FLOW CONTROL APPARATUS AND METHOD

A method of performing an injection molding cycle in an injection molding apparatus comprising a manifold that receives an injection fluid， the manifold distributing injection fluid to a fluid delivery channel that delivers the injection fluid under an injection pressure to a gate of a mold cavity and a valve pin having an axis and a tip end， the valve pin being slidably mounted for movement along the axis within the fluid delivery channel， the method comprising: drivably interconnecting the valve pin to an actuator in an arrangement wherein the actuator drives the valve pin upstream and downstream along the axis and drives the tip end of the valve pin upstream and downstream between a first closed position where the tip end of the valve pin obstructs the gate to prevent the injection fluid from flowing into the cavity， a full open position where the injection fluid material flows freely without restriction from the tip end of the pin through the gate， and an intermediate position between the first position and the full open position wherein the tip end of the valve pin restricts flow of the injection fluid along at least a portion of the length of the drive path extending between the first closed position and the intermediate position， and， controllably operating the actuator to drive the valve pin to be disposed in a selected intermediate position for a selected period of time during the course of an injection cycle where the tip end of the valve pin restricts flow of injection fluid through the gate to the mold cavity.