Plasma arc torch, and methods of assembling and disassembling a plasma arc torch

#The present invention relates to plasma arc torches and to methods of assembling and disassembling such torches.

#A plasma arc torch generally comprises a torch body assembly that supports an electrode for emitting an electrical arc that attaches to a workpiece to be operated upon, and a nozzle for directing a flow of a plasma gas toward the workpiece such that the plasma gas stream surrounds the arc. The electrode and nozzle generally are regarded as “consumables” that are subject to deterioration during operation of the torch and that therefore must be replaced periodically in order to restore the torch to a proper condition for satisfactory operation. Typically a plasma arc torch includes a number of front end parts that must be removed in order to gain access to the consumables for replacement. In many existing plasma arc torches, the various front end parts must be removed one at a time, and then reinstalled one at a time after replacement of the consumables. The process thus is relatively inefficient and cumbersome.

#The present invention addresses the above needs and achieves other advantages, by providing a plasma arc torch and methods for assembling and disassembling a plasma arc torch wherein, in one embodiment of the invention, a plurality of front end parts form a unit that is removable from the torch in a single operation to gain access to the electrode. The unit can then be reinstalled in the torch in a single operation after replacement of the electrode.

#Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

#FIG. 1 is a sectioned side elevation of a known shielding gas plasma arc torch;

#FIG. 1A is an enlarged view showing the lower portion of the torch of FIG. 1;

#The present inventions now will be described more fully hereinafter with reference to the accompanying drawings in which some but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

#With reference to FIGS. 1 and 1A, a known plasma arc torch of a type to which the present invention is applicable is broadly indicated by reference numeral 10. The torch can be a shielding gas torch generally as described in U.S. Pat. No. 6,346,685, incorporated herein by reference. The torch 10 provides a swirling curtain or jet of shielding gas surrounding the electric arc during a working mode of operation of the torch. The torch 10 includes a generally cylindrical upper or rear insulator body 12 that may be formed of a potting compound or the like, a generally cylindrical main torch body 14 connected to the rear insulator body 12 and generally made of a conductive material such as metal, a generally cylindrical lower or front insulator body 16 connected to the main torch body 14, an electrode assembly 18 extending through a passage in the main torch body 14 and front insulator body 16 and supporting an electrode 20 at a free end of the electrode assembly, and a nozzle assembly 22 connected to the insulator body 16 adjacent the electrode 20. The main torch body 14 and insulator bodies 12, 16 collectively form a torch body assembly to which various front end parts are releasably attached, as further described below.

#A plasma gas connector tube 24 extends through the rear insulator body 12 and is connected by screw threads into a plasma gas passage 26 of the main torch body 14. The plasma gas passage 26 extends through the main torch body 14 to a lower end face 28 thereof for supplying a plasma gas (sometimes referred to as a cutting gas), such as oxygen, air, nitrogen, or argon, to a corresponding passage in the insulator body 16, as further described below.