Injection molding 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 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 valve system comprising a source of valve drive fluid that pumps the drive fluid at a maximum drive rate, a first valve interconnected to the source that is selectively adjustable to adjust rate of flow of the drive fluid from the source to a selected less than maximum drive rate and a second valve controllably movable between a first position where the second valve is directly interconnected to the source and a second position where the second valve is interconnected to the first valve, the second valve enabling maximum flow of drive fluid received from either the source or the first valve;
• the method comprising:
• selecting a predetermined amount of initial withdrawal time;
• 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,
• adjusting the second valve to move from the first to the second position to cause 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 predetermined amount of initial withdrawal time has elapsed.

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 valve system comprising a source of valve drive fluid that pumps the drive fluid at a maximum drive rate, a first valve interconnected to the source that is selectively adjustable to adjust rate of flow of the drive fluid from the source to a selected less than maximum drive rate and a second valve controllably movable between a first position where the second valve is directly interconnected to the source and a second position where the second valve is interconnected to the first valve, the second valve enabling maximum flow of drive fluid received from either the source or the first valve;
• the method comprising:
• selecting the length of travel between the first position and the second position of the actuator,
• 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 second valve to move from the first to the second position to cause 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.

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

• a manifold receiving the injected fluid mold material, the manifold having a delivery channel that delivers the injected fluid material to a first gate leading to the mold cavity;
• an actuator 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 first 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 through the first gate 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 through the first gate without restriction from the tip end of the pin,
• the actuator and the valve pin being translationally driven at a controllable rate of travel 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 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 valve system comprising a source of valve drive fluid that pumps the drive fluid at a maximum drive rate, a first valve interconnected to the source that is selectively adjustable to adjust rate of flow of the drive fluid from the source to a selected less than maximum drive rate and a second valve controllably movable between a first position where the second valve is directly interconnected to the source and a second position where the second valve is interconnected to the first valve, the second valve enabling maximum flow of drive fluid received from either the source or the first valve;
• a position sensor and a controller,
• the position sensor sensing the position of the valve pin and sending a signal indicative of the position of the pin to the controller;
• the controller instructing the valve system to drive the actuator and the valve pin continuously upstream from the start position to the second position to the third position;
• the controller including instructions that instruct the second valve to move from the second position to the first position on receipt by the controller of a signal from the position sensor that is indicative of the valve pin having reached the second position.

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

• a manifold receiving the injected fluid mold material, the manifold having a delivery channel that delivers the injected fluid material to a first gate leading to the mold cavity;
• an actuator 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 first 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 through the first gate 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 through the first gate without restriction from the tip end of the pin,
• the actuator and the valve pin being translationally driven at a controllable rate of travel 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 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 valve system comprising a source of valve drive fluid that pumps the drive fluid at a maximum drive rate, a first valve interconnected to the source that is selectively adjustable to adjust rate of flow of the drive fluid from the source to a selected less than maximum drive rate and a second valve controllably movable between a first position where the second valve is directly interconnected to the source and a second position where the second valve is interconnected to the first valve, the second valve enabling maximum flow of drive fluid received from either the source or the first valve;
• a controller including a timer,
• the timer including a memory containing a preselected period of time over which the first valve is interconnected to the source and the second valve is in the second position;
• the controller instructing the valve system to drive the actuator and the valve pin continuously upstream from the start position to the second position to the third position;
• the controller including instructions that instruct the second valve to move from the second position to the first position on receipt by the controller of a signal from the controller that the timer has determined that the preselected period of time has elapsed since the start of the injection cycle.