Injection moulding machine for thermoplastic resin products - has worm pressure head sealed outside with non-return ball valve

摘要

An injection moulding machine, for synthetic material prods., has a section for holding the parts of the mould which opens and closes, and a plasticising unit. This has a worm for transporting and injecting the synthetic material into the mould; the point of the worm forming a pressure head with channels for the passage of the plasticised resin and a non-return valve. In the pressure head there is a central bore running in the axial direction of the worm. Two channels open into the end of the bore nearest the worm, and at the centre of the pressure head the bore widens out into a chamber. In this, three ribs extend axially almost its full length, and act as guides for a freely moving ball which has a larger dia. than the bore. A non-return valve is formed for holding the pressure in the mould. It is cheap to produce and is not subject to wear. It cannot tilt and jam thus becoming useless.