JPH0740049A - UO steel pipe weld detection method and apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] To accurately detect the weld position and width of UO steel pipe. [Arrangement] Projector for irradiating slit light to the UO steel pipe welded portion and its vicinity; Imaging device for capturing slit light to obtain a light-section image;
The difference data is subjected to an emphasis process, the emphasis data is further subjected to a difference process II, and the peak position of the difference data obtained in the difference process II is extracted as one end of the welding width. Position of both ends,
It is characterized by having a calculator for calculating the width and the center position of the width.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a UO steel pipe weld portion position detecting method for detecting the position of the weld portion by photographing the vicinity of the UO steel pipe weld portion by an optical cutting method, and a UO steel pipe weld portion for measuring the width of the weld portion. Width detection method.

[0002]

2. Description of the Related Art As a conventional technique for detecting a welding line of a welded steel pipe, there is, for example, a method disclosed in Japanese Patent Publication No. 03-32434. This technique draws a line of fluorescent paint from the welding position to the valley side in the circumferential direction at a predetermined angle position at the closest distance of the welding machine, reads the fluorescent line on the downstream side, and checks the position of the predetermined angle position to the mountain side in the circumferential direction. A method and apparatus for detecting and following a welding line of a welded steel pipe, which improves accuracy by determining the position of the welding line.

[0003]

The above-mentioned prior art is directed to the electric resistance welded steel pipe. As a method of manufacturing an electric resistance welded steel pipe, a hot rolled coil slitted to a predetermined width corresponding to the diameter of the steel pipe is unwound by an uncoiler while being rewound by a forming roll into a steel pipe having both ends of the width of the hot rolled coil butted against each other. Formed and welded, through ultrasonic flaw detection of welds, heat treatment of welds, sizing, straightener, etc.,
It is common to cut to a predetermined length by a traveling cutting machine at the end of the pipe making step. However, since the electric resistance welded steel pipe is connected with a continuous material from the uncoiler to the traveling cutting machine, and the welded part is usually on the upper side, even if the steel pipe welded part is slightly twisted during transfer, it is on the top surface and transferred. It does not come into contact with rolls. In ultrasonic flaw detection and weld heat treatment, etc. that require detection and tracking of the welding line in the above pipe making process, a predetermined angle from the welding position to the valley side in the circumferential direction at the closest distance of the welding machine according to the conventional technique. It is considered that the fluorescent paint drawn at the position is stored in a substantially clear state.

On the other hand, in the method for manufacturing a UO steel pipe, a single thick plate is formed into a tubular shape by a U press and an O press, the inner and outer surfaces are welded, and then conveyed to a rear inspection step. That is, since the UO steel pipes are manufactured one by one, as a method of conveying each step of pipe making, a method of laterally overturning and a method of using a conveying roll are often used. Therefore,
Draw the fluorescent paint by the method shown in the prior art by contact with the kick down when rolling over, contact with the turning roll when rotating the steel pipe, and contact with the transport roll because the weld is not always facing upward. Even if it is carried out, the drawing paint may become unclear due to the adhesion of dirt during transport and the peeling of the paint due to the contact, and the reliability of detection tracking may be significantly reduced.

An object of the present invention is to accurately detect the position of a welded portion of a UO steel pipe.

[0006]

The device of the present invention has been made to solve the problems of the prior art, and a projector for irradiating a UO steel pipe welded portion and its vicinity with a slit light, and the slit light. An image pickup device for capturing an image to obtain a light section image, and a computer for performing processing such as thinning and difference on the light section image, detecting a weld end position, and measuring a weld width Is characterized by.

The present invention relates to a method for irradiating a UO steel pipe welded portion and its vicinity with slit light and detecting the position of the welded portion using a light section image obtained by photographing the slit light with an image pickup device. Thinning the light-section image to obtain thinning data, subtracting the thinning data to obtain difference data,
The difference data is emphasized to obtain difference emphasis data, and the welding part end position position is detected using the welding part end part emphasis data obtained by performing the difference process on the difference emphasis data string to thereby detect the weld part. It is characterized in that the position is detected and the weld width is measured.

[0008]

In the present invention, since the build-up shape of the welded portion is directly detected by the light cutting method, the drawing with fluorescent paint or the like as shown in the above-mentioned prior art is not necessary, and the adherence of dirt and the roll during transportation. It is possible to prevent the detection reliability from being deteriorated due to the drawing paint being unclear due to the peeling of the paint due to contact with the like. Further, by emphasizing and detecting both ends of the welded portion, the position of the welded portion can be detected and the width of the welded portion can be measured.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, 1 is a UO steel pipe and 2 is its weld. The slit light projector 3 projects slit light to the welded portion and its vicinity to form a slit light image 4 on the surface of the UO steel pipe 1, and the image pickup devices 5a and 5b are arranged at positions where the slit light image 4 is obliquely captured. To do. Here, although the case where the welded portion on the outer surface of the UO steel pipe is detected is shown, a slit light image may be formed on the welded portion on the inner surface and the vicinity thereof in the case of the inner surface as well. As the slit light projector 3, for example, as shown in FIG. 2, a laser diode 12 is caused to emit light, a collimator lens 13 collects the laser light, and a cylindrical lens 14 spreads the laser light into a fan shape to form slit light. Is used to form a slit light image 4 having a half width of, for example, about 0.1 mm.

As the image pickup devices 5a and 5b, for example, CC
A D camera is used. Since it is desired that the image pickup devices 5a and 5b have sufficient resolution, in this embodiment, the field of view per image pickup device is limited to the end of the welded portion (half the width of the welded portion), and the left and right ones respectively. Two imaging devices are provided, but if sufficient resolution can be obtained, the number of imaging devices will be one.
It may be used as a stand.

In the welded portion of the UO steel pipe, the base metal portion is usually overlaid. Therefore, the imaging device 5a,
5b, the line AA ′ and the line B- shown in FIG.
When the slit light image 4 of the B ′ line portion is photographed, light cut images 21 and 22 as shown in FIGS. 3B and 3C are obtained by the principle of the light cutting method. These light section images 21 and 22 are input to the welded part detection processing unit 6 (FIG. 1).

In the welded portion detection processing portion 6 shown in FIG. 1, the light section image 21 is A / D stored in the image storage portion 7a.
It is converted and stored as a two-dimensional digital value P _L (x, y). At the same time, the light section image 22 is A / D converted in the image storage section 7b to obtain a two-dimensional digital value P _R (x, y).
Memorize as.

Next, thinning processing is performed by the thinning processing units 8a and 8b. FIG. 4 shows the thinning processing in detail. Here, the two-dimensional image data P _L (x,
y) will be described. Two-dimensional image data P shown in FIG.
A process for selecting a point having the maximum brightness on one line in the screen y direction for _L (x, y) is advanced in the screen x direction, and a thin line in which the y coordinate values of the maximum brightness points corresponding to the x coordinates are arranged. An encoded data string S _L (x) is obtained. At this time, if the brightness of the point selected as the maximum brightness does not reach the brightness threshold value so as to prevent noise outside the slit image from being erroneously selected for a portion with low brightness of the slit image, the maximum brightness in the immediately preceding line The same value as the y coordinate of the point is set to prevent the thinned data from deviating from the slit image. For example, if the brightness at the maximum brightness point of the line of x _m is below the threshold value, S _L
The value of S _L (x _m-1 ) is entered in (x _m ). The same processing is performed on the two-dimensional image data P _R (x, y) and S _R (x)
To get Next, the data string computing unit 9 detects the weld edge based on the thinned data strings S _L (x) and S _R (x) and calculates the weld position and the weld width. explain. Since the same processing is performed for S _L (x) and S _R (x),
In the following, explanations will be given using symbols that omit the subscripts _L and _R.

First, the difference processing I of the thinned data string S (x) will be described with reference to FIG. First, an appropriate number of pixels Δx is set, and a certain point A (x _A , on the thinned data string S (x),
S (x _A )) and Δx separated points B (x _B , S (x _B ))
And the difference element C ((x _A + x _B ) / 2, S (x _B ) −S
(X _A )) is calculated. This calculation is performed over the entire x coordinate to create a difference data string D (x) in which difference elements C are arranged. The value of the element of the difference data string D (x) takes a positive value in the rising portion of the welding portion and a negative value in the falling portion of the welding portion.

Next, the emphasis processing of the difference data string D (x) will be described with reference to FIG. Here, the difference data string D
The moving sum operation of k consecutive data of (x) is

[0016]

[Equation 1]

As a whole, the emphasizing data sequence E in which the rising and falling portions of the welded portion are further emphasized is performed over the entire x coordinate.
Create (x). Further, the difference data II is applied to the emphasized data string E (x) to create the weld edge detection data string F (x). The data string F (x) is shown in FIG. Difference processing II
Is the same as the difference processing I (FIG. 5) described above, and the weld edge detection data string F (x) obtained by performing the difference processing II on the emphasized data string E (x) is , X that almost coincided with the rising and falling end positions of the weld x
The value takes a positive peak in the coordinates. As shown in FIG.
X takes a positive peak in the weld edge detection data string F (x)
By considering the coordinate value as the weld end position and taking x _L and x _R as x coordinates corresponding to the left and right ends of the weld,
It is the position of the end of the welded portion in the imaging visual field range of the imaging devices 5a and 5b.

When the weld end positions x _L and x _R are obtained in this manner, the positions of the image pickup devices 5a and 5b are fixed, and the x coordinate between both image pickup devices is calibrated in advance, It is possible to calculate the welded portion position (left end portion, right end portion, center) with respect to the imaging devices 5a and 5b. Further, the width of the welded portion can be measured based on the positions of the left end portion and the right end portion of the welded portion.

Next, an example in which specific numerical values are set and defects are inspected in the above-described embodiment will be described. The slit light projector 3 uses a 20 mW laser diode for 2 ms.
It lights up with a pulse in the ec cycle, and the imaging device (5a, 5b) has 2
Using a single CCD camera, the surface of the steel pipe including the slit light image 4 is imaged as a 256-tone grayscale image in a visual field of 32 mm in the width direction and 45 mm in the height direction, and then 512 images are obtained.
Processing was performed using the image processing device 6 having × 512 pixels × 2 screens. When the brightness threshold in the data string arithmetic unit is set to 5 and the difference interval Δx = 8 is set, and the number of pixels of the moving sum of the emphasis process is set to k = 6 to detect the end of the welded portion of the UO steel pipe, the result is 1 mm or more. The end of the weld having the build-up height was detected reliably.

[0020]

As described above, according to the weld end detecting device and method of the UO steel pipe of the present invention, the position of the welded UO steel pipe weld can be detected with high reliability and the weld can be detected. The width of can be measured. Further, by inputting the UO steel pipe welded portion position signal detected by the present invention to the external device and moving the external device based on the signal, the external device can be made to follow the welded portion. For example, U
When applied to a device for ultrasonically flaw-detecting a welded portion while moving the O steel pipe in the longitudinal direction, flaw-finding at a desired position on the cross section of the welded portion can be performed accurately.

[Brief description of drawings]

FIG. 1 shows an outline of an apparatus configuration for carrying out the present invention in one aspect, and includes a UO steel tube 1, a floodlight 3 and imaging devices 5a and 5b.
3 is a perspective view showing the external appearance of FIG. 1 and a block diagram showing the configuration of the image processing device 6. FIG. Block Diagram FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing an internal configuration of the projector 3 shown in FIG.

3A is an enlarged perspective view showing a part of the UO steel pipe 1 shown in FIG. 1, FIG. 3B is a plan view showing a photographed image of the image pickup device 5a shown in FIG. 1, and FIG. Imaging device 5b shown in FIG.
It is a top view which shows the picked-up image.

4A and 4B are a plan view showing a photographed image of the image pickup apparatus 5a shown in FIG. 1 and a graph showing a luminance distribution of one line of thinned image information obtained by thinning the photographed image information.

5 is a plan view showing an image represented by the thinned image information and a graph showing a level distribution in the x direction on the screen of difference data obtained by performing difference processing I on the information, FIG. Based on the captured image information of the image pickup device 5a shown in
(B) shows one based on the captured image information of the imaging device 5b shown in FIG.

FIG. 6 is a graph showing a level distribution of difference data in the x direction on the screen and a graph showing a level distribution of emphasis data obtained by performing an emphasis process on the difference data, and FIG. What is based on the captured image information of the imaging device 5a shown in 1 is
(B) shows one based on the captured image information of the imaging device 5b shown in FIG.

7A and 7B are a graph showing a level distribution of emphasis data and a graph showing a level distribution in the x direction on the screen of difference data obtained by difference processing II of the emphasis data. What is based on the captured image information of the imaging device 5a shown in 1 is
(B) shows one based on the captured image information of the imaging device 5b shown in FIG.

[Explanation of symbols]

1: UO steel pipe 2: UO steel pipe welded part 3: Slit light projector 4: Slit light image 5a: Imaging device 5b: Imaging device 6: Welded part detection processing part 7a: Image storage part 7b: Image storage part 8a: Thinning process Part 8b: Thinning processing part 9: Data string calculation part 12: Laser diode 13: Collimator lens 14: Cylindrical lens 21: Slit light image on photographed image 22: Light image on photographed image

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[Procedure amendment]

[Submission date] August 16, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

Claims (2)

[Claims] 1. A method of irradiating a UO steel pipe welded portion and its vicinity with slit light and detecting the position of the welded portion by using a light cut image obtained by imaging the slit light with an image pickup device. The image is thinned to obtain thinned data, the thinned data is subjected to difference processing to obtain difference data, the difference data is emphasized to obtain difference emphasized data, and the difference emphasized data string is further subjected to difference processing. The welded portion of the UO steel pipe is characterized in that the welded portion end position is detected by using the welded portion end emphasis data obtained by Detection method. 2. A light projector for irradiating a UO steel pipe welded portion and its vicinity with slit light, an image pickup device for capturing the slit light to obtain a light section image, the light section image being subjected to thinning and differential processing, and the welded section. A welded part detection device for a UO steel pipe, comprising a computer for detecting an end position and / or measuring a welded part width.