| 摘要 |
PURPOSE:To form exactly at a low cost a desired number of V-crest lines without increasing the thickness of a cylinder part by making a bottomed cylinder descend by a cylinder part compression die, fitting and inserting the cylinder part into an inner die, and repeating an overhang groove forming process for compressing it in the shaft center direction by an outer grooved split die. CONSTITUTION:A bottom part of a drawing cylinder 10 placed on a spring 7 energizing hanging part 6 of a lower die is inserted and held by a cylinder part compression mold 9 of an upper die and made to descend. The cylinder part is fitted and inserted into an inner mold 5, also an outer grooved 19 split die 11 which has been held so as to be separated from each other by a spring of the upper die is compressed in the shaft center direction by a supporting die 12 with a tapered surface, and an overhang groove 18 is formed in the cylinder part. By repeating this process, a desired number of V-crest lines are formed on the cylinder part. In this way, a V-crest groove having a desired number of lines is formed exactly at a low cost without increasing the thickness of the cylinder part, with respect to the bottom cylinder 10. |
