GB929760A - Improvements in or relating to arc torches - Google Patents

Abstract

929,760. Arc torches. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Aug. 26, 1959 [May 29, 1958], No. 17125/58. Class 39 (3). A high temperature arc torch includes a pipe member having an exit nozzle; an internal electrode within and coaxial with the pipe member and insulated therefrom; means for initiating and maintaining an arc between the said internal electrode and the pipe or nozzle or an external electrode, the diameter of the nozzle orifice being sufficiently small to constrict the diameter of the arc and the walls of the pipe member having formed therein one or more channels for the circulation of a coolant around the nozzle; means for passing a stream of fluid into the arc stream and out through the nozzle to form a jet and an adjustment or feed mechanism for moving the internal electrode to control the length of the arc. In the apparatus shown an electrode 3 is held in a composite pipe member 1 by a collet 25 having jaws 27 surrounded by a chuck body 18. A rotatable member 32 keyed to the collet 25 enables the electrode 3 to be released and its position adjusted by rotating an insulating cap 37 carrying a screw-ring 43 which engages the external thread of a collet 39 having jaws which are clamped around the electrode 3 by a chuck ring 41. The nozzle portion 4 of the pipe member 1 is cooled by a coolant entering and leaving through pipes 12 or 13. The body portion is cooled by a coolant which enters and leaves a cavity 21 through pipes 22 or 23. A fluid (gas, vapour or liquid, which may contain powders) is supplied to an inlet pipe 2 and passes through passages 29 to a duct 26 surrounding the electrode 3 and thence through grooves in the jaws of the collet 27 to the nozzle 4. An external magnetic or electrostatic field may be supplied around the nozzle 4. The single electrode 3 may be replaced by a group of electrodes which may have individual co-operating nozzles. A secondary nozzle may be attached to the primary nozzle 4 and may have an orifice in its wall through which a reactive fluid such as oxygen or nitrogen can be injected. A highfrequency vibration may be applied to the members containing coolant channels to remove steam bubbles or deposits. Reference has been directed by the Comptroller to Specifications 826,106, 842,397 and 863,189,