MIG-PLASMA WELDING

摘要

A system and method for welding combining plasma welding and MIG (Metal-Inert-Gas) welding. The system includes a plasma torch having a constant-current power supply (49) to make a non-consumable plasma electrode (38) negative with respect to the workpiece (31), and also includes a MIG arc torch having a constact-voltage power supply (48) to make a filler wire (39) positive with respect to the workpiece (31). A separating body between the plasma electrode and the filler wire, preferably in the form of a nozzle (33) substantially surrounding the plasma electrode (38), guides a gas flow past the surface of the plasma electrode. Optionally, an auxiliary power supply maintains an arc between the non-consumable electrode (38) and the separating body to facilitate the starting of the main arcs and to prevent thermal shock to the plasma torch when the main arcs start. The welding system is moved relative to the workpiece (32) such that the plasma arc precedes the MIG arc (40).