JPS62292276A - Plasma torch - Google Patents

Abstract

PURPOSE:To prevent working accuracy from being lowered by providing magnetic material to a tip part of a plasma torch to weaken the influence of an outside magnetic field and stabilizing a pilot arc. CONSTITUTION:A magnetic shielding member 11 made of the magnetic material with high permeability is fitted detachably and attachably with cap structure, etc., to a jacket 2' of a cathode 1 in the plasma torch. When the pilot arc 10 is generated between the cathode and the jacket 2' in a state with the magnetic shielding member 11 fitted, the magnetic shielding member 11 almost shields the outside static magnetic field. As a result, even if a member and a magnet or a magnetic field with magnetism exist in the neighborhood, the pilot arc 10 is not substantially influenced and does not become unstable by these. Accordingly, the generation of the plasma jet or the plasma arc for working does not become difficult.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a plasma torch used in a plasma processing apparatus that processes a workpiece using energy from a plasma arc or a plasma jet. [Prior art] An example of a conventional plasma torch is explained in Fig. 5. 1 is an anode such as a tungsten rod;
The first mantle 4 is provided on the outer periphery of the first mantle 2 and forms an air flow q) flL approximately 5 therebetween, and the first mantle 4 is provided on the outer periphery of the first mantle 2 and forms an airflow mud path 5t between it. 2, the mantle %6 is a conductive support that supports the cathode 1, 7 is an insulating member for electrically insulating between the conductive support 6 and the first mantle 2, and 8 is the first and second mantle. Mantle 2.4 is an insulating member for electrical insulation.

Note that this is a workpiece processed by a 9#'i plasma jet or plasma arc.

Next, to explain the operation of a plasma torch with such a structure, there is
With the current flowing through the T-channel 5, a voltage is applied between the anode 1 and the first mantle 2 to first generate an arc between the anode 1 and the first mantle 2, and then to generate an arc between the anode 1 and the second mantle 2. A high frequency voltage is applied between the mantles 4 to generate a pilot arc between the cathode 1 and the second mantle 4. In the case of the non-transfer type, the workpiece 91r is processed by generating a grain jet.

In the case of the transfer type, a voltage t- is applied between the terminal electrode 1 and the workpiece 9, a plasma arc is formed between the anode 1 and the workpiece 9, and the workpiece 9t- is processed. However, if the workpiece 9 is made of a magnetic material, or if there is a magnetic member near the plasma torch, or if the plasma torch is in a relatively strong external magnetic field. It has been found that in some cases, the arc becomes unstable due to the influence of magnetism. In particular, in the case of a pilot arc, since the current is small, it is easily influenced by external magnetism, and it may not be possible to generate a plasma jet or plasma arc. Furthermore, in the case of a plasma jet or plasma arc with a relatively small current, it is relatively susceptible to the influence of external magnetism, which causes the plasma jet or plasma arc to become unstable and fluctuate, resulting in a reduction in machining accuracy. Ta.

[Friendly means of solving problems]

A magnetic material is provided at least at the tip of the plasma torch to weaken the influence of an external magnetic field. [Function] The magnetic material provided at least at the tip of the plasma torch can significantly reduce the shadow of the external magnetic field. Therefore, even if there is a magnetic member in the vicinity of the plasma torch, the pilot arc will be as stable as when it is not affected by the magnetic influence t#, and the generation of the plasma jet or plasma arc for machining will have no effect. ? ] - Not given. The same applies to small current plasma jets and plasma arcs.
Since L is stable, there is no decrease in machining accuracy.

〔Example〕

An embodiment of the present invention will be fully explained with reference to FIG. 1. Members having the same symbols as those shown in FIG. 5 indicate the same parts.

In the figure, reference numeral 11 indicates the entire magnetic shielding member made of a magnetic material with high magnetic permeability, which is an important component of the present invention, and in this embodiment has a cap structure that can be attached to and detached from the mantle 2'. Here, the magnetic shielding member 11 is made of a magnetic material made by appropriately treating pure iron, a base metal mainly composed of iron, nickel, cobalt, etc., or a compound thereof. A pilot arc 1 is inserted between the cathode 1 and the mantle 2' with the cap-shaped magnetic shielding member 11 attached to the mantle 2'.
0, the magnetic shielding member 11 mostly shields the external quiet magnetic field, so even if there is a magnetic member, magnet, or magnetic field nearby, the pilot arc 10
is virtually unaffected and 11 hardly destabilized. Therefore, it is not difficult to generate a plasma jet or a plasma arc for processing. Further, even when a plurality of plasma torches are arranged and operated in the vicinity, the plasma torch is not affected by magnetic fields caused by other plasma jets or plasma arcs. Here, the small diameter of the tip of the magnetic shielding member 11 is equal to or larger than the nozzle diameter of the mantle 2',
It is desirable that the size be as small as possible without being damaged by the direct heat of the plasma jet or plasma arc.

Next, FIG. 2 shows another embodiment of the plasma torch according to the present invention, in which the cap-shaped magnetic shielding member 11 is completely attached to the second jacket 4, and other details are the same as those in FIG. 1. Since they are similar, the complete explanation will be omitted. In this figure, the same symbols as those shown in FIG. 5 indicate the same members.

FIG. 16 shows another embodiment of the present invention in which a fifth mantle disposed outside the second mantle 4 is composed of a magnetic shielding member 11. The magnetic shielding member 11 that constitutes the entire third mantle is an electrically insulating material 12? A gas flow path 16 is formed between the second mantle 4 and the magnetic shielding member 11 which is the mantle of O6.

The diameter of the tip of the magnetic shielding member 11 serving as the third mantle is:
It is larger than the nozzle diameter of the second mantle 4.

According to this embodiment, the magnetic shielding member 11 is also used as the third mantle, and is therefore economical.

Furthermore, another embodiment of the present invention is shown in which the Oh magnetic shield member 11 also serves as a part of the water cooling pipe. Plasma torches, especially their tips, are exposed to high temperatures and are therefore water-cooled, and many plasma torches are equipped with water coolers at their tips. The outer wall of the second mantle 4 constitutes the entire inner wall of the water-cooled pipe, and the part 4' integrally formed with the second mantle 4 and the magnetic shielding member 11 fixed to this part 4' form the entire inner wall of the water-cooled pipe. It consists of the entire outer wall. In other words, in this embodiment, since the magnetic shield member 11 constitutes a part of the water cooling mechanism, there is no need to provide a separate member exclusively for the magnetic shield, which is economically advantageous, and the plasma torch does not become large. Note that water flows as shown by the arrow, and if the magnetic shielding member 11 is rusted by this water, a rust-resistant metal film such as nickel plating or a highly heat-resistant organic film should be formed on the magnetic shielding member 11. Good.

〔Effect of the invention〕

As mentioned above, according to the present invention, at least the tip of the plasma torch is provided with a magnetic shield member made of a magnetic material with high magnetic permeability, so that the following effects 1-N are achieved.

(1) Since there is a magnetic fCs material near the plasma torch, the pilot arc will not become unstable even if the plasma torch is located within a specific external static magnetic field. Therefore, the processing plasma will not flow from the pilot arc. When a jet or plasma arc is generated, there is no failure or special operation. 0. When machining is performed using a pilot arc, stable machining can be performed and good machining results can be obtained.

(6) Mutual interference can be prevented even when a plurality of plasma torches are arranged relatively close to each other and operated, allowing stable processing operations to be performed.

(4) Even in the case of a relatively small current gamma arc or plasma jet, it is difficult to accept external magnetic effects and there is no reduction in machining accuracy.

[Brief explanation of the drawing]

1 to 4 are diagrams showing different embodiments of the plasma torch according to the present invention, and FIG. 5 is a diagram showing a conventional plasma torch. 1.Second mantle 6.5...First and second channels 11...Magnetic shielding member Patent applicant Origin Electric Co., Ltd. Engraving of the drawing (no changes to the content) 1st Figure 2 Amendment of cause procedure dated September 7, 1986 Mr. Commissioner of the Japan Patent Office, μ is indicated in the case, Patent Application No. 135560, 1986, No. 2
Title of the invention: Plasma torch 3, relationship to the amended case: Patent applicant

Claims (1)

[Claims] In a plasma torch comprising a cathode and one or more mantles disposed around the cathode, at least a tip portion of the plasma torch is provided with a magnetic material with high magnetic permeability for weakening the influence of an external magnetic field. A distinctive plasma torch.