Injection molding machine

Claim 1

AN INJECTION MOLDING MACHINE COMPRISING, IN COMBINATION, AN ELONGATED, HOLLOW CYLINDER, OF SUBSTANTIALLY CONSTANT INTERNAL DIAMETER THROUGHOUT ITS LENGTH, HAVING AN INJECTION CHAMBER AND INJECTION NOZZLE DEFINED AT ONE END THEREOF AND A FEED HOPPER DEFINED AT AN OPPOSITE END THEREOF FOR FEEDING MATERIAL INTO SAID CYLINDER; A SINGLE ELONGATED WORM SCREW, INCLUDING A LONGITUDINAL SHAFT AND A HELICAL THREAD ON SAID SHAFT, MOUNTED INSIDE SAID CYLINDER FOR RELATIVE ROTATION AND AXIAL RECIPROCATION THEREIN, THE ROTATION OF SAID WORM SCREW PLASTICIZING THE MATERIAL AND ADVANCING IT TOWARD AND INTO SAID INJECTION CHAMBER, ONE END OF SAID WORM SCREW HAVING AN INJECTION HEAD DEFINED THEREIN WHICH IS SITUATED WITHIN SAID INJECTION CHAMBER REARWARDLY OF SAID INJECTION NOZZLE, AND IS MOVED TOWARD SAID INJECTION NOZZLE BY AXIAL RECIPROCATION OF SAID WORM SCREW; MEANS ASSOCIATED WITH SAID INJECTION CHAMBER AND SAID INJECTION HEAD TO PREVENT MATERIAL FROM BEING MOVED FROM SAID INJECTION CHAMBER INTO SAID CYLINDER; THE PARAMETERS OF SAID WORM SCREW BEING SUCH AS TO DEFINE, WITH SAID CYLINDER, A PAIR OF AXIALLY SPACED COMPRESSION ZONES, EACH DECREASING IN VOLUME TOWARD SAID INJECTION CHAMBER, SEPARATED BY AN AXIALLY ELONGATED, SUBSTANTIALLY CONSTANT VOLUME, VACUUM ZONE HAVING AN AXIAL LENGTH AT LEAST EQUAL TO THE AXIAL RECEPROCATION STROKE OF SAID WORM SCREW; AND MEANS CONNECTED TO THE INTERIOR OF SAID CYLINDER AT SAID VACUUM ZONE AND MAINTAINING A VACUUM IN SAID VACUUM ZONE; SAID WORM SCREW AND SAID CYLINDER CONJOUNTLY DEFINING AN EXPANSION ZONE BETWEEN SAID VACUUM ZONE AND SAID FEED HOOPER.