METHOD AND APPARATUS FOR COOLING HOLLOW MOLDED PRODUCT

摘要

A method of forming a hollow product in a molding apparatus having an upstream and a downstream end comprises extruding a parison of thermoplastic material in a molten state from a heated extruder at the upstream end and moving the material through a product shaping region towards the downstream end of the apparatus. The material is cooled by passing a cooling medium internally of the product from the downstream end towards the upstream end of the apparatus.