JPH0367792B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention detects a welding line as a visual sensor for a device that automates arc welding, such as an arc welding robot or a special machine, and provides positional information of the welding line to the automatic machine. It is related to the device.

Traditionally, in order to automate arc welding,
Automatic detection of weld lines was one of the major challenges.

Weld line detection device (hereinafter referred to as weld line sensor)
There are two main types: contact type and non-contact type.

Contact-type welding line sensors are located in front of the welding torch and search the vicinity of the welding line, but they have problems with wear and heat resistance and dust resistance of the sensor tip, as well as insulation from large currents and poor response. Practical limitations are imposed due to lack of such features.

On the other hand, non-contact weld line sensors can be classified in principle into electromagnetic types, capacitance types, back pressure types, optical types, etc. Weld line sensors that use electromagnetic or capacitive types have a short distance from the workpiece to the sensor head (20 mm or less) and a large sensor head diameter, resulting in poor resolution, which limits their practical use. Back pressure type weld line sensors have problems with clogging due to welding spatter and reliability of the nozzle, and are far from practical use. A typical method for optically detecting a weld line is one using a slit light and an imaging device, as shown in FIG. This device consists of a workpiece 1 having a V-shaped groove,
1' is irradiated with a slit-shaped light 3 from a floodlight 2,
The groove shape image of the slit light is captured by the imaging device 4, and through image processing, as shown in FIG. 6a is determined as the distance x from the edge of the field of view 5.
Further, the positional relationship between the optical parts 2 and 4 and the welding torch is such that the optical parts 2 and 4 are located several centimeters in front of the welding torch, and forward sensing is performed. A welding line sensor using this slit light must irradiate the slit light 3 at a substantially right angle to the welding line 6, and has so-called directionality. Therefore, the application is limited to objects to be welded that have a straight welding line, and the welding posture is also limited. Furthermore, since the optical parts 2 and 4 are located in front of the welding torch, it is impossible to apply this method when there is a wall in front of the welding torch or to three-dimensional (three-dimensional) objects to be welded, such as boxes.

As described above, in the past, there were many practical limitations, and the application was limited to some specific objects to be welded.

The present invention is a weld line detection device that eliminates the above-mentioned conventional drawbacks, makes it possible to detect weld lines on various objects to be welded, and greatly alleviates restrictions on welding postures.

Examples of the present invention will be shown below, and the effects thereof will be explained using FIGS. 3 to 6.

As shown in FIG. 3, the configuration of this embodiment includes a light projecting section that emits an annular light 9 having a predetermined line width w and a diameter D that sufficiently covers the weld line portion 8 of the workpieces 7 and 7'. 1
0, and an imaging section 11 that images the annular light 9 on the workpieces 7 and 7'. The welding torch 12 is fixed so that the welding wire 13 intersects at the tip P, and the light projecting section 10 and the imaging section 11 are housed in a case 14, and the case 14 is connected to the welding robot hand 16 via a flange 17 by a fixed shaft 15. installed. On the other hand, the welding torch 12 is moved by a torch slider 1 that retracts the welding torch 12 in the direction of the arrow via a torch fixing jig 18.
9 and is connected to a fixed shaft 15 by a fixed rod 20, and the welding torch 12 and optical parts 10, 11 are integrated.

Next, the operation of this device will be explained. Light projector 1
The annular light 9 generated from the welding object 7, 7' is irradiated near the joint of the objects to be welded 7, 7', and the annular light 9 is imaged by the imaging section 11. Through image processing, the image within the field of view 21 of the imaging section shown in FIG. The coordinates (x ₁ , y ₁ ) of the welding point 8a and the coordinates (x 2 , y 1 ) of the welding point _8b from the annular light image 9a are
_y2 ) and correct the welding robot's teach data. Sensing is performed at high speed only at several locations on the object to be welded, that is, at the robot's teach point, and after correcting the teach data, welding is started. During sensing, the welding torch 12 is retracted by the torch slider 19 in the direction of the arrow A out of the field of view of the imaging section, thereby preventing the welding torch 12 from interfering with sensing.

FIG. 6 shows the annular light irradiation patterns at various joints. A is a lap joint, B is a V-groove, and C is a fillet.

Next, we will discuss the effects of this device.

Since the extension lines of the central axes of the light projecting section 10 and the imaging section 11 intersect at the welding wire tip P, that is, at the welding position, the direction of movement of the welding torch 12 has a degree of freedom of front, rear, left, and right, that is, 360 degrees. It is not related to barriers in the traveling direction, and can be applied to objects to be welded such as three-dimensional objects, such as boxes. Furthermore, since the irradiated light is annular, it has no directionality, and sensing is possible from all angles, and sensing is also possible not only at corners and large curvature areas, but also at small curvature areas.

As described above, the welding line detection device of the present invention is widely applicable to various objects to be welded, and enables welding line detection without restrictions on welding posture and direction. The value is great.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining a conventional weld line detection method, Fig. 2 is a view within the field of view of an imaging device when the method is implemented, and Fig. 3 is a weld line obtained by the weld line detection device of the present invention. Diagram to explain the detection method,
FIG. 4 is a front view of an embodiment of the weld line detection device of the present invention, and FIG. 5 is a view within the field of view of the imaging unit when implementing the weld line detection method based on the device of the present invention.
6A, B, and C are diagrams showing irradiation patterns of annular light on various objects to be welded. 7, 7'... Work to be welded, 8... Welding line portion, 9...
...Annular light, 10...Light projecting section, 11...Imaging section,
12...Welding torch, 13...Welding wire, 18
...Torch fixing jig, 19...Torch slider,
20...Fixed rod.

Claims (1)

[Scope of Claims] 1. A light projection unit that emits annular light having a predetermined line width and a diameter that sufficiently encompasses the weld line, and an imaging unit that images the annular light on the workpiece. The welding line detection device is characterized in that the light projecting section and the imaging section are fixed near a welding torch such that extension lines of their respective central axes intersect at a welding wire tip position of the welding torch. 2. The welding line detection device according to claim 1, further comprising means for retracting the welding torch out of the field of view of the imaging unit when detecting the welding line.