JP5624250B2 - Lamination peel test method and peel inspection apparatus - Google Patents

Description

  The present invention relates to a laminate peel inspection method and a peel inspection apparatus. In more detail, peeling of a laminated body in which ultrasonic waves are incident from one side of a laminated body in which a plurality of members are laminated and multiple reflected waves are received, and the presence or absence of delamination is inspected by evaluating the received multiple reflected waves. The present invention relates to an inspection method and a peeling inspection apparatus.

  Conventionally, there are many pipes, containers, etc. for the above-mentioned laminate peel inspection as described above. At the time of inspection, humans enter the inside of the pipe, container, etc., and visual inspection, hammering inspection, pinhole inspection, etc. are performed from inside. It was normal. Therefore, at the time of the inspection, the operation has to be stopped, and the inspection takes a lot of time.

  On the other hand, for example, as described in Patent Document 1 as an example of a laminated body, a method for inspecting peeling of a lining without stopping operation has been proposed. In the invention described in the above document, an ultrasonic pulse is incident from the outside of the pipe, the attenuation rate of each reflection echo between the inner circumferential surface of the lining inside the pipe and the pipe body is calculated, and the presence or absence of peeling is investigated. The conventional method does not refer to a lining having a multilayer structure composed of a lining material and an adhesive layer, but when the adhesive layer and the lining material are both peeled from the plate material, the above method is used to estimate the peeling. May be possible.

  However, only the lining material may peel off, and the adhesive layer may remain on the plate material body. However, in the conventional method, the difference between the portion where only the adhesive layer remains and the healthy portion is not clear, and it is difficult to detect the separation of only the lining material.

JP 2000-329751 A

  In view of such a conventional situation, an object of the present invention is to provide a laminate peel inspection method and a peel inspection apparatus capable of clearly detecting delamination of a laminate while being simple.

  In order to achieve the above object, the laminate peel inspection method according to the present invention is characterized in that an ultrasonic wave is incident from a probe disposed on one side of a laminate in which a plurality of members are laminated and multiple reflected waves are received. In the method of inspecting the presence or absence of delamination by evaluating the received multiple reflected waves, the multiple reflected waves are received in advance in the healthy part of the laminate, and the echo height in the healthy part is changed. Obtaining the fluctuation range of the echo height for each number of reflections of the multiple reflected waves including the contact state of the probe with the laminated body and the fluctuation of the surface and interface of the laminated body, and in the simulated peeling portion of the laminated body Multiple reflections including a variation of the contact state of the probe with the laminate and the roughness of the surface and interface of the laminate that receive multiple reflected waves and cause fluctuations in echo height at the simulated peeling portion The fluctuation range of the echo height for each number of reflections is determined, the area where the obtained fluctuation range in the healthy part and the fluctuation range in the simulated peeling part do not overlap is obtained, and the minimum number of reflections in the obtained area is obtained. The number of reflections of the reflected wave that is large and the height of the region is equal to or greater than a predetermined value is obtained, the multiple reflected wave is received in the inspection unit of the laminate, and the reflection that is equal to or greater than the predetermined value previously determined in the inspection unit Inspecting the presence or absence of delamination by comparing the echo height of the reflected wave of the number of wave reflections and the echo height of the reflected wave of the number of reflections of the reflected wave that is equal to or greater than the predetermined value obtained in advance in the healthy part It is in.

  By the way, the echo height (signal intensity) of the reflected wave reflected at the interface of the laminate to be inspected is, for example, the presence or absence of a coating film, its thickness, the contact state of the probe with the flaw detection surface, the flaw detection surface and the interface. It fluctuates depending on factors such as surface roughness and material in the peeled part. Therefore, if attention is paid only to the attenuation factor and attenuation curve of the entire multiple reflected wave, it may be difficult to clearly distinguish the signal from the healthy part and the signal from the separation part due to the fluctuation due to the above factors.

  According to the above configuration, for example, as shown in FIG. 22, the echo height of the reflected wave includes fluctuations (variations) due to the above various factors. Preliminary reception of multiple reflected waves at the sound part of the laminate and fluctuation in echo height at the sound part, contact state of the probe with the laminate, and fluctuation due to roughness of the surface and interface of the laminate The laminated body of the probe that obtains the fluctuation range of the echo height of the multiple reflected waves including the received, receives the multiple reflected waves in the simulated peeling portion of the laminate, and varies the echo height in the simulated peeling portion And the fluctuation range of the echo height of the multiple reflected wave including fluctuation due to the roughness of the surface and interface of the laminate, and the fluctuation range in the healthy part and the fluctuation range in the simulated peeling part overlap. An area that is not to be obtained is obtained, and the number of reflections of the reflected wave that is greater than the minimum number of reflections in the obtained area and the height of the area is a predetermined value or more is obtained. Then, if the echo height of the reflected wave of the healthy part with the number of reflections of the reflected wave equal to or greater than the predetermined value obtained in advance is compared with the echo height of the reflected wave of the inspection part with the same number of reflections, the fluctuation due to the above factors This makes it possible to accurately detect the presence or absence of peeling.

  The range of fluctuation includes fluctuations due to the contact state of the probe with the laminated body and the roughness of the surface and interface of the laminated body. For example, as shown in FIG. 21, the fluctuation range of the echo height of the reflected wave includes fluctuation due to the contact state of the probe. Therefore, if the echo height of the reflected wave of the healthy part with the number of reflections obtained in advance is compared with the echo height of the reflected wave of the inspection part with the same number of reflections, the fluctuation of the echo height due to the contact state of the probe Even if there is variation in the contact state, the presence or absence of peeling can be detected with high accuracy.

  The laminate may include a coating film on the one side, and the variation range may further include a variation due to a film thickness of the coating film. For example, as shown in FIG. 20, the fluctuation range of the echo height of the reflected wave includes a fluctuation due to the film thickness of the coating film. Therefore, if the echo height of the reflected wave of the healthy part with the number of reflections obtained in advance is compared with the echo height of the reflected wave of the inspection part with the same number of reflections, the fluctuation of the echo height due to the coating film thickness is eliminated. Even if the film thickness varies, the presence or absence of peeling can be detected with high accuracy. Furthermore, the fluctuation range may further include fluctuation due to the contents in the peeling portion.

  The propagation time of the reflected wave with the number of reflections of the reflected wave that is equal to or greater than the predetermined value in the healthy part is obtained in advance, and the propagation time of the reflected wave with the number of reflections of the reflected wave that is greater than or equal to the predetermined value in the inspection unit is obtained. The presence or absence of delamination may be inspected by comparing the propagation times. For example, as shown in FIG. 6, in the case where there is separation at the interface between the first member and the second member, the reflected wave is shifted in the propagation time of repeated reflection of the number of reflections of the reflected wave exceeding the predetermined value. Occurs. Therefore, if the propagation time of the reflected wave of the healthy part with the number of reflections obtained in advance is compared with the propagation time of the reflected wave of the inspection part with the same number of reflections, the delamination of the laminate can be detected due to the deviation of the propagation time. It becomes possible. Note that this difference in propagation time does not depend on the frequency of the ultrasonic wave, and the frequency is not particularly limited in principle.

  The plurality of members include at least a first member located on the one side and a second member provided on the first member, and the first member is an acoustic impedance of the second member. The phase of the reflected wave of the number of reflections of the reflected wave that is greater than or equal to the predetermined value in the healthy part is obtained in advance, and the number of reflections of the reflected wave that is greater than or equal to the predetermined value in the inspection unit You may make it test | inspect the presence or absence of the said delamination by calculating | requiring the phase of a reflected wave and comparing these phases.

  According to the above configuration, the first member is made of a material that is smaller than the acoustic impedance of the second member. In such a case, for example, in the case of the laminated body illustrated in FIG. 18A, part of the ultrasonic waves that reach the interface between the first member and the second member is reflected at the interface due to the difference in acoustic impedance. On the other hand, for example, as shown in FIG. 5B, when a peeling portion exists, the ultrasonic wave that reaches the interface is substantially reflected by the peeling portion and does not pass through the first member. Here, the acoustic impedance of the first member is smaller than the acoustic impedance of the second member, and the acoustic impedance of the air constituting the peeling portion is even smaller. Therefore, phase inversion occurs due to the presence of the peeling portion. Therefore, it is possible to detect peeling at the interface by paying attention to the phase inversion between the healthy part and the inspection part.

  The plurality of members include at least a first member located on the one side, a second member provided on the first member, and an adhesive layer that closely contacts these members, You may make it test | inspect the delamination in the interface with the said contact bonding layer. When peeling exists at the interface between the first member and the adhesive layer, for example, as shown in FIG. 6, the echo heights of these reflected waves are greatly different. Therefore, if the echo height of the reflected wave of the healthy part with the number of reflections obtained in advance is compared with the echo height of the reflected wave of the inspection part with the same number of reflections, the separation of the interface at the interface is detected due to the difference in echo height. It becomes possible.

  In such a case, the propagation time of the reflected wave having the number of reflections of the reflected wave that is equal to or greater than the predetermined value in the healthy part is obtained in advance, and the propagation of the reflected wave having the number of reflections of the reflected wave that is equal to or greater than the predetermined value in the inspection unit. It is preferable to inspect the presence or absence of delamination at the interface between the adhesive layer and the second member by obtaining time and comparing these propagation times. When peeling exists at the interface between the second member and the adhesive layer, it has been found that, for example, as shown in FIG. Therefore, if the propagation time of the reflected wave of the healthy part with the number of reflections obtained in advance is compared with the propagation time of the reflected wave of the inspection part with the same number of reflections, it is possible to detect separation at the interface due to the deviation of the propagation time. It becomes.

  The first member may be a steel material, and the second member may be made of a fluororesin lining material. The adhesive layer may be configured with an adhesive and a glass cloth that adheres the fluororesin lining material to the steel material. The laminate is, for example, a liquid container tank.

  Further, the laminate may have a curved surface. In such a case, since the ultrasonic wave is scattered and reflected on the curved surface, it is greatly attenuated. Since attention is paid to the echo height of the reflected wave having the preset number of reflections, the attenuation of the ultrasonic wave according to the curvature of the curved surface is canceled out. Therefore, even if the laminate is a curved surface, a result equivalent to the peel inspection on a flat surface can be obtained.

  The probe may be scanned along the one side, and a scan image may be generated based on the echo height of the reflected wave of the number of reflected waves that is equal to or greater than the predetermined value in the inspection unit. As described above, since the focus is on the reflected wave that has been repeatedly reflected the number of times obtained in advance, a scanned image can be easily generated, and the inspection efficiency is improved.

  When the echo height of the reflected wave of the number of reflections of the reflected wave that is greater than or equal to the predetermined value in the inspection unit is smaller than the echo height of the reflected wave of the number of reflections of the reflected wave that is greater than or equal to the predetermined value in the sound part, It may be determined that corrosion exists in a part of the delamination. When the peeled portion is corroded, the ultrasonic wave is scattered and reflected on the corroded surface, and is greatly attenuated. Therefore, if the echo height of the reflected wave of the healthy part with the number of reflections obtained in advance is compared with the echo height of the reflected wave of the inspection part with the same number of reflections, in addition to the presence or absence of peeling due to the difference in echo height, It becomes possible to detect the presence or absence of corrosion of the part.

  The probe may be a split type probe. By adjusting the focal point to an appropriate distance, the attenuation due to the roughness of the interface can be increased, and the signal from the healthy part and the signal from the corroded part can be more clearly distinguished. In this case, the focal point does not have to be aligned with the interface.

In order to achieve the above-mentioned object, the laminate peel inspection apparatus according to the present invention is characterized by a probe that receives ultrasonic waves from one side of a laminate in which a plurality of members are laminated and receives multiple reflected waves; In a configuration in which a signal processing device that evaluates the received multiple reflected waves is provided and the presence or absence of delamination is inspected by evaluating the received multiple reflected waves, the signal processing device is multiplexed in advance in the sound part of the laminate. For each number of reflections of multiple reflected waves, including the contact state of the probe with respect to the laminate and the fluctuation due to the roughness of the surface and interface of the laminate, which receives the reflected wave and changes the echo height in the healthy part The echo height fluctuation range is obtained, multiple reflected waves are received at the simulated peeling portion of the laminated body, and the probe contacts the laminated body to vary the echo height at the simulated peeling portion And the fluctuation range of the echo height for each number of reflections of the multiple reflected wave including fluctuation due to the roughness of the surface and interface of the laminate, and the obtained fluctuation range in the healthy part and the fluctuation range in the simulated peeling part And the number of reflections of the reflected wave that is larger than the minimum number of reflections in the obtained region and the height of the region is equal to or greater than a predetermined value. And the reflected wave of the number of reflections of the reflected wave that is equal to or greater than the predetermined value obtained in advance in the inspection unit and the number of reflections of the reflected wave that is equal to or greater than the predetermined value obtained in advance in the healthy unit That is, the presence or absence of delamination is inspected by comparing the echo heights.

  The signal processing device may generate a scanned image by multiple reflected waves received by scanning the probe. Examples of the scanned image include a B-scan image and a C-scan image. The probe may be a single-element probe or a two-element probe.

  According to the characteristics of the laminate peel inspection method and peel inspection apparatus according to the present invention, it is possible to clearly detect delamination of the laminate while being simple.

  Other objects, configurations, and effects of the present invention will become apparent from the following embodiments of the present invention.

It is the schematic of the peeling test | inspection apparatus which concerns on this invention. It is a figure for demonstrating the behavior of the ultrasonic wave with respect to each layer of a laminated body, (a) is a healthy part, (b) is peeling in a 1st interface, (c) is a figure which shows peeling in a 2nd interface. is there. It is a graph which shows an example of the RF waveform obtained via the band pass filter in each test body, (a) shows B1 vicinity, (b) shows B10 vicinity, (c) shows B20 vicinity result. (A)-(c) is a graph which shows the detection waveform corresponding to FIG. 3 (a)-(c), respectively. It is a graph explaining the difference of attenuation | damping, (a) is a graph which shows the tendency of attenuation | damping in each test body, (b) is a graph which shows the sensitivity difference of the 1st, 2nd peeling test body with respect to a healthy test body, (c) ) Is a graph showing the attenuation coefficient of each specimen. It is a graph explaining the comparison of the peak time and peak value of a reflected wave. It is the graph which compared the healthy test body, the 1st peeling test body, and the 2nd peeling test body, respectively, (a) is a peak time difference, (b) is a graph which compared echo height. It is a figure which shows an example of another laminated body. FIG. 9 is a view corresponding to FIG. 3 in each test body of the laminate shown in FIG. 8. FIG. 9 is a view corresponding to FIG. 4 in each test body of the laminate shown in FIG. 8. FIG. 9 is a view corresponding to FIG. 5 in each test body of the laminate shown in FIG. 8. FIG. 9 is a view corresponding to FIG. 7 in each test body of the laminate shown in FIG. 8. FIG. 3 is a view corresponding to FIG. 2 according to a second embodiment of the present invention. FIG. 4 is a view corresponding to FIG. 3 according to a second embodiment of the present invention. FIG. 5 is a view corresponding to FIG. 4 according to a second embodiment of the present invention. FIG. 5A is a diagram corresponding to FIG. 5A according to a second embodiment of the present invention. FIG. 7 is a view corresponding to FIG. 6 according to a second embodiment of the present invention. FIG. 9 is a view corresponding to FIG. 2 according to a third embodiment of the present invention. It is a figure which shows the relationship between the film thickness of a coating film, and echo height. It is a figure which shows the fluctuation | variation of the echo height by the variation in the film thickness of a coating film. It is a figure which shows the fluctuation | variation of the echo height by the variation in the contact state of a probe. It is a figure which shows typically the fluctuation | variation of the echo height in a healthy part, a peeling part, and a corrosion part. It is a figure which shows the change of the sound pressure reflectance of a multiple reflected wave. FIG. 23 is a view corresponding to FIG. 22 showing a modified example of the present invention.

  Next, the first embodiment of the present invention will be described in more detail with reference to the accompanying drawings as appropriate.

[Inspection equipment configuration]
As shown in FIG. 1, in the peeling inspection apparatus 1 according to the first embodiment of the present invention, a first member 20 and a second member 30 as a plurality of members are roughly stacked via a thin layer 40. A probe 2 that receives ultrasonic waves from one side 11 (surface 21) of the laminate 10 and receives multiple reflected waves, and a signal processing device 3 that processes and evaluates the received multiple reflected waves are provided. The signal processing device 3 is constituted by a personal computer, for example. Further, a position detector 2 a such as an encoder for detecting a scanning position is attached to the probe 2 and is connected to the signal processing device 3. In the present embodiment, a coating film 50 is formed on one side 11 of the laminate 10 (the surface 21 of the first member 20).

  The signal processing device 3 controls the pulsar 4a to generate ultrasonic pulses from the probe 2. The transmitted ultrasonic pulse passes through (or is transmitted through) the first and second members 20 and 30 and the thin layer 40, is reflected by the interfaces F 1 and F 2, and is received by the probe 2. The received multiple reflected waves are amplified by the receiver 4b and the preamplifier 5, and converted into a digital signal by the A / D converter 7 with the noise removed by the filter 6. Then, signal processing is performed by the signal processing device 3 and displayed on the monitor 8. For example, as shown in FIGS. 3, 4, and 6, the monitor 8 displays a graph in which the horizontal axis is a time axis representing the propagation distance and the vertical axis is the intensity of the reflected wave.

  Further, the signal processing device 3 processes the received signal together with the scanning position data of the probe 2 detected by the position detector 2 a, generates a scanning image such as a B-scan image or a C-scan image, and displays it on the monitor 8. Let Furthermore, the signal processing device 3 further includes warning means 3a that warns of the presence of peeling. In the present embodiment, the warning unit 3a is configured such that when the propagation time in the inspection unit is a predetermined time or more with respect to the propagation time (reference propagation time) in the healthy portion, or the peak value in the inspection portion is the peak value in the healthy portion (reference peak). Warning is given when the value is equal to or greater than a predetermined value. This warning is performed by, for example, a warning sound or a display on the monitor 8.

[Laminate structure]
Here, the laminate 10 to be inspected in the present embodiment is, for example, a wall portion of a liquid container tank that stores liquid. This tank is, for example, a container tank according to the ISO standard. As shown in FIG. 2, the laminate 10 includes a plate material as the first member 20 and a fluororesin lining material as the second member 30 for preventing the plate material 20 from being eroded from the contents. And this fluororesin lining material 30 is adhere | attached on the board | plate material 20 with the contact bonding layer which consists of an adhesive agent as the thin layer 40. FIG.

  In this embodiment, the board | plate material 20 is comprised from the stainless steel plate (SUS board) etc. of thickness 5mm, for example. As the fluororesin lining material 30, for example, a fluororesin lining (PTFE) having a thickness of 3.5 mm is used.

  Further, the adhesive layer 40 in the present embodiment is constituted by an adhesive that adheres a fluororesin lining material 30 (hereinafter simply referred to as “lining material 30”) such as an epoxy resin adhesive to the plate material 20, for example. . The thickness is, for example, 0.1 mm or less, and is sufficiently thin with respect to the plate material 20 and the lining material 30. Here, if the sound velocity of the adhesive layer 40 is 1800 m / s and the frequency of the ultrasonic wave is 5 MHz, the wavelength is 0.36 mm, which is larger than the thickness of the adhesive layer 40. Therefore, the reflected wave from the upper surface 41 of the adhesive layer 40 and the reflected wave from the lower surface 42 cannot be separated, and the signals of the surfaces 41 and 42 cannot be identified by the conventional vertical method. The present invention is advantageous for detection of peeling on the upper and lower surfaces 41 and 42 of the adhesive layer 40 having a thickness shorter (thin) than the wavelength of the ultrasonic wave.

  By the way, the film thickness of the coating film 50 may have an error (variation) of, for example, about 100 to 500 μm depending on the construction state and the secular change. FIG. 19 shows an example of the relative variation of the echo height with respect to the coating film thickness. The vertical axis represents the relative echo height (dB), and the horizontal axis represents the film thickness (μm). In the example of FIG. 19, for example, when the film thickness varies by ± 100 μm with respect to 300 μm, the echo height is ± about 0.9 dB (90% to 111%, M1 in the figure) in the single reflection (B1), 10 times. The reflection (B10) varies ± about 1.1 dB (88% to 114%), and the 20th reflection (B20) varies ± about 1.5 dB (84% to 119%, M2 in the figure). Thus, as the film thickness increases and the number of reflections increases, the echo height varies greatly. For this reason, the signals of the peeled portion and the healthy portion overlap each other, and it may be difficult to distinguish between the two. This figure is an example of an epoxy resin, but is not limited to the material of the coating film, and the echo height varies as described above.

  Moreover, in FIG. 20, the example of the measurement result which changed the film thickness of the coating film 50 by 150-300 micrometers in the healthy peeling body E0 which imitated the healthy part and the simulation peeling body E1 which imitated the peeling part is shown. The vertical axis represents the relative echo height (dB), and the horizontal axis represents the number of reflections. In any specimen, the echo height fluctuates (varies) at each reflection frequency depending on the film thickness. When the number of reflections is 8 or less, the fluctuation range r0 of the healthy part and the fluctuation range r1 of the peeling part overlap, so that it is difficult to distinguish the signals of the healthy part and the peeling part. After the eighth reflection, the difference between the fluctuation ranges r0 and r1 increases as the number of reflections increases.

  Further, the factor that causes fluctuations in the echo height of the reflected wave is not limited to the thickness of the coating film 50. For example, the contact state of the probe 2 with respect to the laminated body 10 is also a factor that varies the echo height. In FIG. 21, the example of the measurement result which varied the contact state of the probe 2 about several different target object (AE) is shown. The vertical axis represents the relative echo height (dB). The average variation with respect to the contact state was ± 2.5 dB. The contact state is a concept including the inclination and pressing force of the probe with respect to the object, the thickness and type of the contact medium, and the like. In addition, as other fluctuation factors, there are the surface of the laminate, the roughness of the interface, the contents in the peeled portion, and the like. As described above, since the multiple reflected wave is affected by various factors, the determination accuracy is lowered in the peeling test based on the attenuation curve and attenuation rate of the entire multiple reflected wave.

  FIG. 22 schematically shows the fluctuation of the echo height including the above fluctuation factors in various test specimens. As described above, the reflected wave signal includes the fluctuation ranges R0 to R2 due to the above various factors. In the healthy specimen E0 and the simulated peel specimen E1, the difference between the fluctuation range R0 of the healthy portion and the fluctuation range R1 of the peel portion increases as the number of reflections increases. This is because the sound pressure reflectance of the air present in the peeled portion is almost 1 and does not change so much. However, since the sound pressure reflectance at the interface is smaller than 1 in the healthy portion, the difference in the sound pressure reflectance repeats the reflection. This is because it is accumulated and becomes larger. Then, the fluctuation due to the above factors is excluded from the difference in the fluctuation range. Therefore, by obtaining the number of reflections with a difference of a predetermined value or more and paying attention to the echo height of the reflected wave with many reflections, the influence of the above fluctuation factors is eliminated, and the signal between the peeled portion and the healthy portion is clarified. It can be distinguished and detection accuracy is improved.

  By the way, the case where corrosion has arisen in the peeling part is also assumed. In such a case, since the ultrasonic waves are scattered on the corroded surface, the more the corrosion progresses (the larger the surface roughness), the greater the attenuation, and the echo height becomes smaller than that of the healthy part. Similarly, the signal of the simulated peeling test body E2 simulating the corroded portion includes the variation due to the above factors. As shown in FIG. 22, the simulated peel test specimen 2 also obtains the number of reflections that have a difference of a predetermined value or more in advance, and pays attention to the echo height of the reflected wave having a large number of reflections, thereby eliminating the influence of the fluctuation factors. In addition to the presence or absence of peeling, the presence or absence of corrosion can be accurately detected. According to the experiments by the inventors, it was possible to detect uneven corrosion of about 1 mm corresponding to a surface roughness Ra (250 μm) ≈Rz1000 (μm).

  Thus, in advance, in the healthy test specimen and the simulated peel test specimen, the number of reflections in which the echo height of the reflected wave is a difference of a predetermined value or more is obtained, and by comparing the echo height of the reflected wave in the number of times, It is possible to inspect the presence / absence of peeling with high accuracy by eliminating the influence of the fluctuation factors. It should be noted that the number of reflections and the predetermined value are not particularly limited as long as various fluctuation factors are eliminated and the signal can be clearly identified. For example, as shown in FIG. 22, the number of reflections may be set to 20 for peeling detection, and the number of reflections may be set to 10 for Z '' greater than a predetermined value Z ′ of 20 for detection of corrosion.

[Behavior of multiple reflected waves]
Here, the relationship between the behavior of ultrasonic waves and the reflected waveform will be described.
FIG. 2A shows the behavior of reflection at a healthy portion where the plate material 20, the lining material 30, and the adhesive layer 40 are in close contact with each other and no separation exists. A part of the ultrasonic wave incident from the upper surface (front surface) 21 (the container outer surface 11) into the plate material 20 from the probe 2 is an interface between the lower surface (back surface 22) of the plate material 20 and the upper surface 41 of the adhesive layer 40. Reflected at the second interface F2 as shown by reference numeral P2.

  On the other hand, the ultrasonic wave transmitted through the second interface F <b> 2 propagates through the adhesive layer 40 and reaches the first interface F <b> 1 that is an interface between the lower surface 42 of the adhesive layer 40 and the upper surface 31 of the lining material 30. Here, when the acoustic impedance between the lining material 30 and the adhesive layer 40 is approximate (the difference in acoustic impedance between the lining material 30 and the adhesive layer 40 is small), the reflection at the first interface F1 hardly occurs. Therefore, the reflected wave indicated by reference sign P1 is hardly received. Therefore, the reception waveform due to the multiple reflection at the healthy part is mainly formed by the reflected wave P2 from the second interface F2.

  FIG. 2B shows the behavior of reflection when peeling occurs at the first interface F1. Since the peeling portion D1 is irrelevant to the reflection of the second interface F2, the peeling portion D1 is reflected at the second interface F2 as indicated by reference numeral P2, similarly to the healthy portion. On the other hand, at the peeling portion D1, an interface between the adhesive layer 40 and the air A is formed. Therefore, unlike the sound part, most of the ultrasonic wave transmitted through the second interface F2 is reflected at the interface between the adhesive layer 40 and the air A as indicated by reference numeral P1 '. Therefore, the reception waveform due to multiple reflection when the peeling portion D1 is present is a waveform obtained by adding the reflected wave P1 'from the peeling portion D1 and the reflected wave P2 from the second interface F2.

  FIG. 2C shows the reflection behavior when peeling occurs at the second interface F2. In the peeling part D2, the interface of the board | plate material 20 and the air A is formed. Therefore, most of the ultrasonic waves reaching the second interface F2 are reflected at the interface between the plate member 20 and the air A as indicated by reference numeral P2 ', and no reflected wave is generated at the first interface F1. Therefore, the reception waveform due to multiple reflection in the presence of the peeling portion D2 is formed substantially by the reflected wave P2 'from the peeling portion D2. Here, the sound pressure reflectance of the air A of the plate member 20 and the peeling portion D2 is almost 1, and it does not change much even if reflection is repeated. On the other hand, the reflected wave P2 of the healthy part is attenuated by reflection at the second interface F2 because the sound pressure reflectance between the plate member 20 and the adhesive layer 40 constituting the second interface F2 is smaller than 1.

  FIG. 23 shows fluctuations in sound pressure reflectance of various materials. The vertical axis represents the relative echo height (dB), and the horizontal axis represents the number of reflections. Although the sound pressure reflectivity varies depending on the material, it is smaller than the sound pressure reflectivity 1 of air, and the difference increases as the number of reflections increases. That is, if the material is smaller than the sound pressure reflectance of air, the presence or absence of peeling can be detected. In the figure, a represents air, b represents water, c represents a fluororesin, d represents a hard rubber, and e represents an epoxy resin, but these are merely examples.

[Difference in received waveform]
Here, the difference of the received waveform in the healthy part, the peeling part D1, and the peeling part D2 will be described with reference to FIGS.
FIG. 3 shows an example of an RF waveform generated by applying a band-pass filter (center frequency 5 MHz) to a signal received by the sound specimen TP0, the first and second peel specimens TP1, TP2. FIG. 4 shows a detection waveform corresponding to FIG. Here, the sound test body TP0 imitated a sound portion in which the plate material 20, the lining material 30, and the adhesive layer 40 were in close contact with each other. The first peel test body TP1 was formed by adhering the plate material 20 and the adhesive layer 40 to simulate the peel portion D1 of the first interface F1. The second peel test body TP2 is composed only of the plate material 20 and simulates the peel portion D2 of the second interface F2. 3 and 4, the vertical axis represents echo height (%), and the horizontal axis represents propagation time (μsec).

  As shown in FIGS. 3 (a) and 4 (a), when the number of reflections is one, the received waveforms almost overlap each other, so that it is difficult to identify the waveforms. On the other hand, as shown in FIGS. 3B and 3C and FIGS. 4B and 4C, as the number of reflections increases, the echo height of each waveform shifts and the overlapping of waveforms is also eliminated. Can be identified. From this, it is difficult to detect peeling at the beginning of observation, but it can be seen that peeling can be detected by using multiple reflected waves.

  Furthermore, the inventors measured the tendency of attenuation in each of the above test specimens. As shown in FIGS. 5A and 5C, it was found that the tendency of attenuation (attenuation coefficient) was larger in the order of the second peel test specimen TP2, the first peel test specimen TP1, and the healthy test specimen TP0. Further, as shown in FIG. 5B, when the attenuation tendency of the healthy specimen TP0 is used as a reference, the sensitivity difference is larger in the second peeling specimen TP2 than in the first peeling specimen TP1, and the damping tendency is larger. I understood that. In FIG. 5A, the vertical axis represents the echo height (dB), and the horizontal axis represents the propagation time (μ seconds). In FIG. 5B, the vertical axis represents the sensitivity difference (dB), and the horizontal axis represents the number of reflections. The vertical axis | shaft of FIG.5 (c) shows an attenuation coefficient (dB / mm).

The mechanism of the above phenomenon is assumed as follows.
The reflected wave P2 of the sound specimen TP0 is attenuated by reflection at the second interface F2 and transmission to the adhesive layer 40. On the other hand, the reflected wave P2 ′ of the second peel test specimen TP2 is less attenuated by reflection than the sound test specimen TP0 because it is reflected by the air A of the peel portion D2. Further, since the second peel test body TP2 does not transmit to the adhesive layer 40, it is not affected by the attenuation by the adhesive layer 40. Therefore, the attenuation of the second peel test specimen TP2 (peeling part D2) is smaller than that of the healthy test specimen TP0. Therefore, the peeling portion D2 can be detected by comparing the peak values (echo heights) of the reflected waves reflected a plurality of times.

  On the other hand, as for the waveform of the first peeling test body TP1, both the reflected wave P1 'from the peeling portion D1 and the reflected wave P2 from the second interface F2 are added. Since the reflected wave P1 ′ of the first peel test specimen TP1 is reflected by the air A of the peel part D1, there is little influence of attenuation due to reflection. As shown in FIG. 5, the attenuation of the first peel test specimen TP1 is a healthy test specimen. Less than TP0. Therefore, when the reflection is repeated a plurality of times, the reflected wave P2 is further attenuated and the reflected wave P1 'becomes relatively large. As a result, the reflected wave P1 'affects the waveform formation, resulting in a waveform that is shifted in time from the waveform of the healthy specimen TP0. This time lag is the thickness of the adhesive layer 40. On the other hand, the waveform of the healthy specimen TP0 is formed by the reflected wave P2 from the second interface F2, and does not include the reflected wave P1 from the first interface F1 corresponding to the reflected wave P1 '. Therefore, the peeling part D1 can be detected by comparing the propagation times of the reflected waves reflected a plurality of times.

  As described above, as a result of the inventors' diligent research, the number of reflections with a difference greater than or equal to a predetermined value is obtained in advance, and by paying attention to the echo height and propagation time of the reflected wave of the number of reflections, It has been found that the influence can be eliminated, the waveform distinguishability (visibility) with respect to the healthy portion can be improved, and the separation at the interfaces F1 and F2 can be detected.

[Peak time and echo height]
Next, detection of peeling at the first and second interfaces F1 and F2 will be described with reference to FIG. In the present embodiment, the propagation time will be described below by taking the peak time of the reflected wave as an example.

  In the case of the peeling portion D1 of the first interface F1, the peak time T1 of the reflected wave that has been reflected a predetermined number of times in the signal waveform S1 is the peak time of the reflected wave that has been repeated the same number of times in the signal waveform S0 of the healthy portion. Appearing later than T0, a time difference ΔT occurs. This is because the attenuation of the healthy part is larger than that of the peeling part D1, and when the reflection is repeated a plurality of times, the reflected wave from the peeling part D1 becomes relatively large, and the waveform is shifted in time with respect to the waveform of the healthy part. Because it becomes. On the other hand, in the case of the peeling portion D2 of the second interface F2, the peak time T2 in the signal waveform S2 is substantially the same as the peak time T0 of the healthy portion. This is because any reflected wave is reflected at the second interface F2.

  Further, in the case of the peeling portion D1 of the first interface F1, the echo height H1 as the peak value of the reflected wave obtained by repeating a predetermined number of reflections in the signal waveform S1 is the same number of reflections in the signal waveform S0 of the healthy portion. Although it is slightly larger than the echo height H0 of the repeated reflected wave, there is no great difference. On the other hand, in the case of the peeling portion D2 of the second interface F2, the echo height H2 in the signal waveform S2 is clearly protruding and large compared to the echo height H0 of the signal waveform S0 of the healthy portion. This is because in the case of the peeled portion D2 of the second interface F2, the attenuation is less because it is hardly reflected and transmitted by the air A having a higher reflectance than the healthy portion.

[Evaluation method]
Thus, it becomes possible to inspect the presence or absence of peeling at the first and second interfaces F1 and F2 by the following peeling inspection method of the laminate.
In advance, the ultrasonic wave is incident from the surface 21 of the plate material 20 and the multiple reflected waves are received at the sound portion and the simulated peeling portion where the plate material 20, the lining material 30 and the adhesive layer 40 are in close contact, and as shown in FIG. The number of reflections of the reflected wave at which the difference between the echo height of the multiple reflected wave and the echo height of the multiple reflected wave at the simulated peeling portion is equal to or greater than a predetermined value is obtained. Then, the peak time and echo height of the reflected wave that has been repeatedly reflected the number of times of reflection are obtained as the reference peak time T0 as the reference propagation time and the reference peak value H0 as the reference echo height. In addition to the peeling, the simulated peeling portion includes a corroded portion in which the peeling portion corrodes.

  Here, in the determination of the number of reflections, for example, a location corresponding to the healthy portion and a location corresponding to the peeling portion are selected in the laminate 10. Further, as described above, the sound test specimen TP0, the first peel test specimen TP1, and the second peel test specimen TP2 can be used, or other devices and other members corresponding to these test specimens can be used. Furthermore, for example, a comparison between a simulated peel test body (contrast test piece) produced by simulating a peeled portion and a location selected as a location corresponding to a healthy portion in the laminate may be used. Thus, since both the “sound part” and the “simulated peeling part” are “parts”, these are “any part of the laminate 10 to be inspected” and “separate from the laminate 10”. Both “test body (piece) and other devices and members corresponding thereto” are included. In addition to the above method, for example, in the case of a laminate having a curvature, a correction value of an echo height corresponding to the curvature may be obtained to correct the sensitivity.

  Next, in a predetermined inspection part E of the plate member 20, the probe 2 is scanned at an appropriate interval along the surface 21 of the plate member 20, and an ultrasonic wave is incident to receive a multiple reflected wave. A peak time T and an echo height H are obtained as a propagation time of a reflected wave that has been reflected the same number of times as the number of reflections obtained in advance in the wave. Then, by comparing these peak times and echo heights, the presence or absence of peeling at the first interface F1 between the lining material 30 and the adhesive layer 40 and the peeling at the second interface F2 between the plate material 20 and the adhesive layer 40 are respectively determined. evaluate.

  Alternatively, a predetermined threshold (time) may be set for the signal processing device 3 in advance with respect to the reference peak time, and the warning means 3a may warn when the peak time exceeds a predetermined gate. Similarly, a predetermined threshold value (amplitude) may be set for the reference peak value, and the warning means 3a may warn when the peak value exceeds a predetermined value. Further, the multiple reflected waves are processed together with the scanning position data of the probe 2 of the position detector 2a, and for example, a scanning image such as a B-scan image or a C-scan image is generated together with a graph as shown in FIG. May be. The presence or absence of peeling may be displayed on these images. In the conventional method of paying attention to the attenuation curve of multiple reflected waves, the multiplexed signal changes as the probe moves, so that it is difficult to distinguish the signals of the healthy part and the peeled part. Further, in the method of analyzing data after scanning, the analysis processing is enormous, and various factors affect the signal, so that the accuracy is also lowered. On the other hand, according to the present invention, since the number of reflections with a difference of a predetermined value or more is obtained in advance and attention is paid to the echo height of the reflected wave of the number of reflections, signal processing can be easily and easily generated.

  Here, in the comparison of the peak time T and the echo height H, the above-mentioned predetermined number of times is the number of times that the peak time T and the echo height H can be compared with respect to the waveform in the healthy part in consideration of the attenuation coefficient. Set. As shown in FIG. 5, the attenuation tendency in the healthy part is different from the attenuation tendency in the case where the peeling part D exists.

  Therefore, for example, in the signal processing device 3, as shown in FIG. 6, the number of times may be set so that the echo height of the reflected wave in the sound part such as a test piece is displayed with an intensity of about 20% of 100% amplitude display. Thereby, each reflected echo from the peeling part of the 1st, 2nd interface F1, F2 in the test | inspection part E becomes distinguishable with respect to a healthy part. As shown in FIGS. 3A and 4A, when the number of reflections is small, a clear difference does not appear in the received signal, and it is difficult to identify the signal (identification of sound or peeling). On the other hand, as shown in FIGS. 3B and 3C and FIGS. 4B and 4C, as the number of reflections increases, it becomes easy to identify whether the sound is healthy or peeled. As the number of reflections increases, the difference in propagation time (distance) of multiple reflected waves increases, the time lag increases, and the signal from the peeled portion of the second interface F2 becomes clear. Further, as shown in FIG. 5A, the difference in attenuation is increased and the difference in echo height is also increased, so that the signal from the peeled portion of the first interface F1 becomes clear. In this embodiment, it is set to about 20 times. Of course, the sensitivity may be adjusted as appropriate.

  The inventors conducted experiments in order to verify the usefulness of the peeling inspection method and the peeling inspection apparatus according to the present invention. Using each of the test specimens described above, multiple reflected waves were received a plurality of times by the single transducer probe 2 having a center frequency of 5 MHz. FIG. 7 shows a graph comparing the results.

  Fig.7 (a) is a graph which shows the peak time difference of each test body on the basis of the thing with the earliest peak time in a healthy part. The vertical axis represents the peak time difference (μ seconds). As is clear from the figure, there is almost no difference in the peak time difference between the healthy specimen TP0 and the second peel specimen TP2. On the other hand, in the first peel test specimen TP1, a clear difference was observed in the peak time difference. Thus, it was found that the presence or absence of peeling at the first interface F1 can be detected by comparing the peak time of the healthy part and the peak time of the inspection part.

  FIG. 7B is a graph comparing the echo height (%) of each specimen. The vertical axis represents the echo height (%). As is apparent from the figure, there is not much difference in echo height between the healthy specimen TP0 and the first peel specimen TP1. On the other hand, in the second peel test specimen TP2, a clear difference appeared in the peak value. Thus, it was found that the presence or absence of peeling at the second interface F2 can be detected by comparing the peak value of the healthy part and the peak value of the inspection part.

  Further, as shown in FIG. 8, the inventors also conducted the above test on a test body in which a fluororesin lining (PFA) was used as the lining material 30 ′ and the adhesive layer 40 ′ was composed of an adhesive 33 and a glass cloth 34. The experiment was conducted in the same manner as in Example 1. As shown in FIGS. 12 (a) and 12 (b), the same results as in Example 1 were obtained, and it was found that detection was possible. 9 to 11 show examples of the RF waveform and the detection waveform and the attenuation coefficient in this test body. The same results as described above were obtained with this lining material 30 '.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the following embodiments, similar members are denoted by the same reference numerals.
In the first embodiment, the laminated body 10 in which the fluororesin lining material 30 (second member) is bonded to the plate material 20 (first member) via the adhesive layer 40 has been described as an example. However, the laminated body 10 as an inspection target is not limited to the one in which the plurality of members 20 and 30 are laminated via the adhesive layer 40. For example, as in the second embodiment shown in FIG. 13, delamination can be detected even in the laminated body 10 ′ in which the first member 20 ′ is directly provided with the second member 30 ′. The first and second members 20 ′ and 30 ′ are not limited to the materials of the first embodiment.

  As shown in FIG. 13, the laminated body 10 ′ in the second embodiment includes a first member 20 ′ that constitutes one side 11 ′ of the laminated body 10 ′ serving as an ultrasonic wave incident position, and the first member. It has a two-layer structure consisting of a second member 30 'provided directly on the other side 22' of 20 '.

  FIG. 13A shows the behavior of reflection at a healthy part where the first member 20 ′ and the second member 30 ′ are in close contact with each other and no separation exists. A part of the ultrasonic wave incident from the upper surface (front surface) 21 ′ to the inside of the first member 20 ′ from the probe 2 and the lower surface (back surface 22 ′) of the first member 20 ′ and the second member 30. The light is reflected as indicated by reference numeral P3 at the interface F3 which is the interface with the “upper surface 31”. The ultrasonic wave transmitted through the interface F3 propagates through the second member 30 ', reaches the lower surface 32' of the second member 30 ', and is reflected as indicated by reference numeral P4. Therefore, the reception waveform due to the multiple reflection at the healthy part is a waveform obtained by adding the reflected wave P3 from the interface F3 and the reflected wave P4 from the lower surface 32 'of the second member 30'.

  On the other hand, FIG. 13 (b) shows the behavior of reflection when peeling occurs at the interface F3. In the peeling portion D3, an interface between the first member 20 'and the air A is formed. Therefore, most of the ultrasonic waves that reach the interface F3 are reflected at the interface between the first member 20 ′ and the air A as indicated by reference numeral P3 ′, and are reflected on the lower surface 32 ′ of the second member 30 ′. Does not occur. Therefore, the reception waveform due to multiple reflection in the presence of the peeling portion D3 is substantially formed by the reflected wave P3 'from the peeling portion D3.

Here, the difference in the received waveform between the healthy part and the peeling part D3 will be described with reference to FIGS.
FIG. 14 shows an example of an RF waveform generated by applying a band-pass filter (center frequency 5 MHz) to signals received by the healthy test specimen TP0 and the third peel test specimen TP3. FIG. 15 shows a detection waveform corresponding to FIG. Here, the healthy test body TP0 imitated a healthy part in which the first member 20 ′ and the second member 30 ′ were in close contact with each other. The third peel test body TP3 is composed of only the first member 20 ′ and simulates the peel portion D3 of the interface F3.

  As shown in FIGS. 14 and 15, also in this embodiment, as the number of reflections increases, the echo height of each waveform shifts and the overlapping of waveforms is eliminated, and the waveform can be identified. From this, it is difficult to detect peeling at the beginning of observation, but it can be seen that peeling can be detected by using multiple reflected waves. Furthermore, as in the first embodiment, when the tendency of attenuation is measured in each of the test specimens, as shown in FIG. 16, the tendency of attenuation (attenuation coefficient) is the third peel test for the healthy specimen TP0. It was found to be larger than the body TP3.

  The reflected wave P3 of the healthy specimen TP0 is attenuated by reflection at the interface F3 and transmission to the second member 30 '. On the other hand, the reflected wave P3 'of the third peel test specimen TP3 is less attenuated by reflection than the sound test specimen TP0 due to reflection by the air A of the peel portion D3. Further, since the third peel test body TP3 does not transmit the second member 30 ', it is not affected by the attenuation by the second member 30'. Therefore, the attenuation of the third peel test specimen TP3 (peeling part D3) is smaller than that of the healthy test specimen TP0. Therefore, it is possible to detect the peeling portion D3 by comparing the peak values of the reflected waves that are reflected in the number of reflections obtained in advance.

  In addition, the waveform of the healthy specimen TP0 is obtained by adding both the reflected wave P3 from the interface F3 and the reflected wave P4 from the lower surface 32 'of the second member 30'. On the other hand, the waveform of the third peel test body TP3 is formed by the reflected wave P3 'from the interface F3, and does not include the reflected wave P4 from the lower surface 32' of the second member 30 '. The reflected wave P3 ′ of the third peel test specimen TP3 is reflected by the air A of the peel part D3, so that the influence of attenuation due to the reflection is small. As shown in FIG. 16, the attenuation of the third peel test specimen TP3 is healthy. Less than TP0. Therefore, when the reflection is repeated a plurality of times, the reflected wave P3 is further attenuated and the reflected wave P4 becomes relatively large. Thereby, the reflected wave P4 affects the waveform formation, and the waveform of the third peel test specimen TP3 becomes a waveform that is shifted (fastened) with respect to the waveform of the healthy test specimen TP0. This time lag is the thickness of the second member 30 '. Therefore, it is possible to detect the peeling portion D3 by comparing the propagation times of the reflected waves reflected after the number of reflections obtained in advance.

Next, detection of peeling at the interface F3 will be described with reference to FIG.
In the case of the peeling portion D3 of the interface F3, the peak time T3 of the reflected wave that has been reflected a predetermined number of times in the signal waveform S3 is the peak time T0 of the reflected wave that has been repeated the same number of times in the signal waveform S0 ′ of the healthy portion. Appears earlier than ', resulting in a time shift ΔT'. This is because the attenuation of the healthy part is larger than that of the peeling part D3, and when the reflection is repeated a plurality of times, the reflected wave from the peeling part D3 becomes relatively large, and the waveform is shifted in time with respect to the waveform of the healthy part. Because it becomes.

  The echo height H3 as the peak value of the reflected wave that has been reflected a predetermined number of times in the signal waveform S3 is the echo height H0 ′ of the reflected wave that has been repeated the same number of times in the signal waveform S0 ′ of the healthy part. Compared to larger. This is because in the case of the peeled portion D3, since the light is reflected and hardly transmitted by the air A having a higher reflectance than the healthy portion, the attenuation is small.

  Thus, also in the laminated body 10 ′ composed of the two members 20 ′ and 30 ′, a difference occurs in the received signal waveforms (reflected waves) of the healthy part and the peeled part as in the first embodiment. Therefore, by detecting the peak times T and / or echo heights H of the reflected waves reflected in the number of reflections obtained in advance, detection of the peeling portion D3 at the interface between the first member 20 ′ and the second member 30 ′ is performed. Is possible.

Finally, the possibilities of yet another embodiment of the present invention will be described.
In the first and second embodiments, the peak time T is used as a comparison target. However, in the third embodiment, the phase of the reflected wave is used together with the peak time T or instead of the peak time T. Specifically, the phase of the reflected wave that has been reflected a predetermined number of times in the healthy portion is obtained in advance as a reference phase. And the phase of the reflected wave which repeated the same number of reflections in an inspection part is calculated | required, and these phases are compared. Here, the adhesive layer 40 is made of a material that is smaller than the acoustic impedance of the second member 30.

  In the case of the healthy part shown in FIG. 18A, a part of the ultrasonic wave incident from the surface 2 (one side 11 of the laminate 10) of the first member 20 from the probe 2 is the same as in the previous embodiment. Reflected at the second interface F2 as indicated by reference numeral P2. The ultrasonic wave transmitted through the second interface F2 is also reflected at the first interface F1 as indicated by reference numeral P1 ″ due to the difference in acoustic impedance between the adhesive layer 40 and the second member 30.

  In the peeling portion D1 of the first interface F1 shown in FIG. 18B, an interface between the adhesive layer 40 and the air A is formed. Therefore, unlike the sound part, most of the ultrasonic wave transmitted through the second interface F2 is reflected at the interface between the adhesive layer 40 and the air A as indicated by reference numeral P1 '.

  Here, the acoustic impedance of air is extremely small and smaller than the acoustic impedance of the adhesive layer 40. Therefore, when the acoustic impedance of the adhesive layer 40 is smaller than the acoustic impedance of the second member 30, the phase is inverted with respect to the signal of the healthy part. That is, since the phase is inverted depending on the presence or absence of the peeling portion D1, it is possible to detect the peeling of the first interface F1 by detecting the presence or absence of the phase inversion. Thus, this embodiment is advantageous when a reflected echo is detected regardless of the presence or absence of peeling at the first interface F1. In the second embodiment as well, when the first member 20 ′ is made of a material that is smaller than the acoustic impedance of the second member 30 ′, the first member 20 ′ and the second member are reversed by phase inversion. It is possible to detect the separation of the interface F3 from 30 ′. In the present embodiment, the signal processing device 3 may be provided with warning means 3a that warns when the phase at the inspection unit is reversed with respect to the healthy part.

  In the first and second embodiments, by comparing both the peak time T and the echo height H of the reflected wave that has been reflected a predetermined number of times, it is possible to detect separation at each interface. However, the peak time T and the echo height H can be compared independently. Furthermore, the phase comparison shown in the third embodiment can be performed alone or in combination with the peak time T and / or the echo height H.

  In the first and second embodiments, the peak time of the reflected wave is used as the propagation time. However, the propagation time is not limited to the peak time, and for example, a rising (falling) time of the reflected wave or a time exceeding (falling) a predetermined amplitude may be used. That is, the propagation time only needs to be a time at which a time lag can be compared (identified) in each waveform of the healthy part and the inspection part.

  In each of the embodiments described above, a single element type probe that also performs transmission and reception is used as the probe 2. However, a dual element probe in which transmission / reception is a separate unit may be used. In the above embodiment, a 5 MHz probe is used as the probe 2. However, the present invention is not limited to this frequency. However, if the frequency is large, the attenuation is large and the signal is small, and if the frequency is small, the waveform cannot be separated. Therefore, the material and thickness of the adhesive layer 40 may be set in consideration.

In general, when the ultrasonic wave exceeds the near field limit distance L expressed by the following equation, the ultrasonic wave spreads at a constant directivity angle α.
Near field limit distance L = (diameter of transducer) squared / (4 × wavelength) (1)
Directional angle α = (70 × wavelength) / (vibrator diameter) (2)
In the present invention, since attention is paid to the reflected wave that has been obtained in advance by the number of reflections, it is preferable that the ultrasonic wave is less attenuated by spreading. For this reason, it is preferable to use a frequency with a short near field limit distance L and a small directivity angle α. Moreover, when detecting a corroded part, since it attenuate | damps largely with the surface roughness of a corroded surface, the frequency which is easy to receive to the influence of surface roughness is preferable. From the above points, it is preferable to use a vertical probe having a vibrator diameter of 20 mm and a frequency of 5 MHz. When detecting a corroded portion, a split probe can be used to increase the influence of attenuation due to the roughness of the corroded surface.

  Moreover, in each said embodiment, although the probe 2 was pressed directly on the surface 21 of the 1st member 20, and the ultrasonic wave was transmitted / received, it is applicable also to a water immersion method.

  In said 1st embodiment, steel materials were used as the 1st member 20 which comprises some laminated bodies 10 to be examined. However, the first member is not limited to a steel material, and may be an ultrasonic transmission material such as another metal, glass, or resin. Moreover, the laminated body 10 to be inspected is not limited to the container tank as in the first embodiment, and may be a constituent part of a pipe in addition to containers such as other tanks and containers. Furthermore, as with the first member, the second member 30 is not particularly limited to a fluororesin as long as it is an ultrasonic transmission material. For example, the second member 30 can be various lining materials such as hard rubber and epoxy resin. Applicable. Of course, it is not limited to lining materials. The same applies to the first and second members 20 (20 ') and 30 (30') in the second and third embodiments. That is, the plurality of members may be any combination of different materials and the same materials.

  In the first and third embodiments, the laminate 10 is laminated with the first and second members 20 and 30 through the adhesive layer 40. However, the number of members to be laminated is not particularly limited, and may be three or more. Further, the adhesive layer 40 only needs to be interposed between at least a part of the plurality of members constituting the laminated body 10, for example, a brazing agent for brazing or one surface layer portion of one adjacent member. It may be an altered part obtained by altering the part. It is possible to detect peeling on the upper and lower surfaces 41 and 42 of the adhesive layer 40. As the material of the adhesive layer 40, a material that approximates the acoustic impedance of a member that is adjacent to the adhesive layer 40 and is located on the side separated from the incident position of the ultrasonic wave can be selected. In the healthy part, if the reflected wave P1 from the interface F1 between the member and the adhesive layer 40 is approximated to be difficult to detect, it is possible to detect the presence or absence of peeling by comparing the propagation time with the healthy part. Because it becomes. On the other hand, it is also possible to select a material whose acoustic impedance is not approximated as the material of the adhesive layer 40 unlike the former. In such a case, a difference is easily generated in the attenuation of the reflected wave at the interface of the adhesive layer 40, and the presence or absence of peeling can be detected by comparing the echo height with the healthy part.

  In each of the above embodiments, the case where air is present in the peeling portion has been described as an example, but it is also possible to detect the case where liquid is present in the peeling portion (corrosion portion). In other words, if there is a difference in sound pressure reflectivity between the sound part and the peeling part having liquid inside, the difference in sound pressure reflectivity results in a difference in the echo height of the reflected wave as the number of reflections increases. It is possible to distinguish between a healthy part and a peeled part. Furthermore, the presence or absence of liquid can also be determined by comparing with the echo height of the simulated peeling portion having air inside. Depending on the member constituting the target interface for detecting peeling (corrosion) and the material of the liquid, it can be detected by the difference in the propagation time of the reflected wave.

  Moreover, in each said embodiment, although demonstrated about the substantially flat flaw detection surface, it is applicable also to the laminated body which has a curved surface. In the case of a curved surface, since ultrasonic waves are scattered and reflected on the surface and interface of the laminate, the attenuation increases as the number of reflections increases. However, if the sound part and the inspection part are both curved surfaces having the same curvature, the influence of the curvature is offset. Therefore, it is possible to detect the presence or absence of peeling in a member having a curved surface such as a pipe.

  In each of the above embodiments, signals of one reflected wave having the number of reflections obtained in advance are compared. However, a plurality of reflected waves may be compared. For example, signals before and after the number of reflections obtained in advance may be compared. Further, the waveform of the received multiple reflected waves may be displayed. In such a case, for example, as shown in FIG. 24, the number of reflections having an echo height equal to the echo height of the healthy part at the number of reflections determined in advance is more than a predetermined number of times Y1, Y2 with respect to the number of reflections determined in advance. If it is, peeling (in the case of Y1) or corrosion (in the case of Y2) may be determined. Even in this case, the number of reflections of the reflected wave in which the difference between the echo height of the multiple reflected wave in the healthy part and the echo height of the multiple reflected wave in the simulated peeling part is equal to or greater than a predetermined value is obtained in advance. Are included in the present invention. In the example of the figure, the horizontal axis is the number of reflections, but it can be replaced with time. The waveform display may be either the entire waveform or a waveform within a predetermined number of times (time).

  In each said embodiment, the laminated body 10 which has the coating film 50 was demonstrated to the example. However, as described above, the variation in the film thickness of the coating film 50 is merely an example of the variation factor of the echo height of the reflected wave. Therefore, the laminated body 10 to be inspected is not limited to the one having the coating film 50, and even the laminated body 10 having no coating film 50 can be similarly inspected.

  INDUSTRIAL APPLICABILITY The present invention is used, for example, as a peeling inspection method and a peeling inspection apparatus for a laminate that inspects peeling at each interface of a thin layer interposed between members in a storage container or piping as a laminate in which a plurality of members are laminated. can do. For example, the present invention can be applied to detection of delamination in a dissimilar material laminate such as adhesion between a CFRP material and aluminum and adhesion between aluminum and copper. Furthermore, it can be applied to brazing of aluminum and steel, brazing of turbine blades and stellite (heat-resistant alloy), soldering of aluminum.

1: peeling inspection device, 2: probe, 2a: position detector, 3: signal processing device, 3a: warning means, 4a: pulser, 4b: receiver, 5: preamplifier, 6: filter, 7: A / D Converter: 8: Monitor, 10: Laminate, 11: One side, 20: First member (plate material), 21: Upper surface, 22: Lower surface, 30: Second member (lining material), 31: Upper surface, 32: Lower surface , 40: thin layer (adhesive layer), 41: upper surface, 42: lower surface, 50: coating film, D1-3: peeled portion, E: inspection portion, F1: first interface, F2: second interface, F3: interface , H, H0-3: Echo height (peak value), P1-P4, P1′-P3 ′: Ultrasound, S0-2, S0 ′: Signal waveform, T, T0-2, T0 ′: Peak time

Claims (16)

A laminate in which ultrasonic waves are incident from a probe arranged on one side of a laminate in which a plurality of members are laminated, multiple reflected waves are received, and the presence of delamination is evaluated by evaluating the received multiple reflected waves. The peeling inspection method of
Preliminary reception of multiple reflected waves at the sound part of the laminate and fluctuation in echo height at the sound part, contact state of the probe with the laminate, and fluctuation due to roughness of the surface and interface of the laminate Obtain the fluctuation range of echo height for each number of reflections of multiple reflected waves including
Fluctuation due to the contact state of the probe with the laminate and the roughness of the surface and interface of the laminate, which receives multiple reflected waves at the simulated exfoliation part of the laminate and changes the echo height in the simulated exfoliation part Obtain the fluctuation range of the echo height for each number of reflections of multiple reflected waves including
Determine the area where the fluctuation range in the determined healthy part and the fluctuation range in the simulated peeling part do not overlap,
Obtain the number of reflections of the reflected wave that is larger than the minimum number of reflections in the obtained area and the height of the area is a predetermined value or more,
The multiple reflection wave is received by the inspection unit of the laminate, and the echo height of the reflected wave of the number of reflections of the reflected wave that is equal to or greater than the predetermined value obtained in advance in the inspection unit and the predetermined value or greater that is obtained in advance in the healthy part The peeling inspection method of the laminated body which test | inspects the presence or absence of the said delamination by comparing the echo height of the reflected wave of the frequency | count of reflection of the reflected wave which becomes. The method according to claim 1, wherein the laminate includes a coating film on the one side, and the variation range further includes a variation due to a film thickness of the coating film. The peeling inspection method for a laminate according to claim 1 or 2, wherein the fluctuation range further includes a fluctuation due to contents in the peeling portion. The propagation time of the reflected wave with the number of reflections of the reflected wave that is equal to or greater than the predetermined value in the healthy part is obtained in advance, and the propagation time of the reflected wave with the number of reflections of the reflected wave that is greater than or equal to the predetermined value in the inspection unit is obtained. The peeling inspection method for a laminate according to any one of claims 1 to 3, wherein the presence or absence of the delamination is inspected by comparing the propagation times. The plurality of members include at least a first member located on the one side and a second member provided on the first member, and the first member is an acoustic impedance of the second member. The phase of the reflected wave of the number of reflections of the reflected wave that is greater than or equal to the predetermined value in the healthy part is obtained in advance, and the number of reflections of the reflected wave that is greater than or equal to the predetermined value in the inspection unit The peeling inspection method for a laminate according to any one of claims 1 to 4, wherein the phase of the reflected wave is obtained and the presence or absence of the delamination is inspected by comparing the phases. The plurality of members include at least a first member located on the one side, a second member provided on the first member, and an adhesive layer that closely contacts these members, The delamination inspection method for a laminate according to claim 1, wherein delamination at the interface with the adhesive layer is inspected. The propagation time of the reflected wave with the number of reflections of the reflected wave that is equal to or greater than the predetermined value in the healthy part is obtained in advance, and the propagation time of the reflected wave with the number of reflections of the reflected wave that is greater than or equal to the predetermined value in the inspection unit is obtained. The peeling inspection method for a laminate according to claim 6, wherein the presence or absence of delamination at the interface between the adhesive layer and the second member is inspected by comparing the propagation times. The laminate peel inspection method according to claim 6 or 7, wherein the first member is a steel material, and the second member is a fluororesin lining material. The laminate peel inspection method according to claim 8, wherein the adhesive layer includes an adhesive that bonds the fluororesin lining material to the steel material and a glass cloth. The method for inspecting a peel-off of a laminate according to claim 8 or 9, wherein the laminate is a liquid container tank. The said laminated body is a peeling test | inspection method of the laminated body in any one of Claims 1-6 which have a curved surface. The scan is performed along the one side of the probe, and a scanned image is generated based on the echo height of the reflected wave of the number of reflections of the reflected wave that is equal to or greater than the predetermined value in the inspection unit. The peeling inspection method for a laminate according to any one of the above. When the echo height of the reflected wave of the number of reflections of the reflected wave that is greater than or equal to the predetermined value in the inspection unit is smaller than the echo height of the reflected wave of the number of reflections of the reflected wave that is greater than or equal to the predetermined value in the sound part, The peeling inspection method for a laminate according to claim 1, wherein it is determined that corrosion is present in a part of the delamination. The method according to claim 13, wherein the probe is a split-type probe. Equipped with a probe that receives ultrasonic waves and receives multiple reflected waves from one side of a stack of multiple members, and a signal processing device that evaluates the received multiple reflected waves, and evaluates the received multiple reflected waves A laminate peeling inspection device for inspecting the presence or absence of delamination by
The signal processing device receives in advance multiple reflected waves in the sound part of the laminate and changes the echo height of the sound part in contact with the laminate and the surface of the laminate And the fluctuation range of the echo height for each number of reflections of multiple reflected waves including fluctuations due to the roughness of the interface,
Fluctuation due to the contact state of the probe with the laminate and the roughness of the surface and interface of the laminate, which receives multiple reflected waves at the simulated exfoliation part of the laminate and changes the echo height in the simulated exfoliation part Obtain the fluctuation range of the echo height for each number of reflections of multiple reflected waves including
Determine the area where the fluctuation range in the determined healthy part and the fluctuation range in the simulated peeling part do not overlap,
Obtain the number of reflections of the reflected wave that is larger than the minimum number of reflections in the obtained area and the height of the area is a predetermined value or more,
The multiple reflection wave is received by the inspection unit of the laminate, and the echo height of the reflected wave of the number of reflections of the reflected wave that is equal to or greater than the predetermined value obtained in advance in the inspection unit and the predetermined value or greater that is obtained in advance in the healthy part A peeling inspection apparatus for a laminate that inspects for the presence or absence of delamination by comparing the echo height of the reflected wave with the number of reflections of the reflected wave. 16. The laminate peeling inspection apparatus according to claim 15, wherein the signal processing device generates a scanned image by using multiple reflected waves received by scanning the probe.

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