JPH10128554A - Cap tip for spot welding, and cooling device of cap tip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deposition of a work to be welded by providing a through hole across the axial direction of a cap tip in the vicinity of a tip of the cap tip for an electrode to be fitted to a spot welding gun to increase the cooling surface by the through hole. SOLUTION: A flat top part 12 which is extended from a main part 11 and abutted on a part to be welded is formed smaller than the diameter of the main part 11, and a scooped surface 14 is formed from an intermediate part 13 to the flat top part 12. A through hole 15 to be communicated in the direction across the axis of a cap tip 1 is provided in the scooped surface 14. The cooling water introduced from a welding gun into a bottomed hole 16 of the cap tip 1 cools the cap tip 1. The temperature rise of the cap tip 1 is suppressed to approximately 50% compared with a conventional one by increasing the surface area in contact with the outside air by the through hole 15 to improve the air-cooling effect. The wear of the cap tip 1 is small, deposition of a work to be welded is prevented, and the service life can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cap tip used for an electrode of a spot welding gun and a cooling device for the cap tip.

[0002]

2. Description of the Related Art When spot welding a narrow place of an automobile body, for example, a drip channel portion at a joint portion between a roof panel and a side member, as shown in FIG.
Since the drip channel portion 7 formed by the channel 61 extending in the shape of a letter is narrow, the tip of the cap tip 110 used as an electrode of the spot welding gun 100 is thinned as shown in FIG.

That is, the tip end portion 102 of the cap tip 110 which is in contact with the drip channel 7 to be welded is formed to have a smaller diameter than the outer diameter of the main portion 101 of the cap tip 110, and an intermediate portion in the middle of the main portion 101. A cap chip 110 is formed by continuously forming a curving surface 104 having a curving shape from 103 toward the tip 102.

[0004]

When spot welding is performed using the cap tip 110 having such a thin tip, there are the following problems. That is, despite the fact that the tip of the cap tip is formed thin, it is necessary to perform welding at the same level as the normal cap tip, such as the pressing force, current value, and energizing time during spot welding. With a thin cap tip, the surface area at the tip is small, so that when spot welding is performed continuously, heat at the time of welding tends to accumulate, and therefore the cooling rate is low. If the cooling rate is low, the cap tip receives a pressing force for the next spot welding while the temperature is high, so that the wear (close to crushing) becomes faster as in the tip portion 102 'of the cap tip 110 shown in FIG. In a welding line for a body or the like, there is a problem that the frequency of replacement of cap chips is increased, so that the operation rate of the line is reduced, and the cost of replacing cap chips is increased.

Further, if the cap tip receives a pressing force while the temperature is high, the cap tip is welded to the work to be welded, so that subsequent spot welding cannot be performed, and line stoppage occurs, which also lowers the operating rate of the line. There is a problem to do.

Further, if the welding current and the pressing force are kept low in order to reduce the frequency of replacement of the cap tip and the frequency of welding with the work to be welded as described above, the spot welding portion is not sufficiently welded, and the spot separation is reduced. There is also a problem that the adjustment of the welding current and the pressing force cannot be extremely reduced because of the possibility of occurrence. Therefore, the appearance of a cap chip having high cooling efficiency and a cooling device for the cap chip has been desired.

[0007]

According to a first aspect of the present invention, there is provided a cap tip for an electrode to be attached to the tip of a spot welding gun, the cap tip being located near the tip of the cap tip. , A through hole is provided in a direction intersecting the axial direction of the cap chip. According to the spot welding cap chip of the first invention, the through-hole provided near the tip of the tip increases the surface area that can be exposed to the outside air on the inner surface of the through-hole, so that heat is easily transmitted to the outside air, It becomes easy to cool.

Further, the cap chip of the second invention is
At its tip, it has a flat head contacting with the workpiece, forms a scouring surface whose outer surface is gradually narrowed toward the flat head, and the through hole is provided in the area of the scouring surface. It is characterized by having. According to the cap tip of the second aspect of the present invention, the through hole is provided in the area of the undercut surface in which the outer surface of the cap tip facing the small-diameter planar head is gradually changed, so that spot welding of a narrow portion is performed. The surface area of the small-diameter portion where heat easily accumulates in the cap chip is increased, and the cap chip is easily cooled by the outside air.

The cooling device for a cap tip according to the third aspect of the present invention is characterized in that the cap tip having a through hole provided in a direction intersecting with the axial direction is jetted with compressed air for operating a spot welding gun. An injection nozzle for cooling the chip is provided. According to the cooling device for a cap tip for spot welding of the third aspect of the present invention, in addition to providing a through hole in the cap tip to increase the surface area exposed to the outside air, a spot welding gun holds and clamps a workpiece to be welded during spot welding. Since the exhaust of compressed air that drives the spot welding gun to pressurize is guided to the vicinity of the cap chip, the exhaust is ejected toward the cap chip, and forced cooling can be performed. Abrasion, welding, spot separation, etc. of the cap chip can be prevented.

[0010]

FIG. 1 is a view showing an embodiment of a cap tip for spot welding according to the present invention. The cap tip 1 has a main portion 11 and a cover extending from the main portion 11. It has a planar head 12 at the tip that abuts against the weldment (eg, drip channel 7 in FIG. 5). The plane head 12
Is formed thinner than the outer diameter of the main part 11,
A hollow surface 14 is formed continuously from the intermediate portion 13 of the main portion 11 to the flat head portion 12, and is formed to have a small diameter up to the tip of the cap chip 1. And the undercut surface 1
4 is provided with a through-hole 15 communicating with the surface opposite to the hole surface 14 in a direction intersecting with the axis of the cap chip 1. Reference numeral 16 denotes a bottomed hole for inserting the cap chip 1 into the electrode holder of the spot welding gun, into which cooling water guided from the spot welding gun is introduced to cool the cap chip. It is.

As described above, the through hole 1 is provided near the small diameter tip.
5 to increase the surface area exposed to the outside air, and measure the temperature of the cap chip when spot welding is performed using the cap chip 1 having an enhanced air cooling effect by the outside air. FIG. 3 shows a graph for comparison. As is clear from FIG. 3, the temperature rise of the cap chip 1 after pressurizing and energizing at the time of spot welding with about 4 seconds as one cycle is suppressed to about 50% as compared with the conventional cap chip 110, It turns out that the cooling effect is large.

Further, as shown in FIG. 4, when the tip of the cap tip 1 having an initial diameter of 6 mm is compared with the number of hit points until the tip of the cap tip 1 is worn to a diameter of 8 mm which requires replacement of the cap tip 1 by spot welding. Thus, spot welding of about four times the number of spots compared with the conventional cap chip 110 has become possible. Therefore, the replacement cycle of the cap chip 1 is quadrupled.

Next, a cap chip cooling device according to the present invention will be described with reference to FIG. In the spot welding gun 2, the cap tip 1 of the present invention is attached to the electrode holder 21 of the spot welding gun 2, and the spot welding gun 2 is mounted.
Hoses 23A and 23B for supplying compressed air to an air cylinder 22 for driving the air cylinder 22 are connected. The hose 23A,
23B is one port 24A, 24B of the electromagnetic switching valve 24
It is connected to the. Ports 24C and 24D are provided on the other side of the electromagnetic switching valve 24. A hose 25 for introducing compressed air (factory air) from a factory is connected to the port 24C, and the spot welding gun 2 is driven after the hose 25 is driven. To the discharge port 24D for discharging the compressed air, hoses 26, 26 having injection nozzles 27, 27 directed toward the cap chip 1 are connected near the cap chip 1 at the tip of the spot welding gun 2.

Therefore, the compressed air is discharged from the discharge port 24D in each cycle of pressurizing and non-pressurizing the work to be welded by the spot welding gun 2, and the compressed air is discharged from the discharge port 24D.
Nozzle 2 through hoses 26, 26 connected to
7 and 27, which are sprayed toward the cap chip 1, so that the temperature of the cap chip 1 becomes high due to spot welding.
Is more forcibly cooled than is cooled by outside air.

[0015]

As described above, according to the cap tip and the cap tip cooling apparatus of the present invention, the cap tip is cooled efficiently, so that the cap tip is less worn and the cap tip is welded to the workpiece. Can be prevented and the replacement cycle of the cap chip can be extended, so that the operation rate of the welding line can be significantly increased.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of a cap chip of the present invention.

FIG. 2 is a hose connection diagram of compressed air of the spot welding gun of the present invention.

FIG. 3 is a diagram showing a transition of a temperature of a cap chip to which a cap chip of the present invention is applied, in comparison with a conventional case.

FIG. 4 is a diagram showing a replacement cycle of a cap chip of the present invention in comparison with a conventional one.

FIG. 5 is a schematic view of a case where a drip channel portion of an automobile body is spot-welded.

FIG. 6 is an overall perspective view of a conventional cap chip.

FIG. 7 is an overall perspective view showing the state of wear of the tip of a conventional cap tip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cap tip 15 ... Through hole 2 ... Spot welding gun 26 ... Hose 27 ... Injection nozzle

Claims (3)

[Claims] 1. A cap tip for an electrode to be attached to the tip of a spot welding gun, wherein a through hole is provided near the tip of the cap tip in a direction intersecting the axial direction of the cap tip. Cap tip for spot welding. 2. The cap chip has a flat head at the tip thereof in contact with an object to be welded, and forms a hollow surface in which an outer surface is gradually narrowed toward the flat head, and the cap chip has a transparent surface. The cap tip for spot welding according to claim 1, wherein a hole is provided in a range of the undercut surface. 3. A cooling device for a cap tip for spot welding, wherein said cap tip is provided with an exhaust of compressed air for operating a spot welding gun toward a cap tip provided with a through hole in a direction intersecting an axial direction. An apparatus for cooling a cap tip for spot welding, comprising an injection nozzle for cooling the tip.