SEQUENTIAL FILL VALVE GATED INJECTION MOLDING SYSTEM

摘要

A system for injection molding of large components is disclosed that provides for the production of higher quality large molded components with a reduction in both molding cycle time and molding costs. Plasticized material communicates with a mold, having at least one single cavity, through a manifold that has at least two spaced valve gates that are independently opened and closed as directed by a controller to selectively communicate plasticized material to the mold cavity at separate locations in the mold cavity. The controller directs the valve gates to sequentially open and close during the filling phase so as to achieve the desired melt front advancement within the mold cavity. Once the mold cavity has been filled as desired, the valve gates are closed to effectively seal the manifold from the mold cavity. The plasticized material within the manifold is held in compression while the mold cavity is open, so as to prevent appreciable expansion of the material that has been found to result in molded part imperfections. Additional material may be plasticized and held in compression while the mold cavity is open, resulting in a further reduction in overall cycle time.