Apparatus for stretching a tubular film of thermoplastic synthetic polymeric resin

Claim 1

A suspended internal mandrel apparatus for stretching a tubular film of a thermoplastic synthetic polymeric resin which comprises: a. a mandrel of circular cross section having a surface with a rough finish of 50 to 400 meshes, b. a member extending upwardly from said mandrel to which at least two spaced apart interior rolls are attached, c. at least two exterior rolls disposed at least partially beneath said interior rolls and in abutting and supporting relationship therewith, d. said interior rolls, said exterior rolls and member serving as the sole support means for said mandrel, e. a feed means located above said interior and exterior rolls which is adapted to feed a tubular film of thermoplastic resin downwardly between the abutting surfaces of said interior and exterior rolls, f. a take-up means located below said interior and exterior rolls which is adapted to pull said tubular film from between said interior and exterior rolls and over the mandrel that is suspended beneath said interior and exterior rolls, and g. means for applying heat to said mandrel.