Injection-molding machine for plastics

Claim 1

IN A PLASTIC INJECTION-MOLDING MAC HINE, MOLD-SUPPORT MEANS, PLASTICIZING MEANS INCLUDING AN ELONGATED TUBULAR CHAMBER WITH MATERIAL FEED MEANS AT ONE END AND A MOLD-INJECTION NOZZLE AT THE OTHER END, A PLASTICIZING SCREW RECIPROCABLY SUPPORTED WITHIN SAID CHAMBER AND HAVING THREADS OVERLAPPING SAID MATERIAL FEED MEANS WHEN IN RETRACTRED POSITION, ROTARY-DRIVE MEANS FOR ROTATING SAID SCREW WITHIN SAID CHAMBER TO PLASTICIZE MATERIAL INTRODUCED AT SAID MATERIAL FEED MEANS, SAID DRIVE MEANS DRIVING SAID SCREW AFTER COMPLETION OF A MOLD INJECTION, WHEREBY SAID SCREW AFTER COMPLETION OF A MOLD INJECTION, WHEREBY SAID SCREW IS DISPLACED IN A RETRACTING DIRECTION AS PLASTICIZED MATERIAL IS ACCUMULATED IN THE FORWARD END OF SAID CHAMBER, HYDRAULIC-FEED MEANS, INCLUDING A PISTON AND CYLINDER, FOR LONGITUDINALLY ADVANCING SAID SCREW FROM ITS RETRACTED POSITION TO A FORWARD POSITION ADJACENT SAID NOZZLE, SAID HYDRALIC FEED MEANS INCLUDING BLEED MEANS RESTRICTING EXPULSION OF FLUID AND THUS CONTINUOUSLY AXIALLY FORWRDLY LOADING SAID SCREW AS LONG AS SAID SCREW IS RETRACTING, SAID HYDRAULIC-FEED MEANS INCLUDING VARIBLE LOADING CONTROL MEANS, AND SELECTIVELY VARIABLE MEANS LONGITUDINALLY CONTINUOUSLY RESPONSIVE TO REARWARD DISPLACEMENT OF SAID SCREW AND CONTINUOUSLY CONNECTED IN LOAD-VARYING CONTROL RELATION WITH SAID HYDRAULIC-FEED MEANS, WHEREBY QUALITY OF ACCUMULATED MELT MAY BE BETTER CONTROLLED AS THE EFFECTIVE LENGTH OF PLASTICIZING SCREW CHANGES DURING MELT ACCUMULATION.