Pressure injection molding of plastic

摘要

When injecting plastic melt into the mold (1), before gas (or liquid) injection to form a gas cushion (8), the cavity is completely filled and pressurized so that the plastic is in a state of precompression during the initial setting phase. Preferred Features: A set delay intervenes between completion of melt injection (3) and introduction of the pressurizing gas (7). It is introduced a given time after the onset, or alternatively after the completion of melt dwell-pressurization. The pressurization gas is introduced in accordance with the hydraulic pressure, or the mold cavity (2) internal pressure. It may be introduced in accordance with the molding surface temperature or the pressure of the injection screw piston (5).