Apparatus and method for coextruding materials having different temperature dependent properties

A coextrusion apparatus, comprising:

• at least first and second extruders for coextruding first and second materials, respectively, said first and second materials having generally different temperature dependent properties;
• a profile die having a land section for forming said first material being extruded from said first extruder;
• a feed back formed with a generally circular-shaped mounting opening, said feed block being a generally flat member having front and rear surfaces, a pair of side surfaces, a top surface, and a land section, said mounting opening passing through said front and rear surfaces and including a flared portion adjacent to said front surface, said feed block being formed with a threaded adjustment opening passing through said top surface and communicating with said mounting opening, said threaded adjustment opening threadably engaging a manually adjustable set screw, said feed block further being formed with a pair of spaced channels in said feed block front surface, said front surface abutting said profile die, said mounting opening communicating with said land section of said profile die via said feed block channels, each of said feed block channels including an upper portion and a lower portion, said upper channel portion having a width less than the diameter of said feed block mounting opening and said lower channel portion continuously increasing in width from the width of said upper channel portion in a direction away from said upper channel portion;
• and
• a metering tube formed with open first and second ends and a continuous bore, said metering tube first end being formed with a flared flange and further being manually rotatably adjustably mounted in said mounting opening, said metering tube open second end communicating with said second extruder for receiving said second material, said metering tube first end flange having a flat end face formed with a pair of spaced, radially oriented gates, said metering tube flared flange matingly engaging said mounting opening flared portion and said flat end face being generally flush with said feed block front surface and abutting said profile said metering tube gates communicating with said continuous bore and passing through an external surface of said tube, said metering tube gates each having a width at the inside diameter of said tube generally equal to the width of said upper channel portion of each of said feed block channels, and a width at the outside diameter of said metering tube generally twice that of said inside diameter width, said pair of gates being selectively alignable with said pair of feed block channels for regulating the amount of said second material passing through said aligned gates and channels from said bore and subsequently contacting said first material at said land section of said profile die, said set screw being capable of locking said metering tube in a selected rotational position, said metering tube thermally isolating said second material from said first material prior to contact therebetween, so that a coextruded article is formed combining said different first and second materials.