JPS61271800A - Plasma arc torch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] L! Meng (1) 1m! ! F The present invention relates to a plasma arc torch for processing a workpiece using a plasma arc.

Generally, in a plasma arc torch, the workpiece and the 1! Machining is performed using a plasma jet that generates arc discharge between the electrode and the appropriate working gas from a nozzle.

As this type of working gas, inert or reducing gases such as nitrogen, argon, and hydrogen are used, and oxidizing gases such as oxygen and air are used, but they are inexpensive and readily available. In most cases, oxidizing gases are used as working gases because they are easy to use.

By the way, the main part of the tip of a plasma arc torch is often formed in the structure schematically shown in FIG. 1.

Conventionally, in this kind of torch, an electrode 1 and a nozzle 3
For example, the electrode 1 and the nozzle 3 are shielded from oxidizing gas by appropriately coating with a metal oxide material to prevent the electrode 1 and the nozzle 3 from being oxidized. That is, the aim was to reduce wear and tear on the electrode 1 and nozzle 3 due to oxidation.

However, when focusing on arc discharge, 'iIII pole Lt5
In the presence of the gold fill compound coated on the nozzle 3 and the nozzle 3, the discharge point of the arc, that is, the cathode point, is likely to shift.
There was a risk that a double arc would be generated between the electrode 1 and the workpiece 4 via the conductive nozzle 3. Also,
When coating a metal oxide material as described above, it is carried out by thermal spraying or baking, but in this case, the surface of the coated metal oxide material becomes rough, so for example, the surface of the nozzle 3 Spatter and dross were attached. This adhesion of spatter and dross promotes the generation of double arcs, and the deposited spatter and dross fall intermittently, which is unfavorable for processing operations.

To solve the same problem, the present invention has been made by focusing on the above-mentioned conventional problems, and therefore, in a plasma arc torch, the surface of the electrode other than the high melting point insert provided at the tip of the electrode and the conductive The above problem is solved by providing an electroplated layer containing either Ni or Cr on the inner and outer surfaces of the magnetic nozzle.

An electroplated layer containing either Ni or Cr is disposed on the surface of the N pole and the inner and outer surfaces of the conductive nozzle, excluding the high melting point insert, and the electroplated layer containing either Ni or Cr is Since the plating layer prevents the emission of cathode electrons, plasma discharge occurs between the high melting point insert and the workpiece. In other words, the double arc that conventionally occurred is completely eliminated. Of course, since the electroplated layer containing either Ni or Cr has a smooth surface, hardly any spatter or dross adheres to the outer surface of the nozzle. Furthermore, since an electroplating layer containing either Ni or Cr is provided on the surface of the electrode excluding the insert and on the inner and outer surfaces of the conductive nozzle, the electrode and nozzle will remain stable even when oxidizing gas is used. It is not easily oxidized, thus extending the usage time of the electrode and nozzle.

Figure 1 is a diagram schematically showing the main part of the tip of a plasma arc torch. Reference numeral 1 denotes an electrode, which is made of copper or a copper alloy, for example. Reference numeral 2 denotes a high melting point insert provided at the tip of the electrode 1, and is made of, for example, hafnium, zirconium, or an alloy based on these.

Reference numeral 3 denotes a conductive nozzle that electrically insulatingly and coaxially covers the tip of the electrode 1, and is made of, for example, copper or a copper alloy. This nozzle 3 has a small diameter hole 301 that passes through the tip in the axial direction. In the above, an electroplating layer containing either Ni or Cr is provided on the surface of the electrode 1 excluding the insert 2 and on the inner and outer surfaces of the nozzle 3.

In the above configuration, while supplying current between the N pole 1 and the workpiece 4, a working gas such as an oxidizing gas is supplied between at least the electrode 1 and the nozzle 3, and the small diameter hole of the nozzle 3 is The workpiece 4 is processed by a plasma jet ejected from 301.

Although the nozzle 3 is normally used apart from the workpiece 4, the present invention can also be applied to a case where the lower end of the nozzle 3 is brought into contact with the surface of the workpiece 4.

That is, in particular, an electroplated layer containing either Ni or Cr is formed on the outer surface of the nozzle, and the surface of this electroplated layer is smooth, so that the movement of the nozzle that comes into contact with the surface of the workpiece is prevented. This improves the operability of the torch. Furthermore, a space portion of an appropriate shape may be provided inside the electrode 1 and the nozzle 3 to cool each of them, or
A cooling mechanism can be provided outside the nozzle 3. Of course, in the above, an inert or reducing gas can also be used as the working gas. In this case, it is suitable for welding work.

11 animals 11 (A) Electroplated layers containing either Ni or Cr are provided on the surface of the electrode except for the high melting point insert and on the inner and outer surfaces of the conductive nozzle, so (a) plasma discharge is generated reliably only between the high melting point insert provided at the tip of the electrode and the workpiece.

In other words, there is no double arc that occurs in the past, and there is no risk of damaging the various parts of the torch.

(b) Even when an oxidizing gas is used, the electrode and nozzle are not easily oxidized, so that the torch can be used for a long time even with an inexpensive oxidizing gas.

(c) In particular, the outer surface of the nozzle on which the electroplating layer is disposed becomes smooth, and therefore spatter or dross hardly adheres to the outer surface of the nozzle.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing the main part of the tip of a plasma arc torch, which is the object of the present invention. 1... Electrode, 2... High melting point insert, 3... Conductive nozzle

Claims (1)

[Claims] 1. An electrode having a high melting point insert at its tip, a conductive nozzle that electrically insulates and coaxially covers the tip of the electrode, and supplying a working gas between at least the electrode and the nozzle. and a means for supplying current around the electrode and the workpiece, the surface of the electrode excluding the insert and the inner and outer surfaces of the nozzle are coated with either Ni or Cr. A plasma arc torch equipped with an electroplated layer containing