JPH0349672B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is a spot welding device, specifically, a spot welding device that prevents workpiece deformation to improve quality, and absorbs welding electrode wear, workpiece loading errors, etc. This invention relates to a spot welding device that can perform proper welding.

(Prior Art) Conventionally, as this type of spot welding apparatus, the one shown in FIG. 6 is known.

In the figure, 20 is a C-shaped welding device main body,
The welding device main body 20 is supported by a support 23 erected on a floor 22 via an equalizing device 21 equipped with a balance spring (not shown), and has a cylinder 24 at the tip of its upper arm 20A. The upper electrode 25 is movably attached to the tip of the lower arm portion 20B.
A lower electrode 26 facing the upper electrode 25 is fixed.

In the spot welding apparatus configured as described above, when the workpiece is carried into the carry-in position by the carry-in device (not shown) and held on the jig, the upper electrode 25 is lowered by the operation of the cylinder 24.
It comes into contact with the top surface of the workpiece at the welding position.

Further, when the cylinder 24 is actuated, the upper electrode 25 presses the upper surface of the welding position of the workpiece, and the welding device is lifted against the spring force of the equalizing device 21, thereby causing the lower electrode 26 to weld the workpiece. Spot welding is performed by contacting the lower surface of the workpiece, holding the workpiece between the lower electrode 26 and the upper electrode 25, and applying electricity.

However, in the conventional spot welding device described above, the spring force of the equalizing device 21 is set to be considerably large because it is necessary to support the heavy device main body 20 on the pillar 23 without swinging. In order to lift the device main body 20, the upper electrode 25 presses the upper surface of the workpiece at the welding position with a large pressing force,
As a result, the welding position of the workpiece is pushed downward and deformed, resulting in a problem of deterioration of quality.

In addition, in cases where the lower electrode 26 is worn out due to polishing and the amount of upward movement of the apparatus main body 20 becomes large, or when an error occurs in the loading position of the workpiece and the amount of upward movement of the apparatus main body 20 becomes large, etc. Since it does not have the function of absorbing the wear of the lower electrode 26 and the error in the loading position, the upper electrode 2
There is a problem in that the pressing force on the workpiece No. 5 becomes even greater, and the deformation of the workpiece increases.

(Purpose of the Invention) This invention was made to solve the above-mentioned conventional problems, and it aims to improve quality by preventing workpiece deformation, and also absorbs welding electrode wear, workpiece loading errors, etc. It is an object of the present invention to provide a spot welding device that can perform proper welding.

(Structure of the Invention) In order to achieve the above object, the present invention includes an apparatus main body for spot welding a workpiece held on a jig;
It has a cylinder to which a passive electrode is attached and is normally biased in the direction of extension using an incompressible fluid such as antifreeze or oil as a working fluid, and is pushed back by contacting the passive electrode when the workpiece is set on the jig. The fluid supply circuit of the cylinder is provided with a switching valve that locks the cylinder when positioning of the workpiece is completed, and a passive electrode support means attached to the apparatus main body, and a switch valve provided opposite to the passive electrode support means. The movable electrode supporting means supports the movable electrode with a cylinder and holds the work together with the locked passive electrode.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a side view showing an embodiment of a spot welding apparatus according to the present invention. In the figure, 1 is a welding apparatus main body, and a support 4 is erected on a floor 3 via a support member 2. is supported by the upper arm portion 1A.
and a lower arm portion 1B.

5 is a passive electrode support means, 6 is a movable electrode support means, the passive electrode support means 5 is composed of a passive electrode 5A, a cylinder 5B, and a fluid supply circuit 5C, and the movable electrode support means 6 is composed of a movable electrode 6A and a cylinder 6B. Become.

The passive electrode support means 5 is provided at the tip of the lower arm portion 1B of the device main body 1, and the passive electrode 5A is attached to a cylinder 5B. The cylinder 5B is normally expanded using a non-compressible fluid such as antifreeze or oil as a working fluid. direction, that is, upward in this embodiment.

A fluid supply circuit 5C is connected to the cylinder 5B, and the fluid supply circuit 5C includes a switching valve 51 and a hydraulic/pneumatic converter 5 connected in series to the switching valve 51.
2.

The hydraulic/pneumatic converter 52 is partitioned into a front chamber 52a and a rear chamber 52b by a piston 52A.
The passage 7 that communicates the cylinder 5B with the cylinder 5B is filled with an incompressible fluid such as the antifreeze or oil, and a switching valve 51 is interposed therein.

Further, the rear chamber 52b of the hydraulic/pneumatic converter 52 is
It communicates with an air chamber 9 via a passage 8,
Air pressure in passageway 8 acts on the incompressible fluid via piston 52A, thereby urging passive electrode 5A upwardly via cylinder 5.

Note that the air pressure in the passage 8 is set to a level that supports the weight of the passive electrode 5A by the liquid pressure in the passage 7.

Reference numeral 10 indicates a loading/unloading robot, a jig 11 is attached to the tip of its arm portion 10A, and the robot is placed on a table 12 by opening and closing a clamp cylinder 11A provided on the jig 11. The workpiece 13 is attached to and detached from the jig 11.

In the above configuration, the workpiece 13 placed on the stand 12 in FIG.
0 and the clamping cylinder 11A, the workpiece 13 is placed above the passive electrode 5A by the operation of the loading/unloading robot 10, as shown in FIG. transported to the corresponding loading position.

Next, the workpiece 1 clamped on the jig 11 is moved by the loading/unloading robot 10.
Lower 3. In this case, since the hydraulic pressure of the cylinder 5B that urges the passive electrode 5A upward is large enough to support the weight of the passive electrode 5A, the passive electrode 5A is pushed down by the lowering of the workpiece 13. , the workpiece 13 is lowered to the welding position shown in FIG. At this time, that is, when the workpiece 13 is positioned at the welding position, the switching valve 5 in FIG.
1 is switched as shown in Fig. 4 to lock the cylinder 5B and stop the lowering of the passive electrode 5A, and then actuate the cylinder 6B in Fig. 1 to push down the movable electrode 6A, as shown in Fig. 5. In cooperation with the passive electrode 5A, the workpiece 13 is held and spot welded.

After spot welding is completed, cylinder 6B (Fig. 1)
is activated to raise the movable electrode 6A, and then the loading/unloading robot 10 is activated to carry out the workpiece 13 from the welding completion position, and at the same time, the switching valve 51 shown in FIG. 4 is switched as shown in FIG. 1, cylinder 5
Activate B to return the passive electrode 5A to the upward position and prepare for the next welding.

In this way, the hydraulic pressure of the incompressible fluid that holds the passive electrode 5A in the standby position shown in FIG.
After contacting the passive electrode 5A, the passive electrode 5A is pushed back to the welding position by the weight of the workpiece 13, and when the positioning of the workpiece 13 is completed, the cylinder 5B is locked and the passive electrode 5A is stopped and the movable electrode 6B is pressed against the workpiece 13 at this position for welding, so no large force is applied to the workpiece 13, so the workpiece 13 is not deformed.

Furthermore, even if the passive electrode 5A is shortened by being polished, the length of the workpiece 13 that pushes down the passive electrode 5A to the welding position is only shortened;
Furthermore, even if the movable electrode 6A is shortened due to polishing, the size by which the movable electrode 6A is pushed down by the cylinder 6A will only increase, and the amount of wear on both electrodes 5A and 6A can be absorbed by this. ,
The workpiece 13 is not deformed as in the conventional case.

Further, even if a slight error occurs in the loading position of the workpiece 13 and the amount of movement to reach the welding position changes, the workpiece 13 will not be deformed.

In the above embodiment, the workpiece 13 is held by the jig 11 attached to the tip of the arm portion 10A of the loading/unloading robot 10. However, the present invention is not limited to this, and a separate jig 11 may be arranged near the welding apparatus main body 1, and the workpiece 13 may be held and positioned on this jig 11.

(Effects of the Invention) As explained above, according to the present invention, it is possible to improve the quality by preventing deformation of the workpiece, and also to absorb wear of the welding electrode, errors in loading the workpiece, etc., and to perform proper welding. can be done.

[Brief explanation of drawings]

Fig. 1 is a side view showing an embodiment of the spot welding device according to the present invention, Fig. 2 is a side view showing the workpiece being carried into the carry-in position, and Fig. 3 is a side view showing the workpiece being positioned at the welding position. A side view showing the condition,
FIG. 4 is an explanatory view showing the switching state of the switching valve, FIG. 5 is a side view during spot welding, and FIG. 6 is a side view showing an example of a conventional spot welding device. 1... Apparatus main body, 5... Passive electrode support means, 5
A... Passive electrode, 5B... Cylinder, 5C... Fluid supply circuit, 6... Movable electrode support means, 6A...
Movable electrode, 6B... cylinder, 51... switching valve.

Claims (1)

[Claims] 1 A device for spot welding a workpiece held on a jig, which has a main body and a passive electrode attached, and is normally biased in the direction of extension using an incompressible fluid as a working fluid to weld the workpiece onto the jig. The apparatus has a cylinder in which the workpiece comes into contact with the passive electrode and is pushed back when the workpiece is set in the position, and the fluid supply circuit of the cylinder is provided with a switching valve that locks the cylinder when the positioning of the workpiece is completed. a passive electrode support means attached to the passive electrode support means, and a movable electrode support means provided opposite to the passive electrode support means, supporting the movable electrode with a cylinder and clamping the workpiece together with the locked passive electrode. Spot welding equipment featuring: