An extruder apparatus with an extrusion screw having an end member which blends molten and solid thermoplastic materials moving through the apparatus into a uniformly fluxed consistency, and a method for uniformly fluxing and blending thermoplastic materials. The extrusion screw end member is provided with a conical terminus forming an annular shoulder with openings extending therethrough.

Apparatus for plasticizing and injecting mouldable synthetic material is disclosed. The apparatus comprises a cylindrical member having a longitudinal cylindrical bore therein into which such material is introducible, nozzle means firmly secured to one end portion of the cylindrical member and communicating with the cylindrical bore, a worm shaft mounted in the bore to be axially and rotatably displaceable relative to the cylindrical member and provided with an opening of circular cross-section extending longitudinally of the shaft from an end face thereof facing the nozzle means, and a closure body firmly secured to the cylindrical member and projecting into the opening, the closure body providing a seal between the opening and the longitudinal cylindrical bore. Advantageously, the apparatus is provided with valve means disposed at the end portion of the worm shaft which is next adjacent the nozzle means to restrain flow of such material along the cylindrical bore in a direction away from the nozzle means.

An extruder for the manufacture of concrete slabs, particulary hollow slabs, in a movable relationship with a casting mold. The extruder includes a feed hopper, at least one feeder, particularly an auger for generating internal pressure in the cast concrete, and at least one core member for generating a desired slab cross-section. The extruder in accordance with the invention has an assembly of at least one contoured core section which performs a combined movement of oscillatory rotation and longitudinal reciprocation to generate inside the molding space a compacting shear action in the concrete mix. The extruder in accordance with the invention is especially applicable for the production of profiled concrete objects with elongated shape at low noise and vibration levels.

A thermosetting resin injection molding machine and method wherein a shearing and kneading barrier is formed at one end portion closer to the injection nozzle of a screw device in a heating cylinder for imparting the shearing forces to and kneading the molding compound so that the molding compound may be sufficiently kneaded before injection and may be uniformly raised in temperature immediately before injection.

Redistributive mixing is effected in an extruder wherein the extruder screw advances thermoplastic material toward and through transfer grooves in a corotative torpedo. The torpedo grooves progressively diminish in cross sectional flow area from inlet ends at the upstream end of the torpedo toward downstream ends running out adjacent to the torpedo tip. Feeder grooves in a complementary passage wall of a stationary discharge head adapter in which the torpedo operates, receive the thermoplastic material transferred and propelled with redistributive mixing action from the torpedo grooves. The passage wall grooves have upstream entry ends aligned with the upstream ends of the torpedo grooves and extend therefrom in progressively increasing cross sectional flow area to downstream ends feeding toward an outlet.