JPH05261557A - Device for deciding whether can body is welded adequately or not - Google Patents

Abstract

(57) [Summary] [Purpose] By obtaining welding information by image processing of the welded portion of the can body, the accuracy and speed of the welding suitability determination are improved. [Structure] An image pickup section 16 for picking up an image of a side seam portion of a can body, and an edge detection section 20 for detecting a boundary line between a welded section and a metal body of a can body from an image obtained by the image pickup section 16.
A reference line calculation unit 22 or 24 for calculating a reference line that smoothly connects the points forming the boundary line, and the reference line,
Comparison is made between each point that constitutes the actual boundary line, and a comparison unit 26 that detects the difference and whether or not the difference is greater than or equal to a predetermined value are determined. If the difference is greater than or equal to the predetermined value, the can is welded. A can body welding suitability determination device including a determination unit 28 that determines a defect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a can body welding suitability judging device, and more particularly to improvement of a welding information detecting mechanism.

[0002]

2. Description of the Related Art A method for manufacturing a can barrel by rounding a metal piece cut into a predetermined size to form a hollow cylinder, and welding the side surface overlapped portion of the hollow cylinder by electric resistance stitching is well known (Japanese Patent Laid-Open No. HEI-2). -165772). By the way, the overlapped portion of the can body that has been welded by electric resistance stitching may cause welding failure due to, for example, a splash (splash of molten metal) being caught between the welding electrodes. Is required. Conventionally used can body welding suitability determination method utilizes the fact that the welding state and welding current have a correlation, and uses the welding current change as an index for determination, or the temperature of the welded portion is closely related to the welding state. By utilizing the relationship, the temperature near the welding point during welding is measured using an infrared temperature sensor, and the temperature distribution at that point is used as an index for judgment (see Japanese Patent Laid-Open No. 63-212076), etc. There is.

[0003]

However, in any of the conventional can body welding suitability determination methods described above, since current detection or temperature detection must be performed during welding, the welding speed directly affects the accuracy of welding suitability determination. There is a limit to increasing the welding speed to improve the production efficiency, and the change in the welding speed may lead to a judgment error. Furthermore, changes in welding current or changes in temperature merely indirectly indicate the welding state, and there has been a demand for a more direct and accurate method of determining whether the welding state is appropriate. The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a can body welding suitability determination device capable of appropriately performing welding suitability determination regardless of changes in welding speed.

[0004]

The can body welding suitability judging device of the present invention is characterized by comprising an image pickup section, an edge detecting section, a reference line calculating section, a comparing section and a judging section. The imaging unit captures an image of the side seam portion of the can body, and the edge detection unit detects the boundary line between the welded portion and the can body metal portion from the image obtained by the imaging unit. . The reference line calculation unit calculates a reference line that smoothly connects the points forming the boundary line, and the comparison unit compares the reference line with each point forming the actual boundary line and detects the difference. . The determination unit determines whether or not the difference is equal to or greater than a predetermined value, and when the difference is equal to or greater than the predetermined value, determines that the can is defective in welding.

[0005]

According to the can body welding suitability judging device of the present invention, the boundary line between the welded portion of the side seam portion and the can body metal portion is substantially linear when the welding is properly performed. The suitability of the welding state is determined by directly observing the welded portion. That is, in the present invention, since the welding suitability is determined by performing the image analysis of the side seam portion of the can body, it is not necessary to interlock with the can body welding mechanism and the welding speed of the can is improved. In such cases, it is possible to always make a proper judgment as to whether or not the can body welding is appropriate.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a can body welding suitability determination device according to an embodiment of the present invention. As shown in the figure, a can body welding suitability determination device 10 of the present embodiment is installed at a rear portion of a well-known can body welding device 12, and a side seamed can 1 is formed.
4 is sent to the can body welding suitability determination device 10 and the suitability of the can body welding is determined. Can body welding suitability determination device 1 of the present embodiment
0 is provided with an imaging unit or a comparison unit corresponding to each of the front half 14a and the rear half 14b of the inspected can 14.
Corresponding parts have substantially the same configuration, and therefore, in the drawing, a and b are added to the end of the reference numerals of the parts, one (a system) will be described, and the other will be omitted.
First, the side seam portion of the first half portion 14a of the can is determined by the image pickup unit 16a which is a video camera for photographing the side seam portion and the frame memory 18a which temporarily stores the image information photographed by the image pickup unit 16a. And an edge detection unit 20a for detecting a boundary line between the welded portion and the can body metal portion from the image information of the frame memory 18a, and an end reference line calculation for calculating a reference line from the output of the edge detection unit 20a This is performed by the section 22a and the central reference line calculation unit 24a, and the comparison unit 26a which compares the outputs of the reference line calculation units 22a and 24a with the actual boundary line and outputs the degree of polymerization. Then, the comparison part 26 corresponding to the side seam of the can rear part 14b.
The output of b and the output of the comparison part 26a are input to the determination part 28, and the adequacy of welding of a side seam part is determined.

The can body welding suitability determination device 10 of the present embodiment is configured as described above, and its operation will be described below.
First, when the welding can 14 enters the determination area of the can barrel welding suitability determination device 10, the imaging units 16a and 16b respectively image the front half 14a and the rear half 14b of the can 14 and determine the respective welding states. By separately evaluating the first half 14a and the second half 14b of the can in this way, the processing speed can be greatly improved. Here, the image information captured by the image capturing unit 16 is temporarily stored in the frame memory 1
No. 8, which is stored in FIG. 8 and identifies the metal part and the welded part of the can 14 based on the light and shade information of the image, and detects the boundary line between both parts.
That is, FIG. 2A shows the side seam surface of the front end portion of the can body, and the bare metal portion 30 and the welded portion 32 of the can 14 have a difference in appearance. Therefore, the boundary line 3 between these parts 30 and 32
4, 36 are detected by image analysis.

The boundary lines 34 and 36 are divided into an end portion and a central portion of the can and sent to the end reference line calculating unit 22 and the center reference line calculating unit 24, respectively. That is, as shown in FIG. 2A, there is a welding start point (or welding end point) at the end of the can, and the inclinations of the boundary lines 34 and 36 are often large. On the other hand, in the central portion of the can 14, welding is performed stably, so that the boundary lines 34 and 36 are substantially parallel lines as shown in FIG. 3A. Therefore, if the same reference line is calculated at the center and the end of the can, it may not be possible to properly determine whether or not the can body welding is appropriate. Therefore, the reference lines should be calculated separately for both parts. In this embodiment, the end reference line calculation unit 22 and the central reference line calculation unit 24 calculate the reference straight line by the least square method. That is, at the end of the can, reference lines 38 and 40 having an inclination as shown by the solid line in FIG. 2B are formed, and at the center part, there are substantially parallel reference lines 38 and 40 as shown by the solid line in FIG. 3B. Become. Then, the end reference line and the center reference line are respectively input to the comparison unit 26, and the information on the actual boundary line from the edge detection unit 20 is compared with the reference lines 38 and 40. Here, the boundary line (collection of points) of the part B of the alternate long and short dash line of FIG. 2A is enlarged and the reference line is superimposed and shown in FIG. 2B, and the boundary line of the part B of the alternate long and short dash line of FIG. 3A is shown. The (collection of points) is enlarged and the reference line is superimposed and shown in FIG. 3B.

The suitability of the welding state is determined based on the amount of deviation between the reference line and the edge point indicating the boundary line. At this time, as the parameters used, the number of abnormal points in which the distance from the reference line to each actual edge point deviates by a predetermined value or more, the deviation value of the distance between the reference straight line and each edge point, the angle difference between the left and right reference lines, Alternatively, the next value NG (when the NG exceeds a predetermined value is determined to be defective) or the like can be used. NG = [Σ | p (y) -f (y) |] / n p (y): x position of the edge point at a certain y position f (y): at a certain y position of the straight line obtained by the least squares method Then, the determination unit 28 determines whether or not the can is welded based on the parameters.

As described above, the can body welding adequacy determining device 10 of this embodiment can directly grasp the welding state by image processing, and the image processing of the first half and the second half of the can is performed separately. By doing so, extremely high-speed determination can be performed. Further, by setting separate reference lines for the end portion and the central portion of the can, it is possible to accurately determine whether the welding is appropriate. In the present embodiment, when performing edge detection for detecting the boundary line between the welded portion and the metal barrel portion of the can, it is necessary to first detect the position of the side seam portion. In this case, it is preferable to detect the side seam portion by image analysis as in the case of performing the edge detection. Further, in the present embodiment, the image pickup unit 16a and the image pickup unit 16b are installed so as to correspond to the front half and the rear half of the can, respectively, in order to improve the efficiency of processing, but the present invention is not limited to this, and for example, the image pickup unit may be Only one unit or three or more units may be installed. Furthermore, in the present embodiment, the reference line is a straight line obtained by the method of least squares, but it is also possible to use an approximate curve by statistical processing.

[0011]

According to the can body welding suitability judging device of the present invention, since welding information is obtained by image processing of a can body welding portion, it is possible to make the judgment accurate and speed up.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a can body welding suitability determination device of the present invention.

2 is an explanatory view of a discrimination mechanism of a front half of the can in the apparatus of FIG.

FIG. 3 is an explanatory view of a discrimination mechanism of a rear half of the can in the apparatus of FIG.

[Explanation of symbols]

 10 Can Body Welding Suitability Judgment Device 14 Inspected Can 16 Video Camera (Imaging Section) 20 Edge Detection Section 22, 24 Reference Line Calculation Section 26 Comparison Section 28 Judgment Section

Claims (1)

[Claims] 1. An image pickup unit for taking an image of a side seam portion of a can body, an edge detection unit for detecting a boundary line between a welded portion and a metal barrel of a can body from an image obtained by the image pickup unit, A reference line calculation unit that calculates a reference line that smoothly connects each point that forms the boundary line, a comparison unit that compares the reference line and each point that forms the actual boundary line and detects the difference, and the difference Is a predetermined value or more, and if it is a predetermined value or more, a determination unit that determines that the can is defective in welding is provided.