Patent Application
20240219354
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2023-000144, filed on Jan. 4, 2023; the entire contents of which are incorporated herein by reference.
Embodiments disclosed herein relate to a sonic inspection device, a sonic inspection method, and a holder for a sonic inspection device.
A sonic inspection device using the propagation of a sound wave such as an ultrasonic wave and an elastic wave is used for inspecting various members, devices, infrastructures, and so on. An ultrasonic inspection device is also used for medical diagnosis and the like. In the case where a probe for sonic inspection used in such inspection devices, such as a sonic receiver, a sonic transmitter, or a sonic transceiver represented by an ultrasonic probe, an AE (Acoustic Emission) sensor, or the like is installed on an object to be inspected, a liquid or viscous couplant such as glycerin, vaseline, or oil is interposed between the object to be inspected and a sonic function surface, of the probe, that functions as at least one of surfaces for transmitting a sound wave and for receiving a sound wave so that the sound wave is efficiently propagated between the probe for sonic inspection and the object to be inspected. This is because, if air which is greatly different in acoustic impedance from a material forming the probe and a material forming the object to be inspected is present between these materials, it reflects sound, making the propagation of the sound difficult.
The aforesaid couplant efficiently transmits the sound wave such as an ultrasonic wave from the probe to the object to be inspected or from the object to be inspected to the probe and thus is important for increasing test accuracy. However, the processes of applying and removing the liquid or viscous couplant are troublesome. This is a factor to increase the inspection time and man-hours. Some objects to be inspected may be contaminated by the couplant, and in this case, the inspection itself cannot be conducted.
A solid couplant has also been proposed, but it is far inferior in ultrasonic propagation to the liquid couplant. A solid couplant having tackiness has also been proposed to avoid the presence of air between an installation surface of the couplant for sonic inspection and an object to be inspected. In the case where a conventional solid couplant having tackiness is used, however, the installation surface of the couplant for sonic inspection comes into close contact with the object to be inspected, and the couplant for sonic inspection cannot be slid. This necessitates once peeling the probe together with the couplant from the object to be inspected even when its installation position has to be moved only by a small distance, leading to the complication of the inspection process. Another problem is that some holding form of the solid couplant on the probe necessitates a lot of time and trouble for changing the couplants.
A sonic inspection device of an embodiment includes: a sonic probe including a transducer configured to execute at least one of transmission and reception of a sound wave, the sonic probe having a sonic function surface constituting at least one of surfaces for transmitting the sound wave and for receiving the sound wave; a couplant that includes an elastomer and a sheet member containing a polymer and having a plurality of openings, the elastomer having a first surface that comes into contact with the sonic function surface of the sonic probe directly or through an intermediate member and a second surface opposite the first surface, and the sheet member being stacked with the elastomer while in contact with the second surface; a holder that holds the couplant to attach the couplant to the sonic probe and to which the sheet member having the plurality of openings is partly fixed while the sheet member having the plurality of openings is at least partly located at an outermost surface under no load condition or under loaded condition; and a loading mechanism that applies a load to the sonic probe.
A sonic inspection device, a sonic inspection method, and a holder for a sonic inspection device of embodiments will be hereinafter described with reference to the drawings. In the embodiments, substantially the same constituent parts will be denoted by the same reference signs and a description thereof may be partly omitted. The drawings are schematic, and a relation between the thickness and the planar dimension of each part, a thickness ratio among the parts, and so on may be different from actual ones. In the description, a term expressing the up-down direction indicates a relative direction when an inspection surface of an object to be inspected is defined as an upper side, and may differ from an actual direction based on a gravitational acceleration direction.
A sound wave mentioned here is a generic name for all the elastic vibration waves propagated in an elastic body regardless of whether it is gas, liquid, or solid and includes not only sound waves in an audible frequency range but also ultrasonic waves having frequencies higher than the audible frequency range, low-frequency sounds having frequencies lower than the audible frequency range, and so on. The frequency of the sound wave is not limited and includes high frequencies to low frequencies.
In the sonic inspection device 1 of the embodiment, the sonic probe 2 has a transceiving surface, a receiving surface, a transmitting surface, and so on for a sound wave. Here, a surface constituting at least one of the sound wave transmitting surface and receiving surface of the sonic probe will be called a sonic function surface. The sonic probe 2 having such a sonic function surface is an ultrasonic probe as an ultrasonic transceiver, for instance. The ultrasonic probe 2 includes an ultrasonic transceiving element 3 having a transducer (piezoelectric body) for ultrasonic flaw detection and electrodes provided on the upper and lower surfaces of the transducer. The angle ultrasonic transceiving element 3 is disposed on a shoe 4 having a predetermined angle and, in this state, is housed in a case 5. The ultrasonic transceiving element 3 is disposed on a wave receiving plate as required. A sound absorbing material 6 is provided on the rear side of the shoe 4. The not-illustrated electrodes of the ultrasonic transceiving element 3 are electrically connected to a connector 7 provided on the case 5. The constituent materials, structures, and so on of the transducer, the ultrasonic transceiving element 3, the shoe 4, the wave receiving plate, and so on may be those in known ultrasonic probes and are not limited.
In the case where the sonic probe 2 is a sonic receiver such as an AE sensor, the same configuration as that of the ultrasonic probe 2 is employed except that a sonic receiving element having a transducer (piezoelectric body) for AE reception is used. In this case, the constituent materials, structures, and so on of the transducer for AE reception, the sonic receiving element, the wave receiving plate, and so on may be those of known transducers for AE reception.
In the sonic inspection device 1 of the embodiment, in the case where the sonic probe 2 is an ultrasonic probe having at least one of the functions of transmitting and receiving a sound wave, it may have the shoe 4 made of a polymeric material or an intermediate member called a retarder. As illustrated in
The couplant 10 including the elastomer 8 and the sheet member 9 having the openings is held by a holder 11 and in this state, is attached to the sonic probe 2. The couplant 10 is partly fixed to the holder 11. The sheet member 9 having the openings is partly bonded and fixed to the holder 11 through an adhesive sheet 12. The sonic inspection device 1 is placed on the object X to be inspected with the couplant 10 in contact with the object X to be inspected. The sonic inspection device 1 is, for example, of a pulse-echo type and measures a sound wave coming from the object X to be inspected to perform a nondestructive inspection of a flaw or the like in the object X to be inspected. The couplant 10 includes the elastomer 8 and the sheet member 9 containing the polymer and having the openings. The sheet member 9 is provided on a contact surface where the elastomer 8 is to come into contact with the object to be inspected.
When the sonic inspection device 1 is used, the holder 11 holding the couplant 10 is mounted on the sonic probe 2. In the sonic inspection device 1 illustrated in
The sonic probe 2 may be in a state of being only inserted in the pressing part 16 and the opening part 14 when used, or when it is used, the holder 11 may be fixed to and integrated with the sonic probe 2 using mechanisms such as plungers 17 as illustrated in
The holder 11 illustrated in
The elastomer 8 is in close contact with the sonic function surface of the sonic probe 2, and as illustrated in
When the sonic inspection is conducted, a load applying device 18 applies a load P to the sonic probe 2. As a result, the load P is applied to the elastomer 8 in contact with the sonic function surface of the sonic probe 2. As illustrated in
The load applying device 18 is an actuator of a mechanical type, a hydraulic type, a pneumatic type, an electromagnetic type, or the like. The load applying device 18 is installed on the sonic probe 2 and is configured to apply the load directly to the sonic probe 2 to thereby apply the load to the couplant 10 through the sonic probe 2. The mechanism 18 for applying the load to the sonic probe 2 and the couplant 10 may be any as long as it is capable of switching between the state of applying the load to the couplant 10 and the state where the load is removed, and its load applying method, the shape of its load applying member, and so on are not limited to specific ones. When the load applied by the load applying device 18 is removed, the deformation of the elastomer 8 caused by the load is alleviated, so that the sheet member 9 having the openings changes to be mainly present on the interface with the object X to be inspected. This makes it possible to easily slide the sonic probe 2 integrated with the couplant 10 and the holder 11, on the object X to be inspected again.
As described above, by fixing part of the couplant 10 including the elastomer 8 and the sheet member 9 containing the polymer and having the openings to the holder 11, it is possible to efficiently propagate the sound wave between the couplant 10 and the object X to be inspected when the load is applied, and to move the sonic probe 2 integrated with the couplant 10 and the holder 11 on the object X to be inspected when the load is removed. Because of these, the nondestructive inspection by the sonic inspection device 1 and the movability of the sonic inspection device 1 are both achieved. Here, the holder 11 may be a resin member, a metal member, or the like formed with a 3D printer or the like, and may be a member formed of any of various materials, such as a member worked from wood, resin, metal, glass, or a composite material of these.
A measured value of the frictional force of the elastomer forming the elastomer 8 is overwhelmingly larger than those of other materials. It is inferred that this large frictional force comes from the phenomenon that is observed as a result of a great increase in its contact area when the elastomer deforms. Even if hard materials such as metals are tried to be brought into contact with each other, only tips of uneven parts of the contact surfaces, specifically, tips of minute projections which occupy only a minute part of the contact surfaces, come into contact. On the other hand, a material with a low modulus of elasticity such as the elastomer comes to have a large contact area even under the same load, and thus its adsorption force increases owing to the large contact area. Further, the viscoelasticity of the elastomer acts to increase the force of peeling off the adsorption interface with which it is in contact, which will be a factor to increase the coefficient of friction. Being thus large in practical (microscopic) contact area with the object X to be inspected, the elastomer can transmit an ultrasonic wave well. However, one that more easily transmits the ultrasonic wave has a larger frictional force and thus is more difficult to peel off.
Therefore, in the couplant 10 and the holder 11 illustrated in
In the sheet member 9 containing the polymer and having the openings, in the case where the sheet member 9 is a mesh sheet, the diameter of yarns forming the bulges, that is, forming the mesh, is preferably not less than 10 μm nor more than 500 μm. In the case where the sheet member 9 is a sheet in which the openings are formed, the distance between the openings is preferably not less than 10 μm nor more than 500 μm. This was found out from the measurement of sound propagation performance under loaded condition and a coefficient of friction with the object X to be inspected under no load condition. If the sheet member 9 having the openings departs from this range, sonic propagation performance tends to decrease or lubricity on the object X to be inspected tends to be worse. The width between the bulges, that is, the major axis of each aperture of the mesh sheet or each opening of the sheet in which the openings are formed is preferably not less than 10 μm nor more than 2000 μm. If the minimum width between the bulges, that is, the minimum major axis of the apertures of the sheet or the openings of the sheet in which the openings are formed is over 2000 μm, in both cases, it may not be possible to sufficiently obtain the effect of reducing the frictional force ascribable to the contact of only the bulges with the object X to be inspected under no load condition. If the width between the bulges, that is, the minimum width of the apertures of the mesh or the major axis of the opening of the sheet is less than 10 μm, it may not be possible to bring the elastomer 8 into sufficient contact with the object X to be inspected under loaded condition.
Further, in the couplant 10 including the elastomer 8 and the sheet member 9 containing the polymer and having the openings, portions, of the uneven part, that come into contact with the object X to be inspected are defined as bulges. In a view of the surface having the uneven structure seen from the normal direction, the total area of indents (the area of these portions projected on a plane) is preferably larger than the total area of the bulges (the area of these portions projected to a plane). This can enhance the sonic propagation efficiency between the elastomer 8 and the object X to be inspected. It is preferable to appropriately select the minimum width of the bulges, the minimum width of the indents, the ratio of the total area of the bulges and the total area of the indents, and so on according to the Young's modulus and the acoustic impedance of the material used in the elastomer 8.
The thickness of the elastomer 8 is preferably not less than 10 μm nor more than 10 mm. The appropriate thickness of the elastomer 8 differs depending on the acoustic impedance and the Young's modulus of the material forming the elastomer 8, but especially when the thickness is not less than about 0.2 mm nor more than about 2 mm, sonic propagation performance is high, and it is also possible to increase lubricity on the object X to be inspected. The elastomer contained in the constituent material of the elastomer 8 includes a thermosetting elastomer and a thermoplastic elastomer, and either of these is usable in the elastomer 8 of the embodiment. The thermoplastic elastomer is a copolymer of two kinds or more of polymers whose moduli of elasticity are different in temperature dependence, for instance. Since the elastomer used in the embodiment has a certain level of viscoelasticity and can stick to a target, it contaminates the surroundings less than other couplants such as water and oil, and being solid, it can be removed easily and is reusable. Since the elastomer 8 expels the air layer when pressed, the elastic constant (Young's modulus) of the used elastomer is preferably not less than 0.1 MPa nor more than 0.1 GPa. Its yield stress which is a stress at which the plastic deformation of a material starts is preferably large, and is preferably 2 MPa or more, and more preferably 20 MPa or more. Its tensile strength is also preferably large and is preferably 2 MPa or more.
Examples of the thermoplastic elastomer mainly forming the elastomer 8 include a polystyrene-based thermoplastic elastomer (SBC, TPS), a polyolefin-based thermoplastic elastomer (TPO), a vinyl chloride-based thermoplastic elastomer (TPVC), a polyurethane-based thermoplastic elastomer (TPU), a polyester-based thermoplastic elastomer (TPEE, TPC), and a polyamide-based thermoplastic elastomer. Examples of the thermosetting elastomer include: styrene-butadiene rubber (SBR), isoprene rubber (IR), butadiene rubber (BR), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR) which are classified as diene rubber; butyl rubber such as isobutylene-isoprene rubber (IIR), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), urethane rubber (U), silicone rubber, and fluorine rubber (FKM) which are classified as non-diene rubber; and other rubber such as chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM), acrylic rubber (ACM), polysulfide rubber (T), and epichlorohydrin rubber (CO, ECO). Since these materials have different properties such as heat resistance, abrasion resistance, oil resistance, chemical resistance, and so on, it is preferable to select an appropriate material for each object to be inspected. Depending on the use, a mixture of a plurality of elastomers may be used. An additive having a size not preventing the transmission of a sound wave, specifically, having a diameter of approximately 200 μm or less may be mixed.
While no load is applied, the member 9 containing the polymer and having the openings can be slid on the object X to be inspected owing to the bulges of the uneven structure of the sheet member 9 having the openings. This is because the material forming the sheet member 9 having the openings is harder than the material forming the elastomer 8, and its bulges have a shape with a small contact area with the object X to be inspected. The sheet member 9 having the openings, in which the bulges are formed, is often made of mainly a polymer material. As the polymer material, a polymer higher in modulus of elasticity than the elastomer mainly forming the elastomer 8 is used. Examples thereof include polyester, polyethylene, polypropylene, nylon, fluororesins such as trifluoroethylene chloride, tetrafluoroethylene, a tetrafluoroethylene-hexafluoropropylene copolymer, a tetrafluoroethylene-ethylene copolymer, and vinylidene fluoride, an ABS resin, polystyrene, a methacrylic resin, polycarbonate, polyacetal, polyurethane, polyvinylidene chloride, polyethylene terephthalate, liquid crystal, and polyvinyl chloride. Any of various kinds of polymer meshes to which metal or the like is sputtered may also be used. One containing other materials such as metal, ceramic, and oxide may be used.
In the case where the sheet member 9 containing the polymer and having the openings, which is included in the couplant 10, is a mesh sheet, the mesh sheet is not limited to what is called a plain weave one formed of warp yarns and weft yarns alternately crossing over each other. It may be a twill weave one formed of warp yarns and weft yarns with the weft yarns each crossing over every two warp yarns, or may be a satin weave one. Further, one in which warp yarns and weft yarns are not orthogonally knitted, and for example, one in which the warp yarns are inclined by about 20 degrees may be used. Further, one in which mesh intersections are fused is desirable because it increases the strength of the sheet member 9 having the openings. Moreover, when such a sheet member 9 is combined with the elastomer 8 to form the couplant 10, the sonic propagation performance sometimes becomes high.
A holder 11 illustrated in
In
The holder 11 illustrated in
As illustrated in
In the sonic inspection device 1 illustrated in
As illustrated in
As illustrated in
In the sonic inspection device 1 illustrated in
Further, as illustrated in
As illustrated in
The sonic probe 2, the couplant 10, the holder 11, and so on in the first embodiment and the sonic probe 2, the couplant 10, the holder 11, and so on in the second embodiment may be variously combined for use. Any of various combinations is applicable, for example, the normal sonic probe 2 may be applied to the sonic inspection device 1 illustrated in
Hereinafter, examples and their evaluation results will be described.
As shown in Table 1 and Table 2, combinations of various couplants and holders were prepared, and performance evaluation was conducted using normal probes or angle probes with a 2.0 MHz frequency. “Shoe material of probe” in Table 1 and Table 2 is a material of a shoe in the case of the angle probe and a material of a retarder in the case of the normal probe. The items entered in Table 1 and Table 2 will be described. “Holder” is intended to mount a combination of an elastomer sheet and a mesh sheet member on a probe, and “With or without holder” indicates whether or not the holder is used in the test. As “Holder structure”, those illustrated in
First, the moving properties of ultrasonic inspection devices were evaluated. A shear tensile test was first conducted to examine whether or not the ultrasonic inspection devices (ultrasonic probes) with only their weight could be moved in the state in which a further load was not applied. The ultrasonic probes were each connected to a load cell, placed on a stainless plate with an 18 μm surface roughness Rz, and moved on the stainless plate at a low speed, and coefficients of static friction were measured. As comparative examples, the measurement was also conducted in the case where the holder was not used and in the case where the mesh sheet member was not fixed to the holder. As a result, in the case where the holder was not used and in the case where the mesh sheet member was not fixed to the holder, the coefficients of static friction were larger than those in the case where the mesh sheet member was fixed to the holder. In all the cases where holders in which various couplants were housed or fixed were used, it was found out that the coefficients of static frictions were small and the ultrasonic probes could be moved. In the cases where the holders illustrated in
Next, an ultrasonic flaw detection test was conducted. A carbon steel block with a 300 mm length was prepared. The surface roughness Rz of a surface on which an ultrasonic wave was incident was 18 μm, and the surface roughness Rz of a surface on which the ultrasonic wave was reflected was 1.6 μm. The flaw detection test was conducted under the condition that an 18 kPa load was applied to the ultrasonic probes by an electromagnetic actuator to press the ultrasonic probes against the carbon steel block. Table 1 shows the test results together with the results of the coefficient of friction. A tendency was recognized that as the aperture ratio of the mesh sheet was larger, the amplitude of an echo waveform was larger and thus was more favorable. Using an elastomer whose Asker C hardness is large results in a small amplitude of the echo waveform, making the ultrasonic flaw detection difficult.
As shown in Table 3, combinations of various couplants and holders were prepared, and performance evaluation was conducted using normal probes or angle probes with a 3.5 MHz frequency. “Shoe material of probe” in Table 3 is a material of a shoe in the case of the angle probe and a material of a retarder in the case of the normal probe. The items entered in Table 3 will be described. “Holder” is intended to mount a combination of an elastomer sheet and a sheet having a plurality of openings on a probe, and “With or without holder” indicates whether or not the holder is used in the test. As “Holder structure”, those illustrated in
First, the moving properties of ultrasonic inspection devices were evaluated. A shear tensile test was first conducted to examine whether or not the ultrasonic inspection devices (ultrasonic probes) with only their weight could be moved in the state in which a further load was not applied. The ultrasonic probes were each connected to a load cell, placed on an aluminum plate with a 35 μm surface roughness Rz, and moved on the aluminum plate at a low speed, and coefficients of static friction were measured. As comparative examples, the measurement was also conducted in the case where the holder was not used and in the case where the sheet member was not fixed to the holder. As a result, in the case where the holder was not used and in the case where the sheet member was not fixed to the holder, the coefficients of static friction were larger than those in the cases where the sheet member was fixed to the holder. In all the cases where holders in which various couplants were housed or fixed were used, it was found out that the coefficients of static friction were small and thus the ultrasonic probes could be moved. Table 3 shows the evaluation results together with the measurement conditions.
Next, an ultrasonic flaw detection test was conducted. A carbon steel block with a 300 mm length was prepared. The surface roughness Rz of a surface on which an ultrasonic wave was incident was 18 μm, and the surface roughness Rz of a surface on which the ultrasonic wave was reflected was 1.6 μm. The flaw detection test was conducted under the condition that an 18 kPa load was applied to the ultrasonic probes by an electromagnetic actuator to press the ultrasonic probes against the carbon steel block. Table 3 shows the test results together with the results of the coefficient of friction. A tendency was recognized that as the inter-bulge distance or the opening diameter of the sheet member was larger, the amplitude of an echo waveform was larger and thus was more favorable.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-000144 | Jan 2023 | JP | national |
