JP6581462B2 - Ultrasonic inspection equipment - Google Patents

Description

  The present invention relates to an ultrasonic inspection apparatus and an ultrasonic inspection method.

  As a background art in this technical field, there is JP-A-2001-83125 (Patent Document 1). By superposing piezoelectric materials that vibrate in two orthogonal directions, applying a voltage to these piezoelectric materials to generate vibrations, and superimposing polarized waves orthogonal to the two directions, a super Generate sound waves. A method for measuring acoustic anisotropy of a material having acoustic anisotropy using transverse wave ultrasonic waves having an arbitrary polarization state and a material deterioration diagnostic apparatus using the method for measuring the acoustic anisotropy are described. Yes.

JP 2001-83125 A

  The material described in Patent Document 1 is that material deterioration occurs by simultaneously generating two ultrasonic waves having orthogonal polarizations, measuring acoustic anisotropy, and measuring the transverse wave velocity from the bottom echo and the thickness of the DUT. Although the diagnosis is performed, it does not have a function for determining the extension direction of minute defects or inclusions. In order to determine the extension direction from a reflected wave from a minute defect or an inclusion, it is necessary to collate the recorded value of the ultrasonic reflection signal with a criterion for determining the extension direction. The thing of patent document 1 has a subject in using for the test | inspection which determines the extension direction of a micro defect or an inclusion, etc. by the point that there is no description of a determination standard and its mechanism.

  Therefore, the present invention has been made in view of the above-described problems, and detects minute defects or inclusions present in the inspection target with high accuracy and further determines the extension direction of the minute defects or inclusions. An object of the present invention is to provide an ultrasonic inspection apparatus and an ultrasonic inspection method that can be performed.

  In order to achieve the above object, the present invention provides a first ultrasonic transducer having a first vibration direction, a second ultrasonic transducer having a second vibration direction, and a first ultrasonic transducer having a first vibration direction. A transmitter for controlling a phase difference and an amplitude of a second ultrasonic wave and a second ultrasonic wave having a second vibration direction and transmitting a signal to the first ultrasonic transducer and the second ultrasonic transducer And calculating the first transverse wave ultrasonic wave and the second transverse wave ultrasonic wave from the received waveforms of the first ultrasonic transducer and the second ultrasonic transducer to determine the direction of the reflection target. It has a receiver and a display which displays the judgment result obtained by the receiver.

  According to the present invention, there are provided an ultrasonic inspection apparatus and an ultrasonic inspection method capable of detecting an internal defect or inclusion in a subject with high accuracy and determining the extension direction of a minute defect or inclusion. it can.

1 is a block diagram schematically illustrating an overall configuration of an ultrasonic inspection apparatus according to Embodiment 1. FIG. It is a perspective view of the test | inspection form which concerns on Example 1. FIG. 3 is a flowchart of an operation procedure according to the first embodiment. 1 is a perspective view of a polarization control probe according to Embodiment 1. FIG. FIG. 3 is a block diagram schematically illustrating a waveform generator included in the transmitter according to the first embodiment. 6 is a diagram illustrating an example of a polarization state generated by the polarization control probe according to the first embodiment. FIG. 6 is a graph of an example of a probe output waveform and a synthesized waveform according to Example 1. 6 is a graph of an example of a probe output waveform and a synthesized waveform according to Example 1. FIG. 3 is a block diagram schematically illustrating an arithmetic unit included in the waveform analysis unit according to the first embodiment. 6 is a diagram illustrating an example of a polarization state generated by the polarization control probe according to the first embodiment. FIG. 6 is a diagram illustrating an example of a polarization state generated by the polarization control probe according to the first embodiment. FIG. 6 is a diagram illustrating an example of a polarization state generated by the polarization control probe according to the first embodiment. FIG. FIG. 3 is a diagram schematically illustrating a display of the ultrasonic inspection apparatus according to the first embodiment. FIG. 6 is a diagram schematically illustrating a display of an ultrasonic inspection apparatus according to a second embodiment.

  Ultrasonic flaw detection is used to nondestructively inspect the internal defects or inclusions of a subject. In conventional ultrasonic flaw detection that generates ultrasonic waves (longitudinal wave ultrasonic waves) that travel in a direction perpendicular to the flaw detection surface of the material to be inspected, the reflected waves from the internal defects or inclusions to be inspected are identified. For this reason, the ultrasonic probe is mechanically scanned in the horizontal direction with respect to the subject submerged in water, and the reflected wave signal is imaged to determine the presence or absence of an internal defect or inclusion.

  Therefore, in the ultrasonic flaw inspection using such longitudinal ultrasonic waves, there is a problem that mechanical scanning is required to determine the presence or absence of defects or inclusions, and the inspection time becomes long. In addition, the ultrasonic probe using longitudinal ultrasonic waves generally has the ability to focus a point, the signal intensity of a reflected wave from a defect or an inclusion is reduced, and the S / N ratio of the signal is reduced. There is a problem.

  In order to solve this problem, it is conceivable to use transverse wave ultrasonic waves. The shear wave ultrasonic wave has directivity in the polarization direction, and when it coincides with the extension direction of the defect or inclusion, an improvement in the S / N ratio is expected. If transverse wave ultrasonic waves are used, the sound speed of the transverse wave ultrasonic waves is about half that of the longitudinal wave ultrasonic waves, so it is advantageous to obtain the same measurement accuracy at about half the frequency of the longitudinal wave ultrasonic waves. is there.

  However, in the inspection using the transverse wave ultrasonic wave, in order to make the polarization direction of the transverse wave ultrasonic wave coincide with the extension direction of the defect or the inclusion, it is necessary to scan the rotation direction of the axis perpendicular to the inspection object. A general transverse wave ultrasonic probe performs mechanical scanning while being in contact with an inspection object. In addition, similar to the longitudinal wave ultrasonic immersion test, the transverse wave ultrasonic probe is mechanically scanned in the horizontal direction with respect to the subject, and the reflected wave signal is imaged to indicate the extension direction of the defect or inclusion. Although it can be determined, a certain amount of inspection time is required.

  Patent Document 1 described in the background art describes electronic control of the polarization direction using transverse ultrasonic waves, but does not describe an inspection method for determining the presence or absence of defects or inclusions.

  Hereinafter, an ultrasonic inspection apparatus and an ultrasonic inspection method using the ultrasonic inspection apparatus according to Examples 1 and 2 that are suitable for carrying out the present invention will be described with reference to the drawings. In addition, the following is only an example of implementation, and the content of the invention is not limited to the following specific embodiment. It goes without saying that the present invention can be modified into various modes including the following modes.

  A first embodiment will be described with reference to FIGS.

  The overall configuration of the inspection apparatus according to the present embodiment will be described with reference to FIGS.

  FIG. 1 is a block diagram showing the configuration of a system using a polarization control probe and an ultrasonic flaw detector. FIG. 2 is an explanatory diagram of a measurement mode of defects or inclusions using an ultrasonic flaw detector and a polarization control probe. In FIG. 1 and FIG. 2, the same reference numerals indicate the same parts. However, the example shown in FIG. 2 does not limit the embodiment of the present invention.

  Signals are input to the flaw detector 1 using the input device 2 to the phase difference controller 33, the amplitude controller 3a, and the amplitude controller 3b. A waveform generator 32 provided in the transmitter 3 generates a voltage waveform a and a voltage waveform b based on the phase difference, the amplitude a, and the amplitude b. The voltage waveform at this time may be a pulse wave or a burst wave. However, the pulse width and burst width are set appropriately according to the purpose. Further, the phase difference between the two-directional vibration components of the transverse ultrasonic wave can be specified by, for example, a time difference given to each transmission timing. Here, the input device 2 inputs data to the flaw detection apparatus 1 by operating, for example, a keyboard of a personal computer, a slider displayed on the tablet, and a knob provided on the flaw detection apparatus 1.

  The voltage waveform a and the voltage waveform b are respectively applied to the first piezoelectric element 4a and the second piezoelectric element 4b provided in the polarization control probe 4 and are superimposed on the subject 7 to generate ultrasonic waves. Thereafter, the echo from the subject 7 is received by the polarization control probe 4, and the received waveform 7 a and the received waveform 7 b are input to the receiver 5 provided in the flaw detector 1. Here, the first piezoelectric element 4a or the second piezoelectric element 4b is, for example, a piezoelectric material such as PZT (lead zirconate titanate), and converts an electric signal into vibration, and conversely converts vibration into an electric signal. Is possible.

  Next, the operation procedure of the receiver 5 will be described with reference to the flowcharts of FIGS. The receiver 5 includes a reception waveform transmission path 50 that takes in two reception waveforms acquired by the polarization control probe 4, a calculator 52 that calculates the two reception waveforms, a memory 51, a comparator 53, and a transmitter. 3 includes a control signal generator 54 that generates a phase and amplitude for transmitting a feedback signal, and a defect direction determiner 55. The control signal generator 54 and the defect direction determiner 55 can be implemented by software on a personal computer, for example.

  Using the receiver 5, first, the direction of the main axis where the sound speed is maximum or minimum is measured. In this process, first, in step S101, the polarization control probe 4 is brought into contact with the subject 7 with an appropriate weight. Next, in step S102, appropriate initial values are set for the amplitude 1 and the amplitude 2, and the position at which a specific echo from the subject 7 is generated is input to the flaw detection apparatus 1 by the input device 2. In order to improve the S / N ratio, this echo is preferably the first bottom echo. However, the second bottom echo and subsequent multiple reflected echoes may be designated from the input device 2 so that the amplitude can be easily compared in the subsequent steps.

  In step S103, the phase difference sent from the initial phase difference controller 33 is set to 0. In the receiver 5, the memory 51 stores the received waveform of the first piezoelectric element 4a and the received waveform of the second piezoelectric element 4b. The synthesized amplitude is stored. In step S104, the arithmetic unit 52 weights the reception waveform of the first piezoelectric element 4a and the reception waveform of the second piezoelectric element 4b with the amplitude of the amplitude controller 3a (amplitude 3a) and the amplitude of the amplitude controller 3b (amplitude 3b), respectively. In step S105, the amplitude of the composite waveform of the echo is compared with the value stored in the memory 51 by the comparator 53. If the maximum value of the amplitude of the composite waveform of the echo is obtained, the process proceeds to step S107. If not, the process proceeds to step S106, and the second and subsequent steps are executed. In the second and subsequent steps, in step S106, the control signal generator 54 changes the ratio of the amplitude 3a and the amplitude 3b under the condition that the total amplitude is constant, and transmits it to the transmitter 3, and the same as in the first step. Then, the comparison is repeated, and the ratio of the amplitude 3a and the amplitude 3b that maximizes the amplitude of the composite waveform of the echo is calculated. That is, by changing the ratio of the amplitude 3a and the amplitude 3b, it is possible to transmit a polarized wave whose vibration direction is controlled. The polarization here can be referred to as linear polarization. Θ calculated as amplitude 3a / amplitude 3b = tan θ is an angle formed by one shear vibration direction of the polarization control probe 4 and one of the principal axis directions of the subject 7. Further, the ratio of the amplitude 3a and the amplitude 3b that minimizes the combined echo amplitude, θ calculated as amplitude 3a / amplitude 3b = tan θ is one shear vibration direction of the polarization control probe 4, the main axis of the subject 7, and 45. This is the angle between the orientation and the angle. The control signal generator 54 transmits the measurement result in the main axis direction to the display device 6, and the display device 6 displays the measurement result. Note that the subject in this example shows a case where an anisotropic material having an angle of 90 degrees is targeted.

  Here, when the amplitude of the composite waveform of the echo is the maximum value, the transmitted ultrasonic wave coincides with the principal axis direction of the material, so the ultrasonic wave becomes a single waveform. A waveform is received that is weakened by an amount that attenuates in the material. This is the largest echo received. However, when the transmission direction of the ultrasonic wave does not coincide with the main axis direction, the transmission waveform is separated into two polarized waves, and a phase difference is generated, so that a weakened composite waveform is received. By using this principle, the principal axis direction of the acoustic anisotropic material can be obtained.

Next, an initial phase difference is determined using echoes from the subject 7 used in the measurement in the principal axis direction. At this time, preferably, in step S107, the polarization control probe 4 is rotated so that the axis of the polarization control probe 4 and the main axis of the subject 7 are aligned. In step S 108, the amplitude 3 a and the amplitude 3 b are set to be equal, the phase difference (phase difference 31) input to the phase difference controller 33 is set to 0, and the combined amplitude is stored in the memory 51. In step S109, ultrasonic waves are transmitted and received, and a composite echo amplitude is calculated. In step S110, the amplitude of the composite waveform of the echo is compared with the value stored in the memory 51 by the comparator 53. If the maximum value of the amplitude of the composite waveform of the echo is obtained, the process proceeds to step S112. If not, the process proceeds to step S111 and the second and subsequent steps are executed. In step S111, the phase difference 31 is sequentially changed, and step S109 is executed again. In step S110, the phase difference 31 that maximizes the amplitude of the composite waveform of the echo is obtained. The condition that the amplitude of the composite waveform of the echo is maximum is given by the following (Equation 1) when the axis of the polarization control probe 4 and the main axis of the subject 7 coincide.
v1t−v2t = nλ + (φ / 2π) λ (Expression 1)
v1 and v2 are the sound speeds of the polarized waves in the directions of the two principal axes, and (φ / 2π) is the phase difference between the polarized waves, and is the maximum when (Equation 1) is satisfied. Replacing each value in this equation yields (Equation 2).
ΔV / V02 = (n + φ / 2π) / fz (Expression 2)
Here, V0 is the average sound speed of the polarized waves in the directions of the two principal axes, ΔV (= v1−v2) is the difference in the speed of sound of the polarized waves in the directions of the two principal axes, and f (= V0 / λ) is the ultrasonic frequency. , Z is twice the distance from the inspection surface to the reflector producing a specific echo, φ is the initial phase, and n is the interference order. Although n is 0, other integer values may be used as necessary.

  As described above, since preparations for flaw detection are completed, flaw detection is started in step S112. Here, preparations are made in advance so that the interference is maximized on the bottom surface of the subject. However, this position may be appropriately changed depending on the measurement target.

  Describe flaw detection. When the phase difference 31 is changed from the amplitude 3a, the amplitude 3b, and the phase difference 31 set in the above procedure, the waveforms interfere with each other at the position where the condition of (Equation 2) is satisfied, and the signals are strengthened. When a reflector exists at this position, a combined waveform strengthened by interference is observed. It should be noted that echoes that are ambient noise interfere and weaken each other, so that the composite waveform becomes weak, and the strengthened composite waveform is displayed with emphasis. That is, since the position of z changes in (Expression 2), the waveform interferes and strengthens at this position on z, and weakens at other positions. By reducing the phase difference, when the interference position z moves inward from the bottom surface of the subject and there is a defect or inclusion at that position, the defect or inclusion can be captured more clearly. it can. The interference waveform is sent from the calculator 52 to the display 6 and displayed.

  As described above, the flaw detection focused on the designated position is possible. Here, the focus function refers to a predetermined position to be detected by transmitting and receiving polarized waves, which are transverse wave ultrasonic waves having vibration direction components in two directions, so that the polarized waves interfere with each other at predetermined positions inside the inspection target. The control is performed so that the ultrasonic signals are strengthened and unnecessary signals at other positions are weakened.

  When the inspection object is an isotropic material, the propagation speeds of the respective transverse wave ultrasonic waves are equal to each other, so that the interference position z cannot be focused by controlling the phase difference 31.

  The polarization control probe 4 will be described with reference to FIG. The polarization control probe 4 has a structure in which a first piezoelectric element 4a and a second piezoelectric element 4b having different shear vibration directions of 90 degrees are laminated. Each piezoelectric element includes a first input / output transmission path 41a and a second input / output transmission path 41b for applying or reading a voltage waveform.

  Next, the transmitter 3 will be described with reference to FIGS. FIG. 5 is a detailed configuration diagram of the waveform generator 32. The trigger 321 is input to the delay pulse generator 322, and generates two trigger pulses having a time difference in transmission timing by a designated phase difference. The arbitrary waveform generator 323a and the arbitrary waveform generator 323b generate the same waveform based on the inputted amplitude 3a and amplitude 3b, and the voltage waveform a is synchronized with the trigger pulse sent from the delay pulse generator. And a voltage waveform b is output. As a result, a voltage waveform having an arbitrary polarization state for controlling the polarization control probe 4 can be generated. The voltage waveform a and the voltage waveform b are amplified as necessary via the amplifiers 321a and 321b, and transmitted from the first voltage waveform terminal 324a and the second voltage waveform terminal 324b, respectively.

  FIG. 6 shows the state of the polarization state generated by the polarization control probe 4. The polarization control probe 4 generates polarized waves that vibrate in two orthogonal axes, and displays the amplitude 3a, amplitude 3b, and phase difference 31 in the respective axial directions on the display 6 as polarization states. Such polarization is called elliptical polarization. This process is performed by the receiver.

  The phase difference 31 is φ where the ratio of the axial length 3c and the axial length 3d of the displayed ellipse is tan (φ / 2). An arrow 3e indicates the rotation direction of the polarization, and is counterclockwise when 0 <φ <π and clockwise when π <φ <2π.

  When the inspection object is an isotropic material, the polarization is linearly polarized.

  Next, the receiver 5 will be described with reference to FIGS. FIG. 7 shows an example of the received waveform of the designated echo. The reflected waves from the subject 7 are received by the first piezoelectric element 4a and the second piezoelectric element 4b, respectively, sent to the computing unit 52 and computed to generate a composite waveform.

  As shown in FIG. 7 (a), the received waveform 7a and the received waveform 7b of the ultrasonic wave passing through the test object having ultrasonic anisotropy change the phase difference 81, and the phase difference 81 is just an ultrasonic wave. The received waveform 7a and the combined waveform 7b of the received waveform 7b strengthen each other. On the other hand, as shown in FIG. 7B, when the phase difference 81 between the received waveform 8a and the received waveform 8b is exactly a half integer multiple, the combined waveform 8c of these received waveforms weakens. By controlling the initial phase difference, it is possible to control the ultrasonic path through which a combined waveform with constructive interference is obtained. The synthesized waveform is transmitted to the display 6 and displayed.

  FIG. 8 shows the detailed configuration of the computing unit 52. The received waveform is calculated by weighted addition 521. The composite waveform is calculated by weighting and adding the wave heights of the same reception time by the calculator 52. The weight 52a and the weight 52b can calculate the amount of change of the received polarization with respect to the transmission polarization by setting the amplitude 3a and the amplitude 3b input to the transmitter 3, respectively. By using as a weight, a projection of the received waveform in an arbitrary direction can be obtained.

  The composite waveform is transmitted and received in this way. As shown in FIG. 9, the polarization direction of the composite wave can be controlled by changing the amplitudes 3a and 3b. Here, an angle θ formed by the direction of the axis 1 and the polarization direction of the composite wave is treated as a parameter. When amplitude 3a1> amplitude 3b1 in FIG. 9A, the formed angle 3g1 is an acute angle, and when amplitude 3a2 = amplitude 3b2 in FIG. 9B, the formed angle 3g2 is 45 ° and amplitude 3a3 in FIG. 9C = When 0 and the amplitude 3b3 ≠ 0, the formed angle 3g3 is 90 °. When the angle is 0 ° to 90 °, both the amplitude 3a and the amplitude 3b are positive values, the amplitude 3a is a negative value from 90 ° to 180 °, the amplitude 3b is a positive value, and the amplitude 3a is an amplitude from 180 ° to 270 °. Both 3b can be controlled by setting the negative value from 270 ° to 360 ° by setting the amplitude 3a to a positive value and the amplitude 3b to a negative value.

  Control of the polarization direction is performed in both transmission and reception. The result of the composite waveform recorded by changing the angle formed is transmitted to the defect direction determiner 55 to determine the defect direction.

  The defect direction is determined by, for example, changing the angle formed by the polarization direction from 0 ° to 360 ° at a 1 ° pitch, and as shown in FIG. 10, the propagation time corresponding to the defect position in the received composite waveform. There is a method of comparing the amplitude value of the reflected signal appearing at the position of and determining the direction of the angle formed at the maximum value as the defect direction. By displaying the reception result and the determination result on the display 6, the inspector can evaluate the defect direction in the subject.

  According to the present embodiment, it is possible to detect the internal defect or inclusion in the subject with high accuracy and to determine the extension direction of the minute defect or inclusion.

  Next, Example 2 will be described with reference to FIG.

  FIG. 11 is a diagram schematically showing a part of the display according to the second embodiment. In this embodiment, a part of the display shown in the display 6 of FIG. 1 in the first embodiment is configured as a measurement result and a profile. In the display of FIG. 11, the description of the components having the same functions as those already described with reference to FIG. 1 is omitted.

  The profile shows the polarization dependence of the reflected signal to be inspected. The polarization dependence of the reflected signal to be inspected is recorded in the defect direction determiner 55 as a plurality of polarization dependences in a database. After the measurement data is transmitted to the defect direction determiner 55, the degree of correlation is calculated by cross-correlation processing or difference processing with each data in the database to obtain the extension direction of the inspection object. The data with the highest degree of correlation is displayed in the profile, and the degree of correlation and the extension direction of the inspection object are displayed.

  By using the determination method and the display in this embodiment, it is possible to determine the extension direction of minute defects or inclusions in a short time and with a high S / N. Furthermore, by increasing the polarization-dependent pattern recorded in the database, it is possible to determine the extension direction of minute defects or inclusions with high accuracy. However, the example shown in FIG. 11 does not limit the embodiment of the present invention.

  The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 ... Flaw detector 2 ... Input device 3 ... Transmitter 3a, 3b ... Amplitude controller 4 ... Polarization control probe 4a ... 1st piezoelectric element 4b ... 2nd piezoelectric element 5 ... Receiver 6 ... Display device 7 ... Subject 7a , 7b, 8a, 8b ... received waveforms 7c, 8c ... composite waveform 31 ... phase difference 32 ... waveform generator 33 ... phase difference controller 51 ... memory 52 ... calculator 53 ... comparator 54 ... control signal generator 55 ... defect Direction determiner 81 ... phase difference

Claims (4)

A first ultrasonic transducer having a first vibration direction;
A second ultrasonic transducer having a second vibration direction;
Controlling the phase difference and amplitude of the first transverse wave ultrasonic wave having the first vibration direction and the second transverse wave ultrasonic wave having the second vibration direction, the first ultrasonic transducer and the second ultrasonic wave conversion A transmitter for transmitting a signal to the transmitter;
A receiver that determines the direction of the reflection target by calculating the first transverse wave ultrasonic wave and the second transverse wave ultrasonic wave from the received waveforms of the first ultrasonic transducer and the second ultrasonic transducer. When,
A display for displaying the determination result obtained by the receiver;
An ultrasonic inspection apparatus characterized by comprising: The ultrasonic inspection apparatus according to claim 1,
An ultrasonic inspection apparatus comprising a polarization control probe having a structure in which the first ultrasonic transducer and the second ultrasonic transducer are stacked in a thickness direction. The ultrasonic inspection apparatus according to claim 1,
An amplitude value of a combined waveform of the first transverse wave ultrasonic wave and the second transverse wave ultrasonic wave is recorded, and a polarization direction in which the recorded amplitude becomes a maximum value is determined as an extension direction of a reflector, Ultrasonic inspection device. The ultrasonic inspection apparatus according to claim 1,
The receiver has a database of polarization dependence of reflected signals, records amplitude values of a composite waveform of the first transverse wave ultrasonic wave and the second transverse wave ultrasonic wave in a plurality of polarization directions, An ultrasonic inspection apparatus that compares the recorded data and a database of polarization dependence of the reflected signal to determine an extension direction.

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