This invention relates to a plasma cutting system of improved efficiency and safety. The improvements of the invention each taken alone or in combination add to operator convenience and productivity and provide equipment portability.
Union Carbide Corporation, Linde Division, Technical Sales Manual, January 1983 entitled "PRODUCTOR AUTOMATIC SHEET METAL SYSTEM" discloses a computer aided manufacturing system having two parts, a cutting center and an input control terminal. The cutting center consists of a gantry type machine with microprocessor numerical control, a plasma cutting system, one or more down draft cutting tables and a fume-smoke collector.
McNabb in U.S. Pat. No. 3,433,923 and McNabb in U.S. Pat. No. 3,433,922 each discloses an electronic beam welding machine in which an electron beam emitter is heated electrically to provide a focused beam of electrons.
Malmuth et al in U.S. Pat. No. 4,121,087 discloses an apparatus for laser welding which uses power reflected by the surface being welded to control the power input to the weld.
Bateman in U.S. Pat. No. 2,927,992 discloses automatic electric arc welding at a uniform rate along a contoured part.
Takizawa et al in U.S. Pat. No. 4,270,845 and Duruz in U.S. Pat. No. 4,412,120 each discloses a machine for cutting sheet metal by means of a laser beam. In Duruz the sheet metal is placed on a support constituted by a container which moves on a table of the machine while rolling on support balls provided on the table.
Connon et al in U.S. Pat. No. 3,417,222 discloses cutting or drilling nonconducting material with a high energy beam of electrons. The beam is focused into a vacuum work chamber.
Balfanz in U.S. Pat. No. 4,234,777 discloses a programmed welding machine including welding heads carried on a motor driven bridge.
Cecil et al in U.S. Pat. No. 4,010,346 discloses a self-propelled tractor for a welding and cutting apparatus. The tractor has drive and steering wheels.
A common form of metal cutting is on a stationary table requiring the operator to position the metal sheet under the cutter while being exposed to fumes produced during prior cuttings. Such equipment requires loading and cutting in the same location. The present invention improves upon this type of equipment by providing a mobile system including a loading area which is separate from an enclosed cutting area of the machine into which the operator need not enter.