JP2625234B2 - Plasma electrode material - Google Patents

Description

The present invention relates to an electrode material for a plasma cutting torch.

(Prior Art) FIGS. 6 and 7 are conceptual diagrams of a conventional plasma cutting torch. FIG. 6 shows a state when a pilot arc is generated, and FIG. 7 shows a state when a plasma arc is generated.

In the figure, reference numeral 1 denotes a nozzle narrowed down in a funnel shape at the tip. An electrode support tube 6 is provided in the nozzle 1 via a working gas swirling / inner tube fixed ring 12 made of an insulator, and a water-cooled outer tube is provided on the outer peripheral surface of the nozzle 1 in a watertight structure with the nozzle 1. 2
Are connected. Cooling water supply pipe 3
And a cooling water discharge pipe 4. The electrode support tube 6 is attached to the tip of a current-carrying pipe 8, and the tip of an electrode cooling water conduit 9 is inserted into the electrode support tube 6. Tungsten, hafnium, zirconium A rod electrode 7 made of a material such as the above is provided. A connecting pipe 13 made of an electrical insulator is provided between the nozzle 1 and the power supply pipe 8, and the nozzle 1 between the connecting pipe 13 and the working gas swivel / inner cylinder fixed ring 12 is operated. The gas supply pipe 5 is connected. An electrode cooling water supply pipe 10 and an electrode cooling water discharge pipe 11 are connected to the electrode cooling water conduit 9. The nozzle 1 is connected to a pilot arc power supply 16 via an electric wire 18b ', the energizing pipe 8 is connected to a plasma electric wire 17 via an electric wire 18a, and connected to the pilot arc power supply 16 via electric wires 18a and 18a'. . The plasma power supply 17 is connected to the workpiece 15 via an electric wire 18b. In this way, a plasma arc 14, a pilot plasma 14a (see FIG. 7) and a plasma arc (or arc) 14b are generated between the electrode support cylinder 6 and the workpiece 15. 6 and 7, the hatched arrow (-→) indicates the flow direction of the cooling water, and the arrow (→)
Indicates the flow direction of the working gas.

Before generating a plasma arc, cooling water is first introduced into the plasma torch from the nozzle cooling water supply pipe 3 and the electrode cooling water supply pipe 10, and cooling of the nozzle 1, the electrode support tube (tip) 6 and the rod electrode 7 is started. . Next, a working gas such as argon, hydrogen, oxygen, air, and a mixed gas thereof is introduced into the torch from the working gas supply pipe 5 and discharged from the tip of the nozzle 1. At this time, the working gas is swirled by the working gas swirling and inner cylinder fixed ring 12, and is supplied to the nozzle tip. Next, pilot arc power supply 16
Is operated, and as shown in FIG.
A pilot arc 14a having a small current is generated between the two.
The working gas supplied to the tip of the nozzle 1 by the heat generated by the pilot arc 14a becomes a swirling plasma flow, and extends downward from the nozzle 1 port as the pilot plasma 14b. After the pilot plasma 14b is connected to the material 15 to be cut, the pilot arc power supply 16 is turned off, and simultaneously the plasma power supply 17 is operated, so that the arc 14a is
High current (100-250A) by transferring between material and workpiece 15
Flow. As a result, a plasma arc 14 is generated, and the workpiece 15 is cut.

(Problem to be Solved by the Invention) The material of the rod electrode 7 of the conventional plasma cutting torch is made of a pure metal of hafnium (Hf) or zirconium (Zr), or an alloy of both metals, and generates a plasma arc. The rear part of the side is directly cooled with water to suppress the temperature rise of the electrode material, and measures are taken to prolong the electrode life. However, when the plasma arc current increases and oxygen is used as the working gas, the oxidation reaction becomes vigorous, and the life of the electrode is significantly shortened. For this reason, in the cutting operation of the actual machine, the electrode replacement frequency is high, the work efficiency is low, and the cost of the electrode as a consumable is extremely high.

The present invention has been made in view of the above point, and an object of the present invention is to provide a plasma cutting electrode material that can prolong the life of an electrode material and significantly reduce the cost of consumables due to a cutting operation.

(Means for Solving the Problems) The present invention provides: (1) an electrode for a plasma cutting torch, comprising: at least one compound selected from the group consisting of hafnium carbide, zirconium carbide, hafnium nitride and zirconium nitride. And (2) the compound according to claim (1), comprising: an oxide of one or more elements selected from the group consisting of Y, Sr, B and a rare earth element, and an oxide of Y, Sr, B and a rare earth element. One or more oxides of the group, one of the group consisting of Y, Sr and borate of the rare earth element
An electrode material for a plasma cutting torch, characterized by containing one or more of at least one kind of borate.

(Action) The properties required for the electrode material for air plasma cutting and oxygen plasma cutting are high melting point, high melting point of oxide, good electrical conductivity, high thermal conductivity, and work for arc generation. The function must be small. on the other hand,
The electrode materials for air plasma cutting and enzyme plasma cutting are
It is immediately oxidized in a high temperature plasma environment, and the arc (ie, electrons) is expected to have originated from the oxide surface.
Therefore, the electrode material does not need to be a metal, and it is sufficient that the oxide has a high melting point, good electrical conductivity, high thermal conductivity, and a low work function.

In consideration of the above, in the present invention, the basic component is Hf or
Zr carbide or nitride, or a mixture thereof. These materials change to HfO ₂ or ZrO ₂ in a high-temperature oxidizing atmosphere of air and oxygen plasma, but these oxides have high melting points and are stable.

Further, in order to lower the work function, one or more elements selected from the group consisting of Y, Sr, B and rare earth elements, or oxides or borates thereof, and A small amount of a mixture of elements, oxides and borates was added to form an electrode material.

The electrode material of the present invention employs the above basic components, so that the melting point of the material is about 3800 compared to metal Zr or Hf.
° C and can be stable at high temperatures. Further, in a high-temperature oxidizing atmosphere of air plasma and oxygen plasma, the above basic components generate ZrO ₂ and HfO ₂ , and since their melting points are high and stable, metal Zr and Hf 2
The life of the electrode can be extended as compared with the case of (1).

Further, the above-mentioned trace added components are aggregated in the arc generating portion of the material of the basic component of the present invention, lowering the work function of the electrode material, and lowering the temperature at the arc generating point. Therefore, the life of the electrode material can be further extended.

(Example) A rod electrode having a diameter of 1.5 mm was formed using the substances shown in FIGS. 1 to 5 as the electrode material of FIGS. 6 and 7, and a plasma was formed under an oxygen atmosphere as a working gas. At a voltage of 150 V, the life of the electrode was examined.

1 and 2 show conventional electrode materials, Hf and Zr.
2 shows the electrode life of an electrode material of HfC, ZrC, HfN, ZrN or a mixture thereof according to the present invention.

FIG. 3 is an electrode material obtained by adding at least one element of Y, Sr, B, and rare earth elements to HfC, ZrC, HfN, ZrN or a mixture thereof according to the present invention, or further adding an oxide of the element. FIG. 4 shows the electrode life of the present invention.

FIG. 4 shows that HfC, ZrC, HfN, ZrN or a mixture thereof according to the present invention is mixed with one or more oxides of Y, Sr, B and rare earth elements, or borate of Y, Sr and rare earth elements. 3 shows the electrode life of an electrode material to which is added.

FIG. 5 shows an electrode material obtained by adding one or more borates of Y, Sr, and rare earth elements to HfC, ZrC, HfN, ZrN or a mixture thereof according to the present invention, or Y, Sr, and rare earth elements. FIG. 4 shows the electrode life of the present invention.

As is clear from FIGS. 1 to 5, it can be seen that the life of the electrode material of the present invention is greatly extended as compared with the conventional Hf and Zr electrode materials.

(Effect of the Invention) In the present invention, by adopting the above configuration, the life of the plasma cutting electrode is extended, the cutting efficiency is improved, the cost of the electrode consumables is reduced, and high-efficiency cutting is enabled.

[Brief description of the drawings]

1 to 5 are diagrams showing the life of the electrode material of the embodiment,
FIG. 6 is a conceptual diagram showing a structure of a plasma cutting torch when a pilot arc is generated, and FIG. 7 is a conceptual diagram showing a structure of a plasma cutting torch when a plasma arc is generated.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takashi Hirayama 2--20-31 Shimizu, Minami-ku, Fukuoka City, Fukuoka Prefecture Inside Nippon Tungsten Co., Ltd. (72) Inventor Shigeya Sakaguchi 2--20, Shimizu, Minami-ku, Fukuoka City, Fukuoka Prefecture No. 31 Japan Tungsten Co., Ltd. (72) Inventor Akira Mishima 2-20-31 Shimizu, Minami-ku, Fukuoka City, Fukuoka Prefecture Japan Tungsten Co., Ltd. (56) References Patent 2521307 (JP, B2)

Claims (2)

(57) [Claims] 1. An electrode material for a plasma cutting torch, comprising at least one compound selected from the group consisting of hafnium carbide, zirconium carbide, hafnium nitride and zirconium nitride. 2. The compound according to claim 1, wherein said compound comprises one or more elements selected from the group consisting of Y, Sr, B and a rare earth element, and an oxide of Y, Sr, B and a rare earth element. One or more of the oxides, one of the group consisting of Y, Sr, and a borate of a rare earth element
An electrode material for a plasma cutting torch, wherein one or more of borate salts are contained in combination.