Patent ID: 7658607

Claim:
A crossover nozzle system for transferring molten plastic from a feeder manifold to a main manifold of the molding chambers of the stack molds of an injection molding machine, the system comprising: a primary sprue bar having an aperture in fluid communication with the feeder manifold; a front floating sprue insert having a central aperture and urging means housed in the central aperture; a transfer chamber formed between the front floating sprue insert and the primary sprue bar, said transfer chamber in fluid communication with the aperture in the primary sprue bar and with one or more radial apertures in the front floating sprue insert; a shut-off valve having a first end and a second end, said first end of the shut off valve being slidably housed in the central aperture of the front floating sprue and being biased by the urging means; and a primary sprue shut-off insert having an aperture in fluid communication with the one or more radial apertures in the front floating sprue insert, wherein: said shut-off valve having a non-uniform diameter in contact with molten plastic, said non-uniform diameter being configured to create a bias force based on a pressure of molten plastic, said second end of the shut-off valve being configured to disengage from an opening on the front floating sprue insert when the pressure of molten plastic overcomes the force of said biasing means, thus opening flow of molten plastics to the molds, and said second end of the shut-off valve being configured to engage with an opening on the front floating sprue insert when the force of said biasing means overcomes the pressure of molten plastic, thus closing flow of molten plastics to the molds.