| 摘要 |
PROBLEM TO BE SOLVED: To properly pressurize a welding projection of a projection nut to a steel sheet component, and to minimize displacement of the steel sheet component due to electrode pressurization.SOLUTION: At least surface side welding electrode pairs 100A and reverse side welding electrode pairs 100B are arranged, and advance force of lower advance-retreat driving means 8A of the surface side welding electrode pairs 100A is set stronger than advance force of upper advance-retreat driving means 9A, and a stroke of a lower electrode 5A is set to be a length enabling an upper end face of the lower electrode 5A to be brought into close contact with a reverse surface of a steel sheet component 10, and a stroke of an upper electrode 6A is set to be a length enabling the steel sheet component 10 and the nut 1 to be continuously pressurized, and also in the reverse side welding electrode pairs 100B, the advance force and the advance length of the upper advance-retreat means 9B and the lower advance-retreat driving means 8B are set inversely to the surface side welding electrode pairs 100A. |
