JPH05305449A - Spot welding equipment for robot - Google Patents

Abstract

PURPOSE:To provide the spot welding equipment for the robot capable of performing spot welding without applying deformation pressurization on a work by providing a means capable of stopping the movement of the robot at the position where a fixed electrode is abutted on one side of the work. CONSTITUTION:A welding gun 2 is supported freely floatably for a robot arm 4 by a welding gun supporting member 3, the robot is moved to the jig position where a reference plane 24 to coincide with the clamping position of the work for each specified cycle of welding work is set up and a floating state of the welding gun 2 is fixed by a fixing means on the position when the fixed electrode 6 abuts on the reference plane 24. Since the abutting position of the fixed electrode 6 on the work in accordance with the degree of wear of the electrode is taught to the robot by this operation, even when the welding gun 2 is moved to the work to perform welding by the robot, the fixed electrode 6 abuts accurately on one side of the work, can stop its movement and spot welding which does not give the deformation pressurization to the work is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spot welding apparatus for a robot which is mounted on a robot to perform spot welding.

[0002]

2. Description of the Related Art When performing spot welding, when clamping a work between a fixed electrode and a movable electrode which are arranged opposite to each other, the center of clamping by both electrodes and the center of the work in the clamping direction do not coincide. At times, the work will be deformed. In order to prevent the work from being deformed due to such a difference in the center of the clamp, the welding gun is conventionally provided with an eco-raising device. In the spot welding apparatus shown in FIG. 4, the welding gun 31 has an eco-rising device 3
2 is attached to the robot arm 33 via the robot arm 33, and when the robot moves the welding gun 31 to the welding portion of the work 34, the fixed electrode 35 is attached to the work 34 as shown in FIG.
The movement of the robot arm 33 is stopped at a position separated by a required distance from the lower surface of the robot arm 33. From this state, the movable electrode 36
Is driven to move toward the fixed electrode 35 by the cylinder 37, and further moves forward even after the tip end thereof contacts the upper surface of the work 34. The welding gun 31 which receives the contact pressure of the work 34 against the movable electrode 36 is
Since it is floatingly supported by 2, the movable electrode 36 is pulled up upward in the drawing by advancing even after the movable electrode 36 hits the work 34, and the fixed electrode 35 is fixed to the work 34.
Abut the lower surface of. Here, the clamp center of both electrodes 35 and 36 and the clamp center of the work 34 coincide, and the work 34 is pinched by both electrodes 35 and 36 and energized to perform spot welding.

[0003]

As described above, in the conventional spot welding device, spot welding is performed by adjusting the difference in clamp position by the eco-raising device. In order to operate this eco-raising device, Pressurization proportional to the weight of the welding gun and the advancing speed of the movable electrode is applied to the work. When the movable electrode is advanced rapidly, this pressurization distorts the work and deforms it in a work of low strength. There was a problem that caused it. When moving the welding gun to the welding part of the workpiece by the robot,
The above problem can be solved if the welding gun can be stopped at the position where the fixed electrode is always in contact with one side of the work, but the robot wears the fixed electrode against the work because the electrode wears due to repeated welding. It is difficult to stop the welding gun at the position where it was made to move, and after stopping the movement at an appropriate interval as in the above-mentioned conventional example, since the movable electrode is advanced, the pressure applied to the work can be reduced to some extent. There wasn't. The present invention has been made in view of the conventional problems as described above, and by means that can stop the movement of the robot at the position where the fixed electrode is in contact with one surface of the work,
An object of the present invention is to provide a spot welding apparatus for a robot that can perform spot welding without applying deformation pressure to a work.

[0004]

In order to achieve the above object, the means adopted by the present invention is to fix the fixed electrode of a welding gun mounted on the tip of a robot arm after abutting it on one side of a workpiece. In a spot welding apparatus for a robot, in which a movable electrode, which is opposed to an electrode and is movably supported, advances in the direction of a work, and both sides of the work are sandwiched between the fixed electrode and the movable electrode to energize, the fixed electrode is the movable electrode. Spot welding apparatus for a robot, comprising: a welding gun support member that is floatable in the advancing direction of the robot and supported by the robot arm; and a fixing means that fixes the welding gun at an arbitrary floating position. Configured as.

[0005]

According to the present invention, the welding gun is supported by the welding gun support member so as to be floatable with respect to the robot arm and can be fixed at an appropriate position. Therefore, the clamping position of the work is fixed every predetermined cycle of welding work. The robot is moved to the jig position where the reference surface corresponding to the above is installed, and the welding gun is fixed by the fixing means at the position where the fixed electrode is brought into contact with the reference surface. Even if the electrode wears due to this operation, the robot always teaches the contact position of the fixed electrode to the work. Therefore, even when the robot moves the welding gun to the work to perform welding, the fixed electrode can be accurately measured. The movement can be stopped at the position where it abuts on one side of the work, and spot welding can be executed without applying deformation pressure to the work.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. still,
The following examples are examples of embodying the present invention and do not limit the technical scope of the present invention. Figure 1
2 is a side view showing a configuration of a robot spot welding apparatus according to an embodiment of the present invention, FIG. 2 is a plan view showing a configuration of a welding gun support member and fixing means, and FIG. 3 is a sectional view taken along the line AA of FIG. Is. In FIG. 1, a spot welding apparatus 1 for robots
The welding gun 2 is mounted on the robot arm 4 via the welding gun support member 3. The welding gun 2 drives the movable electrode 7 arranged at the position opposite to the fixed electrode 6 mounted on the tip of the gun arm 5 by the cylinder 8 so as to move the work between the fixed electrode 6 and the movable electrode 7. It is configured so that it can be pinched. The welding gun 2 is supported by the welding gun support member 3 and attached to the robot arm 4. As shown in FIG. 2, the welding gun support member 3 includes a rod 14 for supporting the welding gun 2 by two rods 14, 15 slidably supported by bearings 10, 11, 12, 13 on a base 9. , 15 are fixed to the gun arm 5 of the welding gun 2 at their lower ends. Rod 1
Springs 16 and 17 for floatingly supporting the welding gun 2 are attached to the rods 14 and 15 above the rods 4 and 15, respectively, and urge the rods 14 and 15 in the lifting direction. Brake pads 20 and 21 for sandwiching the rods 14 and 15 are provided at the center of the base 9, and the brake pads 20 and 21 are provided to the rods 14 and 15 by a brake cylinder 19 provided on the upper portion of the base 9. Brake and release for is operated. The brake pads 20, 21 and the brake cylinder 19 constitute a fixing means for fixing the welding gun 2 supported in a floating state at an arbitrary position. As shown in the sectional view of FIG. 3, the fixing means inserts a piston rod 22 by a brake cylinder 19 at an intermediate position between two sets of brake pads 20 and 21 that clamp the rods 14 and 15 by spring pressure. As a result, the spring pressure applied by the spring (not shown) acting on the brake pads 20 and 21 is released, and the brake is released.
The brake is operated by pulling out the piston rod 22. When the brake is opened, the welding gun 2 can be supported in a floating state, and the welding gun 2 in a floating state can be fixed at an arbitrary position by operating the brake.

In the robot spot welding apparatus 1 having the above structure, the piston rod 22 is retracted to open the brake pads 20 and 21 prior to the welding operation on the work, and the work position reference jig installed near the welding work position. The welding gun 2 is supported and moved to the position of the tool 23 in a floating state. As shown in FIG. 1, the work position reference jig 23 is provided with a reference surface 24 at the same height position as one surface of the work placed at the work position. When the work position reference jig 23 is moved to this position, the welding gun 2 is moved by the robot. The fixed electrode 6 by moving the
Is stopped at a position where it abuts against the reference surface 24, and the piston rod is advanced to operate the brake pads 20 and 21 of the fixing means to operate the welding gun 2 in the floating support state.
Is a fixed support. This stop position is a position where the robot moves to the welding position and stops the welding gun 2 by bringing the fixed electrode 6 into contact with one surface of the workpiece, and the robot stores the stop position. When the fixed electrode 6 comes into contact with the reference surface 24, the robot operation is stopped and the fixing means is operated by a method such as detecting the conduction between the fixed electrode 6 and the reference surface 24. Since the wear of the electrodes 6 and 7 of the welding gun 2 progresses due to repeated welding, the welding gun 2 is moved to the position of the work position reference jig 23 by a robot every predetermined number of times of welding, and the fixed electrode 6 Correct the contact position with the work. The robot taught the contact position of the fixed electrode 6 to the work as described above moves to the welding position where the work is arranged, and stops with the fixed electrode 6 abutting on one side of the work. The welding gun 2 can perform spot welding between the fixed electrode 6 and the fixed electrode 6 if the movable electrode 7 is driven to advance by the cylinder 8.

[0008]

As described above, according to the present invention, the welding gun is supported by the welding gun support member so as to be floatable with respect to the robot arm, and the welding gun is aligned with the clamp position of the work every predetermined cycle of the welding operation. The robot is moved to the jig position where the reference plane is installed, and the welding gun is fixed by the fixing means at the position where the fixed electrode is brought into contact with the reference plane. This operation teaches the robot the contact position of the fixed electrode to the work according to the degree of wear of the electrode. Therefore, even when the robot moves the welding gun to the work to perform welding, the fixed electrode accurately The spot welding can be performed by contacting one side of the workpiece and stopping the movement, and applying no deformation pressure to the workpiece.

[Brief description of drawings]

FIG. 1 is a side view showing the configuration of a robot spot welding apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view showing the configuration of the welding gun support member according to the embodiment.

3 is a sectional view taken along the line AA of FIG.

FIG. 4 is a side view showing the configuration of a conventional robot spot welding apparatus.

[Explanation of symbols]

 1 --- Spot welding equipment for robots 2--Welding gun 3--Welding gun support member 4--Robot arm 6 --- Fixed electrode

Claims (1)

[Claims] 1. A fixed electrode of a welding gun attached to the tip of a robot arm is brought into contact with one surface of a work, and a movable electrode facing the fixed electrode and supported so as to move back and forth is advanced toward the work. In a robot spot welding apparatus for energizing both sides of a work by sandwiching it between the fixed electrode and the movable electrode, a welding gun support member that supports the fixed electrode in a floating manner in the robot arm in the advancing direction of the movable electrode, A spot welding apparatus for a robot, comprising: a fixing means for fixing the fixed electrode at an arbitrary floating position.