| 摘要 |
PURPOSE:To realize accurate bending process through easy separation between a bulb and a forming drum by bending an annular part with a forming drum of which open end is extending to the axial direction of the annular bending. CONSTITUTION:With the bending part 16 and both ends 21 held respectively by the chucks, the straight part 22, 23 are bent by winding it around a forming drum 24. This forming drum 24 is so configurated that can be divided into two parts in the direction of thickness indicated by the arrow marks and the circumference surfaces of respective divided bodies 25, 26 are formed with the forming grooves 27, 28. The internal circumference surfaces of these forming grooves 27, 28 are curved along the external circumference suface of bulb 11, continuously opened in the side of divided bodies 25, 26 opposing each other and simultaneously extended up to the external side of the line 01-01 connecting the center points of axis of bulb at least at the annular part thereof along the axial direction of the annular parts 14, 15 to be bent. Thereby, accurate bending process can be realized. |
