JPH10170228A - Detecting device for seamed part of electro-resistance welded pipe and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electro-resistance welded pipe seamed part detecting device and its method which can carry out the most suitable and highly accurate detection of a seamed part to the surface state of an electro-resistance welded pipe. SOLUTION: An electro-resistance welded pipe seamed part detecting device 7 has a main face light source 23 which irradiates obliquely in the proceeding direction of an electro- resistance welded pipe P at the perpendicularly upward position of the axial center of the welded pipe P as an illumination section 15; auxiliary face light sources 24 which are located on both upper sides with the axial center of the welded pipe P located between them, and irradiate an area about the same as the irradiating area of the main face light source with an inclination set up so as to be rectangular to the axis of the welded pipe P and to severally include the axial position of the welded pipe P; and a point light source 25 which irradiates an area about the same as the irradiating areas of the main face light source 23 and of the auxiliary face light source 24 from the perpendicularly upward position of the axial center of the welded pipe P, and these light sources are changed over according to the surface state of the welded pipe P. In addition, the welded pipe seamed part detecting device 7 is equipped with a CCD camera, an image processing section 17 and a following mechanism 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric resistance welded pipe manufacturing line for detecting an electric resistance welded seam required for positioning a probe of an ultrasonic flaw detector in order to automate a seam inspection process and improve accuracy. The present invention relates to an apparatus and a method.

[0002]

2. Description of the Related Art In general, an electric resistance welded pipe is formed by passing a steel strip through a group of forming rolls and bending both side edges thereof into a cylindrical shape. Is heated and passed between squeeze rolls, and the two side edges are joined together by welding. After that, the weld bead formed at the welded portion (hereinafter referred to as seam portion) is cut and removed and passed through a group of sizer rolls to form Manufactured.

[0003] In the ERW pipe manufactured as described above, since defects are easily generated in the seam portion, the seam portion is subjected to ultrasonic flaw detection for quality control. Ultrasonic flaw detection is performed in a process from cutting a weld bead and cooling it in a cooling water tank to sending it to a group of sizers.
The seam portion is likely to shift in the circumferential direction due to the condition of the sizer roll at the time of exchanging the bead cutting tool or changing the forming roll for changing the material size. Therefore, when performing the ultrasonic flaw detection, it is necessary to accurately detect the position of the seam portion and make the probe of the ultrasonic flaw detection apparatus follow the detected seam portion.

[0004] As described above, the following method has conventionally been disclosed as a method for optically detecting the seam portion of the electric resistance welded tube when the seam portion is subjected to ultrasonic flaw detection. (1) Japanese Unexamined Patent Publication No. 1-302103 discloses that each of two light emitting devices provided with a seam portion of an electric resistance welded tube interposed between different positions on the surface of the electric resistance welded tube including the seam portion from an oblique direction. Light is irradiated, each irradiation position is simultaneously imaged by one television camera, and one or more scanning lines existing in each of two fields of view corresponding to each irradiation position are displayed on these scanning lines. The luminance signal is binarized separately to obtain two position signals indicating the one-dimensional position of the seam portion in the circumferential direction of the ERW tube. A method of detecting as a true seam position in a direction is disclosed.

(2) Japanese Patent Application Laid-Open No. 4-340403 discloses that a surface of an electric resistance welded tube is irradiated with light obliquely from above and the irradiated portion is two-dimensionally imaged. Detects the difference in brightness resulting from the difference in the hue of the peripheral surface, binarizes the seam portion into black and the rest into white, and processes the area of the seam portion in a window enclosing the necessary surface to be measured with a frame. A method of calculating the center of gravity based on (the number of pixels) and detecting a true seam position is described.

(3) In Japanese Utility Model Laid-Open No. 5-50312, an illuminometer is provided in order to clarify the difference in color between the seam portion and the peripheral surface in Japanese Patent Application Laid-Open No. 4-340403.
A method of preventing occurrence of an abnormal binarized image and grasping a seam position is described.

[0007]

However, (1)
In the seam portion position detection method disclosed in Japanese Patent Application Laid-Open No. 1-302103, although the light projection device adjusts the brightness, it also irradiates the ERW tubes having different surface treatments from the same position. For example, the surface is pickled, and the seam is heat-treated.
In addition, in the electric resistance welded pipe in which the seam portion is subjected to the heat treatment, the surface is blackish as a whole, and it is difficult to distinguish the seam portion from the periphery thereof, and it is difficult to detect the seam portion.

Further, the method disclosed in JP-A-1-302103 (1) has a disadvantage that the position detection accuracy is significantly reduced due to disturbance noise such as water droplets attached to the ERW pipe. Further, in the method of JP-A-1-302103 of (1), the signal processing of the imaging result of the television camera is complicated,
In addition, since the seam position detection result is obtained one-dimensionally, there is a problem that the measurement accuracy is poor. Also, in the method of JP-A-1-302103 of (1), the electric resistance welded tube is horizontally fast (about 100
m / min) as well as in the axial (circumferential) direction, it is difficult to match the seam images separately obtained by the left and right light projectors.

Further, the seam portion position detection method described in (2) Japanese Patent Application Laid-Open No. 4-340403 is a two-dimensional seam method for improving the problem of (1) Japanese Patent Application Laid-Open No. 1-302103. The center of gravity is obtained from the area measurement of the part, and the signal processing is simplified and the accuracy is improved. However, when the color difference between the seam part and its surroundings is small like the ERW pipe in the above example, Is unclear, the seam part may not be detected accurately because the binarization level for distinguishing the seam part from the surrounding area is constant.

In the seam portion position detection method described in (3) Japanese Utility Model Application Laid-Open No. 5-50312, an illuminometer is added to automatically optimize the binarization level (2). ) Of Japanese Patent Application Laid-Open No. 4-340403, the surface condition of the material is not only changed by the wall thickness, but also greatly changed by the surface treatment of the ERW pipe, the welding condition, and the like. Difficult to use for a wide variety of products.
Further, if the seam state after the bead cutting is poor, the area of the seam portion greatly changes, resulting in a large detection error.

As described above, the conventional seam position detection method for ultrasonic flaw detection is not widely applicable to all types of ERW pipes, and is difficult to detect depending on the surface condition of ERW pipes. Or the calculation process of the image processing is complicated and the seam portion cannot be detected efficiently.

An object of the present invention is to solve the above-mentioned problem, and it is possible to perform an optimum seam detection in accordance with the surface condition of an electric resistance welded tube and improve the accuracy of the seam detection. It is an object of the present invention to provide a tube seam detection device and method.

[0013]

In order to achieve the above object, according to the present invention, an illuminating means for irradiating the surface of an ERW pipe uses an optimum light source in accordance with the surface condition of the ERW pipe. I have. By doing so, an appropriate halation occurs in the seam portion and the irradiation area around the seam portion, and the seam portion is emphasized, so that the seam portion and the periphery thereof can be easily distinguished.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors conducted various experiments on the surface condition and lighting of an electric resistance welded tube. The experimental conditions were as follows: (1) pickling treatment, (2)
(3) pickling treatment and heat treatment applied to seam portion, (4) black skin covered and heat treatment applied to seam portion From the main surface light source provided vertically above the axis of the ERW pipe, irradiate it obliquely in the direction of travel of the ERW pipe, and from the auxiliary surface light sources provided on both sides of the ERW pipe at the upper position across the axis. Irradiation in a direction perpendicular to the axis of the ERW pipe, and tilted so as to include the axis position of the ERW pipe, irradiating substantially the same area with the main surface light source and the auxiliary surface light sources on both sides simultaneously, Immediately below a point light source provided at a position vertically above the axis, the seam portion was detected in that state. Table 1 shows the results.

[0015]

[Table 1]

As described above, the surface condition of the electric resistance welded tube is (1)
In the case of the one subjected to the pickling treatment, the main surface light source and the auxiliary surface light source, when irradiated by the seam portion and its surroundings are best distinguished, furthermore, the main surface light source, or the auxiliary surface light source,
When the irradiation was performed, the seam portion and the periphery thereof were distinguished well. When the surface state of the electric resistance welded tube is covered with black scale (2), the main surface light source and the auxiliary surface light source irradiate the seam portion and its surroundings best when irradiated by the main surface light source and the auxiliary surface light source. When illuminated with a light source, the seam portion and its surroundings were well distinguished. In addition, when the surface condition of the electric resistance welded tube is (3) one subjected to pickling treatment and heat treatment applied to the seam portion, and (4) one covered with black scale and subjected to heat treatment to the seam portion, Only by the method of irradiating with a point light source, the seam portion and the periphery thereof could be distinguished best. According to the above experiments, the present inventors have found that seam portions can be easily determined by detecting seam portions with illumination and arrangement suitable for surface treatment of the electric resistance welded tube, thereby improving the accuracy of seam portion detection. Was found.

That is, the first ERW seam detecting device according to the present invention is a device for detecting a seam portion of an ERW pipe whose surface is pickled, and irradiates the surface of the ERW pipe. Illuminating means, imaging means for imaging the position illuminated by the illuminating means, and image processing means for performing image processing on an image captured by the imaging means and detecting a seam portion. Irradiation is performed by using a main surface light source which is disposed at a position vertically above the axis of the ERW pipe and is obliquely inclined in the traveling direction of the ERW pipe.

The second ERW pipe seam detecting device according to the present invention is a device for detecting a seam portion of an ERW pipe whose surface is pickled or covered with black scale, 1 in place of the main surface light source of the ERW pipe seam detection device, it is located on both upper sides with respect to the axis of the ERW pipe, in a direction perpendicular to the axis of the ERW pipe,
In addition, auxiliary surface light sources are used which are arranged so as to be irradiated so as to include the axial position of the ERW tube.

Further, the third ERW pipe seam detecting device according to the present invention is the second ERW pipe seam detecting device,
In place of the auxiliary surface light source, a main surface light source that is disposed obliquely at a position vertically above the axis of the ERW tube so as to be inclined in the traveling direction of the ERW tube,
It is located on the upper both sides of the axis of the ERW pipe, in the direction perpendicular to the axis of the ERW pipe, and includes the axial position of each ERW pipe, and irradiates the same area as the main surface light source. An auxiliary surface light source that is arranged at an angle is used.

The fourth ERW pipe seam detecting device according to the present invention is characterized in that the surface is pickled and the seam is covered with a heat-treated ERW pipe or black scale, and the seam is provided. Is a device for detecting a seam portion of a heat-treated electric resistance welded tube, and irradiates from a position vertically above the axis of the electric resistance welded tube instead of the main surface light source of the first electric resistance welded seam portion detection device. A point light source is used.

Further, in the fifth electric resistance welded seam detecting device according to the present invention, the illuminating means of the first electric resistance welded seam detecting device may be such that the electric resistance welding is performed at a position vertically above the axis of the electric resistance welded tube. A main surface light source that is arranged obliquely in the direction of travel of the tube, and positioned on both upper sides of the electric resistance welded tube at the downstream side of the main surface light source so as to irradiate the same illumination range as the main surface light source. And an auxiliary surface light source for irradiating in a direction perpendicular to the axis of the ERW pipe, and tilting so as to include the axis position of the ERW pipe, and from the vertically upper position of the axis of the ERW pipe directly downward. It has a point light source that irradiates the same range as the irradiation range of the main surface light source and the auxiliary surface light source, and switching means for switching these light sources according to the surface state of the ERW tube.

In the above construction, the first electric resistance welded seam detecting device detects the seam of the electric resistance welded pipe whose surface has been pickled, and the main surface light source detects the seam of the electric resistance welded pipe. Irradiation is performed at a position obliquely oblique to the traveling direction of the electric resistance welded tube from a vertically upper position. By irradiating in this manner, halation is appropriately performed on portions other than the seam portion, and as a result, the seam portion is emphasized. Then, an image of the irradiated part is taken, and image processing is performed on the taken image data to detect a seam portion.

Further, the second ERW pipe seam detecting apparatus according to the present invention detects an ERW pipe whose surface is pickled and an ERW pipe whose surface is covered with black scale. sometimes,
The auxiliary surface light source emits light from above both sides of the axis of the ERW pipe in a direction perpendicular to the axis of the ERW pipe and inclined so as to include the axial position of the ERW pipe. By irradiating in this way,
The portions other than the seam are appropriately halationed, and as a result, the seam is emphasized. Then, an image of the irradiated part is taken, and image processing is performed on the taken image data to detect a seam portion.

Further, the third ERW pipe seam detecting device according to the present invention detects an ERW pipe whose surface is pickled and an ERW pipe whose surface is covered with black scale. sometimes,
The main surface light source emits light from a position vertically above the axis of the ERW tube obliquely in the traveling direction of the ERW tube, and the auxiliary surface light source emits ERW tubes from both sides above the ERW tube axis. The main surface light source and the auxiliary surface light source irradiate the same area at the same time in the direction perpendicular to the axis and at an angle to include the axial position of the ERW tube. As a result, the seam is emphasized. Then, an image of the irradiated part is taken, and image processing is performed on the taken image data to detect a seam portion.

The fourth ERW pipe seam detecting device according to the present invention detects a seam of an ERW pipe whose surface is pickled or covered with black scale and whose seam is heated. In this case, the point light source emits light from a position vertically above the axis of the ERW tube. By irradiating in this manner, the seam portion is appropriately halated and emphasized. Then, the irradiated part is imaged, and image processing is performed on the imaged image data to detect a seam portion.

When the seam portion of the ERW pipe is detected by the fifth ERW pipe seam detection device according to the present invention, the traveling direction of the ERW pipe is measured from a position vertically above the axis of the ERW pipe. The main surface light source for irradiating obliquely, and located on both upper sides of the axis of the ERW pipe, in a direction orthogonal to the axis of the ERW pipe, and tilted so as to include the axis position of each ERW pipe. An auxiliary surface light source that irradiates the same range as the irradiation range of the main surface light source, and a point light source that irradiates the main surface light source and the irradiation range of the auxiliary surface light source approximately from the position vertically above the axis of the ERW tube. Irradiation is performed by switching or in combination depending on the surface condition of the electric resistance welded tube. By irradiating in this manner, the seam portion is appropriately halated and emphasized. Then, the irradiated part is imaged, and image processing is performed on the imaged image data to detect a seam portion.

According to the above-described apparatus, an appropriate seam portion can be detected by selecting an illumination in accordance with the surface condition of the ERW tube or switching the illumination, and the seam portion and its surroundings are not detected. Even with a clear ERW tube, only the seam portion can be accurately emphasized.

By the way, the conventional method does not take into account that the state of the seam changes when the bead cutting tool is replaced or when the size of the electric resistance welded pipe is changed, and therefore cannot cope with this change. At the time of these changes, the detection of the seam portion becomes impossible, and the seam portion manually enters the detection window range via the operator. Further, when the captured image is disturbed or the seam portion is out of the detection range, it is necessary to warn the operator, temporarily stop the line, and perform the manual alignment through the operator.

Therefore, a sixth electric resistance welded seam detecting apparatus according to the present invention includes, in addition to any one of the first to fifth devices, a seam detected by an image processing means. And a follow-up means for causing the illuminating means and the imaging means to follow the center of the seam determined by the center position calculating means.

When a seam portion is detected by using the sixth ERW pipe seam detecting apparatus according to the present invention, any one of the first to fifth ERW pipe seam detecting apparatuses described above is used. When imaging a part irradiated with light, first, a seam portion is detected by a first window set to a relatively large detection range, and then a seam portion detected by a second window set to a minimum required range is detected. Follow and image. Then, if necessary, the detection range of the second window is adjusted according to the seam width, or when the seam portion deviates from the second window, the first window is switched again to detect the seam portion.

As described above, the disadvantages that occur when the seam portion is detected in the conventional second window set in advance, for example, when the range of the detection window is too large, disturbance noise is easily picked up. It takes much time for image data processing, and when the detection window is too small, the problem that the seam portion is missed and detection becomes impossible does not occur.

The input setting of the image picked up as described above is switched and adjusted by the image inversion processing and the density conversion processing according to the surface state of the electric resistance welded tube, and the input setting is generated linearly in the imaged image data. If there is noise data of the flaws, the expansion / contraction filter processing is performed.If there is noise data generated in a hole shape, the hole filling filter processing is performed.If the seam portion is unclear, , A filter process for emphasizing the seam portion is performed.

According to the above method, when the detection target is determined to be white or black, and when the difference in black and white density is small with respect to a certain number of imaging pixels, the density range is determined by the histogram of the brightness level. By adjusting, the resolution is improved and the seam portion can be accurately detected. In addition, by performing a filtering process according to the noise situation on the surface of the ERW pipe, disturbance noise can be almost completely removed.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 schematically shows an ERW pipe manufacturing facility to which an ERW pipe seam detection method and apparatus (hereinafter, referred to as a seam detection method and a seam detection apparatus) of the present invention are applied. FIG. 2 shows a schematic configuration of the seam detection device. FIG.
Indicates an ERW pipe having a flaw or water droplet on the surface. FIG. 4 shows a surface state of the electric resistance welded tube. FIG. 5 shows a state of a detection window in the seam detection device. FIG. 6 is a flowchart illustrating the procedure of the seam detection method. FIG. 7 shows a detection state of the seam center position in the seam detection method.

In FIG. 1, a strip steel B is fed from the upstream to the downstream as indicated by arrows in the ERW pipe manufacturing facility 1. The steel strip B is passed through the forming roll group 2, and becomes an open pipe O curved in a cylindrical shape with opposite side edges. And open pipe O is squeeze roll 3
The two side edges are abutted, and the weld is welded by the welding device 4 while being heated and melted by the resistance heat of the current to form an ERW pipe P. The electric resistance welded pipe P thus subjected to the abutment welding is welded by the bead cutting device 5 (hereinafter referred to as a welded portion).
After the weld bead of the seam portion S) is cut, it is cooled in the cooling water tank 6.

The seam portion S of the electric resistance welded pipe P is detected by the seam portion detecting device 7, and the detected seam portion S is subjected to ultrasonic flaw detection by the ultrasonic flaw detector 8 for quality inspection. Thereafter, the electric resistance welded pipe P passes through the cooling water tank 9 again, is formed into a predetermined outer diameter by the sizer roll group 10, and is cut into a predetermined length by the cutoff machine 11. In performing the ultrasonic inspection of the electric resistance welded pipe P by the ultrasonic inspection device 8 in the above-described line, the probe of the ultrasonic inspection device 8 needs to correctly follow the seam portion S. The seam detection device 7 of the present invention has a configuration shown in FIG. 2 and a method described in detail below, in order to cause the probe of the ultrasonic flaw detector 8 to properly follow the seam S. The position of the seam portion S on the surface of P is detected.

That is, in FIG. 2, the seam detecting device 7 includes an illuminating unit (illuminating means) for irradiating the surface of the ERW tube P.
15. CCD camera (imaging means) 1 for imaging the irradiation position
6. An image processing unit (image processing means) 17 that performs image processing on a captured image to detect a seam portion S, calculates a center position of the seam portion S from the detected seam portion S, and controls each portion based on various information. It has a control unit 18 (center position calculating means) for controlling, and a follow-up mechanism 19 (follow-up means) for making the illumination unit 15 and the CCD camera 16 follow the center of the seam S. Further, the seam detection device 7 has a monitor 20 for monitoring the image processing status of the image processing unit 17. In FIG. 2, reference numeral 21 denotes an air purge for injecting a compressed gas toward the surface of the electric resistance welded pipe P in order to remove water droplets or vapor attached to a detection site, and 22 denotes a CCD camera 16. Is a polarization filter for the incident light, and M is a motor controlled by the tracking mechanism 19.

The illuminating section 15 sandwiches the axial center of the ERW pipe P with the main surface light source 23 which is disposed vertically above the axis of the ERW pipe P and is obliquely inclined in the traveling direction of the ERW pipe P. Auxiliary for irradiating an area approximately the same as the irradiation range of the main surface light source 23 by arranging it on the upper side on both sides in a direction perpendicular to the axis of the ERW pipe P and inclined so as to include the axis position of the ERW pipe P Surface light sources 24, 24 and a point light source 25 provided at a position vertically above the axis of the electric resistance welded pipe P and irradiating the substantially same range as the irradiation range of the main surface light source 23 and the auxiliary surface light sources 24, 24 are provided. . The dimming and on / off switching of the main surface light source 23, the auxiliary surface light sources 24, 24, and the point light source 25 are performed by a light source device (switching unit) 26 based on a control signal of the control unit 18. .

The seam detection device 7 having the above configuration switches the main surface light source 23, the auxiliary surface light sources 24, 24, and the point light source 25 of the illumination unit 15 in accordance with the surface condition of the electric resistance welded pipe P. A halation is generated such that the color difference (luminance difference) between the seam portion S and the periphery thereof is maximized on the surface, the illuminated portion is imaged by the CCD camera 16, and the image processing portion 17 performs image processing to form the seam portion S. Then, the illumination unit 15 and the CCD camera 16 follow the center of the seam S. It should be noted that the above-mentioned halation is difficult to detect if it is performed excessively, so it is adjusted to an appropriate illuminance in advance.

In the above configuration, as shown in FIG. 3, water droplets W, water vapor and the like adhered in the cooling water tank 6 adhere to the electric resistance welded pipe P, and cannot be completely removed by the air purge 21. Further, the electric resistance welded pipe P has roll flaws Q, dirt, and the like generated in the manufacturing process. If these are input as disturbance noise when the seam S is detected, it is difficult to determine the seam S. Further, since the surface of the electric resistance welded pipe P is not uniform due to various kinds of processing, the seam portion S is easily or hardly distinguished depending on the surface state. Therefore, in the seam detection device 7 of the present invention, the illumination is switched according to the surface state of the electric resistance welded pipe P, so that it is hardly affected by disturbance noise.
It is easy to distinguish between the seam portion S and its surroundings. That is,
The illuminating unit 15 irradiates a flat portion slightly formed on the seam portion S of the electric resistance welded pipe P when the weld bead is cut by the bead cutting device 5, and reflects the reflected light from the flat portion on the CCD.
The light enters the camera 16. Thereby, the seam portion S is appropriately halated and emphasized, and the noise can be largely cut.

The switching of the illumination unit 15 is performed based on the surface condition as shown in FIG. 4, for example. FIG. 4 (a)
Shows the seam portion S1 of the electric resistance welded pipe P1 and the periphery thereof. The electric resistance welded pipe P1 subjected to the pickling treatment is manufactured from a steel strip B that has been subjected to a surface scale removal treatment or the like after rolling. The surface condition is such that the seam portion S1 is black and the periphery thereof is generally white. It is an approximate color. FIG. 4B shows the seam portion S2 of the electric resistance welded tube P2 covered with black scale (scale) and its periphery. The electric resistance welded pipe P2 covered with black scale is made of strip steel B as hot rolled, and the surface condition is such that the seam portion S2 has a color similar to black, and the periphery thereof has scale. In general, the color is close to black.

FIG. 4C shows the seam portion S3 of the electric resistance welded pipe P3 after the pickling process and the heat treatment of the seam portion S, and the periphery thereof. FIG. 4D shows the seam portion S4 of the ERW pipe P4 covered with black scale and heat-treated at the seam portion S, and the periphery thereof. ERW pipe P which heat-treated these seams S
3 and P4, when manufacturing the electric resistance welded pipe P from the thick steel strip B, if the high-frequency heating is performed at once during welding, the whole is heated and cannot be efficiently welded. It is divided into high-frequency heating and the optimum temperature only for the welded part. Therefore, these ERW pipes P3 and P4 are connected to the seam portion S
3, S4 is a color or black that is close to black, and its periphery is a color that is close to black as a whole. Then, a dark blue streak and a spot peculiar to the heating part are generated on the periphery of the seam part S, and the surface state is complicated.

The electric resistance welded pipe P having a different surface condition as described above
Seams S1, S2, S3, S of 1, P2, P3, P4
4 and its surroundings, the illumination unit 1 of the seam detection device 7 of the present invention.
When the main surface light source 23, auxiliary surface light source 24, and point light source 25 of No. 5 are switched and irradiated, the results are as shown in (e) to (f) of FIG.
That is, FIG. 4E shows a state in which the main surface light source 23 and the auxiliary surface light sources 24, 24 are simultaneously radiated to the seam portion S1 of the electric resistance welded pipe P1 and the periphery thereof. FIG. 4F shows a state in which the main surface light source 23 and the auxiliary surface light sources 24, 24 are simultaneously radiated to the seam portion S2 of the electric resistance welded pipe P2 and the periphery thereof. FIG. 4 (g)
Is a point light source 2 at and around the seam portion S3 of the ERW pipe P3.
5 is irradiated. FIG. 4H shows a state in which the point light source 25 irradiates the seam portion S4 of the electric resistance welded pipe P4 and its periphery. As shown in these figures, if the illumination section 15 of the seam section detection device 7 of the present invention irradiates the illumination suitable for the surface of the ERW pipe P, the seam section S can be easily distinguished from the surrounding area.

Then, the seam S emphasized as described above and its periphery are imaged by the CCD camera 16, and image processing is performed to detect the seam S and the center position from this imaged area. Regarding the imaging area (detection range),
The switching is performed between the first window and the second window.
That is, first, as shown in FIG. 5A, a large detection range is set in the imaging area by the first window 7a, and thereafter, when the seam portion S is detected, FIG.
As shown in (b), the second window 7 of the detection range set to the minimum necessary size according to the width of the seam portion S.
b, and then following the seam S during the image processing as shown in FIG. 5 (c). In addition, when the width of the seam portion S changes while following the seam portion S, the second window 7b adjusts the detection range as shown in FIG.

Further, the second window 7b is connected to the second window 7b.
When the seam portion S deviates from the detection range of the window 7b,
Again, the detection range is switched to the first window 7a shown in FIG. 5A, and the seam S is detected. The reason why the first window 7a and the second window 7b are switched is that if image processing is performed on an unnecessarily large detection range in the subsequent image processing, the processing speed will be reduced. Thereby, the speed of image processing can be improved, and the seam portion S can be detected efficiently. The seam portion S in FIGS. 5A to 5D shows a state where the weld bead is gradually cut from an uncut state.

Next, the image processing section 17 in the detection range of the first window 7a and the second window 7b as described above.
The procedure of the processing of the image data in the above will be described in detail with reference to the flowchart of FIG. First, the image area itself captured by the CCD camera 16 is set as the detection range of the first window 7a (# 1), and the detection range of the first window 7a is captured (# 2). In the following image processing when the detection range of the first window 7a is captured, a binarization level for roughly detecting the seam portion S, a filtering method, and the like are determined in advance according to the surface state of the ERW pipe. Have been.

Next, the surface of the electric resistance welded pipe P judges whether or not the seam portion S has been subjected to the heat treatment (# 3).
Are heat-processed (YES in # 3), the black and white of the captured image is reversed (# 4), and the process proceeds to # 5. If the seam S is not heat-processed (# 3) And N
O), proceed to # 5. Regarding the image inversion processing corresponding to the captured image data in # 4, black and white inversion is automatically performed for the heat-treated seam portion S.
Concerning the density conversion processing performed between # 3 and # 5 or between # 4 and # 5, the processing is performed by setting the detection range of the first window 7a to a certain density range.

In step # 5, since the captured image is in the detection range of the first window 7a, the predetermined binarization level and filter processing are performed as described above. Then, the center position of the seam portion S in the first window 7a detected in # 5 is calculated by a preset calculation method (# 6), and it is determined whether or not the result is normal (# 7). If normal (YES in # 7), go to # 8, if abnormal (NO in # 7), return to # 1 and repeat the processing up to this point.

In step # 8, data such as the center position and the width of the seam portion S determined to be normal are output to the control portion 18 and other portions, and based on the output data, the first window 7a sends the data to the seam portion S. Switch to the second window 7b whose detection range is narrowed to the minimum necessary, and set it (# 9).
Return to

In step # 2, an image is taken in the range of the second window 7b. In the description of the processing for the detection range of the second window 7b, hereinafter, # 2 will be described as # 12, and # 3 to # 9 will also be described as # 12.
13 to # 19. Next, similarly to the above, it is determined whether or not the seam portion S of the electric resistance welded pipe P has been subjected to the heat treatment (# 1).
3) If the seam S has been heat-treated (# 1)
3) (YES at 3), # 15 of the captured image is inverted
If the seam portion S has not been heat-treated (NO in # 13), the flow proceeds to # 15.

In # 13, the density conversion process performed from # 3 to # 5 or # 4 to # 5 is set to a certain density range with respect to the detection range of the first window 7a. Processing was performed by
For the detection range of the window 7b, the density range is optimally set based on the histogram of the luminance level within the detection range, and the process proceeds to # 15.

Next, in step # 15, image processing corresponding to the surface condition of the ERW tube P is performed on the image whose density has been converted.
In other words, the surface image of the electric resistance welded pipe P, though almost cut by the illumination unit 15, may receive some noise. Therefore, in # 15, the input noise is almost completely removed by performing image processing.

In step # 15, the binarization level is appropriately changed according to the surface condition image of the ERW pipe P within the detection range of the second window 7b. For example, as shown in FIG.
And the periphery of the seam portion S2 is a color similar to black,
By setting the binarization level low, the seam S2 and the seam S are further changed from the state shown in FIG.
Black that is lower than the binarization level set for black around two can be clearly emphasized as white, and high black as black.

Further, in the present embodiment, various filtering processes are performed for noise removal and partial emphasis of the seam S in accordance with the above-described binarization level. In the filtering process, for example, when the target position (target pixel) is E as shown in Table 2 below, four pixels (B, D, F, H) or 8 pixels (B) around the target pixel E A, B, C, D, F,
G, H, I), and switches between the 4-neighbor or 8-neighbor processing for finding the value of the new target pixel E by referring to the value of the target pixel E, and optimizes the following filter processing in the optimal direction of the detection range in the X or Y direction It was performed several times.

[0055]

[Table 2]

The filter processing for noise removal is performed, for example, on noise data such as linearly generated flaws.
A contraction process is performed, and a hole filling process is performed on noise data generated in a hole shape such as a water drop, for example. In the expansion process, for example, for the target pixel E in Table 2, E = MAX (A, B, C, D, E, F, G, I) is performed an optimum number of times in the X or Y direction in the 8-neighbor process. In the contraction process, for example, E = MIN (A, B, C, D, E, F, G, I) is performed an optimum number of times in the X or Y direction in the 8-neighbor process for the target pixel E. Furthermore, in the hole filling process, for example, when there is a hole-shaped noise data in the target pixel E, a new target pixel E is obtained from the reference value in the vicinity of 4 or 8 referred to in the 4-neighbor or 8-neighbor process, and this process is performed by X Alternatively, the noise at the target pixel E before processing is filled by performing the optimal number of times in the Y direction.

Further, when it is necessary to further emphasize the seam portion S, a partial emphasis process by sharpening, differentiating, and Kirsch processes is performed. For example, in the sharpening process, for the target pixel E, E = 5E-BDFH is performed an optimum number of times in the X or Y direction in the 8-neighbor process. In the differentiation process, E = ABS (ED) is performed on the target pixel E an optimum number of times. In addition, Kirsch processing,
For target pixel E, E = 5A-3B-3C + 5D-3F + 5G-3H-3I
Alternatively, the process is performed an optimum number of times in the Y direction. By performing these processes, disturbance noise can be almost completely removed, and the seam portion S is further emphasized. Of course, the above-described processing method is merely an example, and the seam detection device 7 has a data table that can correspond to various surface states of the ERW pipe, and selects these optimally and performs the optimal round processing. Thus, the detection accuracy of the seam portion S does not decrease.

Then, the accurate position of the seam S in the detection range of the second window 7b optimally processed in # 15 is detected, and the center position of the seam S is calculated (# 16). This center position is calculated by calculating the center coordinates from the maximum and minimum coordinate positions in the width direction of the seam portion S, and adding the minimum coordinates to the center coordinates (subtracted from the maximum coordinates), as shown in Expression 1 below. Is the center coordinate of the seam portion S, or the rising (the first change point in the X direction) and the falling (the X direction) in the threshold from the luminance distribution in the width direction of the seam portion S as shown in Expression 2. Projection addition measurement for obtaining the center position with reference to the (last change point) is used.

[0059]

[Equation 1] Seam center position = {(Xmax-Xmin) / 2} + Xmin

[0060]

[Equation 2] Threshold = [｛(maximum luminance value−minimum luminance value) ×
Threshold {/ 100] + minimum luminance seam center position = {(last change point position−first change point position) / 2} + first change point position

These are, for example, shown in FIGS.
When the image of the seam S is stable, the fillet diameter measurement is used, and when the image of the seam S is not stable, as shown in FIGS. It is sufficient to select and use the most appropriate one according to the situation, such as using addition measurement.

FIG. 7 shows a state where the center of the seam S is calculated. FIG. 7A shows a state in which the seam center is calculated from both edges of the seam portion S within the detection range of the second window 7b by the fillet diameter measurement or the projection addition measurement, which is the procedure described above. 5 shows a state in which the center of the seam portion S is calculated from the position of the center of gravity of the black portion in the measurement window detection range, which is a conventional procedure. In FIG. 7A, the portions indicated by solid lines and solid arrows are the center positions of the seam edge and the seam portion S, and the center positions of the seam edge and the seam portion S actually detected by the method and the apparatus of the present invention. . On the other hand, in FIG. 7B, the portions indicated by solid lines and solid arrows are the center positions of the seam edge and the seam portion S, and the broken lines are the center positions of the seam edge and the seam portion S actually detected by the conventional method and apparatus. It is. As is clear from the comparison between (a) and (b) of FIG.
The method of the present invention accurately detects the edge of the seam portion S,
In addition, since the fillet diameter measurement method and the projection addition measurement method are selectively used depending on the luminance situation inside the seam portion S, and the center of the seam portion S is calculated based on the seam edge, no error occurs unlike the related art.

Next, it is determined whether or not the information on the center position of the seam S obtained in # 16 is normal (# 17). If the information is normal (YES in # 17), the flow proceeds to # 18. Also, # 1
If the determination of 7 is abnormal (NO in # 17), the process returns to # 1, switches to the first window 7a again, and performs detection.
The processing up to this point is repeated. After the measurement is determined to be normal in # 17, the control unit 18 controls each unit based on the center position information of the seam S (# 18), and sets the next second window 7b next time. (# 19) Then, the process returns to # 12 and captures an image in the detection range of the next second window 7b.

It should be noted that the above-mentioned control unit 18 uses a unit having a high processing performance, so that the above-described judgment, calculation,
And switching is performed instantaneously. Further, based on the center position of the seam S calculated by the above process, the control unit 18 follows the CCD camera 16 and
In order to follow the center of the seam S such as the main surface light source 23, the auxiliary surface light sources 24, 24, and the point light source 25, switch according to the surface state of the electric resistance welded pipe P, and follow the air purge 21, A signal is sent to 19. Also, the control unit 18
A follow-up signal is also output to the ultrasonic flaw detector 8 to cause the probe to follow the seam portion S. Further, the motor M is driven at a high speed, and each portion follows the seam portion S continuously. Further, if an abnormality occurs in the measurement in steps # 7 and # 17 in the above procedure, the control unit 18 outputs a warning by sound or display on the monitor 20, and pays attention to the operator while performing the following processing. Prompt.

As described above, the seam detection device 7
Problems of the conventional apparatus for optically detecting the seam S, such as the influence of disturbance noise and the difference in the surface condition of the ERW pipe (including noise countermeasures, of course), etc. Poor detection accuracy can be dramatically improved. As a result of detecting the seam portion S by the seam portion detection device 7 based on the above embodiment, the center position measurement of the seam portion S of the ERW pipe P manufactured at a pipeline speed of 100 m / min is within ± 0.5 mm. The accuracy of the image processing detection at that time was an error of about 0.08 mm.

As described above, the seam portion detecting device 7 switches the illumination according to the surface state of the electric resistance welded pipe P so that the seam portion S and its surroundings can be applied to the electric resistance welded pipe P having a different surface state. Image data that can be clearly identified, and furthermore, by performing an optimal filtering process on the image data in accordance with the noise, disturbance noise is almost completely removed, and the seam portion S is accurately detected. can do. Therefore, the ultrasonic inspection device 8 can appropriately perform ultrasonic inspection on the electric resistance welded pipe P. Further, various settings in the seam detection device 7 are set according to various information of the electric resistance welded pipe P, and the seam S is automatically detected again by the seam detection device 7 even when the seam S is deviated from the seam S. The production line for the ERW pipe P can be almost completely automated.

The above-described embodiment includes a seam portion corresponding to a device having the structure of claim 11, including the method of claim 9, the method of claim 10, and the device of claim 5. Although the detection device 7 has been described as an example, depending on the line of the ERW pipe P to be manufactured, for example, claims 1 to 5 may be used.
The detection of the seam portion S may be performed as a mode in which claim 11 is added to any of the devices.
In such a case, the first window 7a and the second window 7b according to claims 6 to 8, the setting of switching adjustment of the image inversion processing and the density conversion processing according to claim 9, and a combination of the filter processing according to claim 10 Also, the settings may be appropriately changed so that the seam portion S can be detected optimally.

[0068]

As described above, claims 1 to 5 of the present invention.
According to the electric resistance welded seam detecting device of the present invention, in order to make it possible to distinguish the seam part of the electric resistance welded pipe from its surroundings, an electric resistance welded pipe whose surface is pickled and an electric resistance welded surface whose surface is covered with black scale A main surface light source, an auxiliary surface, for each surface or according to each surface of an electric resistance welded tube whose surface is pickled or covered with black scale and whose seam portion is heat-treated. The seam is detected by irradiating the electric resistance welded tube with the light source and the optimum light source combined with any one of the point light sources or by switching to the optimum light source combined with any one thereof, and detecting the seam portion. Is enhanced using halation, so that noise such as water droplets and scratches can be prevented from being input as image data, and the seam can be accurately detected without being affected by disturbance noise, and the detection accuracy can be improved. Can be improved That.

Further, according to the electric resistance welded seam detecting method of the sixth aspect of the present invention and the electric resistance welded seam detecting apparatus of the eleventh aspect of the present invention, first, the seam portion is set in the first window set to a relatively large detection range. Is detected, and then the seam portion is imaged following the second window set to the minimum necessary range, thereby preventing a reduction in processing speed caused by detecting the seam portion in an unnecessarily large detection range. can do. In addition, since the illumination means and the imaging means follow the center of the seam part obtained by calculating the center position from the seam part thus detected, the seam part moves in the circumferential direction of the ERW pipe. However, the seam portion can always be illuminated and imaged in an optimal state, and therefore, the seam portion detection accuracy is improved.

According to the electric resistance welded seam detecting method of the present invention and the electric resistance welded seam detecting device of the present invention, the detection range of the second window is adjusted according to the seam width. Therefore, there is no problem that detection is performed in an unnecessarily large detection range in spite of a small seam width, and detection is performed in a small detection range in spite of a large seam width. Can be detected. In addition, since the illumination means and the imaging means follow the center of the seam obtained by calculating the center position from the seam thus detected, the same operation and effect as described above can be obtained.

Further, according to the electric resistance welded seam detecting method of the eighth aspect of the present invention and the electric resistance welded seam detecting apparatus of the eleventh aspect, when the seam comes off the second window,
Since the seam portion is detected by switching to the first window again, the detached seam portion can be reliably and immediately detected. If the seam portion is detected, the seam portion is switched to the second window.
The seam does not become undetectable. In addition, since the illumination means and the imaging means follow the center of the seam obtained by calculating the center position from the seam thus detected, the same operation and effect as described above can be obtained.

According to the electric resistance welded seam detecting method of the ninth aspect of the present invention and the electric resistance welded seam detecting apparatus of the eleventh aspect of the present invention, the input setting of the captured image is performed by changing the surface state of the electric resistance welded pipe. In the image inversion processing and the density conversion processing, the switching is adjusted in accordance with the condition (1), so that the captured image can clearly determine the seam portion and its surroundings, and can always be sent to the next image processing step in an optimal state. In addition, since the illumination means and the imaging means follow the center of the seam part calculated by calculating the center position from the seam part detected in this way,
The same operation and effect as described above can be obtained.

Further, according to the electric resistance welded seam portion detecting method of the tenth aspect of the present invention and the electric resistance welded seam detecting device of the eleventh aspect of the present invention, the surface of the electric resistance welded pipe is provided with a line-shaped flaw or the like. When there is noise data, expansion / contraction filter processing is performed. When there is noise data generated in a hole shape due to water droplets or the like, hole filling filter processing is performed. When the seam part is unclear, seam processing is performed. Since the filter processing that emphasizes the part is performed, the seam part and its surroundings can be clearly distinguished,
The detection error can be significantly reduced. In addition, since the illumination means and the imaging means follow the center of the seam obtained by calculating the center position from the seam thus detected, the same operation and effect as described above can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an ERW pipe manufacturing facility to which an ERW pipe seam detection method and apparatus according to an embodiment of the present invention are applied.

FIGS. 2A and 2B show an electric resistance welded tube seam detecting device according to an embodiment of the present invention, wherein FIG.
FIG. 3 is a diagram viewed from the side of the electric resistance welded tube.

FIG. 3 is a diagram showing a state of disturbance noise in a seam portion on the surface of an electric resistance welded tube and its periphery.

FIG. 4 shows a seam portion and its surrounding state which are different depending on the surface treatment of the electric resistance welded tube. FIG.
Is an electric resistance welded pipe covered with black scale, (c) is an electric resistance welded pipe which has been pickled and heat-treated at the seam portion, (d) is covered with black scale,
And it is an electric resistance welded tube whose seam part is heat-treated,
(E) is a state of irradiation from a light source optimal to (a), (f)
(G) is a state illuminated from the optimal light source in (c), (h) is a state illuminated from the optimal light source (b).
FIG. 7 is a diagram of a state where light is emitted from a light source most suitable for the present invention.

FIGS. 5 (a) to 5 (d) show a first window and a second window in the ERW pipe seam detecting method according to the embodiment of the present invention, wherein the first window follows the seam and the width is changed; It is a figure showing the state where it adjusted.

FIG. 6 is a flowchart illustrating a method for detecting an electric resistance welded seam portion according to an embodiment of the present invention.

FIGS. 7A and 7B are diagrams showing a situation when an edge of a seam portion and its center are detected, wherein FIG. 7A shows a situation according to the seam detection method of the present invention, and FIG. 7B shows a situation according to a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ERW pipe manufacturing equipment 7 Seam part detection device 7a 1st window 7b 2nd window 8 Ultrasonic flaw detector 15 Illumination unit 16 CCD camera 17 Image processing unit 18 Control unit 19 Follow-up mechanism 20 Monitor 23 Main surface light source 24 Auxiliary surface light source 25 point light source 26 light source device P ERW pipe S seam

Claims (11)

[Claims] 1. An apparatus for detecting a seam portion of an electric resistance welded pipe whose surface has been pickled, and illuminating means for irradiating the surface of the electric resistance welded pipe, and imaging a position illuminated by the illumination means. An image pickup unit, and an image processing unit for performing image processing on an image picked up by the image pickup unit and detecting a seam portion, wherein the illuminating unit is provided at a position vertically above the axis of the electric resistance welded tube. An electric resistance welded tube seam detection device, wherein the irradiation is performed using a main surface light source arranged obliquely in the traveling direction. 2. An apparatus for detecting a seam portion of an electric resistance welded tube whose surface has been pickled or covered with a black scale, wherein
In place of the main surface light source of the ERW pipe seam detecting device described above, it is located on both upper sides with respect to the axis of the ERW pipe, in the direction perpendicular to the axis of the ERW pipe, and the axial position of each ERW pipe. An electric resistance welded seam portion detecting device, characterized in that an auxiliary surface light source is used which is disposed so as to be irradiated so as to irradiate. 3. The electric resistance welded seam detecting device according to claim 2, wherein the auxiliary electric field light source is replaced with the auxiliary surface light source at a position vertically above the axis of the electric resistance welded pipe so as to be obliquely inclined in the traveling direction of the electric resistance welded pipe. The main surface light source and the main surface light source are located on both sides above the axis of the ERW tube, in a direction perpendicular to the axis of the ERW tube, and each include the axial position of the ERW tube, and substantially the same as the main surface light source. An electric resistance welded seam portion detecting device, characterized by using an auxiliary surface light source which is arranged to be inclined so as to irradiate an area. 4. A device for detecting a seam portion of an electric resistance welded tube whose surface is pickled and whose seam portion is heat-treated, or a seam portion of the electric resistance welded tube whose seam portion is covered with black scale and the seam portion is heat-treated. An electric resistance welded seam portion, wherein a point light source irradiating from a position vertically above the axis of the electric resistance welded tube is used instead of the main surface light source of the electric resistance welded seam portion detecting device according to claim 1. Detection device. 5. A main surface light source disposed at a position vertically above the axis of the ERW tube and inclined obliquely in the traveling direction of the ERW tube. It is located on both upper sides with the axis of the ERW tube downstream of the main surface light source to irradiate substantially the same range as the illumination range of this main surface light source, in the direction orthogonal to the axis of the ERW tube, and An auxiliary surface light source for tilting and irradiating so as to include the axial position of the electric resistance welded tube; and a range substantially the same as the irradiation range of the main surface light source and the auxiliary surface light source from a position vertically above the axis of the electric resistance welded tube to a position immediately below the same. An electric resistance welded seam detecting device, comprising: a point light source for irradiating light; and switching means for switching these light sources in accordance with the surface state of the electric resistance welded tube. 6. A seam portion of an electric resistance welded tube and its periphery.
A light is radiated using the illuminating means according to any one of (1) to (5), an image of the illuminated part is taken, and image processing is performed on the taken image data to detect a seam part. First, a seam portion is detected by a first window set to a large detection range, and then the detected seam portion is imaged by following a second window set to a minimum necessary detection range. An electric resistance welded seam detection method. 7. The method according to claim 6, wherein the detection range of the second window is adjusted according to the seam width. 8. The ERW pipe seam detection according to claim 6, wherein, when the seam deviates from the second window, the detection range is switched to the first window again to detect the seam. Method. 9. The electric resistance welding according to claim 6, wherein the input setting of the captured image is switched and adjusted by an image inversion process and a density conversion process according to the surface state of the electric resistance welded tube. Tube seam detection method. 10. When image data of picked-up image includes noise data of a linearly generated flaw, expansion / contraction filter processing is performed. When noise data generated in a hole is present, Perform fill-in-the-blank filter processing, and
The method according to any one of claims 6 to 9, wherein when the seam portion is unclear, a filter process for enhancing the seam portion is performed. 11. An electric resistance welded seam detecting apparatus according to claim 1, further comprising: a center position calculating means for calculating a center position of the seam from the seam detected by the image processing means; 11. An electric resistance welded seam according to claim 6, further comprising a follow-up means for causing the illumination means and the imaging means to follow the center of the seam portion obtained by the center position calculating means. Apparatus applied to the part detection method.