Patent ID: 6908581

Claim:
A method of co-extruding a plurality of plastic material flowing streams into a mold cavity to produce a molded product, comprising the steps of: combining inner and outer streams of covering plastic materials with at least one interior stream that is to serve as an interior core of a resulting molded plastic product; forcing the combined streams to flow along annular flow paths to form an annular interior stream and inner and outer annular streams of covering plastic materials, with the annular interior stream encased within the inner and outer annular streams of covering plastic materials; controlling the flows of the annular interior stream and the inner and outer annular streams of covering plastic materials so that: a portion of the annular interior stream has a flow velocity that is greater than an average velocity of the combined streams; the portion of the annular interior stream reaches a region adjacent to a flow front of the combined streams; and the portion of the annular interior stream does not flow along or across a zero-velocity-gradient streamline of the combined streams.