JPH01184403A - Weld line detecting device - Google Patents

Abstract

PURPOSE:To detect a weld line by recognizing an end face position of a lap joint by radiating light beams to the weld line of a lap joint shape and measuring its reflected lights. CONSTITUTION:From a spot illuminator 4, spot light beams are radiated to a weld work 1 of a lap joint shape, and its reflected light beams are brought to image pickup by a television camera 5. In such a way, a part 12 where only an end face 2 of a lap joint shape is intensely bright is reflected on a television screen 11. In a center-of-gravity measuring range 13, by deriving the center of gravity of an image of the reflected light beams of the end face 2 by an image processor, a position of a weld line can be recognized.

Description

[Detailed Description of the Invention] Industrial Application Field Welding that detects and recognizes the weld line of a lap joint-shaped object to be welded using a sensor, and automatically corrects the difference in position from the position taught to the welding robot. This invention relates to a welding line detection device for a copying robot.

Conventional technology Conventionally, the method of determining the shape or position of the workpiece is as follows:
For example, it is a well-known fact that the position of the weld line of a lap joint shape is determined by the optical cutting method, which uses two slit lights to determine the positional relationship from an image distorted by the shape unique to the welding workpiece. Time too.

A photosection method was used.

Problems to be Solved by the Invention When the conventional optical cutting method is used for a lap joint-shaped workpiece,
When the workpiece is thin (approximately 1.5 mm or less), the slit light is hardly distorted by the workpiece.
It has been difficult to accurately determine the position of a weld line in a lap joint shape using an image processing device.

Means for Solving the Problems In order to solve the above problems, the weld line detection device of the present invention includes:
Equipped with a light irradiation unit that irradiates light onto the workpiece, a light reception unit that receives the image of the irradiation light, and an image processing device that determines the position of the weld line from the position of the image of the lap joint of the workpiece that the light reception unit receives. The light irradiated from the irradiation part is directed toward the end face of the overlap joint and is irradiated almost uniformly within the required field of view, so that different images from the end face of the overlap joint and the other workpiece surfaces can be distinguished. It is something to do.

Effect: In the above means, light with uniform illuminance is emitted to the weld line of the lap joint shape from an angle where the end face of the lap joint can be seen, and the light is received at an angle where the reflected light by the end face of the lap joint is strong. When you place the camera.

The position of the end face of a lap joint can be recognized. This allows the weld line to be detected.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a diagram showing the positional relationship between a spot illuminator for light irradiation, a television camera for light reception, and a welding workpiece.

In Fig. 1, 1 is a welding workpiece having a lap joint shape, 2 is an end face of a lap joint shape, 3 is an arm of a welding robot, and 4 is a welding workpiece having a lap joint shape.
6 is a spot illuminator for irradiating light, 6 is a television camera for receiving light, and 6 is a welding torch.

First, as shown in FIG. 1, spot light is irradiated from the spot illuminator 4 onto the welding workpiece 1 in the shape of a lap joint so that the illuminance is almost uniform, and when the irradiated part is imaged with the television camera 6, the second As shown in the figure, a screen is obtained in which only the end face 2 of the lap joint shape shines strongly. In FIG. 2, 11 is the screen shown by the television camera, 12 is the strongly shining part, and 13 is the center of gravity measurement range.

The position of the weld line can be recognized by determining the center of gravity of the image of the reflected light from the end face 2 of the lap joint shape using an image processing device.

However, if the spot illuminator 4 or television camera 6 is set above or in front of the end face 2 of the lap joint shape, it will not be able to receive the reflected light from the end face 2, making it impossible to recognize the weld line, and as shown in Figure 1. If it is set near the welding torch 6, it will be in the shadow of the welding torch 6, so it is necessary to shift the welding torch 6 to the rear during sensing.

FIG. 3 shows a flowchart for correcting the welding start point position in the vertical direction perpendicular to the camera viewing direction using the robot.

First, when teaching the welding start point, the center of gravity of the end face 2 of the lap joint shape that is shining strongly as shown in Fig. 2 is measured in the center of gravity measurement range 1.
Find it in 3. Next, the center of gravity is similarly determined when driving to the welding start point. If the welding workpiece 1 is at the same position during teaching and operation, the position of the center of gravity will not change, but it will differ somewhat due to variations in the shape of the welding workpiece 1, variations in the position of the workpiece fixing jig, etc. When this difference in the center of gravity between teaching and operation is converted into robot coordinates and the position of the robot is shifted, the positional relationship between the welding position and the workpiece 1 becomes the same as that during teaching. When welding is started, even if the position of the welding workpiece 1 is different within the detection range during teaching and during operation, welding is completed with the same positional relationship.

However, although this method alone cannot detect the amount by which the welding workpiece 1 has shifted in the camera viewing direction, since the camera viewing direction is close to the direction in which the torch penetrates, even if the welding workpiece 1 moves somewhat, it often does not affect the welding.

If the welding work 1 shifts significantly in this direction, affecting the welding, it is necessary to use a light cutting method using a single slit light or the like to detect it.

The position during welding can be detected by performing the above-described welding start point detection method at regular intervals or at regular moving distances, but in the case of arc welding, it is necessary to distinguish between arc light and light reflected by an illuminator.

Effects of the Invention As described above, according to the present invention, the position of the end face of a lap joint can be detected, and thereby the weld line can be detected. In addition, even for lap joint shapes where the thickness of the workpiece is thin, the position of the weld line is accurately recognized, and the robot is shifted by the amount of deviation from the teaching, so that the workpiece can be welded if it is within the detection range. Welding can be performed on the welding line even if the position of the welding line is different from that at the time of teaching.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a welding line detection device showing an embodiment of the present invention, Fig. 2 is a diagram showing an image obtained by a television camera of the same device, and Fig. 3 is a welding line detection process using the same device. It is a flowchart which shows. 1... Welding work with lap joint shape, 2...
...End face of overlapped joint shape, 4...Spot illuminator, 6...TV camera for light reception. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3

Claims (1)

[Claims] A light irradiation unit that irradiates light onto the workpiece, a light reception unit that receives an image of the irradiation light, and image processing that determines the position of the weld line from the position of the image of the lap joint end face of the workpiece that the light reception unit receives. comprising a device, which irradiates the light irradiated from the irradiation part almost uniformly in the range of the required field of view toward the end face of the lap joint;
A welding line detection device characterized by identifying different images from the end face of the lap joint and the other workpiece surfaces.