JPS59120952A - Flaw detector for copying welded steel pipe - Google Patents

Abstract

PURPOSE:To improve the reliability and to make the device small-sized, simple, and low-cost, by propagating ultrasonic pulses along a weld line and providing a weld position detecting device on a common base coaxially. CONSTITUTION:A transmitting oscillator 3 and a receiving oscillator 4 are provided along the weld line of a weld 2 so as to face each other, and the ultrasonic beam radiated from the transmitting oscillator 3 is made incident to a welded steel pipe 1 at a prescribed angle and is propagated along the weld line while being reflected prescribed-number of times repeatedly on inside and outside tube walls 1A and 1B and is received by the receiving oscillator 4. Since the variance of the level of transmission pulses in the weld reaches about >=20dB which is >=10 times as high as that in a base material part 8 where there are no variance of thickness, defects, etc., the position of the weld is detected accurately. Since a weld position detecting device 20 is provided on a common base 50, displacement parallel with the axis of an electric welded steel pipe 1 corresponds to devices 20 and 40 in 1:1, and copying control of a flaw detector 40 is performed directly with a weld position signal, which the weld position detecting device 20 detects, for displacement around the axis of the pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copying type welded steel pipe welded part flaw detection apparatus, and more particularly to a copying type welded steel pipe welded part flaw detection apparatus that detects the welded part position of a welded steel pipe using ultrasonic waves. .

Generally, when performing ultrasonic flaw detection on welded parts of ERW steel pipes, in order to detect defects that occur in welded parts with a width of several millimeters without overlooking them, it is necessary to conduct ultrasonic flaw detection on the outer surface, inner surface, fleshy part, etc. of the welded part. <Ultrasonic beam must be incident. However, this ultrasonic beam usually has an effective beam width of only a few millimeters or less, and on the other hand, the position of the weld constantly changes, even if only slightly, while the welded steel pipe is being transported for inspection. It is most important to accurately maintain the relative position of the probes in order to improve the accuracy and reliability of the probe. This is the reason why it is necessary to accurately detect the position of the weld in order to make the inspection probe follow the changes in the position of the weld.

Conventionally, the position of the weld has been detected using an eddy current method that detects the difference in composition between the weld and the base metal, a heat detection method that detects the high temperature state of the weld, and a weld color (bluish color) of the weld. ), a number of methods have been tried, including color detection methods, but none of them have been practical or reliable. For example, an electric rope is usually annealed immediately after welding. With four tubes, the materials of the welded part and the base metal are almost equalized, making it difficult to use the eddy current method or color detection method, and it is also unnecessary to use the heat detection method after the sample has cooled. It is possible. For this reason, flaw detection of welded parts using the tracing method has no choice but to be carried out by visual inspection of the inspection probe or by manual operation using an industrial TV, etc., and the number of channels that takes into account tracing errors is required. There are disadvantages in that the reliability and reproducibility of the test are increased, and that the entire device becomes complicated and expensive. ! ! In addition, when performing weld flaw detection without using the tracing method, it is necessary to arrange in advance the number of inspection probes corresponding to the number of channels in anticipation of changes in the relative position of the weld line. However, it requires dozens of channels, making the equipment extremely large and the signal processing complicated.On the other hand, there is the disadvantage that testing a single tube after cutting is virtually impossible because the bath tangent position is undefined. Ta.

Therefore, in view of the shortcomings of the conventional technology, the inventors conducted extensive research in order to develop a highly practical and reliable profiling type welded steel pipe weld zone flaw detection device. It was discovered that the level of the transmitted pulse by ultrasonic transmission method changes significantly in the welded part, and the invention was made based on this knowledge.

That is, the present invention provides a welding position detection section with a transducer set including a transmitting and receiving transducer set, a means for scanning the transducer set in the circumferential direction of the welded steel pipe, and an ultrasonic pulse. The transmitted pulse is propagated parallel to the bath tangent line of the welded steel pipe, and changes in the reception level of the welded part relative to the base metal are detected (7) Means for obtaining welded part position information and welding by multiplying the information at this welded part with an offset It is an object of the present invention to provide a copy type welded steel pipe welded part flaw detection apparatus equipped with means for obtaining part center position information, thereby eliminating all the disadvantages of the prior art described above.

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 to 9.

FIG. 1 is a principle explanatory diagram for explaining a method for detecting a welded portion position of a welded steel pipe according to the present invention. In the figure, reference numeral 1 denotes an electric resistance welded steel pipe which is formed into a tubular shape from a coiled steel strip and then welded by high frequency resistance, and is annealed and bead cut after welding. A welded portion 2 forming a linear weld line along the tube axis direction is formed at the upper end edge of this ERW steel pipe 1. On the outer peripheral side of the ERW steel pipe work,
A transducer set 5 consisting of transmitting and receiving transducers 3 and 4 is equipped. The transmitting transducer 3 and the receiving transducer 4 are installed facing each other along the weld line of the welding part 2, and the pulsed ultrasonic beam σ emitted from the transmitting transducer 3 is
The welded steel pipe 1oτI is incident at a constant angle, and the inner and outer pipe walls I
After repeating reflection a predetermined number of times at A and IB and propagating through the weld line, the transmitted pulse is received by the receiving transducer 4. The effective beam width of the ultrasonic beam, the angle of incidence on the welded steel pipe 1, and the number of reflections within the pipe are determined experimentally to provide the best conditions.

The vibrator set 5 is configured to relatively rotate and scan the outer periphery of the welded steel v1 in the circumferential direction.

A typical example of a case where signals are transmitted and received by the local water immersion method under the above settings, and the transmitted pulse level is continuously recorded in analog form while the transducer paper 5 goes around the welded steel pipe 1. The waveform is shown in Figure 2. As is clear from the figure, a signal change occurs each time the vibrator paper 5 passes a weld, and it can be seen that a weld position signal can be obtained.

FIG. 3 shows the correspondence between the transmission pulse level change portion of the weld and the weld 2 in this weld position signal. The m-joint bead of the welded steel pipe 1 is cut with a flat cutter on the outer diameter side and a round cutter on the inner diameter side, so there are discontinuous cutter edge parts 6, 6.7, on the outer diameter side and on the inner diameter side, respectively, as shown in the figure. 7 occurs. The transmitted pulse level is slightly higher than that of the base metal part 8 at the cutter edge parts 6, 6 on the outer diameter side, and is significantly attenuated at the cutter edge part 7, 7 on the inner diameter side, and the inner and outer diameters are locally parallel in the center part. It rises again from doing. C is the center of welding. According to experiments, the change in the transmitted pulse level of the weld by this oblique axial transmission method reached approximately 2QdB or more compared to the transmitted pulse level of the base metal part 8, and the discrimination between the base metal part 8 and the weld part 2 was determined by vertical reflection. The value is an order of magnitude larger than that obtained using the method or oblique reflection method. This was discovered by chance as a result of various experiments conducted by the inventor.

On the other hand, as shown in Figure 8g2, the transmission level in the base material portion 8 only changes by 1 to 2 dB or less unless there is a special thickness change, defect, etc. Therefore, the weld position can be accurately detected based on the level change of the transmitted pulse by the oblique axial transmission method.

As mentioned above, the change in the transmitted pulse level of the weld zone is mainly caused by the local shape change of the weld zone 2, and depending on how the weld bead is cut, the pattern shown in FIG. 4 or 5 may occur. However, in both cases, the difference from the base metal level is significant, and the center position C of the weld can be easily detected by applying appropriate signal processing. Further, even when the vibrator paper is fixed and the electric resistance welded steel pipe is rotated, the weld position can be similarly detected.

Next, a copying method using the weld position detection method described above
The welded part flaw detection device for fiL sewn steel pipes will be explained based on FIGS. 61 to 9. FIG. 6 is a schematic diagram showing a copying type electric resistance welded steel pipe welded part flaw detection apparatus 10.

In the figure, an electric resistance welded steel pipe 1 as an object to be inspected, which has been swamped in the direction of the pipe axis, resistance welded, peed cut, and annealed, is being conveyed to the right from the paper surface pressure. . A welding position detecting device 20 as a welding position detecting section is provided on the upstream side so as to surround the electric resistance welded steel pipe 1 from the outside. Flaw detection devices 40 are installed at positions close to each other on the downstream side. The welding part position detection unit [20 is composed of a device main body 21, a rotary cylinder 22 rotatably supported within the device main body 21, and a rotation drive unit 23 for rotationally driving the rotary cylinder 22. has been done.

The rotary cylinder 22 includes a cylindrical portion 24 and a disk-shaped adapter 25 fixed to the left end of the cylindrical portion 24 with a bolt or the like. This adapter 25vC is provided with a vibrator holder 27 via a support arm 26. This vibrator holder 27 has a longitudinal cross section formed in a partially annular shape with a narrow width.
A vibrator paper 3o consisting of transmitting and receiving vibrators 28 and 29 arranged along the tube axis of the electric resistance welded steel pipe l is provided on the top. This transducer paper 30 has a function of transmitting and receiving ultrasonic pulses by the oblique axial transmission method described in (7). The transducer holder 27 is installed at a distance between the transmission and reception transducers 28 and 29 of the transducer holder 27, and the electric resistance welded steel pipe 1 is partially immersed in water by degassed water forcibly supplied from the adapter 25. The support arm 26
A roller (
(not shown) is equipped. This support arm 26 is always urged in the direction of the ERW steel pipe 1 by a follow-up mechanism (not shown) provided on the adapter 25 side, and therefore, for some reason, the tube axis of the ERW steel pipe 1 moves in parallel. In this case, the support arm 26 responds to maintain a constant distance between the vibrator holder 27 and the electric resistance welded steel pipe 1. The rotary drive section 23 has a servo motor, and the rotational force of the servo motor is transmitted to the rotary cylinder 22 via a belt 31'ff. Thereby, the rotating cylinder 22 is rotated at a predetermined speed. The rotation drive unit 23 includes an electromagnetic coupling unit for timing the rotation tube 22 to pass through the reference position, a water supply coupling unit for supplying the degassed water, and the like. These components have substantially the same configuration as a well-known rotary ultrasonic flaw detector, and the details will be omitted. In the welded portion position detection device 20 configured as described above, when the ERW steel pipe 1 passes through the inner diameter side of the rotating tube 22, the vibrator set 30 rotates around the ERW steel pipe 1. Using the local water immersion method, the entire area is continuously scanned to detect the position of the weld.

The flaw detection device 40 includes a device main body 41 and a device main body 4.
The rotary cylinder 42 is rotatably supported within the rotary tube 1, and a rotary drive section 43 for rotationally driving the rotary cylinder 42. The rotating cylinder 42 consists of a cylindrical part 44 and a disk-shaped adapter 45 fixed to the right end of the cylindrical part 44, and the adapter 45 has the support arm 26. A support arm 46 configured in substantially the same manner as the vibrator holder 27. A probe holder 47 is provided. This probe holder 47 has a partially annular cross section, and is used to inspect the welded portion 2 (see Fig. 1) of the ERW steel pipe 1 for defects. Probes 48, 48 . with the minimum required number of channels. A probe group 49 consisting of... is provided. This probe holder 47 is provided a short distance from the surface of the electric resistance welded steel pipe 1, and is connected to the adapter 45.
The degassed detection water supplied from
8, . . . and the electric resistance welded steel pipe 1 are locally flooded with water. Like the support arm 26, the support arm 46 is adapted to respond to the parallel movement of the electric resistance welded steel pipe l with respect to the tube axis by a tracking mechanism. The rotation drive unit 43 is a servo motor, and this servo motor and the rotation cylinder 42
are connected by a belt 39. The VC is configured such that a servo motor is driven and controlled based on the welding part position signal sent from the welding part position detection device 20, so that the rotary cylinder 42 is rotated by a predetermined amount as necessary. The probe group 49 provided on the holder 47 can follow the positional change (rotation change) of the welded part 2 C.
There is. This rotary cylinder 42 is tapered by t so that it can rotate ±180° and perform a tracking operation. The rotation driving section 43 (() is provided with a current position generating section of the rotation tube 42. The device main body 41 is provided with a flaw detection water supply coupling section for supplying the flaw detection water. Ori,
Further, the rotating tube 42 is provided with predetermined wiring for transmitting and receiving signals from the probe 7 group 49, and is connected to an external processing device via a cable 7.

In the flaw detection device 40 configured in this way, the electric resistance welded horizontal pipe 1
When the probe group 4 passes through the inner diameter side of the rotating tube 42, the probe group 4
9 follows changes in the weld line (2) The weld is continuously inspected for defects using the local water immersion method.

The bath contact position detection device 20, the flaw detection device 40id, and the respective rotary tubes 22 and 42 are arranged so as to be coaxial with each other, and are fixed on a common base 50. has been done. This base 50 can be raised and lowered by manual operation. 1 piece of electric resistance welding horizontal pipe, welding part f-plane detection device 20
The flaw detection device 40 is conveyed by feed rollers 71 and 72 provided in front of the flaw detection device 40 and at the rear of the flaw detection device 40 . During transportation, the ERW steel pipe 1 may undergo rotational displacement around the tube axis or displacement in a direction parallel to the tube axis (perpendicular to the conveyance direction) for some reason. Of the displacements that occur in the ERW horizontal tube 1, the displacement parallel to the tube axis 7 [with respect to displacement -
C The support arm 26 is configured to perform a follow-up operation, but during this follow-up operation, the vibrator holder 27 may be rotationally displaced relative to the rotary cylinder 22, and this may result in 'd Even if there is no displacement around the tube axis in the sewing tube 1 itself, the welding area t? There is a risk of false detection. The first step in eliminating such false detections requires extremely complicated signal correction processing, and the amount of parallel displacement of the ERW steel pipe 1 with respect to the pipe axis (the weld position detection device 2
0 and the flaw detection device 40 are each mounted on separate bases, the amount of parallel displacement of the ERW steel pipe l at each device position will not be the same). It is almost impossible in practice. In this regard, when the weld position detection device 20 and the flaw detection device [40] are installed on the common base 50, the displacement parallel to the tube axis of the ERW steel pipe l will be 1:1, and the support arm 26.
As a result, the relative rotation amounts of the transducer holder 27 and the probe holder 47 with respect to the rotary tube 22 and the rotation m42 are also the same, and the detection error of the weld position is canceled out. Become. Therefore, the displacement parallel to the pipe axis of the ERW steel pipe l can be ignored, and the flaw detection device 4 can directly detect the displacement around the pipe axis using the weld position signal detected by the weld position detection device 20.
Following the example of 0, the control can be omitted.

FIG. 7 is a block diagram showing an example of an electrical configuration for performing tracing control based on the weld position signal 1. In the figure, the transducer paper 30 of the weld position detection device 20 is Transmission/reception circuit 51 (#) is operated to transmit and receive ultrasonic pulses based on the oblique axial transmission method. This transducer paper 30 rotates around the ERW steel pipe 1 at a predetermined speed and continuously scans it. .

The ultrasonic transmitter/receiver 51fd converts the change in the transmitted pulse level received by the receiving transducer 29 into a continuous analog signal and outputs it as a welding position analog signal. This weld position analog signal has the shape shown in FIG. 4, for example, depending on the state of the bead cut, and is waveform-shaped by the waveform shaping circuit 52 to obtain a pulsed weld position signal. On the other hand, each time the reference point in the circumferential direction of the rotary tube 22, for example, the position of the vibrator paper 30 in a state where the tracking mechanism of the support arm 26 has returned to its original position, passes through the ceiling position due to the rotation of the rotary tube 22, , the reference position passage timing generating section 80 generates all pulsed reference position signals.

Next, the counter circuit 53 counts clock pulses for position and angle counting output from the clock generation circuit 54 from when the reference position signal is input manually until when the welding position signal is input, and the target value signal (welding position detection (See Figure 8).

The flaw detection device 40 performs feedback control on the servo motor of the rotary drive unit 43 based on the target value signal sent from the weld position detection device 20, and causes the probe group 491r to follow the change in the weld position. To explain this feedback control in detail, the current position generating section of the rotation drive section 43 is a reference point in the circumferential direction of the rotation tube 420, for example, the center point of the probe holder 47 when the support arm 46 returns to its original position. Generates a rotation amount signal (controlled amount signal) from the ceiling position. And this time due to feedback! JJ amount is detected by welding position detection device 2
The servo motor is compared with the target value sent from 0 and the servo motor is controlled so that the two match.

By the way, when the welding part position analog signal has the waveform shape shown in FIG. 4, the rising timing of the output pulse of the waveform shaping circuit 52 is earlier than the center position of the welding part 2, and as a result, the waveform shown in FIG. As shown in (1), the target value θ, which is the output of the counting circuit 53, deviates from the actual center position of the welding part 2. Therefore, if the flaw detection position 40 is directly controlled by the output of the counting circuit 53, a tracing error of Δθ will occur as shown in FIG. 9 (2).

To eliminate this error, an offset circuit 55 is provided on the output side of the counting circuit 53. To explain the function of this offset circuit 550, the offset amount of the offset circuit 55 is set to zero without switching, and the flaw detection device 40 is controlled by the target value signal outputted from the counting circuit 53. At this time, as described above, a tracing error occurs by lθ. Next, manually operate the offset circuit 55 to offset the target value by Δθ while finely adjusting the offset amount.
By visual inspection, the pointer 60 installed in the center of the probe holder 47 is aligned with the center position of the welded part 2. Once the offset operation of the target value is completed in this way,
Thereafter, the target value signal that is the output of the counting circuit 53 is automatically corrected by the offset circuit 55, and is outputted to the flaw detection apparatus 40 as a modified +E target value signal. This allows accurate tracing control of the flaw detection device 40.

According to the embodiment described above, by propagating the ultrasonic pulse for detecting the position of the weld along the weld line direction, an extremely large difference in the level of the transmitted pulse can be obtained between the base material and the weld. Moreover, accurate weld position detection can be performed under any device installation conditions without any restrictions on the temperature of the electric resistance welded steel pipe that is the material to be inspected, the presence or absence of heat treatment, two-color change, etc. Therefore, it is possible to perform highly reliable defect inspection by simply equipping the flaw detection device with the minimum number of channels required.7'J1. The device can be made smaller, simpler, and less expensive. In addition, since the weld position detection device is installed coaxially on a common base, there will be no error even if the ERW steel pipe is displaced parallel to the pipe axis. 7 [Leprosy can be controlled. Furthermore, by manually applying a predetermined amount of offset to the weld position information to obtain the weld center position information, the number of channels of the flaw detection device can be reduced, making it possible to reduce the number of channels of the flaw detection device and create a highly accurate and practical tracing-type detector with an extremely simple configuration. A flaw detection device for welded parts of sewn steel pipes is obtained.

In the above embodiment, an electric resistance welded steel pipe was used as the test material, but other welded steel pipes may be used as long as they have a straight weld line.

As described above, according to the present invention, it is possible to precisely trace the change in the center position of a welded part with a simple configuration, and therefore, a highly practical and reliable tracing type welded steel pipe welded part flaw detection device is provided. Obtainable.

[Brief explanation of drawings]

FIG. 1 is a principle 1 explaining the weld position detection method according to the present invention, FIGS. 2 to 5 are diagrams explaining the operation of FIG.
The figure is a schematic front view showing a welded part flaw detection device for a copying type electric resistance welded I4 pipe according to the present invention. A timing chart showing the operation, FIG. 9 is an explanatory diagram of the operation of FIG. 7. DESCRIPTION OF SYMBOLS 1... ERW steel pipe, 2... Welded part, 5, 30... Vibrator set, 8... Base metal part, 10... Copy type ERW steel pipe welded part flaw detection device, 20.・Bath contact position detection device, 22・
...Rotating tube, 23... Rotating drive section, 40... Flaw detection device, 53... Counting circuit, 55... Offset circuit. Patent applicant Tokyo Keiki Co., Ltd. (+1 or 1 person) agent
Isamu Takahashi, Bentanshi Figure 2 Figure 3 Figure 4 Figure 5 2-6 Otemachi, Chiyoda-ku, Tokyo, No. 3 Procedural amendment (voluntary) March 14, 1980 Patent Office Commissioner Kazuo Wakasugi Tono 1 , Indication of the case 1982 Patent Application No. 227384 2. Title of the invention 2-16-46 Minami Kamata, Ota-ku, Tokyo Name (338) Tokyo Keiki Representative Shunsuke Kono Address 2-6-3 Otemachi, Chiyoda-ku, Tokyo Name (338)
(665) Nippon Steel Corporation Representative Takeshi 1) Yutaka 4, Agent 16410003) 361-0819
Name Patent Attorney (7916) Takahashi! I! ! l]
K',,'j:I: 17:5, The specification and drawing 6 to be amended, the content of the amendment (I), and Figures 2 and 3 of the attached drawings are corrected as shown in the attached sheet. (2) Regarding page 7 of the specification, the following amendments have been made. ■ Delete "flat shape" in the 11th line and insert "round shape with large curvature" in the deleted place. ■ Insert "small curvature" between "inner diameter side" and "round cutter" in the 12th line. ■ Delete "rise" in the 16th line and insert "decay" in the deleted place. ■ In line 17, between “7.7” and “significantly”,
[Due to the principle of a concave mirror, it rises and the inner and outer diameters become non-parallel at the inner cutter, so insert the that's all

Claims (2)

[Claims] (1) In a copying type welded steel pipe welded part flaw detection device that has a welded part position detection part of a welded steel pipe and performs a copying control operation based on the welded part position information outputted by this welded part position detection part,
The welded portion position detecting section V includes a transducer set consisting of transmitting and receiving transducer sets, means for scanning the transducer set in the circumferential direction of the welded steel pipe, and means for transmitting ultrasonic pulses to the welded steel pipe. A means for obtaining weld position information by transmitting the transmitted pulse parallel to the bath tangent and detecting changes in the reception level of the weld with respect to the base metal, and a means for obtaining weld position information by applying an offset to this weld position information. A tracing type welded part flaw detection device for a welded steel pipe, characterized in that it is equipped with means for obtaining information. (2) In a copying type welded steel pipe welded part flaw detection device that has a welded part position detection section for welded steel pipes and performs a copying control operation based on the bath contact position information outputted by this welded section position detection section, The welded portion position detecting unit includes a transmitting and receiving transducer set or a transducer set, a means for scanning the transducer set in the circumferential direction of the welded steel pipe, and a means for scanning the transducer set in the circumferential direction of the welded steel pipe. A means for obtaining weld position information by transmitting the incident beam parallel to the weld line of a welded steel pipe and detecting a change in the reception level of the weld with respect to the base metal of the transmitted nozzle, and a means for obtaining weld position information by applying an offset to the weld position information. 1. A tracing-type welded steel pipe welded part flaw detection apparatus, characterized in that said welded part position detection part and said welded part probe part are mounted on a common base, and said welded part position detection part and said welded part probe part are equipped on a common base.