JP2007327747A - Ultrasonic flaw inspection method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep the detection sensitivity of a flaw while displaying the accurate position of a reflecting source even in the case where a coating material and a material to be inspected change in thickness. <P>SOLUTION: A first step (steps 101-107) for measuring the thicknesses of both the coating material and the material to be inspected, a second step (step 108) for altering the delay times set to the respective vibration elements of the array probe of an ultrasonic inspection device, and a third step (step 109) for transmitting an ultrasonic wave on the basis of the delay times after alteration to inspect the flaw are executed and, even if the thicknesses of both of the coating material and the material to be inspected change, the ultrasonic waves transmitted from the respective vibration elements are converged to the position of the inspection target in the material to be inspected. Further, the thickness of the coating material is measured on the basis of the ultrasonic waves and the position of the boundary of the coating material and the material to be inspected (the surface of the material to be inspected) is specified on the basis of the measuring result while the position of the reflecting source in the material to be inspected is precisely calculated to be precisely displayed on the display device of the ultrasonic inspection device. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic flaw detection technique in a material on the deep layer side of a material to be inspected in which a plurality of materials having different propagation speeds of ultrasonic waves are laminated, and particularly has a coating material applied to the material on the deep layer side on the surface layer side. The present invention relates to an ultrasonic flaw detection method and apparatus that are effective for carrying out ultrasonic flaw detection in a deep layer material through a coating material for a material to be inspected.

  The ultrasonic flaw detection method, which is one method for nondestructive inspection of structures, etc., propagates ultrasonic waves transmitted from an ultrasonic probe into the body to be inspected, and the presence / absence, magnitude, and propagation time of reflected waves from the body under inspection. The health of the test object is evaluated by paying attention to the above. Further, in order to increase the intensity of ultrasonic waves at the examination site and improve the sensitivity of flaw detection, a technique for focusing ultrasonic waves is used. As means for focusing ultrasound, a focused ultrasound probe that focuses the ultrasound with an acoustic lens, etc., or a phased array method (also called an electronic scan method) that focuses the ultrasound by giving a delay time to multiple vibration elements Is used).

  Usually, since the coating is thinner than the thickness of the object to be inspected, the acoustic lens shape is determined and the delay time of the phased array method is set without considering the influence of the coating. Moreover, regarding the method of measuring the thickness of the steel sheet excluding the film thickness by considering the difference in sound speed between the coated film and the steel material in the coated steel material to which the coating film is applied, there is Patent Document 1, but the sensitivity of flaw detection is known. No mention is made regarding the relationship with ultrasound focusing for improving.

  In the method that uses focused ultrasonic waves for inspection, if the object to be inspected becomes thinner or the sound speed of the paint is slower than that of the object to be inspected, and the paint becomes relatively thick, the focusability of the ultrasonic wave is reduced. In some cases, the defect detection sensitivity decreases. Further, when the coating material becomes thick, the reflection source position (propagation distance from transmission of ultrasonic waves to reception) in the material to be inspected may be different from the actual position.

JP 2002-228432 A

  The problem to be solved by the present invention is that the ultrasonic wave is focused when a material to be inspected in which a plurality of materials are laminated far from the ultrasonic wave transmission source, that is, in the deep layer side, is flawlessly detected. If the material thickness on the side close to the ultrasonic transmission source, that is, the surface layer side changes, the ultrasonic focusing performance changes, and the flaw detection sensitivity at the flaw detection target position changes. It is difficult to detect the reflection source. Furthermore, when the thickness of the material on the surface layer side changes, the reflection source position (propagation time from transmission to reception of ultrasonic waves) of the flaw detection target in the inspection object differs from the actual position.

  Therefore, an object of the present invention is to improve the flaw detection performance when flaw detection is performed by ultrasonic inspection of the material farther from the ultrasonic transmission source, that is, the deep layer side of the material to be inspected in which a plurality of materials are laminated. is there.

  A basic ultrasonic flaw detection method for solving the problem is that ultrasonic waves time-controlled by a delay time are introduced into each inspection element having a coating material on the surface from each vibration element of the array probe arranged on the surface side. A first step of measuring the thickness of the coating material in the ultrasonic inspection method by the phased array method of transmitting and focusing the ultrasonic wave in the inspection material to detect flaws in the inspection material; and from the surface A second step of determining the delay time so that the ultrasonic wave is focused at a target position where the ultrasonic wave is focused in consideration of the thickness of the coating; and time-controlling the ultrasonic wave by the determined delay time. And a third step of performing the flaw detection by focusing in the material to be inspected.

  An ultrasonic flaw detection apparatus for solving the problem includes an array probe equipped with a plurality of vibration elements transmitting and receiving ultrasonic waves, and a delay time in which excitation timing of the vibration elements is set by a first delay time setting means. A pulser that vibrates the vibration element under control, a receiver that receives an electric signal from the vibration element as a reception signal, and adds the reception signal by adding time control based on the delay time to the reception signal from the receiver In a phased array type ultrasonic flaw detector comprising: an adding means for displaying; and a display means for displaying a flaw detection result based on the received signal added by the adding means. Sound velocity setting means for setting the sound velocity of the ultrasonic wave for each material, and the ultrasonic wave in the material obtained based on the received signal after the addition Calculation means for calculating the thickness of the material based on the carrying time and the set sound velocity, and changing and setting the delay time according to the thickness of the material obtained by the calculation and the focal position of the ultrasonic wave The ultrasonic flaw detection apparatus is characterized in that the excitation timing is controlled by a delay time set by the second delay time setting means during flaw detection.

  Another ultrasonic flaw detector for solving the problem includes an array probe equipped with a plurality of vibration elements transmitting and receiving ultrasonic waves, and a delay time set by a delay time setting means for the excitation timing of the vibration elements. A pulser that controls and vibrates the vibration element; a receiver that receives an electric signal from the vibration element as a reception signal; and a time control based on the delay time added to the reception signal from the receiver to add the reception signal In a phased array type ultrasonic flaw detector provided with an adding means and a display means for displaying a flaw detection result based on the received signal added by the adding means, a plurality of materials through which the ultrasonic waves pass Sound velocity setting means for setting the sound velocity of the ultrasonic wave for each material, and transmission of the ultrasonic wave in the material obtained based on the received signal after the addition. Calculating means for calculating the thickness of the material based on time and the set sound velocity; and delay time correcting means for correcting the delay time in accordance with the thickness of the material obtained by the calculation, The ultrasonic flaw detection apparatus is characterized in that the excitation timing is controlled by the delay time corrected by the delay time correction means at the time of flaw detection.

  According to the ultrasonic flaw detection method and the ultrasonic flaw detection apparatus of the present invention, even if the thickness of the surface layer material close to the ultrasonic wave transmission source changes, the ultrasonic wave is focused at a target position in the deep layer material. Therefore, it is possible to detect the reflection source at the target position without reducing the flaw detection sensitivity, and to improve the flaw detection performance.

  In an embodiment of the present invention, an ultrasonic wave is transmitted to the surface layer portion side of the surface layer portion that is the layer of the coating material and the deep layer portion that is the material to be inspected of the inspection object in which the surface of the material to be inspected is coated with the coating material. This is an example of flaw detection of the material in the deep layer with a source.

  In the first embodiment, the first step of measuring the thickness of the coating material or the coating material and the material to be inspected, and the delay set for each vibration element of the array probe based on the measured thickness values. This is implemented in a second step for changing the time and a third step for flaw detection based on the changed delay time.

  When setting the delay time in the second step, by setting the ultrasonic wave to be focused at the target position in the material to be inspected, even if the thickness of the coating material changes, the change in flaw detection sensitivity can be reduced. The reflection source can be easily detected.

  Specifically, in the ultrasonic flaw detection method based on the phased array method, the first step is performed with a delay time setting for transmitting and receiving ultrasonic waves in the vertical direction (thickness direction) in the body to be inspected, and the coating is performed based on the measurement result. The thickness of the material or coating material and the material to be inspected is measured, and the third step flaw detection is performed with a delay time set based on the thickness.

  By doing so, there is a feature that it is not necessary to prepare a plurality of array probes and the like, and can be performed by one system. In addition, by measuring the thickness of the coating material, the position of the boundary between the coating material and the material to be inspected (surface of the material to be inspected) can be specified, so that the position of the reflection source in the material to be inspected can be obtained with high accuracy. is there. Further, by setting the boundary between the coating material and the material to be inspected as the origin in the depth direction in the cross-sectional image of the phased array method, there is a feature that the monitoring location of the inspector can be set regardless of the thickness of the coating material.

  Furthermore, if a cross-sectional image is generated with the horizontal axis as the position and the vertical axis as the depth direction of the object to be inspected based on the information obtained in the above steps, the surface position of the object to be inspected is fixed on the vertical axis. Since it is possible to make the inspector's attention point constant without depending on the thickness of the coating material, there is an advantage that the inspector can evaluate quickly.

  FIG. 1 shows a measurement flow (implementation method) of the present invention. Each step from step 101 to step 107 in FIG. 1 is the first step described above, step 108 is the second step described above, and step 109 is the third step described above. 2 is an explanatory diagram of the first and second steps, and FIG. 3 is a schematic explanatory diagram of the third step.

  The flaw detection method will be described with reference to FIGS. First, the respective sound velocities necessary for measuring the thickness of the coating material 1 and the material to be inspected 2 are set in advance (step 101), and the linear scanning method is applied to the coating material 1 applied to the surface of the material to be inspected 2. The array probe 3 is installed (the probe is installed at the inspection position (step 102)).

  In this state, a delay time required for vertical flaw detection is set (step 103), and the first measurement is performed by transmitting and receiving ultrasonic waves (step 104). A plurality of strip-shaped micro vibrators constituting the array probe are set as one block, a delay time is set, and a drive region of the vibrator is sequentially switched to inspect a certain region (scanning in FIG. 2). .

  An example of a received waveform of an ultrasonic wave at an arbitrary position is shown in the middle part of FIG. When ultrasonic waves are incident on the inspection material 2 vertically, the surface of the inspection material 2, that is, the reflected wave (reflection wave A) from the boundary surface between the coating material 1 and the inspection material 2, and the inspection material 2 A reflected wave (reflected wave B) from the bottom surface is obtained. In addition, a cross-sectional image in the lower part of FIG. 2 is an image obtained by arranging the received waveforms at each position.

  In this way, the measurement data is displayed in the form of a received waveform or a cross-sectional image (step 105). Using the received waveform and two cursors (cursor A, cursor B) on the cross-sectional image, the cursor A is set to the reflected wave (reflected wave A) from the surface of the inspection object 2 and the cursor B is set to the bottom surface of the inspection object 2 Is set to the reflected wave (reflected wave B) from (step 106). The time from the preset position of the coating material 1 to the cursor A (time to the reflected wave A) and the time difference between the cursor A and the cursor B (time difference between the reflected wave B and the reflected wave A) are measured.

  By multiplying the two times (time difference) by the speed of sound set in step 101, the thicknesses of the coating material 1 and the material to be inspected 2 can be obtained (step 107). In consideration of the measured thickness of the coating material 1, a delay time is determined so that the ultrasonic wave can be focused on the point to be focused in the material to be inspected 2, and the time is set (step 108: second step).

  FIG. 3 shows an example in which flaw detection is performed with the ultrasonic beam directed in an oblique direction, assuming that there is a defect 4 on the back surface of the material 2 to be inspected. As an example when the thickness of the coating material 1 is not taken into account, an ultrasonic beam A in FIG. 3 is shown. Here, the coating material 1 is thick and the ultrasonic beam is focused near the center of the material 2 to be inspected. Therefore, the reflected wave from the defect 4 on the bottom surface of the inspection object 2 is small and may not be detected (in the case of the ultrasonic beam A in FIG. 3).

  On the other hand, the ultrasonic beam B in which the delay time is set in consideration of the thickness of the coating material 1 is focused on the bottom surface of the material to be inspected 2, and the reflected wave from the defect 4 on the bottom surface becomes large. Detection is possible (in the case of the ultrasonic beam B in FIG. 3) (steps 109 and 110).

  It is determined whether or not the inspection has been completed at the flaw detection position (step 111). If inspection is required at the next position, the probe is moved to that position (step 112), and the delay time setting for vertical flaw detection is set (step 103). Repeat from step).

  By performing the above flaw detection method, it is possible to detect a defect near the bottom surface of the inspection object 2 with high sensitivity as shown in FIG. In FIG. 3, the focus position of the ultrasonic beam is the bottom surface of the material to be inspected 2, but it is also possible to focus on an arbitrary position of the material to be inspected 2. Furthermore, even when the coating material 1 is thick and the sound speed is different from the sound speed of the material 2 to be inspected, the position of the reflection source (defect 4) can be evaluated and displayed with high accuracy.

  An apparatus configuration for realizing the ultrasonic flaw detection method described above is shown in FIG. In the sound speed setting means 20, the sound speeds of the coating material 1 and the material to be inspected 2 are input with a keyboard or the like and stored in a memory. Based on a command from the control means 10 such as a personal computer, the thickness measurement delay time setting means 11 sets the thickness measurement delay time (delay previously stored in the control means) of the drive element group (1 block). .

  The thickness measuring delay time setting means 11 and the pulser 13 to be driven are connected via a transmission switch 12, and ultrasonic waves are transmitted from the elements in the array probe 3 connected to the pulser 13. The reflected wave from the inspection object 2 is received by the elements in the array probe 3 and sent to the AD converter 16 via the receiver 14 and the receiving switch 15.

The AD converter 16 converts an analog signal from each element into a digital signal, and sends the digital signal to the adding means 17. The adding unit 17 delays the signal based on the time set in the thickness measurement delay time setting unit 11 with respect to the plurality of digital signals, and adds all signals after the delay by the adding circuit. One received signal obtained by this addition is
It is sent to the display means 18 such as a CRT and displayed in correspondence with the drive element position in the array probe 3.

  Next, a cross-sectional image is displayed on the display unit 18 by sequentially switching and scanning the driving elements, or by scanning (moving) the array probe 3. The cursors A and B are moved / displayed to a position to be set by the cursor setting means 19 such as a mouse or a keyboard, and the propagation time (and propagation time difference) is measured.

  In the received waveform and cross-sectional image of FIG. 2, the measured value of the propagation time from the time corresponding to the preset coating material surface to the cursor A or the cursor B is sent to the thickness calculating means 21 such as a multiplier, The thickness calculation means 21 calculates the thickness by the product of the propagation time and the sound speed set in the sound speed setting means 20, and stores it in the memory. In response to a command from the control means 10, the thickness measurement value is transmitted and displayed on the display means 18 such as a CRT and transmitted to the flaw detection delay time setting means 22.

The flaw detection delay time setting means 22 sets a delay time that can be focused at a target position of the material to be inspected 2 in consideration of the thickness of the coating material 1. Based on this delay time, the pulser 13 is driven, ultrasonic waves are transmitted from the array probe, and flaw detection is started. The reflected wave from the material to be inspected 2 is received by the array probe, and a plurality of digitized reception signals are added by the adding means 17 via the receiver 14, the receiving switch 15, and the AD converter 16. The signal after the addition is sent to the display means 18 and displayed in correspondence with the drive element position in the array probe 3.

  2 and 3, the bottom surface reflected wave (reflected wave B) of the material to be inspected 2 is obtained, but the reflected wave from the surface of the material to be inspected 2 (reflected wave A: the coating material 1 and Since the coating material 1 on the surface of the material to be inspected 2 can be taken into account and the bottom surface reflected wave (reflected wave B) cannot be obtained, the inside of the material to be inspected 2 can be obtained. There is no problem with the inspection.

  FIG. 5 shows the flaw detection method at this time. The difference from the flaw detection method of FIG. 1 is that only the cursor for setting the surface of the inspection object 2 is set (step 120) and only the thickness of the coating material is measured (step 121). Therefore, the cursor for the received waveform and the cross-sectional image in this case is also only the cursor A.

  FIG. 6 shows an example in which a cursor C is provided by increasing one cursor. The cursor C is for setting the surface of the coating material 1 (the surface of the array probe 3). Thereby, the thickness of the coating material 1 can be measured more accurately. Of course, a method of setting two cursors, cursor A and cursor C, in combination with the case of one cursor in FIG.

  In the first embodiment, the linear scan method is used in the phased array method. FIG. 7 shows an example of the sector scan method. In FIG. 7, the sector scan range (angle) is set in a range including the vertical flaw detection area. As a result, as shown in the lower part of FIG. 7, the surface of the material to be inspected 2 (the boundary between the coating material 1 and the material to be inspected 2), the bottom surface, and the reflected waves from the defects (reflected waves A, B, C) are simultaneously generated. Obtainable.

  The reception waveform of line A corresponding to the vertical flaw detection is shown in the upper stage, and the reception waveform of line B corresponding to the oblique flaw detection is shown in the middle stage. The method for measuring the thickness of the coating material 1 and the material to be inspected 2 in the received waveform on the line A is the same as in the case of FIG. In the case of the sector scan method, the results from the thickness measurement to the flaw detection (vertical or oblique angle) can be obtained with a single measurement. Therefore, in the first step flaw detection, the delay time due to the thickness of the coating material 1 is reduced. When the change is not necessary, there is an advantage that the second step and the third step can be omitted.

  That is, from another viewpoint, there is an advantage that the thickness of the coating material 1 and the material to be inspected 2 can be measured at the same time as the defect detection by one flaw detection.

  As a display example of the sector scan method, FIG. 8 shows a result of detecting up to a defect (slit) on the bottom surface of the inspection object 2 by a single flaw detection. FIG. 9 shows the flaw detection method by the sector scan method, and FIG. 10 shows the apparatus configuration. 9 differs from the flaw detection method of FIG. 1 in the delay time setting portion (step 130 and step 132) for setting the delay time over a certain angle range, and determines whether or not the delay time is changed (step 131). Has been added.

  In the case of the sector scan method shown in FIG. 10, switching of the drive elements in units of blocks as shown in FIG. 2 is not required, so that the transmission switch 12 and the reception switch 15 are not required. Furthermore, since it is necessary to set the delay time over a certain angle range, the point that the delay time setting means 22 is the correction means 23 is different from FIG.

  The above description does not consider the cross-section display method, and the vertical axis (time: time: when the thickness of the coating material 1 changes even when the thickness of the material to be inspected 2 is constant or the depth range to be inspected is constant. The monitoring position (the position of the reflection source such as a defect) changes on the distance in the Z direction).

  Therefore, as shown in FIG. 11, the origin of the vertical axis of the cross-sectional image is always the surface of the material to be inspected 2 (boundary between the material to be inspected 1 and the material to be inspected 2). Since the monitoring position (the position of the reflection source such as a defect) is constant, there is an advantage that the inspector can quickly evaluate. FIG. 11 is an explanatory diagram of the sector scan method, but the same applies to the linear scan method.

  In the embodiment of the present invention, it is possible to inspect the inside of a material to be inspected with high sensitivity by focusing the inside of the material to be inspected according to the thickness of the material to be coated. The reliability of the inspection material is improved. As a result, it is possible to improve the operating rate of the equipment by preventing malfunctions. In addition, by considering the cross-sectional display method, the monitoring range can be made constant regardless of the thickness of the coating material, which may lead to a reduction in inspection and evaluation time. In this way, although there is no coating material layer, the ultrasonic wave can be accurately acted on during inspection, so that the flaw detection performance of the coated inspection material can be improved.

  The present invention can be used for a nondestructive inspection technique using ultrasonic waves called ultrasonic inspection or ultrasonic flaw detection.

It is explanatory drawing which showed the implementation method of ultrasonic flaw detection. It is explanatory drawing which showed typically the 1st step in FIG. It is explanatory drawing which showed typically the 2nd and 3rd step in FIG. It is explanatory drawing which showed the structure of the ultrasonic flaw detector. It is explanatory drawing which showed the other implementation method of ultrasonic flaw detection. It is explanatory drawing which showed typically the 1st step of the other Example. It is explanatory drawing which showed typically the implementation method of the sector scan method. It is explanatory drawing which showed the example of a display of the sector scan method. It is explanatory drawing which showed the implementation method of the sector scan method. It is explanatory drawing which showed the apparatus structure of the sector scan method. It is explanatory drawing which showed the example of a display of the other Example typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Paint material, 2 ... Test material, 3 ... Array probe, 4 ... Defect, 10 ... Control means, 11 ... Thickness measurement delay time setting means, 12 ... Transmission switch, 13 ... Pulser, 14 ... Receiver,
DESCRIPTION OF SYMBOLS 15 ... Reception switching device, 16 ... AD converter, 17 ... Addition means, 18 ... Display means, 19 ... Cursor setting means, 20 ... Sound speed setting means, 21 ... Thickness calculation means, 22 ... Flaw detection delay time setting means, 23: Delay time correction means.

Claims (8)

Ultrasonic waves that are time-controlled with a delay time are transmitted from each vibration element of the array probe arranged on the surface side into the inspection material having a coating material on the surface, and the ultrasonic waves are focused in the inspection material. In the ultrasonic inspection method by the phased array method for flaw detection in the inspection object,
A first step of measuring the thickness of the coating material;
A second step of determining the delay time so that the ultrasonic wave is focused on a target position for focusing the ultrasonic wave in consideration of the thickness of the coating from the surface;
An ultrasonic flaw detection method comprising: a third step of performing the flaw detection by focusing the ultrasonic wave in the inspection object by controlling the time with the predetermined delay time.   2. The ultrasonic flaw detection method according to claim 1, wherein the thickness of the coating material and the material to be inspected is measured in the first step.   3. The first step according to claim 1, wherein a sector scan of the ultrasonic wave is performed, and a flaw detection result obtained by performing the sector scan performs the first step from a flaw detection component in the thickness direction of the inspection object. Ultrasonic flaw detection method characterized by.   4. The coating material according to claim 1, wherein a cursor for setting a boundary between the coating material and the material to be inspected is displayed on a display device for displaying the flaw detection result. Sonic flaw detection method.   5. The ultrasonic flaw detection method according to claim 4, wherein a cursor for setting the surface of the coating material is displayed on the display device.   6. The ultrasonic flaw detection method according to claim 4, wherein a cursor for setting a bottom surface of the inspection object is displayed on a display device that displays the flaw detection result. An array probe equipped with a plurality of vibration elements for transmitting and receiving ultrasonic waves;
A pulser that vibrates the vibration element by controlling the excitation timing of the vibration element with the delay time set by the first delay time setting means;
A receiver for receiving an electrical signal from the vibration element as a reception signal;
Adding means for adding the received signal by adding time control based on the delay time to the received signal from the receiver;
Display means for displaying a flaw detection result based on the received signal added by the adding means;
In a phased array type ultrasonic flaw detector equipped with
A sound speed setting means for setting, for each material, the sound speed of the ultrasonic wave in a plurality of materials through which the ultrasonic wave passes;
Calculation means for calculating the thickness of the material based on the propagation time of the ultrasonic wave in the material obtained based on the received signal after the addition and the set sound velocity;
Second delay time setting means for changing and setting the delay time according to the thickness of the material obtained by the calculation and the focus position of the ultrasonic wave,
The ultrasonic flaw detection apparatus is characterized by controlling the excitation timing with a delay time set by the second delay time setting means during flaw detection. An array probe equipped with a plurality of vibration elements for transmitting and receiving ultrasonic waves;
A pulser that vibrates the vibration element by controlling the excitation timing of the vibration element with a delay time set by a delay time setting means;
A receiver for receiving an electrical signal from the vibration element as a reception signal;
Adding means for adding the received signal by adding time control based on the delay time to the received signal from the receiver;
Display means for displaying a flaw detection result based on the received signal added by the adding means;
In a phased array type ultrasonic flaw detector equipped with
A sound speed setting means for setting, for each material, the sound speed of the ultrasonic wave in a plurality of materials through which the ultrasonic wave passes;
Calculation means for calculating the thickness of the material based on the propagation time of the ultrasonic wave in the material obtained based on the received signal after the addition and the set sound velocity;
A delay time correcting means for increasing or decreasing the delay time according to the thickness of the material obtained by the calculation;
The ultrasonic flaw detection apparatus is characterized in that the excitation timing is controlled by the delay time corrected by the delay time correction means at the time of flaw detection.

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