Gas plasma (argon, helium or similar) arc welding of light metal alloy parts, in which voltage pulses are applied to the welding electrode and to the part being welded

摘要

The electrical current supply is direct current and the electrode is connected to the positive pole and the part (138) to be welded to the negative pole. The part is electrically insulated from earth. The immediate end environment of the rod shaped electrode turned towards the part is maintained at the potential of the part. Voltage pulses are applied to the electrode and to the part being welded. A welding torch (100) has a nozzle (36) through which the gas plasma flows. The nozzle, made from a good electrically conducting material, surrounds the non consumable rod electrode which is electrically insulated from the nozzle. The rod is connected to the positive pole of the d.c. source and has a connection connected to the second pole of the d.c. source. A high frequency lighting device (135) is connected to the electrode and to the part (138) to be welded. The positive pole of the d.c. source is oriented along the nozzle axis and is connected to the part (138) via a high value resistance (1R2) whose value is in the range 10<3> to 10<6> ohms, preferably 10<5> ohms. The part to be welded is insulated from earth potential. The d.c. supply uses a capacitor bank (130) connected to a charging circuit (131,132). Its output being connected to the rod electrode of the welding torch. An electrical supply unit (136) includes a rectifier and is connected to the capacitor bank.