Injection-molding machine

Claim 1

IN AN INJECTION-MOLDING MACHINE, IN COMBINATION, A MOLD PROVIDED WITH A SUBSTANTIALLY STATIONARY FIRST PORTION AND A MOVABLE SECOND PORTION DEFINING AT LEAST ONE CAVITY BETWEEN THEM, SAID FIRST PORTION BEING PROVIDED WITH AT LEAST ONE INJECTION PASSAGE TERMINATING AT SAID CAVITY; A PRECOMPRESSION CHAMBER COMMUNICATING WITH SAID PASSAGE; INLET MEANS FORMING A FEED CHANNEL TERMINATING IN A PERMANENTLY OPEN INLET TO SAID CHAMBER, SAID INLET MEANS INCLUDING SUPPLY MEANS FOR ADMITTING A MOLDABLE PLASTIC MATERIAL TO SAID FEED CHANNEL AT A LOCATION REMOTE FROM SAID CHAMBER, SCREW MEANS IN SAID CHANNEL EXTENDING FROM SAID SUPPLY MEANS TO THE VICINITY OF SAID CHAMBER, AND A POWER SOURCE COUPLED WITH SAID SCREW MEANS FOR CONTINUOUSLY DELIVERING SAID MATERIAL UNDER PRESSURE TO SAID CHAMBER BY ROTATING SAID SCREW MEANS; A PISTON RECIPROCABLE IN SAID CHAMBER AHEAD OF SAID INLET FOR PERIODICALLY EXPELLING SAID MATERIAL UNDER PRESSURE INTO SAID PASSAGE IN A SUCCESSION OF OPERATING CYCLES EACH INCLUDING A FORWARD STROKE AND A RETURN STROKE OF SAID PISTON; VALVE MEANS AT THE JUNCTION OF SAID PASSAGE WITH SAID CAVITY FOR BLOCKING SAID PASSAGE DURING AT LEAST PART OF EACH FORWARD STROKE; FIRST DRIVE MEAND INCLUDING A MOTOR-DRIVEN CRANK FOR CONTINUOUSLY RECIPROCATING SAID PISTON; INTERMITTENTLY OPERABLE SECOND DRIVE MEANS FOR ALTERNATELY DISPLACING SAID SECOND PORTION INTO CONTACT WITH AND AWAY FROM SAID FIRST PORTION DURING A FORWARD STROKE AND A RETURN STROKE, RESPECTIVELY, OF SAID PISTON WHEREBY SAID MOLD IS ALTERNATELY CLOSED FOR A MOLDING OPERATION AND OPENED FOR THE EJECTION OF A MOLDED ARTICLE THEREFROM; FIRST SWITCH MEANS CONTROLLED BY SAID SECOND DRIVE MEANS FOR ARRESTING SAID SECOND PORTION IN THE CLOSED POSITION OF SAID MOLD; MECHANISM CONTROLLED BY ONE OF SAID DRIVE MEANS FOR TEMPORARILY OPENING SAID VALVE MEANS IN SAID CLOSED POSITION; AND SECOND SWITCH MEANS CONTROLLED BY SAID CRANK FOR RESTARTING SAID SECOND DRIVE MEANS UPON ADMISSION OF SAID PLASTIC MATERIAL INTO SAID CAVITY BY WAY OF SAID PASSAGE.