Apparatus for producing thermoplastic tubing

Claim 1

AN APPARATUS FOR PREPARING BLOWN PLASTIC SEAMLESS TUBING, COMPRISING MEANS FOR EXTRUDING A MOLTEN THEREMOPLASTIC THROUGH AN ANNULAR ORIFICE IN THE FORM OF TUBING, MEANS TO WITHDRAW SAID TUBING FROM SAID DIE, MEANS TO INFLATE SAID TUBING, AND MEANS FOR PROVIDING A SUBSTANTIALLY UNIFORM ANNULAR FLOW OF GAS COVERGING ON THE SURFACE OF SAID TUBING AS IT EMERGES FROM SAID DIE, THE LATTER MEAS COMPRISING AN ANNULAR STATIONARY BEARING MADE OF PLASTIC AND HAVING A FIRST PLURALITY OF OPENINGS THEREIN, STATIONARY MEANS TO SUPPLY SAID BEARING, STATIONARY PLENUM MEANS COMMUNICATING WITH SAID FIRST PLURALITY OF OPENINGS, MEANS TO SUPPLY SAID GAS TO SAID PLENUM MEANS, ROTATABLE ANNULAR HOLLOW MEANS POSITIONED ON SAID BEARING AND DEFINING WITH SAID BEARING AN ANNULAR CHANNEL COMMUNICATING WITH SAID FIRST PLURALITY OF OPENINGS, SAID ROTATABLE HOLLOW ANNULAR MEANS HAVING A SECOND PLURALITY OF OPENINGS COMMUNICATING WITH SAID ANNULAR CHANNEL, SAID ROTATABLE HOLLOW ANNULAR MEANS ALSO PROVIDED WITH AN ANNULAR OPENING ADJACENT ITS INNER PERIPHERY FOR DISCHARGE OF SAID CONVERGING FLOW OF GAS, AND MEANS TO ROTATE SAID ROTATABLE ANNULAR MEANS.