Injection molding flow control apparatus and method

An injection molding system for controlling the rate of flow of a fluid mold material from an injection molding machine to a cavity of a mold, the system comprising:

• a manifold receiving the injected fluid mold material, the manifold having a delivery channel that delivers the fluid mold material to a gate to the mold cavity;
• an actuator interconnected to a valve pin having a tip end, the actuator moving the valve pin upstream along a path of travel between a downstream gate closed position and one or more intermediate upstream gate open positions, the downstream gate closed position being a position wherein the tip end of the valve pin obstructs the gate to prevent fluid material from flowing into the mold cavity, the one or more intermediate upstream gate open positions being predetermined positions between the downstream gate closed position and an end of stroke position upstream of the intermediate upstream gate open position at which the fluid mold material flows at a selected maximum rate through the gate, wherein the gate is partially open when the valve pin is in the one or more intermediate upstream gate open positions;
• a position sensor that senses and generates signals indicative of position of the valve pin,
• a controller interconnected to the actuator and to the position sensor, the controller receiving the signals indicative of position of the valve pin and controlling movement of the actuator at least in part according to instructions that utilize the signals indicative of position of the valve pin to instruct the actuator to drive the valve pin upstream at one or more selected intermediate velocities over the course of a selected portion of the travel of the valve pin between the downstream gate closed position and the end of stroke position,
• the valve pin being drivable at a selected maximum upstream velocity, the one or more selected intermediate velocities being less than the selected maximum velocity,
• a user interface that receives information from the controller indicative of one or more pin positions in real time and displays the one or more pin positions and one or more flow rate indicative parameters by which a user of the system can track the one or more pin positions and flow rate indicative parameters in real time during the injection cycle.

A method of performing an injection molding cycle in an injection molding apparatus comprising:

• an injection molding machine and a manifold that receives an injected mold material from the injection molding machine, the manifold having a delivery channel that delivers the mold material under an injection pressure to a first gate of a mold cavity, an actuator interconnected to a valve pin driving the valve pin from a first position where the tip end of the valve pin obstructs the gate to prevent the injection fluid material from flowing into the cavity, the actuator further driving the valve pin upstream to a second position upstream of the gate where the mold material flows at a maximum rate through the gate and upstream from the start position through one or more intermediate positions between the first position and the second position wherein the tip end of the valve pin restricts flow of the injection fluid to one or more rates less than the maximum rate,
• a drive system for controllably driving the actuator and the valve pin upstream at one or more selected intermediate velocities and at one or more high velocities that are higher than the intermediate velocities,
• the method comprising:
• beginning an injection cycle with the tip end of the valve pin in the first position,
• sensing the position of the valve pin,
• adjusting the drive system to drive the actuator at the one or more intermediate velocities upstream to and through one or more of the intermediate positions at the one or more selected intermediate velocities in response to sensing of the position of the valve pin in the one or more of the intermediate positions.