JP2617055B2 - Ultrasonic flaw detector for square billet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detector for a square billet which inspects for the presence or absence of a defect inside a square billet conveyed in a steel production line by using ultrasonic waves.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing a conventional ultrasonic flaw detector for square billets. In the figure, 1 is a square billet,
2a1, 2a2, 2a3, and 2a4 are vertical probes arranged on the surface A, and similarly, 2b1, 2b2 to 2d4 are vertical probes arranged on the surfaces B, C, and D, respectively.
a2 is an oblique probe arranged on the surface A, similarly 3b1, 3
b2 to 3d2 are bevel probes arranged on the plane B, C and D respectively, 4 is a transmitting / receiving circuit for transmitting to the vertical probe 2 and the bevel probe 3 and amplifying a received echo, A gate circuit 5 sets a gate for the flaw detection echo output from each transmission / reception circuit 4 and determines whether there is an echo equal to or higher than a preset defect determination level.
Reference numeral denotes a central directional defect processing circuit which receives a gate circuit output corresponding to the vertical probe 2 and determines whether or not a defect detected at the central portion of the angle billet 1 is a directional defect. FIG.
7A and 7B are diagrams illustrating a method of detecting a directional defect at the center of a corner billet, wherein 7a indicates a directional defect at the center, and 8 indicates a central region within the corner billet 1.

Next, the operation will be described. In FIG. 3, the vertical probes 2a1, 2a2, 2a3, 2
a4 emits an ultrasonic wave toward the surface A and the surface C facing thereto. The emitted ultrasonic waves travel straight toward the surface C, are reflected by the surface C, and return to the original vertical probes. If there is a defect on the way to the plane C, some ultrasonic waves are reflected by the defect and return to the original vertical probe. The ultrasonic waves returned to the vertical probes 2a1, 2a2, 2a3, 2a4 are converted into electric signals and sent to the transmission / reception circuits 4 corresponding to the respective probes. The electric signal sent to the transmission / reception circuit 4 is amplified and sent to the gate circuit 5 as a flaw detection echo. In the gate circuit 5, in order to detect a defect, an ultrasonic wave is emitted from the vertical probes 2a1, 2a2, 2a3, and 2a4, and the tailing of the surface echo by the surface A ends. One or a plurality of gates are set during a time period from the passage of the ultrasonic wave to immediately before the ultrasonic wave is reflected on the surface C, and the flaw detection echo height in the gate exceeds the preset defect determination level. It is determined whether there is a defect in the gate if it exceeds the threshold. This is because when the ultrasonic wave is reflected in the above-described square billet 1 and returns to the vertical probe, the larger the defect area parallel to the surface A, the larger the amount of reflected ultrasonic wave. Since the flaw detection echo at the part also becomes large, a defect echo determination level corresponding to the defect area to be detected is set based on the relationship between the size of the flaw detection echo and the defect area measured in advance. The reason why a plurality of gates are set is to identify the location of a defect by changing the gate position.

On the other hand, the ultrasonic waves emitted by the oblique probe 3a1 on the surface A travel obliquely in the direction of the surface D which is the side surface of the surface A, and the ultrasonic waves emitted between the surface D and the surfaces D and C It is reflected on the corner surface. If there is a defect on the way to the surface D or a corner surface between the surface D and the surface C, a part of the ultrasonic wave is reflected by the defect and returns to the original angle beam probe 3a1. The ultrasonic wave emitted from another angle beam probe 3a2 on the surface A travels obliquely in the direction of the surface B, which is the side surface of the surface A, and
And at the corner plane between planes B and C. Surface B
If there is a defect on the way to the corner surface between the surfaces B and C, a part of the ultrasonic wave is reflected by the defect and returns to the original angle beam probe 3a2. The ultrasonic waves returned to the oblique probes 3a1 and 3a2 are converted into electric signals, and the ultrasonic signals are returned to the vertical probes 2a.
As in the case of 1-2a4, after being sent to the transmission / reception circuit 4 corresponding to each oblique probe, the electric signal is amplified and sent to the gate circuit 5 as a flaw detection echo. In the gate circuit 5, in order to detect a defect, an ultrasonic wave is emitted from the oblique probes 3a1 and 3a2, the tailing of the surface echo by the surface A ends, and the ultrasonic wave passes between the surfaces A and C. One or a plurality of gates are set during a time period from immediately before the ultrasonic wave is reflected on the surface C or the corners at both ends of the surface C, and the flaw detection echo height in the gate is set in advance. It is checked whether the level exceeds the level. If the level is exceeded, it is determined that the gate has a defect.

[0005] The four vertical probes 2a1-2a4 on the surface A are determined by the probe arrangement and the gate setting on the surface A described above.
And the two beveled probes 3a1 and 3a2 remove all portions on the side of the plane C from the middle line between the planes A and C in the cross section of the square billet, except for a part of several mm along the plane C. To detect flaws.

Similarly to the plane A, the plane B has four vertical probes 2b1 to 2b4 and two oblique probes 3b1,
3b2, four vertical probes 2c1-2c4 and two oblique probes 3c1 and 3c2 on the surface C, and four vertical probes 2d1-2d4 and two The oblique probes 3d1 and 3d2 are arranged, and a flaw is detected by the same method as that for the surface A described above. According to the above method, the probes arranged on each surface detect the flaws on the surface side opposite to the surface on which the probe is arranged, and as a result, the cross-sectional direction of the square billet by all the probes Together the flaw locations, will testing the cross-section all of the square billet. The above is the general method in the ultrasonic testing device for a square billet using the vertical probe 2 and the oblique probe 3 to perform flaw detection from the surface of the square billet. If there is a defect, it can be detected as a defect.

Next, the directional defect processing will be described.
Directional defects occur during the manufacturing process of the square billet 1 and are thin,
These cracks have almost no thickness, and usually occur at the center of the square billet 1 for manufacturing reasons. Also,
Directional defects are often almost eliminated by rolling in the post-process after being inspected by the square billet ultrasonic flaw detector. Therefore, as a square billet ultrasonic flaw detector,
It is required to detect the directional defect separately from other defects such as inclusions.

FIG. 4 illustrates a directional defect processing in a conventional ultrasonic inspection apparatus for a square billet. S1 in the figure indicates a region where the area where the vertical probe 2a2 on the surface A is flaw-detected overlaps the area where the vertical probe 2b3 where the flaw is detected on the surface B overlaps. The area where a certain vertical probe 2a1 detects a flaw and the area where a vertical probe 2b3 on the surface B detects a flaw are overlapped. Now, as shown in FIG. 4, if there is a directional defect 7a extending over the two regions S1 and S2 and substantially parallel to the surface A, the directional defect 7a has a thin surface shape. The ultrasonic waves from the vertical probes 2a2 and 2a1 at A are reflected and return to the original vertical probes 2a2 and 2a1, but the ultrasonic waves from the vertical probe 2b3 at the surface B are thin. In addition, since the defect is substantially parallel to the direction of the ultrasonic wave, the amount of the ultrasonic wave reflected from the directional defect 7a and reaching the vertical probe 2b3 is small.

From the ultrasonic characteristics of the directional defect 7a, the vertical probes 2a2 and 2a1 on the surface A and the vertical probe 2b3 on the surface B, the central directional defect processing circuit 6
Then, the following judgment is made. In the central directional defect processing circuit 6, the output of the gate circuit 5 in the area S1 of the vertical probe 2a2 and the area S1 of the vertical probe 2b3 are obtained for the area S1.
When the output of the gate circuit 5 is compared, the vertical probe 2a2 is defective in the area S1, but if the vertical probe 2b3 has almost no reflected echo, the area S1 is defective.
The defect detected in 1 is determined to be a directional defect. Area S2
Also in the above, the defect detected from the output result of the gate circuit 5 in the region S2 of the vertical probes 2a1 and 2b3 is determined to be a directional defect. In this way the center directional defect processing circuit 6, the divided region in the central portion 8 of square billet 1, and flaw detection for each area, different 90-degree wound side <br/> direction probe It is determined from the output results of the gate circuits of the two vertical probes 2 whether the detected defect is a directional defect.

[0010]

Since the conventional ultrasonic flaw detector for square billets is constructed as described above, the directional defect protrudes not only at the center of the square billet but also outside the center. If there is such a large directional defect, the defect detected in the central area among the defects is determined as a directional defect, but in the area outside the central part, one direction is a vertical probe. In the other direction rotated by 90 degrees, the central directional defect processing circuit 6 uses the directional defect processing circuit 6 because the region is not a vertical probe but a flaw detector. There was a problem that a defect could not be determined. Note that the area outside the center, that is, the direction in which the flaw is detected by the vertical probe in one direction, is also used in the area that is flaw-detected by the oblique probe from the other direction rotated by 90 degrees. When the directional defect is extracted by the same logical judgment as that of the partial directional defect processing circuit 6, the flaw detection area beyond the center of the vertical probe is several mm from the surface facing the surface in contact with the vertical probe. The angle beam probe is one of the objectives of installing the angle beam probe, whereas the angle beam probe is a flaw detection area including the side surface. If a defect is detected only by the probe and not detected by the vertical probe, and this is set as a directional defect, even if there is a defect on the side surface, it is erroneously determined to be a directional defect. There is a contradiction that the original purpose of the angle beam probe, flaw detection, is impaired. It was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a large directional defect not only at the center of the square billet but also outside the center. For angle billets that can determine directional defects not only in the central area but also in the area outside the central part without impairing the original purpose of the angle beam probe, which is flaw detection on the side surface It is intended to obtain an ultrasonic flaw detector.

[0012]

SUMMARY OF THE INVENTION In the ultrasonic flaw detector for a square billet according to the present invention, a defect which is equal to or higher than a defect determination level is detected from the output of the gate circuit of the oblique probe, and the oblique angle detector detects the defect. If a defect cannot be detected from the gate circuit output of a vertical probe that is detecting flaws in the same location from the direction rotated 90 degrees in the cross section direction with the probe, the beveled probe detects a defect in the square billet cross section If the section in the center direction of the square billet adjacent to the place where the directional defect is the aforementioned directional defect from the result of the gate circuit output of the vertical probe, the defect detected by the oblique probe is also in the direction continuous from the center. It is provided with a subcutaneous directional defect processing circuit as a sexual defect.

[0013]

In the subcutaneous directional defect processing circuit according to the present invention, a defect equal to or higher than the defect determination level is detected from the gate circuit output of the oblique probe, and the oblique probe having detected the defect and the oblique probe in a cross-sectional direction have a 90-degree defect. If a defect cannot be detected from the gate circuit output of a vertical probe that is flaw-detecting the same location from the direction rotated by an angle, the corner adjacent to the location where the oblique probe has detected the defect in the cross section of the square billet If the section at the center of the billet is a directional defect based on the result of the gate circuit output of the vertical probe, the defect detected by the oblique probe is also a directional defect that is continuous from the center. If a defect is detected in the area outside the area, and if it is detected by both the angled probe and the vertical probe, the directional There was no defect, only the beveled probe was defective If there is a directional defect continuously extending from the center if the section at the center of the adjacent square billet is a directional defect, if there is no directional defect in the center section of the adjacent square billet, It is determined that the side surface is defective.

[0014]

【Example】

Embodiment 1 FIG. FIG. 1 is a configuration diagram of an ultrasonic flaw detector for a square billet showing an embodiment of the present invention. In the figure, 1 is a square billet, 2a1, 2a2, 2a3, 2a4 are vertical probes arranged on a plane A, and 2b1, 2b2 to 2d4 are vertical probes arranged on a plane B, a plane C, and a plane D, respectively. Tentacle, 3a
1, 3a2 are angled probes arranged on the surface A, and similarly, 3b
1, 3b2 to 3d2 denote angle probes arranged on plane B, plane C, and plane D, respectively, and 4 denote vertical probe 2 and angle probe 3
A transmitting and receiving circuit for transmitting to the receiver and amplifying the received echo,
Reference numeral 5 denotes a gate circuit that sets a gate for the flaw detection echo output from each transmission / reception circuit 4 and determines whether there is an echo equal to or higher than a preset defect determination level, and 6 corresponds to the vertical probe 2. A central part directional defect processing circuit for taking in the gate circuit output and determining whether or not the defect detected at the central part of the angular billet 1 is a directional defect; 9
Captures the output of the gate circuit of the oblique probe 3 and the vertical probe 2 and determines whether a defect detected outside the center of the angular billet 1 is a directional defect continuously extending from the center. This is a subcutaneous directional defect processing circuit for determination. FIG.
FIG. 7B is a diagram showing a detection method in the case where the angular billet 1 has a directional defect extending from the center to the subcutaneous part outside the center, and 7b shows a directional defect extending from the center to the subcutaneous part. Reference numeral 8 denotes a central portion showing a region in which a flaw is detected by applying ultrasonic waves from two directions different from each other only by the vertical probe 2 within the cross section of the square billet 1.

Next, the operation of the ultrasonic flaw detector for square billets according to the present invention will be described. Installation method of the vertical probe 2 and the oblique probe 3 in contact with the angular billet 1, and the vertical probe 2 and the oblique probe 3, the transmission / reception circuit 4, the gate circuit 5, and the central directional defect processing circuit The operation of No. 6 is the same as that of the conventional square billet ultrasonic flaw detector. The operation for the directional defect 7a remaining in the center portion 8 as shown in FIG. 4 is the same as that of the conventional ultrasonic testing device for a square billet.
The difference between the conventional ultrasonic testing device for square billet and the ultrasonic testing device for square billet according to the present invention is that, as shown in FIG. 2, the directional defect 7b extends not only to the center but also to the subcutaneous portion. This is the operation in the case. The operation of the ultrasonic flaw detector for square billets according to the present invention with respect to the directional defect 7b extending not only to the central part but also to the subcutaneous part will be described.

In FIG. 2, S1 denotes a region where the vertical probe 2a2 on the surface A is detecting a flaw and a vertical probe 2a on the surface B.
The area where the flaw detection area b3 overlaps indicates the area where the flaw detection area of the vertical probe 2a1 located on the surface A and the flaw detection area of the vertical probe 2b3 located on the surface B are shown. Indicates an overlapping area. S3 indicates an area of the vertical probe 2b3 on the surface B where the flaw is detected, which is located farther from the center 8 when viewed from the surface B side.
3 and plane D are several mm apart. S4 indicates an area surrounded by a line extending from the area where the oblique probe 3a1 is flaw-detected to the plane D in which the width of the area where the vertical probe 2b3 is flaw-detected on the plane B is extended. And encompasses the area S3. The directional defect 7b exists substantially parallel to the plane A and extends over the region S1, the region S2, and the region S3.

Since the ultrasonic beam of the oblique probe 3a1 is almost perpendicular to the surface of the directional defect 7b, the oblique probe 3a1
The output of the gate circuit 5 corresponding to the area S4 of a1 is defective. Also, since the ultrasonic beam of the vertical probe 2b3 on the plane B travels substantially parallel to the directional defect 7b,
The output of the gate circuit 5 corresponding to the area S3 of the vertical probe 2b3 has no defect. Region S4 of the oblique probe 3a1
Is sent to the subcutaneous directional defect processing circuit 9 as defective, the subcutaneous directional defect processing circuit 9 removes the area S3 covering most of the area S4. Then, the output of the gate circuit 5 corresponding to the area S3 of the vertical probe 2b3 that is being inspected from the direction rotated by 90 degrees is confirmed. If the result is defective, area 3
In the above case, the output of the gate circuit 5 corresponding to the area S3 of the vertical probe 2b3 has no defect. The status of the area S2, which is the area in the unit 8, is confirmed. In the area S2, the vertical probe 2a1 on the surface A has a defect, and the vertical probe 2b3 on the surface B has no defect. The result is that there is a directional defect parallel to A.

The result of the region S4 detected from the surface A is defective, the result of the region S3 detected from the surface B rotated by 90 degrees from the surface A is no defect, and the result is a region in the central portion 8 adjacent to the region S4. If the result of the region S2 indicates that there is a directional defect parallel to the plane A, the defect detected in the region S4 is determined to be that the directional defect detected in the region S2 has extended to the subcutaneous part. If the result of the area S2 is no defect or a directional defect parallel to the A-plane, the defect detected in the area S4 is a part of the area S4 excluding the area S3. Alternatively, it is determined that the defect exists near the surface D.

The operation of the subcutaneous directional defect processing circuit 9 for the region S4, which is one of the subcutaneous parts, has been described above. Confirmation and judgment are sequentially performed for all areas.

[0020]

As described above, according to the present invention, a defect equal to or higher than the defect determination level is detected from the output of the gate circuit of the oblique probe, and the defect is detected in the sectional direction with the oblique probe that detected the defect. If a defect cannot be detected by the gate circuit output of the vertical probe that is detecting a flaw in the same place from the direction rotated by 90 degrees,
In the cross section of a square billet, if the section in the center direction of the square billet adjacent to the location where the beveled probe detects the defect is a directional defect from the result of the gate circuit output of the vertical probe, the bevelled probe By providing a subcutaneous directional defect processing circuit that also detects defects detected by the child as directional defects, directional defects extending continuously from the center of the square billet to the subcutaneous part are located in the subcutaneous part. Can also be detected as a directional defect.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an ultrasonic flaw detector for a square billet according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state in which a directional defect extending from a central portion to a subcutaneous portion continuously from the central portion of the ultrasonic testing device for a square billet according to one embodiment of the present invention is detected.

FIG. 3 is a diagram showing a configuration of a conventional ultrasonic inspection device for a square billet.

FIG. 4 is a diagram showing a state in which a directional defect located at the center of a conventional ultrasonic inspection device for a square billet is inspected.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Square billet 2 Vertical probe 3 Angle probe 4 Transmitter / receiver circuit 5 Gate circuit 6 Central directional defect processing circuit 7 Directional defect 9 Subcutaneous directional defect processing circuit

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yukio Mitani 325 Kamimachiya, Kamakura-shi Kamakura Works, Mitsubishi Electric Corporation (56) References JP-A-3-257362 (JP, A) JP-A-59-148860 (JP, A) JP-A-59-197857 (JP, A) JP-A-2-210257 (JP, A) JP-A-4-118555 (JP, A) JP-A-61-117450 (JP, A) Kaisho 59-163563 (JP, A)

Claims (1)

(57) [Claims] 1. A plurality of vertical probes arranged on a flat portion of each surface of four sides of a square billet, and a center of a beam at both ends of the flat portion of the square billet. An oblique probe arranged so as to face the side closer to the place, a plurality of transmission / reception circuits connected to the respective probes, and a plurality of gates for flaw detection echo output from the transmission / reception circuit. A gate circuit for determining whether or not there is a defect equal to or higher than a preset defect determination level, and a defect equal to or higher than the defect determination level based on the output of the gate circuit set at the center of the angular billet of the vertical probe. Was detected, the defect could not be detected by the gate circuit output of the vertical probe that detected the defect and the vertical probe that detected the same location from the direction rotated 90 degrees with respect to the cross section of the square billet. Time is above A central directional defect processing circuit for determining that the detected defect is a directional defect; and a defect detecting level equal to or higher than the defect determination level in the gate circuit output of the oblique probe. Is detected,
If the defect cannot be detected by the gate circuit output of the vertical probe that is flaw-detecting the same place from the direction rotated 90 degrees in the cross-sectional direction with the oblique probe that detected the defect, If the section in the center direction of the square billet adjacent to the location where the bevel probe detected the defect is the aforementioned directional defect from the result of the gate circuit output of the vertical probe, it is detected by the bevel probe An ultrasonic flaw detector for a square billet, comprising: a subcutaneous directional defect processing circuit for determining a detected defect as a directional defect.