Moulding device

Moulding equipment for injection compression moulding plastic parts via the injection of a molten thermoplastic resin, comprising:

• a mould which comprises at least two mould halves, which when closed together produce a cavity;
• a moveable core, which, when the mould halves are in the closed position, is moveable relative to the first and second mould halves by a positioning device, wherein at least one mould half contains the moveable core;
• and
• a control system comprising an adjustable positioning device to control the movement of the moveable core using the active control of the cavity pressure,
• wherein the control system is configured to:
• position the moveable core in a start position prior to the injection of the molten thermoplastic resin, in which start position the cavity size and form is equal to that of the product to be produced,
• upon injection, hold the moveable core in the start position by a predetermined back pressure exerted on the rear side of the moveable core, and
• during injection of the molten thermoplastic resin into the cavity, measure the cavity pressure and adjust the adjustable positioning device on the basis of the measured cavity pressure to move the moveable core as a function of the measured cavity pressure in order to increase the cavity size, and
• at the moment that the injection flow rate of the resin drops, return the moveable core to the start position in a controlled fashion and as a function of the cavity pressure, wherein in this start position the mould cavity is again identical in dimensions to the size and form of the product that is produced.