Method for making plastic articles

Claim 1

IN A METHOD OF MAKING AN ARTICLE FROM THERMOPLASTIC MATERIAL BY A COMBINED INJECTION MOLDING, EXTRUSION AND BLOWING TECHNIQUE, THE STEPS OF (1) PLASTICIZING THERMOPLASTIC MATERIAL IN A SCREW TYPE PLASTICIZER HAVING A SCREW ROTATABLE AND AXIALLY DISPLACEABLE IN A TUBULAR BARREL FREELY COMMUNICATING WITH AN OUTLET ORIFICE TO PROVIDE A BODY OF PLASTICIZED MATERIAL COMMUNICATING THROUGH A PASSAGE WITH THE ORIFICE, SAID BODY BEING MAINTAINED AT A FIRST PRESSURE BY ROTATION OF SAID SCREW, (2) INTERPOSING A RESTRICTION IN SAID PASSAGE WITHOUT BLOCKING SAID PASSAGE, SAID RESTRICTION BEING SMALL ENOUGH THAT AXIAL MOVEMENT OF SAID SCREW IS REQUIRED IN ORDER TO FORCE PLASTICIZED MATERIAL THROUGH SAID RESTRICTION, THE FIRST PRESSURE GENERATED BY ROTATION OF SAID SCREW BEING INSUFFICIENT TO FORCE THE PLASTICIZED MATERIAL THROUGH SAID RESTRICTION, (3) ADVANCING SAID SCREW AXIALLY IN SAID BARREL TO SUBJECT SAID BODY OF PLASTICIZED MATERIAL TO A SECOND PRESSURE GREATER THAN SAID FIRST PRESSURE AND SUFFICIENT TO FORCE PLASTICIZED MATERIAL FROM SAID BODY THROUGH SAID RESTRICTION AND SAID ORIFICE INTO AN INJECTION MOLD POSITIONED AT SAID ORIFICE, (4) SIMULTANEOUSLY MOVING THE MOLD FROM THE ORIFICE AND FURTHER ADVANCING THE SCREW TO EXTRUDE A TUBE INTEGRAL WITH THE MATERIAL IN THE MOLD, (5) CLOSING A BLOW MOLD ON SAID TUBE TO PINCH THE TUBE SHUT EXTERIORLY OF SAID ORIFICE, (6) INTRODUCING AIR INTO THE PINCHED TUBE TO INFLATE THE TUBE INTERIORLY OF THE BLOW MOLD, (7) DURING THE PERFORMANCE OF STEPS 5 AND 6 ABOVE RETRACTING THE SCREW IN SAID BARREL AND ROTATING THE SCREW TO AGAIN ACCUMULATE A BODY OF PLASTICIZED MATERIAL COMMUNICATING WITH SAID PASSAGE, (8) OPENING THE BLOW MOLD AND REMOVING THE BLOW ARTICLE THEREFROM, AND (9) PERFORMING STEP 3 ABOVE TO REINSTITUTE A FORMING CYCLE.