Controlled valve pin movement based on cavity sensor feedback

Abstract

Apparatus and method for performing an injection molding cycle in an injection molding apparatus where the apparatus comprises: a manifold, an actuator associated with a respective gate, each gate having a downstream sensor generating a response signal upon sensing a selected condition of the injection fluid material, each gate having an upstream sensor generating a response signal upon sensing the selected condition of the injection fluid material, the upstream and downstream sensors sending response signals to a controller on performance of each successive injection cycle by the apparatus, the controller comparing a standard amount of elapsed time with a calculated amount of elapsed time and adjusting the velocity or position of each of the actuators such that the amount of time elapsed approaches or matches the standard amount of elapsed time.

What is claimed is: 
     
         1 . A method of performing an injection molding cycle in an injection molding apparatus comprised of:
 a manifold that receives an injection fluid material, the manifold having or communicating with a delivery channel that delivers the injection fluid mold material under an injection pressure to two or more gates each leading to an associated mold cavity,   an actuator associated with each respective gate,   each actuator being drivably interconnected to a valve pin drivable upstream and downstream along a path of travel having a selected stroke length that extends between a gate closed position, a selected maximum flow position at which the injection fluid material flows at a maximum rate through the gate into the cavity and one or more selectable intermediate positions between the first position and the maximum flow position,   each actuator being controllably drivable to position an interconnected valve pin at the first, one or more selectable intermediate and maximum flow positions over the course of an injection cycle,   a downstream sensor that senses a selected physical condition of the injection fluid material at a position within a mold cavity that is downstream of an associated gate, the downstream sensor generating a signal corresponding to the sensed values,   the method comprising the steps of:   selecting and recording as a standard for a selected one of the gates, the amount of time elapsed between movement of the valve pin associated with the selected one of the gates out of the gate closed position and the time at which the downstream sensor first senses the selected condition of the injection fluid material flowing into the associated mold cavity,   performing a subsequent injection cycle for each of the other gates and sensing the selected physical condition of the injection fluid material at the downstream position with the downstream sensor associated with each of the other gates, and,   recording the amount of time elapsed between movement of the valve pin associated with each of the other gates out of the gate closed position and the time at which the downstream sensor first senses the selected condition of the injection fluid material flowing into the associated cavities of each of the other gates,   comparing the recorded amounts of time elapsed associated with each of the other gates with the standard amount of time elapsed that is associated with the selected one of the gates,   adjusting position or velocity of the actuators or valve pins associated with each of the other gates during further subsequent injection cycles such that the amount of time elapsed between movement of the valve pins associated with each of the other gates of their gate closed position and the time at which the downstream sensor first senses the selected condition of the injection fluid material approaches or matches the selected standard amount of elapsed time,   wherein the step of recording the amount of time elapsed between movement of the valve pin and the time at which the downstream sensor first senses the selected condition comprises:   detecting movement of the valve pin by sensing position of the valve pin with a position sensor,   and wherein the step of adjusting position or velocity of the actuator or valve pin so that the amount of time elapsed approaches or matches the selected standard amount of elapsed time comprises:   adjusting the position of a distal tip end of the valve pin having a configuration that interacts with an interior surface of a respective gate area to provide a reduced rate of material flow along the path of travel in the one or more selectable intermediate positions.   
     
     
         2 . The method of  claim 1  wherein the steps of performing and adjusting are carried out automatically by an algorithm executed by a controller interconnected to and controllably driving or adjusting the drive of the actuators. 
     
     
         3 . The method of  claim 1  wherein the step of selecting and recording comprises recording and establishing a standard profile of position of the actuator or valve pin versus time for the selected one of the gates and the step of adjusting can comprise recording and adjusting the position or drive rate of the actuators or valve pins associated with the other gates to approach or match the standard profile of position versus time. 
     
     
         4 . The method of  claim 1 , wherein the actuator is a fluid driven actuator and a fluid driven valve system that regulates the flow of either gas or liquid to the actuator. 
     
     
         5 . The method of  claim 1 , wherein the actuator is a pneumatic actuator and a proportional valve regulates the flow of pneumatic fluid to the actuator. 
     
     
         6 . The method of  claim 1 , wherein the actuators control simultaneous flow of injection fluid material through each one of multiple nozzles into separate mold cavities or the same cavity. 
     
     
         7 . The method of  claim 1 , wherein the downstream sensor is a temperature sensor. 
     
     
         8 . The method of  claim 1 , wherein the downstream sensor is a pressure sensor. 
     
     
         9 . The method of  claim 1 , wherein the actuator is an electrically powered actuator. 
     
     
         10 . The method of  claim 1 , wherein the apparatus includes a controller with a memory and a program with instructions that store and use the standard amount of time elapsed for the subsequent injection cycles, and the controller performs the step of adjusting by automatically adjusting the position or velocity of the actuators or valve pins. 
     
     
         11 . The method of  claim 1 , wherein the controller is a closed loop controller and proportional valve driver that receives position signals from the position sensors to control the position and velocity of the actuators or valve pins. 
     
     
         12 . Apparatus for performing an injection molding cycle in an injection molding apparatus, the apparatus comprising:
 a manifold that receives an injection fluid material, the manifold having or communicating with a delivery channel that delivers the injection fluid mold material under an injection pressure to two or more gates each leading to an associated mold cavity,   an actuator associated with each respective gate,   each actuator being drivably interconnected to a valve pin drivable upstream and downstream along a path of travel having a selected stroke length that extends between a gate closed position, a selected maximum flow position at which the injection fluid material flows at a maximum rate through the gate into the cavity and one or more selectable intermediate positions between the first position and the maximum flow position,   each actuator being controllably drivable to position an interconnected valve pin at the first, one or more selectable intermediate and maximum flow positions over the course of an injection cycle,   a downstream sensor that senses a selected physical condition of the injection fluid material at a position within a mold cavity that is downstream of an associated gate, the downstream sensor generating a signal corresponding to the sensed values,   a controller including instructions for:
 selecting and recording as a standard for a selected one of the gates, the amount of time elapsed between movement of the valve pin associated with the selected one of the gates out of the gate closed position and the time at which the downstream sensor first senses the selected condition of the injection fluid material flowing into the associated mold cavity, 
 recording, based on signals received from the downstream sensors of each of the other gates on a subsequent injection cycle upon sensing the selected physical condition of the injection fluid material at the downstream position, the amount of time elapsed between movement of the valve pin associated with each of the other gates out of the gate closed position and the time at which the downstream sensor first senses the selected condition of the injection fluid material flowing into the associated cavities of each of the other gates, 
 comparing the recorded amounts of time elapsed associated with each of the other gates with the standard amount of time elapsed that is associated with the selected one of the gates, 
 adjusting position or velocity of the actuators or valve pins associated with each of the other gates during further subsequent injection cycles such that the amount of time elapsed between movement of the valve pins associated with each of the other gates of their gate closed position and the time at which the downstream sensor first senses the selected condition of the injection fluid material approaches or matches the selected standard amount of elapsed time, 
 wherein the step of recording the amount of time elapsed between movement of the valve pin and the time at which the downstream sensor first senses the selected condition comprises instructions for: 
 detecting movement of the valve pin by sensing position of the valve pin with a position sensor, 
 and wherein the step of adjusting position or velocity of the actuator or valve pin so that the amount of time elapsed approaches or matches the selected standard amount of elapsed time comprises instructions for: 
 adjusting the position of a distal tip end of the valve pin having a configuration that interacts with an interior surface of a respective gate area to provide a reduced rate of material flow along the path of travel in the one or more selectable intermediate positions. 
   
     
     
         13 . The apparatus of  claim 12 , wherein the actuator is a fluid driven actuator and a fluid driven valve system regulates the flow of either gas or liquid to the actuator. 
     
     
         14 . The apparatus of  claim 12 , wherein the actuator is a pneumatic actuator and a proportional valve regulates the flow of pneumatic fluid to the actuator. 
     
     
         15 . The apparatus of  claim 12 , wherein the actuators control simultaneous flow of injection fluid material through each one of multiple nozzles into separate mold cavities or the same cavity. 
     
     
         16 . The apparatus of  claim 12 , wherein the downstream sensor is a temperature sensor. 
     
     
         17 . The apparatus of  claim 12 , wherein the downstream sensor is a pressure sensor. 
     
     
         18 . The apparatus of  claim 12 , wherein the actuator is an electrically powered actuator. 
     
     
         19 . The apparatus of  claim 12 , wherein the controller has a memory and a program with instructions that store and use the standard amount of time elapsed for the subsequent injection cycles, and the controller performs the step of adjusting by automatically adjusting the position or velocity of the actuators or valve pins. 
     
     
         20 . The apparatus of  claim 12 , wherein the controller is a closed loop controller and proportional valve driver that receives position signals from the position sensors to control the position and velocity of the actuators or valve pins.