JP2018054354A - Ultrasonic flaw detector, data processing device and ultrasonic flaw detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively discriminate between a defect echo and noise even for an object whose noise in ultrasonic flaw detection is large.SOLUTION: An ultrasonic flaw detector 100 according to an embodiment comprises: an ultrasonic array probe 10 having a plurality of ultrasonic elements 11; a potential difference application unit 21 capable of applying a potential difference that can cause vibration to occur in the ultrasonic element 11; a delay time computation unit 31 for calculating a delay time for delaying the timing with which the ultrasonic element 11 transmits/receives an ultrasonic wave; a switching unit 22 for switching between a state in which the potential difference application unit 21 applies and a state in which the potential difference application unit 21 does not apply a potential difference to the ultrasonic element 11; a feature value calculation unit 35 for calculating a feature value relating to a composite echo synthesized in accordance with the delay time; a feature value change calculation unit 36 for calculating a change of feature value relative to a change of flaw detection condition of ultrasonic wave to an inspection object 1; and a display unit 60 for displaying the calculated change of a feature value.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an ultrasonic flaw detection apparatus, a data processing apparatus, and an ultrasonic flaw detection method.

  Ultrasonic testing (UT) is a technique that enables non-destructive confirmation of the surface and internal soundness of a structural material, and is an indispensable inspection technique in various fields. Phased array ultrasonic flaw test (PAUT: Phased Array UT) that can form arbitrary waveforms by arranging small piezoelectric elements for ultrasonic transmission / reception and transmitting ultrasonic waves by shifting the timing (delay time) for each piezoelectric element is It is also widely used in industrial applications.

  Phased array ultrasonic flaw detection technology can detect a wide area with a single flaw detection, flaw detection at multiple angles, or support complex shapes compared to a monocular probe that can emit ultrasonic waves only at a predetermined angle. There is a great attraction that the work man-hours can be reduced. In the phased array ultrasonic flaw detection technology, various efforts have been made to further speed up the inspection. Originally, in a phased array ultrasonic flaw detection test, a plurality of element groups are excited with a time delay, thereby freely controlling the flaw detection refraction angle and the focal depth.

  In this case, one set of delay time is given to one element group to obtain a flaw detection result of one waveform (hereinafter referred to as one sequence). When the number of sequences exceeds, for example, 1000, Measurement time becomes longer. Thus, attempts have been made to reduce the measurement time by reducing the number of times of transmitting and receiving ultrasonic waves as much as possible.

  In the first place, in the above-described phased array ultrasonic testing, when there are n transmission / reception elements, if there are n reception waveforms for each transmission element, that is, n × n raw waveforms can be recorded, the waveform follows the delay time. All conditions can be reconfigured offline by shifting and adding the time axes. Several attempts have been made to speed up the phased array ultrasonic testing using this concept.

  For example, a technique for performing ultrasonic transmission / reception only once and synthesizing received signals obtained there under an arbitrary flaw detection condition, or a sequence for transmitting ultrasonic waves with one element and receiving ultrasonic waves with multiple elements, A technique is known in which a pseudo transmission / reception focus is made possible by changing the element for transmitting the signal repeatedly and synthesizing the obtained waveforms.

  Further, in order to prevent erroneous recognition of noise as a defect in an inspection object such as a welded portion where there is anisotropy or crystal grains are coarsened, improvement of the signal-to-noise ratio (SN ratio) is a problem. . For example, in a welded part inspection, a technique for designing a dedicated probe is known in addition to a technique using a database or a simulation. Recently, a flaw detection method in which the size of the array element is changed is also known.

Japanese Patent No. 3770465 JP 2009-281805 A Japanese Patent No. 5588918 JP 2001-343370 A

  However, the above-mentioned various measures for preventing erroneous recognition of noise as a defect are aimed only at improving the fundamental signal-to-noise ratio (S / N ratio), and the defect echo (the reflected wave of the ultrasonic wave reflected by the defect). ) And noise are still difficult to distinguish effectively.

  Based on the above, the embodiment of the present invention is based on the fact that the behavior of the noise signal strength change and the defect echo signal strength change when the flaw detection conditions are changed is different from that on ultrasonic flaw detection such as a welded portion. An object of the present invention is to enable effective discrimination of a defect echo and noise even in a noisy object without prior investigation or comparison with a database.

  In order to achieve the above-described object, the ultrasonic flaw detection apparatus according to the present embodiment includes a plurality of ultrasonic elements arranged in parallel to transmit ultrasonic waves to an inspection target and receive ultrasonic waves reflected by the inspection target. An ultrasonic array probe, a potential difference applying unit capable of applying a potential difference causing vibration to the ultrasonic element, and a delay time calculating unit for calculating a delay time for shifting the timing at which the ultrasonic element transmits and receives the ultrasonic wave A switching unit that switches between a state in which the potential difference applying unit applies a potential difference to the ultrasonic element and a state in which the potential difference applying unit does not apply a potential difference to the ultrasonic element, and a received wave received by the ultrasonic element A feature amount calculation unit that calculates a feature amount related to a synthesized echo that is synthesized according to the delay time; and A feature quantity variation calculating unit for calculating a change, a display unit for displaying the calculated feature quantity variation, characterized in that it comprises a.

  Further, according to the present embodiment, in a data processing apparatus that processes signal data transmitted to and received by an ultrasonic array probe having a plurality of ultrasonic elements, the timing at which the ultrasonic elements transmit and receive ultrasonic waves is shifted. A delay time calculating unit that calculates a delay time for the switching, a switching unit that switches between a state in which the potential difference applying unit applies a potential difference to the ultrasonic element and a state in which the potential difference applying unit does not apply a potential difference to the ultrasonic element. A feature amount calculation unit that calculates a feature amount related to a synthesized echo obtained by synthesizing the received wave received by the ultrasonic element according to the delay time; and a feature amount of the feature amount with respect to a change in a flaw detection condition of the ultrasonic wave to the inspection target A feature amount change calculation unit that calculates a change and a display unit that displays the calculated feature amount change are provided.

  Further, in the ultrasonic flaw detection method according to the present embodiment, an image inside the inspection object is based on a composite waveform of an ultrasonic wave received from the ultrasonic element of the ultrasonic array probe to the inspection object by the imaging unit. A video creation step for creating a feature quantity, a feature quantity calculation section for calculating a feature quantity based on the video, and a feature quantity change calculation section for changing the feature quantity in response to a change in flaw detection conditions. A feature amount change calculating step for calculating the feature amount, and a display unit displaying the change in the feature amount.

  According to the embodiment of the present invention, it is possible to effectively determine a defect echo and noise.

It is a block diagram which shows the structure of the ultrasonic flaw detector which concerns on 1st Embodiment. It is a notional longitudinal cross-sectional view which shows transmission of the ultrasonic wave of the ultrasonic flaw detector which concerns on 1st Embodiment. It is a conceptual diagram which shows the advancing state of the ultrasonic wave of the ultrasonic flaw detector which concerns on 1st Embodiment. It is a conceptual diagram for demonstrating the advancing direction of the ultrasonic wave of the ultrasonic flaw detector which concerns on 1st Embodiment. It is a graph which shows the time change of the synthetic | combination signal of the echo signal by the ultrasonic flaw detector which concerns on 1st Embodiment. It is a conceptual diagram which shows the case where there exists a defect in a flaw detection space area | region. It is the imaging result of a flaw detection space area | region when a defect exists in a flaw detection space area | region. It is a conceptual diagram which shows the case where there exists a welding part other than a defect in a flaw detection space area | region. It is an image obtained as a result of imaging of a flaw detection space area when there is a weld in addition to a defect in the flaw detection space area. It is a 1st image explaining extraction of the significant echo area | region from the imaging result of the flaw detection space area | region in the ultrasonic flaw detection method which concerns on 1st Embodiment, (a) is before extraction of a significant echo area | region, (b) Indicates after extraction of a significant echo area. It is a 2nd image explaining extraction of the significant echo area | region from the imaging result of the flaw detection space area | region in the ultrasonic flaw detection method which concerns on 1st Embodiment, (a) is before extraction of a significant echo area | region, (b). Indicates after extraction of a significant echo area. It is an image of the echo intensity distribution by imaging of a flaw detection space region when the flaw detection refraction angle β is changed in the ultrasonic flaw detection method according to the first embodiment, (a) is β is 20 °, (b) Is the case where β is 30 ° and (c) is the case where β is 40 °. It is a graph which shows the example of the change of echo intensity at the time of changing the flaw detection refraction angle (beta) in the ultrasonic flaw detection method which concerns on 1st Embodiment. It is a flowchart which shows the procedure in the ultrasonic flaw detection method which concerns on 1st Embodiment. It is a graph explaining the example of the determination content of the presence or absence of the defect in the defect determination part in the ultrasonic flaw detection method which concerns on 1st Embodiment. It is a flowchart which shows the procedure of the determination in the ultrasonic flaw detection method which concerns on 1st Embodiment. It is a graph which shows the example of the change of echo intensity at the time of changing the focal depth F in the modification of the ultrasonic flaw detection method which concerns on 1st Embodiment. It is a block diagram which shows the structure of the ultrasonic flaw detector based on 2nd Embodiment. It is an image which shows the example of the change of the center position of the echo area | region of a flaw detection space area | region at the time of changing the flaw detection refraction angle (beta) in the ultrasonic flaw detection method which concerns on 2nd Embodiment, (a) is (beta) 20 degrees. (B) shows the case where β is 30 °, and (c) shows the case where β is 40 °. It is a graph which shows the example of the change of the center position of the echo area | region of a flaw detection space area | region at the time of changing flaw detection refraction angle (beta) in the ultrasonic flaw detection method which concerns on 2nd Embodiment. It is a block diagram which shows the structure of the ultrasonic flaw detector which concerns on 3rd Embodiment. The graph which shows the example of the change of the frequency distribution of the luminance value in each pixel in a flaw detection space area | region at the time of changing flaw detection refraction angle (beta) in the ultrasonic flaw detection method which concerns on 3rd Embodiment, and shows the case of noise It is. The graph which shows the example of the change of the frequency distribution of the luminance value in each pixel in a flaw detection space area | region at the time of changing the flaw detection refraction angle (beta) in the ultrasonic flaw detection method which concerns on 3rd Embodiment, and shows the case of a defect It is. It is a block diagram which shows the structure of the ultrasonic flaw detector which concerns on 4th Embodiment. It is a graph which shows the example of the change of echo intensity at the time of changing flaw detection refraction angle (beta) in the ultrasonic flaw detection method which concerns on 4th Embodiment. FIG. 10 is a conceptual explanatory diagram for explaining integration in an ultrasonic flaw detection method according to a fourth embodiment, and when a flaw detection refraction angle as a flaw detection condition is in a range from βs to βe, (a) is a flaw detection refraction angle. (B) shows the integrated result, and (c) shows the integrated result. It is a figure for the comparison explaining the effect of the integration in the ultrasonic flaw detection method concerning a 4th embodiment, and (a) shows the case where it unifies, and (b) shows the case where it unifies. It is a block diagram which shows the structure of the ultrasonic flaw detector which concerns on 5th Embodiment. It is a flowchart which shows the procedure in the ultrasonic flaw detection method which concerns on 5th Embodiment. It is a block diagram which shows the state of each transmission of the ultrasonic wave in the ultrasonic flaw detection method which concerns on 5th Embodiment. It is a wave form diagram which shows a part of echo waveform by transmission of the ultrasonic wave in the ultrasonic flaw detection method which concerns on 5th Embodiment. It is a wave form diagram explaining the delay time at the time of the transmission of the ultrasonic wave in the ultrasonic flaw detection method which concerns on 5th Embodiment, and reception. It is a wave form diagram which shows the synthetic | combination waveform of the echo by the ultrasonic flaw detection method which concerns on 5th Embodiment. It is a block diagram which shows the structure of the ultrasonic flaw detector which concerns on 6th Embodiment.

  Hereinafter, an ultrasonic flaw detection apparatus, a data processing apparatus, and an ultrasonic flaw detection method according to embodiments of the present invention will be described with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted.

[First Embodiment]
FIG. 1 is a block diagram showing the configuration of the ultrasonic flaw detector according to the first embodiment. The ultrasonic flaw detector 100 includes an ultrasonic array probe 10, a transmission / reception unit 20, a calculation unit 30, a storage unit 40, a control calculation unit 50, a display unit 60, and an input unit 70. The ultrasonic flaw detector 100 is intended to detect a defect 2 inherent in the inspection object 1.

  The ultrasonic array probe 10 has a plurality of ultrasonic elements 11. The ultrasonic elements 11 are arranged in a one-dimensional manner (one direction) at a constant interval. The ultrasonic element 11 is a ceramic or composite material, or a piezoelectric element that can generate ultrasonic waves by other piezoelectric effects, a piezoelectric element made of a polymer film or other mechanism that can generate ultrasonic waves, and a damping of ultrasonic waves. It is assumed that the damping material, the front plate attached to the ultrasonic oscillation surface, or a combination thereof, is generally referred to as an ultrasonic probe.

  In addition, although the example which has the ultrasonic element 11 in which the ultrasonic array probe 10 was arranged in one dimension was demonstrated, it is not limited to this. For example, a 1.5-dimensional array probe in which piezoelectric elements are divided in a non-uniform size in the depth direction of a linear array probe, a matrix array probe in which piezoelectric elements are two-dimensionally arranged, and ring-shaped piezoelectric elements are concentric. Arranged ring array probe, split ring array probe in which the piezoelectric elements of the ring array probe are divided in the circumferential direction, non-uniform array probe in which the piezoelectric elements are non-uniformly arranged, circle in which the elements are arranged in the circumferential direction of the arc An arc-shaped array probe, a spherical array probe in which elements are arranged on a spherical surface, or the like may be used.

  Also, so-called tandem flaw detection using a combination of a plurality of these array probes regardless of the type may be used. The above array probes include those that can be used regardless of whether in the air or underwater by caulking or packing.

  When the inspection object 1 is inspected, an acoustic propagation medium 5 called a wedge is provided between the ultrasonic array probe 10 and the inspection object 1. The acoustic propagation medium 5 is for making an ultrasonic wave incident on the inspection object 1 at an angle with high directivity. As the acoustic propagation medium 5, an isotropic material capable of propagating ultrasonic waves and grasping acoustic impedance is used. Note that the acoustic propagation medium 5 does not have to be used when the surface of the inspection object 1 is flat.

  Examples of the isotropic material used as the acoustic propagation medium 5 include acrylic, polyimide, gel, and other polymers. The front panel (not shown) of the ultrasonic element 11 has an acoustic impedance close to or the same material, and the inspection object 1 has an acoustic impedance close to or the same material. Alternatively, a composite material that changes acoustic impedance stepwise or gradually may be used.

  Further, in order to prevent the multiple reflected waves in the acoustic propagation medium 5 from affecting the flaw detection results, a damping material is disposed inside and outside the acoustic propagation medium 5, a mountain-shaped wave-eliminating shape is provided, and a multiple reflection reduction mechanism is provided. May have. In the following description, the display of the acoustic propagation medium 5 may be omitted in an explanatory diagram when an ultrasonic wave is incident on the inspection object 1 from the ultrasonic array probe 10.

  The contact part of the path from the ultrasonic array probe 10 to the inspection object 1, that is, the contact part between the ultrasonic array probe 10 and the acoustic propagation medium 5, and the contact part between the acoustic propagation medium 5 and the inspection object 1, or acoustic An acoustic contact medium (not shown) is used at the contact portion between the ultrasonic array probe 10 and the inspection object 1 when the propagation medium 5 is not used in order to propagate ultrasonic waves. The acoustic contact medium is a medium capable of propagating ultrasonic waves, such as water, glycerin, machine oil, castor oil, acrylic, polystyrene, and gel.

  The transmission / reception unit 20 includes a potential difference application unit 21, a switching unit 22, and an AD conversion unit 23. The potential difference applying unit 21 applies a potential difference that causes vibration to the ultrasonic element 11 to the ultrasonic elements 11 that are connected so as to be applied. The switching unit 22 switches between each of the ultrasonic elements 11 between a state connected to the potential difference applying unit 21 and a state not connected to the potential difference applying unit 21 based on a command from the control calculation unit 50. Do. The AD conversion unit 23 digitizes a signal (echo signal) received by each of the ultrasonic elements 11 and outputs the digitized waveform to the storage unit 40 as a digital ultrasonic waveform.

  The storage unit 40 includes a signal processing information storage unit 41 and a parameter storage unit 42. The signal processing information storage unit 41 stores ultrasonic echo signals (digital ultrasonic waveform data) received by the transmission / reception unit 20. The calculation processing result in the calculation unit 30 is stored as processing information. The parameter storage unit 42 stores determination parameters used for determination by the defect determination unit 37 of the calculation unit 30 described later. The determination parameter is input from the input unit 70.

  FIG. 2 is a conceptual longitudinal sectional view showing transmission of ultrasonic waves. This shows flaw detection using a general phased array. In order to make an ultrasonic wave enter the inspection object 1 at an arbitrary flaw detection refraction angle β and a focal position, an appropriate time delay is applied to each ultrasonic element 11 constituting the drive element group defined in the ultrasonic array probe 10. To oscillate. This makes it possible to control the incident angle α of the ultrasonic wave on the inspection object 1 and the focal position (not shown or described).

  The scanning element group in the ultrasonic array probe 10 is scanned to obtain a cross-sectional view in the direction in which the ultrasonic elements 11 are arranged, and the position of the driving element group is fixed and only the flaw detection refraction angle β is obtained. Sector scanning method for obtaining a fan-like cross-sectional view by scanning In this embodiment, the linear scan method is typically described as an example, but in addition to the sector scan method, a plurality of ultrasonic waves such as Dynamic Depth Focusing (DDF) that changes the focal depth according to the region to be measured. Other flaw detection methods implemented by controlling the delay time of the element 11 may be used.

  The calculation unit 30 includes a delay time calculation unit 31, a signal synthesis unit 32, an imaging unit 33, an extraction unit 34, an intensity distribution calculation unit 35a as a feature amount calculation unit 35, and an intensity distribution change calculation as a feature amount change calculation unit 36. A unit 36a and a defect determination unit 37;

  The delay time calculation unit 31 applies a voltage from the potential difference application unit 21 to the plurality of ultrasonic elements 11 as the drive element group in order to focus the ultrasonic waves to a predetermined flaw detection refraction angle β and a focal depth. The delay time for shifting the timing of switching to, that is, the timing of transmitting ultrasonic waves is calculated. Based on this delay time, the switching unit 22 performs switching and puts each ultrasonic element 11 into a voltage application state. In other words, by driving each ultrasonic element 11 based on the delay time calculated from the desired flaw detection condition in the delay time calculation unit 31, flaw detection under the desired flaw detection condition can be performed by the ultrasonic array probe 10. . The flaw detection conditions are flaw detection parameters when performing ultrasonic flaw detection. In this embodiment, the flaw detection conditions include at least one of the flaw detection refraction angle β and the focal depth, but other necessary conditions for flaw detection are also included. It may be a flaw detection parameter.

  The delay time is calculated from the relative positional relationship between the ultrasonic array probe 10 and the inspection object 1, the flaw detection refraction angle β, the focus depth, the surface shape of the inspection object 1, the acoustic propagation medium 5 and the sound velocity in the inspection object 1. .

  At this time, even if the surface shape of the inspection object 1 is not a general flat surface or an inclined flat surface but has a curvature or a concavo-convex portion, geometric calculation can be performed in consideration thereof. The surface shape of the inspection object 1 may be calculated using the time of flight of the ultrasonic wave emitted from the ultrasonic element 11 or may be read from shape data such as an existing drawing. Further, the inspection target surface shape measuring means such as a camera or a laser distance meter may be attached to the ultrasonic array probe 10 or separately provided in the vicinity thereof. Also, the delay time itself can be read and used in advance.

In inspecting the inspection object 1, for example, there may be an inspection for each region of the inspection object 1. Instead of using all the ultrasonic elements 11 included in the ultrasonic array probe 10,
Some of the ultrasonic elements 11 may be used simultaneously as the same group, and the groups may be moved sequentially. As described above, the ultrasonic elements 11 used in the same group will be referred to as a drive element group as described above. Note that the drive element group may be all the ultrasonic elements 11 in the ultrasonic array probe 10.

  In addition, the delay time calculation unit 31 similarly calculates a delay time for shifting the timing on the receiving side.

  The signal synthesizer 32 uses the data of each digital ultrasonic waveform (echo waveform) received by the ultrasonic element 11 of the drive element group, and receives each according to the delay time on the receiving side of each ultrasonic element 11. The digital ultrasonic waveform data (echo waveform signal) is moved in time axis and added or averaged to obtain a synthesized signal (synthesized echo signal). Note that the synthesis may be a method other than addition or averaging. The synthesis result in the signal synthesis unit 32 is stored in the signal processing information storage unit 41.

  FIG. 3 is a conceptual diagram showing the progress of ultrasonic waves of the ultrasonic flaw detector according to the first embodiment. Each line indicating the path of the ultrasonic wave is transmitted to each of the plurality of ultrasonic elements 11 belonging to the respective drive element group while delaying the delay time calculated by the delay time calculation unit 31.

  FIG. 4 is a conceptual diagram for explaining the traveling direction of ultrasonic waves. Now, a case where there are four ultrasonic elements 11 belonging to the drive element group will be described as an example. The transmission positions where ultrasonic waves are emitted from each of the ultrasonic elements 11 are P1, P2, P3 and P4, and the ultrasonic waves emitted from these transmission positions are C1, C2, C3 and C4.

  If no delay time is provided, the ultrasonic wave propagates while traveling parallel to the front surface of the ultrasonic array probe 10, that is, the straight line L 0 of the array of ultrasonic elements 11.

  On the other hand, if the transmission time from each transmission position is shifted by Δt, the distance traveled by each ultrasonic wave is gradually delayed. That is, the ultrasonic wave emitted from P1 proceeds to C1, but the latest ultrasonic wave emitted from P4 proceeds only to C4. As a result, the envelope LC is inclined from the straight line L0 in which the ultrasonic elements 11 are arranged. If a vector extending in the direction perpendicular to the envelope LC from the center of the ultrasonic element 11 belonging to the drive element group is a main beam L1, the main beam L1 is inclined from the direction perpendicular to the straight line L0. By sequentially providing the delay time in this way, an angle can be given to the direction of the synthesized ultrasonic wave.

  The above is the linear scan method. As described above, the sector scan method in which the position of the drive element group is fixed and only the flaw detection refraction angle β is scanned to obtain a fan-shaped cross-sectional view, or a plurality of DDF, etc. Other flaw detection methods may be used in which the ultrasonic element is controlled by delay time control.

  FIG. 5 is a graph showing temporal changes in a composite signal (synthetic echo signal) of an echo signal that is a reception signal of the ultrasonic element 11 of the ultrasonic flaw detector according to the present embodiment. The horizontal axis represents time, and the vertical axis represents the vibration intensity of a combined waveform (synthetic echo) of an ultrasonic wave that is a received wave (echo). The first half of the time change shows propagation in the acoustic propagation medium 5, and the second half shows propagation in the inspection object 1.

  The imaging unit 33 calculates the sound ray that the ultrasonic main beam L1 propagates from the center of the drive element group based on the relative position relationship between the ultrasonic array probe 10 and the inspection target 1 and the shape of the inspection target 1. The intensity of the synthesized signal is plotted in the flaw detection space area of the inspection object 1 in accordance with the sound ray. By sequentially scanning the drive element group, a contour diagram of the signal intensity in the flaw detection space region or a flaw detection image is generated. The calculation result in the imaging unit 33 and information for contour diagram generation are stored in the signal processing information storage unit 41.

  FIG. 6 is a conceptual diagram showing a case where there is a defect in the flaw detection space region. This is a case where the defect 2 exists in the inspection object 1. In this imaging, the vibration amplitude or the square of the vibration amplitude is replaced with luminance.

  Imaging is a method generally called B-scan or S-scan. This image is reconstructed based on a refraction angle or a flaw detection refraction angle corresponding to a flaw detection condition such as an incident condition of ultrasonic waves to an inspection object during flaw detection. The following examples will be described using B-scan.

  As shown in FIG. 6, when there is an acoustic propagation medium 5 between the ultrasonic array probe 10 and the inspection object 1, the propagation position can also be imaged. For example, in the case of water, the propagation velocity in the acoustic propagation medium 5 is about 1500 m / second. In addition, when the material of the inspection object 1 is, for example, iron, the propagation speed in the inspection object 1 is about 5900 m / sec.

  The dimensions of the acoustic propagation medium 5, the incident angle α, and the flaw detection refraction angle β are known, and the propagation speed of the ultrasonic waves in the acoustic propagation medium 5 and the inspection object 1 are also known. Therefore, each time relating to the composite waveform has a one-to-one correspondence with the propagation position in the acoustic propagation medium 5 and the propagation position in the inspection object 1 in the flaw detection space region. Can be replaced with a position.

  FIG. 7 shows the imaging result of the flaw detection space area when there is a defect in the flaw detection space area. In the case of B-scan, the imaging unit 33, as described above, determines the intensity of the ultrasonic signal in the process of ultrasonic wave propagation in the plane parallel to the ultrasonic elements 11 in the ultrasonic array probe 10 in terms of luminance. It is indicated by change. A portion indicated by Ed in FIG. 7 corresponds to a defect.

  FIG. 8 is a conceptual diagram showing a case where there is a weld in addition to a defect in the flaw detection space region. FIG. 9 shows the imaging result of the flaw detection space area in this case. The portion indicated by Ed in FIG. 9 corresponds to the defect 2. On the other hand, the portion indicated by En corresponds to the welded portion 3. As described above, it is very difficult to distinguish the defect 2 from the welded portion 3 at first glance.

  In the flaw detection space region, the extraction unit 34 shown in FIG. 1 has an intensity of a synthesized echo obtained by synthesizing an echo as a received wave based on a synthesized signal or an imaging result (or exceeds a prescribed intensity). ) Region (echo region) is extracted as a significant echo region. The threshold value of the predetermined intensity can be set based on experience such as an echo intensity distribution in a test using a test body whose internal state is known.

  FIG. 10 is a first image for explaining extraction of a significant echo area from the imaging result of the flaw detection space area in the ultrasonic flaw detection method according to the first embodiment, and FIG. , (B) shows after extraction of the significant echo area. In this way, a threshold value is provided and all echoes less than that are erased.

  FIG. 11 is a second image for explaining extraction of a significant echo area from the imaging result of the flaw detection space area in the ultrasonic flaw detection method according to the first embodiment, and (a) is before extraction of the significant echo area. , (B) shows after extraction of the significant echo area. This also sets a threshold value and erases all echoes less than that.

  The intensity distribution calculating unit 35a as the feature amount calculating unit 35 illustrated in FIG. 1 calculates the luminance of the image imaged by the imaging unit 33, that is, the intensity distribution at each position of the synthesized signal. The intensity distribution change calculation unit 36a as the feature amount change calculation unit 36 calculates a change in intensity distribution corresponding to a change in flaw detection conditions.

  Let EIj be the echo intensity in a certain echo area Ej. At this time, j is a natural number and represents an index of an echo area in a certain flaw detection space area. The intensity of the synthesized echo can be expressed, for example, by the brightness in the imaged state. The luminance of each point in the echo area of the index j is set in proportion to the amplitude of the ultrasonic vibration at that point or the square of the amplitude. The echo intensity EIj of the echo area Ej of the index j is defined by luminance addition, addition average, peak value, or other representative value at each point in the echo area Ej. Since the echo intensity EIj changes depending on the flaw detection conditions such as the flaw detection refraction angle β and the focal position, the flaw detection conditions θ are expressed as the echo intensity EIj (θ) in each flaw detection condition.

  FIG. 12 is an image of an echo intensity distribution by imaging the flaw detection space region when the flaw detection refraction angle β is changed in the ultrasonic flaw detection method according to the first embodiment. (B) shows the case where β is 30 °, and (c) shows the case where β is 40 °. That is, this is a case where the flaw detection condition is the flaw detection refraction angle. In FIG. 12, E1 and E2 are displayed as echo areas. When the flaw detection refraction angle β is increased from 20 ° to 40 °, the echo intensity corresponding to the representative value of luminance decreases.

  FIG. 13 is a graph showing an example of changes in echo intensity when the flaw detection refraction angle β is changed in the ultrasonic flaw detection method according to the first embodiment. The horizontal axis represents the flaw detection refraction angle β as the flaw detection condition θ, and the vertical axis represents the echo intensity EI of the echo area as the feature amount. Curves E1 and E2 correspond to echo areas E1 and E2 in FIG. 12, respectively.

  When the flaw detection refraction angle β changes continuously in increments of 1 ° from 20 ° to 40 °, θ has a total of 21 patterns from 0 to 20, and an echo for a change in the flaw detection refraction angle β as the flaw detection condition θ. The change in the intensity EIj (θ) is represented by a graph as shown in FIG. Thus, since the change tendency with respect to the change in the flaw detection condition θ is clearly different between E1 and E2, it can be recognized that the origin of the significant echo areas extracted in these two echo areas is different.

  The display unit 60 displays the change in echo intensity with respect to the change in the flaw detection condition θ calculated by the intensity distribution change calculation unit 36a. The display unit 60 further detects flaws such as a composite signal of ultrasonic echoes, imaging results, coordinates of the ultrasonic array probe 10 and relative position to the inspection object 1, delay time, focal depth, flaw detection refraction angle β, and the like. The condition θ may be further displayed.

  The control calculation unit 50 controls the transmission / reception unit 20, the calculation unit 30, the storage unit 40, and the display unit 60, and aims at matching the timing among them.

  FIG. 14 is a flowchart showing a procedure in the ultrasonic flaw detection method according to the first embodiment. First, the ultrasonic array probe 10 is installed on the inspection object 1 (step S01). Next, the delay time calculation unit 31 calculates a delay time according to the flaw detection conditions (step S02). In accordance with the delay time on the transmission side, ultrasonic waves are sequentially transmitted from each ultrasonic element 11 (step S03).

  Next, the signal synthesizer 32 synthesizes the waveform received by the ultrasonic element 11 according to the delay time on the receiving side, and derives a synthesized waveform (step S04). Next, the imaging unit 33 creates an image by imaging based on each synthesized waveform data (step S05). Next, it is determined whether or not necessary scanning has been completed (step S06). The determination is made, for example, as to whether or not all the drive element groups have been completed. If not completed (NO in step S06), step S02 and subsequent steps are repeated.

  If it is determined that the scanning has been completed (YES in step S06), the extraction unit 34 performs an extraction process (step S07). Next, the intensity distribution calculation unit 35a which is the feature amount calculation unit 35 calculates the intensity distribution. Further, the intensity distribution change calculation unit 36a, which is the feature amount change calculation unit 36, calculates a change in the intensity distribution, which is a feature amount, with respect to a change in the flaw detection conditions (step S08). The display unit 60 displays the change in the intensity distribution, which is the change in the feature value, using the flaw detection condition as a parameter. Alternatively, a change in intensity with respect to a change in flaw detection conditions is displayed for each specific portion in the form of a graph with the flaw detection condition on the horizontal axis and the intensity on the vertical axis (step S09). Next, based on the change in intensity with respect to the change in the flaw detection conditions, the defect is evaluated for evaluation (step S10).

  As shown in FIG. 13, since the change tendency of the echo intensity EI as the feature quantity with respect to the change of the flaw detection refraction angle β as the flaw detection condition θ is clearly different between E1 and E2, the two echo areas are extracted. As described above, it can be recognized that the derived significant echo area has a different origin.

  For example, if the echo intensity EI measured under each flaw detection condition has no dependency on the flaw detection condition or has a small dependency on the flaw detection condition, it is a noise with a large uncertain factor, and there is a dependency on the flaw detection condition. The assumed E2 is assumed to be a defect that is a stable scatter source. Thus, by extracting a region having a high echo intensity, changing the flaw detection conditions, and investigating the change tendency, it is possible to determine that E1 is noise and E2 is defect echo.

  In addition, although the signal of E2 described the example in which the signal of E2 decreases monotonically after taking the maximum value after monotonously increasing as the flaw detection refraction angle β changes from 20 ° to 40 °, If it can be determined that the relationship between the flaw detection refraction angle and the echo intensity is significant, such as monotonously decreasing or increasing, depending on the shape and inclination of the defect, it is possible to determine the defect as an echo.

  FIG. 15 is a graph for explaining an example of determination contents of the presence / absence of a defect in the defect determination unit. The horizontal axis represents the flaw detection refraction angle β as the flaw detection condition, and the vertical axis represents the echo intensity EI as the feature amount.

  This example is a case where the echo intensity EI monotonously increases and then decreases monotonously after taking a maximum value with respect to the increase in the flaw detection refraction angle β. The flaw detection refraction angle that gives the maximum value Em of the echo intensity is set as a reference angle βm as a reference flaw detection condition. The reference angle βm is a reference for flaw detection conditions in the determination.

  Now, the flaw detection refraction angles that give the echo intensity Ed that the echo intensity is reduced from the maximum value Em by a value for determination feature amount change ΔEd, for example, 3 dB or 6 dB, are βd1 and βd2 (where βd1 <βd2 ). If the flaw detection refraction angles βd1 and βd2 are within a predetermined width, the echo is determined to be a defect echo.

Specifically, β1, β2, β3, and β4 (β1 <β2 <β3 <β4) are expressed by the following formulas (1) to (1) based on two determination flaw detection condition change widths Δβ1 and Δβ2 having predetermined values. It sets with Formula (4). However, 0 <Δβ1 <Δβ2.
β1 = βm−Δβ2 (1)
β2 = βm−Δβ1 (2)
β3 = βm + Δβ1 (3)
β4 = βm + Δβ2 (4)

Here, if the following expressions (5) and (6) hold, the echo is determined to be a defective echo.
β1 <βd1 <β2 (5)
β3 <βd2 <β3 (6)

For example, if the determination feature amount change width ΔEd is 3 dB and the determination flaw detection condition change widths Δβ1 and Δβ2 are 5 ° and 15 °, respectively, the refractive flaw detection angle β at which the echo intensity decreases by 3 dB from the peak value is set to βd1, βd2. (Βd1 <βd2). At this time, if the following equations (7) and (8) hold, the echo is determined to be a defect echo.
βm-15 ° <β1 <βm-5 ° (7)
βm + 5 ° <β2 <βm + 15 ° (8)

  The above is a case where the echo intensity EI monotonously increases and increases monotonously after taking a maximum value with respect to the increase in the flaw detection refraction angle β, but the echo intensity EI decreases monotonously with respect to the increase in the flaw detection refraction angle β. Even when the value monotonously increases after taking the minimum value after the decrease, the same determination can be made with the minimum value Emin of the echo intensity and the flaw detection refraction angle at this time as the reference angle βmin as a reference flaw detection condition.

  The same method can be used when the echo intensity EI decreases monotonously with an increase in the flaw detection refraction angle β. Specifically, when the angle region of the flaw detection refraction angle β is βm to βn, the maximum value Em of the echo intensity is taken at the reference angle βm as the reference flaw detection condition. It is assumed that the change width ΔEd and the determination flaw detection condition change width are Δβ1 and Δβ2 (where Δβ1 <Δβ2). Further, the flaw detection refraction angle β that gives the echo intensity Ed that decreases by the determination feature amount change width ΔEd from the maximum value Em of the echo intensity is assumed to be βd.

At this time, if the following equation (9) holds, the echo is determined to be a defective echo.
βm + Δβ1 <βd <βm + Δβ2 (9)

  A similar method can be used when the echo intensity EI increases monotonously with respect to the increase in the flaw detection refraction angle β. The determination may be made based on the minimum value of the echo intensity. That is, when the angle region of the flaw detection refraction angle β is from βmin to βn, the flaw detection refraction angle at which the echo intensity has the minimum value Emin is set as the reference angle βmin as the reference flaw detection condition. For example, it is assumed that the increase width of the echo intensity is the determination feature amount change width ΔEd, and the determination flaw detection condition change width is Δβ1 and Δβ2 (where Δβ1 <Δβ2). Further, the flaw detection refraction angle β that gives the echo intensity Ed that increases by the determination feature amount change width ΔEd from the minimum value Em of the echo intensity is assumed to be βd.

At this time, if the following equation (9) holds, the echo is determined to be a defective echo.
βmin + Δβ1 <βd <βmin + Δβ2 (10)

  As described above, the defect determination unit 37 determines whether or not the defect echo is based on the determination formula corresponding to the pattern of change in the echo intensity EI as the feature amount with respect to the flaw detection refraction angle β that is the flaw detection condition. Note that the determination parameters such as the determination feature amount change width ΔEd and the determination flaw detection condition change widths Δβ1 and Δβ2 used in the above examples are stored in the parameter storage unit 42 of the storage unit 40. The parameter storage unit 42 stores the determination parameter input from the input unit 70.

  These determination parameters include, for example, whether the change in the echo intensity EI as the characteristic amount with respect to the flaw detection refraction angle β, which is a flaw detection condition, takes a maximum value or a minimum value, is monotonously increased, or is monotonously decreased. Different patterns may be used. Further, based on information on the inspection target part such as the material to be inspected or the history received by the inspection target, an empirically more appropriate one can be used as the determination parameter.

  In the above cases, the case where the flaw detection condition is the flaw detection refraction angle is shown as an example, but also in the case of the change in the feature amount with respect to the other flaw detection conditions, the same method is used to determine whether or not it is a defect echo. be able to.

  FIG. 16 is a flowchart showing a determination procedure in the ultrasonic flaw detection method. As shown in FIG. 14, the intensity distribution change calculation unit 36a, which is the feature amount change calculation unit 36, calculates a change in the intensity distribution (step S08), and the display unit 60 performs the flaw detection condition on the horizontal axis, for example, for each specific part. Then, it is displayed as a change in intensity with respect to a change in flaw detection conditions in the form of a graph with the vertical axis indicating the intensity (step S09). Thereafter, as a determination evaluation step S10, it is determined whether or not each specific portion is a defect echo. The detailed procedure of determination evaluation step S10 is shown below.

  First, the defect determination unit 37 selects a change pattern (step S11). In other words, for example, a pattern in which the feature value monotonously increases after an increase in flaw detection conditions, then reaches a maximum value, and then decreases monotonously, or a pattern in which the feature amount decreases monotonously with an increase in flaw detection conditions. Are classified based on the data for graph creation given to the display unit 60 by the feature amount change calculation unit 36.

  Next, the defect determination unit 37 reads a determination parameter corresponding to the divided pattern from the parameter storage unit 42 (step S12). At this time, if information on the inspection target portion such as the material to be inspected or the history of the inspection target is acquired via the input unit 70, an appropriate determination parameter is selected according to the information. .

  Next, the defect determination unit 37 determines a reference flaw detection condition based on the graph creation data (step S13). For example, with respect to an increase in flaw detection conditions, a flaw detection condition that gives the maximum feature value is set as the reference flaw detection condition if the pattern has a maximum value after the feature value monotonously increases and then decreases monotonously.

  Next, the defect determination unit 37 uses the selected determination parameter to determine whether or not the portion of interest is due to a defect echo from the graph creation data, for example, by the method shown in FIG. (Step S14). The defect determination unit 37 outputs the determination result to the display unit 60, and the display unit 60 displays the determination result (step S15).

  As described above, the present embodiment displays the echo intensity change with respect to the change in the flaw detection refraction angle, so that on the ultrasonic flaw detection such as the welded part, the defect echo (the superflect reflected by the defect to be inspected) in the noisy object. It is possible to discriminate between reflected waves of sound waves and noise.

  FIG. 17 is a graph showing an example of a change in echo intensity when the focal depth F is changed in the modification of the ultrasonic flaw detection method according to the first embodiment. In this embodiment, the flaw detection angle is changed. Of course, what is changed is not limited to the flaw detection angle. For example, as shown in FIG. 17, the flaw detection conditions such as the focus position are changed. A change in echo intensity may be displayed.

[Second Embodiment]
FIG. 18 is a block diagram showing a configuration of an ultrasonic flaw detector according to the second embodiment. The second embodiment is a modification of the first embodiment. In the present embodiment, a center position calculation unit 35 b as the feature amount calculation unit 35 is included, and a center position change calculation unit 36 b as the feature amount change calculation unit 36 is included. That is, in the first embodiment, the feature amount is the echo intensity, but in this embodiment, the feature amount is the center position of the echo area.

  The center position (echo center position) of the echo area in a certain echo area Ej is represented by EPj. At this time, j is a natural number and represents an echo index in a certain flaw detection space region. The echo center position is represented by (Xj, Zj) for a two-dimensional flaw detection image and (Xj, Yj, Zj) for a three-dimensional coordinate. The center position of the echo area Ej is used as the echo center position. However, if the change corresponding to the change in the flaw detection condition can be confirmed as the feature amount, it is not always necessary to be at the center of the echo area Ej. For example, the coordinates at which the combined echo has the maximum intensity among the respective points in the echo area Ej may be used, or the center of gravity of a pixel group exceeding a certain threshold value may be used, and the maximum values of X, Y, and Z respectively. Alternatively, a minimum value, a center value, or the like may be used. In other words, it may be anything that is uniquely determined by specific logic.

  The echo center position under each flaw detection condition is expressed as EPj (θ), and the coordinates are expressed as Xj (θ), Yj (θ), and Zj (θ).

  For example, an example in which the flaw detection condition θ is a flaw detection refraction angle β is shown. FIG. 19 is an image showing an example of a change in the center position of the echo area in the flaw detection space area when the flaw detection refraction angle β is changed in the ultrasonic flaw detection method according to the second embodiment. β is 20 °, (b) is when β is 30 °, and (c) is when β is 40 °. A broken line represents the echo center position.

  FIG. 20 is a graph showing an example of a change in the center position of the echo area in the flaw detection space area when the flaw detection refraction angle β is changed in the ultrasonic flaw detection method according to the second embodiment. When β is continuously changed from 20 ° to 40 °, for example, in increments of 1 °, θ has a total of 21 patterns from 0 to 20, and the Xj (θ) change in the echo center position EPj (θ) is It is represented by a schematic diagram as shown in FIG.

  As the flaw detection refraction angle β is increased, that is, in FIG. 19, as the flaw detection condition θ is increased, the position of the echo region E1 is largely moved or is discontinuous. On the other hand, the position of the echo area E2 has not moved significantly. When this tendency is used, for example, E1 whose center position largely changes depending on the flaw detection conditions is estimated to be noise inherent to the material. On the other hand, E2 whose center position does not change much even if flaw detection conditions are changed is presumed to be a stable scatter source defect. Thus, it is possible to determine that E1 is noise and E2 is defect echo.

[Third Embodiment]
FIG. 21 is a block diagram showing a configuration of an ultrasonic flaw detector according to the third embodiment. The third embodiment is a modification of the first embodiment. In this embodiment, it has the luminance value frequency distribution calculation part 35c as the feature-value calculation part 35, and has the luminance value frequency distribution change calculation part 36c as the feature-value change calculation part 36. That is, in the present embodiment, the luminance value at each pixel in the flaw detection space region is used as the feature amount.

  FIG. 22 shows the frequency of the luminance value (that is, the intensity of the synthesized echo) at each pixel (each point) in the flaw detection space region when the flaw detection refraction angle β is changed in the ultrasonic flaw detection method according to the third embodiment. It is an example of a change of distribution, Comprising: It is a graph which shows the case of noise. Here, the frequency distribution of luminance values is a distribution of the frequency of appearance of luminance values for each pixel in the image area of the echo area of interest in the image area. FIG. 23 shows the frequency of the luminance value (that is, the intensity of the synthesized echo) at each pixel (each point) in the flaw detection space area when the flaw detection refraction angle β is changed in the ultrasonic flaw detection method according to the third embodiment. It is an example of a change of distribution, Comprising: It is a graph which shows the case of a defect.

  Thus, for example, noise whose position and intensity are easily affected by the beam direction tends to vary irregularly as E1. On the other hand, it is possible to estimate that the variation amount of the defect echo, which is a relatively stable scatter source, changes stably as seen in E2.

  For comparison of the change tendency at this time, correlation amount calculation, peak number, peak position, offset amount, etc. can be compared, smoothing of graph by filter, approximation using Gaussian function and exponential logarithmic function superposition, etc. To reduce the calculation load.

  In the first to third embodiments, the feature amounts are set as the echo intensity, the center position of the echo area, and the luminance value in each pixel in the flaw detection space area. Regarding the amount, various kinds of information obtained from the received ultrasonic waves can be used, and information that can be these feature amounts can be used in appropriate combination.

[Fourth Embodiment]
FIG. 24 is a block diagram showing a configuration of an ultrasonic flaw detector according to the fourth embodiment. The fourth embodiment is a modification of the first embodiment, and the calculation unit 30 further includes an integrated calculation unit 38. The integration calculation unit 38 performs integration processing using an arbitrary plurality of flaw detection images obtained as a result of the processing by the imaging unit 33, and obtains an integrated image with a higher SN ratio. The contents of integration are described below.

  FIG. 25 is a graph showing changes in echo intensity when the flaw detection refraction angle β is changed. One flaw detection image generated by the imaging unit 33 is obtained for each flaw detection condition (for example, flaw detection refraction angle β). Here, when selecting a plurality of flaw detection images, they can be selected from arbitrary flaw detection conditions, but may be selected with reference to flaw detection conditions as shown in FIG. Although an example in which the flaw detection condition is the flaw detection refraction angle β will be described here, other flaw detection conditions such as a focal depth may be used. The integrated range is, for example, a range from βs to βe as shown in FIG. In this case, all values in this range may be used for integration, or only a plurality of points may be thinned out.

  FIG. 26 is a conceptual explanatory diagram for explaining integration. When the flaw detection refraction angle as a flaw detection condition is in the range of βs to βe, (a) is the flaw detection refraction angle βs, (b) is the flaw detection refraction angle βe, (c) is the integrated result. Show.

  Integration is performed by superimposing feature quantities in a plurality of flaw detection images at each position to be inspected. As a specific method of integration, any method such as addition average or sum of squares may be used. When the flaw detection refraction angle is sequentially increased from βs to βe, the range covered by the ultrasonic wave incident when the flaw detection refraction angle shown in (a) is βs, and the flaw detection refraction angle shown in (b) is βe. The range covered by the ultrasonic waves that are sometimes incident is an area surrounded by a thick line in (c), which is displayed as an integrated image area. This integrated image area is an area covered by any ultrasonic wave having a flaw detection refraction angle of not less than βs and not more than βe.

  For example, taking the case shown in FIG. 25 as an example, in the case of the noise indicated by the broken line E1, the echo intensity EI as the feature amount changes greatly due to the change in the flaw detection refraction angle β as the flaw detection condition. For this reason, for example, the addition average value in the case of the addition average becomes smaller than the addition average value of the defect echo indicated by the solid line E2 that does not vary so much due to the change in the flaw detection refraction angle β. In this way, the SN ratio increases due to the integration.

  FIGS. 27A and 27B are comparative diagrams for explaining the effect of integration. FIG. 27A shows a case where integration is not performed, and FIG. 27B shows a case where integration is performed. In the case of only one angle shown in (a), the SN ratio is extremely small, and the image is substantially incapable of discriminating between defects and noise. On the other hand, the integrated image shown in (b) is an integrated image of six, and an integrated image having a high S / N ratio that can clearly identify defects is obtained.

  In general, the sensitivity varies depending on the flaw detection refraction angle β. Therefore, if the dependence of the sensitivity on the flaw detection angle β is confirmed in advance and the sensitivity data is acquired, the feature values of the flaw detection image for each flaw detection angle are calibrated and integrated. Can do. The sensitivity calibration value may be obtained by multiplying each flaw detection image by an angle-dependent sensitivity calibration value as a coefficient or adding it as an offset value. The sensitivity also changes depending on the frequency of the ultrasonic waves. Therefore, when a plurality of frequencies are used, integration may be performed after the sensitivity calibration of the flaw detection image for each frequency is similarly performed.

  Further, in the process of generating a flaw detection image, there may be a case where rattling occurs for each pixel due to missing pixels or the like. In order to suppress such a situation, a smoothing process such as applying a Gaussian filter may be provided.

  As described above, by performing the integration according to the present embodiment, it is possible to more reliably determine the defect echo and the noise.

[Fifth Embodiment]
FIG. 28 is a block diagram showing a configuration of an ultrasonic flaw detector according to the fifth embodiment. This embodiment is a modification of the first embodiment. Instead of the switching unit 22, the delay time calculating unit 31, and the signal combining unit 32 in the first embodiment, the fifth embodiment includes a switching unit 22a, a delay time calculating unit 31a, and a signal combining unit 32a. Each content will be described later.

  FIG. 29 is a flowchart showing a procedure in the ultrasonic flaw detection method according to the fifth embodiment. This embodiment is a modification of the first embodiment. Steps having the same contents as those in the first embodiment are given the same numbers as those in the first embodiment. Hereinafter, steps different from those of the first embodiment will be described.

  FIG. 30 is a block diagram illustrating states of ultrasonic transmissions in the ultrasonic flaw detection method according to the fifth embodiment. Among the ultrasonic elements 11 included in the ultrasonic array probe 10, the elements to be used are N elements of the first element to the Nth element. The ultrasonic elements 11 to be used may be all the ultrasonic elements 11 included in the ultrasonic array probe 10.

  After step S01, the switching unit 22a of the transmission / reception unit 20 transmits ultrasonic waves one by one for all the ultrasonic elements 11 to be used, that is, the first element to the Nth element (step S11). . 30A shows transmission from the first element, FIG. 30B shows transmission from the second element, and FIG. 30C shows transmission from the Nth element. All the ultrasonic elements 11 including the ultrasonic elements 11 themselves receive the ultrasonic waves transmitted from each. The signal processing information storage unit 41 of the storage unit 40 stores the waveforms received by all the ultrasonic elements 11 every time transmission is performed from the first element to the Nth element.

  Next, the transmission / reception unit 20 determines whether or not transmission for all the ultrasonic elements 11 has been completed (step S12). If it is determined that it has not been completed (NO in step S12), step S11 is repeated. If it is determined that all the processes have been completed (YES in step S12), the process proceeds to the next step.

  Next, the delay time calculation unit 31a serves as a reference for the time from transmission to reception for each combination of the transmitted ultrasonic element 11 and the received ultrasonic element 11 for each portion obtained by dividing the inspection object 1. An increase / decrease with respect to time (reference time) is calculated as a delay time (step S13). Each waveform data obtained in this way is synthesized (step S14).

  FIG. 31 is a waveform diagram showing a part of an echo waveform (received waveform) due to transmission of ultrasonic waves in the ultrasonic flaw detection method according to the fifth embodiment. In order to simplify the description, a case where the number of elements is three as shown in FIG. 31 will be described. Now, the case where the portion obtained by dividing the inspection object 1 is a defect 2 is shown. That is, there are nine combinations, such as when transmitting from the first element and reaching the defect 2 and receiving at the first element, or when transmitting from the third element and reaching the defect 2 and receiving at the third element.

  First, the waveform as it is without considering the delay time is called a basic waveform. The ultrasonic waves transmitted from the first element and received by the first element to the third element are denoted as Uf1,1, Uf1,2, Uf1,3, respectively. The ultrasonic waves transmitted from the second element and received by the first element to the third element are denoted as Uf2,1, Uf2,2, Uf2,3, respectively. Similarly, ultrasonic waves transmitted from the third element and received by the first element to the third element are denoted as Uf3, 1, Uf3, 2, and Uf3, 3, respectively.

  FIG. 32 is a waveform diagram for explaining delay times during transmission and reception of ultrasonic waves. FIG. 32 is based on the time required for a round trip when the first element receives an echo transmitted from the first element, reaching the defect 2 and reflected by the defect 2.

  As shown in FIG. 31, the distance from the second element to the defect 2 is shorter and the distance from the third element to the defect 2 is shorter than the distance from the first element to the defect 2. Therefore, in order for the ultrasonic waves from the respective elements to reach the defect 2 at the same time, it is necessary to delay the time of transmission from the second element from the time of transmission from the first element. Further, it is necessary to further delay the time point of transmission from the third element.

  Similarly, on the return path, the distance from the defect 2 to the second element is shorter and the distance from the defect 2 to the third element is shorter than the distance from the defect 2 to the first element. As a result, in order to superimpose the respective waves, it is necessary to delay the reception time of the second element. In addition, it is necessary to further delay the time of reception of the third element.

  The transmission delay time and the reception delay time shown in FIG. 32 are the delay times derived as described above. FIG. 33 is a waveform diagram showing a composite waveform of echoes. Since the arrival time is matched in the delay time calculation unit 31a, the synthesis in the signal synthesis unit 32a can calculate a synthesized waveform under a large SN ratio.

  In the present embodiment, by performing transmission once for each ultrasonic element 11, the flaw detection conditions in which the flaw detection refraction angle β, the focus depth, and the like are changed by the signal processing in the calculation unit 30 thereafter are covered. Can be obtained. Specifically, if a delay time according to the purpose is set by the delay time calculation unit 31a, a synthesized waveform can be obtained by the signal synthesis unit 32a.

  That is, the on-line inspection for the inspection object 1 is actually performed continuously because only the transmission for each ultrasonic element 11 is performed once, and the calculation for each time is not necessary. be able to. Subsequent processing can be performed off-line, and the time for on-site inspection work can be greatly reduced.

[Sixth Embodiment]
FIG. 34 is a block diagram showing a configuration of an ultrasonic flaw detector according to the sixth embodiment. This embodiment is a modification of the first embodiment. The calculation unit 30 of the ultrasonic flaw detector 100 according to the sixth embodiment includes an inspection target surface shape calculation unit 39.

  The inspection target surface shape calculation unit 39 acquires the surface shape of the inspection target 1 when the surface of the inspection target 1 has a complicated curved surface or uneven surface instead of a flat surface. Specifically, the surface shape may be visualized by an aperture synthesis method using a basic waveform, and the surface shape of the inspection object 1 may be obtained from the result. Alternatively, the surface shape may be read from the design drawing. Alternatively, the inspection target surface shape measuring means such as a camera or a laser distance meter may be attached to the ultrasonic array probe 10 or separately provided in the vicinity thereof. Once the surface shape is obtained, it can be used repeatedly for calculating the delay time.

[Other Embodiments]
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.

  Moreover, you may combine the characteristic of each embodiment. For example, the features of the fourth embodiment may be combined with the features of other embodiments. Alternatively, the features of the sixth embodiment may be combined with the first to fourth embodiments. Alternatively, the fifth and sixth embodiments may be further combined.

  Furthermore, these embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Inspection object, 2 ... Defect, 3 ... Welding part, 5 ... Acoustic propagation medium, 10 ... Ultrasonic array probe, 11 ... Ultrasonic element, 20 ... Transmission / reception part, 21 ... Potential difference application part, 22, 22a ... Switching , 23... AD converter, 30... Arithmetic unit, 31, 31 a... Delay time arithmetic unit, 32, 32 a... Signal synthesizer, 33 ... imaging unit, 34 ... extraction unit, 35 ... feature quantity calculation unit, 35 a. Intensity distribution calculator, 35b ... Center position calculator, 35c ... Luminance value frequency distribution calculator, 36 ... Feature value change calculator, 36a ... Intensity distribution change calculator, 36b ... Center position change calculator, 36c ... Luminance value frequency Distribution change calculation unit, 37 ... Defect determination unit, 38 ... Integrated calculation unit, 39 ... Inspection target surface shape calculation unit, 40 ... Storage unit, 41 ... Signal processing information storage unit, 42 ... Parameter storage unit, 50 ... Control calculation unit , 60 ... display part, 70 ... input part 100 ... ultrasonic flaw detector

Claims (11)

An ultrasonic array probe having a plurality of ultrasonic elements arranged in parallel to transmit ultrasonic waves to the inspection object and receive ultrasonic waves reflected from the inspection object;
A potential difference applying unit capable of applying a potential difference that causes vibration in the ultrasonic element;
A delay time calculator that calculates a delay time for shifting the timing at which the ultrasonic element transmits and receives the ultrasonic wave;
A switching unit that switches between a state in which the potential difference applying unit applies a potential difference to the ultrasonic element and a state in which the potential difference applying unit does not apply a potential difference to the ultrasonic element;
A feature amount calculation unit that calculates a feature amount related to a synthesized echo obtained by combining the received wave received by the ultrasonic element according to the delay time;
A feature amount change calculation unit for calculating a change in the feature amount with respect to a change in a flaw detection condition of the ultrasonic wave on the inspection target;
A display unit for displaying the calculated feature amount change;
An ultrasonic flaw detector characterized by comprising:   The defect determination unit for determining whether or not the defect is a defect based on the change in the feature value using a reference flaw detection condition that gives a maximum value or a minimum value of the feature value and a determination parameter. The ultrasonic flaw detector described in 1. Further comprising an integrated calculation unit that integrates feature quantities of the synthesized echo obtained by a plurality of flaw detection conditions,
The ultrasonic flaw detection apparatus according to claim 1, wherein the display unit can further display an integrated image based on the image data integrated by the integrated arithmetic unit.   The ultrasonic flaw detector according to claim 1, wherein the feature amount is an intensity of the synthesized echo.   The feature amount is a change in the center position of an echo region where the intensity of the synthesized echo exceeds a predetermined threshold value or becomes equal to or greater than the threshold value. The ultrasonic flaw detector according to claim 1.   The feature amount is a distribution of the intensity of the synthetic echo at each point in an echo area where the intensity of the synthetic echo exceeds a predetermined threshold value or is equal to or greater than the threshold value. The ultrasonic flaw detector according to any one of claims 1 to 3.   The switching unit is configured so that the ultrasonic element transmits an ultrasonic wave to the inspection target based on the delay time, and the ultrasonic element receives the ultrasonic wave from the inspection target based on the delay time. The ultrasonic flaw detection apparatus according to claim 1, wherein the application of a potential difference to each of the ultrasonic elements is switched. A signal synthesis unit;
The switching unit performs switching so that each of the ultrasonic elements sequentially transmits ultrasonic waves without the delay time,
The signal synthesizer synthesizes the received waves received by the ultrasonic elements by transmitting ultrasonic waves from the respective ultrasonic elements, shifted by the delay time corresponding to each of the received waves,
The ultrasonic flaw detector according to any one of claims 1 to 5, wherein In a data processing apparatus that processes signal data transmitted to and received by an ultrasonic array probe having a plurality of ultrasonic elements,
A delay time calculator that calculates a delay time for shifting the timing at which the ultrasonic element transmits and receives ultrasonic waves;
A switching unit that switches between a state in which the potential difference applying unit applies a potential difference to the ultrasonic element and a state in which the potential difference applying unit does not apply a potential difference to the ultrasonic element;
A feature amount calculation unit that calculates a feature amount related to a synthesized echo obtained by combining the received wave received by the ultrasonic element according to the delay time;
A feature amount change calculation unit for calculating a change in the feature amount with respect to a change in a flaw detection condition of the ultrasonic wave on the inspection target;
A display unit for displaying the calculated feature amount change;
A data processing apparatus comprising: The imaging unit creates an image inside the inspection object based on a composite waveform of the ultrasonic wave received from the ultrasonic element of the ultrasonic array probe to the inspection object; and
A feature amount calculating unit that calculates a feature amount based on the video;
A feature amount change calculating unit that calculates a change in the feature amount with respect to a change in flaw detection conditions; and
A display step for displaying a change in the feature value;
An ultrasonic flaw detection method comprising: A pattern selection step in which the defect determination unit selects a change pattern based on a calculation result in the feature amount change calculation step;
A parameter reading step in which the defect determination unit reads a corresponding parameter from a parameter storage unit based on the selected pattern;
The defect determination unit determines a reference flaw detection condition based on a calculation result in the feature amount change calculation step;
A determination step for determining whether the defect determination unit is an echo based on a defect from the calculation result in the feature amount change calculation step, the parameter, and the reference flaw detection condition;
The ultrasonic flaw detection method according to claim 10, comprising:

Images