Apparatus for manufacturing a flattened cylindrical film consisting of layers of thermoplastic resin stretched crosswisely

Claim 1

IN AN APPARATUS FOR PRODUCING LAMINATE TUBING FROM AN OUTER, INTERMEDIATE, AND AN INNER CYLINDERICAL FILM OF PLASTIC MATERIAL EXTRUDED CONCENTRICALLY AND SPACED FROM EACH OTHER, IN WHICH THE MATERIAL OF SAID INTERMEDIATE FILM HAS A LOWER MELTING POINT THAN THAT OF THE OTHER TWO FILMS, A COMBINATION COMPRISING A FIRST PAIR OF NIP ROLLS SQUEEZING SAID CYLINDRICAL FILMS THEREBETWEEN, A SECOND PAIR OF NIP ROLLS SPACED FROM SAID FIRST PAIR AND BEING ROTATED AT A HIGHER SPEED THAN THE FIRST PAI A MANDREL LOCATED WITHIN SAID INNER CYLINDRICAL FILM BETWEEN SAID FIRST AND SECOND PAIR OF NIP ROLLS, SAID MANDREL HAVING A CYLINDRICAL PORTION OF A DIAMETER LARGER THAN THAT AT WHICH SAID INNER CYLINDRICAL FILM IS EXTRUDED TO LATERALLY EXPAND SAID INNER CYLINDERICAL FILM SUBSTANTIALLY TO THE DIAMETER OF SAID OUTER CYLINDERCICAL FILM TO THEREBY ASSURE PERIPHERAL CONTRACT OF THE THREE FILMS, MEANS FOR ANCHORING SAID MANDREL AT SAID FIRST PAIR OF NIP ROLLS, HEATING MEANS IN THE REGION OF SAID MANDREL FOR HEATING SAID FILMS CLOSE TO THE MELTING POINT OF SAID INTERMEDIATE FILM SO AS TO FUSE SAID THREE FILMS TO EACH OTHER, AND COOLING MEANS DOWNSTREAM OF SAID MANDREL FOR COOLING SAID FILMS AS THEY PASS THROUGH SAID SECOND PAIR OF NIP ROLLS.