JP2995645B2 - Welding gun arm and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding gun arm used for a welding gun and a method for manufacturing the same.

[0002]

2. Description of the Related Art Heretofore, as a welding gun arm, an arm body formed of an aluminum alloy is known.

[0003]

In resistance spot welding of a work, a part of the melted work, which is located between the electrodes, is so-called scatter or spatter (hereinafter, collectively referred to as spatter) when welding is conducted. ) And fly around.
Part of the spatter adheres to the gun arm. When the gun arm is simply made of an aluminum alloy, the spatter may partially dissolve and adhere to the outer surface of the gun arm, and the spatter flies one after another and deposits thereon. Therefore, it is necessary to remove spatters deposited on the gun arm from time to time, and since a part of the attached spatters melts into the outer surface of the gun arm, it takes time to remove the spatters. Is declining.

When the sputter deposited on the gun arm is observed with a microscope, a massive sputter b adheres to the gun arm a as shown in FIG.
Adhered to form a sputter-deposited layer.

[0005] Sputter b is a relatively large particle when flying to the surface of the gun arm as a sputter, and has a temperature of 1200.
° C, it adheres to the gun arm surface in a lump,
Some sputters melt the gun arm surface and have strong adhesion. In addition, it is considered that the sputter c was relatively small particles and scattered from the work, and when a part of the spatter c flew to the gun arm, it was quenched in the air and changed into a dendritic shape, and attached to the surface of the gun arm. As described above, there are at least the two types of spatters described above, and if the sputters are neglected by depositing these spatters, finally, the members of the welding gun to be insulated against the gun arm may be touched. , Causing a leakage of welding current. SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a welding gun arm and a method of manufacturing the same in which spatter can be easily removed and spatter deposition can be suppressed as much as possible.

[0006]

In order to achieve the above object,
The gun arm for welding according to the present invention is characterized in that an anodic oxide film containing fine powder of a magnetic material is provided on a surface of an arm body made of an aluminum alloy. Further, the method for manufacturing a welding gun arm of the present invention is characterized in that an arm body of a welding gun arm is formed of an aluminum alloy, and a positive electrode is formed by using a treatment liquid in which fine powder of a magnetic material is mixed and dispersed in the arm body. It is characterized by performing an oxidation treatment.

[0007]

[Function] When an anodic oxide film is formed on an aluminum alloy arm body, heat resistance is improved. That is, the melting point of the anodic oxide film is as high as about 2100 ° C., while the temperature of the flying sputter is about 1200 ° C. at the highest, so that the sputter does not melt into the anodic oxide film. Further, since the anodic oxide film has a high insulating property, even if sputter is deposited, the sputter deposited layer and the arm main body are electrically insulated, and no current leak occurs.

However, since various adverse effects other than current leakage occur when sputters are deposited, it is necessary to remove the sputters when they are deposited, and it is necessary to further suppress sputter deposition. desired. Here, as shown in FIG. 3, dendritic spatter c, which is originally difficult to adhere, adheres to the gun arm, and further, sputter adheres and grows in a direction 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 sputter itself is magnetized by crossing 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. Therefore, if the magnetic field around the gun arm generated by the current supplied to the gun arm is cut off, the flying spatter will not be magnetized, and the spatter adhered by the magnetization will be eliminated.

According to the present invention, since the magnetic material is contained in the anodic oxide film on the surface of the arm main body, the surface of the gun arm becomes a magnetic layer insulated from the arm main body. The magnetic flux generated around the magnetic layer is concentrated on the magnetic layer, the magnetic field around the gun arm is weakened, and the adhesion due to the magnetization of the sputter is suppressed.

[0010] As described above, melting of spatter and adhesion due to magnetization are suppressed, and current leakage is prevented, so that it is not necessary to frequently remove spatter, and the work of removing spatter can be performed in a short time. And the operation rate of the welding gun is greatly improved.

[0011]

FIG. 1 shows a resistance spot welding gun, in which electrodes 1a and 2a are attached to tips of a pair of gun arms 1 and 2 and a work W is sandwiched between the electrodes 1a and 2a. , 2 to perform resistance spot welding of the work W.

Each of the gun arms 1 and 2 is, as shown in FIG.
An anodized film 11 was formed on the surface of an arm body 10 made of an aluminum alloy, for example, A6061P-T6.

The anodic oxide film 11 is generally formed by performing an electrolytic treatment, that is, an anodizing treatment, using the arm body 10 as an anode in a treating solution comprising an electrolytic solution containing sulfuric acid, oxalic acid or chromic acid. In the present embodiment, the fine powder of the magnetic material is mixed and dispersed in the processing liquid, and the arm body 1
The anodic oxide film 11 containing the magnetic material 12 was formed on the surface of No. 0.

According to experiments, 15 wt% of fine powder of γ-Fe ₂ O ₃ as a magnetic material and 0.03 wt% of an anionic surfactant were mixed in a treating solution containing 15 wt% of sulfuric acid. When anodizing treatment was performed using the same, as shown in FIG.
Γ-Fe ₂ O ₃ as the magnetic material 12 was eutectoid in the anodic oxide film 11.

Here, γ-Fe ₂ O ₃ is an acidic oxide which moves to the cathode side by electrophoresis. Therefore, an anionic surfactant is added, the particles of γ-Fe ₂ O ₃ are wrapped with the activator and charged negatively, and the particles of γ-Fe ₂ O ₃ are moved toward the arm body 10 as an anode. Like that. The anionic ^{_{surfactant, C 8 H 17 SO 3 -}} Na +, C 8 H 17 OSO 3 - N
^{_{a +, C 10 H 21 SO}} 3 - Na +, C 7 F 15 COO - there is such as Na ^+, the addition of 0.1% or less, preferably from 0.01 to 0.05%.

The anionic surface active agent is released from the particle surface at deprived of negative charge γ-Fe ₂ O ₃ of the arm body 10, the particles of γ-Fe ₂ O ₃ is the suction force to the arm body 10 lose. Therefore, it is necessary to increase the generation rate of the anodic oxide film 11 and to incorporate γ-Fe ₂ O ₃ into the anodic oxide film 11. Therefore, the liquid temperature is set to 20 to 25 ° C., the current density is set to be larger than the value of the normal anodic oxidation treatment (1 to ^{2 A} / dm ² ), and the film formation rate is increased. The current density is 20 A / d
When it exceeds m ² , the film density decreases and the insulating property decreases, so that the current density is 20 A / dm ² or less, preferably ^{2 to} 5 A / d
It is set to m ^2.

The amount of γ-Fe ₂ O ₃ mixed into the processing solution is 5 to 20 wt.
%, And when the treatment solution is a sulfuric acid electrolyte, the amount of sulfuric acid is desirably 10 to 20% by weight. It is also possible to use an oxalic acid electrolytic solution or a chromic acid electrolytic solution as the treatment liquid.
It is desirable that the content of chromic acid is about 3% by weight.

The anodic oxide film 11 comprises a barrier layer 11a and a porous layer 11b outside the barrier layer 11a. If necessary, the porous layer 11b may be sealed by hydration sealing. good.

As described above, when the magnetic material 12 is contained in the anodic oxide film 11, the outermost layer of each of the gun arms 1 and 2 becomes a magnetic layer, and the magnetic flux generated by energizing the gun arms 1 and 2 generates the magnetic layer. And the surrounding space is magnetically shielded with respect to the gun arms 1 and 2 so that the gun arms 1 and 2
The magnetic field around 2 becomes weaker. Therefore, the gun arm 1,
The spatters that fly to 2 are less likely to be magnetized, and sputter deposition due to magnetic attraction is suppressed.

Further, as described in the above operation, since the anodic oxide film 11 has a high melting point, the sputter solidifies without dissolving into the anodic oxide film 11, and the anodic oxide film 11 causes the sputter to solidify with the gun body 10. Since the insulating layer is electrically insulated from the deposited layer, current leakage does not occur even when the sputtered layer contacts another member.

Incidentally, the anodic oxide film 11 containing the magnetic material 12 may be formed on the entire gun arm. However, current leakage such as a portion where sputter deposition occurs, for example, a joint portion with the arm holder or an insulating portion. May be partially formed in a portion where the occurrence of the problem easily occurs, or in an electrode mounting portion at the tip of the arm that hinders electrode replacement.

[0022]

As is apparent from the above description, according to the present invention, the operation for removing the spatter can be performed in a short time and the frequency of the operation for removing the spatter can be reduced. Can be greatly 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.

FIG. 2 is a schematic sectional view of the surface of a gun arm showing an embodiment of the present invention.

FIG. 3 is a diagram showing a conventional sputter deposition state on a gun arm.

[Explanation of symbols]

 1, 2 Gun arm, 10 Arm body 11 Anodized film, 12 Magnetic material

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23K 11/00-11/36 330

Claims (2)

(57) [Claims] 1. A welding gun arm comprising: an aluminum alloy arm body having an anodic oxide film containing a fine powder of a magnetic material on a surface of an arm body made of the aluminum alloy. 2. A welding gun arm, wherein an arm body of the welding gun arm is formed of an aluminum alloy, and the arm body is subjected to anodizing treatment using a treatment liquid in which fine powder of a magnetic material is mixed and dispersed. Manufacturing method.