JPS6235867B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spot welding device for welding a vehicle body floor panel, particularly a tunnel portion, in a vehicle body welding assembly line.

As shown in FIG. 1, when the front floor panel 2 and rear floor panel 3 of the vehicle body floor panel 1 are jointed together by spot welding, the vertical wall portion 5 of the tunnel portion 4 is conventionally welded using, for example, Spot welding equipment exclusively used for tunnel parts is used, which is made by combining a large welding gun shown in FIGS. 2 and 3 with an industrial robot.

Specifically, what is shown in FIG. 2 is a rectangular coordinate type robot 6 and a modified C-type spot welding gun 7 disclosed in FIG. 2 of JP-A-57-124582, for example.
The arm 8 is attached to the wrist 6a of the robot 6 via an equalizing mechanism 20. In other words, equalizing mechanism 2
Both ends of the base 21 of the arm 8 inserted through the guide rod 20a of the robot 6 are sandwiched between springs 22 and 23, and the compression reaction force of the springs 22 and 23 is used to absorb the pressure reaction force applied to the wrist 6a of the robot 6 during welding. .

The arm 8 has a long lower arm 11 that reaches from the side part of the floor panel 9 that is the object to be welded to the central tunnel part 10, and a shorter upper arm 12, and these two arms are integrally formed in a so-called C shape. It forms a shape. A push-pull type stud gun 13 with a built-in pressure cylinder is fixed to the tip of the lower arm 11 so as to form a constant elevation angle toward the gun insertion side (robot side), while the tip of the upper arm 12 is fixed to the tip of the upper arm 12. Another stud gun 14 is attached to the stud gun 13 on the lower arm 11 side at a constant angle of depression during welding.
This allows welding to occur on the vertical wall portion 15 on the gun insertion side (the side closer to the robot).
It is now being done at

Further, the stud gun 14 on the upper arm 12 side has a hinge portion 17 with a separate rotation cylinder 16.
By moving the gun up and down within a certain range as shown by arrow A around the center, an opening area is ensured when inserting and retracting the gun, and interference with the object to be welded is prevented. During welding, the workpiece is held between the tips 18 and 19 of both stud guns 13 and 14, and both tips 18 and 19 are held under pressure.
This is done by energizing the.

In addition, each stud gun 13, 14 is attached to the arm 8.
Air piping to cylinder 16, chips 18, 19
A lot of wiring and piping, such as cables that supply welding power and cooling water piping, are routed from each supply source.

In the case shown in FIG. 3, a locking arm 26 is further connected to the tip of the lower arm 24 via a hinge pin 25.
This is an example in which the so-called Rotsukagan 27 with a
(Disclosed in Figure 4 of Publication No. 124582). That is, the tip 28 is attached to the upper end of the rocker arm 26 toward the gun insertion side, and the rod 29a of the pressure cylinder 29 is connected to the lower end of the tip 28.
This differs from the stud gun 13 in FIG. 2 in that it enables welding when the cross section is narrow, but the other configurations are the same.

However, in such conventional spot welding equipment, the stud gun 13 or lock gun 27 is used with a cylinder on the lower arm 11 or 24 side, so the entire gun including the wiring and piping system attached to them is damaged. In addition to being very large in terms of shape and weight, welding is inevitable due to the interference between the gun and the object to be welded, as well as the interference with the conveyance device on the underside of the object. There is a problem that the shape of the part is severely restricted and it lacks versatility. In addition, as the weight increases as mentioned above, the moment of inertia also increases, so there is a problem that the robot that supports the entire gun will have a reduced operating capacity unless a heavy-load type is used. .

The present invention has been made in view of the above-mentioned points, and it solves the above-mentioned conventional problems by adopting a structure in which a single electrode chip is used in place of the stud gun 13 or rocker gun 27, and by effectively combining it with an equalizing mechanism. The purpose is to eliminate it.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

4 and 5 show an embodiment of the spot welding apparatus of the present invention. First, the overall configuration will be explained based on FIG. 4. 40 is an orthogonal coordinate type industrial robot, 41 is a A spot welding gun 42 attached to the wrist 40a of the industrial robot 40
4 is a transformer; 43 is a transfer bar having fingers 43a and moving in a direction perpendicular to the plane of the paper; 4;
4 is a lifter having a receiving piece 44a that moves up and down. Then, the object to be welded, that is, the floor panel 45, which is being transported by the transfer bar 43, is lifted up to a predetermined height by the receiving piece 44a rising from below, and then the robot 40 is moved from the right side.
A welding gun 41 that moves forward at the same time performs spot welding on a predetermined portion.

As shown in FIG. 5, the welding gun 41 has an arm 46 that is generally C-shaped as a whole and has a long lower arm 46a that reaches from the side part of the floor panel 45 to the tunnel part 45a and an upper arm 46b that is shorter than this. The arm 46 is supported by an equalizing mechanism 47, and the equalizing mechanism 47 is connected to the wrist 40a of the robot 40 via a bracket 48. This equalizing mechanism 47 is
As mentioned above, since the purpose is to absorb the reaction force when pressurizing the gun, it is installed in a position parallel to the axial direction of the stud gun 57 at the welding position, as described later. There is. Then, as shown in Fig. 6, a pair of guide rods 4
The center base 46C of the arm 46 is slidably supported between 9 and 9, and when a reaction force when pressurizing the gun acts in the direction of arrow B, the reaction force is attenuated by the air cylinder 50. When a directional reaction force is applied, the spring 51 is designed to attenuate the reaction force.

That is, the arm 46 has an air cylinder 50 and a spring 51, which are elastic means having a mutually antagonistic effect, to support the electrode tip 58, which will be described later.
It is elastically supported so that it can be displaced in the same direction as the axial direction of the stud gun 57 (at the welding position). Nao 52
is a bolt for position adjustment.

A lower electrode chip (hereinafter referred to as lower chip) 58 is directly attached to the tip of the upright portion 46d of the lower arm 46a, while an auxiliary arm 53 is attached to the tip of the upper arm 46b via a hinge pin 54. Further, a stud gun 57 having an upper electrode tip (hereinafter referred to as upper tip) 56 at its tip is attached to the auxiliary arm 53. The auxiliary arm 53 is rotatable about the hinge pin 54 by the operation of the rotation cylinder 55. That is, the auxiliary arm 53 and the body stud gun 57 are connected to the rotating cylinder 5.
5, it becomes possible to rotate between the welding position shown by the solid line in FIG. 5 and a retracted position (imaginary line position) that does not interfere with the floor panel 54.

According to the spot welding apparatus having the above configuration, when the floor panel 45, which is the workpiece to be welded, is set at a predetermined height position in a horizontal position by raising the receiving piece 44a as shown in FIG. The welding gun 41 in the open state is moved forward by the action of the robot 40. Then, when the welding gun 41 approaches the tunnel portion 45a of the floor panel 45, the upright portion 46d enters the inside of the tunnel portion 45a and the rotation cylinder 55 is operated, thereby rotating the stud gun 57. 56 faces the other lower tip 58, and their axes coincide.

Subsequently, the cylinder built into the stud gun 57 operates, and the upper tip 56 moves forward relative to the lower tip 58, applying the vertical wall portion 45b of the tunnel portion 45a on the gun entry side between the two tips 56, 58. Press and hold. Then, spot welding is performed by applying a predetermined welding current from the transformer 42 under this pressurized state.

When the spot welding of a predetermined number of welding points is completed, the stud gun 57 is rotated and raised to the extent that the welding gun 41 and the floor panel 45 do not interfere when the welding gun 41 moves backward, and the welding gun 41 moves back together with the robot 40. This will prepare you for welding the next workpiece.

Here, the operation of the equalizing mechanism 47 will be explained as follows.

As described above, after the auxiliary arm 53 is brought into the state shown by the solid line in FIG. 5, the upper tip 56 is advanced to press and clamp the vertical wall portion 45b. If the mutual distance between the auxiliary arm 53 and the tunnel section 45a is smaller than a predetermined value due to a teaching error in the robot or the robot, the upper tip 56 will receive a reaction force from the vertical wall section 45b, but the pressing force of the stud gun 57 will not be applied. is applied to the upper tip 56, the central base 46c of the arm 46 moves in the direction of arrow B (see FIG. 6) while contracting the air cylinder 50, and presses the lower tip 58 against the vertical wall 45b. ing. Therefore, it is possible to perform good pressurization and clamping, and also to prevent the occurrence of dents in the tunnel portion 45a. On the other hand, when the welding gun 41 is moved by the robot's wrist 40a, the lower chip 5
8 collides with the vertical wall portion 45b, the lower tip 58 receives a reaction force from the vertical wall portion 45b, and the central base 46c of the arm 46 compresses the spring 51 while moving in the direction of arrow B (see FIG. 6). ) to prevent dents on the vertical wall portion 45b and to enable good pressurization and clamping.

In the series of operations described above, there is no pressure cylinder or rocker arm provided on the lower arm 46a side, that is, on the lower tip 58 side, so there is no need to be as concerned about interference with the workpiece as in the past. One type of welding gun can be used for various vehicle models with different tunnel shapes or dimensions.

Furthermore, as mentioned above, in addition to the absence of the pressure cylinder and rocker arm on the lower arm side, relatively heavy members such as the minimum required rotation cylinder 55 and the auxiliary arm 53 are used in the equalizing mechanism 47 as much as possible. Since they are arranged close to each other, the weight of the tip of the arm is reduced, and the penetrating moment is thereby reduced, so that the robot 40 will not be overloaded.

As described above, according to the present invention, it is possible to ease the restrictions on the shape of the welding part and provide versatility, and also to reduce the pressure cylinder on the lower arm side, the rocker arm, and the wiring and wiring attached thereto. Since there is no wiring system, the entire welding gun can be made smaller and lighter, which has the effect of keeping the load weight of the robot small.

[Brief explanation of the drawing]

Figure 1 is a partial perspective view of the car body floor panel;
The figure is a schematic diagram of a conventional spot welding device for car body floor panels, FIG. 3 is a schematic diagram showing another conventional example, and FIG. 4 is an overall schematic diagram showing an embodiment of the spot welding device according to the present invention. , FIG. 5 is an enlarged explanatory view showing details of the welding gun shown in FIG. 4, and FIG. 6 is an enlarged explanatory view showing details of the equalizing mechanism shown in FIG. 5. 40...Industrial robot, 40a...Wrist, 4
1... Spot welding gun, 45... Vehicle floor panel, 45a... Tunnel section, 46... Arm,
47... Equalizing mechanism, 50... Air cylinder as elastic means, 51... Spring as elastic means, 53... Auxiliary arm, 54... Hinge pin, 55... Rotating cylinder, 56... Electrode chip, 57 ... Stud gun, 58... Electrode chip.

Claims (1)

[Claims] 1 In a spot welding device that performs spot welding on the tunnel part of a car body floor panel in a horizontal position,
A C-shaped arm is attached to the wrist of an industrial robot via an equalizing mechanism, an electrode chip is directly fixed to the lower end of this arm, and the electrode chip is hinged to the upper end of the arm. The arm is equipped with a push-pull type stud gun that can be rotated between opposing welding positions and retracted positions, and the arm is configured to move the electrode tip by an elastic means that is built into the equalizing mechanism and has a mutually antagonistic action. A spot welding device for a car body floor panel characterized by being elastically supported so as to be displaceable in the same direction as an axis.