MOLDING SIZING DIE FOR THERMOPLASTIC RESIN MANDREL

摘要

PROBLEM TO BE SOLVED: To stably mold a mandrel which can be manufactured without using a lubricating oil and equipment concerned with it, and has only a little strain in the sectional shape even when the molding speed is made faster. SOLUTION: A sectional area ranging from an inlet side of a sizing die to an outlet is drawn in stepwise. The drawing-in is performed such that a relationship between an inlet sectional area (a) of the sizing die and a sectional area (b) of an intermediate position 2b whose distance from the inlet of the sizing die is 0.8-2.5 times an outlet diameter satisfies a/b=1.1-1.5. Further, the length from the intermediate position of the position 2b to the outlet is set to be 3-15 times the outlet diameter, and a ratio between the sectional area (b) and an outlet sectional area (c) is drawn in so as to satisfy b/c=1.05-1.5.