| 摘要 |
PURPOSE:To manufacture a highly accurate thin-plate poly V-pulley, by preliminarily forming a basal edge part at the connecting part of peripheral wall and bottom wall of a cuplike material before corrugating the peripheral wall of the material. CONSTITUTION:A bottomed cylindrical cuplike material 1 is formed from a circular material made by blanking a steel plate. This material 1 is supported by a pair of upper and lower rotary preliminary forming dies 13, 14. While rotating the forming dies 13, 14, the inner and outer peripheral faces of peripheral wall 4 of the material 1 are supported by the roll face 14a of the forming die 14 and the roll face 15a of the side wall preliminary forming roll 15. At the same time, the forming roll 13 is lowered to press the peripheral wall 4 to the axial direction, and an opening edge part 6' is formed in an opening side edge part 4a. Then, the forming die 13 is further lowered and the connecting part 4b of the peripheral wall 4 is pressed and worked by the basal edge preliminary forming part 13b of the forming die 13 and the basal edge preliminary forming part 15c of the forming roller 15 to form a basal edge part 7'. Then, crest parts and trough parts are formed on the peripheral wall 4. |
