Patent ID: 6478992
Filing Date: 2002-11-12
Classification: B29C

Abstract:
An extrusion molding method for a thin tube made of a synthetic resin material wherein a continuous product for a thin tube is formed by plasticizing and kneading a raw material composed of a synthetic resin material by means of an extrusion molding machine, extruding the plasticized and kneaded raw material from a molding die to form a tubular body having a circular cross section, further passing said tubular body on a sizing die to give a final inner diameter to the tubular body, cooling and hardening said tubular body, comprising the steps of:coupling said molding die and said sizing die to each other by a connecting pipe; making said sizing die from a carbon material; supplying a first air to an interior of said sizing die through said connecting pipe; and supplying a second air to an interior of said molding die so that an air-lubrication layer is formed between an inner surface of said continuous product and an outer surface of said sizing die.