Robot for electric resistance spot welding - where robot arm carries welding transformer so only short sec. leads are required

摘要

Welding robot for the electric resistance spot welding of sheet metal parts, uses =1 driven, multijoint arm ending in a welding transformer, which is in close proximity to the welding electrode(s) also located at the end of the arm. A flexible cable carries the mains voltage power supply to the transformer, which provides the low voltage used in resistance welding. The mains power supply is pref. fed to a stationary frequency converter so the mains frequency is increased to 200-1000 Hz, esp. 200-400 Hz, before reaching the transformer. Used for mass prodn. spot welding using =15,000 amps. By locating the transformer near the electrodes, the use of long, heavy, water-cooled cables carrying the sec. current is eliminated. The use of an increased frequency provides better inductive coupling of the iron core in the transformer; only a thin, cable of low wt. is needed to carry power to the transformer.