Control of thermoplastic injection moulding process - uses sudden rise in pressure signalled by sensor in mould space to indicate end of filling phase, improving prod. quality

摘要

Moulding is controlled by switching from the injection phase to the moulding phase when the mould space is completely filled. The signal is pref. generated by the sharp rise in pressure measured inside the moulding tool. Alternatively, the hydraulic pressure or the nozzle pressure can be used to provide the signal. An injection moulding tool has a pressure sensor fitted in the mould space to provide a signal to a control unit for the hydraulic drive when the mould is full. Alternatively, a pressure sensor in the feed nozzle or a hydraulic pressure signal transmitted by a line can provide the signal for the end of the filling phase. USE/ADVANTAGE - The invention makes the switchcover at the end of the injection phase automatic so that it does not depend on the judgement of the operator and improves product quality.