JP3089388B2 - Gun arm for welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to the welding gun arm to be used in the welding gun.

[0002]

2. Description of the Related Art Conventionally, a welding gun arm used for a welding gun is formed of a good conductor such as an aluminum alloy or a copper alloy.

[0003]

In resistance spot welding of a work, a part of the melted work is so-called scattering or spatter (hereinafter, referred to as "spatter") from a hit point of the work when welding is conducted.
(Generally referred to as sputter) and scattered around, and a part thereof adheres and deposits on the gun arm.

When the spatter deposited on the gun arm is observed with a microscope, as shown in FIGS. 3A and 3B, a massive sputter b adheres on the gun arm a, and a dendritic sputter c adheres thereon. A sputter deposited layer was formed.

[0005] The spatter b comes from the gun arm surface as relatively large particles, and some of the spatters have a high temperature of about 1200 ° C., and thus adhere to the gun arm surface in a lump. 3A, some sputters b melt the surface of the gun arm and adhere firmly, as shown in FIG. When the gun arm is made of a copper alloy, as shown in FIG. 3B, the spatter b hardly penetrates into the gun arm, but the adhesion is still large. Further, it is considered that the spatter c is relatively small particles and scattered from the work, and is partially cooled down in the air when flying to the gun arm, so that the spatter c changes into a dendritic shape and adheres to the gun arm.

As described above, at least the sputtering involves
If the removal is neglected by the deposition of these spatters, the gun arm and the member of the welding gun to be insulated therefrom are finally bridged through the sputter deposition layer, and the leakage of the welding current occurs. Will occur.
Therefore, it is necessary to frequently remove the spatter, and the operation rate of the welding gun decreases.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a welding gun arm capable of suppressing spatter deposition as much as possible.

[0008]

In order to achieve the above object,
Welding gun arm of the present invention, the sputtering of the arm body
The method is characterized in that a fine powder of a magnetic material is applied to the surface of the arm body in order to suppress the deposition of the magnetic material.

[0009]

A dendritic material such as sputter c in FIG. 3, which is normally difficult to adhere, adheres to the gun arm, and sputter adheres and grows perpendicular to the gun arm. This phenomenon is considered to be due to the fact that a flying sputter is magnetized by a magnetic field generated around the gun arm by a current supplied to the gun arm, and adheres by interaction with the magnetic field. That is, the spatters themselves
While being magnetized by crossing the magnetic field, the magnetic field advances near the surface of the gun arm where the magnetic field is strong, adheres to the surface of the gun arm so as to be attracted, and eventually deposits. If the magnetic field around the gun arm generated by the current supplied to the gun arm is cut off, the flying sputter will not be magnetized, and the spatter adhered by the magnetization will be eliminated.

According to the present invention, since the surface of the arm body is provided with a magnetic material, the surface of the gun arm becomes a magnetic layer, and the magnetic flux generated around the arm body when energized is concentrated on this magnetic layer. The magnetic field around the gun arm is weakened, and adhesion due to sputter magnetization is suppressed. As a result, the growth rate of the sputter-deposited layer is reduced, so that it is not necessary to frequently remove spatter, and the operating rate of the welding gun is improved.

[0011]

FIG. 1 shows a resistance spot welding gun, in which electrodes 1a and 2a are attached to the tips of a pair of gun arms 1 and 2 and a work W is clamped between the electrodes 1a and 2a. The work W is spotted by supplying power to the workpiece 2.

Each of the gun arms 1 and 2 is shown in FIG.
As shown in ( C ), a fine powder of a magnetic material 11 is adhered to the surface of an arm body 10 formed of an aluminum alloy such as A6061P-T6 or a copper alloy such as HBsCIn2 or HBsC2. And As the magnetic material 11, γ-Fe
₂ O ₃ , Co, Fe, FeO, Fe ₃ O ₄ , CrO _{2 and the} like can be used.

[0013] Here, in the embodiment of FIG. 2 (A), the dispersion obtained by mixing a fine powder of a magnetic material 11 (e.g., an organic coating material,
Using a resin (before curing)), a coating material 12 made of an organic paint or resin mixed with a fine powder of a magnetic material 11 was applied to the surface of the arm body 10 by coating or dipping.
As shown in (B), the adhesive 13 is applied to the surface of the arm body 10.
The fine powder of the magnetic material 11 may be adhered through the step. A sheet or tape-like material 14 in which fine powder of a magnetic material 11 is dispersed as shown in FIG.
May be applied by a wrapping method.

When a metal such as Co or Fe is used as the magnetic material 11, a highly insulating material is used as the coating material 12 or the adhesive 13 so that the magnetic material 11 is insulated from the arm body 10, The welding current is prevented from flowing through the magnetic material 11. When the magnetic material 11 is γ-Fe ₂ O ₃ , FeO,
When it is a metal oxide such as Fe ₃ O ₄ or CrO ₂ ,
Since the magnetic material itself has insulating properties, there is no particular need to insulate the magnetic material 11 from the arm body 10.

When the magnetic material 11 is applied to the surface of the arm body 10 as described above, the magnetic flux generated by energizing each of the gun arms 1 and 2 is concentrated on this magnetic layer, and the space around the gun arms 1 and 2 is formed. Is magnetically shielded, and the magnetic field around the gun arms 1 and 2 is weakened. For this reason, the spatters flying to the gun arms 1 and 2 are less likely to be magnetized, and the deposition of spatters due to magnetic attraction is suppressed.

In the embodiment shown in FIGS. 2A and 2C, the coating material 12, the sheet
Even if the heat resistance is insufficient, the magnetic material 11 dispersed in these materials 12 and 14 blocks the incoming spatter, so that there is no problem such as melting of spatter.

The magnetic material 11 may be applied to the entire gun arm. However, the magnetic material 11 may be damaged by spatter deposition, for example, a portion where current leakage is likely to occur, such as a joint with an arm holder or an insulating portion, or the like. The electrode may be partially attached to the electrode mounting portion at the tip of the arm that hinders electrode replacement.

[0018]

As is apparent from the above description, according to the present invention, the sputter deposition can be suppressed as much as possible.
The frequency of spatter removal operation can be reduced, and the operation rate of the welding gun can be improved.

[Brief description of the drawings]

FIG. 1 is a side view of a main part of a welding gun having a gun arm of the present invention.

FIGS. 2A to 2C are cross-sectional views of a surface portion of a gun arm showing each embodiment of the present invention.

FIGS. 3A and 3B are diagrams showing a conventional sputter deposition state on a gun arm. FIGS.

[Explanation of symbols]

 1, 2 Gun arm, 10 Arm body 11 Magnetic material

Claims (1)

(57) [Claims] 1. A welding gun arm, comprising: an arm main body.
A welding gun arm characterized in that a fine powder of a magnetic material is applied to a surface of an arm body to suppress deposition of spatter on the arm.