Apparatus for throttle-valving control for the co-extrusion of plastic materials as interior core streams encased by outer and inner streams for molding and the like

Apparatus for co-extruding multiple plastic materials as for injecting through a gate region into a mold cavity to produce a molded product, having, in combination, plastic material flowing stream sources;

• means for combining streams of such flowing plastic materials with at least one interior stream that is to serve as an interior core of a resulting molded plastic product within interior and outer streams of plastic material to serve as covering plastic material layers;
• a longitudinally extending hollow extruder connected to the combining means to receive the outer and interior streams;
• flow restrictor disposed within and along the extruder to force the combined streams to flow along concentric annular flow paths within and along a longitudinally extending tubular extruder to the cavity gate region, with the annular interior core stream encased by inner and outer annular covering plastic material stream layers;
• the mold cavity at the gate region being shaped for splitting the concentric annular streams along opposite transverse directions to inject into corresponding opposite transverse sections of the cavity.