JP5996415B2 - Ultrasonic flaw detection apparatus and method - Google Patents

Description

  Embodiments described herein relate generally to an ultrasonic flaw detection apparatus and method for detecting a defect to be inspected using a nonlinear ultrasonic component.

  The ultrasonic flaw detection test is a technique that enables non-destructive confirmation of the surface and internal soundness of a structural material, and is an inspection technique indispensable in various fields. Particularly in recent years, in order to ensure the safety of plant structures and the like, inspection of places that have not been required so far has been required. Accordingly, not only the reliability of inspection but also the efficiency has been demanded.

  When attempting to accurately size a volume defect existing in a structure, a radiation transmission test (RT) and an ultrasonic flaw test (UT) are effective techniques. The radiation transmission test is effective for detecting defects with a volume such as holes, but is not suitable for detecting defects with no volume such as cracks and delamination. Further, since there are inspection processes such as exposure and development, there is a limit to efficiency.

  On the other hand, the ultrasonic flaw detection test has high applicability to not only holes but also surface defects such as cracks and peeling, and the inspection results can be acquired in real time. In recent years, not only a commonly used monocular probe, but also a plurality of small piezoelectric elements are arranged, and an arbitrary waveform is generated by transmitting an ultrasonic wave by shifting the timing (delay time) for each of these piezoelectric elements. A phased array ultrasonic testing (PAUT) that can be formed has been put into practical use, and the range of application is further expanding. Therefore, it is considered most effective to improve the inspection efficiency based on the ultrasonic flaw detection test.

  Here, increasing the efficiency of inspection means shortening the total inspection time. What contributes to shortening the inspection time is the inspection time per measurement point and the inspection range per measurement point. The inspection time per measurement point depends on the repetition frequency of the flaw detector, the signal processing speed, and the scanning speed of the probe. The flaw detection apparatus generally has a repetition frequency of 1 kHz or more, and the signal processing speed has a speed equivalent to that. The scanning speed of the probe varies widely depending on the object to be inspected and the inspection method, and it is generally difficult to discuss speeding up.

  Here, the inspection range per measurement point contributing to the other efficiency improvement will be described. To the last, the ultrasonic flaw detection test uses a phenomenon such as reflection or diffraction caused by an ultrasonic wave incident on a defect. At this time, it is essential that the incident ultrasonic wave and the signal derived from the defect can be resolved temporally or spatially. This means that a frequency band of the order in which the directivity is maintained and defects can be evaluated using time information is used (the ultrasonic flaw detection test for a general structural material is a band of about 0.5 MHz to 10 MHz. Use).

In this case, the range that can be inspected at a time depends on the probe size. In general, the largest monocular probe or the like has a diameter of 2 inches. Even if the size is simply increased, the resolution is lowered. Therefore, increasing the size beyond that is not practical for ultrasonic flaw detection of structures. The phased array ultrasonic flaw detection test increases the number of sensors, but the inspection range also increases, but the probe volume increases, handling becomes difficult, and the amount of signal processing becomes enormous. This burden increases. Although it is conceivable to increase the area per element of the array probe by increasing the area, it is not practical if the element pitch is increased to half or more of the wavelength, because beam control becomes difficult. As a result, even with a phased array ultrasonic flaw detection test, an area on the order of several thousand mm ² becomes a range that can be inspected at once, and the amount of expansion of the inspection range is naturally limited.

  In addition to the approach of increasing the number of sensors and increasing the sensor diameter, as a method of expanding the inspection range (flaw detection range), a wave having a mode different from the volume wave such as the longitudinal wave and the transverse wave used in the above-described flaw detection is used. Or simply lowering the frequency to expand the reach of the volume wave. A typical example of the former is flaw detection using a guide wave or a surface wave. The flaw detection using the surface wave basically covers only the defects existing on the surface of the inspection object. For this reason, information on the inherent defects and crack depth cannot be obtained. The flaw detection with a guide wave is basically wide from a plate wave such as a Lamb wave to one using a surface wave, but when the object to be inspected is a thick plate, it has no effect on defects existing at a certain depth. .

  If the latter method of reducing the frequency is used, it is possible to propagate ultrasonic waves both on the surface and inside of the inspection object. However, the defect detection sensitivity decreases as the frequency decreases. Therefore, it is possible to increase the displacement amplitude of the ultrasonic wave, to induce an opening / closing behavior or the like in the crack portion, and to generate a nonlinear ultrasonic component (2f, 3f,... Nf, or f / 2, f with respect to the incident frequency f). /3...f/n response). The nonlinear ultrasonic component is a component generated from a defect such as a crack, and may be applicable to highly accurate defect detection and evaluation, material deterioration measurement, and the like.

  For example, Patent Document 1 is a technique for detecting a minute defect at a bonding interface.

JP 2001-305109 A

  However, the technique described in Patent Document 1 is effective only for detecting the presence or absence of defects, and is not used for quantitative evaluation of defect size.

  The embodiment of the present invention has been made in consideration of the above-described circumstances, and can improve the reliability of inspection by quantitatively evaluating the position and size of a defect generated in an inspection target, and can improve the efficiency of inspection. An object of the present invention is to provide an ultrasonic flaw detection apparatus and method that can also be realized.

An ultrasonic flaw detector according to an embodiment of the present invention includes a signal generation mechanism that generates a voltage waveform , and an ultrasonic transmission mechanism that transmits an ultrasonic wave having a frequency of 1 MHz or less and a displacement amplitude of several tens of nanometers or more to an inspection target. An ultrasonic receiving mechanism that receives an ultrasonic echo from the inspection target, an AD conversion mechanism that digitizes the amplified ultrasonic signal to form a digital ultrasonic signal, and an ultrasonic wave in the digital ultrasonic signal An inverse calculation of the echo, a calculation mechanism for obtaining the generation position of the ultrasonic echo as a scattering source spatial distribution, a filtering mechanism for filtering the ultrasonic echo at each position in the scattering source spatial distribution with an arbitrary frequency component, Intensities are extracted for the fundamental wave component and nonlinear ultrasound component of the ultrasonic echoes at each position obtained by the filtering mechanism, and these fundamental wave components and non-linear components are extracted. Intensity extraction mechanism for calculating the generation efficiency of the ultrasonic component, the digital ultrasonic signal, the scattering source spatial distribution, the intensity of the fundamental wave component and the nonlinear ultrasonic component at each position of the scattering source spatial distribution, and these fundamental waves A display mechanism for displaying at least part of the generation efficiency of the component and the nonlinear ultrasonic component, the signal generation mechanism, the ultrasonic transmission mechanism, the ultrasonic reception mechanism, the AD conversion mechanism, the calculation mechanism, the filtering mechanism, And a control mechanism that controls at least one of the intensity extraction mechanism and the display mechanism.

The ultrasonic flaw detection method according to the embodiment of the present invention includes a signal generation step for generating a voltage waveform , and an ultrasonic wave for transmitting an ultrasonic wave having a frequency of 1 MHz or less and a displacement amplitude of several tens of nm or more to an object to be inspected. A transmission step, an ultrasonic reception step for receiving an ultrasonic echo from the object to be inspected, an AD conversion step for digitizing the amplified ultrasonic signal into a digital ultrasonic signal, and the digital ultrasonic signal An inverse calculation of the ultrasonic echo, a calculation step for obtaining the generation position of the ultrasonic echo as a scattering source spatial distribution, and a filtering step for filtering the ultrasonic echo at each position in the scattering source spatial distribution with an arbitrary frequency component And the intensity of the fundamental wave component and the nonlinear ultrasonic component of the ultrasonic echo at each position obtained in the filtering step. An intensity extraction step for calculating the generation efficiency of the fundamental wave component and the nonlinear ultrasonic component, and the digital ultrasonic signal, the scattering source spatial distribution, the fundamental wave component and the nonlinear supersonic wave at each position in the scattering source spatial distribution. And a display step for displaying at least part of the intensity of the sound wave component and the generation efficiency of these fundamental wave component and nonlinear ultrasonic wave component.

  According to the embodiment of the present invention, it is possible to improve the reliability of inspection by quantitatively evaluating the position and size of the defect generated in the inspection target, and also realize the efficiency of the inspection.

1 is a configuration diagram showing a first embodiment of an ultrasonic flaw detector according to the present invention. FIG. The perspective view which shows notionally the shape echo and defect echo which generate | occur | produce from the to-be-inspected object of FIG. The block diagram of the ultrasonic flaw detector which shows the case where the ultrasonic transmission mechanism of FIG. 1 is a laser ultrasonic transmission mechanism. The block diagram of the ultrasonic flaw detector which shows the case where the ultrasonic receiving mechanism of FIG. 1 is a laser interferometer or a laser vibrometer. FIGS. 1A to 1C show propagation forms of ultrasonic waves in the object to be inspected. FIG. 5A is an explanatory view showing a case where the incident ultrasonic waves are high frequency, and FIG. Explanatory drawing explaining the opening / closing behavior phenomenon of the defect in the to-be-inspected object of FIGS. (A) is an explanatory view for explaining a nonlinear ultrasonic component generated from a defect in the inspection target in FIGS. 1 to 4, and (B) is a result of frequency analysis of mainly harmonic components in FIG. 7 (A). The graph which shows an analysis result, (C) is a graph which shows the analysis result when frequency-analyzing mainly the subharmonic component of FIG. 7 (A). The form of the defect of FIGS. 1-4 is shown, (A) is a perspective view, (B) is a top view. (A) is explanatory drawing which shows the harmonic component of the ultrasonic echo produced from the defect of FIGS. 1-4, and its frequency analysis result, (B) is the ultrasonic echo produced from the defect of FIGS. Explanatory drawing which shows a subharmonic component and its frequency analysis result. The perspective view which shows typically a mode that the output form of a fundamental wave component and a nonlinear ultrasonic component differs in the shape echo and defect echo which arose from the test object of FIGS. The block diagram which shows 2nd Embodiment of the ultrasonic flaw detector based on this invention. The block diagram which shows the case where the ultrasonic transmission mechanism and ultrasonic reception mechanism of FIG. 11 are in a non-contact state with a test object. Explanatory drawing which shows typically a mode that the ultrasonic receiving mechanism of FIG. 12 receives the leaked ultrasonic wave leaked into water from the defect. The block diagram which shows 3rd Embodiment of the ultrasonic flaw detector based on this invention. The block diagram which shows the case where only the ultrasonic transmission mechanism of FIG. 14 is plural. FIG. 15 is a configuration diagram showing a case where there are a plurality of ultrasonic receiving mechanisms in FIG. 14 and each is a laser interferometer or a laser vibrometer. The block diagram which shows an example comprised so that the ultrasonic transmission mechanism and ultrasonic reception mechanism of FIG. 14 might be operated by a scanning mechanism. The block diagram which shows 4th Embodiment of the ultrasonic flaw detector based on this invention. The block diagram which shows the case where the two imaging devices of FIG. 18 are installed. The block diagram which shows the example by which the pattern laser irradiation apparatus was attached to the imaging device of FIG.

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

[A] First embodiment (FIGS. 1 to 10)
FIG. 1 is a block diagram showing a first embodiment of an ultrasonic flaw detector according to the present invention, and FIG. 2 is a perspective view conceptually showing shape echoes and defect echoes generated from an inspection target in FIG. is there. An ultrasonic flaw detection apparatus 10 shown in FIG. 1 transmits low-frequency and large-amplitude ultrasonic waves (incident ultrasonic waves Ui) to the inspection object 1 to detect the inspection object 1 in a wide range and to inspect the inspection object. A non-linear ultrasonic component (harmonic component Uh, subharmonic component Us) generated from one defect D is received to detect the defect D, and includes a signal generation mechanism 11, an applied voltage amplification mechanism 12, and an ultrasonic transmission mechanism. 13, an ultrasonic reception mechanism 14, a reception signal amplification mechanism 15, an AD conversion mechanism 16, a calculation mechanism 17, a filtering mechanism 18, an intensity extraction mechanism 19, a display mechanism 20, and a control mechanism 21.

  The signal generation mechanism 11 executes a signal generation step for generating a voltage waveform, and its control may be in either digital or analog form, and its output is an analog voltage signal. Waveforms that can be generated from the signal generating mechanism 11 include, in addition to basic sine waves, rectangular waves, sawtooth waves, or triangular waves, chirp waves, M-sequence waveforms, or mixing waves composed of a superposition of a plurality of frequencies. Waveforms can also be generated. The wave number of the generated voltage can be transmitted with an arbitrary wave number such as a pulse wave, continuous wave, or burst wave. Or, the output system of the signal generation mechanism 11 is 1 or more.

  The applied voltage amplification mechanism 12 executes an applied voltage amplification step for amplifying the amplitude of the voltage waveform to an arbitrary intensity. Further, by dividing the applied voltage input at that time by a time window, it is possible to partially increase the strength. The signal generating mechanism 11 and the applied voltage amplifying mechanism 12 are not separate as shown in FIG. 1, but may be incorporated in the unit.

  The ultrasonic transmission mechanism 13 transmits a low-frequency and large-amplitude incident ultrasonic wave Ui to the inspection object 1 and executes an ultrasonic transmission step for exciting ultrasonic vibrations over a wide range of the inspection object 1. is there. Here, the incident ultrasonic wave Ui having a low frequency and a large amplitude is an ultrasonic wave having a frequency of 1 MHz or less and a displacement amplitude of several tens of nm or more.

  Further, the ultrasonic transmission mechanism 13 can generate ultrasonic waves by a piezoelectric element that can generate ultrasonic waves by a piezoelectric effect of ceramics, composite material, or other materials, a piezoelectric element by a polymer film, or other than these piezoelectric elements. The structure includes a mechanism and a front plate attached to the ultrasonic oscillation surface. A Langevin vibrator (described later), an actuator having a magnetostriction effect, or the like can also be used as the ultrasonic generation mechanism 14.

  Further, instead of the combination of the signal generating mechanism 11, the applied voltage amplifying mechanism 12, and the ultrasonic transmission mechanism 13, as shown in FIG. A laser ultrasonic transmission mechanism 22 that excites an elastic wave may be used. Examples of the laser used at this time include Nd: YAG laser, CO2 laser, Er: YAG laser, titanium sapphire laser, alexandrite laser, ruby laser, dye (die) laser, and excimer laser. Conceivable.

  The ultrasonic reception mechanism 14 executes an ultrasonic reception step of receiving an ultrasonic echo (a shape echo Uc, which will be described later shown in FIG. 2 and a defect echo Ud shown in FIG. 2) as a reception ultrasonic wave Ur from the object 1 to be inspected. There is no particular limitation as long as it can receive ultrasonic waves. A piezoelectric element that can receive ultrasonic waves due to the piezoelectric effect of ceramics, composite materials, or other materials, a piezoelectric element that uses a polymer film, or a mechanism that can receive ultrasonic waves other than these piezoelectric elements, and an ultrasonic oscillation surface. The front plate is generally called an ultrasonic probe. Further, the ultrasonic receiving mechanism 14 irradiates a test object 1 with a Langevin transducer, an electromagnetic ultrasonic probe, a magnetostrictive sensor, or a laser as shown in FIG. A laser interferometer 23 or a laser vibrometer 24 that observes the Doppler shift may be used. The ultrasonic transmission mechanism 13 and the ultrasonic reception mechanism 14 can be shared by the same element. In that case, a damping material for damping ultrasonic waves is added.

  Here, examples of the laser interferometer 23 include a Michelson interferometer, a homodyne interferometer, a heterodyne interferometer, a Fizeau interferometer, a Mach-Zehnder interferometer, a Fabry-Perot interferometer, a photorefractive interferometer, and the like. A laser interferometer is also conceivable. A knife edge method is also conceivable as a method other than the interference measurement.

  The reception signal amplification mechanism 15 executes a reception signal amplification step for amplifying the ultrasonic signal of the received ultrasonic echo, and is generally called a preamplifier. The reception signal amplification mechanism 15 may be incorporated in another device, for example, the ultrasonic reception mechanism 14 or the AD conversion mechanism 16, or may be configured separately. Further, the AD conversion mechanism 16 performs an AD conversion step in which the ultrasonic signal amplified by the reception signal amplification mechanism 15 is digitized into a digital ultrasonic signal.

  The voltage generated by the signal generation mechanism 11 and the applied voltage amplification mechanism 12 is applied to the ultrasonic transmission mechanism 13, and the ultrasonic transmission mechanism 13 applies low-frequency and large-amplitude incident ultrasonic waves Ui to the inspection target 1. Send. Conventional ultrasonic flaw detection up to sizing has a narrow propagation form as shown in FIG. 5A because a high frequency is used, and the flaw detection range is limited. On the other hand, since the incident ultrasonic wave Ui of the present embodiment has a low frequency, as shown in FIG. 5 (B), the surface of the object 1 to be inspected and its low directivity and low propagation attenuation factor. Propagates throughout the interior. When the incident ultrasonic wave Ui reaches the defect D existing in the inspection object 1, a defect echo Ud (FIG. 2) is generated from the defect D.

  Further, since the incident ultrasonic wave Ui has a large amplitude, as shown in FIG. 6, an opening / closing behavior phenomenon called clapping occurs between the defect interface D1 and the defect interface D2 of the defect D, and the defect interface D1 and the defect interface D2 And hit each other or rub. This phenomenon causes a rectifying effect that transmits only the compression phase of the incident ultrasonic wave Ui and does not transmit the tensile phase. In addition, slippage occurs in the defect interfaces D1 and D2 due to shear components acting on the defect interface D1 and the defect interface D2, or the defect interface D1 vibrates and collides with the defect interface D2, causing the defect interface D2 to vibrate. A phenomenon that causes such behavior is known.

  Due to these rectification effects and slipping phenomenon, as shown in FIG. 7, the harmonic component Uh in which the incident frequency fi of the incident ultrasonic wave Ui is double, triple, quadruple, n times, and the incident frequency fi is 1. A non-linear phenomenon occurs in which a sub-harmonic component Us is generated that is 1/2 times, 1/3 times, 1/4 times, 1 / n times. These nonlinear ultrasonic components are observed by being included in the defect echo Ud together with the fundamental wave component whose frequency is the incident frequency fi. In FIG. 7A, the characteristics of the harmonic component Uh and the subharmonic component Us are shown separately, but they may be generated in combination. The non-linear phenomenon also occurs inside the ultrasonic transmission mechanism 13, the interface between the ultrasonic transmission mechanism 13 and the inspection target 1, an acoustic medium such as water 34 to be described later, and the like.

  This nonlinear phenomenon appears as a change in the intensity of the frequency component when the harmonic component Uh and the subharmonic component Us of the received ultrasonic wave Ur are subjected to frequency analysis (FFT or the like) depending on the presence or absence of the defect D of the inspection object 1. (FIGS. 7B and 7C). As shown in FIGS. 7 and 8, the intensity of this frequency component includes the incident frequency fi and incident wave amplitude Ai of the incident ultrasonic wave Ui, the depth Da, the length Db and the opening width Dd of the defect D, and the periphery of the defect D. It changes depending on the stress Dp. For example, as shown in FIG. 9, in the defect D having a certain length Db, both the second harmonic component 2fi and the fourth harmonic component 4fi can be observed, but in another defect D in which the length Db is halved, A phenomenon occurs such that the intensity of the fourth harmonic component 4fi becomes higher than the intensity of the second harmonic component 2fi.

  On the other hand, since the incident ultrasonic wave Ui having a low frequency and a large amplitude propagates in the inspection object 1 over a wide area, an ultrasonic echo may be obtained from other than the defect D of the inspection object 1. Although it may occur due to a composition change in the welded part or the like, as shown in FIG. 2, most of them are ultrasonic echoes from the bottom surface 2, the edge 3, and the corner part 4 of the inspection object 1. These are collectively referred to as a shape echo Uc. The shape echo Uc needs to be separated from the defect echo Ud when detecting and evaluating the defect D.

  The harmonic component Uh is also detected from the shape echo Uc because it is generated inside the ultrasonic receiving mechanism 14 where the defect D should not exist, in the acoustic medium, and at the contact interface between the ultrasonic receiving mechanism 14 and the inspection object 1. Is done. However, since the harmonic component Uh that appears in the defect echo Ud depends on the defect D, the intensity of the frequency component differs from that of the harmonic component Uh of the shape echo Uc. Further, it is known that the subharmonic component Us is generated only by the interaction between the defect D and the ultrasonic wave.

  The ultrasonic echo (shape echo Uc, defect echo Ud) including the above-described nonlinear ultrasonic components (harmonic component Uh, subharmonic component Us) is received by the ultrasonic receiving mechanism 14 shown in FIG. The ultrasonic signal of the ultrasonic echo is amplified by the reception signal amplification mechanism 15, and the amplified ultrasonic signal is converted into a digital ultrasonic signal by the AD conversion mechanism 16 and output to the calculation mechanism 17.

  The calculation mechanism 17 calculates the inverse problem of the ultrasonic echo in the digital signal from the AD conversion mechanism 16 to obtain the position where the ultrasonic echo (shape echo Uc, defect echo Ud) is generated, and obtains the scattering source spatial distribution. Steps are executed. As a calculation method of the inverse problem calculation, a time-of-flight method or correlation processing can be mentioned, but other signal processing methods may be used. The scattering source spatial distribution obtained by the calculation mechanism 17 is output to the filtering mechanism 18.

  The filtering mechanism 18 filters the ultrasonic echo (shape echo Uc, defect echo Ud) at each position in the scattering source spatial distribution with an arbitrary frequency component, as shown in FIGS. 7B, 7C, and 9. A filtering step for obtaining the intensity of each frequency component by frequency analysis (for example, FFT) is executed, and either analog or digital may be used.

  In the case of digital, it may exist as a circuit, or may be software installed in another device such as the control mechanism 21. Filter types include high pass, low pass, band pass, and band elimination. Transfer functions include Butterworth filters, Bessel filters, Chebyshev filters, simultaneous Chebyshev filters, comb filters, FFT-inverse FFT filters, and other filters.

  The intensity extraction mechanism 19 shown in FIG. 1 has a fundamental wave component and a nonlinear ultrasonic wave component (harmonic) in the ultrasonic echo (shape echo Uc, defect echo Ud) at each position of the inspection object 1 obtained by the filtering mechanism 18. Intensities are extracted for the component Uh and the subharmonic component Us), and an intensity extraction step for calculating the generation efficiency of these fundamental wave components and nonlinear ultrasonic components is executed. Here, the generation efficiency refers to a fundamental wave component (frequency is incident frequency fi) generated in an ultrasonic echo (shape echo Uc, defect echo Ud) and nonlinear ultrasonic component (harmonic component (frequency is 2fi, 3fi, 4fi). ...), the ratio of the intensity to the displacement amplitude of the incident ultrasonic wave Ui with respect to the subharmonic component (frequency is fi / 2, fi / 3, fi / 4 ...).

  The display mechanism 20 is provided at each position of the digital ultrasonic signal obtained by the AD conversion mechanism 16, the scatter source spatial distribution obtained by the calculation mechanism 17, and the scatter source spatial distribution obtained by the filtering mechanism 18. A display step for displaying at least one of the intensities of the fundamental wave component and the nonlinear ultrasonic component and the generation efficiency of the fundamental wave component and the nonlinear ultrasonic component obtained by the intensity extraction mechanism 19 is executed. Further, the display mechanism 20 can also display the incident frequency fi of the incident ultrasonic wave Ui, the measurement conditions, and the like. The display mechanism 20 can also have a function of inputting information directly from the screen, such as a touch panel.

  In FIG. 10, the generation position of the ultrasonic echo in the scattering source space distribution obtained for the inspection object 1 and the intensity of the fundamental wave component and the nonlinear ultrasonic component at each position are displayed. The circled pattern in FIG. 10 indicates the classification of the fundamental wave component (frequency is incident frequency fi) and nonlinear ultrasonic component (frequency is 2fi, 3fi,..., Fi / 2, fi / 3,...). Indicates the magnitude of the intensity of each fundamental wave component and nonlinear ultrasonic component.

  The operator of the ultrasonic flaw detector 10 observes the display content shown in FIG. 10 displayed on the display mechanism 20, for example, so that the intensity of the fundamental wave component (frequency is the incident frequency fi) is high and the harmonic component (frequency) In the case of an ultrasonic echo having a high intensity of 2fi, 3fi), it can be determined that this ultrasonic echo is a shape echo Uc, the intensity of the fundamental wave component (frequency is the incident frequency fi) is small, and a harmonic (frequency) 2fi, 3fi) and an ultrasonic echo having a high intensity of subharmonic (frequency is fi / 2), it can be determined that the ultrasonic echo is a defect echo Ud. As described above, the operator of the ultrasonic flaw detector 10 confirms the difference in intensity or generation efficiency between the fundamental wave component and the nonlinear ultrasonic component in the ultrasonic echo, so that the presence or absence of the defect D, the position of the defect D, and It becomes possible to evaluate the size.

  1 includes a signal generation mechanism 11, an applied voltage amplification mechanism 12, an ultrasonic transmission mechanism 13, an ultrasonic reception mechanism 14, a reception signal amplification mechanism 15, an AD conversion mechanism 16, an arithmetic mechanism 17, and a filtering mechanism 18. And a function of controlling at least one of the intensity extraction mechanism 19 and the display mechanism 20. Further, the control mechanism 21 is provided with a user interface and a display unit for the operator of the ultrasonic flaw detector 10 to control the ultrasonic flaw detector 10, and can easily change a set value and confirm a measurement result. It is configured.

  The control mechanism 21 controls a part or the whole of the ultrasonic flaw detector 10, and among them, the signal generation mechanism 11, the applied voltage amplification mechanism 12, the ultrasonic transmission mechanism 13, the ultrasonic reception mechanism 14, the reception signal amplification. The mechanism 15, the AD conversion mechanism 16, the calculation mechanism 17, the filtering mechanism 18, or the intensity extraction mechanism 19 may be configured to be independently adjusted and driven independently of the control mechanism 21.

  The ultrasonic flaw detector 10 includes a digital ultrasonic signal obtained by the AD conversion mechanism 16, a scatter source spatial distribution obtained by the calculation mechanism 17, and a scatter source spatial distribution obtained by the filtering mechanism 18. Using all or part of the information on the fundamental wave component and nonlinear ultrasonic component intensity at each position and the generation efficiency of the fundamental wave component and nonlinear ultrasonic component obtained by the intensity extraction mechanism 19. 1 may be provided with an identification mechanism 25 (FIG. 1) for executing an identification step for identifying whether the ultrasonic echo generated at each position is a shape echo Uc or a defect echo Ud. In addition to being provided as an individual device, the identification mechanism 25 may be configured to be assembled to the intensity extraction mechanism 19, for example. Identification information obtained by the identification mechanism 25 is also displayed on the display mechanism 20.

With the configuration as described above, the ultrasonic flaw detector 10 of the present embodiment has the following effect (1).
(1) By transmitting a low-frequency ultrasonic wave as the incident ultrasonic wave Ui to the object 1 to be inspected, the ultrasonic wave can be propagated in a wide range and the inspection range can be expanded, and the inspection efficiency can be improved. In addition, by transmitting a large amplitude ultrasonic wave as an incident ultrasonic wave Ui to the inspection object 1, a nonlinear ultrasonic component (harmonic component) is induced by inducing an opening / closing behavior phenomenon or a sliding phenomenon in the defect D of the inspection object 1. Uh, subharmonic component Us) can be generated, and thereby the position and size of the defect D generated in the inspection object 1 can be quantitatively evaluated to improve the reliability of the inspection.

[B] Second Embodiment (FIGS. 11 to 13)
FIG. 11 is a block diagram showing a second embodiment of the ultrasonic flaw detector according to the present invention. Parts similar to those of the first embodiment in the second embodiment are denoted by the same reference numerals, and description thereof is simplified or omitted.

  The ultrasonic flaw detector 30 of the second embodiment is different from the first embodiment in that it is connected to the ultrasonic transmission mechanism 31 and the ultrasonic reception mechanism 32, and the ultrasonic transmission mechanism 31 and the ultrasonic reception mechanism 32. The cable 33 having a waterproof structure is configured to be usable in water 34 as an acoustic medium. Here, the water 34 is not limited to pure water, and may be any liquid that acts as an acoustic medium, such as city water, industrial water, seawater, and oil.

  The waterproof mechanism is formed by covering the cable 33 with a waterproof material, and the ultrasonic transmission mechanism 31 and the ultrasonic reception mechanism 32 are hermetically sealed and a casing is connected to the cable 33 with resin or the like. Or by attaching a cover that covers each of the ultrasonic transmission mechanism 31 and the cable 33, the ultrasonic reception mechanism 32, and the cable 33, but the ultrasonic transmission mechanism 31 and the ultrasonic reception mechanism 32. As long as the voltage application part and the cable 33 are separated from the water 34, a method other than the method described above may be used.

  At this time, since the water 34 becomes an acoustic medium, the ultrasonic transmission mechanism 31 may be installed directly on the inspection object 1 or may take a gap t as shown in FIG. However, the gap t is always required to be filled with water 34 or a medium having similar ultrasonic characteristics.

  The ultrasonic receiving mechanism 32 only needs to be able to perform ultrasonic measurement in water 34, and for example, a hydrophone 35, a laser interferometer 36, or a laser vibrometer 37 may be used. When the laser interferometer 36 or the laser vibrometer 37 is used, the surface of the inspection object 1 may be irradiated with a laser, or a reflector 38 is separately disposed in the water 34 as shown in FIG. Alternatively, the leakage ultrasonic wave Ue leaking into the water 34 may be received and the change in the vibration may be observed. The leakage ultrasonic wave Ue can be received by the hydrophone 35, but in this case, the reflector 38 is unnecessary.

  Since the ultrasonic flaw detector 30 according to the second embodiment has the same configuration as described above, the same effects as the effect (1) of the first embodiment can be obtained, and the following effects (2) and (3) ).

  (2) Since the ultrasonic transmission mechanism 31 and the inspection target 1 are present in the water 34, the incident ultrasonic wave Ui propagates even if the ultrasonic transmission mechanism 31 and the inspection target 1 are not in close contact with each other. is there.

  (3) Since the nonlinear ultrasonic component (harmonic component Uh, subharmonic component Us) generated only from the defect D leaks into the water 34, the nonlinearity locally generated from the defect D in the ultrasonic reception mechanism 32 Ultrasonic components (harmonic component Uh, subharmonic component Us) can be detected. At that time, a wide-band hydrophone 35 can be used, and a non-linear ultrasonic component (a harmonic component Uh, a subharmonic component Us) can be similarly detected by a laser interferometer 36 or the like. At this time, by using the reflector 38 separately installed in the water 34, the laser interferometer 36 or the laser vibrometer 37 can measure the optical path change due to the leaked ultrasonic wave Ue leaking into the water 34 with stable sensitivity. Can do.

[C] Third embodiment (FIGS. 14 to 17)
FIG. 14 is a block diagram showing a third embodiment of the ultrasonic flaw detector according to the present invention. Parts similar to those of the first embodiment in the third embodiment are denoted by the same reference numerals, and description thereof is simplified or omitted.

  The ultrasonic flaw detector 40 of the third embodiment is different from the first embodiment in that one or both of the ultrasonic transmission mechanism 13 and the ultrasonic reception mechanism 14 are plural as shown in FIGS. One or both of the ultrasonic transmission mechanism 13 and the ultrasonic reception mechanism 14 (both in the present embodiment) are configured to be scannable by the scanning mechanism 41.

  When a plurality of ultrasonic transmission mechanisms 13 are provided, a plurality of signal generating mechanisms 11 and applied voltage amplification mechanisms 12 are provided corresponding to these ultrasonic transmission mechanisms 13 or a plurality of ultrasonic transmissions. A voltage waveform is generated for each mechanism 13 (in the case of the signal generation mechanism 11), and the voltage waveform is amplified (in the case of the applied voltage amplification mechanism 12).

  When a plurality of ultrasonic reception mechanisms 14 are provided, a plurality of reception signal amplification mechanisms 15 and AD conversion mechanisms 16 are provided corresponding to these ultrasonic reception mechanisms 14 or a plurality of ultrasonic reception mechanisms 14 are provided. Each ultrasonic wave reception mechanism 14 is configured to amplify an ultrasonic signal (in the case of the reception signal amplification mechanism 15) and digitize it (in the case of the AD conversion mechanism 16). As a method in which each of the single signal generation mechanism 11, the applied voltage amplification mechanism 12, the reception signal amplification mechanism 15, and the AD conversion mechanism 16 corresponds to a plurality of the ultrasonic transmission mechanism 13 and the ultrasonic reception mechanism 14, a plurality of channels are used. A method of switching signals in order by a switch, or a method of using both of them.

  Further, the calculation mechanism 17 is configured to receive an ultrasonic echo (shape echo Uc, defect echo Ud) in the digital signal obtained from each of the plurality of ultrasonic reception mechanisms 14, or scan the ultrasonic mechanism by the scanning mechanism 41. The ultrasonic echoes (shape echo Uc and defect echo Ud) in the digital signal obtained at each of the 14 measurement positions are respectively subjected to inverse problem calculation to identify the ultrasonic generation position and obtain the scattering source spatial distribution.

  The inverse problem calculation in this case uses a time-of-flight method, correlation processing, aperture synthesis processing, or the like. When a plurality of ultrasonic transmission mechanisms 13 and ultrasonic reception mechanisms 14 and the ultrasonic transmission mechanisms 13 and ultrasonic reception mechanisms 14 scanned by the scanning mechanism 41 are in close contact with the surface of the object 1 to be inspected. In addition to the configuration in the water 34 (second embodiment) or the case where the laser interferometer 23 or the laser vibrometer 24 is used, it may be arranged away from the surface of the inspection object 1 (see FIG. 16).

  With the configuration as described above, according to the third embodiment, in addition to the same effect as the effect (1) of the first embodiment, the following effect (4) is obtained.

  (4) Since a plurality of ultrasonic transmission mechanisms 13 and ultrasonic reception mechanisms 14 are provided, ultrasonic signals can be obtained at a plurality of points on the inspection target 1. Alternatively, ultrasonic signals can be obtained at a plurality of points on the inspection object 1 by scanning the ultrasonic transmission mechanism 13 and the ultrasonic reception mechanism 14. Since the calculation mechanism 17 performs inverse problem calculation using the ultrasonic signals obtained at these multiple points, the position where the characteristic signal regarding the presence of the defect D is generated can be reliably specified. Can be identified.

[D] Fourth embodiment (FIGS. 18 to 20)
FIG. 18 is a block diagram showing a fourth embodiment of the ultrasonic flaw detector according to the present invention. In the fourth embodiment, portions similar to those in the first embodiment are denoted by the same reference numerals, and description thereof is simplified or omitted.

  The ultrasonic flaw detection apparatus 50 of the fourth embodiment is different from the first embodiment in that it includes an imaging mechanism 51 that images an ultrasonic flaw detection range in the inspection target 1 simultaneously with the ultrasonic flaw detection. The defect information such as the position of the defect D is displayed so as to be superimposed on the image obtained by the imaging mechanism 51.

  Here, the imaging mechanism 51 may be a general optical camera or a small camera such as an endoscope as long as it can record optical information. The wavelength is not limited to visible light such as infrared rays, ultraviolet rays, and X-rays. The imaging mechanism 51 may be installed independently, but may be integrally connected to the ultrasonic transmission mechanism 13 or the ultrasonic reception mechanism 4 with an arm or the like.

  Furthermore, as shown in FIG. 19, the imaging mechanism 51 may be configured in such a manner that a plurality of, for example, two, are arranged side by side so that a stereo view can be obtained, and a three-dimensional image can be obtained. Further, as shown in FIG. 20, the imaging mechanism 51 is combined with a pattern laser irradiation device 52 that irradiates the surface of the inspection target 1 with a laser pattern, and images the surface of the inspection target 1 irradiated with the laser pattern. By doing so, you may make it easy to recognize the shape (for example, curved surface) of the surface of the test subject 1.

  With the configuration as described above, the fourth embodiment also exhibits the same effect (5) as the effect (1) of the first embodiment, as well as the following effect (5).

  (5) Since the ultrasonic flaw detection result is displayed on the display mechanism 20 so as to be superimposed on the image of the surface of the inspection object 1 obtained by the imaging mechanism 51, the flaw detection result can be displayed more clearly. Further, for example, the surface shape of the object 1 to be inspected is clearly displayed according to the reality by the combination of the stereo imaging by the two imaging mechanisms 51 and the pattern laser irradiation device 52. As a result, the position of the defect D can be specified with high accuracy.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. It is included in the scope and gist of the invention, and is included in the invention described in the claims and the equivalent scope thereof.

DESCRIPTION OF SYMBOLS 1 Inspection object 10 Ultrasonic flaw detector 11 Signal generation mechanism 12 Applied voltage amplification mechanism 13 Ultrasonic transmission mechanism 14 Ultrasonic reception mechanism 15 Received signal amplification mechanism 16 AD conversion mechanism 17 Calculation mechanism 18 Filtering mechanism 19 Strength extraction mechanism 20 Display mechanism 21 Control Mechanism 25 Identification Mechanism 30 Ultrasonic Flaw Detector 31 Ultrasonic Transmitter Mechanism 32 Ultrasonic Receiver Mechanism 33 Cable 34 Water 35 Hydrophone 36 Laser Interferometer 37 Laser Vibrometer 38 Reflector 40 Ultrasonic Flaw Detector 41 Scanning Mechanism 50 Ultrasonic Flaw detector 51 Imaging mechanism D Defect Uc Shape echo Ud Defect echo Uh Harmonic component Us Subharmonic component

Claims (9)

A signal generation mechanism for generating a voltage waveform;
An ultrasonic transmission mechanism for transmitting an ultrasonic wave having a frequency of 1 MHz or less and a displacement amplitude of several tens of nanometers or more to an object to be inspected;
An ultrasonic receiving mechanism for receiving an ultrasonic echo from the test object;
An AD conversion mechanism that digitizes the amplified ultrasonic signal to form a digital ultrasonic signal;
An inverse calculation of the ultrasonic echo in the digital ultrasonic signal, and a calculation mechanism for obtaining the generation position of the ultrasonic echo as a scattering source spatial distribution;
A filtering mechanism for filtering ultrasonic echoes at respective positions in the spatial distribution of the scattering source with arbitrary frequency components;
Intensity extraction mechanism for extracting the intensity of the fundamental wave component and nonlinear ultrasound component of the ultrasonic echo at each position obtained by the filtering mechanism, and calculating the generation efficiency of these fundamental wave component and nonlinear ultrasound component;
The digital ultrasonic signal, the spatial distribution of the scattering source, the intensity of the fundamental wave component and the nonlinear ultrasonic component at each position of the spatial distribution of the scattering source, and at least a part of the generation efficiency of the fundamental wave component and the nonlinear ultrasonic component. A display mechanism to display;
A control mechanism for controlling at least one of the signal generation mechanism, the ultrasonic transmission mechanism, the ultrasonic reception mechanism, the AD conversion mechanism, the calculation mechanism, the filtering mechanism, the intensity extraction mechanism, and the display mechanism. An ultrasonic flaw detector characterized by comprising an ultrasonic flaw detector. Part or all of the digital ultrasonic signal, the scattering source spatial distribution, the intensity of the fundamental wave component and the nonlinear ultrasonic component at each position of the scattering source spatial distribution, and the generation efficiency of the fundamental wave component and the nonlinear ultrasonic component using the information, ultrasound according to claim 1, comprising: the shape echoes due to the shape of the object to be tested, the identification mechanism for identifying the defect echo due to defects of the object to be tested Flaw detection equipment. The ultrasonic wave according to claim 1 or 2 , wherein the ultrasonic transmission mechanism, the ultrasonic reception mechanism, and a cable connected to these mechanisms are configured in a waterproof structure and are usable in water. Flaw detection equipment. A plurality of one or both of the ultrasonic transmission mechanism and the ultrasonic reception mechanism are provided, and the calculation mechanism reverses the ultrasonic echo in the digital ultrasonic signal obtained from each of the plural ultrasonic reception mechanisms. by calculating, the ultrasonic flaw detection apparatus according to any one of claims 1 to 3, characterized in that it is configured to identify the occurrence position of the ultrasonic echo. One or both of the ultrasonic transmission mechanism and the ultrasonic reception mechanism are scanned by a scanning mechanism, and the calculation mechanism reverses the ultrasonic echoes in the digital ultrasonic signal obtained at each measurement position of the ultrasonic reception mechanism. by problems calculation, the ultrasonic flaw detection apparatus according to any one of claims 1 to 3, characterized in that it is configured to identify the occurrence position of the ultrasonic echo. The ultrasonic receiving mechanism is configured by a hydrophone, a laser interferometer, or a laser vibrometer, and is configured to receive leaked ultrasonic waves leaking into the water from a defect to be inspected. The ultrasonic flaw detector according to any one of items 1 to 5 . An imaging mechanism for imaging a flaw detection range by ultrasonic waves in the inspection target is provided, and the display mechanism is configured to display defect information such as a defect position in a superimposed manner on an image obtained by the imaging mechanism. The ultrasonic flaw detector according to any one of claims 1 to 6 . A signal generation step for generating a voltage waveform;
An ultrasonic transmission step of transmitting an ultrasonic wave having a frequency of 1 MHz or less and a displacement amplitude of several tens of nanometers or more to an object to be inspected;
An ultrasonic reception step of receiving an ultrasonic echo from the test object;
An A / D conversion step that digitizes the amplified ultrasonic signal into a digital ultrasonic signal;
An inverse calculation of the ultrasonic echo in the digital ultrasonic signal, and a calculation step of obtaining the generation position of the ultrasonic echo as a scattering source spatial distribution;
A filtering step of filtering ultrasonic echoes at respective positions in the scattering source spatial distribution with arbitrary frequency components;
Intensity extraction step for extracting the intensity of the fundamental wave component and nonlinear ultrasound component of the ultrasonic echo at each position obtained in the filtering step, and calculating the generation efficiency of these fundamental wave component and nonlinear ultrasound component;
At least a part of the digital ultrasonic signal, the scattering source spatial distribution, the intensity of the fundamental wave component and the nonlinear ultrasonic component at each position in the scattering source spatial distribution, and the generation efficiency of the fundamental wave component and the nonlinear ultrasonic component. An ultrasonic flaw detection method comprising: a display step of displaying. Part or all of the digital ultrasonic signal, the scattering source spatial distribution, the intensity of the fundamental wave component and the nonlinear ultrasonic component at each position in the scattering source spatial distribution, and the generation efficiency of the fundamental wave component and the nonlinear ultrasonic component The ultrasonic wave according to claim 8 , further comprising: an identification step for identifying a shape echo caused by a shape of an inspection object and a defect echo caused by a defect of the inspection object using information. Flaw detection method.

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