Pressure-holding chamber type injection moulding process - has nozzle passage enlarged in vol. interrupted midway by a valve in communication with interior of the body, during pressure holding step

摘要

A system of injection-moulding a super-precision prod. is characterised by the material pressure-holding step with additional features in that a nozzle passage enlarged in volume, extending from the machine body to a cavity gate is interrupted midway by a valve from communication with the interior of the body, after the injection step but during the pressure-holding step. The pressure-holding step is carried out using the valve, exerting an internal pressure on a forward portion of the injected material sepd., and compacted in a fixed closed space limited by the valve. An instantaneous remetering step is carried out such that the material in the fixed space is adjusted to a predetermined value in amt. in every shot by regulating its internal pressure to a corresponding value with a possible excess part of the material being discharged out of the machine system.