JP2985740B2 - Pipe end detector for automatic flaw detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tube for an automatic flaw detector in which a tube end is continuously conveyed in a contact state in a non-destructive inspection line for the purpose of quality assurance of a steel tube. The present invention relates to an edge detection device.

[0002]

2. Description of the Related Art Ultrasonic flaw detectors are used for inspection of surface defects of welds or inner and outer surfaces for the purpose of quality assurance of steel pipes.
As an automatic flaw detector such as a magnetic flaw detector, for example, an automatic ultrasonic flaw detector is often a probe rotating type. For a long material such as a steel pipe, particularly a small-diameter one, a method of detecting a flaw while continuously sending a pipe end to a flaw detector in an end-to-end state in order to improve the flaw detection capability. Is generally adopted.

[0003] In the case of ultrasonic flaw detection, in order to suppress spurious echoes when the ultrasonic flaw detection probe detects the contact surface between the pipe ends of the steel pipe as an excessive end face signal, flaw detection is performed on the front and rear end faces of each steel pipe. The flaw detection operation or flaw detection evaluation function of the machine is automatically ON-OFF controlled. Ideally, flaw detection should be performed to the rear end position just before the occurrence of a pseudo echo, then the flaw detection function should be cut off, and tube end control to start flaw detection again from the very front end position where flaw detection is possible is the quality. This is important for assurance. Thus, END
To detect the pipe end contact surface of TO END with high accuracy and send it to the signal processing unit of the ultrasonic flaw detector to improve the precision of the pipe end control and the reliability of automatic sorting for discriminating good and defective steel pipes This is an important point in performing flaw detection.

The above-mentioned tube end contact surface is detected by detecting the tube end with a photoelectric switch or a proximity switch before the tube end is brought into contact with the tube end, and using a pulse generator to generate a distance pulse or a fixed clock pulse. A tracking method using a signal, a method of detecting a tube end contact portion using a tube end detector, and the like are known.

[0005] As a method of detecting the pipe end of the pipe end contact portion,
A vortex flow method using a penetrating coil, a method of extracting a pipe end detection signal from a pipe end detector as a pipe end detection signal only in the vicinity of a pipe end contact portion based on a steel pipe moving distance signal and set pipe length data (Japanese Patent Laid-Open No. 59-12354) ).

[0006]

As shown in FIG. 6, the eddy current method using the penetrating coil is used to remove the pipe end contact portions of the steel pipes P ₁ , P ₂ , P ₃ ... The signal is detected by the penetrating coil 61, and a signal processing unit 62 outputs a tube end detection signal to a signal processing unit 63 of the ultrasonic flaw detector. Further, the pulse generator 64 outputs a distance pulse corresponding to the transport speed of the steel pipe to the signal processing unit 63 of the ultrasonic flaw detector. The probe rotating unit 65 of the ultrasonic flaw detector detects inner and outer surface defects of the steel pipe and outputs the detected defects to the signal processing unit 63. The signal processing unit 63 of the ultrasonic flaw detector uses the flaw detection data input from the probe rotating unit 65 to transfer the pipe end detection signal input from the signal processing unit 62 of the penetrating coil 61 to the steel pipe input from the pulse generator 64. Tracking is performed by a distance pulse corresponding to the speed, the tube end control is performed, and a marking signal 66 and an automatic selection signal 67 are output.

[0007] Eddy-current process by the encircling coil, as shown in FIG. 7, the inner quality defect ID of the flaw steel pipe P ₁ is not detected in the through coil 61 and the signal processing section 62, the surface defects of the test object the steel pipe P ₂ SD (opening defect, large cover defect) is erroneously detected as a tube end detection signal. That is, in the eddy current method using the penetrating coil, it is impossible to distinguish between a tube end detection signal that detects a true tube end contact surface and a signal that detects a surface defect SD (opening defect, large cover defect). For this reason,
The pipe end detection signal is tracked to control (blank) the pipe ends at the front and rear ends of the steel pipe. The signal processing unit 63 of the ultrasonic flaw detector, the test object the steel pipe P ₂ surface defects SD
Is detected as a pipe end detection signal, and the steel pipe P ₂ to be inspected is P _2a , P _2b
And the flaw detection output is in a form in which the original surface defect SD is blanked. If flaw is finished, good, automatic sorting of defective products is carried out by automatic sorting signal 67 output of the signal processing unit 63 of the ultrasonic flaw detector, test object the steel pipe P ₂ are outflow defective products are selected to be non-defective Will do. A defective portion in the inner quality defect ID of the flaw steel pipe P _1, marking command 66 from the signal processing unit 63 of the ultrasonic flaw detector is outputted, will be sprayed marking, surface defects S of test object the steel pipe P ₂
D is not spray-marked because the pipe end is controlled (blanked). In addition, in the eddy current method using the penetrating coil, if the outer diameter of the steel pipe is changed, it is necessary to replace the penetrating coil 61 and adjust the sensitivity of the signal processing unit 62, which places a burden on the operator.

Further, the method disclosed in Japanese Patent Application Laid-Open No. 59-12354 discloses a method of detecting a pipe end detection signal from a pipe end contact surface detector.
Only the vicinity of the pipe end contact portion can be extracted as a pipe end detection signal based on the distance signal corresponding to the transfer speed of the steel pipe and the set pipe length data. Malfunction of the tube end detection unit can be checked using the signal near the tube end contact portion, and a flaw signal near the tube end contact portion is output as an abnormal signal. In the method disclosed in Japanese Patent Laid-Open No. 59-12354, this abnormal signal requires the line to be stopped and re-inspected, which places a burden on the operator. In addition, it is not possible to discriminate whether the signal detected near the tube end contact portion is a signal that has detected a true tube end contact surface or a signal that has detected a surface defect SD. Further, the method disclosed in Japanese Patent Application Laid-Open No. Sho 59-12354 is difficult to input into a pipe length setting device each time the length of a steel pipe to be flawed changes, and to re-examine a steel pipe having an abnormal signal. As in the eddy current method, the burden on the operator is increased.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art, and to detect an end of an automatic flaw detector of an automatic flaw detector which can be operated unattended except for changing the outer diameter and thickness of a steel pipe and intervening an operator in sensitivity calibration. Is to provide.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object. As a result, it was confirmed that by using a plurality of probe coils instead of the conventional through coil type tube end detector and forming an AND circuit with each probe coil, it is possible to distinguish the tube end contact portion from the surface defect, The invention has been reached.

That is, the present invention relates to a pipe end detecting device for an automatic flaw detection line for automatically flaw detecting a steel pipe continuously conveyed in a state where the pipe ends are in contact with each other. Two or more probe-type sensors are provided at different angles, and the output of each probe-type sensor is ANDed.
A tube end detecting device of an automatic flaw detector, wherein a circuit is formed and a signal of a tube end contact surface is taken out separately from surface flaws other than the tube end contact surface.

Also, in a pipe end detecting device of an automatic flaw detection line for automatically flaw detecting a steel pipe continuously conveyed in a state where the pipe ends are in contact with each other, the angle is changed in the circumferential direction of the steel pipe upstream of the flaw detector. Two or more probe-type sensors are provided at different positions and at different mounting positions in the pipe axis direction, and the deviation of the distance between each probe-type sensor is determined by the distance signal of the distance detector that detects the moving distance of the steel pipe. Automatic flaw detection wherein a shift register for correction is provided, an AND circuit is formed from the output of each probe type sensor and the output of the shift register, and a signal at the tube end contact surface is taken out separately from surface defects other than the tube end contact surface. It is a pipe end detecting device of the machine.

As the probe type sensor used in the present invention, a probe coil used for an eddy current flaw detection test is used. If the outer diameter of the steel pipe P to be flawed is relatively large, it is arranged to face the flaw detection line in the pipe axis direction. . When the outer diameter of the steel pipes P to be detected is small, the interference is avoided by disposing the probe coils at a small distance, for example, 100 mm in the pipe axis direction without facing each other. However, in this case, it is necessary to correct the deviation of the distance placed apart by the distance signal of the distance detector for detecting the moving distance of the steel pipe and the shift register.

Further, the gap between the probe coil and the surface of the steel pipe can be always kept constant by holding the probe holder of the probe coil via a follow-up roller that comes into contact with the surface of the steel pipe. Furthermore, when using a probe holder in which the gap between the probe coil and the steel pipe surface is always constant by the following roller, if the probe holder is adjusted only when the outer diameter of the pipe changes, the probe coil can have a constant sensitivity and the burden on the operator is reduced. This can be reduced, and the pipe end contact surface signal is not output due to the surface defect SD of the steel pipe.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of a pipe end detecting device of an automatic flaw detector according to the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram systematically showing an automatic ultrasonic flaw detector for steel pipes using the pipe end detecting device of the automatic flaw detector of the first embodiment of the present invention, and FIG. 2 is a block diagram of the automatic flaw detector of the second embodiment of the present invention. FIG. 3 is a block diagram systematically showing an automatic ultrasonic flaw detector for a steel pipe using a pipe end detection device, FIG. 3 is an explanatory view of a gap L between a probe coil and a steel pipe surface, and FIG. 4 is a gap L between a probe coil and a steel pipe surface. FIG. 5 is a time chart of signals of various parts of the automatic ultrasonic flaw detector of FIG. 2.

In FIG. 1, reference numeral 1 denotes a probe rotating unit of the ultrasonic flaw detector, and 2 denotes a signal processing unit of the ultrasonic flaw detector, which receives a flaw signal and a tube end contact surface signal from the probe rotating unit 1. Reference numeral 3 denotes a pulse generator for detecting a moving distance of the steel pipe, and outputs a clock pulse signal proportional to the moving distance of the steel pipe to the signal processing unit 2. 4a and 4b are probe rotating parts 1
The probe coils 4a and 4b are conveyed to the probe rotating unit 1 of the ultrasonic flaw detector by the conveying roller 5 in a state where the tube ends are in contact with each other, and are arranged on the upstream side of the probe coil so as to face in the tube axis direction of the flaw detection line. The front and rear ends of the steel pipes P ₁ , P ₂ , P ₃ to be inspected and the pipe end contact surfaces 6, 7 and the surface defect SD are detected and output to the signal processing units 8a, 8b. Reference numeral 9 denotes an AND circuit for signals from the signal processing units 8a and 8b.
When the detection signals are simultaneously inputted from a and 8b, a true tube end contact surface signal 10 is output to the signal processing unit 2.

The signal processing unit 2 is proportional to the flaw detection data input from the probe rotation unit 1, the true pipe end contact surface signal 10 input from the AND circuit 9, and the moving distance of the steel pipe input from the pulse generator 3. It is configured to output a marking signal 11 and an automatic selection signal 12 based on the clock pulse signal thus obtained. Probe coil 4a, 4b
As shown in FIG. 3 and FIG. 4, the probe holder 14 so that the lift-off amount L (gap between the steel pipe P to be inspected and the probe coil) follows the steel pipe P to be inspected by the follow-up roller 13 and is always kept constant. It is supported by. Further, in the case of using the probe holder 14 in which the lift-off amount L of the probe coil from the surface of the steel pipe P to be inspected by the follower roller 13 is always constant, if the probe holder 14 is adjusted only when the pipe outer diameter changes, the probe coil 4a, 4b
The sensitivity may be constant, the burden on the operator can be reduced, and the pipe end contact surface signal 10 is not output due to the surface defect SD of the steel pipe.

With the above configuration, when the detection signals are simultaneously input from the signal processing sections 8a and 8b to the AND circuit 9, the AND circuit 9 outputs the true tube end contact surface signal 10
Is output to the signal processing unit 2. The signal processing unit 2 detects flaw detection data input from the probe rotation unit 1, a true pipe end contact surface signal 10 input from the AND circuit 9, and a clock pulse proportional to the moving distance of the steel pipe input from the pulse generator 3. A marking signal 11 and an automatic sorting signal 12 are output based on the signals. Further, the probe coil 4a or 4b
Detects a surface defect of the steel pipe P to be inspected, and the detection signal is input to the AND circuit 9 from the signal processing unit 8a or 8b, the AND circuit 9 generates the signal processing unit 8a or 8b of the probe coil 4a or 4b. Since the true tube end contact surface signal 10 is not output to the signal processing unit 2 unless a detection signal is input simultaneously from the, the marking signal 11 and the automatic sorting signal 12 can be accurately output, and the surface of the steel pipe P to be detected The defect is not overlooked, and even if it is a surface defect near the tube end contact surface, it is not erroneously determined.

In FIG. 2, reference numeral 1 denotes a probe rotating unit of the ultrasonic flaw detector, and 2 denotes a signal processing unit of the ultrasonic flaw detector, which receives a flaw signal and a tube end contact surface signal from the probe rotating unit 1. Reference numeral 3 denotes a pulse generator for detecting a moving distance of the steel pipe, and outputs a clock pulse signal proportional to the moving distance of the steel pipe to the signal processing unit 2. Reference numerals 15a and 15b denote small distances, for example, 100 mm, which can avoid mutual interference without being opposed to the upstream side of the probe rotating unit 1 in the tube axis direction of the flaw detection line.
With the probe coils spaced apart, the probe coil 15
Reference numerals a and 15b denote front and rear ends of the steel pipes P ₁ , P ₂ , and P ₃ conveyed to the probe rotating unit 1 of the ultrasonic flaw detector by the conveying roller 5 while the pipe ends are in contact, and the pipe end contact surfaces 6 and 7. In addition, a surface defect is detected and output to the signal processing units 16a and 16b. 17 is a pulse generator dedicated to the tube end contact surface,
A clock pulse signal proportional to the moving distance of the steel pipe is output to the shift register 18.

The shift register 18 uses the clock pulse signal, which is input from the pulse generator 17 and is proportional to the moving distance of the steel pipe, to detect the steel pipe P ₁ ,
The AND circuit 1 corrects the detection signals of the front and rear ends and the tube end contact surfaces 6, 7 of P ₂ and P ₃ and the surface defect by correcting the distance deviation.
9 is output. Similarly, the AND circuit 19 receives the detection signals of the front and rear ends and the tube end contact surfaces 6 and 7 of the steel pipes P ₁ , P ₂ and P ₃ to be inspected from the signal processing unit 16b and the surface defect. The AND circuit 19 outputs a true tube end contact surface signal 20 to the signal processing unit 2 when the detection signals are simultaneously input from the signal processing unit 16b and the shift register 18. Signal processing unit 2
Is the flaw detection data input from the probe rotating unit 1 and A
A marking signal 2 based on a true pipe end contact surface signal 20 input from the ND circuit 19 and a clock pulse signal input from the pulse generator 3 and proportional to the moving distance of the steel pipe.
1. It is configured to output an automatic selection signal 22.

With the above configuration, FIG.
As shown in FIG. 7, the shift of the distance between the probe-type sensors 15a and 15b is corrected by the shift register 18, and the AND circuit 1 is output from the signal processing unit 16b or the shift register 18.
When the detection signals are simultaneously input to 9, the AND circuit 19 outputs a true tube end contact surface signal 20 to the signal processing unit 2. The signal processing unit 2 detects flaw detection data input from the probe rotation unit 1, a true pipe end contact surface signal 20 input from the AND circuit 19, and a clock pulse proportional to the moving distance of the steel pipe input from the pulse generator 3. A marking signal 21 and an automatic selection signal 22 are output based on the signals.

One of the probe coils 15a and 15b detects a surface defect of the steel pipe P to be inspected, and a signal processing section 16b
Alternatively, even if the detection signal is input from the shift register 18 to the AND circuit 19, the AND circuit 19 is connected to the signal processing unit 16b.
Alternatively, unless the detection signal is simultaneously input from the shift register 18, the true tube end contact surface signal 20 is not output to the signal processing unit 2, so that the marking signal 21 and the automatic selection signal 22 can be output accurately, and The surface defect of the steel pipe P is not overlooked, and even if the surface defect is near the pipe end contact surface, it is not erroneously determined. The detection of the surface defect of the steel pipe as the pipe end contact portion is prevented, and the abnormal signal is detected. Line stoppage due to erroneous determination such as does not occur.

[0023]

EXAMPLE While an ERW welded steel pipe having an outer diameter of 19 to 180 mm and a pipe length of 4 to 15 m was transported at a transport speed of 35 to 65 m / min, the pipe end contact surface was detected by the apparatus configuration shown in FIG. 5MHz ultrasonic search frequency while performing tube end control
The ultrasonic inspection test was carried out. As a result, there is no trouble such as a line stoppage due to a malfunction of the automatic sorting which has occurred in the past 4 cases / year, and the reliability of detecting the pipe end contact surface has been improved.
It has been confirmed that in addition to improving the pipe end control accuracy, it greatly contributes to reducing the burden on the operator.

[0024]

As described above, according to the present invention,
When carrying out ultrasonic inspection by continuously transporting the pipe ends of the steel pipes in contact with each other, line stoppage occurs due to erroneous determination of abnormal signals etc. near the pipe end contact surface without overlooking the surface defect of the steel pipe Without this, ultrasonic testing can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram systematically showing an automatic ultrasonic flaw detector for a steel pipe using the pipe end detecting device of the automatic flaw detector according to the first embodiment of the present invention.

FIG. 2 is a block diagram systematically showing an automatic ultrasonic flaw detector for a steel pipe using the pipe end detecting device of the automatic flaw detector according to the second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a gap L between a probe coil and a steel pipe surface.

FIG. 4 is an explanatory view of a mechanism for keeping a gap L between a probe coil and a steel pipe surface constant.

FIG. 5 is a time chart diagram of signals of respective parts of the automatic ultrasonic flaw detector of FIG. 2;

FIG. 6 is a block diagram systematically showing a conventional automatic ultrasonic flaw detector for steel pipes using a pipe end detector of an automatic flaw detector.

FIG. 7 is a time chart of signals of respective parts of the automatic ultrasonic flaw detector of FIG. 6;

[Explanation of symbols]

1, 65 probe rotating unit 2, 63 signal processing unit 3, 17, 64 pulse generator 4a, 4b, 15a, 15b probe coil 5 transport roller 6, 7, tube end contact surface 8a, 8b, 16A, 16b, 62 signal processing unit 9, 19 the AND circuits 10 and 20 pipe end contact surface signals 11,21,66 marking signal 12,22,67 automatic sorting signal 13 following roller 14 probe holder 18 shift register 61 through coil P _1, P _2, P ₃ test object Steel tube ID Internal defect SD Surface defect

──────────────────────────────────────────────────の Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01B 7/00-7/34 102 G01B 17/00-21/32 G01N 29/00-29/28

Claims (2)

(57) [Claims] In a tube end detecting device of an automatic flaw detection line for automatically flaw detecting a steel tube continuously conveyed in a state where the tube end is in contact with the tube end, a circumferential angle of the steel pipe is changed to an upstream side of the flaw detector. Two or more probe-type sensors are provided at the same position, an AND circuit is formed with the output of each probe-type sensor, and a tube-end contact surface signal is taken out separately from surface defects other than the tube-end contact surface. Pipe end detector for flaw detector. 2. A pipe end detecting device for an automatic flaw detection line for automatically flaw detecting a steel pipe continuously conveyed in a state where the pipe end is in contact with the pipe end, the angle of which is changed in the circumferential direction of the steel pipe upstream of the flaw detector. Two or more probe-type sensors are provided at different positions and at different mounting positions in the pipe axis direction, and the deviation of the distance between each probe-type sensor is determined by the distance signal of the distance detector that detects the moving distance of the steel pipe. Automatic flaw detection wherein a shift register for correction is provided, an AND circuit is formed from the output of each probe type sensor and the output of the shift register, and a signal at the tube end contact surface is taken out separately from surface defects other than the tube end contact surface. Pipe end detector.