JPS6142692Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a spot welding gun equipped with a stopper commonly referred to as a "chill metal" for preventing indentations from occurring in spot welds.

As is well known, spot welding is a method in which the workpiece is pressurized and energized by an electrode tip under certain conditions, and weld nuggets are generated at the welding point by resistance heat generation and welded. be.

In general, in spot welding, in order to obtain an appropriate weld, the amount of heat generated in the weld and the distribution of pressure force are affected by the shape of the tip of the electrode tip, so the appropriate tip shape of the electrode tip is usually C-shaped. Or R
The shape is the main thing.

In actual spot welding, a large current of several thousand to tens of thousands of amperes is applied intensively to the welding point through the electrode under an electrode pressure of 100 to 300 kgf, so the tip of the electrode tip is on the surface of the nugget-generating part. It is normal to leave a slight indentation.

However, for reasons of appearance or manufacturing, there are cases where this indentation should not be exposed on the surface of the base material. Normally, in this case, the flatness of the welded portion is ensured by using a flat electrode on the thin plate or outer plate side, where impressions are averse.

Recently, there has been a growing trend for spot welding to be carried out efficiently with short takt times using industrial robots. Since then, spot welding guns of the type shown in Figure 2 have been widely used. For example, as shown in Fig. 1, this type of spot welding gun welds a flat welding gun only on the surface of the outer plate (S ₂ ), which must not make any impressions, between the inner plate (S ₁ ) and the outer plate (S ₂ ). A dowel 20 is applied, and a pair of electrodes 7 and 8 apply narrow pressure and current to the welding location from above the dowel to flatly weld only the outer surface of the base material to which the dowel has been applied.

However, in this type of conventional spot welding gun, as specifically shown in FIG. 2, the pad 20 is fixed to one of the gun arms 2 and 3, so it does not leave an impression on the outside. In order to prevent this, the attitude direction of the spot welding gun body 1 must be controlled so that the pad is always on the outer plate (S ₂ ) side. When welding a welding point all around the four sides, the spot welding gun must be rotated 360 degrees, which makes the welding gun's operation unsmooth and also increases the rotational range of the robot's wrist. In addition to the secondary cable 25 and hose 26 attached to the welding gun.
It had the disadvantage of accelerating the wear and tear of products.

The present invention solves the above-mentioned drawbacks, and is characterized by making the stopper for preventing impressions movable so that it can be moved to either side of the electrode tip of the welding gun at will. A spot welding gun is provided.

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

FIG. 3 shows an embodiment of a spot welding gun in which the pad is operated in a swinging manner. 1 refers to the spot welding gun body. The gun arms 2 and 3 are supported by a support member 4 via a support shaft 5 so as to be rotatable in an X shape.

A pressure cylinder 6 is connected to the rear of each arm 2, 3 and applies pressure between electrode tips 7, 8 attached to the tips of each arm 2, 3. 9,10
is a connection terminal for connecting a pair of positive and negative secondary cables. Reference numerals 11 and 12 indicate connection holes for water cooling hoses.
Reference numeral 13 denotes a mounting member on the robot side, which fixes the support member 4. 14 is a ring, one end of which is connected to the support member 4
It is rotatably attached to the tip of the cylinder 16 via a support shaft 15, and the other end is rotatably connected to a rod 17 of a cylinder 16 which is swingably supported by the support member 4. 19 is a leaf spring made of a resilient member, and link 1
It is attached to 4. A stopper 20 made of a conductive member is attached to the tip of the leaf spring 19.
A water passage hole 21 is provided inside the pad to prevent the temperature from rising due to high heat caused by cooling water supplied from the outside.

According to the embodiment shown in FIG. 3, if the cylinder 16 is moved forward after opening the electrodes from the state shown in the figure, the link 14 swings as shown by the arrow A, and the leaf spring 19 moves as shown by the dashed line. The pad 20 can be shifted to the tip of another electrode tip.

FIG. 5 shows an example of a shift method as another embodiment. In this case, the sliding member 21 supporting the pad 20 is connected to the guide bar 22 of the supporting member 4.
When the sliding member 21 is shifted by a cylinder 23 fixed to the supporting member, the pad 20 can be shifted to either side of the electrode chip. It is. This spot welding gun equipped with a shift type dowel is more useful than the one shown in FIG. 2 when welding deep welding points without making impressions. This is because it is possible to largely shift the pad and the sliding member, thereby preventing interference with the workpiece to be welded inserted into the gun arm. Reference numeral 24 is a cover for preventing spatter from adhering to the sliding portion.

In addition, since the pad according to the present invention is supported by a leaf spring, it can be moved following electrode pressure during welding, so that it can be brought into complete contact with the surface of the base material.

As explained above, according to the present invention, compared to conventional spot welding guns with fixed pads, the pad can be shifted to either side of both electrodes, so that the welding area on the opposite side can be fixed. The rotation angle of the welding robot's wrist can be reduced even if the welding robot's wrist is always applied from one direction, eliminating the need for sophisticated control mechanisms and eliminating the need for harsh movements on secondary cables and hoses. Moreover, since the pad can be brought into complete contact with the surface of the base material without interfering with the movement of the spot welding gun, it is extremely effective as a measure to prevent impressions.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an example of a conventional spot welding gun and how it is used. FIG. 2 is an explanatory diagram of welding using a mark-preventing pad at the welding location. FIG. 3 is a front view showing an embodiment of the welding gun according to the present invention. Figure 4 is its plan view. FIG. 5 is a schematic front view showing another embodiment of the present invention. Explanation of symbols, 1...Spot welding gun body,
2, 3... Gun arm, 4... Support member, 7, 8
...Electrode chip, 14...Link, 16,23...
...Cylinder, 19...Plate spring, 20...Block,
21...Sliding member.

Claims (1)

[Claims for Utility Model Registration] 1. In a spot welding gun in which a pad is interposed between opposing electrodes to prevent indentations, the pad can be freely shifted to either side of both electrode tips. A spot welding gun with a pad for preventing indentation, characterized in that the spot welding gun is movably attached to the welding gun body side so that the spot welding gun can be moved. 2 Utility Model Registration The spot welding gun according to claim 1, characterized in that the pad is supported by a link swingably attached to the welding gun body side by a cylinder. Spot welding gun with pad for use. 3. The spot welding gun according to claim 1 of the utility model registration claim, characterized in that the metal is supported by a sliding member that is shiftably attached to the welding gun body side by means of a cylinder. Spot welding gun with pad to prevent indentation. 4 Utility Model Registration The spot welding gun according to claim 2 or 3 is characterized in that the pad is supported via a resilient member so as to be able to follow the movement of the electrode when pressurizing the electrode. A spot welding gun with a pad to prevent indentation. 5. The spot welding gun with a pad for preventing indentation, characterized in that the resilient member is a plate spring in the spot welding gun according to claim 4 of the utility model registration claim. 6. In the welding gun according to any one of claims 1 to 5 of claims 1 to 5 of the utility model registration, a water passage hole for circulating cooling water from the outside is provided inside the pad. A spot welding gun with a pad to prevent indentation.