Patent attributes
An injection molding apparatus for injecting resin into a mold comprises an injection cylinder in fluid communication with the mold, wherein movement of a piston relative to the cylinder injects a selected quantity of resin into the mold. A plasticizing unit includes a flighted screw rotating in a heated containment barrel for plasticizing resin. The plasticizing unit is in fluid communication with the injection cylinder for supplying the injection cylinder with plasticized resin. A valve is provided for selectively placing the injection cylinder in fluid communication with the mold and placing the plasticizing unit in fluid communication with the injection cylinder, wherein the valve exerts pressure on resin in the mold independently of the injection cylinder or plasticizing unit. The valve is actuated by relative movement between the mold and one of the injection cylinder and the plasticizing unit.
