US 6,982,397 B2
Tig welding apparatus and method
Minoru Yamada, Yokohama (Japan); and Akio Tejima, Yokosuka (Japan)
Assigned to Ishikawajima-Harima Heavy Industries Co., Ltd., (Japan)
Filed on Dec. 19, 2003, as Appl. No. 10/741,990.
Claims priority of application No. 2003-316514 (JP), filed on Sep. 09, 2003.
Prior Publication US 2005/0051525 A1, Mar. 10, 2005
Int. Cl. B23K 9/09 (2006.01)
U.S. Cl. 219—130.51 18 Claims
OG exemplary drawing
 
1. A TIG welding apparatus comprising; a twin electrode type welding torch having a first and a second welding electrode arranged approximately parallel and either side of an insulation plate of a predetermined thickness, and a main unit which supplies to the first welding electrode a first welding current varied at a first period, and to the second welding electrode a second welding current varied at the first period and at an opposite phase to the variation of the first welding current, wherein said main unit superimposes a variation of a second period being shorter than the first period, onto the first and second welding currents.