Non-consumable Electrode For Electric-arc Process

Abstract

A non-consumable electrode for electric-arc processes, in which a metallic clip provided with an electrode insert is positioned in a hollow body so that it is cooled by a cooling medium surrounding the entire surface of the clip and the insert.

Parent Case Text

The present invention is a continuation of application Ser. No. 819,318 filed Apr. 25, 1969, now abandoned.

Description

The present invention relates to apparatus for electric-arc processes, and more particularly it concerns the utilization of non-consumable electrodes for carrying into effect electric-arc processes.

The proposed invention may be used in burners and plasmatrons preferably intended for effecting welding processes, for example, cutting, welding, deposition, coating by dusting, remelting.

It can also be used for effecting thermal treatment, in plasma technique, plasma chemistry, light engineering, spectroscopy, and other electric-arc processes both in an oxidizing and inert media.

Known in the prior art is a non-consumable electrode for effecting electric-arc processes comprising a tip with an insert secured to a hollow body containing a cooling medium (Cf. Author's Certificate No 1070128 granted in the USSR on 18 April 1966).

The electrode insert conventionally utilized heretofore have in the process of continuous arcing burned out at an average rate of 1 mm per hour due for the reason that the cooling medium was remote from the place of the maximum heating of the insert.

Such a rate of erosion of the insert requires frequent replacement of the electrode, and this makes its industrial application inexpedient.

Moreover, high consumption of the insert as made of expensive metal and having a considerable weight at its tip made of highly heat-conducting non-ferrous metal unduly increases the cost of the electrode.

An object of the present invention is to eliminate the above-said disadvantages.

The principal object of the invention is to provide such a non-consumable electrode for effecting electric-arc processes, which would reduce the consumption of expensive metal of the insert and ensure a longer service life thereof.

This object is achieved by providing a non-consumable electrode for carrying into effect electric-arc processes comprising a tip with an electrode insert secured to a hollow body accommodating a cooling medium. According to the invention, the tip includes a metallic clip in which is seated an insert disposed to project inside of the hollow body so that the cooling medium surrounds the entire surface of the casing complete with the insert.

The nature of the present invention will become more fully apparent from a consideration of the following exemplary embodiments thereof, taken in conjunction with the accompanying drawing representing a general view in longitudinal section of a non-consumable electrode intended for carrying into effect electric-arc processes.

A non-consumable electrode for carrying into effect electric-arc processes comprises a tip having enclosed therein an electrode insert 1 and a hollow body 2 accommodating a pipe 3 for supplying a cooling medium into the said body 2. The tip is essentially a metallic clip 4 disposed inside the hollow body 2 in such a manner that the cooling medium surrounds the surface of the metallic clip complete with the insert 1.

Such an arrangement of the casing 4 together with the insert 1 in the body 2 ensures heat removal directly from the zone of maximum heating of the insert 1. The maximum heating zone is disposed on the end of the insert 1, and, as erosion of the latter proceeds, the zone penetrates into the metallic clip 4 surrounded by the cooling medium.

The metallic clip 4 is made of a highly heat-conductive metal, for example copper, offering in this case a minimum resistance to the heat flow from the insert 1 to the cooling medium. This ensures the uniform removal of heat through a thin wall of the clip 4.

In the proposed electrode, water is mainly used as a cooling medium, yet other highly heat-capacity materials, such as carbon dioxide and air, may also be used for this purpose.

Zirconium and tungsten are preferably employed as materials for making the electrode insert therefrom, but there may also be employed other metals for stabilizing the arc burning and improving the electrode operation in a medium corresponding to the metal employed (for example, molybdenum, the medium in which molybdenum burns being an inert gas). In the proposed electrode, tungsten is mainly used as the electrode insert when electric arc is burning in inert gases.

The proposed electrode using a zirconium insert ensures the most stable burning of an electric arc and is capable of operating both in oxidizing (for example, air, oxygen, carbon dioxide, etc) and inert media (for example, argon, nitrogen, etc.), that is, it proves to be universal.

The stable burning of an electric arc is also achieved owing to an improved cooling of the insert, the thermal resistance thereof being increased due to the formation of oxides and zirconium nitrides precluding the melting and evaporating of the insert material during the burning of electric arc.

The hollow body 2 of the non-consumable electrode is employed as a current conductor for the electrode insert 1. This body is made of an electrically conducting material, for example, brass, bronze, aluminum alloys, which material is resistant to the action of the cooling medium to be supplied through the pipe 3 which, in its turn, may be manufactured even of a non-conducting material, for example, plastics.

To raise the heat supply and to achieve the maximum resistance of the electrode, it is advisable to maintain the high heat-capacity cooling liquid, at as low a temperature as possible and to wash the casing and the insert, at a fast speed along the surfaces to be cooled (V =10 m/sec).

Consequently, the non-consumable electrode made as the proposed design, allows the rate of erosion of the insert to be reduced by more as ten times, thus increasing accordingly the potentialities of operation of the electric-arc with the use of this electrode and reducing the consumption of rare and non-ferrous metals used for manufacturing the said electrode.

Moreover, this non-consumable electrode ensures the stable burning of a compressed electric-arc stabilized with air, does not require frequent dismantling and readjustment of the electric-arc unit, and allows the efficient use of industrial apparatus for carrying into effect the highly effectual process of air-plasma cutting.

Although the present invention is described in connection with its preferred embodiment, it is obvious that there may be allowed modifications and variants thereof without departing from the spirit and scope of the invention, which will be readily understood by those skilled in the art.

These modifications and variants are considered to fall within the essence and scope of the invention as defined by the appended claim.

Claims

We claim:

1. A non-consumable electrode for electric-arc processes comprising an electrically conductive hollow body having a free end, an electrically conductive elongate electrode insert, electrically conductive elongate annular means surrounding said electrode insert and interconnecting said electrode insert to said hollow body at said free end thereof, said elongate means being of uniform thickness and having axially opposed open ends one of which exposes said insert internally of said body and the other of which exposes the insert externally of said body, said elongate means and said electrode insert each including a major portion projecting axially into said hollow body, and means defining a passageway into and through said hollow body for the flow of a cooling medium, said elongate means being positioned in said passageway such that said passageway extends along substantially all of said elongate means, whereby the cooling medium is in direct contact with the elongate means and so that said cooling medium can be brought directly into contact with said electrode insert, said insert being adapted for being consumed up to the limits of said elongate means.

2. An electrode as claimed in claim 1 wherein said means for the flow of cooling medium comprises a tube mounted in said hollow body, said tube including an open-ended portion substantially enveloping said electrode insert and elongate means, said open-ended portion being in annular spaced relation with said elongate means and in annular and axial spaced relation with said hollow body to permit the cooling medium to be channelled through said tube along said elongate means and into contact with said hollow body.

3. An electrode as claimed in claim 2, including means for propelling the cooling medium through said tube and throughout said hollow body, said hollow body including means for allowing said cooling medium being propelled therein to exit therefrom.

4. An electrode as claimed in claim 1 wherein said electrode insert is of a material selectively compatible with the environment in which said insert burns.

5. An electrode as claimed in claim 4 wherein said electrode is tungsten when burned in inert gases.

6. An electrode as claimed in claim 4 wherein said electrode insert is zirconium.

7. An electrode as claimed in claim 1 wherein said cooling medium is water.

8. An electrode as claimed in claim 2 wherein said tube is of electrically insulative material.

9. An electrode as claimed in claim 1 wherein said means interconnecting said electrode insert to said hollow body is a metallic clip which is thin-walled and constituted of substantially heat conductive material.