Abstract: Apparatus and method for use in a plasticating extruder of the type having an axially extending elongate barrel for preparing a plasticated material from solids introduced into the extruder wherein an axially extending screw conveyor continuously conveys material in a downstream direction as the material is melted within a channel in the screw conveyor, the channel extending between a leading face and a trailing face on a flight of the screw conveyor such that a solid bed of material is established and melting takes place to form melted material within a relatively thin melt film established between the solid bed and the barrel, the melted material passing progressively from the melt filn into a melt pool formed at the leading face of the flight, and melted material is transferred within a conduit in the screw conveyor from the melt pool to the solid bed, whereby the transferred melted material is forced into intimate contact with unmelted material in the solid bed to heat the unmelted material and accelerate

Abstract: Plasticating extruders in which increased melting effectiveness is attained through multiple stages including at least one inner screw conveyor within an outer screw conveyor in a barrel for receiving unmelted solid material from the channel of the outer screw conveyor and conveying the received unmelted solid material in the channel of the inner conveyor in a direction parallel to and axially coextensive with the direction of travel of the material in the channel of the outer screw conveyor and melting the received unmelted solid material to bring melted material to a downstream location where the melted material from both channels merges to deliver a flow of fully melted material to a downstream discharge outlet. A vent may be located in the barrel in the vicinity where material enters the channel of the inner screw conveyor for improved venting as a result of the diversion of material away from the vent.

Abstract: A plasticating extruder screw conveyor includes multiple primary flights and corresponding multiple secondary flights defining multiple channels on the screw conveyor arranged about the longitudinal axis of the screw conveyor such that radial components of forces between the screw conveyor and unplasticated material located in the channels are substantially balanced so as to reduce to a minimum any resultant radial force upon the screw conveyor and any concomitant lateral deflection of the screw conveyor, thereby reducing or eliminating excessive vibration, wear or galling of the screw conveyor.

Abstract: A plasticating extruder in which the screw conveyor includes an inner backfeed passage communicating with the channel established by the main flight of the screw conveyor and a solids-directing flight for directing unplasticated material into the backfeed passage and segregating already-plasticated material from the unplasticated material in the channel.

Abstract: Apparatus and method in which the temperature of the barrel inner surface and the temperature of the screw conveyor outer surface of a plasticating extruder are varied, alternately, in repeated steps, independent of one another along at least a portion of the solids conveying zone of the extruder, while a production effectiveness parameter simultaneously is monitored, until the monitored production effectiveness parameter is optimized and the production effectiveness of the extruder is at a desired maximum.

Abstract: A plasticating apparatus operates continuously to plasticate material which is delivered intermittently to a molding device, the plasticating apparatus including a first screw conveyor which rotates in a barrel, a backfeed passage within the first screw conveyor and a second screw conveyor in the backfeed passage arranged to recirculate material in a circuit extending back through the backfeed passage. The first screw conveyor reciprocates axially so that during periods of non-delivery of plasticated material, the capacity of the circuit is increased to accommodate the accumulation of added plasticated material generated by the continuous rotation of the first screw conveyor.

Abstract: A cross-head die in which the manifold is provided with means for selectively varying the volume of the manifold at some locations relative to other locations, whereby the relative wall thickness about the annular configuration of the material flowing through the die is selectively adjusted about the periphery of the annular configuration of flowing material. Wall thickness and configuration are further controlled at the outlet orifice of the die by means movable to selectively expand, contract and alter the annular configuration of the die passage at the orifice.

Abstract: Apparatus and method for preparing a plasticated material from solids introduced into the apparatus, the apparatus including a barrel having a screw conveyor defining a channel for conveying the material in a downstream direction as the material is melted, the channel including a solids conveying zone and a melting zone downstream from the solids conveying zone, the apparatus and the method including, respectively, means and the step of providing an abrupt change in the volume of the channel at a specified location between the solids conveying zone and the melting zone for inducing the formation of a melt pool in the channel at that location.