Electric heating – Metal heating – By arc
Patent
1996-06-10
1998-02-17
Paschall, Mark H.
Electric heating
Metal heating
By arc
219 75, 21912136, 2191215, B23K 1000
Patent
active
057193703
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to electric-arc generators of low-temperature plasma, that is, to plasma-steam torches and can find application in mechanical engineering, as well as in the motor, aircraft, electrical-engineering and other industries for performing diverse kinds of plasma treatment, such as cutting, welding, and heat-treatment of the surfaces of various materials.
More specifically the invention relates to those low-temperature plasma generators (plasmatrons) which make use of steam as the working medium.
BACKGROUND ART
Known in the prior art are plasma generators making use of steam as the working medium. In this case steam may be supplied to the generator from a special source or be produced immediately in the generator due to high temperatures therein. Besides, the steam generating process may be combined with heat withdrawal from the plasmatron electrodes.
A widespread technical solution to the problem of carrying out said process is admission of the liquid being evaporated through passages in the electrodes, said liquid evaporating while flowing along said passages, at the same time cooling the electrodes (PCT FI 88/00427: FR, A, 1,620,032).
The prior art closest to the herein-proposed solution is the construction of a plasma torch as taught in RF Patent 1,731,029. The plasma torch comprises a housing which accommodates coaxially arranged a nozzle anode and a central rod-shaped cathode fitted in a holder encompassed with a cylinder made of a heat-conducting material and provided with tangential passages. Connected to the housing is a container for a liquid coolant, filled with a moisture absorbent that encompasses a porous tube forced onto the cathode holder.
When an arc is stricken across the electrodes, heat energy released thereby causes the liquid coolant to boil, and the resultant steam escapes through the tangential passages into the discharge chamber and further on, as a plasma jet, through a central axial port of the nozzle anode.
The torch discussed before suffers from a restricted electrode cooling abilities, that is, it fails to provide heat abstraction when the nozzle-anode-to-cathode distance exceeds 1.5 to 2 mm. At a larger distance the arc power and the amount of heat evolved on the electrodes increase so that cooling of the cathode becomes inadequate, whereby the cathode is liable to get destructed rapidly. On the other hand, restriction of the interelectrode distance to the aforesaid values reduces the working range of the torch power output.
DISCLOSURE OF THE INVENTION
The present invention has for its principal object to provide an electric arc plasma-steam torch featuring an efficient cooling of electrodes within an extended range of power output.
The foregoing object is accomplished due to the fact that in a plasma-steam torch, comprising a housing which accommodates coaxially arranged a nozzle anode and a rod-shaped cathode made fast in a holder, said housing being connected, through a pipe connector filled with a porous heat-conducting material, to a container for a working fluid, filled with a moisture absorbent that encompasses a tube made of a heat-conducting material, said tube having a flange with passages at its end facing the nozzle anode and accommodating said electrically insulated cathode holder, according to the invention, a sleeve is interposed between the tube flange and the nozzle anode, said sleeve being made of a heat-conducting material and having passages on its end surface facing the nozzle anode and on the outside cylindrical surface thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
The essence of the present invention is illustrated by the accompanying drawings, wherein:
FIG. 1 shows a schematic general view of the torch;
FIG. 2 shows the torch housing;
FIG. 3 is a section taken along the line AA in FIG. 2; and
FIG. 4 is a view of the sleeve on the arrow B.
BEST EMBODIMENT OF THE INVENTION
The torch has a housing 1 accommodating coaxially arranged an exit nozzle anode 2 and a rod-shaped cathode 3 made fast in a holder 4. T
REFERENCES:
patent: 4743734 (1988-05-01), Raboti
patent: 5247152 (1993-09-01), Blankenship
Apunevich Alexandr Ivanovich
Titarenko Evgeny Ivanovich
Adamas AT AG
Paschall Mark H.
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