Injection molding apparatus with plural reciprocating screws

Claim 1

AN INJECTION MOLDING MACHINE, COMPRISING, IN COMBINATION, A PLURALITY OF INJECTION CYLINDERS, EACH HAVING A FRONT END AND FORMING AT SAID FRONT END A PRESSURE CHAMBER; NOZZLE MEANS CONNECTED TO SAID FRONT ENDS OF SAID INJECTION CYLINDERS AND COMMUNICATING WITH SAID PRESSURE CHAMBERS; A PLURALITY OF RAM MEANS RESPECTIVELY SUPPORTED IN SAID INJECTION CYLINDERS FOR ROTATIONAL MOVEMENT AND FOR MOVEMENT IN AXIAL DIRECTION BETWEEN A FORWARD INJECTION STROKE FOR EJECTING MATERIAL FROM THE RESPECTIVE PRESSURE CHAMBER THROUGH SAID NOZZLE MEANS AND RETURN STROKE, EACH OF SAID RAM MEANS INCLUDING A PLUNGER FORMING FRONT END PORTION, A HELICALLY GROOVED PLASTICIZING AND FEEDSCREW FORMING MIDDLE PORTION, AND A REAR PORTION; SUPPLY MEANS INDIVIDUALLY COMMUNICATING WITH EACH OF SAID CYLINDERS IN THE REGION OF SAID MIDDLE PORTION OF THE RAM MEANS THEREIN FOR SUPPLYING PLASTIC MATERIAL INTO SAID CYLINDERS; DRIVE MEANS CONNECTED TO SAID PLURALITY OF RAM MEANS FOR SIMULTANEOUSLY ROTATING THE SAME SO THAT PLASTIC MATERIAL SUPPLIED BY THE SUPPLY MEANS IS PROGRESSIVELY FED UNDER PRESSURE WHILE BEING PLASTICIZED INTO SAID PRESSURE CHAMBERS; AND FLUID ACTUATED MEANS CONSTRUCTED AND CONNECTRED TO SAID REAR PORTIONS OF ALL OF SAID RAM MEANS FOR SIMULTANEOUSLY MOVING THE SAME THROUGH EQUAL DISTANCES ALONG SAID FORWARD INJECTION STROKE FOR EJECTING MATERIAL FROM SAID PRESSURE CHAMBERS THROUGH SAID NOZZLE MEANS AND FOR INDIVIDUALLY CONTROLLING THE RETURN STROKE OF EACH RAM MEANS UNDER THE INFLUENCE OF THE PRESSURE BUILT UP IN THE RESPECTIVE PRESSURE CHAMBER DURING CONTINUOUS ROTATION OF THE RESPECTIVE RAM MEANS.