JP2004167535A - Method and apparatus for regenerating electrode tip for spot welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for regenerating an electrode tip for spot welding in which the same electrode tip for spot welding can be regenerated and used for many times, also, the regeneration process is simple and inexpensive, and cut powder or the like are not produced as well. <P>SOLUTION: The apparatus for regenerating an electrode tip for spot welding consisting of copper or a copper alloy, and in which a degenerated layer of a base metal is formed on the surface of an electrically conducting head is provided with a forming die body 31 in which a hole 31a for forming having a prescribed shape and also having a specular inside face is formed, and a forming die 30 with a structure where the forming die body 31 is reinforced by a die support ring 32. High pressure is applied to the electrode tip 15 for spot welding inserted into the hole 31a for forming in the forming die 30 and freed from the degenerated layer of the base metal on the surface of the electrically conducting head, and the electrode tip 15 for spot welding is penetrated into the hole 31a for forming, and is thus formed into a prescribed shape. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for regenerating a spot welding electrode tip used for spot electric welding.
[0002]
[Prior art]
For example, in an automobile manufacturing plant or the like, spot electric welding is often used to connect a metal plate such as an iron plate to a metal plate. This spot electric welding includes an upper electrode 11 and a lower electrode 12 as shown in FIG. 1 and has an electrode holder 13 fixed to the upper electrode 11 and a sub holder 14 attached to the electrode holder 13. , And an electrode tip 15 is attached to the tip of the sub-holder 14. An electrode holder 16 is fixed to the lower electrode 12, a sub-holder 17 is attached to the electrode holder 16, and an electrode chip 15 is attached to a tip of the sub-holder 17.
[0003]
Then, the joint between the metal plate 19 and the metal plate 20 such as an iron plate located between the upper and lower electrode chips 15 and 15 is pressurized (for example, 270 kg) by the electrode chips 15 and 15 to generate a large current (for example, 9800 amperes). Is applied in tens of cycles (for example, 12 cycles), and the joint between the metal plate 19 and the metal plate 20 is spot-welded. The electrode tips 15, 15 are usually made of copper or a copper alloy (for example, chromium copper). When such welding work is repeated, the current-carrying head wears and a deteriorated layer of the base material is formed on the surface, and about 100 dots are formed. As shown in FIG. 2, a deteriorated layer (black scorch mark due to oxidation or the like) 21 of the base material is formed on the surfaces of the current-carrying heads of the electrode tips 15 and 15.
[0004]
When the deteriorated layer 21 of the base material is formed on the current-carrying head surfaces of the electrode tips 15 and 15 as described above, the electric resistance increases, the current-carrying capacity deteriorates, and the welding capacity decreases. Therefore, conventionally, as shown in FIG. 2, the surface layer portion of the electrode tip 15 including the deteriorated layer 21 has been cut off (cut off outside of the dashed line A in FIG. 2) by a cutting process to form the electrode tip into a predetermined shape. As described above, the conventional method for regenerating an electrode tip also removes a portion of the base material that has not been deteriorated. Therefore, when the reproduction is repeated, the base material is worn as shown by dashed lines B and C in FIG. Therefore, the number of reproductions is limited to about 6 to 7 times. Therefore, the amount of the electrode tip used for spot electric welding is large, which has caused the cost of spot electric welding to increase. In addition, a large amount of powder chips and the like are generated from the electrode tips, and there is a problem that the treatment is difficult.
[0005]
[Patent Document 1]
JP-A-63-137586
[Problems to be solved by the invention]
The present invention has been made in view of the above points, and it is possible to regenerate the same spot welding electrode tip and use the electrode tip many times, and it is also easy and inexpensive to regenerate the spot electrode, and furthermore, spot welding which does not generate dust and the like. It is an object of the present invention to provide a method and apparatus for reproducing electrode chips for use.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 is a method for regenerating a spot welding electrode tip made of copper or a copper alloy in which a deteriorated layer of a base material is formed on the surface of a current-carrying head, After the altered layer is removed, the spot welding electrode tip from which the altered layer has been removed is formed into a predetermined shape by a cold forging press method.
[0008]
After removing the deteriorated layer of the base metal on the surface of the current-carrying head of the electrode tip for spot welding as described above, it is formed into a predetermined shape by the cold forging press method, so regeneration can be performed by only removing the deteriorated layer of the base material. It is possible to minimize the wear rate due to the regeneration of the electrode tip for spot welding, and to greatly increase the number of times of regeneration of the electrode tip for spot welding, greatly improving the life of the electrode tip for spot welding. I do.
[0009]
According to a second aspect of the present invention, in the method for regenerating the electrode tip for spot welding according to the first aspect, the removal of the altered layer of the base material is performed by chemical polishing using a chemical abrasive.
[0010]
Since the altered layer of the base material is removed by chemical polishing using a chemical polishing agent as described above, the altered layer of the base material of a large number of spot welding electrode tips can be removed at once, and the spot welding electrode can be formed at low cost. Reproduction of chips becomes possible.
[0011]
According to a third aspect of the present invention, in the method for regenerating an electrode tip for spot welding according to the first or second aspect, the chemical abrasive is a chemical abrasive mainly containing sulfuric acid and hydrogen peroxide. And
[0012]
The chemical polishing agent containing sulfuric acid and hydrogen peroxide as main components is a chemical polishing agent used for pretreatment of a plating treatment of a copper product or a copper compound, and can safely and reliably remove a deteriorated layer of a base material. In addition, the treatment of waste liquid has been established, and the impact on the environment is small.
[0013]
An invention according to claim 4 is an apparatus for regenerating a spot welding electrode tip made of copper or a copper alloy having a deteriorated layer of a base material formed on the surface of a current-carrying head, wherein the apparatus has a predetermined shape and an inner surface having a mirror surface. A forming die body having a hole formed therein, and a forming die having a structure in which the outer periphery of the forming die body is reinforced with a die support ring, and a base material of the surface of the current-carrying head inserted into the forming hole of the forming die. It is characterized by comprising a pressurizing means for applying high pressure to the electrode tip for spot welding from which the deteriorated layer has been removed and pushing it into the hole for forming to form the electrode tip for spot welding into a predetermined shape.
[0014]
Conventionally, this type of die has a structure in which the die is formed in a predetermined shape and the inner surface is formed with a mirror-forming hole as described above, and the outer periphery of the die is reinforced with a die support ring. When a product made of copper or a copper alloy was to be formed by the forging press method, there was a problem that the forming die was cracked. Here, the inner surface of the forming hole of the forming die body was made a mirror surface, and the outer periphery of the die body was formed. Is reinforced by the die support ring, so that the forming die is not broken by the indentation forming, and the electrode tip for spot welding can be regenerated inexpensively.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 4 is a diagram showing a configuration example of a reproducing apparatus of the electrode tip for spot welding according to the present invention. In FIG. 4, reference numeral 31 denotes a forming die main body. The forming die main body 31 is made of a HAP material, and has a predetermined shape forming hole 31a for forming an electrode tip for spot welding. After the forming hole 31a is formed by electric discharge machining, the inner surface is mirror-finished by lapping. Further, the outer periphery of the forming die body 31 is reinforced by a die support ring 32. This is configured by shrink-fitting the die support ring 32 to the molding die body 31.
[0016]
A forming die 30 formed by reinforcing the outer periphery of the forming die body 31 with a die support ring 32 is fixed on a die plate 33, and the die plate 33 is fixed to an apparatus base 35. The forming die body 31 and the die plate 33 are formed with through holes 31b and 33a through which the lifter pins 34 pass. The lifter pins 34 are attached to the tops of the lifters 36, and the lifter amount D1 (for example, 5.0 mm). ) Can be moved up and down.
[0017]
37 is a forming punch, and 38 is a knockout pin. The forming punch 37 is made of die steel and is attached to a pressing table 39. The knockout pin 38 passes through a through hole 37 a formed in the center of the forming punch 37, and is pressed by a coil spring 40. D2 is a knockout amount (for example, 5.0 mm).
[0018]
In the apparatus for regenerating the electrode tip for spot welding having the above-described configuration, the electrode tip 15 for spot welding in which the deteriorated layer of the base material on the surface of the current-carrying head is removed by chemical polishing using a chemical abrasive as described in detail below. By inserting the knockout pin 38 and the forming punch 37 thereon, applying a high load to the forming punch 37 and pushing the spot welding electrode tip 15 into the forming hole 31a of the main body 31, , Copper or a copper alloy (for example, chromium copper) is press-formed into the shape of the forming hole 31a.
[0019]
Conventionally, when such a rod-shaped product made of copper or a copper alloy is inserted into a forming hole of a forming die, and then pressed and formed, the forming die is broken. The forging press method was difficult. Here, a forming hole 31a is formed in the forming die body 31 made of the HAP material, and the inner surface thereof is mirror-finished by lapping, and a die support ring 32 made of S45C material is shrink-fitted on the outer periphery of the forming die body 31. Since it is attached and reinforced, the surface of the electrode tip 15 for spot welding can be formed into the inner surface shape of the forming hole 31a without breaking the forming die body 31.
[0020]
As described above, in the spot electric welding, when the welding operation is repeated, the deteriorated layer 21 of the base material is formed on the surface of the current-carrying head of the electrode tip 15 at about 100 spots as shown in FIG. Therefore, here, the altered layer 21 is removed by chemical polishing using a chemical polishing agent. By adopting the removal method by chemical polishing as described above, it is possible to effectively remove only the deteriorated layer 21 of the base material on the surface of the electrode tip 15. As the chemical abrasive, for example, a chemical abrasive of copper and a copper compound containing sulfuric acid and hydrogen peroxide as main components is used. An example of such a chemical polishing agent is "Hybright" manufactured by Nippon Peroxide Co., Ltd. The electrode tip 15 for spot welding, in which the deteriorated layer 21 of the base material is formed on the surface of the current-carrying head, is immersed in such a solution of the chemical polishing agent. After the deteriorated layer 21 is removed, the chemical polishing agent is removed by washing with water or the like. I do.
[0021]
FIGS. 5A, 5B, and 5C are views showing a regeneration step in the case of regenerating a spot welding electrode tip having a diameter of 16 mm by the apparatus for regenerating a spot welding electrode tip according to the present invention. 5A, the electrode tip 15 for spot welding from which the altered layer of the base material has been removed by chemical polishing is inserted into the forming hole 31a of the forming die body 31. The diameter Φ at the top of the electrode tip 15 for spot welding from which the altered layer has been removed by this chemical polishing is Φ = 8 mm. When this is inserted to the bottom of the forming hole 31a as shown in FIG. 5 (b), the outer periphery (Φ = 8 mm) of the top of the electrode tip 15 for spot welding comes into contact with the inner wall surface of the forming die body 31 and the spot welding is performed. A gap d is formed between the top of the electrode tip 15 and the bottom of the forming hole 31a. In this state, the electrode tip 15 for spot welding is sandwiched between the lifter pin 34 and the knockout pin 38.
[0022]
When a high load is applied to the forming punch 37 and the spot welding electrode tip 15 is pushed in, the outer peripheral portion of the head is pressed against the wall surface of the forming hole 31a, and as shown in FIG. It is pushed in until the bottom wall surface and the outer peripheral surface of the head of the spot welding electrode tip 15 are in close contact with each other, and the outer diameter of the head is Φ = 6 mm, and the head is reproduced.
[0023]
As described above, in the method of regenerating the electrode tip for spot welding according to the present invention, the altered layer of the base material is removed by chemical polishing using a chemical abrasive, so that the base material other than the altered layer 21 shown in FIG. 2 is removed. Therefore, the amount of wear of the electrode tip 15 for spot welding is small. Further, since the spot welding electrode tip 15 from which the altered layer 21 has been removed is formed by a cold forging method, a conventional method of cutting and removing a base material portion necessary for a molded portion including the altered layer 21 as in the related art is used. The amount of electrode wear is extremely small as compared with
[0024]
For example, if an electrode tip for spot welding of Φ = 16 mm is taken as an example, the conventional regenerating method by cutting can only regenerate about 6 to 7 times, but the regenerating method according to the present invention can regenerate about 26 to 28 times. Reproduction is possible. Also, after removing the deteriorated part of the base material of the energized head of many spot welding electrode tips at a time by chemical polishing, it is formed by cold forging press method, so it is compared with the conventional individual cutting process Reproduction processing cost can be reduced.
[0025]
Although the method of removing the deteriorated layer 21 of the base material of the electrode tip 15 for spot welding by chemical polishing has been described in the above embodiment, any method that can effectively remove only the deteriorated layer 21 of the base material can be used. The present invention is not limited to the chemical polishing. For example, after the altered layer 21 at the top is cut and removed, it may be formed by a cold forging press using the forming die 30 as described above.
[0026]
【The invention's effect】
As described above, according to the invention described in each claim, the following excellent effects can be obtained.
[0027]
According to the first aspect of the present invention, after the deteriorated base material layer on the surface of the current-carrying head of the electrode tip for spot welding is removed, it is formed into a predetermined shape by the cold forging press method, so only the deteriorated layer of the base material is formed. It is possible to regenerate by simply removing the spot welding electrode, reducing the wear rate by regenerating the spot welding electrode tip as much as possible, and greatly improving the number of times of regenerating the spot welding electrode tip. The life of the chip is greatly improved. In addition, since the regeneration process is performed by the cold forging press method, the regeneration cost can be significantly reduced as compared with the regeneration by the conventional cutting process.
[0028]
According to the invention as set forth in claim 2, since the altered layer of the base material is removed by chemical polishing using a chemical polishing agent, it is possible to remove the altered layer of the base material of a large number of spot welding electrode tips at once, It is possible to regenerate the electrode tip for spot welding at low cost.
[0029]
According to the third aspect of the present invention, since a chemical polishing agent containing sulfuric acid and hydrogen peroxide as main components is used, the chemical polishing agent is used for a chemical polishing used for a pretreatment of a plating treatment of a copper product or a copper compound. It is an agent that can safely and reliably remove the altered layer of the base material. In addition, the treatment of waste liquid has been established, and the impact on the environment is small.
[0030]
According to the invention as set forth in claim 4, the forming die has a structure in which a forming die body having a predetermined shape and a mirror-finished inner surface is formed, and the outer periphery of the forming die body is reinforced by a die support ring. Conventionally, when a product made of copper or a copper alloy of this type was to be formed by a forging press method, there was a problem that a forming die was broken, but here, an inner surface of a forming hole of a forming die body is made a mirror surface. At the same time, since the outer periphery of the die body is reinforced by the die support ring, the forming die is not broken by the press forming, and a reproducing apparatus capable of reproducing the electrode tip for spot welding at low cost can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of spot electric welding.
FIG. 2 is a cross-sectional view showing a spot welding electrode tip in which a deteriorated layer of a base material is formed on a current-carrying head by performing a spot welding operation.
FIG. 3 is a view showing a conventional method for regenerating a spot welding electrode tip by cutting.
FIG. 4 is a diagram showing a configuration example of a reproducing apparatus of an electrode tip for spot welding according to the present invention.
FIG. 5 is a view showing a step of regenerating the electrode tip for spot welding according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Upper electrode 12 Lower electrode 13 Electrode holder 14 Subholder 15 Electrode chip 16 Electrode holder 17 Subholder 19 Metal plate 20 Metal plate 21 Altered layer 30 Molding die 31 Molding die main body 32 Dice support ring 33 Die plate 34 Lifter pin 35 Machine stand 36 lifter 37 forming punch 38 knockout pin 39 press table 40 coil spring

Claims (4)

A method for regenerating a spot welding electrode tip made of copper or a copper alloy in which a deteriorated layer of a base material is formed on a surface of a current-carrying head,
A method for regenerating a spot welding electrode tip, comprising: removing a deteriorated layer of the base material; and forming the spot welding electrode tip from which the deteriorated layer has been removed into a predetermined shape by a cold forging press method. The method for regenerating an electrode tip for spot welding according to claim 1,
The method for regenerating an electrode tip for spot welding, wherein the removal of the altered layer of the base material is performed by chemical polishing using a chemical polishing agent. The method for regenerating a spot welding electrode tip according to claim 1 or 2,
The method for regenerating an electrode tip for spot welding, wherein the chemical polishing agent is a chemical polishing agent containing sulfuric acid and hydrogen peroxide as main components. A regeneration device for an electrode tip for spot welding made of copper or a copper alloy in which a deteriorated layer of a base material is formed on a surface of a current-carrying head,
A molding die body having a predetermined shape and an inner surface formed with a mirror surface molding hole, and a molding die having a structure in which the outer periphery of the molding die body is reinforced with a die support ring,
A high pressure is applied to the electrode tip for spot welding, in which the deteriorated layer of the base material on the surface of the current-carrying head inserted into the molding hole of the molding die is removed, and the electrode tip for spot welding is pushed into the hole for molding. An apparatus for regenerating an electrode tip for spot welding, comprising a pressurizing means for forming into a predetermined shape.

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