JPH03158706A - Detecting device for seam position of welded pipe - Google Patents

Abstract

PURPOSE:To improve the quality and guarantee performance by varying and setting the horizontal position of a light source in the section of the seam welded pipe and the axial angle and circumferential angle of the seam welded pipe adaptively to the size of the seam welded pipe. CONSTITUTION:Data on the size of the seam welded pipe 20 which is manufactured is passed through a console panel 14 and a computing element 5 to select data on the best position in a table of positions (X, phi, theta) in correlation with the seam welded pipe 20 which are obtained by a preliminary test. The data on the best horizontal position (X) is sent to a horizontal movement controller 9 and a motor 10 for horizontal movement is driven and controlled to move light source bodies 1 and 2 to set positions. Then data on the best axial angle (phi) is sent to an axial angle controller 7 and a motor 11 for axial angle variation is controlled to set the axial angles of the light source bodies 1 and 2 to the best angles. Then data on the best circumferential angle (theta) is used to set the circumferential angles of the light source bodies 1 and 2 to the best angles through circumferential angle controllers 6 and 8 and circumferential angle varying motors 12 and 13, thereby detecting the seam of the seam welded pipe 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a seam position detection device in the circumferential direction of a steel pipe in an electric resistance welded pipe manufacturing line.

[Conventional technology]

Normally, ERW steel pipes are manufactured by continuously forming a steel strip into a cylindrical shape using a group of forming rolls, and then joining the joints using electric resistance welding. As shown in Figure 7, position measurement has traditionally been carried out by
The method used is to detect the reflection intensity around the seam using an image sensor or the like while irradiating the seam with a light source, and to use a method based on this reflection intensity distribution.

That is, the light source 3 is located symmetrically above the electric resistance welded tube 35.
The cameras 3 and 4 located directly above the electric resistance welding tube 35 detect the difference in the reflected light intensity distribution 36 between the seam part 33 and the base material part 32 using the light beam irradiated from 0.31, and further detect the reflected light intensity distribution. 36 waveforms are binarized (processing to divide the waveforms into bright and dark by applying slicing processing)
After that, the seam position was detected by performing arithmetic processing.

Typical waveforms obtained by such a method are shown in (a) to (i) in FIG.

[Problem to be solved by the invention]

Among the waveforms shown in (a) to (i) in Fig. 8, (a) to
The waveform type (C) can be dealt with simply by adjusting the slice level during the binarization process. Also, (d)
The waveform types (e) can be dealt with by electrically amplifying the peak level without adjusting the slice level.

However, the abnormal waveforms shown in (f) to (i) cannot be dealt with by the processing performed for (a) to (e), resulting in the problem that the seam position cannot be detected. there were.

Therefore, the purpose of the present invention is to improve quality and guarantee performance by preventing the occurrence of abnormal waveforms as shown in (f) to (i) as much as possible, and thereby accurately grasping the seam position. An object of the present invention is to provide a seam position detecting device for an electric resistance welded pipe.

[Means to solve the problem]

The above-mentioned problem is provided with a camera disposed facing the electric resistance welded pipe and looking at the seam part thereof, and two floodlight sources located symmetrically on both sides of a line connecting the camera and the seam part. In a seam position detection device for an ERW tube that detects a seam position based on the reflection intensity distribution of a light beam irradiated from a light source to the ERW tube, the distance from the longitudinal section passing through the seam portion of the ERW tube to each of the light sources is determined. a rotational drive means for varying the axial direction angle of the electric resistance welded tube on a plane parallel to the longitudinal section passing through the light source; This can be solved by providing a rotary drive means for making the angle in the circumferential direction of the sewing tube variable.

[Effect]

In the conventional seam position detection device, the position and angle of the light source installed above the ERW tube are always fixed, so for example, the size of the ERW tube 35 is A-4B- as shown in FIG. +c, the waveform captured by the camera 34 gradually changes due to changes in the specularly reflected light and scattered reflected light due to changes in the reflected light intensity distribution on the base material surface, and finally the graph This causes a problem of abnormal waveforms as shown in GC.

Therefore, the present inventor focused on the fact that there is a quantitative correlation between the irradiation position of the light source and its angle, and the outer diameter and surface texture of the ERW tube. By making the axial angle and circumferential angle of the ERW tube variable and setting them to match the size of the ERW tube, it is possible to always obtain a good reflection intensity distribution waveform.

[Specific structure of the invention]

The present invention will be explained in detail based on embodiments with reference to the drawings of FIGS. 1 to 6.

FIG. 1 is a control block diagram for explaining the apparatus of the present invention.

A light source body 1.2 is installed above the electric resistance welded tube 20, which is an object to be detected, and is positioned symmetrically with respect to the vertical center line of the electric resistance welded tube 20. Further, above the electric resistance welded tube 20, a camera 3 is installed on the vertical center line of the electric resistance welded tube.

The mechanisms of the light source body 1.2 and camera 3 will be explained in more detail with reference to FIGS. 2(&) and (b).

The light source bodies 1 and 2 are attached to the front part of the light source system body 28, 29 and are integrally formed. The light source system 28.
The convex step grooves 28a and 28b provided on the upper and lower plates of 29 are fitted into the fitting grooves 25a and 25b provided on the upper and lower plates of the light source body storage box 25, respectively, as shown in FIG. 2(a). It is configured to slide in the horizontal direction of the page (hereinafter referred to as "horizontal direction"). The movement of the light source systems 28 and 29 is performed by a horizontal movement motor 10 disposed on the upper part of the light source body storage box 25. That is, the reversible ball screw 27 inserted into the longitudinal center of the light source body storage box 25 is threaded in the opposite direction from left to right with its center as a platform, and is further provided at the back of the light source body 28 and 29. The protrusions 28c and 29c are screwed together. The other end of the reversible ball screw 27 protrudes to the side of the light source body storage box 25, and is connected to the output shaft 1.0a of the horizontal movement motor 10 and the timing belt 2.
6, and the reversible ball screw 27 is rotated by the rotation of the output shaft 10a of the horizontal drive motor 10. Therefore, this reversible ball screw 2
7, the light source bases 28 and 29 slide symmetrically in the left and right directions by the same amount with respect to the center of the light source base storage box 25. In the case of this embodiment, this slideable amount lA, 111 is:
It is 150a+m.

On the other hand, the rotation of the light source 1.2 in the θ, θ, force direction (Fig. 3 (
c) Reference (hereinafter referred to as circumferential rotation) is the light source base 28
．． Circumferential angle variable motor 12 provided inside 29
．． 13. Said circumferential angle variable motor 1
2.13 output shafts 12a, 13a and light source bodies 1, 2, and a pivot 1b provided on the back surface of rotary plates 1a, 2a which are integrally fixed.

The rotating gears provided in 2b are in mesh,
Output shaft 12a of the circumferential angle variable motor 12.13
, 13a, the rotating plate 1a.

2a is rotated, and the light source body 1.2 fixed to the rotary plates 1a and 2a is rotatable in the circumferential direction of the electric resistance welded tube. In the case of this embodiment, this rotatable angle is
Both angles are set at 45°.

On the other hand, the rotation of the light source 1.2 in the ψ direction (FIG. 3(b), hereinafter referred to as axial rotation) is performed by the axial angle variable motor 11 provided inside the base 30. The protrusion 25c provided on the back of the light source body storage box 25 is connected to the pivot 3.
1, and the entire light source body storage box 25 rotates about this pivot 31 as a rotation center, and the disk 25e fixedly protruded from this protrusion 25C and the axial angle variable The output shaft 11a of the motor 11 is connected with a timing belt 32, and as the output shaft 11a of the axial angle variable motor 11 rotates, the light source 1.
2 rotates in the axial direction of the electric resistance welding tube so that the direction of light emission can be changed. This possible rotation angle range is 0° to 3
It is set to 0°.

The focal length of the camera 3 is automatically adjusted by drive motors 33, 34 provided on its side.

The main body of the light source device in this embodiment is constructed as described above, but the horizontal movement motor 10, the circumferential angle variable motor 12, 13, and the axial angle variable motor 11 each have their own respective motors. Encoders 16, 18, 19, 11 are attached to control the amount of motor rotation. Further, in order to control each of these motors, the horizontal movement motor 10 and encoder 16 are connected to the horizontal movement controller 9, and the circumferential angle variable motor 12.13 and encoder 18.19 are connected to the horizontal movement controller 9, respectively. The first circumferential angle controller 6 and the second circumferential angle controller 8 are connected, and the axial angle variable motor 1.1 and the encoder 17 are further connected to the axial angle controller 7. Each of these controllers 6.7.8.9
is connected to the computing unit 5 for centralized management.

On the other hand, camera 3 is connected to camera controller 4,
Furthermore, branch connections are made to a synchroscope and the arithmetic unit 5 for observing the reflected light intensity distribution or performing electrical processing.

The device of the present invention is constructed as described above, and when operating it, first, the optimum irradiation position of the light source 1.2 is determined in advance according to the size and surface texture of the electric resistance welded tube 20, which is the object to be detected. Since it is necessary to understand the relationship between the axial angle and the circumferential angle, tests are conducted for each size of the electric resistance welded tube 20. This test will be explained based on FIGS. 3 and 4.

First, in order to find the optimal horizontal position (X) of the light sources 1 and 2, as shown in FIG.
While being moved in the horizontal direction by the horizontal angle variable motor 10, the waveform of the reflected light intensity distribution is observed by the synchroscope 15, and the position where the waveform becomes a two-peak waveform is found. A correlation diagram obtained by performing this operation for each size of the electric resistance welded tube 20 is shown in FIG. 4(a).

Next, in order to find the optimal axial direction angle (ψ),
As shown in b), while the light source body 1.2 is irradiated in the axial direction of the electric resistance welded tube by the axial angle variable motor 11,
Similarly, the waveform of the reflected light intensity distribution is observed using the synchroscope 15, and the angle at which the double waveform level reaches its peak is found. A correlation diagram obtained by performing this operation for each size of the electric resistance welded tube 20 is shown in FIG. 4(b).

Similarly, in order to find the optimum circumferential angle (θ), as shown in FIG. Similarly, the waveform of the reflected light intensity distribution is observed using the synchroscope 15, and the angle at which the two-peak waveform is least affected by the surface texture or flaws is found. This operation is performed for each size of the ERW tube 20, and the obtained correlation diagram is shown in FIG. 4 (C).
FIG.

Figure 4 (a) (b) (
The correlation shown in c) is stored in the calculator 5, so that the horizontal position (X), axial angle (ψ), and circumferential angle (θ) that match the size of the ERW tube 20 can always be selected. Keep it.

In actual operation, data on the size of the 2° electric resistance welded pipe to be manufactured is inputted to the calculator 5 from the operation panel 14. The calculator 5 selects data on the optimum position from the table of correlation positions (X, ψ, θ) with the electric resistance welded pipe 20 obtained in the preliminary test. Data on this optimum horizontal position (X) is sent to the horizontal movement controller 9, which drives and controls the horizontal movement motor 0 to move the light sources 1 and 2 to the set positions. .

When this movement is completed, data on the optimum axial angle (ψ) is sent from the calculator 5 to the axial angle controller 7, and the axial angle controller 7 controls the axial angle variable motor 11. Drive controlled, light source body 1
, 2 are set as the optimum angles. When this operation is completed, data on the optimum circumferential angle (θ) is then sent from the calculator 5 to the first circumferential angle controller 6 and the second circumferential angle controller 8, respectively.
The first circumferential angle controller 6 and the second circumferential angle controller 8 drive and control the circumferential angle variable motors I2 and I3, and set the circumferential angles of the light sources 1 and 2 to optimal angles. After the above-described position setting and angle setting of the light source body 1.2 are completed, seam detection of the electric resistance welded tube 20 is sequentially performed.

Next, FIG. 5 shows the results of a test of abnormal waveform occurrence rate for each size of electric resistance welded pipe using the apparatus of the present invention.

Further, for comparison, FIG. 6 shows the results of a test of abnormal waveform occurrence rate using a conventional device.

In both FIG. 5 and FIG. 6, the vertical axis shows the abnormal waveform occurrence rate, and the horizontal axis shows the external dimensions of the electric resistance welded tube.

According to the test results, when the seam position was detected using the conventional device, the abnormal waveform occurrence rate was 38% on average, whereas when the seam position was detected using the device of the present invention, abnormal waveforms occurred. The rate could be reduced to an average of 2%.

〔Effect of the invention〕

As explained in detail above, according to the present invention, by adjusting the horizontal position, axial angle, and circumferential angle of the light source to optimal positions depending on the size of the ERW pipe, the occurrence of abnormal waveforms can be significantly reduced, and the seam It is possible to accurately grasp the location of parts, thereby improving quality and guarantee performance.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram for explaining the device of the present invention;
Figures 2 (a) and (b) are diagrams for explaining the mechanism of the light source device. (a) is a front view, (b) is a left side view, and Figure 3 (a)
(b) (c) are diagrams for explaining the horizontal position and angle setting of the light source, and Figures 4 (a), (b), and (e) are the horizontal position and angle setting of the light source and the size of the ERW pipe. Figure 5 is a diagram showing the results of a test of abnormal waveform occurrence rate for each size of ERW pipe using the device of the present invention, and Figure 6 is a diagram showing the results of a test of abnormal waveform occurrence rate using a conventional device. Figure 7 is a diagram for explaining the conventional seam position detection device, and Figures 8 (a) to (i) show typical waveforms obtained by the conventional seam position detection device. 9 are diagrams for explaining the occurrence of abnormal waveforms in the conventional device.・2...Light source, 3...Camera...Camera controller 5...Calculator ・8...
・Controller for circumferential angle...Controller for axial angle...Controller for horizontal movement 0...Motor for horizontal movement...Motor 2 and 13 for variable axial angle...For variable circumferential angle Motor 6/17/18
・19... Encoder 〇... ERW tube (α) (α) (α) Figure (b) Figure (b) (b) (C) Diameter angle IL20 (C) (α) (b) (C) Figure (d) (e) (f) (9) Mountain) Figure A

Claims (1)

[Claims] (1) A camera disposed facing the electric resistance welded pipe and gazing at the seam, and two projecting light sources located symmetrically on both sides of a line connecting the camera and the seam; In the seam position detection device for an ERW tube, which detects the seam position based on the reflection intensity distribution of light rays irradiated onto the ERW tube from a rotation drive means for varying the axial direction angle of the ERW tube on a plane parallel to the longitudinal section passing through the light source; 1. A seam position detection device for an electric resistance welded pipe, characterized by comprising: rotational drive means for varying the angle in the circumferential direction of the pipe.