Patent ID: 7731489

Claim:
A coinjection molding apparatus comprising: at least one manifold having a first manifold melt channel and a second manifold melt channel; a hot runner nozzle located between the manifold and a mold gate, wherein the nozzle has melt channels communicating with the first manifold melt channel and the second manifold melt channel; a valve having a movable valve member for increasing and decreasing flow of melt in one of the melt channels of the nozzle, the valve member receiving a pressure force from the melt; and an actuator providing a control force to the valve member, wherein the valve member moves in response to a difference between the pressure force and the control force, wherein when the control force exceeds the pressure force, the valve member moves to enlarge a melt path and increase the pressure force; and when the pressure force exceeds the control force, the valve member moves to constrict the melt path and decrease the pressure force, wherein when the control force exceeds the pressure force, the valve member moves to enlarge a melt path and increase the pressure force; and when the pressure force exceeds the control force, the valve member moves to constrict the melt path and decrease the pressure force.