Production of bodies from synthetic plastics materials

Claim 1

Apparatus for use in the moulding of synthetic plastics material, the apparatus comprising a chamber, feed means including a barrel and a member movable therein to plasticise synthetic plastics material supplied to the barrel and to feed said plasticised material into the chamber, mould means defining a series of intercommunicating mould cavities, the series having an input end and an output end, a nozzle interposed between said input end and the chamber to feed plasticised synthetic plastics material into the mould cavities of the series at the input end, means for causing relative movement between the nozzle and the series so as to enable mould means to be moved from the output end of the series to be inserted, after it has been emptied, at the input end of the series to provide an empty mould cavity and then brought into engagement with the nozzle, a valve associated with the nozzle, means to open the valve for passage of said plastic material through the nozzle to the mould means when the nozzle is engaged by said mould means at said input end and to close said valve when the nozzle is disengaged from said mould means at the input end, and means for varying the volume of the chamber while maintaining plasticised synthetic plastics material therein under pressure while the valve is open and the nozzle is in communication with the chamber, whereby plasticised synthetic plastics material passes through the nozzle into the series of mould cavities to fill voids left by shrinkage of the material in such cavities as the material solidifies.