Patent ID: 9636858
Date: 2017-05-02
CPC Classifications: B29C,B29K,G05B,G05D

Claim:
1. A method of performing an injection molding cycle in an injection molding apparatus comprising: a manifold that receives an injection fluid mold material, the manifold having a delivery channel that delivers the injection fluid mold material under an injection pressure to a first gate of a mold cavity, an actuator drivably interconnected to a valve pin having a tip end drivable along a drive path that extends between 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, a second position upstream of the first 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 position and the second position, and a third position upstream of the second position where the injection fluid material flows freely without restriction from the tip end of the pin through the first gate, the actuator being driven by a valve system that is controllably adjustable between a start position, one or more intermediate drive rate positions and a high drive rate position, the actuator being driven upstream at one or more corresponding intermediate rates of travel when the valve system is in the one or more intermediate drive rate positions and at a higher rate of travel than the one or more intermediate rates of travel when the valve system is in the high drive rate position, the method comprising: selecting the length of travel between the first position and the second position, beginning an injection cycle with the tip end of the valve pin in the first position and the valve system in the start position, adjusting the valve system to operate at the one or more selected intermediate drive rate positions to drive the tip end of the valve pin continuously upstream from the first position to the second position, sensing the position of the valve pin to determine when the tip end of the valve pin has reached the second position, adjusting the valve system to operate at the high drive rate position to drive the tip end of the valve pin continuously upstream at the higher rate of travel when the tip end of the valve pin has been determined in the step of sensing to have reached the second position.