Extrusion system with balanced flow passage

In an extrusion die assembly, used for extruding molten plastic, said die assembly consisting of an assembly of components, a passage constructed in the components of the die assembly, providing a balanced flow throughout the flow path of the die assembly comprising:

• a component in which is housed the passage, said passage having upstream and downstream ends relative to the direction of plastic flow;
• an inlet constructed in the component to form an opening in the component to provide access to the passage, said inlet communicating with a source of flowable plastic to receive said plastic therefrom;
• at least one pair of first and second flow channels constructed in the component in communication with the inlet, said channels forming a joint at the inlet and extending downstream within the component;
• a distribution groove, constructed within the component generally transverse to the direction of plastic flow, said groove forming a chamber to receive flowing plastic, said groove having first and second inlets positioned symmetrically in the chamber and communicating with said first and second channels respectively to receive flowing plastic therefrom, said groove having a downstream edge communicating with an annular outlet to allow flowing plastic to escape therefrom, said groove further comprising a pair of blending means to direct the flow of plastic towards the downstream edge, said blending means positioned symmetrically in the chamber equidistant from the first and second groove inlets;
• and
• a generally conical extrusion channel constructed in the component downstream of the distribution groove to receive flowing plastic escaping from the annular outlet of the groove.