JPH06302398A - Electrode structure for plasma torch - Google Patents

Abstract

PURPOSE:To improve heat efficiency for a heating object by preventing a temperature drop in a plasma torch while preventing the consumption of a cathode electrode due to high temperature. CONSTITUTION:A plasma torch cathode 3 is made flat type to cover the base end of a chamber 1 made of metal having a low melting point such as copper, copper alloy or the like. According to this construction, the contact area of high temperature plasma gas in the chamber 1 and the plasma torch cathode 3 decreases, and even when the cathode 3 is cooled, the substantial temperature drop of the plasma gas in the chamber 1 can be restrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode structure of a plasma torch used for smelting / extraction, melting / refining, thermal spraying, surface modification and the like in a metal process.

[0002]

2. Description of the Related Art Application of plasma to a metal process has been tried as a large-scale alloy steel melting furnace, reducing gas heating, etc. as an application research on high-temperature metallurgical reaction, and some are commercially operated as actual operation equipment. Many.

A plasma torch used for plasma generation forms a high temperature plasma by an arc generated between a cathode and an anode, and in particular, problems such as wear of electrodes and refractories must be solved. It is left.

FIG. 3 is a sectional view showing a so-called non-transfer type plasma torch conventionally used for welding, melting, refining, etc., in which the current path is completed inside the torch.

This plasma torch is provided with a cylindrical arnode 20 and a cathode 21 each having a water jacket on the same axis, and a gas injector 22 and a cathode 2 between the arnode 20 and the cathode 21.
The magnetic coil 23 is provided so as to surround the outer periphery of the magnetic field coil 1. Reference numeral 24 is a DC power supply for applying electric power.

In the device, an arc A is generated by causing a discharge between the arnode 20 and the cathode 21,
In order to prevent local wear of the electrodes at that time, a DC magnetic field is applied to the generated arc by the magnetic coil 23 to give a Lorentz force, or a swirling flow of gas supplied from the gas injector into the torch is used. Measures such as forcibly moving the arc spot and soaking the temperature of the entire electrode are taken.

[0007] Further, for example, JP-A-63-252398.
The publication describes a method of adjusting the wear of the arc, in which the arc is controlled so that the arc is blown away in the longitudinal direction by a method of reciprocating along the inner surface of the upstream electrode so that the arc root is moved.

Further, the arc plasma has a high temperature of several thousand degrees or more, and it is necessary to pass cooling water through a water jacket to protect the anodes and the cathode electrode from this high temperature. However, in order to efficiently obtain a high-temperature plasma jet, it is necessary to discharge the plasma gas whose temperature has once risen without causing the temperature to drop. From this point, cooling the cathode is a negative factor. Becomes

In the above-described conventional plasma torch, the car sword has a cylindrical shape, and a water jacket is formed on the outer periphery of the car sword, and cooling water is supplied thereto to prevent the cathode electrode from being worn due to high heat. Therefore, the contact area between the high temperature plasma gas and the cathode is large, and by cooling the cathode by passing water through the water jacket, the temperature of the plasma gas is significantly lowered, and the thermal efficiency of the heating target is lowered. is there.

[0010]

The problem to be solved by the present invention is to prevent the wear of the cathode electrode due to a high temperature and prevent the temperature inside the torch from decreasing, thereby improving the thermal efficiency of the object to be heated. is there.

[0011]

The electrode structure of the plasma torch of the present invention is a plasma torch in which an arc is generated between a cathode and an anode to generate thermal plasma. It is characterized by having a flat plate shape. Here, a low melting point metal such as copper or copper alloy can be used as the material of the cathode.

[0012]

[Function] By changing the shape of the cathode from the conventional cylindrical shape to the flat shape, the contact area between the high temperature plasma gas in the chamber and the cathode is reduced, and even when the cathode is cooled, the plasma gas in the chamber is greatly reduced. It is possible to suppress the temperature drop.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the present invention will be specifically described below with reference to the embodiments shown in the drawings.

FIG. 1 shows a first embodiment of the present invention, which is a non-transfer type plasma torch.

In the figure, 1 is a cylindrical chamber provided with a cooling water jacket, and 2 is a gas injector for supplying plasma generating gas. At the base end of the cylindrical chamber 1, there is provided a flat-shaped chassis 3 having a water jacket on the outside. 4 is the generated arc A
Is a magnetic coil for forcibly moving the arc spot of No. 3 to prevent uneven wear of the cathode 3. In this embodiment, the negative side of the DC power supply 5 is connected to the cathode 3 and the positive side is connected to the cylindrical chamber 1, which serves as the anode.

In the same apparatus, a plasma-generating gas is spirally supplied from a gas injector 2 into the cylindrical chamber 1, and in this state, the cathode 3 and the cylindrical chamber 1 are supplied.
The arc A is generated by the discharge with the (anode), and the plasma generation gas is discharged to the outside as a high temperature plasma jet. A magnetic field is applied to the generated arc A by the magnetic coil 4, and the Lorentz force causes the arc spot to move.

Cooling water is supplied to the water jackets of the cylindrical chamber 1 and the cathode 3, respectively, to prevent damage to the chamber 1 and the cathode 3 due to high heat.
At that time, since the cathode 3 has a flat plate shape, the area in contact with the high-temperature gas in the chamber 1 is smaller than that of the conventional cylindrical one, and the temperature of the plasma gas whose temperature has risen is not significantly lowered. Only cooling is possible. Further, since the cathode 3 is formed in a flat plate shape, the length of the entire plasma torch is shortened and the size can be reduced. Furthermore, since the cathode 3 can be made thick, a plasma torch with a long product life can be obtained.

FIG. 2 shows a plasma torch according to a second embodiment of the present invention, which is an example of application to a so-called transition type. In this embodiment, the same reference numerals are given to those corresponding to the previous embodiments.

In the transfer type plasma torch of the present embodiment, the chamber 8 (anode) is used only for ignition, the positive side of the electrode is connected to the heating object 7, and the heating object 7 serves as an anod. . In addition, the cylindrical chamber 8 of this embodiment has a entangled portion 8a formed in the middle thereof, whereby the plasma can be narrowed down and a longer and stable plasma can be obtained.

Also in the transfer type plasma torch of this embodiment, since the cathode 3 has a flat plate shape, the area in contact with the high temperature gas in the chamber 1 is smaller than that of the conventional cylindrical one, so that the gas content is significantly increased. It is possible to achieve the same effects as in the previous embodiment, such as the cooling of only the cathode 3 without causing a temperature drop.

[0021]

According to the present invention, the following effects can be obtained.

(1) By changing the cathode from a conventional cylindrical shape to a flat shape, the contact area between the high temperature gas in the chamber and the cathode is reduced, and the temperature of the high temperature plasma gas is not lowered. , The cathode can be cooled.

(2) For the same reason, the plasma torch can be made thick without changing the overall size of the plasma torch, and the plasma torch can have a long product life.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a non-transferred plasma torch that is a first embodiment of the present invention.

FIG. 2 is a sectional view of a transfer type plasma torch according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional non-transfer type plasma torch.

[Explanation of symbols]

 1 chamber (anode) 2 gas injector 3 cathode 4 magnetic coil 5 DC power supply 7 object to be heated (anode) 8 chamber

Claims (1)

[Claims] 1. A plasma torch for generating a thermal plasma by generating an arc between a cathode and an anode, wherein the cathode has a flat plate shape covering a base end portion of a chamber. Construction.