm. The polymer layer 16 may be subjected to surface treatment, such as corona discharge treatment, plasma treatment, blast treatment, chemical etching treatment, or primer treatment, in order to enhance adhesion to the second adhesive layer 17.

[0039] The second adhesive layer 17 is provided to bond the polymer layer 16 to the couplant 10 containing an elastomer. For example, a rubber-based solvent adhesive can be used as the second adhesive layer 17. Examples of rubber-based solvent adhesives that can be used include SBS (styrene-butadiene-styrene) resin adhesives and chloroprene rubber adhesives. During bonding, surface treatments such as corona discharge treatment, plasma treatment, blast treatment, chemical etching treatment, and primer treatment can be performed. [Example]

[0040] Examples and their evaluation results will be described below.

[0041] (Example 1, Comparative Example 1) First, a styrene-butadiene elastomer (containing process oil, JIS type E hardness 4, sound velocity under experimental conditions 1350 m / s) was prepared as an elastomer sheet. Next, a 150 μm thick polytetrafluoroethylene sheet was prepared, corresponding to 0.25 times the wavelength λ of the 2.25 MHz ultrasonic wave in the elastomer. Holes with a diameter of 100 μm were drilled all over the sheet at various pitches (nearest distance). The perforated sheet was then placed in close contact with the elastomer sheet to form a contact member.

[0042] A 25 μm-thick polymer layer (PET sheet) was adhered to the elastomer on the side not adhered to the polytetrafluoroethylene sheet using an ultrathin SBS adhesive. The PET sheet was laminated to the ultrasonic transmission / reception surface of a 2.25 MHz ultrasonic probe via a reversible adhesive layer. In this way, the reversible adhesive layer, polymer layer, adhesive layer, elastomer member, and polytetrafluoroethylene sheet were laminated on the ultrasonic probe in this order. The reversible adhesive layer used here was a temperature-sensitive adhesive layer whose adhesiveness decreases at high temperatures, and a 30 μm-thick layer was used, which was a mixture of 100 parts by weight of polymethacrylate resin and 30 parts by weight of microencapsulated thermally expandable particles (manufactured by Nippon Phillite Co., Ltd., Expancel (registered trademark)).

[0043] First, a shear tensile test was conducted to determine whether the probe could be moved under its own weight alone without any additional load. A load cell was connected to the ultrasonic probe, which was then placed on a stainless steel plate with a surface roughness Rz of 32 μm. The stainless steel plate was then moved at a slow speed to measure the static friction coefficient. As a comparative example, a similar measurement was performed on an elastomer sheet without a sheet member attached. The results showed that without a sheet member, the static friction coefficient was extremely high, making it difficult to move the probe. In contrast, with a sheet member attached, the static friction coefficient was uniformly small, making it possible to move the probe. However, when the closest distance between the holes was 0.1 wavelength or less (60 μm or less in this example), the elastomer protruded from the surface of the sheet member, making smooth movement of the probe difficult.

[0044] Next, ultrasonic testing was performed. First, a 300 mm long carbon steel block was prepared. The surface roughness Rz of the surface where ultrasonic waves were incident was 18 μm, and the surface where ultrasonic waves were reflected was 1.6 μm. A load was applied by the actuator, and the ultrasonic probe was pressed against the carbon steel block with a pressure of 0.15 MPa. Figure 13 shows the dependence of the reflected wave amplitude on the closest distance between holes (normalized by wavelength λ). For smooth movement of the probe, the closest distance between holes formed in the sheet material is preferably 0.1 times the wavelength λ or more. Considering the amplitude of the reflected wave, the closest distance between holes is preferably 1.5 times the wavelength λ or less. After the test, the contact member was heated with a hair dryer. When the temperature reached 120°C, the contact member peeled off from the ultrasonic probe. The contact member was easily replaced.

[0045] (Example 2, Comparative Example 2) A 2 mm thick elastomer sheet of polystyrene-poly(ethylene-butylene)-polystyrene (containing paraffin, sound speed under experimental conditions: 1350 m / s) was prepared. 100 μm diameter holes were drilled all over the surface of polymer sheets of various thicknesses, with a nearest neighbor spacing of 50 μm. The perforated polymer sheet was brought into close contact with an elastomer sheet to form a contact member. An ultrasonic probe was constructed by attaching the above-mentioned elastomer sheet of the contact member to the surface of an ultrasonic transmitting / receiving element with a frequency of 2.25 MHz, via the surface to which the sheet member (polymer sheet) was not attached.

[0046] First, a shear tensile test was conducted to determine whether the probe could be moved under its own weight alone without any additional load. A load cell was connected to the ultrasonic probe, and the probe was placed on a stainless steel plate with a surface roughness Rz of 32 μm. The stainless steel plate was then moved at a low speed to measure the static friction coefficient. As a comparative example, a similar measurement was performed on an elastomer sheet without a sheet member attached. As a result, when no sheet member was attached, the static friction coefficient was extremely large, making it difficult to move the probe. In contrast, when a sheet member was installed, the static friction coefficient was uniformly small, making it possible to move the probe.

[0047] Next, ultrasonic testing was performed. A 300 mm long carbon steel block was prepared. The surface roughness Rz of the surface where the ultrasonic waves were incident was 18 μm, and the surface roughness Rz of the surface where the ultrasonic waves bounced back was 1.6 μm. A load was applied by the actuator, and the ultrasonic probe was pressed against the carbon steel block at a pressure of 0.15 MPa. The results are shown in Figures 14 and 15. Figure 15 shows how the multiple reflected wave amplitude normalized by the reflected wave amplitude defined in Figure 14 changes with the thickness of the sheet member. The multiple reflected wave amplitude normalized by the reflected wave amplitude is preferably 0.5 or less. To achieve such a multiple reflected wave amplitude, it is preferable that the thickness of the sheet member be 0.15 to 0.35 times the wavelength λ in the elastomer.

[0048] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0049] 1... ultrasonic inspection device, 2... ultrasonic probe, 3... transducer, 5... ultrasonic element, 6... receiving plate, 9... contact member, 10... contact medium, 11... hole, 12... sheet member, 13... load application jig, 14... bonding layer, 15... reversible first adhesive layer, 16... polymer layer, 17... second adhesive layer

Claims

1. an ultrasonic probe having a transducer having at least one of a function of transmitting and receiving ultrasonic waves and having an ultrasonic functional surface that functions as at least one of a transmitting surface and a receiving surface of ultrasonic waves; a contact member having a first surface that contacts the sonic functional surface of the sonic probe directly or via an intermediate member, and a second surface opposite to the first surface, the contact member including a couplant containing at least an elastomer, and a sheet member having a plurality of holes and provided so as to contact the second surface of the couplant; a load mechanism that applies a load to the contact member and removes the load, the sheet member has a thickness in the range of 0.15 to 0.35 times the wavelength λ of the sound wave propagating through the contact medium, An ultrasonic inspection device, wherein the sheet member has a plurality of holes arranged so that the closest distance between a first hole and a second hole adjacent to the first hole is in the range of 0.1 to 1.5 times the wavelength λ of the sound wave.

2. 2. The ultrasonic inspection device according to claim 1, wherein the plurality of holes in the sheet member are arranged so that the closest distance between adjacent holes is in the range of 0.1 to 1.5 times the wavelength λ of the ultrasonic wave.

3. 3. The ultrasonic inspection device according to claim 1, wherein the elastomer has a Young's modulus of 0.1 MPa or more and 10 MPa or less.

4. 4. The ultrasonic inspection device according to claim 1, wherein a total area of ​​the plurality of holes in the sheet member is equal to or greater than an area of ​​a portion of the sheet member where the plurality of holes are not formed.

5. 5. The ultrasonic inspection device according to claim 1, wherein the vibrator is an ultrasonic transmitting / receiving vibrator.

6. an ultrasonic probe having a transducer having at least one of a function of transmitting and receiving ultrasonic waves and having an ultrasonic functional surface that functions as at least one of a transmitting surface and a receiving surface of ultrasonic waves; a contact member having a first surface that contacts the sonic functional surface of the sonic probe directly or via an intermediate member, and a second surface opposite to the first surface, the contact member including a couplant containing at least an elastomer, and a sheet member having a plurality of holes and provided so as to contact the second surface of the couplant; a load mechanism that applies a load to the contact member and removes the load, An ultrasonic inspection device, wherein the sheet member has a plurality of holes arranged so that the closest distance between a first hole and a second hole adjacent to the first hole is in the range of 0.1 to 1.5 times the wavelength λ of the ultrasonic waves propagating through the contact medium.

7. 7. The ultrasonic inspection device according to claim 6, wherein the plurality of holes in the sheet member are arranged so that the closest distance between adjacent holes is in the range of 0.1 to 1.5 times the wavelength λ of the ultrasonic wave.

8. 7. The ultrasonic inspection device according to claim 6, wherein the elastomer has a Young's modulus of 0.1 MPa or more and 10 MPa or less.

9. 9. The ultrasonic inspection device according to claim 6, wherein the total area of ​​the plurality of holes in the sheet member is equal to or greater than the area of ​​the portion of the sheet member where the plurality of holes are not formed.

10. 10. The ultrasonic inspection device according to claim 6, wherein the vibrator is an ultrasonic transmitting / receiving vibrator.

11. 11. The ultrasonic inspection device according to claim 1, wherein the elastomer includes at least one selected from the group consisting of polyester-based thermoplastic elastomer, styrene-butadiene rubber, isoprene rubber, butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, isobutylene-isoprene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, silicone rubber, fluororubber, chlorosulfonated polyethylene, acrylic rubber, and epichlorohydrin rubber.

12. The ultrasonic inspection device according to claim 1 , wherein the intermediate member is provided with a bonding layer including a first adhesive layer having reversibility.

13. The ultrasonic inspection device according to claim 12 , wherein the first adhesive layer includes any one of a temperature-sensitive adhesive, a light-irradiation curing agent, a heat-foaming agent, a thermal expansion agent, and a photo-induced structural change agent.

14. The ultrasonic inspection device according to claim 12 or 13, wherein the bonding layer further includes at least one selected from a polymer layer and a second adhesive layer.

15. a step of arranging an acoustic probe having a transducer having at least one of the functions of transmitting and receiving acoustic waves and an acoustic functional surface that functions as at least one of the transmitting surface and receiving surface of acoustic waves, via a contact member that includes a contact medium containing at least an elastomer and that contacts the acoustic functional surface directly or via an intermediate member, and a sheet member that is provided in contact with the contact medium and has a plurality of holes, so that the sheet member comes into contact with the test object; applying a load to the contact member to press the contact medium into contact with the subject through the plurality of holes in the sheet member; and performing a non-destructive inspection of the object to be inspected by the ultrasonic probe while pressing the contact member against the object to be inspected. An ultrasonic inspection method, wherein the sheet member has a plurality of holes arranged so that the closest distance between a first hole and a second hole adjacent to the first hole is in the range of 0.1 to 1.5 times the wavelength λ of the sound wave.

16. 16. The ultrasonic inspection method according to claim 15, wherein the step of performing the inspection comprises transmitting ultrasonic waves used as the sound waves from the ultrasonic probe to the object under inspection and receiving reflected waves from the object under inspection with the ultrasonic probe, thereby performing non-destructive inspection of the object under inspection.

17. further removing the load; a step of releasing the contact state of the contact medium from the test object from which the load has been removed, and moving the ultrasonic probe over the test object while keeping the sheet member in contact with the test object; 17. The ultrasonic inspection method according to claim 15 or 16, comprising:

18. 18. The ultrasonic inspection method according to claim 15, wherein the elastomer has a Young's modulus of 0.1 MPa or more and 10 MPa or less.

19. 19. The ultrasonic inspection method according to claim 15, wherein the total area of ​​the plurality of holes in the sheet member is equal to or greater than the area of ​​the portion of the sheet member where the plurality of holes are not drilled.

20. A contact member used in an ultrasonic probe of an ultrasonic inspection device, The device comprises a couplant containing at least an elastomer, and a sheet member having a plurality of holes and provided so as to be in contact with the couplant, The sheet member is a contact member having a plurality of holes arranged so that the closest distance between a first hole and a second hole adjacent to the first hole is in the range of 0.1 to 1.5 times the wavelength λ of the sound wave.

21. The contact member according to claim 20 , wherein the sheet member has a thickness in the range of 0.15 to 0.35 times the wavelength λ of the sound wave.

22. 22. The contact member according to claim 20, wherein the elastomer has a Young's modulus of 0.1 MPa or more and 10 MPa or less.

23. 23. The contact member according to claim 20, wherein a total area of ​​the plurality of holes in the sheet member is equal to or greater than an area of ​​a portion of the sheet member where the plurality of holes are not formed.

24. 24. The contact member according to claim 20, wherein the elastomer comprises at least one selected from the group consisting of polyester-based thermoplastic elastomer, styrene-butadiene rubber, isoprene rubber, butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, isobutylene-isoprene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, silicone rubber, fluororubber, chlorosulfonated polyethylene, acrylic rubber, and epichlorohydrin rubber.

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