JPH0789046B2 - Method and device for detecting seam position of ERW pipe - Google Patents

Description

The present invention relates to a welding seam position detection method and device for an electric resistance welded pipe,
In particular, the present invention relates to a seam position detection method and device for an electric resistance welded pipe using a two-dimensional type light receiving device for performing optical position detection.

[Prior Art] FIG. 5 is an explanatory view showing a method for detecting the position of an outer surface welded portion of a conventional electric resistance welded pipe disclosed in, for example, Japanese Patent Laid-Open No. 61-250503. 8 is a seam portion of the electric resistance welded pipe 7,
Reference numeral 11-1 is a first strobe light emitting device, 11-2 is a second strobe light emitting device, and 12 is a linear camera. Further, FIG. 1A is a sectional view showing the positional relationship among the electric resistance welded pipe 7, its seam portion 8, the first and second strobe light emitting devices 11-1 and 11-2, and the linear camera 12, and FIG. ) Is a plan view showing the positional relationship between the irradiation parts A and B of the first and second strobe generators 11-1 and 11-2 and the light-receiving field C of the linear camera 12, and FIG. FIG. 6 is an explanatory diagram showing the positional relationship in the tube circumferential direction with the brightness detection signals D, E, F on the tube surface.

The operation of FIG. 5 will be described. The first and second strobe light emitting devices 11-1 and 11 are provided on the left and right above the electric resistance welded tube 7 which is moving horizontally.
-2 is arranged, and the seam portion 8 of the electric resistance welded pipe 7 and the surface in the vicinity thereof are slanted from the upper left and the upper right from the first and second sides.
The stroboscopic light emitting devices 11-1 and 11-2 are alternately made to emit light for irradiation. The first and second strobe light emitting devices 11-1 and
The linear camera 12 arranged between 11-2 measures the brightness of the surface by scanning and reading the second floor at the time of A part irradiation and B part irradiation shown in FIG. The luminance thus measured is usually the surface luminance signal D at the time of irradiation of the first strobe light emitting device 11-1 shown by the solid line in FIG. 7C and the second strobe light emitting device 11 shown by the broken line. The surface luminance signal E at the time of irradiation of -2 is obtained, and the signal position of F, which is the overlapping portion of both luminance signals, is detected as the seam position.

[Problems to be Solved by the Invention] In the conventional seam position detecting method and device for electric resistance welded pipe as described above, since two strobe devices are required, the strobe device is expensive and heavy. was there. Further, if two ordinary light projectors are used instead of the strobe device and arranged so that the irradiation positions do not overlap each other, then two linear cameras are required this time, which again causes a problem that the device is large and expensive.

The present invention has been made to solve the above problems, and provides a seam position detecting method and device for an electric resistance welded pipe which does not use the strobe device and can be realized by a single light receiving camera. With the goal.

[Means for Solving the Problems] In the seam position detecting method for an electric resistance welded pipe according to the present invention, the first and second light projecting devices are arranged above and below the electric resistance welded pipe that is moving horizontally, Irradiate the seam portion of the sewing tube and the surface in the vicinity thereof with individual irradiation ranges from diagonally upper left and upper right, and each irradiation range is irradiated only by its own light projecting device and includes the seam position therein. To do. By using a two-dimensional light receiving device as a light receiving device, the brightness signals obtained from the individual irradiation ranges are separately processed, and different seam positions are obtained from the respective brightness signals, so that the seam positions of both are the same. This is the only way to make that position a true seam position.

A method of using a television camera as the light receiving device and obtaining a seam position from a luminance signal of an individual irradiation range is as follows. In the arrangement of the light projecting range and the light receiving device so that the other of the irradiation range exists, the plurality of scanning lines existing in the irradiation range of the upper and lower visual fields,
The sum of the video signals for the specified screen is calculated individually for each pixel having the same horizontal address, and the portion where the individual sum exceeds the specified value is the brightness of the field of view corresponding to each irradiation part. The seam position detection method of the electric resistance welded pipes, which is the seam position signals obtained from the signals.

In the seam position detecting device for an electric resistance welded pipe according to the present invention, the seam part of the electric resistance welded pipe that is moving horizontally is sandwiched, and the irradiation surface including the seam part is obliquely irradiated by only its own light projecting device. Two light projecting devices provided so as to be formed on the surface of the electric resistance welded pipe, a first irradiation part which is illuminated only by the first light projecting device and includes a seam position therein, and a second light projecting device. A television camera provided in the middle of the two light projecting devices so as to include a second illuminated portion which is illuminated only by and includes a seam position in the vertical direction of its field of view; Detecting means for detecting the horizontal position and the vertical position of the video signal and the video signal at a predetermined arbitrary vertical position among the video signals respectively corresponding to the first irradiation portion and the second irradiation portion. For each pixel address of First summing screen defined because
An adding means and a second adding means; a first seam position detecting means and a second seam position detecting means for detecting a pixel address where the added value of the first adding means and the second adding means exceeds a specified value, respectively. It is provided with a third seam position detecting means for making a seam position the pixel address detected by both the first seam position detecting means and the second seam position detecting means.

[Operation] According to the seam position detecting method and device of the electric resistance welded pipe of the present invention, the irradiation ranges of the first and second light projecting devices are respectively illuminated only by their own light projecting devices, and the seam position is set therein. , And the two-dimensional light receiving device includes the individual irradiation range in its light-receiving field of view, so that the brightness signals obtained from the individual irradiation range are individually processed to detect individual seam positions. Then, the position where the seam positions of the two coincide with each other is detected as the true seam position.

Further, a television camera is used as the light receiving device, and the position is determined so that one irradiation range is present in the upper part and the other irradiation range is present in the lower part, which is obtained by vertically dividing the light receiving field of the television camera into two parts. For a plurality of scanning lines existing in the irradiation range of, the sum of the video signals for the specified screen is calculated individually for each of the pixels having the same horizontal address, and the individual sum exceeds the specified value. Are used as the respective seam position signals, and the position where the seam positions of the two coincide is detected as the true seam position.

As for the illumination brightness of the first and second light projecting devices, the scanning video signals are integrated for each horizontal scanning position for a plurality of scanning lines existing in the irradiation areas of the upper and lower parts, and the integrated value is binarized. The brightness control is automatically performed according to the number of seam position signals obtained as a result, so that a predetermined number of seam position signals are obtained.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of a seam position detecting method and device for an electric resistance welded pipe according to the present invention. 1-1 is a first light projecting device and 1-2 is a second light projecting device. Device, 2 is TV camera, 3
-1 is first adding means, 3-2 is second adding means, 4-1 is first seam detecting means, 4-2 is second seam detecting means, 5
Is a third seam detecting means, 6 is a synchronous detecting means, 7 is an electric resistance welded pipe, and 8 is a seam portion of the electric resistance welded pipe 7.

FIG. 2 is an explanatory diagram showing a light projecting device, its irradiation unit, a light receiving device, and a light receiving field. FIG. 1A is a sectional view showing the positional relationship among the electric resistance welded pipe 7, its seam portion 8, the first and second light projecting devices 1-1 and 1-2, and the television camera 2.
FIG. 2B is a plan view showing the positional relationship between the irradiation portions A and B of the first and second light projectors 1-1 and 1-2 and the light-receiving visual field C of the television camera 2, and FIG. FIG. 6 is a plan view showing the positional relationship between the respective positions of the irradiation portions A and B and the light receiving visual field C of FIG. 3B and the detection scanning line D of the A portion and the detection scanning line E of the B portion.

FIG. 3 is a waveform diagram for explaining the operation of FIG.

FIG. 4 is a partial detailed block diagram of FIG.

The operation of FIG. 1 will be described with reference to FIGS. As shown in FIG. 2 (a), the electric resistance welded pipe 7 is moving horizontally.
To the left and right above the seam portion 8 of the first and second light projecting devices 1
-1 and 1-2 are arranged, and the two light projecting devices irradiate the seam portion 8 and the tube surface in the vicinity thereof from an oblique direction. The irradiation ranges A and B on the surface of the electric resistance welded pipe by the two light projecting devices 1-1 and 1-2 respectively include a seam position 8 therein, as shown in FIG. 2 (b). It is an individual area that is illuminated only by its own projector, and the illumination range A, B is set by the TV camera 2.
In the case of receiving light, the upper half portion obtained by dividing the field of view of the television camera 2 into two in the vertical direction includes one irradiation range (A in the figure), and the lower half divided into two parts has the other irradiation range ( In the figure, B) is included, and one irradiation range (A in the figure) is located at a position slightly to the right with respect to the central axis of the visual field that bisects the visual field portion of the television camera 2 in the horizontal direction. The other irradiation range (B in the figure) is set at a position slightly on the left side. A brightness AGC (automatic gain control) control signal for automatically adjusting the irradiation brightness of the first and second light projecting devices 1-1 and 1-2 is respectively the first and second seam detecting means 4-. Input from 1 and 4-2. By the input brightness AGC control signal, the first and second light projecting devices 1-1 and 1-2 individually control the voltage supplied to their own light sources to adjust the brightness. As a result, the first and second seam position detecting means 4-1 are provided even if the power supply voltage fluctuates or the light projecting devices 1-1 and 1-2 change with time.
And 4-2, a predetermined number of detection position signals can be obtained and stable operation can be performed. FIG. 2 (c) shows the irradiation portion A of the first light projecting device 1-1 at a position slightly to the right of the upper half of the light receiving field C of the television camera 2, and a position slightly to the left of the lower half of the light receiving field C. Indicates that the irradiation portion B of the second light projecting device 1-2 is included at the same time. Further, a plurality of detection scanning lines D for detecting the seam portion in the A portion are provided in the irradiated portion of the A portion.
A plurality of detection scanning lines E for detecting the seam portion in the B portion are shown in the irradiation portion of the B portion. This is because if the TV camera 2 is a normal NTSC system, there are 262.5 even and odd field scanning lines, and 243.5 lines excluding the retrace line section.
For example, the four scanning lines from the 60th to the 63rd are the detection scanning lines D of the A section, and the four scanning lines from the 180th to the 183rd are the detection scanning lines E of the B section. A plurality of numbered scanning lines can be set as the detection scanning lines D and E of the A section and the B section, respectively. In this way, the first and second light projecting devices 1-1 and 1-2 are simultaneously turned on to irradiate the tube surfaces A and B of the electric resistance welded tube 7 including the seam section 8, and the irradiated A Section 2 and section B are simultaneously received by the TV camera 2 and the received video signal is scanned to output a composite signal (composite signal composed of a video signal and a synchronization signal).
Input to the synchronization detection means 6.

FIG. 4 shows the synchronization detecting means 6 and the first and second adding means 3-1.
And 3-2 is a block diagram showing an example. In FIG. 4, the sync detecting means 6 includes, for example, a video / sync signal separation circuit 61, a horizontal position counter 62, a vertical position counter 63,
And the A / B section scanning gate signal generation circuit 64. The first adder circuit 3-1 can be composed of, for example, a gate circuit 31-1, an AD converter 32-1, an adder 33-1, a storage circuit 34-1, and a selection circuit 35-1. The second adder circuit 3-2 may have the same configuration as the first adder circuit 3-1. Now, the composite signal from the TV camera 2 is video /
When input to the sync signal separation circuit 61, the circuit separates the video signal and the sync signal, and the video signal is included in the first and second adding means 3-1 and 3-2.
And 31-2, and the synchronization signal is supplied to the horizontal position counter 62 and the vertical position counter 63 as a horizontal clock signal and a vertical clock signal, respectively. As the vertical clock signal, for example, a signal of NTSC horizontal scanning frequency of 15.75 KHz is used, and as the horizontal clock signal, when the number of horizontal pixels of one scanning line is N, a signal of frequency 15.75 × N KHz is used. . The count value of the horizontal position counter 62 is stored in the storage circuit 34 as a horizontal position (horizontal axis direction) signal during scanning.
-1 and 34-2. The count value of the vertical counter 63 is input to the A / B scan gate signal generation circuit 64. The circuit 64 discriminates the input vertical position (position in the vertical axis direction) signal at the time of scanning and selects the A section scanning gate signal, that is, the four detection scanning lines D from the 60th to the 63rd in the previous example. The gate signal is supplied to the gate circuit 31-1 and the selection circuit 35-1.
In addition, the scanning gate signal of the B section, from the 180th to 183th in the previous example.
A gate signal for selecting the four detection scanning lines E up to the second is supplied to the gate circuit 31-2 and the selection circuit 35-2. First
In the adding means 3-1, the gate circuit 31-1 adds the video signal supplied from the video / synchronization signal separation circuit 61 and A
By the A section scan gate signal supplied from the section / B section scan gate signal generation circuit 64, only the video signals at the time of the four detection scans of the 60th to 63rd lines of the preceding example are allowed to pass through and the AD converter 32-
Output to 1. The AD converter 32-1 converts the input video signal into a digital value having a predetermined number of bits (for example, 4 to 8 bits) and supplies the digital value to one input of the adder 33-1. The selection circuit 35-1 uses the input A section scanning gate signal as a control signal, and when the video signal of the first (60th in the previous example) scanning line is input to the adder 33-1, it is input. The selected data "0" is output and supplied to the other input of the adder 33-1. Also from the second time (61st and later in the previous example)
When the video signal of the scanning line is input to the adder 33-1, the data of the corresponding horizontal position read from the storage circuit 34-1 is selectively output and supplied to the other input of the adder 33-1. . As a result, the video signal value of the first (60th in the previous example) scanning line is the same value as the output of the adder 33-1 and the video signal is integrated for each horizontal position during the second and subsequent scanning. The value is calculated and stored in the memory circuit 34-1. Therefore, when the 63rd detection scan of the preceding example is completed, the 60th to 63rd scan video signals are integrated for each horizontal position and stored in the storage circuit 34-1. Exactly the same as the second adding means 3-
Since 2 also operates, the 180th to 183rd scanning video signals are integrated for each horizontal position and stored in the storage circuit 34-2 when the 183rd detection scanning in the preceding example is completed. FIG. 3A shows the output signal obtained by the first adding means 3-1 from the irradiation portion A of the first light projecting device 1-1 in this way, and is supplied to the first seam detecting means 4-1. It In the same figure, (a) is an output signal similarly obtained by the second adding means 3-2 from the irradiation portion B of the second light projecting device 1-2, and is supplied to the second seam detecting means 4-2. The first and second seam detection means 4-1 and 4-2 include a seam detection section and an irradiation brightness control section. The seam detection unit is composed of, for example, a digital comparator and a reference data setting unit, and the scanning video integrated values of the A and B parts respectively inputted,
An output of 1 is output when the former value is larger than the latter value, and 0 is output in the opposite case by comparing with a preset reference data value.
Produces the output of. Therefore, a binarized output signal is obtained. This binarized first is shown in Fig. 3 (c) and (d).
And the output signals of the second seam detection means 4-1 and 4-2 are shown. Also, the first and second seam detecting means 4-1.
In order to stabilize the binarizing operation, the control unit 4-2 and the control unit 4-2 can each have a built-in irradiation brightness control unit that automatically adjusts the irradiation brightness of the first and second projectors. The function of the illumination brightness control unit is to generate a brightness AGC control signal. That is, when the number of horizontal position data detected by binarizing the scanning video integration signals of the respective A and B parts inputted is smaller than a predetermined number, the projection brightness is increased in order to increase the irradiation brightness of the corresponding projector. Increase the light source voltage of the optical device,
On the contrary, when the number of detected horizontal position data is larger than a predetermined number, a brightness AGC control signal for decreasing the light source voltage of the light projecting device is generated in order to decrease the irradiation brightness of the corresponding light projecting device. The irradiation brightness control unit can be configured by, for example, a subtractor that calculates a difference between two data values and a DA converter that converts an output value of the subtractor into a voltage signal. In general, the brightness of the light projecting device varies depending on the power supply voltage, and the brightness also decreases over time. Therefore, the brightness AGC function is practically effective for the device. The first and second seam detecting means 4-1 and 4-2 respectively supply output signals to the third seam detecting means 5. The third seam detecting means 5 is the first
And a circuit for calculating a logical product of the binary scanning video signals respectively input from the second detecting means 4-1 and 4-2 for each horizontal position and generating an output only when both signals are present. Is. Therefore, the third seam detecting means can be configured by an AND circuit. In this way, among the binarized scanning video signals detected from the irradiation portions A and B of the first and second light projecting devices 1-1 and 1-2, respectively, the signals existing at the same horizontal position of the scanning line are The seam position detection signal is output from the third detecting means 5, and this output signal is the seam position detection signal having the waveform shown in FIG.

EFFECTS OF THE INVENTION Since the present invention is configured as described above,
The following effects are achieved.

The irradiation range of each of the first and second light projecting devices is an individual irradiation range that is illuminated only by its own projecting device and includes a seam position therein, and two-dimensional light reception such as a television camera. By receiving the individual irradiation areas at the same time by the device, detecting individual seam position signals from the scanning video signals existing in each irradiation area, and detecting the position where both seam positions match as the true seam position. The seam position of the electric resistance welded pipe can now be detected with one light-receiving camera without using the two strobe devices that were required in the past.

Also, by using a CCD camera as the light receiving device, it has become possible to reduce the size and weight of the device. Therefore, when the quality of the welded portion of the electric resistance welded pipe is inspected by the ultrasonic flaw detector, it is possible to house the pair of the projector and the CCD camera of the present invention in the probe holder of the ultrasonic flaw detector. became.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a seam position detecting method and device for an electric resistance welded pipe according to the present invention, and FIG. 2 is an explanatory view showing a light projecting device, its irradiation part, a light receiving device, and a light receiving visual field. FIG. 4 is a waveform diagram for explaining the operation of FIG. 1, FIG. 4 is a partial detailed block diagram of FIG. 1, and FIG. 5 is an explanatory diagram showing a position detection method of an outer surface welded portion of a conventional electric resistance welded pipe. Is. In the figure, 1-1 is a first light projecting device, 1-2 is a second light projecting device, 2 is a television camera, 3-1 is a first adding means, and 3-.
2 is the second adding means, 4-1 is the first seam position detecting means,
4-2 is a second seam detecting means, 5 is a third seam detecting means, 6 is a synchronous detecting means, 7 is an electric resistance welded pipe, 8 is a seam portion, 11
-1 is a first strobe light emitting device, 11-2 is a second strobe light emitting device, 12 is a linear camera, 13-1, 13-2 are gate circuits, 32-1, 32-2 are AD converters, 33-1 , 33-2 is an adder,
34-1, 34-2 are memory circuits, 35-1, 35-2 are selection circuits, 61
Is a video / sync signal separation circuit, 62 is a horizontal position counter,
Reference numeral 63 is a vertical position counter, and 64 is an A / B scan gate signal generation circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiro Wada 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (56) Reference JP-A-61-250503 (JP, A) JP-A-SHO 62-192603 (JP, A) JP-A-61-230005 (JP, A)

Claims (3)

[Claims] 1. A light projecting device is provided by sandwiching a seam portion of an electric resistance welded tube which is moving horizontally, and the two light projecting devices are used to obliquely light the surface of the electric resistance welded pipe including the seam portion. And the brightness of the surface is measured by a light receiving device disposed between the two light projecting devices, and the seam position is detected based on the brightness measurement signal. The projection range on the surface of the electric resistance welded tube of
There is a first illuminated portion illuminated by only the first floodlight and having a seam position therein, and a second illuminated portion illuminated only by the second floodlight and having a seam position therein. And a two-dimensional light receiving device is used as the light receiving device.
The luminance signal from the visual field portion corresponding to the illuminated portion and the second signal
The luminance signal from the field of view corresponding to the illuminated portion is processed separately to obtain the seam position signal separately from each luminance signal, and only when both seam position signals match, that position is regarded as the true seam position. A seam position detection method for an electric resistance welded pipe, comprising: 2. A method of using a television camera as the light receiving device and obtaining seam positions from luminance signals from a visual field portion corresponding to a first irradiation portion and a visual field portion corresponding to a second irradiation portion, respectively. The first half of the vertical
The arrangement of the light projecting range and the light receiving device is determined such that the first irradiation portion is present in the portion of 1 and the second irradiation portion is present in the other portion, and one or more scanning lines present in the first portion are defined. ,
A seam position in which a sum of video signals for a specified screen is calculated for each pixel having the same horizontal address, and a portion where the sum exceeds the specified value is obtained from the luminance signal of the visual field portion corresponding to the first irradiation portion. As a signal, for one or more scanning lines present in the second portion,
A seam obtained by calculating the sum of the video signals for the specified screen for each pixel having the same horizontal address, and obtaining the part where the sum exceeds the specified value from the luminance signal of the visual field part corresponding to the second irradiation part. The method of detecting a seam position of an electric resistance welded pipe according to claim 1, which is a method of using a position signal. 3. A seam portion of an electric resistance welded tube which is moving horizontally, and an irradiation surface including a seam portion which is obliquely irradiated by only its own light projecting device is formed on the surface of the electric resistance welded tube. The two projection devices provided on the first projection part and the first projection part which is illuminated only by the first projection device and which includes the seam position therein, and the second projection device which is illuminated only by the second projection device. A television camera provided in the middle of the two light projecting devices so as to include a second irradiation portion included therein in a vertical direction of its field of view, and a horizontal position and a vertical position of a video signal from the television camera. A synchronization detecting means for detecting a position, and a video signal corresponding to a predetermined arbitrary vertical position among video signals corresponding to the first irradiation portion, for adding a predetermined screen for each pixel address in the horizontal direction. Adding means,
First seam position detecting means for detecting a pixel address where the added value of the first adding means exceeds a prescribed value; and a video signal at a predetermined arbitrary vertical position among the video signals corresponding to the second irradiation portion. Second addition means for adding a predetermined screen amount for each pixel address in the horizontal direction,
Second seam position detecting means for detecting a pixel address for which the added value of the second adding means exceeds a prescribed value, and seam pixel addresses detected by both the first seam position detecting means and the second seam position detecting means. A seam position detecting device for an electric resistance welded pipe, which has a third seam position detecting means for positioning.