| 摘要 |
PROBLEM TO BE SOLVED: To prevent a sink mark in the surface of a parison and form a rib normal to the surface of the parison by a method wherein a rib-forming blade, which projects orthogonally to the molding surface of a mold and is movable forward and backward, is provided and the temperature of the blade is held higher than the softening temperature or the melting temperature of a molding resin. SOLUTION: In this molder, a rib-forming blade 20, which passes through a mold 8 and project normal to the molding surface of the mold, and a heater 24 for heating the blade are provided. The heater 24 holds the rib-forming blade 20 at a temperature higher than the softening temperature or melting temperature. At a mold closing, the rib-forming blade 20 is projected within the range that the parison P at the tip part of the rib-forming blade does not come into contact with the opposite side of the parison. After the mold closing, high pressure air us blown in the parison P and the rib-forming blade 20 is gradually retreated in the mold 8. As a result, two projected sheets of rib portion are fused into an integral body by means of the pressing force of the high pressure air, resulting in forming a rib normal to the surface of the parison. Further, since the tip part of the rib does not abut against the opposite side parison, no sink mark develop in the opposite side parison. |
