| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method for a seat back frame in which time required for jointing an upper frame with a side bracket is short, in which a plate thickness of the upper frame to be jointed can be thin, and in which light weight and low cost can be achieved. SOLUTION: Both lower end parts 2a, 2a of an upper frame 2 comprising an overturned U-shaped pipe are inserted into tubular parts 3b, 3b formed by winding and bending work at respective upper end parts of a right and a left side brackets 3, 3, and the both lower end parts 2a, 2a of the upper frame 2 are fitted in the tubular parts of the right and the left side brackets 3, 3 to manufacture a seat back frame 1. In this case, a fitting part 7 of the lower end part 2a of the upper frame 2 with the tubular part 3b of the side bracket 3 is nipped by a pair of pressurizing tools 8 from the outer side to be pressed, while a voltage is applied between both pressurizing tools 8, 8, so the fitting part 7 is softened by heat generated by a current flowing at a position pressurized by the pressurizing devices 8, while the fitting part 7 caulked in a recessed form by pressurizing force, thereby the lower end part 2a of the upper frame 2 is jointed with the tubular part 3b of the side bracket 3. |
