Hold pressurization by confining runner systems of adjustable feed

Abstract

A system and method of cyclic injection molding a plastic material by controlling hold pressure and transferring plastic material to molding cavities of a stacked multi-parting injection molding system having desynchronized injection periods. The system includes left, left center, center, right center and right molding blocks disposed for movement with respect to each other along a common axis; and defining a left molding cavity between the left and the left center molding blocks, a left center molding cavity between the left center and the center molding blocks, a right center molding cavity between the center and the right center molding blocks, and a right molding cavity between the right center and the right molding blocks. The left center and right center molding blocks each contain a bifurcated runner system, confining means for confining injected plastic material therein, hold pressurizing means for hold pressurizing the confined injected plastic material in the bifurcated runner system and an inlet orifice, for feeding the adjacent molding cavities. The system further includes a clamping unit for moving axially the left molding block in relation to the right molding block and providing collective axial clamping force on the left, left center, right center and right molding cavities; a left locking system for maintaining the left and left center molding cavities in a closed position when the right center and right molding cavities in an open position; a right locking system for maintaining the right center and right molding cavities in a closed position when the left and left center and right molding cavities in a closed position when the left and left center molding cavities are in an open position; and an adjustable feed system encompassed by a combination of the left center and the right center molding blocks and a plasticizing system which has one or more outlet orifices.