Importance

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Abstract

Multiple lumen tubing is extruded by first extruding an inner tube of molten plastic about a metallic, bore-forming mandrel wire, followed by extruding about the inner tube an outer tube of molten plastic having a lumen formed by air mandrel means, with the inner and outer tubes being bonded together. This may be accomplished by means of a mandrel which is positioned in an extrusion die, with the mandrel defining a distal end portion positioned and shaped to form a lumen in the tubing, and an air flow passage extending through the mandrel to provide an air mandrel to the newly formed lumen to prevent its collapse. The distal end portion of the mandrel may be carried by an intermediate neck portion which has at least one transverse dimension that is less than the corresponding transverse dimension of the distal end portion.

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First Claim