Injection molding flow control apparatus and method

Abstract

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 having a fluid delivery channel, an actuator interconnected to a valve pin having a tip end drivable between a first position, a second position upstream and a third position upstream of the second position, the actuator and the valve pin being translationally driven by a valve system adjustable between a start position, a plurality of intermediate drive rate positions and a high drive rate position, a pressure sensor and a controller, the pressure sensor sensing a metered pressure of a drive fluid, the controller instructing the valve system to drive valve pin continuously upstream and including instructions that instruct the valve system to move according to a predetermined profile of metered pressures from the start position to selected intermediate drive rate positions and subsequently to the high drive rate position.

1 . 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 drivable at a controllable rate of travel by a valve system that is controllably adjustable between a start position, a plurality of intermediate drive rate positions and a high drive rate position, the actuator being drivable upstream and downstream at a corresponding plurality of intermediate rates of travel when the valve system is in one or more of the plurality of intermediate drive rate positions and at a higher rate of travel than the plurality of intermediate rates of travel when the valve system is in the high drive rate position;   a position sensor or an injection fluid condition sensor,   a pressure sensor,   a controller,   the position sensor sensing the position of the valve pin and sending a signal indicative of the position or the injection fluid of the pin to the controller or the injection condition sensor sending a signal indicative of a selected condition of the injection fluid to the controller;   the pressure sensor sensing a metered pressure of a drive fluid flowing out of an exit of the valve system, the metered pressure corresponding to a drive rate position of the valve system, the pressure sensor sending a signal indicative of the metered pressure 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 or continuously downstream from the third position to the second position;   the controller including instructions that instruct the valve system to move upstream or downstream either (a) from the start position to one or more of the plurality of the intermediate drive rate positions that correspond to the profile of metered pressures or (b) from the third position to one or more of the intermediate drive rate positions that correspond to the profile of metered pressures.   
     
     
         2 . The apparatus of  claim 1  wherein the one or more intermediate drive rate positions include a stop drive position wherein the drive fluid is shut off from driving the actuator. 
     
     
         3 . The apparatus of  claim 1  wherein the metered pressure corresponding to the stop drive position is zero or about zero. 
     
     
         4 . The apparatus of  claim 1  further comprising an electrical signal generating device interconnected to the valve system to controllably drive the valve system to selected degrees of openness, the electrical signal generating device generating an electrical signal of controllably variable degree of output, the valve system being adjustable in degree of openness that is approximately proportional to the degree of output of the electrical signal. 
     
     
         5 . The apparatus of  claim 4  wherein the electrical signal generating device is interconnected to the controller, the controller instructing the electrical signal generating device to generate electrical signals of varying degrees of output that correspond to a degree of openness of the one or more intermediate drive rate positions and the third drive rate position of the valve system. 
     
     
         6 . The apparatus of  claim 1  wherein the portion of the drive path over which the flow of injected material is restricted is at least about 30% of the length of the drive path between the first position and the second position. 
     
     
         7 . The apparatus of  claim 1  wherein the length of the drive path between the first position and the second position is between about 1 mm and about 5 mm. 
     
     
         8 . The apparatus of  claim 1  wherein the rate of travel of the valve pin corresponding to the highest of the one or more intermediate drive positions of the valve system is less than about 75% of the rate of travel of the valve pin corresponding to the high drive position. 
     
     
         9 . The apparatus of  claim 1  wherein the positions of the valve system each have a different degree of openness, the actuator and valve pin being driven at a velocity that is proportional to the degree of openness of the positions of the valve system, the controller instructing the generation of an electrical signal that adjusts the valve system to a degree of openness that is proportional to a degree of output of the electrical signal, the controller being programmable to instruct the generation of one or more first electrical signals having one or more corresponding first selected degrees of output that moves the valve system to the one or more intermediate drive rate positions to drive the actuator at one or more first velocities in an upstream or downstream direction, the controller being programmed to instruct the generation of a second electrical signal when the controller receives a signal from the position sensor that the tip end of the valve pin has reached the second position, the second electrical signal having a second selected degree of output that moves the valve system to the high drive rate position that drives the actuator at a second velocity that is higher than the one or more first velocities. 
     
     
         10 . A method of controlling operation of the valve system of the apparatus of  claim 1  comprising operating the apparatus of  claim 1  to cause the actuator and the valve pin to be translationally driven at a rate of travel that is adjustable between either the start position and the plurality of intermediate drive rate positions or between the high drive rate position and the plurality of intermediate drive rate positions. 
     
     
         11 . An apparatus for controlling the rate of flow of mold material to a mold cavity, the apparatus comprising:
 an injection molding machine and a manifold that receives the injected mold material from the machine, the manifold having a delivery channel that delivers the mold material at one or more flow rates through a gate to the mold cavity,   an actuator interconnected to a valve pin having a tip end, the actuator being drivable to move the valve pin along a path of travel starting from a downstream gate closed position continuously upstream to and through one or more intermediate gate open positions or starting from an upstream gate open position continuously downstream to and through one or more intermediate gate open positions,   a valve system in fluid communication with the actuator to drive the actuator with drive fluid at one or more rates of travel, the valve system having a start position, a plurality of intermediate drive rate positions and a high drive rate position, the start position holding the valve pin in the gate closed position, the high drive rate position driving the actuator upstream or downstream at a selected high velocity, the plurality of intermediate drive rate positions driving the actuator upstream or downstream at one or more corresponding velocities that are less than the selected high velocity,   a controller interconnected to the valve system, the controller being adapted to control movement of the valve system between the start position, the plurality of intermediate drive rate positions and the high drive rate position,   a pressure sensor sensing a metered pressure of a drive fluid flowing out of an exit of the valve system, the metered pressure corresponding to a drive rate position of the valve system, the pressure sensor sending a signal indicative of the metered pressure to the controller;   the controller including instructions that instruct the valve system to move either (a) from the start position to one or more of the plurality of intermediate drive rate positions according to a predetermined profile of metered pressures versus one or more preselected amounts of time or (b) from the high drive rate position to one or more of the plurality of intermediate drive rate positions according to a predetermined profile of metered pressures versus one or more preselected amounts of time.   
     
     
         12 . The apparatus of  claim 11  wherein the positions of the valve system each have a corresponding degree of openness, the controller being adapted to generate an electrical signal of selectable degree of output, the degree of openness of the positions of the valve system being proportional to the degree of output of the electrical signal generated by the controller. 
     
     
         13 . The apparatus of  claim 12  wherein the output of the electrical signal is one or more of electrical energy, electrical power, voltage, current or amperage. 
     
     
         14 . The apparatus of  claim 12  wherein the degree of openness of the positions of the valve system each have a corresponding rate of flow of the drive fluid that is proportional to the corresponding degree of openness of the positions of the valve system. 
     
     
         15 . The apparatus of  claim 11  wherein
 the tip end of the valve pin obstructs the gate to prevent the mold material from flowing into the cavity in the first position, the mold material flows at the high rate through the gate in the second position and the tip end of the valve pin restricts the flow of the mold material to less than the high rate in the one or more intermediate upstream positions between the first position and the second position, and 
 wherein the valve pin is in one or more of the intermediate positions when the valve system is in the one or more intermediate drive rate positions. 
 
     
     
         16 . The apparatus of  claim 11  wherein the rate of travel of the actuator that corresponds to a highest of the one or more intermediate drive rate positions of the valve system is less than about 75% of the rate of travel of the actuator that corresponds to the high drive rate position of the valve system. 
     
     
         17 . The apparatus of  claim 11  wherein the one or more intermediate drive rate positions include a stop drive position wherein the drive fluid is shut off from driving the actuator. 
     
     
         18 . The apparatus of  claim 17  wherein the metered pressure corresponding to the stop drive position is zero or about zero. 
     
     
         19 . A method of controlling operation of the valve system of the apparatus of  claim 11  comprising operating the apparatus of  claim 11  to cause the actuator and the valve pin to be translationally driven at a rate of travel that is adjustable between either the start position and the plurality of intermediate drive rate positions or between the high drive rate position and the plurality of intermediate drive rate positions. 
     
     
         20 . 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 drivable at a controllable rate of travel by a valve system that is controllably adjustable between a start position, a plurality of intermediate drive rate positions and a high drive rate position, the actuator being drivable upstream and downstream at a corresponding plurality of intermediate rates of travel when the valve system is in one or more of the plurality of intermediate drive rate positions and at a higher rate of travel than the plurality of intermediate rates of travel when the valve system is in the high drive rate position;   a pressure sensor,   a controller,   the pressure sensor sensing a metered pressure of a drive fluid flowing out of an exit of the valve system, the metered pressure corresponding to a drive rate position of the valve system, the pressure sensor sending a signal indicative of the metered pressure 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 or continuously downstream from the third position to the second position;   the controller including instructions that instruct the valve system to move upstream or downstream either (a) from the start position to one or more of the plurality of the intermediate drive rate positions that correspond to the profile of metered pressures or (b) from the third position to one or more of the intermediate drive rate positions that correspond to the profile of metered pressures.   
     
     
         21 . A method of controlling operation of the valve system of the apparatus of  claim 20  comprising operating the apparatus of  claim 20  to cause the actuator and the valve pin to be translationally driven at a rate of travel that is adjustable between either the start position and the plurality of intermediate drive rate positions or between the high drive rate position and the plurality of intermediate drive rate positions. 
     
     
         22 . 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, one or more intermediate positions 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 intermediate position,   a pressure sensor,   a controller,   the pressure sensor sensing a metered pressure of a drive fluid flowing out of an exit of the valve system, the metered pressure corresponding to a drive rate position of the valve system, the pressure sensor sending a signal indicative of the metered pressure to the controller:   the controller including instructions that instruct the valve system to drive the actuator and the valve pin to be disposed or held 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 according to a profile of metered pressures.   
     
     
         23 . A method of controlling operation of the valve system of the apparatus of  claim 22  comprising operating the apparatus of  claim 22  to cause the actuator and the valve pin to be disposed in the selected intermediate position for the selected period of time.