JPH0455062A - Electrode for plasma arc processing and production thereof - Google Patents

Abstract

PURPOSE:To prolong the service life of the electrode for plasma arc processing by freely inserting an insert body plated with nickel into the recessed part at the front end of an electrode base material and press welding the outer periphery at the end of the electrode base material in a central direction, thereby forming the end faces of both with flush with each other. CONSTITUTION:Since the insert body 3 is covered with the electroplating of Ni, the adhesive property between the Ni plating and the high melting insert body 3 is good and the plated insert body 3 is press welded into the recessed part 201 at the front end of the electrode base material 2. The stripping of the plating from the insert body 3 is not possible before the press welding or at the time of press welding. Then, the easy and sure production of the electrode 1 is possible. Further, the insert body 3 is press welded to the recessed part at the front end of the electrode base material 2 and, therefore, even if the electrode 1 is heated during plasma processing, the insert body 3 is held by the restraining force at the time of press welding and the insert body 3 is held without being disengaged. Since the N plating does not substantially form an oxide, the heat generated during the plasma processing is taken out by the cooling fluid for cooling the electrode base material and, therefore, the electrode 1 is prevented from being overheated.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Application Field The present invention relates to an electrode used in a plasma arc processing torch for welding or cutting workpieces, and a method for manufacturing the same.

<Prior Art> In general, a plasma arc processing torch is shown in FIG. 4, and 1 is a plasma electrode cooled by a fluid. The electrode base material 2 is made up of a high melting point insert 3 made of hafnium, zirconium, etc., which is attached to the recess at the tip of the electrode base material 2.

4 is an electrode support member made of a conductive material that supports the electrode 1;
5 is an insulating sleeve provided outside the electrode support member 4;
Reference numeral 6 denotes a tip support member made of a conductive material provided outside the insulating sleeve 5, and the torch body 7 is constituted by the above-mentioned 4 to 6.

8 is a hollow chip supported at the tip of the chip support member 6, and a plasma flow jetting hole 801 is bored in the center of the tip. Reference numeral 9 denotes an insulating cup, and 10 denotes a cooling water guide pipe. The cooling water that flows in from the supply hose 11 directly cools the electrode 1, and then flows out of the torch from the drain hose 12 through the passage indicated by the arrow.

In the above torch, electric power is supplied between the electrode 1 and the workpiece, and an appropriate plasma arc forming fluid G such as air, oxygen, nitrogen, etc. is supplied to the plasma jet hole 801 of the tip 8.
A plasma jet is generated by injecting the plasma jet, and the workpiece is processed using this plasma jet.

<Problems to be Solved by the Invention> However, in this type of plasma arc processing torch, even though the electrode 1 is cooled, it reaches a high temperature during processing, so hafnium or Even the electrode 1 equipped with the zirconium insert 3 had the disadvantage of a short service life.

On the other hand, the insert 3 of zirconium is immersed in molten zinc chloride to galvanize the insert 3, then dipped in the molten chain to plate the insert 3 with silver, and the zinc plating and silver plating are It has been proposed that the inserted insert 3 be brazed to the four ends of the electrode base material 2 with silver. In this case, an oxide film is formed on the surface of the galvanized plate, and because of this oxide film, heat conduction from zinc to silver is poor, the heat of the insert 3 is not quickly transferred to the electrode base material 2, and as a result, the electrode There was a drawback that the service life of No. 1 was not improved as much as expected. Furthermore, since the zinc plating applied to the insert 3 by immersing the zirconium insert 3 in molten zinc chloride easily peels off from the zirconium, it is difficult to insert the plated insert 3 into the recess at the tip of the electrode base material 2. There is a drawback in that the plating peels off when external force is applied to the plating portion of the insert 3 until the silver brazing work is completed. Furthermore, since the insert 3 becomes hot during processing, a portion of the silver plate that attaches the insert 3 to the recess at the tip of the electrode base 2 melts, and the insert 3 separates from the electrode base 3. There was also a drawback.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electrode for plasma arc processing that has an improved service life.

Means for Solving the Problems> In order to achieve the above object, the present invention has a structure in which a high melting point insert is attached to a recess at the tip of an electrode base material made of copper or copper alloy cooled by a fluid. In the electrode for plasma arc processing, the insert is sequentially electroplated with nickel and plated with a noble metal, and the diameter of the tip recess is formed to be slightly larger than the diameter of the plated insert,
The insert body is inserted into the tip recess, the outer periphery of the end of the electrode base material is crimped toward the center, and the tip part of the electrode base material and the insert body are machined so that they are flush with each other. It is characterized by

Effect> Since nickel electroplating is applied to the insert, the adhesion between the nickel plating and the insert with a high melting point such as hafnium or zirconium is good, and the peeling phenomenon of nickel plating and noble metal plating from the insert is drastically reduced. do. In addition, nickel plating does not substantially produce oxides, so
The heat generated in the insert during processing is rapidly transferred from the nickel plating to the precious metal plating to the electrode base material, and is sequentially extracted by the cooling fluid of the electrode base material, so that the electrode does not overheat beyond its predetermined state. never be done. Therefore, the life of the electrode becomes longer than before. Furthermore, because the adhesion between the nickel plating and the insert is good, even if the outer periphery of the end of the electrode base material is pressed toward the center and the insert is crimped into the recess at the tip of the electrode base material, the plating will not separate from the insert. It can be used without peeling. Furthermore, since the insert is crimped into the recess at the tip of the electrode base material, even if the electrode is heated, the insert is held by the restraining force during crimping, and there is no risk of the insert becoming detached.

<Example> Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

In FIGS. 1(A) to 81(F) and FIGS. 2(A) to 2(D), 3 is a high melting point insert formed to a predetermined size, for example, this insert 3 is , diameter 1-3
■It is formed into a cylindrical shape with a m1 length of 3 to 51 m. First, the surface of the insert 3 is degreased and the oxide film is removed by pretreatment such as electrolytic degreasing and immersion in hydrofluoric acid. Thereafter, nickel plating 41 is applied to the surface of the insert 3 by electroplating, as shown in FIG. 1(B).

For example, the insert 3 is electroplated with nickel using a wood strike bath. In this case, the current density of wood strike nickel plating is 1 to 10 A*dm-2, preferably 2 to 4 A-dm-2, and the electroplating time is 10 to 10 A*dm-2.
By setting the time to 5 minutes, an appropriate thickness of the wood strike nickel plating 41 of 0.1 to 20 μm was obtained. Thereafter, as shown in FIG. 1(C), silver plating 42 is applied to the surface of the insert 3 as appropriate. The insert 3 is thus sequentially electroplated with nickel 41 and silver 42.
When the diameter of the tip is d, the diameter of the tip recess 201 formed in the electrode base material 2 made of copper or copper alloy is slightly large, d + Δd, and the insert 3 is inserted into the tip recess 201.
to enter. Thereafter, as shown in FIG. 1(E) and FIG. 2(A), the electrode base material 2 is
Crimp the outer circumference of the end toward the center. Incidentally, during crimping, the electrode base material 2 protrudes beyond the end surface of the insert 3 to the tip of the electrode 1. Electrode 1 with this protrusion 202 still formed
When used for plasma arc processing, the arc generation point on the electrode surface crawls over the protrusion 202, which warps and shortens the life of the electrode. For this reason, Figure 1 (F)
As shown in FIG. 2, after crimping, the protrusion 202 is removed by machining such as cutting with a cutting tool or a grinder in the next step, and the tip of the electrode base material 2 and the insert body 3 are removed.
are formed so that they are flush with each other.

In this way, since the tip of the electrode base material 2 and the insert 3 are formed flush with each other, the arc generation point on the electrode surface is on the insert 3, and plasma processing is performed in a desired state.

In the electrode manufactured as described above, since nickel electroplating is applied to the insert 3, the nickel plating 41
The adhesion between the insert 3 and the high-melting-point insert 3 made of hafnium is good, and the insert 3 has a good adhesion before the step of crimping the plated insert 3 into the tip recess 201 of the electrode base material 2. Even if an unexpected external force is applied to the plating part, the plating hardly peels off, and since the adhesion between the nickel plating 41 and the insert 3 is good, the electrode base material 2 Even if the outer periphery of the end portion is pressed toward the center, the plating does not peel off from the insert 3, and therefore the insert 3 can be reliably crimped into the tip recess 201 of the electrode base material 2. That is, the plasma electrode 1 can be manufactured easily and reliably.

Furthermore, when using the plasma electrode 1, since the insert 3 is crimped into the tip recess 201 of the electrode base material 2, even if the electrode 1 is heated, the insert 3 is held by the binding force during crimping, and the insert 3 is Since the insert 3 does not come off and the nickel plating 41 does not substantially generate oxides, the heat generated in the insert 3 during plasma processing is absorbed by the nickel plating 4.
1 - Silver plating 42 - Rapidly transmitted to the electrode base material 2,
Since the electrode base material 2 is sequentially drawn out of the electrode 1 by the cooling fluid that cools it, the electrode 1 is not overheated beyond a predetermined state. Therefore, the life of the electrode becomes longer than before.

FIG. 3 is a diagram showing the life of an electrode, in which the case of a conventional electrode (A) using hafnium as an insert is shown by the dotted line, and the case of an insert sequentially coated with zinc plating and silver plating is shown as an electrode base. The case of the conventional electrode (b) whose material is soldered with silver is shown by a dashed line, and the case of the electrode according to the present invention is shown by a solid line. As can be understood from FIG. 3, the electrode according to the present invention has a service life that is more than 30% longer than that of the improved conventional electrode (b).

Plasma cutting conditions in Figure 3 Cutting speed: 40 cm/*InO cutting length: 30C1l/times Current: 12OA Material to be cut: 5S41. Plate thickness: 16 fins Cutting time per cut: 45 seconds Figures 2 (A) to 2 (D) show crimping methods used when crimping the outer periphery of the end of the electrode base material 2 toward the center. FIG. 2(B) is a diagram showing a modification of the tools 51 to 54;
As shown in FIG. 2(D), if a crimping surface parallel to the outer surface of the electrode 1 is formed after crimping, this parallel crimping surface can be used as a tool locking surface for attaching and detaching the electrode. Therefore, the tool locking surface machining process after crimping can be omitted, and the electrode 1 can be manufactured at low cost. The insert 3 can also be made of zirconium.

In the above, a wood strike bath is most suitable for electroplating the insert 3 with nickel. Despite this, if conditions such as plating speed and adhesion of nickel plating to the insert can be reduced to a certain degree, appropriate electroplating such as sulfamic acid bath or Watt bath may be used. can.

Furthermore, it is best to plate the insert 3 electroplated with nickel with silver in terms of heat conduction and cost, but plating with so-called noble metals such as gold, platinum, or rhodium is also possible.

<Effects of the Invention> As is clear from the above explanation, in the electrode for plasma arc processing according to the present invention, nickel electroplating is applied to the insert, so that the nickel plating and the high melting point insert are in close contact with each other. The electrode has good properties, and the plating does not peel off from the insert until and during the crimping of the plated insert into the recess at the tip of the electrode base material. Therefore, the electrode can be manufactured easily and reliably. I can do it. Furthermore, since the insert is crimped into the recess at the tip of the electrode base material, even if the electrode is heated during plasma processing, the insert will be held by the binding force during crimping and will not come off. , nickel plating produces virtually no oxides, so the heat generated on the insert during plasma processing is reduced by nickel plating →
The silver plating is quickly transferred to the electrode base material, and is sequentially taken out to the outside of the electrode 5 by the cooling fluid that cools the electrode base material, so that the electrode is not overheated beyond a predetermined state.

Therefore, the life of the electrode becomes longer than before.

[Brief explanation of the drawing]

FIG. 1(A) to FIG. 1(F) are longitudinal sectional views for explaining the manufacturing state of the electrode for plasma arc processing of the present invention;
FIG. 2(A) to FIG. 2(D) correspond to the side view of FIG. 1(E), each showing a different embodiment, and FIG. 3 is a drawing showing the electrode life, where the solid line is In the case of the present invention, the dotted line and the dashed-dotted line are diagrams showing the conventional case, respectively, and FIG. 4 is a sectional view of the main part of a general plasma arc processing torch. Figure 1 (D) Figure 1 (E) 1... Electrode, 2... Electrode base material, 3... Insert first
Figure (C) Figure 1 (F)

Claims (1)

[Claims] 1. An electrode for plasma arc machining in which a high-melting point insert is attached to a recess at the tip of an electrode base material made of copper or copper alloy cooled by a fluid, wherein the insert has a nickel electrode. Plating and noble metal plating are sequentially applied, the diameter of the tip recess is formed to be slightly larger than the diameter of the plated insert, the insert is loosely inserted into the tip recess, and the electrode base material is plated. An electrode for plasma arc machining, the outer periphery of the end being crimped toward the center, and machined so that the tip of the electrode base material and the insert are flush with each other. 2. In a plasma arc processing electrode in which a high-melting point insert is attached to a recess at the tip of an electrode base material made of copper or copper alloy cooled by a fluid, the insert is electroplated with nickel and plated with a noble metal. The diameter of the tip recess is formed to be slightly larger than the diameter of the plated insert, the insert is loosely inserted into the tip recess, and the outer periphery of the end of the electrode base material is moved toward the center. A method of manufacturing an electrode for plasma arc processing, which comprises crimping the electrode base material and machining it so that the tip of the electrode base material and the insert body are flush with each other.