Manufacture of hollow bodies by extrusion and blowing a thermoplastic resin uses blowing mould and mobile die with channel for pressure fluid

摘要

The procedure consists of heating the resin to a malleable state and filling a space (12) in a heated accumulator (1) with a portion of it. After fitting a blowing mould (24) beneath the accumulator a mobile die (10, 11) is used to carry a layer of resin into the mould as an outer surface coating (38). A pressure fluid is then fed through a channel (17) and outlets (39) in the die to expand the resin against the inner surface of the mould. The resulting hollow body is then allowed to cool until rigid and ejected from the mould after retracting the die.