MOLDING DIE FOR BLOW MOLDING PREVENTING UNEVEN WALL THICKNESS

摘要

PURPOSE:To eliminate an uneven wall thickness of a blow molding hollow body by attaching a nonmetallic heat insulating material to the part which a parison inside a metal mold touches initially. CONSTITUTION:A nonmetallic heat insulating material 7 is attached to the part A which the parison inside 2' of blow forming metal dies 3' and 4' touch initially so as to prevent hasty cooling of a parison touching part. The heat insulating material 7 is made, for instance, of woven fabric such as ethylene tetrafluoride polymer which is woven in such as manner that many fine hairs 7' are erected on the surface thereof. On the occasion of forming, the parison 5 heated at a fixed temperature touches initially the part A inside 2' of the metal mold. However, it touches the inside 2' of the metal mold through the intermediary of the heat insulating material 7 and therefore the surface of the parison 5 is not cooled hastily, thereby the viscosity thereof is also kept in a low state. Accordingly, the parison 5 keeps its fluidity and is extended fully evenly at the part A, thereby the parison is shaped having a hollow state of uniform wall thickness throughout the inside surface of the metal mold.