US3463957A - Arc plasma torch with same liquid cooling means for electrodes - Google Patents

Description

ARC PLASMA TORCH WITH SAME LIQUID COOLING MEANS FOR ELECTRODES Filed April e, 1966 Aug; 26, 1969 e. FuKslEwlcz 2 Sheets-Sheet 1 Edmund Fuksewicz INVENTQR ARC PLASMA TORCH WITH SAME LIQUID COOLING MEANS FOR ELECTRODES Filed April 6, 1966 Aug. 26, 1969 E. FuKsn-:wlcz

2 Sheets-Sheet 2 Eclruncl Fuksiewicz INVENTOR.

BY g bw fw Attorney Fig.

United States Patent O U.S. Cl. 313-32 5 Claims ABSTRACT F THE DISCLOSURE Plasma torch with an electrode assembly in a generally cylindrical housing having channels for the circulation of a cooling fluid and for the admission of a gas, the assembly including a hollow stem seated in the housing through the intermediary of a resinous layer, a generally cupshaped cathode structure engaging the open end of the stem, a nozzle-shaped anode confronting that structure and a guide ring for the gas flow contacting the anode but separated from the cathode through an interposed insulating spacer; water admitted through the stem ilows through a feeding tube into the cathode structure, then passes through a duct within the layer into a channel of the housing which opens toward the anode, and leaves via another housing channel.

My present invention relates to a direct-current-arc plasma torch, a so-called plasmatron, destined especially for cutting various materials, particularly metals, by means of a plasma jet from any gas.

As known, hitherto used plasma torches essentially consist of two electrodes, i.e. a cathode and an anode which are fixed in a special body constituting the housing of the torch. The torches operate in such a manner that into the electric arc, produced between the said electrodes, gas is introduced under pressure which under the action of the high temperature of the arc is converted into a plasma jet constituting the cutting agent.

In conventional constructions of such torches, the cathode is xed in a special housing which in turn is fastened to an elongate stem. The anode is constituted by a metal nozzle.

On account of the high temperature of the plasma, the component parts of the torch, especially the cathode together with its holder and the anode, require intensive cooling. As there exists simultaneously the necessity of electrically insulating the two electrodes from one another, the cooling has heretofore been effected by the circulation of a cooling medium by way of outer liquid conduits made of insulating material.

Such a cooling system exhibits, however, the disadvantage that it requires special connector pipes for feeding and carrying off the cooling medium which complicates the construction of the torch and its operation.

On the other hand, owing to the presence of several replaceable elements in the body constituting the outer housing, prior torch constructions gave rise to some difliculties in obtaining the required elect-ric insulation and the proper iluidtightness in the circulation system for the cooling medium.

The object of my present invention is to provide a torch of this type which is free from the above-mentioned inconveniences and which affords the required insulation of its electrodes and iluidtightness of its cooling system. This object is realized by the torch according to the invention. It comprises, like known torches, a body in which all the component parts are fixed, more specifically a tubular stem, having a cathode indirectly seice cured thereto through a holder, and a confronting anode in the form of a nozzle.

For the purpose of illustrating a preferred embodiment, a torch according to the invention is schematically shown in the accompanying drawing in which:

FIG. 1 is a longitudinal section of the torch, the cooling system being exposed;

FIG. 2 is another longitudinal, section showing the way of the gas flow; and

FIGS. 3 and 4 are enlarged sectional views showing alternate joints between the cathode holder and the tubular stem.

The torch according to the invention has a tubular stern 1 fastened in a generally cylindrical housing 5 by a tight joint including a layer 15 of cast synthetic resin, a replaceable holder 3 for a cathode 14 being axially pressed onto the core 1 by an insulating spacer 11 overlying a ring 9 and a replaceable nozzle 6 which constitutes the anode.

As illustrated in FIG. 3, the cathode 14 may be supported on an electrode body 3 forming a frustoconical seat for the beveled end of a stem 1'. In the assembly shown in FIGS. 1, 2 and 4, however, the holder 3 is received in a cylindrical bottom recess of stem 1 with interposition of an O-ring 17 between the holder and the peripheral well of this recess.

The construction of the torch according to the invention, the circulation of the cooling medium and the way of the gas flow are described below in a more detailed manner by way of example.

The cooling water is supplied to the torch through the stem 1 and flows then through a feed pipe 2 into the generally cup-shaped body 3 serving as a holder for the cathode. The body 3 or 3 is sealed to the stern 1 or 1 by the conical joint of FIG. 3 or by the use of a selftightening rubber O-ring as shown in FIGS. l, 2 and 4. From the body 3 supporting the cathode 14, the water flows through the space existing between the pipe 2 and the stem 1 to and through a discharge pipe 4, thereafter through a longitudinal channel 18 in the housing 5, closed by a plug 27, into an outer peripheral groove 25 of nozzle 6 and, after washing around said nozzle, through another longitudinal channel 19 and through a nipple 7 outwardly. The nozzle 6 constituting the anode of the torch is sealed by means of two self-tightening rubber O- rings 20, 21 contacting the inner wall surface of housing 5 above and below the ring space 25. The assembly is completed by a retaining cap 16 engaging a threaded flange 26 of the housing, thus holding the anode structure 6, 9, the spacer 11 and the cathode structure 3, 14 in position.

The stem 1 is electrically insulated from the housing 5 by the intervening layer of cast synthetic resin 15. The pipe 4 is made of insulating material.

The gas is supplied to the torch through a nipple 10, FIG. 2, mounted like the nipple 7 on the periphery of housing 5, and through another axially extending channel 22 in the housing, whereupon the gas is conveyed to a gas chamber 23 in the ring 9 shaping the flow, this ring having entrance ports 24 which open tangentially onto its inner surface to cause a whirling of said gas which is then introduced into the space existing between the cathode holder 3 and the nozzle 6.

The gas may also be introduced axially if the entrance ports are inclined in relation to the axis of the torch.

The torch is placed in operation upon ignition of the electric arc between the electrodes 6, 14 which generally takes place after actuation of thhe systems for supplying the cooling medium and the gas.

3 I claim:

v 1. A plasma torch comprising a generally cylindrical unitary housing formed in its peripheral wall with axially extending channels for the circulation of a cooling fluid; a tubular stem extending axially into said housing from one end thereof; means including a layer of nonconductive material between said housing and said stem for securing said stem to said housing in electrically insulated relationship therewith; a cathode structure having a generally cup-shaped body in fluidtight contact with said stem in said housing; a feeding tube disposed in said stem with annular clearance and extending yinto said body for admitting into same a stream of cooling uid introduced into said stem; an anode structure including a nozzle-shaped electrode disposed in said housing at the other end thereof and confronting said cathode structure, said anode structure further including a guide ring spacedly surrounding said cathode structure to form a gas chamber therewith; an insulating spacer interposed between said guide ring and said cathode structure; retaining means at said other end of said housing for holding said anode structure, said spacer and said cathode structure in position; and conduit means for admitting a gas to said chamber; said nozzle being provided with an outer peripheral groove forming a ring space within said housing communicating with said channels, said layer having a passage connecting one of said channels with said annular clearance for conveying cooling uid from said body to said ring space whence the uid is discharged through another of said channels; said layer, spacer, guide ring and nozzle axially abutting one another under pressure of said retaining means along the inner wall surface of said housing, said channels terminating at the bottom of said inner wall surface in lateral ports at the level of said ring space.

2. A plasma torch as defined in claim 1 wherein said conduit means includes a further axial channel in the peripheral wall of said housing.

3. A plasma torch as defined in claim 1 wherein said layer consists of cast synthetic resin.

4. A plasma torch as dened in claim 1 wherein said stem has a beveled end, said body forming a frustoconical seat for said beveled end.

5. A plasma torch as defined in claim 1 wherein said stem has a cylindrical recess, said body being partly received in said recess, further comprising an O-ring interposed between said body and the peripheral wall of said recess.

References Cited UNITED STATES PATENTS 2,960,594 11/1960 Thorpe 219--75 3,294,953 12-1966 Spies 219-121 3,375,392 3/1968 B'rZOZoWski et al. 313-231 3,116,405 12/1963 Browning et al. 313-231 X 3,198,932 8/1965 Weatherly 219-75 X 3,309,492 3/1967 Fields 219-75 ROBERT SEGAL, Primary Examiner P. C. DEMEO, Assistant Examiner U.S. Cl. X.R.

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