JPH04122811A - Device for monitoring bead cutting abnormality on surface within pipe - Google Patents

Abstract

PURPOSE:To enable quality to be stable by mounting at least two supersonic probes to a frame which relatively performs automatic tracing of a welded part in pipe-axis direction for performing on-line measurement of abnormality in cutting shape of a seam welded pipe bead part easily and accurately. CONSTITUTION:In a process where a seam welded pipe 1 travels in the direction of the arrow, a thickness of a bead is detected by tracing supersonic probes 3A - 3C at a specified position and through contacting media, for example, water columns 4, 4... by a controller 21. In this process, if there is an abnormal point in thickness (x mark) at a central part of a welded line, only the thickness value from the supersonic probe 3B is changed. On the other hand, since the supersonic probe 3A always watches a base materials part, the value is always constant. Then, an operator 6A calculates difference between a thickness value a from the supersonic probe 3A and the b from the supersonic probe 3B and calculates the difference absolute value Z = ¦a-b¦ and the difference absolute value Z' = ¦a-c¦ with the thickness value from the supersonic probe 3C continuously. Then, if the absolute value Z or Z' exceeds a reference deviation value at comparison setters 7A and 7B, it is determined that cutting abnormality resulted and a location of failure is indicated by a proper alarm 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an apparatus for detecting an abnormality in the cutting shape of a weld bead on the inner surface of a tube, particularly an abnormality in cutting the inner surface, using an ultrasonic thickness gauge in a production line for electric resistance welded tubes.

[Conventional technology]

As is well known, ERW pipes are manufactured by rolling a copper strip into a tubular shape, welding the abutting portions from the inner and outer surfaces of the tube, and then cutting the inner and outer beads. It is required for quality assurance that both the outer surfaces be smooth.

Of these, cutting the outer surface of the tube is extremely easy, and it can be smoothed to the extent that it cannot be visually distinguished from the surrounding (base material).
Cutting the inner surface of a tube is not easy, and it is difficult to achieve a completely smooth cut, and it is impossible to confirm the cut shape by visual observation.

Conventionally, a method using an ultrasonic thickness gauge has been adopted as a method for online detection of the cut shape of the pipe inner surface. In this method, the outer surface of the ERW pipe after cutting is extremely smooth as described above, so if the thickness distribution of the pipe after cutting the outer surface is measured using an appropriate method with an ultrasonic thickness meter, the measured value This method takes advantage of the fact that it indicates the inner surface shape of the tube.

Conventionally, as a detection device for the cutting shape of the inner surface of a tube using such an ultrasonic thickness gauge, for example, as described in Japanese Patent Application Laid-open No. 54-21372, the tube to be detected is immersed in water and the tube to be detected is welded. An ultrasonic probe is placed at a position facing the bead, and the thickness is detected using a thickness meter.The ultrasonic probe is periodically scanned in the circumferential direction of the tube, and this scanning state is measured using a position detector. A variable afterimage time display device is configured to detect the inner surface of the tube, and displays the signal values of both the ultrasonic scanning position signal from the position detector and the tube thickness signal from the detected tube thickness gauge in XY. An apparatus has been proposed that measures the thickness distribution near the bead portion of the pipe, that is, the cut shape of the bead on the inner surface of the tube.

In addition, in Japanese Patent Application Laid-Open No. 56-3057, an ultrasonic probe is arranged around the outer periphery of the tube to be detected, the signal is output to an ultrasonic thickness gauge, and the ultrasonic probe is attached to the estimated seam area. A method has also been proposed in which the center of amplitude is moved periodically in the pipe circumferential direction and the inner shape of the welded part of the electric resistance welded pipe is determined by using the trajectory of the thickness output by the thickness gauge 5.

[Problem to be solved by the invention]

However, in the conventional method described above, an ultrasonic thickness gauge is attached to the outer periphery and one ultrasonic probe is scanned in the circumferential direction of the tube, thereby recognizing the shape of the bead on the inner surface of the tube. There was a problem.

(1) There is a limit to increasing the horizontal scanning speed of the ultrasonic probe compared to the traveling speed of the tube to be detected due to poor coupling of ultrasonic waves that occurs as the speed increases. . Therefore, the left and right scanning of the ultrasonic probe must be done at a speed that does not cause coupling failure, so the scanning of the ultrasonic probe runs diagonally relative to the tube to be detected. , many unmeasured parts that are not on the scanning line occur.

(2) Related to (1) above, since the measured cross section is oblique to the bead line, it does not accurately reflect the bead shape.

Due to the above-mentioned problems, it is not possible to accurately manage the bead shape online on the production line of electric resistance welded pipes.

Therefore, the main purpose of the present invention is to provide a tube inner bead cutting abnormality monitoring device that can easily and accurately measure abnormalities in the cutting shape of the bead portion of an ERW tube online to stabilize quality. .

[Means to solve the problem]

The above problem was solved by welding the butt part along the tube axis direction,
A device for monitoring the cutting state of the inner surface of a weld bead portion of an electric resistance welded pipe after the inner and outer surfaces of the welded portion have been cut, the device comprising: a frame that automatically traces the welded portion relatively in the pipe axis direction;
Ultrasonic probes attached to the frame for at least the center portion in the width direction of the bead portion and the base material portion, and an ultrasonic thickness sensor for obtaining wall thickness values based on signals from these ultrasonic probes. This problem was solved by equipping a meter and a calculation device that calculates the difference between the wall thickness values obtained from both ultrasonic thickness gauges and determines that the inner bead is abnormal if this difference value is outside the abnormality determination difference reference value. can.

[For production]

The present invention includes a frame that automatically traces a welded portion relatively in the tube axis direction, an ultrasonic probe attached to the frame for at least the center portion in the width direction of the bead portion and the base metal portion, and Since an ultrasonic thickness gauge is installed to obtain the wall thickness value based on the signal from the sonic probe, the thickness signal at the bead center can be obtained from the bead center ultrasonic probe. On the other hand, a thickness signal of the base material can be obtained from the base material ultrasonic probe.

In addition, whether the weld bead is abnormal due to cutting abnormality or not,
Because it is determined by the relationship between the thickness of the bead and the thickness of the base material,
If only one ultrasonic probe is used at a position looking at the weld bead, even if the change in thickness of the weld bead along the tube axis direction can be detected, it cannot be compared with the thickness of the base metal. Since cutting abnormalities cannot be detected, it is preferable to use two or more ultrasonic probes, and the greater the number of ultrasonic probes, the more accurate the determination becomes possible. According to the present invention, by installing at least two ultrasonic probes as described above and calculating the difference value between the signals from each ultrasonic probe, it is possible to reliably detect cutting abnormalities in the inner surface beat.

That is, while the thickness value of the base material part is constant under certain management, if there is a cutting abnormality in the bead part, the thickness value changes in the tube axis direction, so the above-mentioned difference value also changes. By continuously managing this difference value, it is possible to detect abnormally cut parts of the bead part online at an early stage.

[Specific structure of the invention]

The present invention will be explained in more detail below with reference to the drawings.

1 and 2 show an example of the device of the present invention.
1 is an electric resistance welded tube which is a tube to be detected, and 11 indicates a weld bead portion after cutting the inner and outer surfaces. 2 is ultrasonic probe 3A, 3B, 3C
It is a frame for mounting the servo controller 21, and is connected to a servo controller 21 for moving this in the tube circumferential direction and a motor 22, which is a driving part of the servo controller 21.
1 receives a signal from a known seam copying device 23 (not shown) and places an ultrasonic probe 3B at the center of the bead portion 11, an ultrasonic probe 3C at the edge of the bead portion, and an ultrasonic probe 3A.
The copying signal is sent to the motor 22 so that the
give against.

At least two ultrasonic probes 3A, 3B, and 3C, one for the bead center 3B and one for the base material 3A, are sufficient, but in this example, the ultrasonic probe 3C for the bead edge is used.
It is also provided. Of course, it is also possible to install four or more probes by adding probes to the bead portion and/or to the base material portion.

In this case, as will be described later, if a plurality of probes are provided in the bead portion or the base material portion, the average value at each portion can be used as the thickness signal for that portion.

On the other hand, each ultrasonic probe 3A, 3B, 3C is connected to a corresponding ultrasonic thickness gauge 5A, 5B, 5C,
Thickness can be measured based on the output signal from the ultrasonic probe. Furthermore, the signals of the thickness gauges 5A and 5B are both given to the first computing unit 6A, and the signals of the thickness gauges 5A and 5B are
Both signals are sent to the second arithmetic unit 6B. This computing unit 6A.

6B is designed to calculate the deviation of the thickness signals from both thickness gauges 5A and 5B, and the signals from the calculators 6A and 6B are set to predetermined deviation values in comparison setting devices 7A and 7B, respectively. If a certain allowable set value is exceeded, an alarm 8 will sound or an external display will be displayed.

Next, a method for monitoring the cut shape of a welded part using such a device will be described.

As mentioned above, as shown in FIG. 3, while the ERW tube 1 is moving in the direction of the arrow, the controller 21 causes the ultrasonic probes 3A, 3B, and 3C to follow the bead at a predetermined position and make contact. The thickness is detected via a medium such as a water column 4.4. During this process, for example, if there is an abnormal point (x mark) in the thickness at the center of the weld line, only the thickness value from the ultrasonic probe 3B changes as shown in Figure 4 (in Figure 4). ,(A)
, (B) and (C) are ultrasound probes 3A, 3B, respectively.
FIG. 3C is a graph showing thickness values from 3C versus time.

On the other hand, since the ultrasonic probe 3A always looks at the base material, its value is always constant.

Therefore, as shown in FIG. 2, the calculator 6A calculates the difference between the thickness value a from the ultrasound probe 3A and the thickness value from the ultrasound probe 3B, and calculates the absolute value of the difference Z=la -bl
, and the absolute value Z'=a-cl of the difference between the thickness value a and the thickness value C from the ultrasonic probe 3C, and the absolute value 2 or Z' is determined by the comparison setter 7A, 7B. When the standard deviation value is exceeded, it is determined that there is a cutting abnormality, and the location of the cutting abnormality is displayed by an appropriate warning device 8 such as an alarm.

As the ultrasonic flaw detection method in this specific example, a water column pulse reflection method can be used, but other methods such as a water immersion method and a jet pulse reflection method can also be used.

In addition, the device of the present invention transports the ERW tube in its axial direction, whereas the abnormality monitoring device is basically fixed in the axial direction, but conversely, the abnormality monitoring device is moved in the axial direction. You can also do that.

〔Effect of the invention〕

As mentioned above, in the conventional device, the continuous cross-sectional shape of the bead portion is measured and bead abnormality is determined based on this, which results in the occurrence of undetected portions, whereas in the present invention, Since the thickness of the bead part is continuously detected along its longitudinal direction, cutting abnormalities in the bead part can be reliably detected without the occurrence of undetected parts, reducing recycling costs and stabilizing quality. be able to.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic diagrams showing an example of the device of the present invention, FIG. 3 is a schematic diagram showing a state in which bead abnormality occurs, and FIG.
The figure is a graph corresponding to FIG. 3 showing the thickness values of each ultrasonic probe when an abnormality occurs. DESCRIPTION OF SYMBOLS 1... ERW pipe (detected pipe), 11... Weld bead part, 2-... Automatic copying frame, 21-... Servo controller, 22... Motor, 23... Seam copying device, 3A13B. 3C...Ultrasonic probe, 4-Water column, 5...Ultrasonic thickness gauge, 6A, 6B...Calculator, 7A, 7B--Comparison setting device, 8...Alarm. Figure Figure Figure Figure Figure (H") (H")

Claims (1)

[Claims] (1) A device that monitors the cutting condition of the inner surface of the weld bead portion of an ERW pipe after the butt portion along the pipe axis direction is welded and the inner and outer surfaces of the welded portion are cut, and the welded portion is connected to the pipe axis. A frame that automatically follows the direction relatively;
Ultrasonic probes attached to the frame for at least the center portion in the width direction of the bead portion and the base material portion, and an ultrasonic thickness sensor for obtaining wall thickness values based on signals from these ultrasonic probes. and an arithmetic device that calculates the difference between the wall thickness values obtained from both ultrasonic thickness gauges and determines that the inner bead portion is abnormal when the difference value is outside the abnormality determination difference reference value. This is a tube inner bead cutting abnormality monitoring device.