Apparatus for producing injection molded plastic articles

Claim 1

AN INJECTION MOLDING APPARATUS COMPRISING, IN COMBINATION, SUPPORT MEANS; AT LEAST ONE MOLD MOUNTED ON SAID SUPPORT MEANS AND HAVING AN INLET PASSAGE; AND INJECTION MEANS INCLUDING MOVING MEANS HAVING A STATIONARY MEMBER FIXEDLY CARRIED BY SAID SUPPORT MEANS AND A MOVABLE MEMBER GUIDED BY SAID STATIONARY MEMBER FOR MOVEMENT TOWARD AND AWAY FROM SAID MOLD, A PISTON CARRIED BY SAID MOVABLE MEMBER FOR MOVEMENT THEREWITH TOWARD AND AWAY FROM SAID MOLD, A CYLINDER SURROUNDING SAID PISTON AND CARRIED THEREBY MOVABLE THEREWITH IN AXIAL DIRECTION BETWEEN AN ADVANCED POSITION AND A RETRACTED POSITION, SAID CYLINDER DEFINING BETWEEN ONE END THEREOF FACING SAID MOLD AND ONE SIDE OF SAID PISTON A VARIABLE VOLUME CHAMBER AND SAID PISTON BEING MOVABLE RELATIVE TO SAID CYLINDER SO THAT THE VOLUME OF SAID CHAMBER DECREASES WHEN SAID PISTON MOVES RELATIVE TO SAID CYLINDER TOWARD SAID ONE END THEREOF AND INCREASES WHEN SAID PISTON MOVES TOWARD THE OTHER END OF SAID CYLINDER, STOP MEANS ENGAGING SAID OTHER END OF SAID CYLINDER AT THE RETRACTED POSITION THEREOF, NOZZLE MEANS CARRIED BY SAID ONE END OF SAID CYLINDER FORMED WITH A BORE THERETHROUGH COMMUNICATING WITH SAID CHAMBER AND HAVING AN OUTLET END AXIALLY ALIGNED WITH SAID INLET PASSAGE OF SAID MOLD, SAID NOZZLE MEANS ENGAGING SAID MOLD WHEN SAID CYLINDER IS IN SAID ADVANCED POSITION SO THAT SAID OUTLET END COMMUNICATES WITH SAID INLET PASSAGE, A SOURCE OF PLASTIC MATERIAL, PASSAGE MEANS PROVIDING COMMUNICATION BETWEEN SAID SOURCE OF PLASTIC MATERIAL AND A PORTION OF SAID BORE, FIRST ONE-WAY VALVE MEANS IN SAID PASSAGE MEANS PERMITTING FLOW OF PLASTIC MATERIAL FROM SAID SOURCE THROUGH SAID PASSAGE MEANS SO THAT PLASTIC MATERIAL WILL BE SUCKED INTO SAID CHAMBER WHEN SAID PISTON MOVES TOWARD SAID OTHER END OF SAID CYLINDER WHILE FLOW IN OPPOSITE DIRECTION THROUGH SAID PASSAGE MEANS IS PREVENTED DURING MOVEMENT OF SAID PISTON IN OPPOSITE DIRECTION, AND SECOND ONE-WAY VALVE MEANS IN SAID BORE DOWNSTREAM OF SAID PORTION MOVABLE BETWEEN A CLOSED POSITION AND AN OPEN POSITION FOR PERMITTING IN THE LATTER FLOW OF PLASTIC MATERIAL FROM SAID CHAMBER TO SAID OUTLET END OF SAID BORE AND INCLUDING ADJUSTABLE RESILIENT MEANS TENDING TO KEEP SAID SECOND ONE-WAY VALVE MEANS IN SAID CLOSED POSITION UNTIL PRESSURE ON THE PLASTIC MATERIAL IN SAID CHAMBER REACHES A PREDETERMINED PRESSURE, WHEREBY DURING MOVEMENT OF SAID MOVABLE MEMBER AWAY FROM SAID MOLD SAID PISTON AND SAID CYLINDER WILL FIRST MOVE TOGETHER TO THE RETRACTED POSITION OF THE LATTER UNTIL SAID CYLINDER ENGAGES SAID STOP MEANS AFTER WHICH SAID PISTON WILL MOVE RELATIVE TO SAID CYLINDER TOWARD THE OTHER END THEREOF SO THAT PLASTIC MATERIAL IS SUCKED INTO SAID CHAMBER WHILE DURING MOVEMENT OF SAID MOVABLE MEMBER TOWARD SAID MOLD SAID PISTON WILL MOVE WITH SAID CYLINDER TO SAID ADVANCED POSITION OF THE LATTER WHILE OUTFLOW OF PLASTIC MATERIAL FROM SAID CHAMBER THROUGH SAID BORE IS PREVENTED BY SAID SECOND ONEWAY VALVE MEANS KEPT IN CLOSED POSITION BY SAID ADJUSTABLE RESILIENT MEANS THEREOF UNTIL SAID NOZZLE MEANS ENGAGES SAID MOLD PREVENTING THEREBY FURTHER MOVEMENT OF SAID CYLINDER TOGETHER WITH SAID PISTON SO THAT THE LATTER MOVES RELATIVE THERETO TOWARD SAID ONE END THEREOF INCREASING THEREBY THE PRESSURE ON THE PLASTIC MATERIAL BEYOND SAID PREDETERMINED PRESSURE AND MOVING SAID SECOND ONE-WAY VALVE MEANS TO THE OPEN POSITION THEREOF SO THAT PLASTIC MATERIAL WILL BE INJECTED FROM SAID CHAMBER INTO SAID MOLD.