| 摘要 |
A pair of upper and lower electrode wheels (1, 2) are disposed so that their axes (17, 18) are tilted in a horizontal plane in respective directions opposite to each other with respect to a straight line (Y) perpendicular to a welding line (X) defined on overlapping portions (L) of two metal plates (5, 6), and mash seam welding is performed while positively driving electric motors (61, 62). This can reduce the increased amount of thickness and step gradient of a joint portion to reduce a stress concentration factor to ensure a high degree of joint strength. The metal plates are joined to each other such that a nugget (N) is not deviated from a joint interface. The respective tilting directions of the axes (17, 18) of the electrode wheels (1, 2) are made to face in the horizontal plane toward the extending direction of a metal plate with which the electrode wheels (1, 2) first come into contact. Therefore, it is possible to prevent respective ends of the metal plates at the overlapping portions L from biting into and scratching the corresponding electrode wheels (1, 2) and to prevent the occurrence of spattering during the welding. |
