JPH01182704A - Weld line detecting apparatus - Google Patents

Abstract

PURPOSE:To recognize the position of the end surface of a lap joint and to detect a weld line, by projecting light having approximately uniform illuminance from an angle, at which the end surface of the lap joint can be viewed, and arranging a light receiving camera with respect to the reflected light. CONSTITUTION:Slit light is projected from a slit lighting device 5 on a lap joint shaped welding work 1. Spot light is projected on the work 1 from a spot lighting device 4 so that illuminance becomes approximately uniform. The parts, on which the light beams are projected, are picked up with a television camera 6 and displayed on a screen 11. On this screen 11, only an image 13 of the slit light and the image of the end surface 2 of the lap joint are lighting intensely. Such a state is obtained. When the starting point of welding is instructed, at first the center of gravity of the end surface 2 is obtained within center-of-gravity measuring ranges 14, and the center of gravity of the slit light is obtained within center-of-gravity measuring ranges 15. At the time of the operation to the starting point of welding, the centers of gravity are obtained by the same way. When the centers of gravity are made different because of dispersion and the like in the shape of the welding work 1, the difference in the centers of gravity at the time of instruction and at the time of operation is converted into the coordinates of a robot (the direction of a welding torch 7 and the up and down directions perpendicular to the direction of the torch).

Description

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

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 when determining the position of a weld line in a lap joint shape, as shown in the optical cutting method, which irradiates two slit lights and determines the positional relationship from an image distorted by the shape unique to the welding workpiece. The photoablation method was also used.

Problems to be Solved by the Invention When the conventional optical cutting method is used for a lap joint-shaped workpiece,
Unless the light reflectance of the welding object is low, secondary reflection occurs near the position where the slit light is distorted by the unique shape of the welding work, so an image processing device separates the slit light image and the secondary reflection image of the slit light. It was difficult to identify.

Means for Solving the Problems In order to solve the above problems, the weld line detection device of the present invention includes:
A light irradiation section that irradiates the object to be welded with substantially uniform illuminance light, a slit light irradiation section that irradiates the object to be welded with slit light, a light receiving section that receives an image of the substantially uniform illuminance light and the slit light, and a light receiving section. and an image processing device that determines the position of the welding line from the position of the image received by the light.

Effect: In the above means, approximately - heat-collecting light is emitted from an angle at which the end face of one overlap joint can be seen with respect to the welding line of the overlap joint shape, and a light receiving camera is placed at an angle where the reflected light from the end face of the overlap joint is strong. Once placed, the position of the end face of the lap joint can be recognized. This allows the weld line to be detected.

Furthermore, even if the light reflectance of the welded object is not low,
By accurately recognizing the position of the welding line and shifting the robot by the amount of deviation from the teaching, welding can be performed on the welding line even if the position of the workpiece is different from the teaching position as long as it is within the detection range.

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 an illuminator, a television camera for receiving light, 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, 6 is a slit illuminator, 6 is a television camera for receiving light, and 7 is a welding torch.

First, as shown in Fig. 1, a welding workpiece 1 in the shape of a lap joint is irradiated with slit light from the slit illuminator 6 and spot light from the spot illuminator 4 so that the illuminance is almost uniform. When the irradiation section is projected at step 6, a screen is obtained in which only the slit light image and the end face 2 of the overlapping joint shape shine strongly, as shown in FIG.

In Figure 2, 11 is the screen shown by the television camera, 1
Reference numeral 2 denotes a portion strongly illuminated by the spotlight, 13 an image of the slit light, 14 a range for measuring the center of gravity of the image by the spot light, and 16 a range for measuring the center of gravity of the f-elephant of the slit light. The position of the weld line can be recognized by determining the center of gravity of the image of this slit light and the image of the reflected light from the end face of the overlapping joint shape using an image processing device.

However, if the spot illuminator 5 or the television camera 6 is set above or in front of the end surface 2 of the overlapped joint shape, the reflected light from the end surface 2 cannot be received.

The welding line cannot be recognized, and if it is set near the welding torch 7 as shown in FIG. 1, it will be in the shadow of the welding torch 7, so it is necessary to shift the welding torch 7 backwards during sensing.

FIG. 3 shows a flowchart 1 in which the robot corrects the welding starting point position in the direction of the welding torch and in the vertical direction perpendicular to the welding torch 7. First, when teaching the welding starting point, the second
As shown in the figure, the center of gravity of the end face 2 of the lap joint shape that shines strongly is determined in the center of gravity measurement range 14, and the center of gravity of the slit light is determined in the center of gravity measurement range 15. 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 positions of the centers of gravity will not change, but they will differ somewhat due to variations in the shape of the welding workpiece 1, variations in the position of the workpiece fixing jig, etc. This difference in the center of gravity during teaching and during operation is converted into robot coordinates (the direction of the welding torch and the vertical direction perpendicular to the welding torch).

The position correction amount in the direction of the welding torch is X, the position correction amount in the vertical direction perpendicular to the welding torch is Y, the difference in the center of gravity of the slit light image during teaching and during operation iDX, the difference in the center of gravity of the spot light image -
If it is 1DY, the relationship will be a linear equation.

X=A*DX+B*DY Y20*DX-)-D*DY Here, M, B, C, and D are coefficients that are determined by the positions of the illuminator 4°6 and the camera 6, and are determined by experiment.

If the robot position 'iX, :Y is corrected, the positional relationship between the welding position and the workpiece will be the same as that at the time of 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 can be performed with the same positional relationship.

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 positions of the five end faces of the lap joint can be recognized, and thereby the weld line can be detected.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a weld line detection device showing an embodiment of the present invention, Fig. 2 is a view showing an image observed by the camera of the device, and Fig. 3 is a weld line detection process using the same device. It is a flowchart. 1...Welding workpiece, 2...End face of lap joint, 4...Spot illuminator, 6...
Slit illuminator, 6...TV camera. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] a light irradiation unit that irradiates a lap joint-shaped workpiece with substantially uniform illuminance light of substantially uniform illuminance; a slit light irradiation unit that irradiates the workpiece with slit light; and a light irradiation unit that irradiates the workpiece with substantially uniform illuminance. comprising a light receiving unit that receives an image of the slit light, and an image processing device that determines the position of the welding line from the position of the image received by the light receiving unit,
A welding line detection device characterized in that the position of a welding line in a lap joint shape is detected from the positions of both a cross-sectional image of the lap joint formed by the substantially uniform illuminance light and an image of the slit light.