Plasticating apparatus for molding devices

Claim 1

Apparatus for plasticating material to be delivered intermittently to a molding device, said apparatus operating continuously during periods of delivery and non-delivery of plasticated material, said apparatus comprising: a barrel; a first screw conveyor in the barrel, said first screw conveyor including a flight defining a channel for continuously conveying the material in a downstream direction as the material is melted within the channel, said flight having a leading face facing downstream and a trailing face facing upstream, said channel extending between the leading face and the trailing face; a backfeed passage within the first screw conveyor, said backfeed passage communicating with the channel at a downstream location and at an upstream location to establish a circuit along which the material will move through the channel and the backfeed passage; a second screw conveyor located in said backfeed passage and arranged to convey material from the downstream location to the upstream location so as to enable recirculation of material along the circuit through the backfeed passage and the channel during continuous rotation of the first screw conveyor and intermittent delivery of plasticated material to the molding device; the first screw conveyor having a downstream terminal end and being mounted for axial movement relative to the barrel such that movement in the upstream direction will increase the capacity of the circuit to accommodate added plasticated material to be accumulated within the circuit as the first screw conveyor continues to rotate and generate the added plasticated material during periods of non-delivery of plasticated material to the molding device.