JPH05237665A - Plasma cutting torch - Google Patents

Abstract

PURPOSE:To prolong a service life of negative electrode material, to prevent burning and to improve safety by preventing the negative electrode material from dropping out in the plasma cutting torch using orifice gas. CONSTITUTION:The intermediate diameter of the negative electrode material 11 arranged on the tip central part of an electrode 2 is set smaller than the tip diameter and the rear end diameter and the peripheral whole surface thereof is wrapped with the electrode 2, by which the negative electrode material 11 can be prevented from dropping out due to looseness caused by the difference in the coefficient of thermal expansion between the negative electrode material 11 and the electrode 2 when heat of a plasma arc is received.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a long-life and highly safe plasma cutting torch using a working gas.

[0002]

2. Description of the Related Art A conventional plasma cutting torch will be described below.

As shown in FIG. 3, from a cutting power source 17 for supplying power to the plasma cutting torch, a drain hose 21 which has a built-in electric wire and drains cooling water, and cooling water is supplied to the plasma cutting torch 14. A water supply hose 22 for sending, a gas hose 25 for sending a working gas, and a pilot cable 24 for carrying a high frequency for making an arc start good.
Then, the switch cables 23 are bundled and extended, and the plasma cutting torch 14 is attached to the tip thereof. Further, the grounding cable 18 connects the cutting power source 17 and the processing base material 19. In the figure, 15 is a compressor for compressing the working gas and sending it to the plasma cutting torch 14, 16 is a regulator for adjusting the secondary pressure of the working gas to a constant value, 20
Is a water supply pump.

As shown in FIG. 4, a plasma cutting torch 1
A hollow electrode 2 is screwed and attached to the tip of a tubular body fitting 1, and an O-ring 3 for preventing leakage from the screwed portion is interposed at the tip of 4. The introduction pipe 4 inserted in the main body metal fitting 1 and the shaft core of the electrode 2 guides the working gas or the cooling water to the electrode 2.

A cylindrical cathode material 5 made of zirconium or hafnium is embedded in the tip of the electrode 2.

The tip 6 is attached to the tip of an orifice 7 made of an insulating material, which is fitted over the metal fitting 1 and the rear part of the electrode 2 and surrounds the tip of the electrode 2 with a gap. 2 and the chip 6 are electrically insulated. The tip 6 is made of copper or copper alloy and limits the plasma arc supplied to the base material 19. A small-diameter hole 8 is formed at the tip of the orifice 7 and opens toward the space between the orifice 7 and the electrode 2.

The outside of the orifice 7 is a working gas supply path 1
It is enclosed by an insulating nozzle 9 that forms 0 and prevents the conductive portion from being exposed to the outside. The tip of this nozzle 9 is joined to the tip 6. The dotted white arrow A in the figure indicates the flow direction of the working gas supplied to the supply passage 10, and the white arrow B indicates the working gas supplied to 2 through the introduction pipe 4 and discharged through the outside of the introduction pipe 4. The direction of cooling water flow is shown.

The entire surface of the cathode material 5 excluding the tip surface thereof penetrates the tip portion of the electrode 2 made of copper or copper alloy and faces the inside of the hollow portion. The outer diameter dimension Rb of the tip portion, the outer diameter dimension Ra of the middle portion and the outer diameter dimension Rc of the rear end portion of the cathode material 5 are the same.

The electrode 2 made of copper or copper alloy surrounding the whole cathode material 5 is cooled with a working gas or cooling water, or a part of the cathode material 5 is directly cooled, so that the plasma arc is tightened. I was cutting.

[0010]

However, in the above-mentioned conventional configuration, loosening occurs due to the difference in expansion coefficient between the cathode material 5 and the electrode 2 due to the effect of heat generated by the plasma take.
There is a problem that the thermal conductivity is deteriorated and the cooling effect is reduced, and in some cases, the cathode material 5 falls out, which causes the chip 6 and the plasma cutting torch to be burnt, and thus causes an electric shock. Was there.

The present invention solves the above-mentioned problems of the prior art. It is possible to maintain the cooling effect of the cathode material and prevent the cathode material from slipping out, thereby improving the life of the cathode material and preventing the tip and the plasma cutting torch from burning. And a plasma cutting torch having improved safety.

[0012]

In order to achieve this object, a plasma cutting torch according to the present invention has a cathode material arranged at the center of the tip of an electrode whose intermediate diameter is smaller than the tip diameter and the rear diameter. The outer circumference of the outer circumference is set and the outer circumference of the outer circumference of the cathode material is set to be the same and the rear end diameter is set larger than those. It is configured to include a metal piece that is externally encapsulated by an electrode and is pressed into or screwed into contact with the rear end portion.

[0013]

In this structure, the cathode material is prevented from coming off due to the looseness caused by the difference in expansion coefficient between the cathode material made of zirconium or hafnium and the electrode made of copper or copper alloy, which is generated by the heat of the plasma arc. ..

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 showing an embodiment of the present invention
Then, the same parts as those in the conventional example are designated by the same reference numerals, and the description thereof will be omitted. Since the overall structure of the plasma cutting torch is the same as that of the conventional example described in FIG. 3, the description thereof will be omitted.

(Embodiment 1) A first embodiment of the present invention will be described below.

As shown in FIG. 1, the feature of the present embodiment is that the conventional cathode material 5 is replaced with the intermediate diameter Ra of the tip diameter Rb and the rear diameter of the conventional cathode material 5. The point is that the cathode material 11 is made smaller than the diameter dimension Rc.

With this structure, when receiving the heat of the plasma arc, the cathode material 11 made of zirconium or hafnium is produced.
It is possible to prevent the cathode material 11 from coming off due to loosening caused by the difference in expansion coefficient between the electrode 2 and the electrode 2 made of copper or copper alloy, and perform plasma cutting with stable cutting quality for a long time. In addition, the work can be automated and the safety can be improved.

(Embodiment 2) A second embodiment of the present invention will be described below. As shown in FIG. 2, the difference from the configuration of the first embodiment is that the cathode material 11 has the tip diameter Rb and the intermediate diameter Ra the same, and the rear diameter Rc is Ra and Rb. The metal piece 13 is press-fitted or screwed into contact with the rear end portion of the cathode material 12 which is larger than the above.

The effect produced by this structure is similar to that of the first embodiment.

[0020]

As is apparent from the above description of the embodiments, in the present invention, the cathode material disposed at the center of the tip of the electrode has the intermediate diameter set smaller than the tip diameter and the rear diameter, and ,
A structure in which the entire outer circumference is encapsulated by electrodes, or the cathode material has the intermediate diameter and the tip diameter set to the same size, the rear end diameter is set larger than those, and the entire outer circumference is encapsulated by the electrodes. With the configuration in which the metal piece is pressed into or screwed into contact with the rear end part, the cooling effect of the cathode material is maintained and falling off is prevented, the life of the cathode material is improved, and the tip and the plasma cutting torch are prevented from burning. It is possible to realize an excellent plasma cutting torch with improved safety.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing the concept of a plasma cutting torch according to a first embodiment of the present invention.

FIG. 2 is a sectional view of an essential part showing the concept of a plasma cutting torch according to a second embodiment of the present invention.

FIG. 3 is a schematic perspective view showing a cutting state of a base material of a conventional plasma cutting torch.

FIG. 4 is a sectional view of an essential part showing the concept of a conventional plasma cutting torch.

[Explanation of symbols]

 2 electrode 4 introduction tube 11 cathode material

Claims (2)

[Claims] 1. A hollow electrode made of copper or a copper alloy disposed at the tip of a cylindrical body fitting, an introducing pipe for introducing working gas or cooling water into the body fitting and the electrode, and the electrode. A tip attached to the tip of an insulator-made orifice arranged so as to surround the tip of the electrode with a gap, and a cathode material that forms an electron emission surface attached to the center of the tip of the electrode. The material is a plasma cutting torch in which the intermediate diameter is set to be smaller than the front end diameter and the rear end diameter, and the entire outer peripheral surface is enclosed by the electrodes. 2. The cathode material is such that the intermediate diameter and the tip diameter are the same, the rear end diameter is set to be larger than those, and the entire outer peripheral surface is enclosed by the electrode, and the rear end portion of the cathode material is provided. The plasma cutting torch according to claim 1, comprising a metal piece which is pressed into contact with and screwed into.