JPH0694640A - Checking method of quality of welding - Google Patents

Abstract

PURPOSE:To obtain a checking method of the quality of welding which makes it possible to obtain a correct linear image of a light-cut plane and also to determine the quality from the linear image. CONSTITUTION:A slit light is applied to a welded part after the completion of an arc welding process, by using a robot different from a robot conducting arc welding, and a lightcutting image is obtained by a reflected light thereof. The quality of welding is judged from the logical product or the majority of determination of any one of an area 26 formed by a linear image of the slit light in a region specified beforehand, positions 24 of bending points of the linear image of the slit light, a length 25 of a segment between the bending points and the continuity 23 of the linear image of the slit light, or of determination of a plurality of them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting the welding quality of a welded part.

[0002]

2. Description of the Related Art In automatic welding using an industrial robot,
The problem is how to check the welding quality. In the past, the check was generally performed during welding and the information was fed back to the welding control. For this reason, a welding torch, a slit light irradiation unit, and an imaging unit are integrated in the wrist of the robot and processed in real time (for example, Japanese Patent Laid-Open No. 63-63).
No. 173102).

[0003]

However, although noise is removed in order to obtain a line drawing of the light cut surface of the welded portion during welding, it is difficult to remove the disturbance light due to the welding arc light, etc. It was not possible to obtain a line drawing of the light section. Also, since the welding torch and the image pickup device are integrated and follow the welding to image the surface of the welded portion during the welding operation, although it is possible to perform welding in the optimum posture for the welding torch, it is ideal for the image pickup device. It may not be possible to take an image in a proper posture, and an image of the light section may not be obtained accurately depending on the shape of the welded portion. An object of the present invention is to provide a welding quality inspection method capable of obtaining an accurate line drawing of a light section and determining the quality of the quality from the line drawing.

[0004]

SUMMARY OF THE INVENTION The present invention is a method for inspecting welding quality by irradiating an arc-welded portion with slit light to obtain a light-section image by the reflected light, wherein the light-section image is welded. The method is characterized in that it is obtained after the completion of the steps and is one of the following methods. The area formed by the line drawing of the slit light is obtained in a predetermined area, and if the area value does not fall within the predetermined range, it is determined that the quality is poor. The bending point of the line drawing of the slit light is searched, and if the position of the bending point does not fall within a predetermined range, it is determined that the quality is poor. The bending point of the line drawing of the slit light is searched, and if the length of the line segment between the bending points does not fall within a predetermined range, it is determined that the quality is poor. If the line drawing of the slit light is not continuous, it is determined that the quality is poor. The quality is judged by the logical product of at least two judgments or the majority decision in the inspection method described above. In addition, these inspections are characterized by being performed by a robot other than the arc welding robot.

[0005]

According to the present invention, it is possible to obtain a stable image and increase the inspection accuracy by performing only the check separately after the welding process, rather than capturing an image with a lot of noise during welding.
It is based on the knowledge that it will be efficient as a whole. That is, the present invention, since a stable image after completion of welding is obtained, either the area created by the line drawing, the position of the bending points, the length between the bending points, or the continuity of the line drawing, or a plurality of viewpoints thereof. From this, it is possible to judge the quality.

[0006]

EXAMPLES Specific examples will be described below. FIG. 1 shows an example of an apparatus for carrying out the present invention. 1 is a robot, 2 is a laser slit light emitting part, 3 is a CCD camera, 4 is a holding part, 5 is an object to be inspected (work), 6 is a welding bead part, and 100a. Is a line (light cut image) reflecting the outer shape of the weld bead portion 6. The robot 1 holds the laser slit light emitting unit 2 and the CCD camera 3 via the holding unit 4. Then, the CCD camera 3 is driven and controlled by a robot controller (not shown).
Can be imaged along the welding line, or any point can be imaged. Here, it should be noted that the welding torch is not held integrally as in the conventional case, so that the holding unit 4 is downsized and the robot 1 can easily control the attitude of the CCD camera 3. Now, the laser light generated by the laser light emitter (not shown) is sent to the light emitting unit 2 through the light guide of the glass fiber. The light emitting unit 2 is a slit lens, and slit laser light is emitted toward an object (welding bead portion). And this slit light is
A line (light cut image) reflecting the outer shape of the weld bead 6 as shown by 100a is formed on the weld bead 6 and the work 5. Then, the image is sent to the CCD camera 3. FIG. 2 is a processing flow of the present invention. Figure 2
For simplification, an example is shown in which one of four determination criteria is used for determination, but the determination may be made by a logical product of two or more determination results or a majority decision. By the way, since the light section image captured (21 in FIG. 2) has a certain width,
This is extracted as a line drawing by a known method (22). The present invention uses this line drawing data. If the welding quality is good, it appears as shown at 100b in FIG. Here, the portion A is the surface of the work, and the portion B corresponds to the outer shape of the bead portion. That is, if the welding quality is good, a continuous broken line image having the bending points b1 and b2 is obtained, the bending points b1 and b2 maintain a constant positional relationship, and the bending points b1 and b2 are maintained.
The length between the two becomes a substantially constant value. On the other hand, if there is a broken work piece or a blowhole,
When the continuity of the line drawing is interrupted and the core is misaligned during welding or the width of the bead is insufficient, the positional relationship between the bending points b1 and b2 and the length between the bending points b1 and b2 are within a predetermined range. Off. The following judgment is performed using the above properties. As shown in the line drawing 100c in FIG. 4, since the continuity of the line drawing is interrupted, it is possible to determine the defect (23). Further, as shown in the line drawing 100d of FIG. 5, the position of the bending point is b
Since it is changed from 1, b2 to d1 and d2, it is possible to judge the defect based on the change amount (24) of each position or the length between d1 and d2. Yes (2
5). Further, as shown in FIG. 6, regions c1 and c2 are designated in advance at positions corresponding to both sides of the bead,
Area s of the portion located on the left side of the line drawing 100e in the region
1 and s2 are calculated in advance, and the area in the region changes from s1 and s2 to s1 ′ and s2 ′ as shown in the line drawing 100f in FIG. It is possible to do (26). Further, a more reliable judgment can be made by making a judgment based on a plurality of logical products of these judgment results or a majority decision.

[0007]

As described above, according to the present invention,
By applying this method to the work after welding, it is possible to stably obtain a predetermined welding inspection result. This makes it possible to automate the welding quality inspection.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an apparatus for carrying out the present invention.

FIG. 2 is a flowchart of the present invention.

FIG. 3 is an explanatory diagram of a light section image.

FIG. 4 is an explanatory diagram of a light section image.

FIG. 5 is an explanatory diagram of a light section image.

FIG. 6 is an explanatory diagram of a light section image.

FIG. 7 is an explanatory diagram of a light section image.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Robot 2 Light emitting part 3 CCD camera 4 Holding part 5 Inspected object (work) 6 Weld bead part 100a Line reflecting the outer shape of the weld bead part 6 (light cut image) 100b to e Light cut image processed

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuyo Yoshida 2-1, Kurosaki Shiroishi, Hachimansai-ku, Kitakyushu, Fukuoka Prefecture Yasukawa Electric Co., Ltd.

Claims (6)

[Claims] 1. A method for inspecting welding quality by irradiating an arc-welded portion with slit light and obtaining a light cutting image by reflected light thereof, wherein the light cutting image is obtained after completion of the welding step, and A welding quality inspection method, characterized in that an area formed by a line drawing of slit light is obtained in a designated area, and if the value of the area does not fall within a predetermined range, it is judged that the quality is poor. 2. A method for inspecting welding quality by irradiating an arc welded portion with slit light and obtaining a light cutting image by the reflected light, wherein the light cutting image is obtained after the welding process is completed, and the slit is used. A welding quality inspection method, characterized in that a bending point of a line drawing of light is searched, and if each position of the bending point does not fall within a predetermined range, it is judged that the quality is poor. 3. A method of inspecting welding quality by irradiating an arc-welded portion with slit light and obtaining a light-section image by the reflected light, wherein the light-section image is obtained after completion of the welding step, and A welding quality inspection method, characterized in that a bending point of a line drawing of light is searched for, and if the length of the line segment between the bending points does not fall within a predetermined range, it is judged that the quality is poor. 4. A method for inspecting welding quality by irradiating an arc-welded portion with slit light and obtaining a light-section image by the reflected light, wherein the light-section image is obtained after completion of the welding step, and A welding quality inspection method, characterized in that when the line drawing of light is not continuous, it is judged as poor quality. 5. A method for inspecting welding quality by irradiating an arc-welded portion with slit light and obtaining a light cutting image by reflected light thereof, wherein the light cutting image is obtained after completion of a welding step, and A quality inspection method for welding according to any one of claims 1 to 4, wherein the quality is judged by a logical product or a majority decision of at least two judgments. 6. A welding quality inspection method, wherein the inspection according to any one of claims 1 to 5 is performed by a robot different from a robot that performs arc welding.