Importance

Loading Importance Indicators...

Abstract

Energy-efficient apparatus for blow moulding articles from thermoplastic material includes a mould 2 defining a mould cavity 3 for receiving a heated thermoplastic parison 4. An air duct 9 connects the mould to a low pressure accumulator 10 containing air at a first moulding pressure for use in a first blowing stage, at least one intermediate accumulator 20, 30, containing air at intermediate pressures for use in intermediate blowing stages, and a high pressure accumulator 40 containing air at a final moulding pressure for use in a final blowing stage. The capacity of each of the accumulators is about ten times greater than the volume of the mould cavity. Valves 11-41 selectively control communication between each of the accumulators and the mould cavity 3 to admit air from each of the accumulators to the mould cavity in sequence during a blowing phase, and thereby expand the parison in a stepwise manner. During a recovery phase, the valves sequentially admit pressurised air from the mould cavity to the intermediate and low pressure accumulators 30-10 in turn to restore the accumulator pressures for the next moulding cycle.

Loading the Abstract Image...

First Claim