JP7381888B2 - Ultrasonic flaw detection system and ultrasonic flaw detection method - Google Patents

Description

The present invention relates to an ultrasonic flaw detection system and an ultrasonic flaw detection method, and is particularly suitable for use in ultrasonic flaw detection of defects in a material to be detected.

Ultrasonic flaw detection is a non-destructive method for inspecting defects in materials such as square steel. As such ultrasonic flaw detection methods, there are vertical flaw detection method and oblique flaw detection method. The vertical flaw detection method is a method in which ultrasonic waves are applied in a direction perpendicular to the surface of a material to be tested inward from the surface thereof, and the reflected echoes are received. The oblique flaw detection method is a method in which ultrasonic waves are obliquely incident from the surface of a material to be tested inward toward another surface adjacent to the surface, and the reflected echoes are received.

Technologies described in Patent Documents 1 to 3 are techniques for inspecting defects inside a material to be tested using such ultrasonic flaw detection.
Patent Document 1 discloses that oblique flaw detection is performed on the surface layer of the corner between the surface adjacent to the incident surface and the opposing surface using a longitudinal wave at a refraction angle of 65 to 80 degrees, and that the refraction angle is set at a refraction angle of 40 to 50 degrees using a transverse wave. It is described that angle flaw detection is performed on the surface layer portion of the surface adjacent to the incident surface as a 90° angle, and flaw detection is performed on the surface of the material to be tested and its vicinity using surface waves. In Patent Document 1, defects detected by longitudinal waves or transverse waves and also detected by surface waves are assumed to exist near the surface, and defects detected only by longitudinal waves or transverse waves are assumed to exist under the skin.

Patent Document 2 describes oblique flaw detection near the lower corner of a surface adjacent to the ultrasonic incident surface, and detecting the ultrasonic scanning position when the reflected echo from the corner becomes the maximum. In addition, correcting the ultrasonic scanning range and flaw detection gate range so that the desired flaw detection range can be detected based on the scanning position, and performing oblique flaw detection in the corrected scanning range and flaw detection gate range. It is stated that.

Patent Document 3 describes that the inside of a material to be tested is flaw-detected using a vertical flaw detection method, the material to be flaw-tested is flaw-detected by an oblique flaw detection method, and the surface of the material to be flaw-tested is detected using surface waves. .
Patent Document 4 describes the method of obtaining surface defect information including only surface defects of a material to be tested using a surface wave flaw detection method or the like, and obtaining angle flaw detection information including flaw detection information of surface defects and surface subcutaneous defects using an oblique angle flaw detection method. It is described that a surface subcutaneous defect is extracted by subtracting surface defect information from oblique angle flaw detection information. Further, Patent Document 4 describes that water is placed in a region between an ultrasonic probe (probe) and an incident surface of a material to be tested.

Japanese Unexamined Patent Publication No. 58-216950 Japanese Unexamined Patent Publication No. 59-148860 Japanese Unexamined Patent Publication No. 59-148864 Japanese Unexamined Patent Publication No. 59-148865 Patent No. 5279090

However, the techniques described in Patent Documents 1 to 4 do not consider the state of the surface of the material to be tested or the state of the region between the ultrasonic probe and the material to be tested. For this reason, for example, noise generated when the ultrasonic incident surface (surface) is not flat or when air bubbles are generated in the water between the ultrasonic probe and the incident surface of the inspected material can be detected as a defect. There is a risk of false positive detection.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to suppress false detection when performing ultrasonic flaw detection on defects existing inside a material to be flaw-detected.

The ultrasonic flaw detection system of the present invention is an ultrasonic flaw detection system that detects defects in a material to be tested whose cross section perpendicular to the longitudinal direction is substantially rectangular by performing ultrasonic flaw detection using a phased array method. four ultrasonic probes each having a plurality of ultrasonic transducers that can be placed along the surface of the material, one ultrasonic probe placed on each of the four sides of the substantially rectangular shape; a probe ; and a defect detection means for detecting defects in the material to be tested based on reflected echoes received by the ultrasonic probe by transmitting ultrasonic waves from the ultrasonic probe to the material to be tested. and a flaw detection range when vertical flaw detection is performed using the first ultrasonic probe, which is the ultrasonic probe installed on one of the four sides of the substantially quadrangular shape, and one of the four sides of the substantially quadrangular shape. , using the second ultrasonic probe and the third ultrasonic probe, which are the ultrasonic probes installed on two sides located on both sides of the one side, to the one side of the four sides of the substantially rectangular shape. At least a portion of the flaw detection range when performing oblique flaw detection toward one opposing side overlaps with each other, and the defect detection means includes the first ultrasonic probe, the second ultrasonic probe, and when the intensity of at least two of the reflected echoes received by the third ultrasonic probe by transmitting ultrasonic waves to the flaw detection range exceeds a threshold; , it is determined that the material to be flaw-detected has a defect , and if not, it is determined that the material to be flaw-tested has no defect .

The ultrasonic flaw detection method of the present invention includes four ultrasonic probes each having a plurality of ultrasonic transducers that can be placed along the surface of a material to be tested whose cross section perpendicular to the longitudinal direction is approximately square, Ultrasonic flaw detection in which defects in the material to be flawed are detected by performing ultrasonic flaw detection using a phased array method using four ultrasonic probes arranged one on each of the four sides of the substantially rectangular shape. A defect detection step of transmitting ultrasonic waves from the ultrasonic probe to the material to be tested and detecting defects in the material to be tested based on reflected echoes received by the ultrasonic probe. , and the flaw detection range when performing vertical flaw detection using the first ultrasonic probe that is the ultrasonic probe installed on one side of the four sides of the substantially rectangle, and Among them, the second ultrasonic probe and the third ultrasonic probe, which are the ultrasonic probes installed on two sides located on both sides of the one side, are used to measure one side of the four sides of the substantially rectangular shape. At least a portion of the flaw detection range in the case of performing oblique flaw detection toward one side opposite to the flaw detection range overlaps with each other, and the defect detection step includes the first ultrasonic probe and the second ultrasonic probe. , and among the reflected echoes received by the ultrasonic probe by transmitting ultrasonic waves to the flaw detection range by the third ultrasonic probe , the intensity of at least two reflected echoes exceeds a threshold value. Preferably , it is determined that there is a defect in the material to be tested , and if not, it is determined that there is no defect in the material to be tested .

According to the present invention, it is possible to suppress false detection when performing ultrasonic flaw detection on defects existing inside a material to be flaw-detected.

It is a 1st diagram showing an example of arrangement of an ultrasonic probe and square steel. It is a 2nd diagram showing an example of arrangement of an ultrasonic probe and square steel. It is a figure which shows an example of the flaw detection range when performing vertical flaw detection with an ultrasonic probe. It is a figure which shows the 1st example of the flaw detection range when + oblique angle flaw detection is performed with an ultrasonic probe. FIG. 3 is a diagram showing a first example of a flaw detection range when performing oblique flaw detection with an ultrasonic probe. FIG. 3 is a diagram apocryphally illustrating an example of how the state of the surface area of the square steel and the state of the area between the ultrasonic probe and the square steel are not normal. It is a figure which shows the 2nd example of the flaw detection range when + oblique angle flaw detection is performed with an ultrasonic probe. FIG. 7 is a diagram showing a second example of a flaw detection range when performing oblique flaw detection with an ultrasonic probe. 3A is a diagram showing a combination of the flaw detection range shown in FIG. 3A, the flaw detection range shown in FIG. 3E, and the flaw detection range shown in FIG. 3F. FIG. It is a figure showing an example of the functional composition of a defect detection device. FIG. 3 is a diagram conceptually showing an example of a group of cross-sectional echo waveforms. It is a figure which conceptually shows an example of the relationship between the maximum echo intensity and the position of the longitudinal direction (Y-axis direction) of a square steel. 12 is a flowchart illustrating an example of a process of deriving and storing an echo intensity-position relationship. It is a flowchart explaining an example of the process which determines the presence or absence of a defect of square steel M, and outputs it. FIG. 7 is a diagram showing a specific example of the echo intensity-position relationship when vertical flaw detection is performed. FIG. 7 is a diagram showing a specific example of the echo intensity-position relationship when performing oblique flaw detection.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In this embodiment, a case will be described using as an example a case where the material to be tested whose cross section perpendicular to the longitudinal direction is substantially rectangular is a square steel. In each figure, a part of the configuration is omitted or simplified for convenience of explanation and notation. Furthermore, the XYZ coordinates shown in each figure indicate the orientation relationship in each figure. In the notation of X-Y-Z coordinates, a ● inside a circle indicates the direction from the back of the paper to the front, and an X inside a circle indicates the direction from the front of the paper. Indicates the direction towards the back.
FIG. 1 is a diagram showing an example of the arrangement of the ultrasonic probes 110a to 110d and the square steel M, and shows a cross section (XZ cross section) taken perpendicularly to the axial direction (longitudinal direction, Y-axis direction) of the square steel M. ). FIG. 2 is a diagram showing an example of the arrangement of the ultrasonic probes 110a to 110d and the square steel M, and the surface (parallel to the longitudinal direction) of the square steel M (the incident surface of the ultrasonic waves transmitted from the ultrasonic probe 110a). is a diagram seen from above.

In FIG. 1, ultrasonic probes 110a to 110d are ultrasonic probes for performing ultrasonic flaw detection using a phased array method, and are phased array probes. A phased array probe has a plurality of ultrasonic transducers that can be arranged along the surface of a material to be tested (in a direction perpendicular to both the normal direction of the surface of the material to be tested and the axial direction of the material to be tested). In the general phased array method, the timing (i.e. phase) of transmitting ultrasonic waves from each ultrasonic transducer is shifted, and the propagation direction of the ultrasonic wave and its convergence are adjusted without changing the position of each ultrasonic transducer. Change the position (focus). In this method, by changing the propagation direction of the ultrasonic wave and its convergence position (focus), both vertical flaw detection and oblique flaw detection can be performed without changing the position of each ultrasonic transducer. .

Although such a general phased array method may be used, in this embodiment, a case where ultrasonic flaw detection is performed by a volume focus phased array method will be described as an example. In the volume focus phased array method, ultrasonic waves are transmitted from all the ultrasonic transducers of the array probe at once, and then reflected echoes are received by all the ultrasonic transducers, and the signals of the reflected echoes are processed. In this embodiment, a case where ultrasonic flaw detection is performed using the volume focus phased array method described in Patent Document 5 will be described as an example. The volume focus phased array method itself is described in Patent Document 5, so a detailed explanation thereof will be omitted here.

Further, in FIG. 1, in this embodiment, holders 120a to 120d are attached to the ultrasonic probes 110a to 110d. Holders 120a-120d have hollow regions. The ultrasonic wave transmission surfaces of the ultrasonic probes 110a to 110d are arranged in hollow regions of the holders 120a to 120d so as to face the distal ends of the holders 120a to 120d. Furthermore, the tip sides of the holders 120a to 120d (the side in contact with the square steel M) are open.

As shown in FIG. 1, the holders 120a to 120d are moved together with the ultrasonic probes 110a to 110d so that the tips of the holders 120a to 120d come into contact with the square steel M, and water is supplied into the hollow areas of the holders 120a to 120d. do. At this time, water is individually supplied to each of the holders 120a to 120d. In this way, water is placed in the area between the ultrasonic wave transmitting surface and the square steel M in the ultrasonic probes 110a to 110d. In this embodiment, the water disposed in the region between the ultrasonic transmitting surface of the ultrasonic probes 110a to 110d and the square steel M is in a separated state (not communicating). That is, in this embodiment, local water immersion type (water column type) ultrasonic flaw detection is performed. Incidentally, a water immersion type (submersion type) ultrasonic flaw detection may be performed in which the water placed in the area between the ultrasonic transmitting surface of the ultrasonic probes 110a to 110d and the square steel M is not separated. It is preferable to perform immersion type (water column type) ultrasonic flaw detection. The reason for this will be explained later.

If the positions of the ultrasonic probes 110a to 110d in the longitudinal direction (Y-axis direction) of the square steel M are the same, it is necessary to transmit and receive ultrasonic waves from the ultrasonic probes 110a to 110d in order. Further, in this embodiment, ultrasonic waves are transmitted and received from the ultrasonic probes 110a to 110d at each of a plurality of positions in the longitudinal direction of the square steel M. Therefore, when transmitting and receiving ultrasonic waves from the ultrasonic probes 110a to 110d in order, in order to secure time for transmitting and receiving the ultrasonic waves, the conveyance speed of the square steel M must be reduced or the conveyance of the square steel M must be temporarily stopped. There must be. In contrast, in this embodiment, as shown in FIG. 2, the positions of the ultrasonic probes 110a to 110d in the longitudinal direction (Y-axis direction) of the square steel M are different from each other. In this way, ultrasonic waves can be continuously transmitted and received from the ultrasonic probes 110a to 110d. Therefore, it is possible to prevent the conveyance of the square steel M from being delayed, which is preferable.

Next, an example of the flaw detection range in the square steel M will be explained.
FIG. 3A is a diagram showing an example of a flaw detection range when performing vertical flaw detection with the ultrasonic probe 110a. FIG. 3B is a diagram illustrating an example of a flaw detection range when + oblique angle flaw detection (first oblique angle flaw detection) is performed using the ultrasonic probe 110a. FIG. 3C is a diagram illustrating an example of a flaw detection range when performing -angle flaw detection (second angle flaw detection) using the ultrasonic probe 110a. Here, the oblique flaw detection to the right in the ultrasonic transmission direction is defined as + oblique flaw detection, and the oblique flaw detection to the left is defined as - bevel flaw detection.

In FIG. 3A, a flaw detection range 311 is a flaw detection range when vertical flaw detection is performed using the ultrasonic probe 110a. When performing vertical flaw detection, a slight dead zone exists near the opposing surface (surface P3 in the examples shown in FIGS. 3A to 3C) that faces the ultrasonic incident surface (surface P1 in FIG. 3A). Therefore, the flaw detection range 311 and the surface P3 are slightly apart. The distance between the ultrasonic wave incident surface (plane P1 in FIG. 3A) and the flaw detection range 311 in the ultrasonic propagation direction is set in advance.

In FIG. 3B, a flaw detection range 312 is a flaw detection range when + oblique flaw detection is performed using the ultrasonic probe 110a. In FIG. 3C, a flaw detection range 313 is a flaw detection range when performing oblique flaw detection using the ultrasonic probe 110a. The distance between the ultrasonic wave incident surface (plane P1 in FIG. 3A) and the flaw detection ranges 312 and 313 in the ultrasonic propagation direction is set in advance.
When performing oblique flaw detection, the adjacent surfaces adjacent to the ultrasonic incident surface (surfaces P2 and P4 in the examples shown in FIGS. 3A to 3C) and the opposing surface (surface P4 in the examples shown in FIGS. 3A to 3C) ) can be detected by performing a pseudo sector scan described in Patent Document 5, for example.

3A to 3C show the flaw detection range of the ultrasonic probe 110a. The flaw detection ranges for the other ultrasonic probes 110b to 110d are determined in the same manner as the flaw detection range for the ultrasonic probe 110a. Therefore, detailed explanation thereof will be omitted here. Note that the flaw detection ranges of the ultrasonic probes 110a to 110d have the same size and shape, but differ in position.

As described in Patent Document 5, by performing vertical flaw detection, + oblique angle flaw detection, - oblique angle flaw detection, and pseudo sector scanning with each of the ultrasonic probes 110a to 110d, substantially all areas of the square steel M can be inspected. Ultrasonic flaw detection can be performed. However, the state of the ultrasound incidence surface (plane P1 in the examples shown in FIGS. 3A to 3C) and the state of the area between the ultrasound probe and the ultrasound incidence surface transmitted from the ultrasound probe are normal. It may not be. FIG. 3D is a diagram conceptually showing an example of how the state of the surface P1 of the square steel M and the state of the region between the ultrasonic probe 110a and the square steel M are not normal.

As shown in FIG. 3D, when vertical flaw detection is performed with the ultrasonic probe 110a in a state where air bubbles B exist in the region between the ultrasonic probe 110a and the surface P1, the air bubbles B cause a defect B' that does not actually exist. There is a risk that the damage will be detected. Further, there is a possibility that such bubbles B cause diffuse reflection or attenuation of the ultrasonic waves. Furthermore, even if there is a recess D in the surface P1, the recess D may cause diffuse reflection or attenuation of the ultrasonic waves.

Therefore, in the present embodiment, at least a part (all or part) of the flaw detection range by at least two of vertical flaw detection, +angle flaw detection, and -angle flaw detection, which are performed by mutually different ultrasonic probes. Set the flaw detection range so that they overlap with each other. Then, when a defect is detected in at least two flaw detection ranges that at least partially overlap, it is determined that there is a defect in the flaw detection range. On the other hand, if a defect is detected only in one of the flaw detection ranges that overlap at least in part, the defect is determined to be noise. Note that if no defect is detected in all of the flaw detection ranges that overlap at least in part, it is determined that there is no defect in the flaw detection range.

FIG. 3E shows an example of a flaw detection range when performing +angle flaw detection with the ultrasonic probe 110b, and FIG. 3F shows an example of a flaw detection range when performing -angle flaw detection with the ultrasonic probe 110d. In FIG. 3E, a flaw detection range 322 is a flaw detection range when + oblique flaw detection is performed using the ultrasonic probe 110b. In FIG. 3F, a flaw detection range 343 is a flaw detection range when -angle flaw detection is performed using the ultrasonic probe 110d. FIG. 3G is a diagram showing a state in which the flaw detection range 311 shown in FIG. 3A, the flaw detection range 322 shown in FIG. 3E, and the flaw detection range 343 shown in FIG. 3F are combined. FIG. 3G also shows flaw detection ranges 321, 331, and 341 when vertical flaw detection is performed using the ultrasonic probes 110b to 110c.

In the examples shown in FIGS. 3A to 3C and 3E to 3F, flaw detection ranges 311 to 313, 322, 343 are Set. In this case, the flaw detection range 311 when performing vertical flaw detection with the ultrasonic probe 110a overlaps with at least one of the flaw detection ranges 322 and 343. Therefore, when a defect is detected in at least two of these flaw detection ranges 311, 322, and 343, it is determined that there is a defect in the flaw detection range 311 (or its surroundings).

Although all illustrations are omitted, the flaw detection range 321 when performing vertical flaw detection with the ultrasonic probe 110b is the flaw detection range 321 when performing +angle flaw detection with the ultrasonic probe 110c, and the flaw detection range 321 when performing +angle flaw detection with the ultrasonic probe 110a. It overlaps with at least one of the flaw detection ranges 313 when performing. Therefore, when a defect is detected in at least two of these flaw detection ranges, it is determined that there is a defect in the flaw detection range 321 (or its surroundings).

Similarly, the flaw detection range 331 when performing vertical flaw detection with the ultrasonic probe 110c is the flaw detection range 331 when performing +angle flaw detection with the ultrasonic probe 110d, and the flaw detection range when performing -angle flaw detection with the ultrasonic probe 110b. Overlaps at least one of the ranges. Therefore, when a defect is detected in at least two of these flaw detection ranges, it is determined that there is a defect in the flaw detection range 331 (or its surroundings).

Furthermore, the flaw detection range 341 when performing vertical flaw detection with the ultrasonic probe 110d is the flaw detection range 312 when performing +angle flaw detection with the ultrasonic probe 110a, and the flaw detection range 312 when performing -angle flaw detection with the ultrasonic probe 110c. Overlaps at least one of the ranges. Therefore, when a defect is detected in at least two of these flaw detection ranges, it is determined that there is a defect in the flaw detection range 341 (or its surroundings).

In the examples shown in FIGS. 3A to 3C and 3E to 3F, the flaw detection ranges other than the flaw detection ranges 311, 321, 331, and 341 are set not to overlap with other flaw detection ranges.
As described above, in this embodiment, for example, the flaw detection range 311 when performing vertical flaw detection with the ultrasonic probe 110a, the flaw detection range 322 when performing oblique flaw detection with the ultrasonic probe 110b, and the flaw detection range 322 when performing oblique flaw detection with the ultrasonic probe 110d. - If a defect is detected in at least two of the flaw detection ranges 343 when performing oblique flaw detection, it is determined that there is a defect in the flaw detection range 311 (or its surroundings).

Therefore, for example, in FIG. 3G, there is a flaw detection range 311 when performing vertical flaw detection with the ultrasonic probe 110a, and a flaw detection range 322 (when performing +angle flaw detection (-angle flaw detection) with the ultrasonic probe 110b (110d)). 343), a defect may be detected both in a range different from the flaw detection range 311. In this embodiment, in order to prevent a defect from being overlooked, it is assumed that there is a defect in the flaw detection range 311 (or its surroundings) even in such a case. This also applies to the other flaw detection ranges 321, 331, and 341. However, it is not necessarily necessary to do this. For example, by specifying the position of a defect in a cross section perpendicular to the axis of the square steel M, only defects within the flaw detection ranges 311, 321, 331, and 341 can be detected.

In the examples shown in FIGS. 3A to 3C and 3E to 3F, flaw detection ranges 311 to 313, 321, 322, 331, 341, and 343 are set. That is, in this embodiment, so-called subcutaneous flaw detection is performed, and vertical flaw detection and oblique angle subcutaneous flaw detection are vertical subcutaneous flaw detection and oblique subcutaneous flaw detection, respectively.

FIG. 4 is a diagram showing an example of the functional configuration of the defect detection device 400. The defect detection device 400 is a device that performs processing for detecting defects inside the square steel M by inputting reflected echoes obtained by the ultrasonic probes 110a to 110d. The hardware configuration of the defect detection device 400 is realized, for example, by using an information processing device including a CPU, a ROM, a RAM, an HDD, a signal processing circuit, and various interfaces, or by using dedicated hardware. An example of the functions that the defect detection device 400 has will be described below. Here, it is assumed that the square steel M is transported on a transport roll in the positive direction of the Y-axis. Further, as shown in FIG. 2, it is assumed that a sensor 210 for detecting the position of the head of the square steel M is arranged on the conveyance line of the square steel M. In this embodiment, an ultrasonic flaw detection system is configured by using ultrasonic probes 110a to 110d, holders 120a to 120d, sensor 210, and defect detection device 400.

<Detection unit 401 for flaw-detected material>
The flaw-detected material detection unit 401 detects the square steel M based on the signal output from the sensor 210.

<Ultrasonic output instruction unit 402>
The ultrasonic output instruction unit 402 performs a transmission process after the beginning of the square steel M is detected by the inspection target detection unit 401, and sends a control signal for controlling the ultrasonic transmission operation to the ultrasonic probes 110a to 110d. Output.
Based on the control signal output from the ultrasound output instruction unit 402, the ultrasound transducer is excited according to the volume focus phased array method, and ultrasound is transmitted. In this embodiment, the ultrasonic probes 110a to 110d, for example, sequentially perform vertical flaw detection, +angle angle flaw detection, and -angle angle flaw detection as a process in one cycle, and repeat this process at a predetermined measurement cycle. Note that the specific configuration for transmitting ultrasonic waves from the ultrasonic probes 110a to 110d is described in Patent Document 5, so a detailed explanation thereof will be omitted.

In addition, prior to transmitting such ultrasonic waves, based on the control signal output from the defect detection device 400, the holders 120a to 120d are moved together with the ultrasonic probes 110a to 110d so that the tips of the holders 120a to 120d come into contact with the square steel M. 120a-120d are moved and water is supplied into the hollow regions of the holders 120a-120d. Note that the tips of the holders 120a to 120d are determined based on the time when the leading edge of the square steel M is detected by the sensor 210, the conveyance speed of the square steel M, and the distances Y1 to Y4 from the sensor 210 to the ultrasonic probes 110a to 110d. It can be determined whether the square steel M has reached a position where it can be contacted.

<Reflection echo acquisition unit 403>
The reflected echo acquisition unit 403 inputs reflected echo signals received by the ultrasound probes 110a to 110d when the ultrasound probes 110a to 110d transmit ultrasound, and performs reception processing. A specific configuration for receiving reflected echo signals is described in Patent Document 5, so detailed description thereof will be omitted.

<Position derivation unit 404>
The position derivation unit 404 detects the square steel M in each measurement cycle based on the measurement cycle (time) at which the leading edge of the square steel M is detected by the sensor 210, the conveyance speed of the square steel M, and the length in the longitudinal direction of the square steel M. Information indicating which position in the longitudinal direction (Y-axis direction) faces the ultrasonic probes 110a to 110d is derived. In the following description, this information will be referred to as measurement period-position correspondence information as necessary.

<Reflection echo processing unit 405>
The reflected echo processing unit 405 performs signal processing on the reflected echo signal that has been subjected to reception processing by the reflected echo acquisition unit 403. As a result, a cross-sectional echo waveform in each measurement period is obtained for each of the reflected echoes received by the ultrasound probes 110a to 110d. The cross-sectional echo waveform indicates the relationship between the intensity of the reflected echo (ultrasonic wave) and the distance from the ultrasound incident plane along the propagation direction of the ultrasound wave.

FIG. 5 is a diagram conceptually showing an example of a cross-sectional echo waveform group 510.
As described above, in this embodiment, the ultrasonic probes 110a to 110d perform vertical flaw detection, +angle flaw detection, and -angle flaw detection in order as a process in one cycle, and perform the process as a predetermined measurement. Repeat in cycles. Further, the ultrasonic probes 110a to 110d have a plurality of ultrasonic transducers and perform ultrasonic flaw detection using a volume focus phased array method. Therefore, in the same measurement period t, a number of cross-sectional echo waveforms corresponding to the number of ultrasonic transducers are obtained for each of vertical flaw detection, +angle flaw detection, and -angle flaw detection.

In FIG. 5, for example, in the measurement period t1, the numbers of the cross-sectional echo waveform group 511 by vertical flaw detection, the cross-sectional echo waveform group 512 by +angle flaw detection, and the cross-sectional echo waveform group 513 by -angle flaw detection are vertical. The number corresponds to the number of ultrasonic transducers used in flaw detection, +angle flaw detection, and -angle flaw detection. Such cross-sectional echo waveform groups 511, 512, and 513 are obtained in each measurement period t1 to tN. Furthermore, cross-sectional echo waveform groups 511, 512, and 513 at each measurement period t1 to tN are obtained for each of the ultrasound probes 110a to 110d. Here, the measurement periods t1 and tN are the measurement period when the square steel M starts facing the ultrasonic probes 110a to 110d, and the measurement period immediately before the square steel M stops facing the ultrasonic probes 110a to 110d, respectively. Therefore, the measurement periods t1 to tN differ depending on the ultrasound probes 110a to 110d.

In the example shown in FIG. 5, a surface echo 511a and a bottom echo 511b are shown in the cross-sectional echo waveform obtained by vertical flaw detection, but these are in areas different from the flaw detection ranges 311, 321, 331, and 341. It's an echo. Therefore, the reflected echo acquisition unit 403 does not extract the surface echo 511a and the bottom echo 511b, but only the defect echo 511c within the flaw detection ranges 311, 321, 331, and 341. In this way, echoes in areas different from the flaw detection ranges 311, 321, 331, and 341 are not extracted. Similarly, the reflected echo acquisition unit 403 does not extract the surface echo 512b included in the echo waveform obtained by the + oblique angle flaw detection, but only the defect echo 512b within the flaw detection ranges 312 and 322. In addition, the reflected echo acquisition unit 403 does not extract the surface echo 513b included in the cross-sectional echo waveform obtained by -angle flaw detection. Incidentally, FIG. 5 shows an example in which no defect echo is detected in -oblique angle flaw detection.

Next, the reflected echo processing unit 405 extracts the defect echoes within the flaw detection ranges 311, 321, 331, and 341 from the cross-sectional echo waveform group 511 obtained by vertical flaw detection obtained in the same measurement period t, and extracts the intensity (waveform Extracting the intensity of the defect echo with the maximum peak height is performed for each cross-sectional echo waveform group 511 in measurement periods t1 to tN. In the following description, the intensity of the defect echo extracted in this way will be referred to as the maximum echo intensity by vertical flaw detection, as necessary.

Similarly, the reflected echo processing unit 405 extracts defect echoes within the flaw detection ranges 312 and 322 from the cross-sectional echo waveform group 512 obtained in the same measurement cycle t and obtained by oblique flaw detection, and determines the intensity (the peak of the waveform). Extracting the intensity of the defect echo with the maximum height) is performed for each cross-sectional echo waveform group 512 in the measurement period t1 to tN. In the following description, the intensity of the defect echo extracted in this manner will be referred to as the maximum echo intensity obtained by + oblique angle flaw detection, if necessary.
In addition, the reflected echo processing unit 405 extracts defect echoes within the flaw detection ranges 313 and 343 from the group of cross-sectional echo waveforms 512 obtained in the same measurement period t by -angle flaw detection, and determines the intensity (the height of the peak of the waveform). Extracting the intensity of the defect echo with the maximum value (d) is performed for each cross-sectional echo waveform group 513 in the measurement period t1 to tN. In the following description, the intensity of the defect echo extracted in this way will be referred to as the maximum echo intensity by -angle flaw detection, if necessary.

As described above, the reflected echo processing unit 405 uses the ultrasonic probes 110a to 110d to derive the maximum echo intensity by vertical flaw detection, the maximum echo intensity by +angle flaw detection, and the maximum echo intensity by -angle flaw detection. This is done for each reflected echo obtained in . In the following description, the maximum echo intensity due to vertical flaw detection, the maximum echo intensity due to +angle flaw detection, and the maximum echo intensity due to -angle flaw detection are collectively referred to as maximum echo intensity as necessary. Here, we will explain the case where the intensity of the defect echo with the maximum intensity (waveform peak height) is extracted as the defect echo within the flaw detection range. A representative value other than the maximum value (for example, a median value or an average value) may be used.

Next, the reflected echo processing section 405 determines which position in the longitudinal direction (Y-axis direction) of the square steel M is located in each measurement period t1 to tN based on the measurement period-position correspondence information derived by the position derivation section 404. , and whether it is facing the ultrasonic probes 110a to 110d. According to the result of this determination, the reflected echo processing unit 405 derives the position in the longitudinal direction (Y-axis direction) of the square steel M corresponding to the measurement periods t1 to tN for each of the ultrasonic probes 110a to 110d.

Then, the reflected echo processing unit 405 converts the value of the maximum echo intensity obtained by the vertical flaw detection in each measurement period t1 to tN into the value of the position in the longitudinal direction (Y-axis direction) of the square steel M corresponding to each measurement period t1 to tN. The above steps are performed for each of the ultrasonic probes 110a to 110d. By doing so, the relationship between the maximum echo intensity by vertical flaw detection and the position in the longitudinal direction of the square steel M can be obtained for each of the ultrasonic probes 110a to 110d.

Similarly, the reflected echo processing unit 405 calculates the value of the maximum echo intensity by +angle flaw detection for each measurement period t1 to tN at the position in the longitudinal direction (Y-axis direction) of the square steel M corresponding to each measurement period t1 to tN. This is done for each of the ultrasonic probes 110a to 110d. By doing this, the relationship between the maximum echo intensity obtained by +angle flaw detection and the position in the longitudinal direction of the square steel M can be obtained for each of the ultrasonic probes 110a to 110d.
In addition, the reflected echo processing unit 405 calculates the value of the maximum echo intensity by -angle flaw detection for each measurement period t1 to tN at the position in the longitudinal direction (Y-axis direction) of the square steel M corresponding to each measurement period t1 to tN. This process is performed for each of the ultrasonic probes 110a to 110d. By doing this, the relationship between the maximum echo intensity by oblique flaw detection and the longitudinal position of the square steel M can be obtained for each of the ultrasonic probes 110a to 110d.

FIG. 6 is a diagram conceptually showing an example of the relationship between the maximum echo intensity and the position of the square steel M in the longitudinal direction (Y-axis direction). As mentioned above, herein, the maximum echo intensity due to vertical flaw detection, the maximum echo intensity due to +angle flaw detection, and the maximum echo intensity due to -angle flaw detection are collectively referred to as the maximum echo intensity.
The plots (●) shown in FIGS. 6(a) and 6(b) are the maximum echo intensity. For example, by performing interpolation processing or curve fitting using the maximum echo intensity, a curve showing the relationship between the maximum echo intensity and the position of the square steel M in the longitudinal direction is obtained.
As described above, a curve showing the relationship between the maximum echo intensity by vertical flaw detection and the longitudinal position of the square steel M, + a curve showing the relationship between the maximum echo intensity by oblique flaw detection and the longitudinal position of the square steel M, and - A curve showing the relationship between the maximum echo intensity by oblique flaw detection and the longitudinal position of the square steel M is obtained for each of the ultrasonic probes 110a to 110d.

<Storage unit 406>
The storage unit 406 stores curves derived for each of the ultrasonic probes 110a to 110d by the reflected echo processing unit 405 that indicate the relationship between the maximum echo intensity by vertical flaw detection and the position in the longitudinal direction of the square steel M, and the curves derived by +oblique flaw detection for each of the ultrasonic probes 110a to 110d. Information indicating a curve showing the relationship between the maximum echo intensity and the longitudinal position of the square steel M, and a curve showing the relationship between the maximum echo intensity by angle angle flaw detection and the longitudinal position of the square steel M is stored. In the following description, when at least some of the information stored in the storage unit 406 is collectively referred to as an echo intensity-position relationship, as necessary.

<Defect determination unit 407>
The defect determination unit 407 determines whether there is a defect inside the square steel M based on the echo intensity-position relationship stored in the storage unit 406.
As described above, in this embodiment, the presence or absence of defects is detected in the detection ranges 311, 321, 331, and 341 (or their surroundings) when vertical flaw detection is performed. At each position in the longitudinal direction of the square steel M, if there is a defect in at least two of the following three flaw detection ranges, the defect determination unit 407 determines that there is a defect at that position. The first of the three flaw detection ranges is flaw detection ranges 311, 321, 331, and 341 when performing vertical flaw detection. The second of the three flaw detection ranges is a flaw detection range that partially overlaps with the flaw detection ranges 311, 321, 331, and 341 among the flaw detection ranges when + oblique flaw detection is performed. The third of the three flaw detection ranges is a flaw detection range that partially overlaps with the flaw detection ranges 311, 321, 331, and 341 among the flaw detection ranges when performing -angle flaw detection.

To explain more specifically an example of the criteria for determining the presence or absence of a defect, the defect determination unit 407 determines whether at least one of the following first to fourth conditions is satisfied at each position in the longitudinal direction of the square steel M. If so, it is determined that there is a defect at that position.
The first condition is a flaw detection range 311 when performing vertical flaw detection with the ultrasonic probe 110a, a flaw detection range 322 when performing +angle flaw detection with the ultrasonic probe 110b, and a flaw detection range 322 when performing -angle flaw detection with the ultrasonic probe 110d. The condition is that there is a defect in at least two of the flaw detection ranges 343 when performing flaw detection.

The second condition is a flaw detection range 321 when performing vertical flaw detection with the ultrasonic probe 110b, a flaw detection range when performing +angle flaw detection with the ultrasonic probe 110c, and a flaw detection range 321 when performing -angle flaw detection with the ultrasonic probe 110a. The condition is that there is a defect in at least two of the flaw detection ranges 313 in the case.

The third condition is a flaw detection range 331 when performing vertical flaw detection with the ultrasonic probe 110c, a flaw detection range when performing +angle flaw detection with the ultrasonic probe 110d, and a flaw detection range 331 when performing -angle flaw detection with the ultrasonic probe 110b. The condition is that there is a defect in at least two of the flaw detection ranges in the case.

The fourth condition is a flaw detection range 341 when performing vertical flaw detection with the ultrasonic probe 110d, a flaw detection range 312 when performing +angle flaw detection with the ultrasonic probe 110a, and a flaw detection range 312 when performing -angle flaw detection with the ultrasonic probe 110c. The condition is that there is a defect in at least two of the flaw detection ranges when performing flaw detection.
In the following explanation, for the first condition to the fourth condition, the three flaw detection ranges included in the same condition (vertical flaw detection, + oblique flaw detection, and - oblique flaw detection) will be explained as necessary. , is called a flaw detection range set. For example, the flaw detection range set for the first condition consists of flaw detection ranges 311, 322, and 343.

In this embodiment, the echo intensity-position relationship as shown in FIG. 6 is obtained for vertical flaw detection, + oblique angle flaw detection, and - oblique angle flaw detection using the ultrasonic probes 110a to 110d. That is, 12 (=4×3) echo intensity-position relationships as shown in FIG. 6 are obtained.
In such an echo intensity-position relationship, the defect determination unit 407 compares the maximum echo intensity with the threshold value at each position (each position on the horizontal axis) in the longitudinal direction (Y-axis direction) of the square steel M. , determine the presence or absence of a defect at the position.

In this embodiment, a first threshold value is set in advance for each echo intensity-position relationship. The defect determining unit 407 determines whether the maximum echo intensity exceeds the first threshold TH1 in the echo intensity-position relationship. For example, suppose that the echo intensity-positional relationship 601 shown in FIG. 6(a) is the echo intensity-positional relationship when vertical flaw detection is performed with the ultrasonic probe 110a. In this case, in the echo intensity-positional relationship 601, the range on the horizontal axis (positions in the longitudinal direction (Y-axis direction) of the square steel M) in which the maximum echo intensity (vertical axis) exceeds the first threshold TH1 is from the position YL to the position The range is up to YH.

Comparison with the first threshold value may be performed in this manner for all echo intensity-position relationships, but depending on the orientation of the defect, etc., each flaw detection method (vertical flaw detection, + oblique flaw detection, The ease with which defects can be detected (intensity of reflected echo) by flaw detection differs. Therefore, in the present embodiment, the defect determination unit 407 improves defect detection accuracy by changing the first threshold value to the second threshold value as described below. The second threshold is a value (a value smaller than the first threshold) that makes it easier to detect defects than the first threshold. Here, a value obtained by subtracting a predetermined value from the first threshold is set as the second threshold.

An example of the process of changing the first threshold value to the second threshold value will be described with reference to the example shown in FIG. 6. As shown in FIG. 6(a), when there is an echo intensity-positional relationship 601 that exceeds the first threshold TH1 in the echo intensity-positional relationship in the three flaw detection ranges included in the same flaw detection range set, the defect determination unit 407 derives a range YL to YH of positions in the longitudinal direction of the square steel M that exceed the first threshold TH1 in the echo intensity-position relationship 601. When the number of echo intensity-position relationships exceeding the first threshold TH1 is two, two ranges YL to YH of positions in the longitudinal direction of the square steel M exceeding the first threshold TH1 are obtained. In this case, the defect determination unit 407 selects the wider range of the two ranges YL to YH.

Next, the defect determination unit 407 expands the range YL to YH of the longitudinal position of the square steel M exceeding the first threshold TH1 by a predetermined value YA on the lower limit value side and the upper limit value side, respectively. (=YL-YA) to YH' (=YH+YA) are derived (see FIG. 6(b)).
Next, as shown in FIG. 6(b), the defect determination unit 407 determines whether the first The threshold in the range YL' to YH' of the echo intensity-position relationship 602 that does not exceed the threshold TH1 is changed from the first threshold TH1 to the second threshold TH2. Then, the defect determining unit 407 determines whether or not the maximum echo intensity exceeds the second threshold TH2 for the range YL' to YH' in the echo intensity-positional relationship 602.

As described above, the defect determining unit 407 determines whether the maximum echo intensity exceeds the threshold (first threshold TH1 or second threshold TH2) for all echo intensity-position relationships stored in the storage unit 406. The test is carried out at each position in the longitudinal direction of the square steel M.
Then, the defect determination unit 407 determines whether the maximum echo intensity exceeds a threshold value (first threshold value TH1 or second threshold value TH2) from the three echo intensities-positional relationships in the three flaw detection ranges included in the same flaw detection range set. The value of the horizontal axis (position in the longitudinal direction of the square steel M) is derived.

Then, the defect determination unit 407 determines that the maximum echo intensity at the same position in the longitudinal direction of the square steel M is a threshold value (first threshold value TH1) in two or more echo intensity-positional relationships among the three echo intensity-positional relationships. Alternatively, if it exceeds the second threshold value TH2), it is determined that there is a defect at the position. In this case, the defect determination unit 407 determines that there is a defect in the flaw detection range (or its surroundings) included in the flaw detection range set in which vertical flaw detection is performed.
On the other hand, the defect determination unit 407 determines that the maximum echo intensity exceeds the threshold (first threshold TH1 or second threshold TH2) in only one echo intensity-positional relationship among the three echo intensity-positional relationships. The maximum echo intensity does not exceed the threshold (first threshold TH1 or second threshold TH2) in the longitudinal position of the square steel M and in any of the three echo intensity-positional relationships. Regarding the position of the square steel M in the longitudinal direction, it is determined that no defects are found from the three echo intensity-position relationships.

For example, in the first condition described above, the flaw detection range set includes a flaw detection range 311 when performing vertical flaw detection with the ultrasonic probe 110a, a flaw detection range 322 when performing oblique flaw detection with the ultrasonic probe 110b, and This is a flaw detection range 343 when performing oblique flaw detection with the sonic probe 110d. The echo intensity-positional relationship 601 shown in FIG. 6(a) is the echo intensity-positional relationship when vertical flaw detection is performed with the ultrasonic probe 110a, and the echo intensity-positional relationship 602 shown in FIG. 6(b) is It is assumed that the echo intensity-position relationship is when + oblique flaw detection is performed using the ultrasonic probe 110b. In this case, in the two echo intensity-positional relationships 601 and 602, the maximum echo intensity exceeds the threshold (first threshold TH1 or second threshold TH2) in the longitudinal position range YL to YH of the square steel M. Therefore, the defect determining unit 407 determines that there is a defect in the flaw detection range 311 (or its surroundings) when performing vertical flaw detection with the ultrasonic probe 110a in the range YL to YH of the longitudinal position of the square steel M. On the other hand, the defect determination unit 407 determines that no defects are found at other positions in the longitudinal direction of the square steel M under the first condition.

In addition, in the echo intensity-positional relationships 601 and 602 shown in FIGS. 6(a) and 6(b), it is determined that no defects are found in a range other than the longitudinal position range YL to YH of the square steel M. . However, in other echo intensity-position relationships, the maximum echo intensity may exceed the threshold (first threshold TH1 or second threshold TH2) in a range other than the longitudinal position range YL to YH of the square steel M. be. That is, even if it is determined that no defect is found in a position in the longitudinal direction of the square steel M under the first condition, it may be determined that there is a defect at that position under the second to fourth conditions. obtain. If the defect determining unit 407 determines that no defect is found under all of the first to fourth conditions at the same position in the longitudinal direction of the square steel M, it determines that there is no defect at that position.
Note that the first threshold TH1 and the second threshold TH2 may be the same for all echo intensity-position relationships, or may be different for at least some echo intensity-position relationships.

Here, the reason why it is preferable to perform water column type (local water immersion type) ultrasonic flaw detection will be explained. As described above, in the present embodiment, the defect determining unit 407 determines that there is a defect at each position in the longitudinal direction of the square steel M if at least one of the first to fourth conditions is satisfied. judge. For example, in order to determine whether the first condition is satisfied, the results of vertical flaw detection with the ultrasonic probe 110a, the results of +angle flaw detection with the ultrasonic probe 110b, and the results of -angle flaw detection with the ultrasonic probe 110d are used. The results of corner flaw detection are used. Therefore, in ultrasonic flaw detection to determine whether the first condition is satisfied, ultrasonic waves propagate through water disposed between the ultrasonic probes 110a, 110b, 110d and the square steel M. do. Similarly, in ultrasonic flaw detection to determine whether the second condition is satisfied, ultrasonic waves are transmitted through water placed between the ultrasonic probes 110b, 110c, 110a and the square steel M. propagate. In addition, in ultrasonic flaw detection for determining whether the third condition is satisfied, ultrasonic waves propagate through water disposed between the ultrasonic probes 110c, 110d, 110b and the square steel M. do. In addition, in ultrasonic flaw detection for determining whether the fourth condition is satisfied, ultrasonic waves propagate through water disposed between the ultrasonic probes 110d, 110a, 110c and the square steel M. do.

Therefore, for example, if the ultrasonic probes 110a to 110d and the square steel M are arranged in the same water tank, the water placed in the area between the ultrasonic transmission surface of the ultrasonic probes 110a to 110d and the square steel M is If they are not separated (that is, if water immersion type ultrasonic flaw detection is used), there is a possibility that bubbles will occur between the ultrasonic probes 110a to 110d and the square steel M at the same time. . This is because the distribution of bubble generation positions is isotropic, and the generated bubbles move. On the other hand, if the water placed in the area between the ultrasonic transmitting surface of the ultrasonic probes 110a to 110d and the square steel M is prevented from communicating with each other (that is, the ultrasonic wave of the local water immersion type (water column type) If flaw detection is used), even if bubbles occur in one area, the possibility that bubbles will occur in other areas at the same time is lower than with the water immersion method. Therefore, it is possible to suppress a decrease in defect detection accuracy.

<Output section 408>
The output unit 408 outputs information indicating the result of the defect search by the defect determination unit 407. As a form of output, for example, at least one of displaying on a computer display, transmitting to an external device, and storing in a storage medium inside or outside the defect detection device 400 can be adopted. The information indicating the defect search result by the defect determination unit 407 can include, for example, the position in the longitudinal direction of the square steel M where it has been determined that there is a defect. Further, the information indicating the defect search results by the defect determination unit 407 includes, for example, the cross-sectional area of the square steel M (flaw detection ranges 311, 321, 331, 341 (or the surrounding area)) where it has been determined that there is a defect. be able to. If there is no defect, information indicating this fact becomes information indicating the defect search result.

Next, an example of a process in which the defect detection device 400 derives and stores the echo intensity-position relationship will be described with reference to the flowchart in FIG.
First, in step S<b>701 , the flaw-detected material detection unit 401 waits until the beginning of the square steel M is detected by the sensor 210 based on a signal output from the sensor 210 . Then, when the leading edge of the square steel M is detected by the sensor 210, the process advances to step S702. Steps S702 to S709 are repeatedly performed at a predetermined measurement cycle. Further, in this case, it is assumed that the ultrasonic flaw detection is performed in the order of vertical flaw detection, + oblique angle flaw detection, and - oblique angle flaw detection. Therefore, the processes of steps S702 to S704 are repeated three times in the same measurement cycle.

When the process proceeds to step S702, the ultrasound output instruction unit 402 performs a transmission process and outputs a control signal for controlling the ultrasound transmission operation to the ultrasound probes 110a to 110d. In the first step S702 in the same measurement cycle, the ultrasonic output instruction unit 402 sends a control signal to control the transmission operation for performing vertical flaw detection on the ultrasonic probes 110a to 110d as an ultrasonic transmission operation. Output. In the second process of step S702 in the same measurement cycle, the ultrasonic output instruction unit 402 controls a transmission operation for performing +angle flaw detection on the ultrasonic probes 110a to 110d as an ultrasonic transmission operation. Outputs a control signal. In the third step S702 in the same measurement cycle, the ultrasonic output instruction unit 402 controls a transmission operation for performing -angle flaw detection on the ultrasonic probes 110a to 110d as an ultrasonic transmission operation. Outputs a control signal.

Further, the defect detection device 400 performs the following process in step S702 at the first timing when the square steel M reaches a position where the tips of the holders 120a to 120d can be contacted. That is, the defect detection device 400 moves the holders 120a to 120d together with the ultrasonic probes 110a to 110d so that the tips of the holders 120a to 120d come into contact with the square steel M, prior to the above-described ultrasonic transmission operation, A control signal instructing the supply of water into the hollow regions of the holders 120a-120d is sent to a control device that controls the position of the holders 120a-120d and the supply of water.
Note that the ultrasonic output instruction unit 402 transmits the ultrasonic waves as described above for an ultrasonic probe corresponding to a holder among the holders 120a to 120d in which the square steel M has not reached a position where the tip of the holder can be contacted. Does not output control signals that control operations.

Next, in step S703, the reflected echo acquisition unit 403 inputs reflected echo signals received by the ultrasound probes 110a to 110d when the ultrasound probes 110a to 110d transmit ultrasound, and performs reception processing. In the first step S703 in the same measurement cycle, the reflected echo acquisition unit 403 inputs a reflected echo signal obtained by vertical flaw detection. In the process of step S703 for the second time in the same measurement period, the reflected echo acquisition unit 403 inputs the signal of the reflected echo obtained by + oblique angle flaw detection. In the third step S703 in the same measurement cycle, the reflected echo acquisition unit 403 inputs the signal of the reflected echo obtained by -angle flaw detection.

Next, in step S704, the defect detection apparatus 400 determines whether vertical flaw detection, +angle flaw detection, and -angle flaw detection have been performed in the current measurement cycle. As a result of this determination, if vertical flaw detection, +angle angle flaw detection, and -angle angle flaw detection are not performed in the current measurement cycle, the process returns to step S702. Then, the processes of steps S702 to S704 are repeatedly derived until vertical flaw detection, +angle angle flaw detection, and -angle angle flaw detection are performed in the current measurement cycle. Then, in the current measurement cycle, when vertical flaw detection, +angle angle flaw detection, and -angle angle flaw detection are performed, the process advances to step S705.

When the process proceeds to step S705, the position derivation unit 404 obtains information indicating which position in the longitudinal direction (Y-axis direction) of the square steel M faces the ultrasonic probes 110a to 110d in the current measurement cycle. (Measurement cycle-position correspondence information in the current measurement cycle) is derived.
Next, in step S706, the reflected echo processing unit 405 performs signal processing on the reflected echo signal subjected to reception processing in step S703, and derives a group of cross-sectional echo waveforms in the current measurement cycle. The cross-sectional echo waveform indicates the relationship between the intensity of the reflected echo (ultrasonic wave) and the distance from the ultrasound incident plane along the propagation direction of the ultrasound wave. As shown in FIG. 5, in the same measurement period t, a cross-sectional echo waveform group 511 by vertical flaw detection, a cross-sectional echo waveform group 512 by +angle flaw detection, and a cross-sectional echo waveform group 513 by -angle flaw detection exceed Obtained for each of the sonic probes 110a to 110d.

Next, in step S707, the reflected echo processing unit 405 derives the maximum echo intensity in the current measurement cycle. Specifically, the reflected echo processing unit 405 derives the maximum echo intensity by vertical flaw detection in the current measurement cycle from the cross-sectional echo waveform group by vertical flaw detection in the current measurement cycle, and derives the maximum echo intensity by vertical flaw detection in the current measurement cycle. From the group of cross-sectional echo waveforms in the current measurement cycle, derive the maximum echo intensity by +angle flaw detection in the current measurement cycle, and from the group of cross-sectional echo waveforms in the -angle flaw detection in the current measurement cycle, calculate the -angle intensity in the current measurement cycle. Deriving the maximum echo intensity by flaw detection.

Next, in step S708, the reflected echo processing unit 405 calculates the maximum echo intensity in the current measurement cycle derived in step S708 based on the measurement cycle-position correspondence information in the current measurement cycle derived in step S705. , to the maximum echo intensity at the position in the longitudinal direction (Y-axis direction) of the square steel M, and derive the maximum echo intensity at the position in the longitudinal direction (Y-axis direction) of the square steel M corresponding to the current measurement cycle. For example, the reflected echo processing unit 405 determines at what position in the longitudinal direction of the square steel M the maximum echo intensity by vertical flaw detection in the current measurement cycle derived in step S708 is, and at the current value derived in step S708. At what position in the longitudinal direction of the square steel M is the maximum echo intensity due to + oblique flaw detection in the measurement cycle of ? and the maximum echo intensity due to - oblique flaw detection in the current measurement cycle derived in step S708. It is determined at what position in the longitudinal direction of the square steel M the value is.

Next, in step S709, the defect detection device 400 determines whether the inspection of the square steel M has been completed. For example, the defect detection device 400 is based on the time when the tail end of the square steel M is detected by the sensor 210, the conveyance speed of the square steel M, and the distance from the sensor 210 to the ultrasonic probe 110d in the conveyance direction of the square steel M. , it is determined whether the square steel M is located downstream of the ultrasonic probe 110d. Then, the defect detection device 400 determines that the inspection of the square steel M is completed at the first timing when the square steel M is located downstream of the ultrasonic probe 110d. As a result of this determination, if the inspection of the square steel M has not been completed, the process returns to step S702, and the processes of steps S702 to S709 in the next measurement cycle are executed. The processes of steps S702 to S709 are repeatedly executed at a predetermined measurement cycle until the inspection of the square steel M is completed.

If it is determined that the inspection of the square steel M has been completed, the process proceeds to step S710. When the process proceeds to step S710, the reflected echo processing unit 405 calculates the echo intensity - based on the value of the maximum echo intensity at the position in the longitudinal direction (Y-axis direction) of the square steel M derived in step S708 in each measurement period. A positional relationship is derived (see echo intensity-positional relationships 601 and 602 in FIG. 6). For example, the reflected echo processing unit 405 derives the echo intensity-position relationship when vertical flaw detection is performed, based on the maximum echo intensity by vertical flaw detection at each position in the longitudinal direction (Y-axis direction) of the square steel M. Similarly, the reflected echo processing unit 405 calculates the echo intensity-positional relationship when + oblique flaw detection is performed, based on the maximum echo intensity by + oblique flaw detection at each position in the longitudinal direction (Y-axis direction) of the square steel M. Derive. Further, the reflected echo processing unit 405 calculates the echo intensity-positional relationship when performing oblique flaw detection based on the maximum echo intensity by oblique flaw detection at each position in the longitudinal direction (Y-axis direction) of the square steel M. Derive. In this embodiment, the four ultrasonic probes 110a to 110d perform vertical flaw detection, +angle flaw detection, and -angle flaw detection, so 12 echo intensity-position relationships are derived.

Next, in step S711, the reflected echo processing unit 405 causes the storage unit 406 to store the echo intensity-position relationship derived in step S710. Then, the process according to the flowchart of FIG. 7 ends.

Next, an example of a process in which the defect detection device 400 determines and outputs the presence or absence of a defect in the square steel M will be described with reference to the flowchart in FIG. The flowchart in FIG. 8 is executed after the process according to the flowchart in FIG. 7 is completed.
First, in step S801, the defect determination unit 407 selects one flaw detection range set. The flaw detection range set is three flaw detection ranges included in each of the first to fourth conditions (vertical flaw detection, +angle flaw detection, and -flaw detection range by -angle flaw detection). The process of step S801 is a process of selecting the first to fourth conditions. The processes in steps S802 to S806 are processes for determining whether or not the condition corresponding to the flaw detection range set selected in step S801 is satisfied among the first to fourth conditions. Therefore, the processing of steps S801 to S806 is repeated four times.

Next, in step S802, the defect determination unit 407 selects the flaw detection range included in the flaw detection range set selected in step S801 among the 12 echo intensity-position relationships stored in step S711 of the flowchart in FIG. Read out the echo intensity-position relationship. For example, the first condition is a flaw detection range 311 when performing vertical flaw detection with the ultrasonic probe 110a, a flaw detection range 322 when performing +angle flaw detection with the ultrasonic probe 110b, and a -angle flaw detection using the ultrasonic probe 110d. The condition is that there is a defect in at least two of the flaw detection ranges 343 when flaw detection is performed. Therefore, the defect determination unit 407 determines the echo intensity-positional relationship when performing vertical flaw detection with the ultrasonic probe 110a, the echo intensity-positional relationship when performing oblique flaw detection with the ultrasonic probe 110b, and the ultrasonic Using the probe 110d, three echo intensity-positional relationships are read out: the echo intensity-positional relationship when oblique flaw detection is performed.

Next, in step S803, the defect determination unit 407 determines which of the three echo intensity-positional relationships read out in step S802, the echo intensity for which the threshold value needs to be changed from the first threshold value TH1 to the second threshold value TH2. Determine whether there is a positional relationship. For example, the defect determination unit 407 determines that among the three echo intensity-positional relationships read in step S802, there is an echo intensity-positional relationship that exceeds the first threshold TH1, and an echo intensity-positional relationship that exceeds the first threshold TH1. If there is an echo intensity-position relationship that does not exceed the threshold TH1 of 1, it is determined that there is an echo intensity-position relationship that requires changing the threshold, and if not, the echo that requires changing the threshold. It is determined that there is no strength-position relationship. As a result of this determination, if there is no echo intensity-position relationship that requires changing the threshold, the process skips step S804 and proceeds to step S805, which will be described later.

On the other hand, if there is an echo intensity-position relationship that requires changing the threshold, the process proceeds to step S804. When the process proceeds to step S804, the defect determination unit 407 determines whether the The threshold for the echo intensity-position relationship that does not exceed the first threshold TH1 is changed to the second threshold TH2. For example, as shown in FIG. 6, in the echo intensity-positional relationship 601 that exceeds the first threshold TH1, the defect determination unit 407 detects the range YL to YH of the longitudinal position of the square steel M that exceeds the first threshold TH1. Then, a range YL' (=YL-YA) to YH' (=YH+YA) is derived by widening the range YL to YH by a predetermined value YA for each of the lower limit value side and the upper limit value side. Then, the defect determination unit 407 sets a threshold value in the range YL' to YH' of the echo intensity-positional relationship 602 that does not exceed the first threshold value TH1 at any position in the longitudinal direction of the square steel M, from the first threshold value TH1 to the first threshold value TH1. The threshold value TH2 is changed to 2.

Next, in step S805, the defect determination unit 407 determines whether the defect is defective based on the result of comparing the three echo intensity-position relationships read out in step S802 with a threshold (first threshold TH1 or second threshold TH2). Determine the presence or absence of. If there is a defect, the defect determining unit 407 identifies the position in the longitudinal direction of the square steel M where the defect exists and the cross-sectional area of the square steel M where the defect exists.
For example, the defect determination unit 407 determines that in the three echo intensity-position relationships read in step S802, the value of the maximum echo intensity exceeds the threshold (first threshold TH1 or second threshold TH2) in the longitudinal direction of the square steel M. Derive the position of. Then, the defect determination unit 407 determines that the maximum echo intensity at the same position in the longitudinal direction of the square steel M is a threshold value (first threshold value TH1) in two or more echo intensity-positional relationships among the three echo intensity-positional relationships. If it exceeds the second threshold TH2), it is determined that there is a defect at that position, and if not, it is determined that no defect is found from the three echo intensity-position relationships. In addition, the defect determining unit 407 determines that the cross-sectional area of the square steel M in which the defect exists is the flaw detection range (or its surroundings) when vertical flaw detection is performed, which is included in the flaw detection range set selected in step S801. . The defect determination unit 407 performs such determination at all positions in the longitudinal direction of the square steel M.

Next, in step S806, the defect detection apparatus 400 determines whether the four flaw detection range sets corresponding to the first to fourth conditions have been selected in step S801. As a result of this determination, if the four flaw detection range sets corresponding to the first to fourth conditions are not selected in step S801, the process returns to step S801. Then, the processes of steps S801 to S806 are repeatedly executed until the processes of steps S801 to S805 are performed for the four flaw detection range sets. Thereby, whether or not the first to fourth conditions are satisfied is determined at all positions in the longitudinal direction of the square steel M.

Then, when four flaw detection range sets corresponding to the first to fourth conditions are selected in step S801, the process advances to step S807. When the process advances to step S807, the output unit 408 outputs information indicating the defect search result in step S805. The output unit 408 can output, as information indicating the defect search result, information including, for example, the longitudinal position of the square steel M where the defect exists and the cross-sectional area of the square steel M where the defect exists. Further, if there is no defect, the output unit 408 outputs information indicating this as information indicating the defect search result. Then, the process according to the flowchart of FIG. 8 ends.

9 and 10 are diagrams showing specific examples of the echo intensity-position relationship. Here, the echo intensity-position relationship for a square steel M having a longitudinal length of 10,600 (mm) is shown. 9 and 10, the horizontal axis indicates the position of the square steel M in the longitudinal direction (Y-axis direction). Here, the value on the horizontal axis is expressed with the position of the tail end of the square steel M as 0 (mm). Moreover, in FIGS. 9 and 10, the vertical axis indicates the maximum echo intensity. The unit of the maximum echo intensity is, for example, dB, but here the maximum echo intensity is expressed as a relative value (the maximum echo intensity here is a dimensionless quantity).

9(a), FIG. 9(b), FIG. 9(c), and FIG. 9(d) show the echo intensity-position relationship when performing vertical flaw detection using the ultrasonic probes 110a, 110b, 110c, and 110d, respectively. It is. 10(a), FIG. 10(b), FIG. 10(c), and FIG. 10(d) show echo intensity vs. position when oblique flaw detection is performed using ultrasonic probes 110a, 110b, 110c, and 110d, respectively. It is a relationship. In FIG. 10, the echo intensity-positional relationship when + oblique angle flaw detection is performed and the echo intensity-positional relationship when - oblique angle flaw detection is performed are shown in combination. For example, FIG. 10(a) shows the echo intensity-positional relationship when +-angle flaw detection is performed by the ultrasonic probe 110a, and the echo intensity-positional relationship when -angle-angle flaw detection is performed by the ultrasonic probe 110a. It is a composite of

As mentioned above, the first condition is the flaw detection range 311 when performing vertical flaw detection with the ultrasonic probe 110a, the flaw detection range 322 when performing oblique flaw detection with the ultrasonic probe 110b, and the flaw detection range 322 when performing oblique flaw detection with the ultrasonic probe 110d. - The condition is that there is a defect in at least two of the flaw detection ranges 343 when performing oblique flaw detection. The echo intensity-position relationship corresponding to this condition is the echo intensity-position relationship shown in FIGS. 9(a), 10(b), and 10(d).

In FIGS. 9(a), 10(b), and 10(d), the horizontal axis (position in the longitudinal direction (Y-axis direction) of the square steel M) is in the range from around 4500 (mm) to around 5300 (mm). , the maximum echo intensity is large. As a result of actually checking the square steel M, there was a defect within the flaw detection range 311 when performing vertical flaw detection with the ultrasonic probe 110a within the range.

Therefore, in FIGS. 10(b) and 10(d), the maximum echo intensity increases in the range from around 4500 (mm) to around 5300 (mm) on the horizontal axis, respectively, when the ultrasound probe 110b It is presumed that this is due to the echo intensity-positional relationship when +angle-angle flaw detection is performed by the ultrasonic probe 110d, and the echo intensity-positional relationship when -angle-angle flaw detection is performed by the ultrasonic probe 110d. It is thought that the contribution of the echo intensity-positional relationship when -angle flaw detection is performed by the sonic probe 110b and the echo intensity-positional relationship when +angle flaw detection is performed by the ultrasonic probe 110d is small).

By determining whether or not two or more of these three echo intensity-positional relationships exceed the threshold, the ultrasound It is possible to suppress erroneous detection of noise caused by concave portions on the entrance surface of the ultrasonic wave or air bubbles in the water through which the ultrasonic waves propagate as defects. For example, in FIG. 9(a), even if the maximum echo intensity becomes large near 8500 (mm) on the horizontal axis (even if it exceeds the threshold), FIGS. 10(b) and 10(d) In the above, if the maximum echo intensity does not become large near 8500 (mm) on the horizontal axis (unless it exceeds the threshold), it is not determined that there is a defect near 8500 (mm) on the horizontal axis. Therefore, it is not necessary to set a large threshold value in order to prevent noise from being detected as a defect, so defects can be detected appropriately.

Moreover, the maximum echo intensity shown in FIG. 10(b) and FIG. 10(d) is smaller than the maximum echo intensity in FIG. 9(a). Therefore, for example, if the first threshold value TH1 for all echo intensity-position relationships is the same, there is a possibility that the maximum echo intensity does not exceed the threshold value in the echo intensity-position relationship in FIG. 9(a). On the other hand, the threshold value for the echo intensity-positional relationship in FIG. By changing the threshold value TH to TH, defects can be easily detected even with the echo intensity-position relationship shown in FIG. 9(a). In other words, even if the echo intensity is low depending on the orientation of the defect, the defect can be easily detected.

As described above, in the present embodiment, the defect detection apparatus 400 detects at least one of the flaw detection ranges of at least two of the vertical flaw detection, +angle flaw detection, and -angle flaw detection performed by mutually different ultrasonic probes. Set the flaw detection range so that some parts overlap with each other. The defect detection device 400 calculates an echo intensity-positional relationship when performing vertical flaw detection, an echo intensity-positional relationship when performing oblique flaw detection, and a flaw detection range that partially overlaps with the flaw detection range in the vertical flaw detection. The flaw detection range that partially overlaps with the flaw detection range in the vertical flaw detection, the echo intensity when the oblique flaw detection is performed, and the positional relationship are derived. If the maximum echo intensity exceeds the threshold value at the same position in the longitudinal direction of the square steel M in two or more of these three echo intensity-positional relationships, the defect detection device 400 detects the position. is determined to be defective. Therefore, noise based on the state of the ultrasonic incident surface or the state of the area between the ultrasonic probe and the ultrasonic incident surface transmitted from the ultrasonic probe is caused by defects existing inside the square steel M. It is possible to suppress false detections.

Furthermore, in this embodiment, since water column type ultrasonic flaw detection is performed, it is possible to suppress noise due to air bubbles from being included in each of the three echo intensity-position relationships described above. Therefore, defects existing inside the square steel M can be detected with higher accuracy.

Furthermore, in the present embodiment, the defect detection device 400 detects that among the three echo intensity-positional relationships described above, in the echo intensity-positional relationship in which the maximum echo intensity exceeds the first threshold, the maximum echo intensity is higher than the first threshold. Identify locations where the threshold is exceeded. Then, the defect detection device 400 detects a position including the specified position in the echo intensity-positional relationship in which the maximum echo intensity does not exceed the first threshold at any position among the three echo intensity-positional relationships described above. The threshold value of is changed from the first threshold value to a second threshold value that is smaller than the first threshold value. Therefore, it is possible to improve the accuracy of defect detection in the echo intensity-position relationship changed to the second threshold value. Therefore, defects existing inside the square steel M can be detected with higher accuracy.

Note that among the embodiments of the present invention described above, the functions possessed by the defect detection apparatus 400 can be realized by a computer executing a program. Furthermore, a computer-readable recording medium on which the program is recorded and a computer program product such as the program can also be applied as an embodiment of the present invention. As the recording medium, for example, a flexible disk, hard disk, optical disk, magneto-optical disk, CD-ROM, magnetic tape, nonvolatile memory card, ROM, etc. can be used.
Furthermore, the embodiments of the present invention described above are merely examples of implementation of the present invention, and the technical scope of the present invention should not be construed as limited by these. It is something. That is, the present invention can be implemented in various forms without departing from its technical idea or its main features.

110a to 110d: Ultrasonic probe, 120a to 120d: Holder, 311 to 313, 321 to 322, 331, 341, 343: Flaw detection range, 400: Defect detection device, 401: Tested material detection section, 402: Ultrasonic output Instruction unit, 403: Reflected echo acquisition unit, 404: Position derivation unit, 405: Reflected echo processing unit, 406: Storage unit, 407: Defect determination unit, 408: Output unit

Claims (11)

An ultrasonic flaw detection system that detects defects in a material to be flawed whose cross section perpendicular to the longitudinal direction is substantially rectangular by performing ultrasonic flaw detection using a phased array method,
four ultrasonic probes each having a plurality of ultrasonic transducers that can be placed along the surface of the material to be tested , one placed on each of the four sides of the substantially rectangular shape; one ultrasound probe ,
a defect detection means for detecting defects in the material to be tested based on reflected echoes received by the ultrasonic probe by transmitting ultrasonic waves from the ultrasonic probe to the material to be tested;
A flaw detection range when performing vertical flaw detection using the first ultrasonic probe that is the ultrasonic probe installed on one side of the four sides of the substantially rectangle, and one side of the four sides of the substantially rectangle. Using the second ultrasonic probe and the third ultrasonic probe, which are the ultrasonic probes installed on two sides located on both sides of the rectangle, one of the four sides of the substantially quadrilateral is opposite to the one side. At least a portion of the flaw detection range when performing oblique flaw detection for
The defect detection means transmits ultrasonic waves to the flaw detection range using the first ultrasonic probe, the second ultrasonic probe, and the third ultrasonic probe. If the intensity of at least two of the reflected echoes received by the apparatus exceeds a threshold value , it is determined that there is a defect in the material to be tested ; otherwise, it is determined that there is no defect in the material to be tested. An ultrasonic flaw detection system characterized by: The ultrasonic flaw detection according to claim 1 , wherein the vertical flaw detection is performed at the same position in the longitudinal direction of the material to be tested , with each of the four ultrasonic probes serving as the first ultrasonic probe . system. The ultrasonic flaw detection system according to claim 1 or 2, wherein the ultrasonic flaw detection system detects defects under the skin of the material to be flaw-detected. Water is placed in each of the regions between the ultrasonic wave transmission surfaces of the four ultrasonic probes and the ultrasonic wave incident surface of the material to be tested,
water disposed in a region between the ultrasonic wave transmitting surface of the ultrasonic probe and the ultrasonic wave incident surface of the tested material; and an ultrasonic transmitting surface of the ultrasonic probe that is different from the ultrasonic probe. The ultrasonic flaw detection system according to any one of claims 1 to 3 , characterized in that the ultrasonic flaw detection system does not communicate with water disposed in a region between the ultrasonic wave incident surface of the flaw-detected material and the ultrasonic wave incident surface of the flaw-detected material. . The ultrasonic flaw detection system according to any one of claims 1 to 4 , characterized in that ultrasonic flaw detection is performed using a volume focus phased array method. Claims 1 to 5 , wherein the defect detection means determines whether or not there is a defect in the material to be tested at each of a plurality of positions in the longitudinal direction of the material to be tested. The ultrasonic flaw detection system according to any one of the items above. The defect detection means derives a representative value of the intensity of the reflected echo received by the ultrasonic probe at each of a plurality of positions in the longitudinal direction of the material to be detected, and based on the derived result, determines the representative value of the intensity of the reflected echo received by the ultrasonic probe. reflected echo processing means for deriving, for each of the flaw detection ranges of the plurality of ultrasonic probes, an echo intensity-positional relationship indicating a relationship between a representative value of intensity based on the flaw detection target material and a longitudinal position of the flaw-detected material; and,
a defect determining means for determining the presence or absence of a defect in the material to be detected based on a result of comparing a representative value of the intensity of the reflected echo in the echo intensity-positional relationship with a threshold value for the echo intensity-positional relationship; It further has
The defect determination means detects the reflected echo at the same position in the echo intensity-positional relationship in the flaw detection ranges of the first ultrasonic probe, the second ultrasonic probe, and the third ultrasonic probe. 7. The ultrasonic flaw detection system according to claim 1 , wherein when the representative value of the intensity exceeds a threshold value, it is determined that there is a defect at the position. The defect determining means is configured to detect the defect at any position in the echo intensity-positional relationship with respect to the flaw detection ranges of the first ultrasonic probe, the second ultrasonic probe, and the third ultrasonic probe. The threshold value for the echo intensity-position relationship in which the representative value of the intensity of the reflected echo does not exceed the threshold value is defined as the flaw detection range of the first ultrasonic probe, the second ultrasonic probe, and the third ultrasonic probe. The echo intensity-positional relationship is changed based on the result of comparing the echo intensity-positional relationship in which a representative value of the intensity of the reflected echo exceeds the threshold value with the threshold value. 7. The ultrasonic flaw detection system described in 7 . The defect determining means is configured to detect the defect at any position in the echo intensity-positional relationship with respect to the flaw detection ranges of the first ultrasonic probe, the second ultrasonic probe, and the third ultrasonic probe. The first ultrasonic probe, the second ultrasonic probe, and the third Determining based on the range of positions in the echo intensity-positional relationship in which the representative value of the intensity of the reflected echo exceeds the threshold value in the echo intensity-positional relationship in the flaw detection range of the ultrasonic probe . The ultrasonic flaw detection system according to claim 7 or 8 , characterized by: The ultrasonic flaw detection system according to any one of claims 1 to 8 , wherein the material to be detected is square steel. four ultrasonic probes each having a plurality of ultrasonic transducers that can be placed along the surface of a material to be tested whose cross section perpendicular to the longitudinal direction is approximately square; An ultrasonic flaw detection method for detecting defects in the target material by performing ultrasonic flaw detection using a phased array method using four ultrasonic probes arranged one for each of the flaws, the method comprising :
a defect detection step of detecting defects in the material to be tested based on reflected echoes received by the ultrasonic probe by transmitting ultrasonic waves from the ultrasonic probe to the material to be tested;
A flaw detection range when performing vertical flaw detection using the first ultrasonic probe that is the ultrasonic probe installed on one side of the four sides of the substantially rectangle, and one side of the four sides of the substantially rectangle. Using the second ultrasonic probe and the third ultrasonic probe, which are the ultrasonic probes installed on two sides located on both sides of the rectangle, one of the four sides of the substantially quadrilateral is opposite to the one side. At least a portion of the flaw detection range when performing oblique flaw detection for
The defect detection step includes transmitting ultrasonic waves to the flaw detection range using the first ultrasonic probe, the second ultrasonic probe, and the third ultrasonic probe. If the intensity of at least two of the reflected echoes received by the apparatus exceeds a threshold value , it is determined that there is a defect in the material to be tested ; otherwise, it is determined that there is no defect in the material to be tested. An ultrasonic flaw detection method characterized by:

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