JP3763813B2 - Method for regenerating electrode tip for spot welding - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for regenerating an electrode tip for spot welding used for spot electric welding.
[0002]
[Prior art]
For example, in an automobile manufacturing factory or the like, spot electric welding is often used to connect a metal plate such as an iron plate and the metal plate. As shown in FIG. 1, the spot electric welding includes an upper electrode 11 and a lower electrode 12. An electrode holder 13 is fixed to the upper electrode 11, and a sub-holder 14 is attached to the electrode holder 13. Further, 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 tip 15 is attached to the tip of the sub-holder 17.
[0003]
The joint between the metal plate 19 such as an iron plate and the metal plate 20 located between the upper and lower electrode tips 15 and 15 is pressurized (for example, 270 kg) with the electrode tips 15 and 15 to generate a large current (for example, 9800 amperes). Is energized in ten or more 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 and 15 are usually made of copper or a copper alloy (for example, chrome copper), and when such welding operation is repeated, the current-carrying head is worn and an altered layer of the base material is formed on the surface. As shown in FIG. 2, an altered layer (black scorch mark due to oxidation or the like) 21 of the base material is formed on the current-carrying head surfaces of the electrode tips 15 and 15.
[0004]
As described above, when the altered layer 21 of the base material is formed on the surface of the current-carrying heads of the electrode tips 15 and 15, the electrical resistance increases, the current-carrying ability is deteriorated, and the welding ability is lowered. Therefore, conventionally, as shown in FIG. 2, the surface layer portion of the electrode tip 15 including the altered layer 21 is scraped off (the portion outside the one-dot chain line A in FIG. 2 is scraped) to form the electrode tip into a predetermined shape. As described above, since the conventional method of regenerating the electrode tip also removes the unmodified part of the base material, if the regeneration is repeated, the base material is worn out as shown by alternate long and short dashed lines B and C in FIG. Therefore, the number of reproductions is limited to about 6 to 7 times. For this reason, the amount of electrode tips used for spot electric welding is large, which increases the cost of spot electric welding. Further, a large amount of electrode chip dust and the like are generated, and there is a problem that the processing is difficult.
[0005]
[Patent Document 1]
JP-A-63-137586 [0006]
The present invention has been made in view of the above points. Spot welding can be performed by regenerating the same electrode tip for spot welding and using it a number of times, and can be easily and inexpensively regenerated, and further free from generation of dust and the like. An object of the present invention is to provide a method for regenerating an electrode tip 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 a current- carrying head surface by energization of electric welding. Te, a large number of spot welding electrode tip already used the altered layer is formed of the base material due to energization of the electric welding current head surface immersed in a solution of a chemical abrasive, affected layer of the base material by chemical polishing After removing the attached chemical abrasive by washing, the spot welding electrode chip from which the altered layer of the base material has been removed is individually molded into a predetermined shape by a cold forging press method. To do.
[0008]
Since the deteriorated layer of the base material on the surface of the current-carrying head of the electrode tip for spot welding is immersed in a chemical abrasive solution as described above, the deteriorated layer is removed, and then formed into a predetermined shape by a cold forging press method. It is possible to regenerate only by removing the deteriorated layer of the base material, and the consumption rate due to the regeneration of the electrode tip for spot welding can be reduced as much as possible, and the number of regenerations of the electrode tip for spot welding can be greatly improved. It becomes possible, and the lifetime of the electrode tip for spot welding can be improved significantly. In addition, a large number of used spot welding electrode tips are immersed in a chemical abrasive solution to remove the deteriorated layer of the base material. Can be realized at low cost.
[0011]
The invention according to claim 2 is the method for regenerating a spot welding electrode tip according to claim 1, wherein the chemical abrasive is a chemical abrasive mainly composed of sulfuric acid and hydrogen peroxide. .
[0012]
The chemical abrasive mainly composed of sulfuric acid and hydrogen peroxide is a chemical abrasive used for the pretreatment of the copper product or copper compound plating process, and can safely and reliably remove the altered layer of the base material. In addition, waste liquid treatment has been established, and there is little impact on the environment.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 is a diagram showing a configuration example of a spot welding electrode tip regenerating apparatus 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. The forming hole 31a is formed by electric discharge machining, and then the inner surface is finished to a mirror surface by lapping finish. Further, the outer periphery of the forming die main body 31 is reinforced by a die support ring 32. This is formed by shrink-fitting the die support ring 32 to the forming die body 31.
[0016]
A forming die 30 formed by reinforcing the outer periphery of the forming die main body 31 with a die support ring 32 is fixed on a die plate 33, and the die plate 33 is fixed on an apparatus base 35. The molding 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 top of the lifter 36, and the lifter amount D1 (for example, 5.0 mm). ) Can be moved up and down.
[0017]
37 is a molding punch, and 38 is a knockout pin. The forming punch 37 is made of die steel and is attached to a pressure table 39. The knockout pin 38 passes through a through hole 37 a formed in the center portion of the molding punch 37 and is pressed by a coil spring 40. D2 is a knockout amount (for example, 5.0 mm).
[0018]
In the spot welding electrode tip regenerating apparatus having the above-described configuration, the spot welding electrode tip 15 from which the altered 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 later is formed into a die. By inserting into the molding hole 31a of the main body 31, placing the knockout pin 38 and the molding punch 37 thereon, applying a high load to the molding punch 37, and pushing the spot welding electrode tip 15 into the molding hole 31a. The electrode tip 15 for spot welding made of copper or copper alloy (for example, chromium copper) is pressure-formed into the shape of the forming hole 31a.
[0019]
Conventionally, when a rod-shaped product made of copper or a copper alloy is inserted into a forming hole of a forming die and press-molding is performed, the forming die is cracked. The forging press method was difficult. Here, a molding hole 31a is formed in a molding die body 31 made of HAP material, the inner surface thereof is finished to a mirror surface by lapping, and a die support ring 32 made of S45C material is shrink-fitted on the outer periphery of the molding die body 31. Since it is attached and reinforced, the surface of the spot welding electrode tip 15 can be formed into the shape of the inner surface of the forming hole 31a without breaking the forming die main body 31.
[0020]
In the spot electric welding as described above, when the welding operation is repeated, the altered layer 21 of the base material is formed on the surface of the current-carrying head of the electrode tip 15 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 in this way, it becomes possible to effectively remove only the altered layer 21 of the base material on the surface of the electrode tip 15. As the chemical polishing agent, for example, a chemical polishing agent of copper and a copper compound mainly containing sulfuric acid and hydrogen peroxide is used. An example of such a chemical abrasive is “Hybright” manufactured by Nippon Peroxide Co., Ltd. The electrode tip 15 for spot welding having a base material altered layer 21 formed on the current-carrying head surface is immersed in such a chemical abrasive solution, and after removing the altered layer 21, the chemical abrasive is removed by washing with water or the like. To do.
[0021]
FIGS. 5A, 5B, and 5C are views showing a regeneration process when a spot welding electrode tip of Φ = 16 mm is reproduced by the spot welding electrode tip regeneration device according to the present invention. As shown in FIG. 5A, the spot welding electrode tip 15 from which the altered layer of the base material has been removed by chemical polishing is inserted into the molding hole 31 a of the molding die body 31. The diameter Φ of the top of the spot welding electrode tip 15 from which the deteriorated 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. 5B, the outer periphery (Φ = 8 mm) of the top of the spot welding electrode tip 15 comes into contact with the inner wall surface of the forming die body 31, and A gap d is formed between the top of the electrode tip 15 and the bottom surface of the molding hole 31a. In this state, the spot welding electrode tip 15 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 pushed 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 electrode tip 15 for spot welding are in close contact with each other, and the outer diameter of the head becomes Φ = 6 mm.
[0023]
As described above, in the method for regenerating a spot welding electrode tip according to the present invention, since the altered layer of the base material is removed by chemical polishing using a chemical abrasive, the base material other than the altered layer 21 shown in FIG. 2 is removed. Therefore, the wear amount of the spot welding electrode tip 15 is small. Further, since the spot welding electrode tip 15 from which the deteriorated layer 21 has been removed is formed by a cold forging method, a method of cutting and removing the base material portion necessary for the forming portion including the deteriorated layer 21 as in the prior art. Compared to the above, the amount of electrode wear is extremely small.
[0024]
For example, if an electrode tip for spot welding with Φ = 16 mm is shown as an example, the reproduction method by the conventional cutting process can only reproduce about 6 to 7 times, but the reproduction method according to the present invention makes about 26 to 28 times. Playback is possible. In addition, after removing the base material alteration part of the current-carrying head of many electrode tips for spot welding at a time by chemical polishing, it is formed by cold forging press method, so compared with the regeneration by conventional individual cutting process Reproduction costs can be reduced.
[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 invention described in claim 1, after the deteriorated layer of the base material on the surface of the current-carrying head of the electrode tip for spot welding is immersed in a solution of a chemical abrasive and removed, the cold forging press method by so formed into a predetermined shape, it is possible to reproduce only by removing only affected layer of the base material, it is possible to minimize reduce consumption due to regeneration of the electrode tip for spot welding, the number of plays of the electrode tip for spot welding It becomes possible to greatly improve, and the life of the electrode tip for spot welding is greatly improved. In addition, a large number of used spot welding electrode tips are immersed in a chemical abrasive solution to remove the deteriorated layer of the base material. Can be realized at low cost. Further, since the altered layer of the base material is removed by chemical polishing and the reclaiming process is performed by the cold forging press method, the reworking cost can be greatly reduced as compared with the regeneration by the conventional cutting process. Further, since no dust is generated when the deteriorated layer of the base material is removed, a large amount of powder is not generated even when a large amount of used electrode tips for spot welding is regenerated, and there is no problem in processing.
[0029]
According to the second aspect of the present invention, since the chemical polishing agent mainly composed of sulfuric acid and hydrogen peroxide is used, the chemical polishing agent is used for the pretreatment of the copper product or the copper compound plating treatment. It is an agent, and the altered layer of the base material can be removed safely and reliably. In addition, waste liquid treatment has been established, and there is little impact on the environment.
[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 an altered layer of a base material is formed on a current-carrying head after performing spot welding work.
FIG. 3 is a diagram showing a method for regenerating an electrode tip for spot welding by conventional cutting.
FIG. 4 is a diagram showing a configuration example of a spot welding electrode tip regeneration apparatus according to the present invention.
FIG. 5 is a view showing a regeneration process of an electrode tip for spot welding according to the present invention.
[Explanation of symbols]
11 Upper electrode 12 Lower electrode 13 Electrode holder 14 Sub holder 15 Electrode chip 16 Electrode holder 17 Sub holder 19 Metal plate 20 Metal plate 21 Altered layer 30 Molding die 31 Molding die body 32 Die support ring 33 Die plate 34 Lifter pin 35 Device base 36 Lifter 37 Molding punch 38 Knockout pin 39 Pressurizing base 40 Coil spring

Claims (2)

A method for regenerating an electrode tip for spot welding made of copper or a copper alloy in which a deteriorated layer of a base material is formed by energization of electric welding on the surface of the energization head,
A large number of used electrode tips for spot welding, in which a deteriorated layer of a base material is formed on the surface of the current-carrying head by electrical welding, are immersed in a chemical abrasive solution, and the deteriorated layer of the base material is formed by chemical polishing. After removing the chemical abrasive that is removed by washing and cleaning, the spot welding electrode chip from which the altered layer of the base material has been removed is individually molded into a predetermined shape by a cold forging press method. A method for regenerating an electrode tip for spot welding.   2. The method for regenerating a spot welding electrode tip according to claim 1, wherein the chemical abrasive is a chemical abrasive mainly composed of sulfuric acid and hydrogen peroxide. .

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