| 摘要 |
PURPOSE:To assure effective electric current sufficiently and to form good nuggets in the stage of series spot welding of a thick material and a thin material by insulating the parts corresponding to the respective electrodes on the rear surface of the thick material electrically to each other. CONSTITUTION:A thick plate 1 and a thin plate 2 are superposed and a back-up member 4 is brought into abutment on the rear surface 3 of the plate 1. Electrodes 6, 7 are brought into abutment on the surface of the plate 2. Further, the parts 8, 9 corresponding to the electrodes 6, 7 of the plate 1 are parted to each other with respect to the direction perpendicular to the thickness direction, whereby the generation of reactive current is prevented. Therefore, effective current Ib is increased and good nuggets are obtained. A backup electrode 10 projecting toward the rear surface 3 in the position corresponding to the electrodes 6, 7 is provided to the member 4 to increase the current density of the effective current Ib. |
