Gas delivery nozzle for film casting apparatus

Claim 1

IN AN APPARATUS FOR CASTING OF FILMS FROM MOLTEN THERMOPLASTIC MATERIAL WHICH INCLUDES A DIE FOR EXTRUDING A SHAPED STREAM OF MOLTEN THERMOPLASTIC MATERIAL, A CHILL SURFACE FOR RECEIVING THE EXTRUDED STREAM OF MOLTEN THERMOPLASTIC MATERIAL AND COOLING THE SAME INTO A FILM, MEANS FOR MOVING THE CHILL SURFACE AT A UNIFORM PREDETERMINED RATE, MEANS FOR MAINTAINING THE CHILL SURFACE AT A SELECTED TEMPERATURE, AN IMPROVED NOZZLE FOR IMPINGING A STREAM OF GASEOUS MEDIUM AGAINST THE SHAPED STREAM OF MOLTEN THERMOPLASTIC MATERIAL WITH SUBSTANTIALLY UNIFORM PRESSURE AT LEAST ACROSS A PORTION OF THE WIDTH THEREOF, SAID NOZZLE INCLUDING AN ELONGATED MANIFOLD, A PLENUM CHAMBER EXTENDING AT LEAST COEXTENSIVELY WITH SAID MANIFOLD, WALLS DEFINING AN ELONGATED OPENING INTERCONNECTING SAID MANIFOLD AND PLENUM CHAMBER, A PAIR OF SPACED BLADES CONNECTED TO SAID PLENUM CHAMBER AND TOGETHER DEFINING AN EXIT ORIFICE, AN ELONGATED SLOT IN SAID PLENUM CHAMBER OPENING IN-BETWEEN SAID BLADES, SAID ELONGATED OPENING AND SLOT EACH BEING NARROWER THAN THE SAID PLENUM CHAMBER, PLATES EXTENDING ACROSS THE ENDS OF SAID MANIFOLD, PLENUM CHAMBER, AND BLADES, AND MEANS FOR DELIVERING GASEOUS MEDIUM INTO THE OPPOSITE ENDS OF SAID MANIFOLD THROUGH INLET OPENINGS FORMED IN SAID PLATES.