Extrusion of parisons and blow molding

Claim 1

PARISON EXTRUSION APPARATUS COMPRISING: A DIE HAVING A PASSAGE THEREIN WHICH EXTENDS FROM AN INLET ADAPTED TO RECEIVE A THERMOPLASTIC MATERIAL TO AN OUTLET THROUGH WHICH THERMOPLASTIC MATERIAL IS EXTRUDED; A MANDREL POSITIONED FOR MOVEMENT SAID PASSAGE, SAID MANDREL AND SAID DIE BEING OF SUCH CONFIGURATION RELATIVE TO ONE ANOTHER THAT MOVEMENT OF SAID MANDREL THROUGH SAID PASSAGE TOWARD SAID OUTLET CHANGES THE SIZE OF THE OPENING BETWEEN SAID MANDREL AND SAID OUTLET, A PORTION OF SAID MANDREL WITHIN SAID PASSAGE HAVING AN INCREASING CROSS-SECTIONAL AREA IN A DIRECTION EXTENDING TOWARD SAID OUTLET TO THAT THE FLOW OF THERMOPLASTIC MATERIAL FROM SAID INLET TO SAID OUTLET TENDS TO MOVE SAID MANDEL TOWARD SAID OUTLET; MEANS CONNECTED TO SAID MANDREL TO EXERT A RETARDING FORCE TENDING TO RESIST MOVEMENT OF SAID MANDREL TOWARD SAID OUTLET RESPONSIVE TO THE FLOW OF THERMOPLASTIC MATERIAL THROUGH SAID PASSAGE TOWARD SAID OUTLET; MEANS FORMING A CHAMBER, A PISTION POSITIONED FOR MOVEMENT IN SAID CHAMBER, SAID PISTON ENGAGING THE WALLS OF SAID CHAMBER TO DIVIDE THE CHAMBER INTO FIRST AND SECOND REGIONS; MEANS CONNECTING SAID PISTON TO SAID MANDREL SO THAT MOVEMENT OF SAID MANDREL THROUGH SAID PASSAGE MOVES SAID PISTON THROUGH SAID CHAMBER; A SOURCE OF HYDRAULIC FLUID; AND FIRST AND SECOND CONDUIT MEANS CONNECTING SAID SOURCE SIMULTANEOUSLY TO SAID FIRST AND SECOND REGIONS, RESPECTIVELY, WHEREBY THE RELATIVE SIZES OF THE PASSAGES THROUGH SAID CONDUIT MEANS INFLUENCE THE FORCE EXERTED ON SAID PISTON TENDING TO RESTRICT MOVEMENT THEREOF.