JPH06122077A - Welding removal method for spot welding - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an easy welding removal method using existing equipment without new equipment investment or modification. [Structure] When the spot gun of the spot welding robot becomes welded, the spot gun is repressurized, and then the robot rotates the spot gun around the electrode tip of the spot gun, and re-energizes during the rotation. To melt the spot gun and work to release the welding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for releasing a spot welding gun when it is welded to a material to be welded.

[0002]

2. Description of the Related Art In a spot welding line, an industrial robot 1 has a gun 12 for spot welding and pressurizes a work on a jig to perform welding. The gun 12 is configured to be openable and closable. The tip of the gun 12 has an electrode tip 7 attached to the tip of a shank 6 protruding from the cylinder 5, and the gun arm 10 has an electrode tip 8 attached to the tip of a shank 9. A plurality of workpieces W, for example, workpieces 3 and 4, stacked by one electrode are pressed by a cylinder 5 and a welding current is supplied from a transformer 11 during that time to perform spot welding (see FIG. 1. FIG. 1 is an embodiment of the present invention. However, this part is the same as the conventional). However, even if the welding is completed at the welding spot position, the electrode tip and the work W are welded at the welding spot position 30 as shown in FIG. 4, and the robot 1 cannot be moved. Therefore, in the conventional method, as shown in FIG. 4 (a), the gun 12 is provided with a limit switch 29 for opening confirmation, and it is confirmed whether or not the gun 12 is opened after welding. ) (C), the electrode tip is in a state of being welded to the work W, and the worker has stopped the line and peeled the welded portion using a tool. As another method, a method of observing the conduction between the gun 12 and the work W at the end of welding based on the welding phenomenon of FIG. 4D can be obtained. If the welding is conducted, it is determined that welding has occurred, and re-energized at least once. There is a method by which the welded state can be released (see, for example, JP-A-1-299784).

[0003]

However, the conventional method for peeling the work W and the electrode tip of the gun by re-energization depends on the damage condition of the electrode tip, the material and surface condition of the work W, the welding conditions and the like. On the contrary, there is a possibility that both of them may melt and promote welding. Therefore, it is an object of the present invention to provide an easy welding removal method by using existing equipment without particularly making new equipment investment or modification.

[0004]

In order to achieve the above-mentioned object, the present invention re-pressurizes the spot gun of the spot welding robot when the spot gun of the spot welding robot is in a welded state, and the robot later The spot gun is rotated around the electrode tip, and re-energization is applied during the rotation to melt the spot gun and the work.

[0005]

With the above-mentioned means, the gun is pressurized at the position where the welding occurs, and then the gun is rotated with both electrode tips vertically contacting the work W as fulcrums. By rotating the gun, a sufficiently large couple can be applied, so that the work and the electrode tip are separated. The rotation angle at this time does not need to be large and may be about 10 to 20 degrees at most. Further, the application of electric current during rotation is intended to accelerate the melting of the work and the electrode tip by Joule heat, which allows more reliable peeling.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments and drawings. FIG. 1 is a schematic view of the system of the present invention, FIG. 2 is an operation explanatory view of a gun for releasing welding, and FIG. 3 is an operation flow. In the description, the materials 3 and 4 to be welded are referred to as a work W. An openable and closable gun 12 for spot welding is attached to the tip of the wrist of the industrial robot 1. Gun 12 is gun arm 1
The electrode tip 8 is attached from the 0 side through the shank 9, and the electrode tip 7 is attached from the cylinder 5 side through the shank 6.
Is attached. The gun 12 is opened / closed by the cylinder 5, and the opening / closing is performed by the electromagnetic valve 2 containing an air source.
It is done by the operation of 6, and it is the pressure side air 2 of the secondary side.
5, the return side air 24 and the cylinder 5 are connected. The operation of the electromagnetic valve 26 is performed by the pressurization signal cable 18 output from the input / output unit 14 in the robot controller 13.
Done through. The welding current of the gun 12 is controlled by the welding timer 28, and the current is controlled by the welding timer 28.
It is sent from the secondary power cables 22 and 23 to the transformer 11 attached to the gun. Further, in order to detect the welding after the completion of welding, a contact detection unit 17 is provided in the robot controller 13 to detect the detection line 20 from the gun 12 and the jig 2.
The detection line 21 is connected to the detection unit. To describe ordinary spot welding, first, when the robot 1 arrives at an arbitrary hitting point position taught, the robot controller 13 drives the cylinder 5 to bring the electrode tip 7 of the pressure side shank 6 into contact with the work W, At the same time, the controller gives a start command to the input / output unit 27 in the welding timer 28 via the signal line 29, and the work W
Spot weld. The welding current and time are controlled by the welding timer. At the end of welding, the welding timer gives a completion signal to the robot controller 13. Immediately thereafter, the controller 13 opens the cylinder 5 to the original state. This completes the welding sequence, but at the end, the welding of the gun 12 and the work W is judged by the robot controller by the above-mentioned circuit for detecting welding.

Next, the process after the welding is confirmed will be described. As shown in FIG. 3, the position is stored in the robot internal processing unit 15 after the welding is detected and a required calculation is executed. In other words, gun pressurization, welding timer activation, gun rotation control,
Perform a series of processes such as releasing the gun. FIG. 2 shows the gun operation at the welding position. First, this position is stored in the internal processing unit 15, then the gun cylinder 5 is driven, and the electrode tip 7a at the position before welding is the work piece. It moves to the position of 7b which contacts W. After that, the gun arm 10 is rotated around the electrode tip 8 which is in vertical contact with the work W as a fulcrum. There are two rotation directions, clockwise and counterclockwise, as shown in FIGS. 2B and 2C. This is an example. (B) is an example using counterclockwise rotation, and the jig post 2a which is an interfering object is avoided by rotating from the position of the gun arm 10a to the position of 10b. Similarly, for (d), rotate the gun arm clockwise from 10a to 10
b Rotate to avoid the obstacle 2a. The rotation control here means that the control unit 16 causes the robot 1 to rotate in the positive direction at a specified speed and angle, that is, when the gun arm 10 is turned from 10a to 10b in the clockwise direction or the counterclockwise direction, it is instantly turned in the negative direction. To return to the original position of 10a, and since the posture is controlled during rotation, the gun is the work W
It keeps the hit angle against.

Further, during the pressurizing rotation, the robot controller 13 outputs an energization command to the welding timer 28, so that a welding current flows between the work W and the two electrode chips, and the Joule heat melts the welding current. It facilitates peeling due to rotation. The energization time is set shorter than the rotation time, and when the rotation is completed, the gun cylinder 5 is opened and the electrode tip is returned to the position from 7b to 7a. The energization conditions used during this release are the work W
It may be arbitrarily determined depending on the material, surface condition, and other various conditions, but the current is lower than the conditions normally given to the work W, and there is no problem in short-time energization. This series of procedures can be repeated N times, but since the gun can be rotated at the welded position to give a large couple of force,
Usually, it can be canceled sufficiently by one operation. Further, the type of gun is not limited to the C type gun as shown in FIG. 2, but can be similarly applied to the X type gun.

[0009]

As described above, according to the present invention, after pressurizing the gun at the position where the welding occurs, the gun is mounted with the two electrode tips vertically contacting the work W as fulcrums. Rotate. By rotating the gun, a sufficiently large couple can be applied, so that the work and the electrode tip are separated. Further, since the energization during rotation takes into consideration that the work and the electrode tip are melted by Joule heat, it is more surely released. This is more efficient than the case where the worker stops the line and performs the peeling work. Moreover, the spot gun and its peripherals actually used can be conventional ones, and no investment is required for facility modification.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a system of the present invention.

FIG. 2 is an operation example of a gun for releasing welding, (a) is a perspective view before rotation, and (b) and (c) are front views showing a rotating state.

FIG. 3 is a diagram showing an operation flow for releasing welding.

FIG. 4 schematically illustrates a conventional welding phenomenon. (A) is a side view in which a normal welding operation is performed, (b) is a side view in which a work and an upper electrode tip are welded, and (c) is FIG. 3 is a side view in which the work is welded to the upper and lower electrode tips, and (d) is a side view in which the work is welded to the lower electrode tip.

[Explanation of symbols]

1 ... Robot, 2 ... Jig, 3, 4 ... Work W, 5 ... Cylinder, 7 ... Upper electrode tip, 8 ... Lower electrode tip, 1
0 ... Gun arm, 12 ... Gun, 13 ... Robot controller, 15 ... Internal processing unit, 17 ... Contact detection unit, 26 ... Electromagnetic valve, 28 ... Welding timer.

Claims (2)

[Claims] 1. When the spot gun of the spot welding robot is in a welded state, the spot gun is repressurized,
A method for releasing welding of spot welding, characterized in that the robot later rotates the spot gun around the electrode tip of the spot gun, and re-energizes during the rotation to melt the spot gun and the work. 2. The method of dewelding spot welding according to claim 1, wherein the spot gun is rotated in a direction in which there is no obstacle.