JPS61269007A - Measurement for weld part step of welded pipe - Google Patents

Abstract

PURPOSE:To calculate a weld part step from the separation distance between a light cut image and a reference position, by using an image detector comprising a group of photoelectric conversion elements arrayed tow-dimensionally while the center position of the weld part as reference is determined with a separate position detector. CONSTITUTION:The weld part W of a pipe P is irradiated with a slit light source L to obtain an image of a light-cutting line C on a detector D comprising a group of fine photoelectric conversion elements and a separated weld position detector T is arranged. The horizontal axis of the section of the pipe is set as X and the vertical axis thereof as Y and coordinates at points (photoelectric conversion elements) of a light cut image Pr are determined. An equation is obtained to indicate the profile of the pipe circumferential surface on both sides of the weld part and in the butt position, the weld part step W0 can be determined from the difference between right and left Y coordinate values at the coordinate X=0. From the results of the detection of the center position of the weld part, X-Y coordinate is converted to correct deviation in the weld center due to vibration and twist of the pipe and a computation is performed. By this method, the measurement of the weld part can be done at a high speed with a high accuracy.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for measuring the level difference in a welded part of a welded pipe.

(Prior art) The welded part level difference in a welded pipe, that is, the welded part level difference caused by the misalignment of the guide pipe before welding, has a large relationship with the quality of the welded part of the pipe, and is one of the important control items in the welded pipe manufacturing process. It is. As a conventional method for measuring this welding level difference during the manufacture of a welded pipe, there is a method described in Japanese Patent Application Laid-open No. 137801/1983. In this method, a photo-cutting image obtained by irradiating the welded part of the pipe and its vicinity with a slit light is sequentially stored in a frame memory as a video signal obtained each time it is scanned by a scanner photoelectric conversion receiver. Later, this is read out sequentially to determine the X-Y coordinates of the point where the maximum brightness is obtained, and sequentially stored in a dimensional mesori, and this is repeated for all video signals.From the data in the one-dimensional memory obtained, both sides of the welded part are Equation of the circle on the outer circumferential surface of (Y, =GL←).

This is a method of determining the step of the welded part from the difference IY, -Y21 between the two.

(Problems to be Solved by the Invention) It is of course possible to measure the weld level difference using the conventional method described above, but when calculating the equation of the profile of the outer peripheral surface of the pipe on both sides of the weld, it is difficult to measure the weld and Each scanning video signal of the optically sectioned image in the vicinity is sequentially stored in a frame memory, and then sequentially read out to determine the X-Y coordinates of the point where the maximum brightness is obtained, and sequentially stored in a -dimensional memory; This process is repeated for all video signals, and from the data in the one-dimensional memory obtained, an equation for the profile of the tube's outer peripheral surface on both sides of the weld is calculated, and the weld step is calculated from the difference between the two, resulting in extremely complex table signal processing. Another problem is that it takes a long time to obtain one piece of step value data, making the conventional method unsuitable for online measurement.

In addition, when calculating the profile equation, it is necessary to exclude the range corresponding to the weld bead part from the optically sectioned image, but in the conventional method, the data in the -dimensional memory is used to determine the weld bead part. Because this method calculates the maximum height point of the weld bead and the positions of both ends of the weld bead from the shape characteristics of The problem was that it could only be applied in

Therefore, the present invention has developed a method for measuring the step of a weld that can quickly calculate an equation representing the profile of the outer circumferential surface on both sides of the weld using a relatively simple device configuration, and that can be applied even after cutting the weld bead. This is what we are trying to provide.

(Means for Solving the Problems) That is, the present invention, when measuring the welded part level difference of a welded pipe, uses A slit light is irradiated, a photocutting image is detected by a detector consisting of a group of two-dimensionally arranged photoelectric conversion elements provided above the irradiated part, and the separation distance between each point of the photocutting image and a reference position is detected; A welding position detector installed near the irradiated part detects the welding part center position, and the respective distance detection values on both sides excluding a certain range including the welding center position from the separation distance detection values are calculated. The method is characterized in that an equation representing the profile of the outer circumferential surface of the object to be measured on both sides of the weld is determined from a series of equations, and the step of the weld is determined from the difference between the solutions of the cough equation at a position corresponding to the center position of the weld. This is a method for measuring the level difference in the welded part of a welded pipe.

(Example and operation) The present invention will be described in detail below using an example in which the present invention is applied to measuring a welded part level difference in a manufacturing process of an electric resistance welded steel pipe.

FIG. 1 is a diagram showing the arrangement relationship between an object to be measured and a detector, etc. in an embodiment of the present invention. In the figure, P is the object to be measured, a welded pipe (hereinafter simply referred to as a pipe), and L is a pipe. A slit light source installed above P, D an image detector consisting of a group of two-dimensionally arranged photoelectric conversion elements installed obliquely above the irradiated part of the tube P, and T a welding device oriented toward the vicinity of the irradiated part. It is a position detector.

The pipe P is placed on a transport table (not shown) and is transported in the pipe axial direction with the weld W directly above. In the figure, C is a light section line illuminated by the slit light, and an image detector detects an image of this light section line C. Note that the positional relationship between the nine light sources and the image detector shown in the figure is an example, and the arrangement is not limited to the illustrated arrangement.

FIGS. 2(a) and 2(b) are diagrams for explaining the method of detecting a photocutting image by an image detector. In FIG. Indicates the center line, DI * 02 r D5 z '''r Dn+ is a linear array consisting of a large number (m) of microscopic photoelectric conversion element groups, and the detector is composed of n linear arrays. The detector has microphotoelectric conversion elements arranged in m rows and n
Needless to say, an area array in which a large number of arrays are arranged in a row may also be used. Light cutting illuminated by slit light @C
is the photoelectric conversion surface (
m
Detected as . In addition, the part indicated by the dotted line in the optically sectioned image of FIG. 2(b) shows the image of the bead cut portion when detection is performed after cutting the weld bead.

FIG. 3 is a diagram illustrating a welded portion step. In this figure, for convenience, the tubular structure before welding is shown as a blank pipe p in place of the pipe P in Figure 1. ) is the welding step after welding. Therefore, the welded part level difference refers to the level difference at both ends of the raw pipe before welding, indicated by Wo in the figure. However, since it is not possible to directly measure the amount of step WO online after welding, in actual operation, a method for indirectly determining step WO is used as described in the above-mentioned Japanese Patent Application Laid-Open No. 173801/1983. There is. The present invention also uses an indirect method to
It measures O. As is clear from Fig. 3, this level difference Wo is the difference in height between the outer peripheral surfaces of the pipe at the center of the weld when the heights of the outer peripheral surfaces of the pipe on both sides of the weld are extended toward the center of the weld. The level difference Wo can be calculated by detecting the distance between each point of the optically sectioned image shown in FIG. 2(b) and the reference position and processing the distance. At this time, since a certain range including the center position of the weld (the range of Wr shown in Fig. 2 (b), which corresponds to the welding bead part or the bead cutting part) has a shape different from the outer circumferential surface of the pipe. , it is necessary to exclude it from the detected values. Therefore, in the present invention, the first
As shown in the figure, a welding position detector T for detecting the center position of the welding part is separately installed to detect the center position of the welding part in the vicinity of the irradiated part. Various methods can be used as welding position detectors, such as temperature distribution measurement, surface gloss comparison, and electromagnetic methods. For example, Japanese Patent Application Publication No. 59
It is possible to use a temperature distribution measuring detector as described in Japanese Patent No. 197856. The exclusion range Wr can be predetermined according to the size of the pipe and welding conditions, so once the welding center position is detected, optical cutting corresponding to a predetermined length on both sides from the center position is performed. Excluding the separation distance detection value corresponding to a certain range Wr part on the image,
Equations representing the extravascular surface globules on both sides are calculated from the remaining separation distance detection values on both sides.

Now, as shown in FIG. 2(b), coordinate axes X and Y are set for the optically sectioned image Pr, and the point corresponding to the detected weld center position is set as X=O, and the photoelectric conversion of the image detector When a row (for example, row 1) of an element is set to Y=0 (reference position), the xy coordinates of each point (photoelectric conversion element) of the optically sectioned image Pr are determined.

In the X-Y coordinates, the X axis corresponds to the horizontal axis of the tube cross section, and the Y axis corresponds to the vertical axis. Therefore, the Y coordinate (distance from the reference position, and in the case of this example, also the count number of the photoelectric conversion element) of each point in the X-axis direction of the optically sectioned image Pr is from the reference position of each point on the outer peripheral surface of the tube. The series of distances between these points represents the profile of the outer circumferential surface of the tube. Of the X-Y coordinates of each of these points, the x
When the equation % (1) is obtained from the -y coordinate, this becomes an equation representing the profile of the outer circumferential surface of the pipe P on both sides of the welded part.

As mentioned above, the weld level difference is the level difference at the butt position of the raw pipes, and since the butt position is X=O in the X-Y coordinates, the weld level difference W0 is W0 == k 1PrLO
) Pray) l + c ”・＜3)k+c:
It can be determined as a constant.

In addition, in the actual pipe manufacturing process, the center of the weld may not be directly above the pipe due to vibration or twist.
Based on the detection result of the welding part center position, the above-mentioned calculation is performed after performing the coordinate transformation of the x-y' coordinates.

(Effects of the Invention) As described above, the present invention uses an image detector consisting of a group of two-dimensionally arranged photoelectric conversion elements to obtain a photosection image of the welded part and its vicinity, and also uses an image detector consisting of a group of two-dimensionally arranged photoelectric conversion elements, and The center position of the weld, which serves as a reference for calculating the step of the weld from the distance detection value, is detected by a separately provided weld position detector.

Welded pipe steps are removed during the welded pipe manufacturing process.

Fast and accurate for on-line measurement 1
゜It is possible to easily measure the step of the weld, and also to cut the welding pitch:
It has an excellent practical effect in that it can be measured regardless of whether it is before or after.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the arrangement relationship of detectors, etc. in an embodiment of the present invention, and FIGS. Figure 3 shows
It is a figure explaining a welding part level difference. P: welded pipe, W: welded part, Pr: optical cutting image, L Nislit light source, D: image detector, T: welding position detector, p: raw pipe,
C: optical cutting line. j [Figure 1 C; Yokirikankan Figure 2 C) Figure 2 Cb)

Claims (1)

[Claims] To measure the welded part level difference of a welded pipe, a slit light is irradiated perpendicular to the pipe axis direction to the welded part of the object to be measured and the outer peripheral surface of its vicinity, and a two-dimensional photoelectric conversion device is installed above the irradiated part. Detecting a light sectioned image by an image detector consisting of a group of elements, detecting the separation distance between each point of the light section image and a reference position,
On the other hand, the welding position detector installed near the irradiated part detects the welding part center position, and the respective distance detection values on both sides excluding a certain range including the welding center position from the separation distance detection values are detected. A welded pipe characterized in that an equation representing the profile of the outer circumferential surface of the object to be measured on both sides of the weld is determined from the series, and a step difference in the weld is determined from the difference between the solutions of the equation at a position corresponding to the center position of the weld. Method for measuring weld level difference.