| 摘要 |
This invention suppresses the deformation of a molded body due to mold releasing. A back part molding die comprising a plurality of die portions is used, said plurality of die portions including a first die portion which forms, among the internal surface of the back part molding die, a first partial internal surface that spans one turn in the circumferential direction, and a second die portion which is disposed more to the forward extremity side in the axis line direction than the first die portion and which forms, among the internal surface of the back part molding die, a second partial internal surface that spans one turn in the circumferential direction. At mold releasing time, by starting to move the first die portion toward the back extremity side relative to the back part molded portion, and, after starting to move the first die portion, by starting to move the second die portion toward the back extremity side relative to the back part molded portion, the back part molding die is disassembled into a plurality of die portions. Alternatively, the back part molding die may comprise a plurality of die portions, each forming, among the internal surface of the back part molding die, a different portion from one another. |
