Patent ID: 7172407

Claim:
A combined plasticizing and injection unit for an injection molding machine, comprising: a housing; an injection nozzle supported by the housing for interaction with an injection mold; an extruder constructed for continuously producing melt and for forcing melt into the injection mold via the injection nozzle, said extruder including an injection plunger supported for movement in a telescopic manner in the housing and defining with the housing anteriorly of the injection plunger an injection space for supply of melt to the injection nozzle, said injection plunger configured to define a barrel and including a melt through channel for feeding the injection space with melt, said extruder including at least one plasticizing screw which is received in the barrel and continuously produces melt and which has an outer thread, and; a valve disposed in the melt through channel and controllable to close the melt through channel wherein the extruder has a passageway to enable melt to backup towards the rear via the outer thread of the plasticizing screw, when the melt through channel is closed by the valve and melt is injected into the injection mold by the injection plunger of the extruder.