FOUR-ARC WELDING METHOD Russian patent published in 1997 - IPC

FIELD: mechanical engineering; line welding of steel structures, such as large diameter tubes. SUBSTANCE: first, second and fourth arcs in direction of welding are supplied from separate ac sources, with arc currents shifted in phase through 120 degrees relative to each other. Third arc is supplied from DC source. When welding an article insulated from earth, optimum variant of welding is connection of return conductors from DC source to front end of workpiece and those from ac source, to rear end of workpiece. EFFECT: improved quality of weld. 2 cl