JP2859299B2 - Torch for plasma processing - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing torch for processing a workpiece by a plasma arc.

[Prior Art] Generally, a plasma processing torch is cut and welded by a plasma arc generated between an electrode and a workpiece in an atmosphere of a working gas injected from a tip orifice of the tip. , Used for processing such as thermal spraying.

FIG. 1 shows an example of this type of plasma processing torch. The torch head 1 has an electrode 2, an electrode holder 3,
It is composed of a gas distributor 4, a chip 5, a shield cup 6, and the like. Then, the workpiece 7 is processed by a plasma arc current appropriately supplied between the electrode 2 and the workpiece 7. Reference numeral 8 denotes a plasma arc generated between the electrode 2 and the workpiece 7.

5a is a tip orifice for injecting the working gas Ga, and 6a is a cooling gas between the tip 5 and the shield cup 6.
Gb emission hole. Reference numeral 2a denotes a high-melting-point electrode material such as hafnium or zirconium, which is attached to the tip of the electrode 2.

By the way, in this plasma processing, a relatively high voltage for maintaining the plasma arc 8 is applied between the electrode 2 and the workpiece 7. The central portion 2a of the electrode 2, which is the portion where the plasma arc 8 is generated, is exposed to high temperatures,
When ordinary copper or copper alloy is used as the electrode member, it is not practical because of heavy consumption. Therefore, in general, a high-melting-point electrode material such as hafnium or zirconium is used for this portion to solve the above problem. on the other hand,
Conventionally, a copper member has been used as a chip material of the chip 5 for narrowing the plasma arc 8, and thus the following inconvenience has occurred. In FIG. 2, the plasma arc 8, which should flow directly from the electrode 2 to the workpiece 7, often flows through the tip 5. When the tip 5 comes too close to or comes into contact with the workpiece 7, the plasma arc 8 generates a so-called double arc 9, which flows from the electrode 2 to the tip 5 and the workpiece 7. In the conventional plasma processing torch, the tip 5
Of the torch head 1
Was also causing damage.

Conventionally, these problems have had to rely on the attention of the operator who performs each processing to prevent such a situation from occurring. Therefore, it is difficult for a beginner to leave the work, and he must rely on a highly skilled person.

[Problems to be Solved by the Invention] The present invention has been completed for the purpose of solving such conventional problems and preventing the occurrence of a double arc without relying on the attention of an operator. The plasma processing torch currently on the market has a chip that prevents the occurrence of double arc, which has not been developed, and by extending the life of the chip, the durability of this type of plasma processing torch has been improved. The running cost in chip manufacturing is also reduced, and it depends on how much this kind of plasma processing torch can be supplied at a low cost.

[Means for Solving the Problems] Therefore, as a means for solving the above problems, to extend the life of the tip of the torch for plasma processing of the present invention, a conductive ceramic material is used for the tip for restraining the plasma arc. I decided to adopt it. The torch for plasma processing according to the present invention is characterized in that the tip for restraining the plasma arc is formed of zirconium boride, a composite ceramic material of zirconium boride and boron nitride, or a conductive ceramic material made of chromium carbide, thereby causing the above-described problems. Is to solve.

[Function] In the torch for plasma processing of the present invention, the tip for restraining the plasma arc is made of zirconium boride, a composite ceramic material of zirconium boride and boron nitride, or the conductive ceramic material made of chromium carbide. The passage of the double arc flowing to the workpiece via the electrode tip is substantially cut off, and the occurrence of the double arc is significantly suppressed.

Embodiments of the Invention Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.

FIG. 3 shows an embodiment of the present invention, in which the chip material is replaced with a copper member, and a chip 15 made of conductive ceramic material made of zirconium boride, a composite ceramic material of zirconium boride and boron nitride, or chromium carbide is used. It is what it was. The configuration other than the chip 15 is the same as that of the conventional example, and the description is partially omitted. Further, in the torch head 1 of FIG. 1, the present invention will be described with reference to FIG.

The conductive ceramic material used for the chip 15 of the present invention is dierconium boride, a composite ceramic of dierconium boride and boron nitride, or chromium carbide.
The electrical resistivity of these materials can be arbitrarily selected from about 17 times to 290 times that of the copper member by selecting each material.

These selections may be made as appropriate in consideration of the cost and workability of the material. Accordingly, by using any conductive ceramic chip of these materials for a torch for sound plasma processing, a plasma arc current 8 appropriately supplied between the electrode 2 and the workpiece 7 is obtained.
Will not flow through the chip 15 at all. That is, the path of the double arc 9 described with reference to FIG. 2 is substantially interrupted, and as a result, the occurrence of a so-called double arc is prevented.

On the other hand, during plasma processing, dross scattered from the workpiece and electrode melt adhere to the tip orifice 5a, which was also a major cause of the double arc 9, but the conductive ceramic material was made of copper. As compared with the above member, the adhesion can be remarkably reduced, and the factor of double arc generation is eliminated from this aspect as well.

[Effects of the Invention] As described above, according to the present invention, in the torch for plasma processing, the material of the chip used for the torch is a conductive ceramic material instead of the copper material. The path of the double arc that flows to the workpiece via the relay is almost interrupted. Further, the dross scattered from the workpiece and the electrode melt can be significantly reduced from adhering to the chip orifice. As a result, the occurrence of double arc is remarkably suppressed and eliminated, and an excellent effect can be obtained in preventing chip wear, melting and damage of the torch for plasma processing. This eliminates the necessity of performing the processing operation while paying attention to avoid the occurrence of the double arc, so that anyone can easily perform the operation even if the operator is not highly skilled.

Furthermore, since these conductive ceramic materials can be formed, a large effect can be obtained from the viewpoint of running cost for this kind of chip to be mass-produced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a plasma processing torch of this type to which the present invention can be applied. FIG. 2 is a sectional view of an essential part for explaining a conventional example. FIG. 3 is a sectional view of an essential part for explaining the present invention. DESCRIPTION OF SYMBOLS 1 ... Torch head 2 ... Electrode 5 ... Copper chip (conventional example) 6 ... Shield cup 15 ... Conductive ceramic chip (this invention)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H05H 1/34 B23K 10/00

Claims (1)

(57) [Claims] 1. A plasma processing torch comprising an electrode for supplying a plasma arc current, an electrode holder, a tip for restraining a plasma arc, a gas distributor for supplying a plasma working gas, and a shield cup, wherein the tip is provided with It is made of zirconium boride, a composite ceramic of zirconium boride and boron nitride, or chromium carbide, and is formed of a conductive ceramic material having an electrical resistivity of about 17 to 290 times that of a copper member. Torch for plasma processing.