SOLVENT FLUSH REACTION INJECTION MOLDING MIXHEAD

摘要

A solvent flush reaction injection molding mixhead has a mixing chamber with a solvent inlet port in one end and a chemical outlet port in an opposite end. A pair of hydraulically operated chemical injectors are connected to the mixing chamber between the solvent inlet port and chemical outlet port and at directly opposite locations and inject liquid reaction molding chemicals at high pressure through injector ports into the mixing chamber. The injected chemicals impinge at high velocity on entering the mixing chamber resulting in their thorough mixing and are delivered through the chemical outlet port to a spray wand on the mixhead for spraying onto a mold surface or an object requiring a foam coating. A flush valve is connected by a piston rod to a hydraulically actuated piston and is moveable thereby from a closed position closing the solvent inlet port against the force of the chemicals injected into the mixing chamber to an open position where the flush valve uncovers this port. A liquid solvent under a high pressure but less than that of the injected chemicals is supplied to a solvent feed passage that extends through the flush valve piston rod and piston into the flush valve where it communicates with solvent feed ports in the flush valve that are blocked when the flush valve is in its closed position. In its open position and following a dispensing of mixed chemicals, the solvent feed ports in the flush valve are opened to the turbulator ports which then deliver turbulent solvent flow under high pressure to clean and flush any remaining mixed chemicals from the flush valve, the mixing chamber including the chemical injector ports, and the spray wand.