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 delivery channel that delivers fluid material to a first gate;   an actuator interconnected to a valve pin having a tip end drivable along a drive path,   the actuator and the valve pin being translationally driven at a controllable rate of travel by a valve system comprised of 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 and a second position.

Description:
RELATED APPLICATIONS 
     This application is a continuation of and claims the benefit of priority to international application PCT/US13/56133 which in turn claims the benefit of priority to U.S. Provisional Application Ser. No. 61/692,957 filed Aug. 24, 2012, the disclosures of both of which are incorporated herein in their entirety by reference. This application is also a continuation-in-part of and claims the benefit of priority to U.S. application Ser. No. 13/484,336 filed May 31, 2012 (7100US1) the disclosure of which is incorporated herein by reference. This application is also a continuation-in-part of and claims the benefit of priority to U.S. application Ser. No. 13/484,408 filed May 31, 2012 (7100U53) the disclosure of which is incorporated herein by reference. 
     The disclosures of all of the following are incorporated by reference in their entirety as if fully set forth herein: U.S. Pat. No. 5,894,025, U.S. Pat. No. 6,062,840, U.S. Pat. No. 6,294,122, U.S. Pat. No. 6,309,208, U.S. Pat. No. 6,287,107, U.S. Pat. No. 6,343,921, U.S. Pat. No. 6,343,922, U.S. Pat. No. 6,254,377, U.S. Pat. No. 6,261,075, U.S. Pat. No. 6,361,300 (7006), U.S. Pat. No. 6,419,870, U.S. Pat. No. 6,464,909 (7031), U.S. Pat. No. 6,599,116, U.S. Pat. No. 6,824,379, U.S. Pat. No. 7,234,929 (7075US1), U.S. Pat. No. 7,419,625 (7075US2), U.S. Pat. No. 7,569,169 (7075US3), U.S. patent application Ser. No. 10/214,118, filed Aug. 8, 2002 (7006), U.S. Pat. No. 7,029,268 (7077US1), U.S. Pat. No. 7,270,537 (7077US2), U.S. Pat. No. 7,597,828 (7077US3), U.S. patent application Ser. No. 09/699,856 filed Oct. 30, 2000 (7056), U.S. Pat. No. 6,005,013, U.S. Pat. No. 6,051,174, U.S. Patent application publication no. 20020147244, U.S. patent application Ser. No. 10/269,927 filed Oct. 11, 2002 (7031), U.S. application Ser. No. 09/503,832 filed Feb. 15, 2000 (7053), U.S. application Ser. No. 09/656,846 filed Sep. 7, 2000 (7060), U.S. application Ser. No. 10/006,504 filed Dec. 3, 2001, (7068) and U.S. application Ser. No. 10/101,278 filed Mar. 19, 2002 (7070) and U.S. application Ser. No. 13/484,336 filed May 31, 2012 (7100US1) and U.S. application Ser. No. 13/484,408 filed May 31, 2012 (7100U53). 
    
    
     BACKGROUND OF THE INVENTION 
     Injection molding systems have been developed having flow control mechanisms that control the movement of a valve pin over the course of an injection cycle to cause the pin to move either upstream or downstream over the course of injection cycle in order to raise or lower the rate of flow of fluid material to correspond to a predetermined profile of fluid flow rates for the injection cycle. A sensor senses a condition of the fluid material or of the apparatus such as pin position and sends a signal indicative of the sensed condition to a program contained in a controller that uses the signal as a variable input to control movement of the valve pin in accordance with the predetermined profile. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention there is provided 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. 
     In accordance with the invention there is also provided 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. 
     In such a method, the step of adjusting the valve system to operate at the one or more selected intermediate drive rate positions is preferably begun after the injection fluid mold material has been previously injected into the cavity through another gate and the fluid mold material has travelled through the cavity past the first gate. The step of adjusting the valve system to operate at the one or more selected intermediate drive rate positions typically comprises adjusting the first valve to operate at a single intermediate drive rate position. 
     The high drive rate position of the valve system preferably drives the actuator at a rate of travel that is a maximum at which the valve system is capable of driving the actuator. The length of travel between the first position and the second position of the actuator along the drive path is typically selected to be between about 1 mm and about 5 mm. 
     The step of sensing typically includes sensing the position of the valve pin with a position sensor that automatically sends one or more signals indicative of the position of the tip end of the valve pin to a control mechanism that automatically adjusts the position of the second valve in response to receipt of the one or more signals from the position sensor. 
     The tip end of the valve pin preferably restricts flow of the injection fluid along the entire length of the drive path extending between the first position and the second position. 
     In another aspect of the invention there is provided 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 first position to the second 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. 
     Such an apparatus preferably further comprises an electrical signal generating device interconnected to the first valve to controllably adjust the first valve to a selected degrees of openness, the electrical signal generating device generating an electrical signal of controllably variable degree of output, the first valve being adjustable in degree of openness that is approximately proportional to the degree of output of the electrical signal. 
     The portion of the drive path over which the flow of injected material is restricted is typically at least about 30% of the length of the drive path between the first position and the second position. The length of the drive path between the first position and the second position is typically between about 1 mm and about 5 mm. The valve pin and actuator are typically driven at a maximum rate of upstream travel that the valve system is capable of driving the actuator at when the valve system is in the high drive rate position. 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 typically less than about 75% of the rate of travel of the valve pin corresponding to the high drive position. 
     In another aspect of the invention there is provided 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. 
     In another aspect of the invention there is provided 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, 
     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 that is indicative of the valve pin having reached the second position or an elapse of a predetermined amount of time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and further advantages of the invention may be better understood by referring to the following description in conjunction with the accompanying drawings in which: 
         FIG. 1  is a schematic, sectional view of one embodiment of the invention showing a pair of sequential gates showing a first gate entering the center of a cavity having been opened and shown closed such that a first shot of fluid material has entered the cavity and traveled past the position of a second sequential gate, the second gate shown being open with its valve pin having traveled along an upstream restricted flow path RP allowing a second sequential shot of fluid material to flow into and merge with the first shot of material within the cavity; 
         FIGS. 1A-1E  are schematic cross-sectional close-up views of the center and one of the lateral gates of the  FIG. 1  apparatus showing various stages of the progress of injection. 
         FIG. 2  is a schematic of an embodiment of the invention showing a hydraulically actuated valve pin in which one port of the actuator is connected to a valve  850  that is electronically controlled to controllably switch hydraulic drive fluid input to the actuator between a direct input at maximum pressure from a source of hydraulic fluid supply and an input from an intermediate manually adjustable flow restrictor valve  600  that reduces the maximum pressure input from the source of supply. 
         FIGS. 2A, 2B  are schematic cross-sectional views of the hydraulic valve system of  FIG. 2  showing in  2 A the switch valve  850  in a position where flow of drive fluid is routed during the upstream withdrawal half of an injection cycle through the restrictor valve  600  and showing in  2 B the switch valve  850  in a position where flow of drive fluid is routed directly from the source of hydraulic supply  14  at maximum drive pressure. 
         FIG. 2C  is a schematic cross-sectional view similar to  FIG. 2A  showing the directional valve in a position that routes the drive fluid through the restrictor valve  600  during the downstream closure half of the injection cycle. 
         FIGS. 3A-3B  show tapered end valve pin positions at various times and positions between a starting closed position as in  FIG. 3A  and various upstream opened positions, RP representing a selectable path length over which the velocity of withdrawal of the pin upstream from the gate closed position to an open position is reduced (via a controllable flow restrictor) relative to the velocity of upstream movement that the valve pin would normally have over the uncontrolled velocity path FOV when the hydraulic pressure is normally at full pressure and pin velocity is at its maximum; 
         FIGS. 4A-4B  show a system having a valve pin that has a cylindrically configured tip end, the tips ends of the pins being positioned at various times and positions between a starting closed position as in  FIG. 4A  and various upstream opened positions, RP wherein RP represents a path of selectable length over which the velocity of withdrawal of the pin upstream from the gate closed position to an open position is reduced (via a controllable flow restrictor or electric actuator) relative to the velocity of upstream movement that the valve pin would normally have over the uncontrolled velocity path FOV when the hydraulic pressure of a hydraulic actuator is normally at full pressure and pin velocity is at its maximum; 
         FIG. 5  is a plot of pin velocity versus position representing one example of the opening of a gate lateral to a central gate via continuous upstream withdrawal of a valve pin at one rate over an initial flow path RP and at another higher rate rate of upstream withdrawal of the valve pin beginning at a pin position of FOP and beyond when the fluid material flow is typically at a maximum unrestricted rate of flow through the open gate without any restriction or obstruction from the tip end of the pin. 
         FIGS. 6A-6B  show various embodiments of position sensors that can be used in a variety of specific implementations of the invention, the sensors shown in these figures being mounted so as to measure the position of the piston component of the actuator which is indicative of the position of the valve pin relative to the gate; 
         FIGS. 6C-6D  show embodiments using limit switches that detect and signal specific positions of the actuator that can be sued to determine velocity, position and switchover to higher openness of valve restrictor and/or upstream velocity of travel of the actuator and valve pin. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a system  10  with a central nozzle  22  feeding molten material melt flow from an injection molding machine (not shown) through a main inlet  18  to a distribution channel  19  of a manifold  40 . The distribution channel  19  commonly feeds three separate nozzles  20 ,  22 ,  24  which all commonly feed into a common cavity  30  of a mold  42 . One of the nozzles  22  is controlled by actuator  940  and arranged so as to feed into cavity  30  at an entrance point or gate that is disposed at about the center  32  of the cavity. As shown, a pair of lateral nozzles  20 ,  24  feed into the cavity  30  at gate locations that are distal  34 ,  36  to the center gate feed position  32 . 
     As shown in  FIGS. 1, 1A  the injection cycle is a cascade process where injection is effected in a sequence from the center nozzle  22  first and at a later predetermined time from the lateral nozzles  20 ,  24 . As shown in  FIG. 1A  the injection cycle is started by first opening the pin  1040  of the center nozzle  22  and allowing the fluid material  100  (typically polymer or plastic material) to flow up to a position the cavity just before  100   b  the distally disposed entrance into the cavity  34 ,  36  of the gates of the lateral nozzles  24 ,  20  as shown in  FIG. 1A . After an injection cycle is begun, the gate of the center injection nozzle  22  and pin  1040  is typically left open only for so long as to allow the fluid material  100   b  to travel to a position just past  100   p  the positions  34 ,  36 . Once the fluid material has travelled just past  100   p  the lateral gate positions  34 ,  36 , the center gate  32  of the center nozzle  22  is typically closed by pin  1040  as shown in  FIGS. 1B, 1C, 1D and 1E . The lateral gates  34 ,  36  are then opened by upstream withdrawal of lateral nozzle pins  1041 ,  1042  as shown in  FIGS. 1B-1E . As described below, the rate of upstream withdrawal or travel velocity of lateral pins  1041 ,  1042  is controlled as described below. 
     In alternative embodiments, the center gate  32  and associated actuator  940  and valve pin  1040  can remain open at, during and subsequent to the times that the lateral gates  34 ,  36  are opened such that fluid material flows into cavity  30  through both the center gate  32  and one or both of the lateral gates  34 ,  36  simultaneously. 
     When the lateral gates  34 ,  36  are opened and fluid material NM is allowed to first enter the mold cavity into the stream  102   p  that has been injected from center nozzle  22  past gates  34 ,  36 , the two streams NM and  102   p  mix with each other. If the velocity of the fluid material NM is too high, such as often occurs when the flow velocity of injection fluid material through gates  34 ,  36  is at maximum flow rate when the valve pin  1041  is withdrawn at maximum speed, a visible line or defect in the mixing of the two streams  102   p  and NM will appear in the final cooled molded product at the areas where gates  34 ,  36  inject into the mold cavity. By injecting NM at a reduced flow rate for a relatively short period of time at the beginning when the gate  34 ,  36  is first opened and following the time when NM first enters the flow stream  102   p , the appearance of a visible line or defect in the final molded product can be reduced or eliminated. 
     The rate or velocity of upstream withdrawal of pins  1041 ,  1042  starting from the closed position can be controlled by a combination of the use of interconnected valves that control the rate of flow of hydraulic or pneumatic actuator drive fluid to the fluid sealed cavities between the cylinder and the piston flange of the actuators. The three interconnected valves comprise a manually adjustable valve  600 , an automatically adjustable valve  850  and flow directional valve  14 . The manually adjustable valve  600  can be set to any desired position of openness (0-100%) by the user, the lesser or greater the degree of openness to which the valve  600  is adjusted, the slower or faster the rate R at which the piston of the actuator  941 ,  940 ,  942  is driven upstream and concomitantly the slower or faster the rate at which an associated valve pin  1041 ,  1040 ,  1042  is driven upstream. 
     A “controller,” as used herein, refers to electrical and electronic control apparati that comprise a single box or multiple boxes (typically interconnected and communicating with each other) that contain(s) all of the separate electronic processing, memory and electrical signal generating components that are necessary or desirable for carrying out and constructing the methods, functions and apparatuses described herein. Such electronic and electrical components include programs, microprocessors, computers, PID controllers, voltage regulators, current regulators, circuit boards, motors, batteries and instructions for controlling any variable element discussed herein such as length of time, degree of electrical signal output and the like. For example a component of a controller, as that term is used herein, includes programs, controllers and the like that perform functions such as monitoring, alerting and initiating an injection molding cycle including a control device that is used as a standalone device for performing conventional functions such as signaling and instructing an individual injection valve or a series of interdependent valves to start an injection, namely move an actuator and associated valve pin from a gate closed to a gate open position. In addition, although fluid driven actuators are employed in typical or preferred embodiments of the invention, actuators powered by an electric or electronic motor or drive source can alternatively be used as the actuator component. 
     The user programs controller  16  via data inputs on a user interface to instruct the hydraulic system  700  to drive pins  1041 ,  1042  at a preselected upstream velocity that is reduced relative to a maximum velocity that the hydraulic system is capable of driving the pins  1041 ,  1042  and then subsequently at the maximum velocity after an initial period of reduced withdrawal velocity. As described below, such reduced pin withdrawal rate or velocity can executed until a position sensor such as 951, 952 detects that an actuator  941 ,  952  or an associated valve pin (or another component), has reached a certain position such as the end point COP, COP2,  FIGS. 3B, 4B  of a restricted flow path RP, RP2 or until a predetermined amount of time has elapsed. A typical amount of time over which the pins are withdrawn at a reduced velocity is between about 0.01 and 0.10 second, the entire injection cycle time typically being between about 0.3 seconds and about 3 seconds, more typically between about 0.5 seconds and about 1.5 seconds. 
       FIG. 1  shows position sensors  950 ,  951 ,  952  for sensing the position of the actuator cylinders  941 ,  942  and their associated valve pins (such as  1041 ,  1042 ) and feed such position information to controller  16  for monitoring purposes. As shown, fluid material  18  is injected from an injection machine into a manifold runner  19  and further downstream into the bores  44 ,  46  of the lateral nozzles  24 ,  22  and ultimately downstream through the gates  32 ,  34 ,  36 . When the pins  1041 ,  1042  are withdrawn upstream to a position where the tip end of the pins  1041  are in a fully upstream open position such as shown in  FIG. 1D , the rate of flow of fluid material through the gates  34 ,  36  is at a maximum. However when the pins  1041 ,  1042  are initially withdrawn beginning from the closed gate position,  FIG. 1A , to intermediate upstream positions,  FIGS. 1B, 1C , a gap  1154 ,  1156  that restricts the velocity of fluid material flow is formed between the outer surfaces  1155  of the tip end of the pins  44 ,  46  and the inner surfaces  1254 ,  1256  of the gate areas of the nozzles  24 ,  20 . The restricted flow gap  1154 ,  1156  remains small enough to restrict and reduce the rate of flow of fluid material  1153  through gates  34 ,  36  to a rate that is less than maximum flow velocity over a travel distance RP of the tip end of the pins  1041 ,  1042  going from closed to upstream as shown in  FIGS. 1, 1B, 1C, 1E and 3B, 4B . 
     The pins  1041  can be controllably withdrawn at one or more reduced velocities (less than maximum) for one or more periods of time over the entirety of the length of the path RP over which flow of mold material  1153  is restricted. Preferably the pins are withdrawn at a reduced velocity over more than about 50% of RP and most preferably over more than about 75% of the length RP. As described below with reference to  FIGS. 3B, 4B , the pins  1041  can be withdrawn at a higher or maximum velocity at the end COP2 of a less than complete restricted mold material flow path RP2. 
     The trace or visible lines that appear in the body of a part that is ultimately formed within the cavity of the mold on cooling above can be reduced or eliminated by reducing or controlling the velocity of the pin  1041 ,  1042  opening or upstream withdrawal from the gate closed position to a selected intermediate upstream gate open position that is preferably 75% or more of the length of RP. 
     RP can be about 1-8 mm in length and more typically about 2-6 mm and even more typically 2-4 mm in length. As shown in  FIG. 2  in such an embodiment, a control system or controller  16  is preprogrammed to control the sequence and the rates of valve pin  1040 ,  1041 ,  1042  opening and closing. The controller  16  controls the rate of travel, namely velocity of upstream travel, of a valve pin  1041 ,  1042  from its gate closed position for at least the predetermined amount of time that is selected to withdraw the pin at the selected reduced velocity rate. 
     The velocity of withdrawal of the valve pins  1041 ,  1042  during the initial reduced velocity portion of the cycle is determined by the preselected setting of degree of openness of the flow restrictor valve  600 ,  FIGS. 1, 2, 2A, 2B . Adjustment of the flow restrictor valve  600  to less than 100% open thus reduces the rate and volume flow of pressurized hydraulic fluid to the actuator cylinders thus in turn reducing the velocity of upstream travel of the pins  1041 ,  1042  for the pre-selected period of time or the pre-selected length of upstream travel. 
     In embodiments where a position sensor is used, at the end of the travel or length of path RP, RP2, the position sensor or timer signals the controller  16 , the controller  16  determines that the end COP, COP2 has been reached and the valve  850  is activated to connect the hydraulic drive fluid directly to the hydraulic supply at maximum drive pressure and the valve pins  1041 ,  1042  are driven at maximum upstream velocity FOV in order to reduce the cycle time of the injection cycle. 
     The valve  600  typically comprises a restrictor valve that is controllably positionable anywhere between completely closed (0% open) and completely open (100% open). Adjustment of the position of the restrictor valve  600  is typically accomplished manually at the beginning of the cycle via a source of electrical power that controllably drives an electromechanical mechanism that causes the valve to rotate such as a rotating spool that reacts to a magnetic or electromagnetic field created by the electrical signal output of the controller  16 , namely an output of electrical energy, electrical power, voltage, current or amperage the degree or amount of which can be readily and controllably varied by conventional electrical output devices. The electro-mechanism is controllably drivable to cause the valve  600  to open or close to a degree of openness that is proportional to the amount or degree of electrical energy that is input to drive the electro-mechanism. The velocity of upstream withdrawal travel of the pins  1041 ,  1042  are in turn proportional to the degree of openness of the valve  600 . Thus the rate of upstream (or downstream) travel of the pins  1041 ,  1042  is proportional to the amount or degree of electrical energy that is input to the electro-mechanism that drives valves  600  to its preselected position at the beginning of the cycle. Thus the user preselects a reduced upstream velocity of the pins  1041 ,  1042  by inputting to the controller  16  a percentage of the maximum amount of electrical energy or power input (voltage or current) needed to open the valve  600  to 100% open. The user inputs such selections into the controller  16 . The user also selects the length of the path of travel RP, RP2 of the valve pin or the position of the valve pin or other component over the course of travel of which the valve  600  is to be maintained partially open and inputs such selections into the controller  16 . The controller  16  includes conventional programming or circuitry that receives and executes the user inputs. The controller may include programming or circuitry that enables the user to input as a variable a selected pin velocity rather than a percentage of electrical output, the programming of the controller  16  automatically converting the inputs by the user to appropriate instructions for reduced energy input to the electro-mechanism that drives the valve  600 . 
     Typically the user selects one or more reduced velocities that are less than about 90% of the maximum velocity (namely velocity when the valve  600  is fully open), more typically less than about 75% of the maximum velocity and even more typically less than about 50% of the maximum velocity at which the pins  1041 ,  1042  are drivable by the hydraulic system. The actual maximum velocity at which the actuators  941 ,  942  and their associated pins  1041 ,  1042  are driven is predetermined by selection of the size and configuration of the actuators  941 ,  942 , the size and configuration of the restriction valve  600  and the degree of pressurization and type of hydraulic drive fluid selected for use by the user. The maximum drive rate of the hydraulic system is predetermined by the manufacturer and the user of the system and is typically selected according to the application, size and nature of the mold and the injection molded part to be fabricated. 
     In the  FIG. 5A  example, the reduced pin velocity is selected as 50 mm/sec. In practice the actual velocity of the pin may or may not be precisely known, the Y velocity axis corresponding (and generally being proportional) to the degree of electrical energy input to the motor that controls the opening of the flow restriction valve, 100 mm/sec corresponding to the valve  600  being completely 100% open (and pin being driven at maximum velocity); and 50 mm/sec corresponding to 50% electrical energy input to the electromechanism that drives the restriction valve  600  to one-half of its maximum 100% degree of openness. In the  FIG. 5A  example, the path length RP over which the valve pin  1041 ,  1042  travels at the reduced 50 mm/sec velocity is 4 mm. After the pin  1041 ,  1042  has been driven to the upstream position COP position of about 4 mm from the gate closed GC position, the controller  16  instructs the electro-mechanism that drives the valve  600  (typically a magnetic or electromagnetic field driven device such as a spool) to open the restrictor valve  600  to full 100% open at which time the pin (and its associated actuator piston) are driven by the hydraulic system at the maximum travel rate 100 mm/sec for the predetermined, given pressurized hydraulic system. 
     The valves  600  can be adapted to be adjustable by hand by a user to a selected degree of openness. Alternatively the valves  600  can be adjustable remotely by a user by operation of a mechanical or an electromechanical drive mechanism that is interconnected to a mechanically adjustable member of which the valve  600  is comprised such as a ball having a flow channel which, depending on its degree of rotation within a complementary socket adjusts the degree or rate or volume of flow of drive fluid to the actuators  940 - 942 . The valves  600  are typically adapted to be adjustable to any one of a plurality of selectable stationary positions of degree of openness, the valves  600  remaining in a single stationary position selected by the user for the duration of one or more selected injection cycles. 
     The valves  600  are interconnected to automatically adjustable valves  850 . Valves  850  are movable between two positions FO and PO where the valve  850  is either directly connected FO to the source  14  of hydraulic drive fluid or indirectly connected PO to the source  14  first through a valve  600 . Whether directly connected in the FO position or indirectly in the PO position, valves  850  enable maximum full open flow of the drive fluid being received. Thus when the valves  850  are in the FO position the hydraulic system  14  drives the actuators and associated valve pins  1040 - 1041  at maximum velocity. The directional valves  750  are adjustable to control the direction of drive fluid flow to and from valves  850  and  600 . 
     The valves  850  are movable between at least two positions, FO and PO. In one embodiment, the valves can be moved between the FO and PO positions via a trigger or control mechanism  16  that automatically instructs a valve  850  to move between the FO and PO positions upon or according to receipt of a trigger signal from a position sensor such as  950 , 951 , 952  that can sense the axial position of an actuator  940 ,  941 ,  942  (or the valve pin  1040 ,  1041 ,  1042 ) or from a temperature or pressure sensor  1050  that can sense temperature or pressure of the injection fluid material in the mold cavity  30  or the temperature or pressure of an operational component of the apparatus such as the fluid distribution manifold or a nozzle. 
     The valves  850  are interconnected to the directional valves  750  and to the manually adjustable valves  600  such that when the valves  850  are in the FO position, the flow of drive fluid from source  14  bypasses the manually adjustable valves  600  and is routed directly and exclusively through valves  850 . When moved into the other of the two positions, namely the PO position, the automatically adjustable valves  850  enable and allow the directional valves  750  route the flow of drive fluid first through valves  600  which in turn routes the drive fluid through valves  850 . 
     In one embodiment, the valves  850  are set at the beginning of an injection cycle to the PO position, and one or more of valves  600  are set, typically manually (or electronically) by the user to a position or setting where the volume or rate of flow of the drive fluid through a valve  600  to valve  850  (and in turn to actuators  941 ,  940 ,  942 ) is less than 100%, for example 50%. This reduced rate of flow of drive fluid in turn concomitantly reduces the velocity of upstream withdrawal R of valve pins  1041 ,  1040 ,  1042 ,  FIGS. 1A-E , to less than 100% of the maximum velocity at which the hydraulic drive system of the apparatus is capable of driving the fluid drivable actuators  940 - 942 . For the same injection cycle, the trigger or control  16  is pre-set or programmed to instruct the valves  850  to move from the PO position to the FO position upon the occurrence of a preselected event such as an elapse of a pre-selected period of time or upon the detection by a sensor  950 - 952  of a piston of an actuator  1040 - 1042  having reached a pre-selected trigger position of upstream travel or upon a sensor  1050  having detected a pre-selected trigger temperature or pressure of injection fluid material. 
     In another embodiment, after the user selects the degree of openness to which valve  600  is set (typically manually), the user can preselect a period of time over which a valve pin such as downstream pin  1041  is to be driven at a less than 100% velocity beginning from the start of an injection cycle when the pin  1041  is in a gate closed position. 
     Or, alternatively, the user can preselect an upstream position of travel to which the actuator  941  (or valve pin  1041 ) can travel at which position, the position detector 951 signals the controller  16  which in turn triggers the valve  850  to automatically move or switch from the PO position to the FO. In such an embodiment, the user can thus control movement of a valve pin  1040 - 1042  to follow a velocity versus time profile such as shown in  FIG. 5 . 
     Preferably, the valve pin and the gate are configured or adapted to cooperate with each other to restrict and vary the rate of flow of fluid material  1153 ,  FIGS. 3A-3B, 4A-4B  over the course of travel of the tip end of the valve pin through the restricted velocity path RP. Most typically as shown in  FIGS. 3A, 3B  the radial tip end surface  1155  of the end  1142  of pin  1041 ,  1042  is conical or tapered and the surface of the gate  1254  with which pin surface  1155  is intended to mate to close the gate  34  is complementary in conical or taper configuration. Alternatively as shown in  FIGS. 4A, 4B , the radial surface  1155  of the tip end  1142  of the pin  1041 ,  1042  can be cylindrical in configuration and the gate can have a complementary cylindrical surface  1254  with which the tip end surface  1155  mates to close the gate  34  when the pin  1041  is in the downstream gate closed position. In any embodiment, the outside radial surface  1155  of the tip end  1142  of the pin  1041  creates restricted a restricted flow channel  1154  over the length of travel of the tip end  1142  through and along restricted flow path RP that restricts or reduces the volume or rate of flow of fluid material  1153  relative to the rate of flow when the pin  1041 ,  1042  is at a full gate open position, namely when the tip end  1142  of the pin  1041  has travelled to or beyond the length of the restricted flow path RP (which is, for example the 4 mm upstream travel position of  FIG. 5 ). 
     In one embodiment, as the tip end  1142  of the pin  1041  continues to travel upstream from the gate closed GC position (as shown for example in  FIGS. 3A, 4A ) through the length of the RP path (namely the path travelled for the predetermined amount of time), the rate of material fluid flow  1153  through restriction gap  1154  through the gate  34  into the cavity  30  continues to increase from 0 at gate closed GC position to a maximum flow rate when the tip end  1142  of the pin reaches a position FOP (full open position),  FIG. 5 , where the pin is no longer restricting flow of injection mold material through the gate. In such an embodiment, at the expiration of the predetermined amount of time when the pin tip  1142  reaches the FOP (full open) position  FIG. 5  the pin  1041  is immediately driven by the hydraulic system at maximum velocity FOV (full open velocity) typically such that the restriction valve  600  is opened to full 100% open. 
     In alternative embodiments, when the predetermined time for driving the pin at reduced velocity has expired and the tip  1142  has reached the end of restricted flow path RP2, the tip  1142  may not necessarily be in a position where the fluid flow  1153  is not still being restricted. In such alternative embodiments, the fluid flow  1153  can still be restricted to less than maximum flow when the pin has reached the changeover position COP2 where the pin  1041  is driven at a higher, typically maximum, upstream velocity FOV. In the alternative examples shown in the  FIGS. 3B, 4B  examples, when the pin has travelled the predetermined path length at reduced velocity and the tip end  1142  has reached the changeover point COP, the tip end  1142  of the pin  1041  (and its radial surface  1155 ) no longer restricts the rate of flow of fluid material  1153  through the gap  1154  because the gap  1154  has increased to a size that no longer restricts fluid flow  1153  below the maximum flow rate of material  1153 . Thus in one of the examples shown in  FIG. 3B  the maximum fluid flow rate for injection material  1153  is reached at the upstream position COP of the tip end  1142 . In another example shown in  FIG. 3B   4 B, the pin  1041  can be driven at a reduced velocity over a shorter path RP2 that is less than the entire length of the restricted mold material flow path RP and switched over at the end COP2 of the shorter restricted path RP2 to a higher or maximum velocity FOV. In the  FIG. 5  example, the upstream FOP position is about 4 mm upstream from the gate closed position. Other alternative upstream FOP positions can be selected. 
     In another alternative embodiment, shown in  FIG. 4B , the pin  1041  can be driven and instructed to be driven at reduced or less than maximum velocity over a longer path length RP3 having an upstream portion UR where the flow of injection fluid mold material is not restricted but flows at a maximum rate through the gate  34  for the given injection mold system. In this  FIG. 4B  example the velocity or drive rate of the pin  1041  is not changed over until the tip end of the pin  1041  or actuator  941  has reached the changeover position COP3. As in other embodiments, a position sensor senses either that the valve pin  1041  or an associated component has travelled the path length RP3 or reached the end COP3 of the selected path length and the controller receives and processes such information and instructs the drive system to drive the pin  1041  at a higher, typically maximum velocity upstream. In another alternative embodiment, the pin  1041  can be driven at reduced or less than maximum velocity throughout the entirety of the travel path of the pin during an injection cycle from the gate closed position GC up to the end-of-stroke EOS position, the controller  16  being programmed to instruct the drive system for the actuator to be driven at one or more reduced velocities for the time or path length of an entire closed GC to fully open EOS cycle. 
     In the  FIG. 5  example, FOV is 100 mm/sec. Typically, when the time period for driving the pin  1041  at reduced velocity has expired and the pin tip  1142  has reached the position COP, COP2, the restriction valve  600  is opened to full 100% open velocity FOV position such that the pins  1041 ,  1042  are driven at the maximum velocity or rate of travel that the hydraulic system is capable of driving the actuators  941 ,  942 . Alternatively, the pins  1041 ,  1042  can be driven at a preselected FOV velocity that is less than the maximum velocity at which the pin is capable of being driven when the restriction valve  600  is fully open but is still greater than the selected reduced velocities that the pin is driven over the course of the RP, RP2 path to the COP, COP2 position. 
     At the expiration of the predetermined reduced velocity drive time, the pins  1041 ,  1042  are typically driven further upstream past the COP, COP2 position to a maximum end-of-stroke EOS position. The upstream COP, COP2 position is downstream of the maximum upstream end-of-stroke EOS open position of the tip end  1142  of the pin. The length of the path RP or RP2 is typically between about 2 and about 8 mm, more typically between about 2 and about 6 mm and most typically between about 2 and about 4 mm. In practice the maximum upstream (end of stroke) open position EOS of the pin  1041 ,  1042  ranges from about 8 mm to about 18 inches upstream from the closed gate position GC. 
     The controller  16  can comprise a timer or a more complex electrical or electronic control apparatus that comprises a single box or multiple boxes (typically interconnected and communicating with each other) that contain(s) all of the separate electronic processing, memory and electrical signal generating components that are necessary or desirable for carrying out the methods and functions and constructing the apparatuses described herein. Such electronic and electrical components include programs, microprocessors, computers, PID controllers, voltage regulators, current regulators, circuit boards, motors, batteries and instructions for controlling any variable element discussed herein such as length of time, degree of electrical signal output and the like. For example a component of a controller, as that term is used herein, includes programs, controllers and the like that perform functions such as monitoring, alerting and initiating an injection molding cycle including a control device that is used as a standalone device for performing conventional functions such as signaling and instructing an individual injection valve or a series of interdependent valves to start an injection, namely move an actuator and associated valve pin from a gate closed to a gate open position. 
       FIGS. 6A-6D  show various examples of position sensors  100 ,  114 ,  227 ,  132  the mounting and operation of which are described in U.S. Patent Publication no. 20090061034 the disclosure of which is incorporated herein by reference. As shown the position sensors shown in  FIGS. 6A and 6B  for example can track and signal the position of the piston of the actuator piston  223  continuously along its entire path of travel from which data pin velocity can be continuously calculated over the length of RP via spring loaded follower  102  that is in constant engagement with flange  104  during the course of travel of piston  223 . Mechanism  100  constantly sends signals to controller  16  in real time to report the position of pin  1041  and its associated actuator.  FIGS. 6C, 6D  show alternative embodiments using position switches that detect position at specific individual positions of the actuator and its associated valve pin  1041 . The  FIG. 6C  embodiment uses a single trip position switch  130   a  with trip mechanism  133  that physically engages with the piston surface  223   a  when the piston  223  reaches the position of the trip mechanism  133 . The  FIG. 6D  embodiment shows the use of two separate position switches  130   a ,  130   aa  having sequentially spaced trips  133   aa  and  133   aaa  that report the difference in time or distance between each trip engaging surface  223   a  of the piston, the data from which can be used by controller  16  to calculate velocity of the actuator based on the time of travel of the actuator from tripping one switch  130   a  and then tripping the next  130   aa . In each embodiment the position switch can signal the controller  16  when the valve pin  1041 ,  1042  has travelled to a selected upstream gate open position. As can be readily imagined other position sensor mechanisms can be used such as optical sensors, sensors that mechanically or electronically detect the movement of the valve pin or actuator or the movement of another component of the apparatus that corresponds to movement of the actuator or valve pin. 
     In alternative embodiments the controller  16  can comprise a processor and instructions that receive or record time elapse or pin position or temperature or pressure information signals from a sensor. The controller can calclulate the real time velocity of the pin from the pin position data in real time at one or more times or positions over the course of the pin travel through the RP path length and/or beyond. The controller  16  can alternatively comprise a simple trigger that acts in response to a signal received from from a sensor, the trigger causing the valve  850  to move to the FO position. In this embodiment as in all previously described embodiments, the pin is moved continuously upstream at all times between the gate closed position and the position at which valve  850  is switched from the PO position to the FO positions. And the pin is also moved continuously upstream at the maximum velocity at which the drive system is capable of driving the actuators when the valves  850  are in the FO position. Such control systems are described in greater detail in for example U.S. Patent Publication no. 20090061034 the disclosure of which is incorporated herein by reference.