Sequential Injection to Multiple Mold Cavities

Abstract

An injection molding apparatus, comprising: an injection molding machine; a distribution manifold having a distribution channel, a clamp device arranged to clamp together, under a selected clamp force, a mold system having a plurality of mold cavities one or more first downstream channels fluidly coupled to the distribution channel; one or more first gates arranged to deliver injection fluid to a first cavity; one or more second downstream channels fluidly coupled to the distribution channel; one or more second gates arranged to deliver injection fluid to a second cavity; a control system adapted to: instruct the first upstream valve and a second upstream valve; and at least one downstream valve having a valve pin having a control surface for controlling flow of injection fluid.

Claims

1. An injection molding apparatus, comprising: an injection molding machine; a distribution manifold having a distribution channel, the distribution manifold arranged to receive injection fluid from the injection molding machine and further arranged to route injection fluid downstream via the distribution channel; a clamp device arranged to clamp together, under a selected clamp force, a mold system having a plurality of mold cavities; one or more first downstream channels fluidly coupled to the distribution channel; one or more first gates, each first gate associated with a respective first downstream channel and arranged to deliver injection fluid to a first cavity of the mold system; one or more second downstream channels fluidly coupled to the distribution channel; one or more second gates, each second gate associated with a respective second downstream channel and arranged to deliver injection fluid to a second cavity of the mold system; one or more downstream valves associated with each of the first and second downstream channels, the one or more downstream valves arranged to control delivery of injection fluid through the respective first and second downstream channels and associated first and second gates; a first upstream valve arranged to enable and disable a first flow of injection fluid from the distribution channel to the one or more first gates; a second upstream valve arranged to enable and disable a second flow of injection fluid from the distribution channel to the one or more second gates, wherein at least one of the valves has an actuator and a valve pin interconnected to the actuator, wherein the valve pin has a control surface with a selected configuration adapted to cooperate with a selected complementary surface of a respective channel, and wherein at least one rate of flow of injection fluid is controllable by controlling axial positioning of the control surface of the valve pin relative to the selected complementary surface of the respective channel; and a control system adapted to: instruct the first upstream valve to enable flow of injection fluid to the one or more first gates at a first selected time; and instruct the second upstream valve to enable flow of injection fluid to the one or more second gates at a second selected time that is delayed, subsequent, or sequential in time relative to the first selected time during an injection cycle.

2. An apparatus according to claim 1 wherein at least one of the first selected time and the second selected time is selected to provide one or both of a first peak time that is offset from a second peak time or a first pack phase time that is offset from a second pack phase time, wherein the first peak time is when a first peak injection fluid force or pressure occurs within the first cavity during the injection cycle, wherein the second peak time is when a second peak injection fluid force or pressure occurs within the second cavity during the injection cycle, wherein the first pack phase time is when a first pack phase injection fluid force or pressure occurs within the first cavity during the injection cycle, and wherein the second pack phase time is when a second pack phase injection fluid force or pressure occurs within the second cavity during the injection cycle.

3. An apparatus according to claim 2 wherein a maximum cumulative fluid force or pressure that occurs within the first and second cavities during the injection cycle is less than a cumulation of the first and second peak injection fluid forces or pressures.

4. An apparatus according to claim 1 wherein injection fluid is injected into the first and second cavities first under a filling phase pressure or force and subsequently under a pack phase pressure or force, the filling phase pressure or force being substantially less than the pack phase pressure or force.

5. An apparatus according to claim 1 wherein the selected clamp force is at least equal to a cumulative peak force or pressure exerted by injection fluid within all of the plurality of mold cavities of the mold system over the injection cycle.

6. An apparatus according to claim 1 wherein at least one of the first selected time and the second selected time is selected to provide a time during the injection cycle at which injection fluid exerts a peak force or pressure within the first cavity that is substantially offset from a time during the injection cycle at which injection fluid exerts a peak force or pressure within the second cavity.

7. An apparatus according to claim 1 wherein at least one of the first selected time and the second selected time is selected to significantly reduce the selected force of the clamp device relative to a force equal to a combined peak force or pressure exerted by injection fluid within each of the plurality of cavities when injection fluid is delivered to the one or more first gates and the one or more second gates concurrently.

8. An apparatus according to claim 1 wherein the control system is further adapted to perform at least one additional act, the at least one additional act including: control timing of opening of one or more upstream valves to deliver injection fluid to at least some of the plurality of mold cavities at and over different or staggered times during the injection cycle; control a degree of openness of one or more upstream valves to deliver injection fluid to at least some of the mold cavities at different selected times during the injection cycle; control a degree of openness of one or more upstream valves to deliver injection fluid to at least some of the mold cavities at different selected rates during the injection cycle; receive fluid pressure data from one or more pressure sensors arranged to measure fluid pressure at a selected position disposed within an upstream distribution channel; control a degree of openness of one or more upstream valves during the injection cycle to deliver injection fluid to at least some of the mold cavities at different selected fluid pressures at certain selected positions to match a predetermined profile of pressures; and control axial positioning of at least one valve pin to control a sequence or timing of injection fluid flow.

9. An apparatus according to claim 1, further comprising: one or more pressure sensors interconnected to the control system and arranged to measure fluid pressure within a downstream fluid channel, the one or more pressure sensors disposed upstream and away from at least one of the first and second gates; and a memory arranged to store a predetermined profile of fluid pressures, wherein the control system is further adapted to: instruct the actuator to axially position the valve pin to effect a fluid pressure at the upstream and away from a position of the at least one of the first and second gates that matches the predetermined profile of fluid pressures.

10. An apparatus according to claim 1, further comprising: one or more pressure sensors interconnected to the control system and arranged to measure fluid pressure at one or more determined positions within a cavity; and a memory arranged to store a predetermined profile of fluid pressures for the one or more determined positions at which the one or more pressure sensors measure pressure, wherein the control system is further adapted to: instruct the respective actuator of the at least one downstream valve to axially move the respective valve pin to positions that cause the pressure of fluid at the determined position within the cavity to match corresponding pressures of the predetermined profile.

11. A method to perform an injection cycle, comprising: clamping a mold system together under a selected clamp force with a clamp device, the mold system having a plurality of mold cavities; routing injection fluid via a common distribution channel to one or more first downstream channels, the one or more first downstream channels having respective associated first downstream valves and first gates that deliver injection fluid to a first cavity of the mold system; routing injection fluid to one or more second downstream channels having respective associated second downstream valves and second gates that deliver injection fluid to a second cavity of the mold system; enabling and disabling flow of injection fluid to the one or more associated first gates via a first upstream valve, wherein enabling flow of injection fluid to the one or more associated first gates includes instructing the first upstream valve to enable flow of injection fluid to the one or more associated first gates at a first selected time; enabling and disabling flow of injection fluid to the one or more associated second gates via a second upstream valve wherein enabling flow of injection fluid to the one or more associated second gates includes instructing the second upstream valve to enable flow of injection fluid to the one or more associated second gates at a second selected time that is delayed, subsequent, or sequential in time relative to the first selected time during the injection cycle; and at least one of the valves having an actuator and a valve pin interconnected to the actuator, wherein the valve pin has a control surface with a selected configuration adapted to cooperate with a selected complementary surface of the respective channel, controlling at least one rate of flow of injection fluid in the respective channel by controlling axial positioning of the control surface of the valve pin relative to the selected complementary surface of the downstream channel.

12. A method according to claim 11 wherein the selected clamp force is at least equal to a cumulative peak force or pressure exerted by injection fluid within all of the plurality of mold cavities of the mold system over the injection cycle.

13. A method according to claim 11, further comprising: selecting one or both one of the first selected time and the second selected time to reduce the selected force of the clamp device relative to a force equal to a combined peak force or pressure exerted by injection fluid within each of the plurality of mold cavities when injection fluid is delivered to the one or more first gates and the one or more second gates concurrently.

14. A method according to claim 11, further comprising: selecting one or both one of the first selected time and the second selected time to provide a first peak injection fluid force or pressure within the first cavity at a first peak time during the injection cycle and to provide a second peak injection fluid force or pressure within the second cavity at a second peak time during the injection cycle, wherein the first peak time is offset from the second peak time.

15. A method according to claim 12, further comprising: selecting one or both one of the first selected time and the second selected time to provide a maximum cumulative fluid force or pressure within the first and second cavities during the injection cycle that is less than a cumulation of first and second peak injection fluid forces or pressures.

16. A method according to claim 11, further comprising: selecting one or both one of the first selected time and the second selected time to provide a first pack phase injection fluid force or pressure within the first cavity at a first pack phase time during the injection cycle and to provide a second pack phase injection fluid force or pressure within the second cavity at a second pack phase time during the injection cycle, wherein the first pack phase time is offset from the second pack phase time.

17. A method according to claim 11 further comprising injecting injection fluid into the first and second cavities first under a filling phase pressure or force and subsequently under a pack phase pressure or force, the filling phase pressure or force being substantially less than the pack phase pressure or force.

18. An injection molding system, comprising: a clamp device arranged to clamp a plurality of mold cavities together under a selected clamp force; a distribution channel integrated in a distribution manifold and arranged to route injection fluid downstream; a plurality of downstream channels fluidly coupled to the distribution channel, the plurality of downstream channels including at least one first downstream channel and at least one second downstream channel; first and second gates associated, respectively, with each first and second downstream channel and arranged to pass injection fluid, respectively, to first and second cavities of the plurality of mold cavities; first and second downstream valves associated with each of the first and second downstream channels, the first and second downstream valves arranged to control delivery of injection fluid through the respective first and second downstream channels and associated first and second gates; first and second upstream valves controllably arranged, respectively, to pass first and second flows of injection fluid, respectively, from the distribution channel to each first and second gate, wherein at least one of the valves has an actuator and a valve pin interconnected to the actuator, wherein the valve pin has a control surface with a selected configuration adapted to cooperate with a selected complementary surface of a respective channel, and wherein at least one rate of flow of injection fluid is controllable by controlling axial positioning of the control surface of the valve pin relative to the selected complementary surface of the respective channel; and a control system adapted to instruct the first upstream valve to enable the first flow of injection fluid at a first selected time and instruct the second upstream valve to enable the second flow of injection fluid at a second selected time that is delayed, subsequent, or sequential in time relative to the first selected time during an injection cycle.

19. An injection molding system according to claim 18 wherein the selected clamp force is at least equal to a cumulative peak force or pressure exerted by injection fluid within all of the plurality of mold cavities over the injection cycle.

20. An injection molding system according to claim 18 wherein at least one of the first selected time and the second selected time is selected to reduce the selected force of the clamp device relative to a force equal to a combined peak force or pressure exerted by injection fluid within each of the plurality of cavities when injection fluid is delivered to the first and second gates concurrently.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] FIG. 1A is a plot of clamp force versus time that is required and occurs during an injection cycle in a system comprised of first and second mold cavities held within a common or single clamp device and where each cavity is separately gated by first and second gate systems each gate system being comprised of two or more gates that are sequentially opened to fill each cavity, and where each gate system is simultaneously fed or opened during a filling stage.

[0056] FIG. 1B is a plot of clamp force versus time that is required and occurs during an injection cycle in the system comprised of the same pair of mold cavities as in FIG. 1A held within the same common or single clamp device where each gate system to the pair of mold cavities is fed or opened during the filling stage for each cavity in a time sequenced or sequential manner such that the clamp forced required to hold the cavities closed is substantially reduced relative to the clamp force required to carry out the simultaneous process resulting in the FIG. 1 plot.

[0057] FIG. 2A is a schematic plot of injection fluid density flow and a recordation of cavity pressure recorded at a selected time around or near the beginning of the injection cycle performed using the first and second cavity system of FIGS. 1A, 1B and the simultaneous opening or feeding of the first and second gate systems during the filling stage used to generate the plot of FIG. 1A.

[0058] FIG. 2B is a schematic plot of injection fluid density flow and a recordation of cavity pressure recorded at another selected time around or near the beginning of the injection cycle performed using the first and second cavity system of FIGS. 1A, 1B and the sequential opening or feeding of the first and second gate systems during the filling stage used to generate the plot of FIG. 1B.

[0059] FIG. 3A is a schematic plot of injection fluid density flow and a recordation of cavity pressure recorded at a selected second subsequent time during the injection cycle performed using the first and second cavity system of FIGS. 1A, 1B and the simultaneous opening or feeding of the first and second gate systems during the filling stage used to generate the plot of FIG. 1A.

[0060] FIG. 3B is a schematic plot of injection fluid density flow and a recordation of cavity pressure recorded at another selected second subsequent time during the injection cycle performed using the first and second cavity system of FIGS. 1A, 1B and the sequential opening or feeding of the first and second gate systems during the filling stage used to generate the plot of FIG. 1B.

[0061] FIG. 4A is a schematic plot of injection fluid density flow and a recordation of cavity pressure recorded at a selected third subsequent time during the injection cycle performed using the first and second cavity system of FIGS. 1A, 1B and the simultaneous opening or feeding of the first and second gate systems during the filling stage used to generate the plot of FIG. 1A.

[0062] FIG. 4B is a schematic plot of injection fluid density flow and a recordation of cavity pressure recorded at another selected third subsequent time during the injection cycle performed using the first and second cavity system of FIGS. 1A, 1B and the sequential opening or feeding of the first and second gate systems during the filling stage used to generate the plot of FIG. 1B.

[0063] FIG. 5A is a schematic plot of injection fluid density flow and a recordation of cavity pressure recorded at a selected fourth subsequent time during the injection cycle performed using the first and second cavity system of FIGS. 1A, 1B and the simultaneous opening or feeding of the first and second gate systems during the filling stage used to generate the plot of FIG. 1A.

[0064] FIG. 5B is a schematic plot of injection fluid density flow and a recordation of cavity pressure recorded at another selected fourth subsequent time during an injection cycle performed using the first and second cavity system of FIGS. 1A, 1B and the sequential opening or feeding of the first and second gate systems during the filling stage used to generate the plot of FIG. 1B.

[0065] FIG. 6 is a side sectional schematic view of an injection molding apparatus according to the invention that includes a pair of upstream valves 108, 188 that are controlled to sequentially open or feed injection fluid 18 to separately controlled gates or gate systems 34,32 that deliver the injection fluid to first 300a and second 300b mold cavities, the upstream valves 108, 118 receiving a pressurized input of injection fluid 18 from the barrel of an injection molding machine 500.

[0066] FIG. 7 is a side partial sectional view of an upstream portion or surface 765 of a downstream fluid delivery channel 166 of a gate system 10a where a portion or surface 755 of the valve pin 1041a and the upstream portion or surface 765 of the channel 16 are complementarily configured to interact with each other depending on the axial position of the portion 755 of the valve pin to restrict and control the rate of flow of injection fluid 18 through the downstream channel and gate 34.

[0067] FIG. 8A is a side partially sectional schematic view of the downstream end of a downstream fluid delivery channel 166 having a gate surface area 1254 and a valve pin tip end surface 1155 complementarily configured to interact with each other depending on the axial position of the tip end surface 1155 to restrict and control the rate of injection fluid 18 through the downstream channel 166 and gate 34, the tip end surface 1155 being engaged and in contact with the gate surface area 1254 to close the gate 34 such that fluid flow is stopped.

[0068] FIG. 8B is a view similar to FIG. 8A showing the tip end surface 1155 being disposed in an axial position relative to the the gate surface area 1254 such that fluid flow 1154 can be restricted by controlled downstream or upstream movement of the pin through a path RP, RP2 of travel where the rate of fluid flow 1154 is restricted relative to the rate of flow when the valve pin 1041a is disposed in an upstream position such as an end of stroke EOS position.

DETAILED DESCRIPTION OF THE INVENTION

[0069] FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B illustrate the clamp force and injection fluid densities within a mold cavity that can occur over the course of an injection cycle using different injection protocols in the operation of an injection molding system comprised of a mold system having two or more separate cavities that are both clamped by a single clamp device.

[0070] In the context of the present disclosure, an injection cycle is the injection of a selected fluid into at least first and second selected mold cavities over a duration of time such that the selected injection fluid fills or substantially fills both the at least first and second selected mold cavities. For clarity, an injection cycle includes injection of fluid into a first selected cavity and filling or substantially filling the first selected cavity prior to completion of filling or substantially filling the second selected cavity. Filling or substantially filling a mold cavity includes injecting the injection fluid such that the injection fluid follows any profile of variable or varying fluid pressures exerted within a mold cavity or any profile of variable or varying flow velocities into the mold cavity over the duration of the injection cycle. A profile can include any one or a combination in any sequence of what may be referred to as high pressures, spike pressures, high flow velocities, fill pressures, fill velocities, low pressures, low flow velocities, low fill pressures, low fill velocities, pack pressures, pack velocities, and the like.

[0071] Shown on the right in FIGS. 1B, 2B, 3B, 4B, 5B is a clamp force plot, FIG. 1B and injection fluid density maps, FIGS. 2B, 3B, 4B, 5B that result at serial stages and times during an injection cycle where the pair of mold cavities are clamped or held within a single clamp device and are sequentially in time fed by or opened to fluid injection at or during the filing stage of an injection cycle, the source of injection fluid flow to each mold cavity being distributed from a common or single heated manifold. Shown on the left in FIGS. 1A, 2A, 3A, 4A, 5A is a clamp force plot, FIG. 1A and injection fluid density maps, FIGS. 2A, 3A, 4A, 5A that result at various serial or subsequent times during an injection cycle where the pair of mold cavities are fed by or opened to fluid injection simultaneously and not sequentially during the filling stage by a common or single heated manifold system.

[0072] The injection protocol used to generate the plots and maps of FIGS. 1A, 2A, 3A, 4A, 5A, is typically used in a conventional hot runner injection system process or protocol that doesn't utilize sequentially controlled upstream valves. As shown by FIGS. 1B, 2B, 3B, 4B, 5B, using a cavity isolator system, method and protocol according to the invention enables the implementation of a stable and reproducible predetermined profile of cavity or fluid delivery channel pressure that can be selectively different for each cavity during a single injection cycle. A first mold cavity can be substantially completely filled and enter a packing stage (which typically requires uniform pressure distribution) while injection of fluid to a second mold cavity during the same injection cycle can be carried out such that the second mold cavity is still in process of filling after the first mold cavity has already been substantially filled. This sequential in time mold cavity filling process enables the peak clamp force required for clamping or holding each mold at its peak stage of required fill pressure to be offset, reducing the size of the pressure spike seen in the left FIG. 1A that occurs when using a simultaneous injection to both cavities 300a, 300b during the filling stage in the system and method shown in FIGS. 2A, 3A, 3A, 4A. In a conventional manifold system and injection protocol as shown in FIGS. 2A, 3A, 3A, 4A, a downstream programmed injection protocol that separately controls injection sequentially downstream through one set of downstream gates 36 for one of the two cavities 300a would disturb the desired injection fluid pressure distribution within the other cavity 300b via the other set of gates 38 causing aesthetic defects and flow front stagnation.

[0073] As shown in FIG. 1A a spike of 2600 tons of clamp force is required to clamp against the cumulative fluid force or pressure that occurs within the two mold cavities 300a, 300b of the FIGS. 2A, 3A, 4A, 5A system and method of simultaneous injection. As shown such a spike occurs at about the time of 4.6 seconds where as shown in FIG. 5A the two cavities 300a, 300b are simultaneously in a pack phase at about 4.6 seconds during the course of an injection cycle. Such a simultaneous occurrence of peak fluid force or pressure within both cavities 300a, 300b is avoided in the sequentially filled cavity system and method of FIGS. 2B, 3B, 4B, 5B where the peak clamping force required during the injection cycle is about 2000 tons occurs at about 5.2 seconds at which the two mold cavities 300a, 300b are at significantly different stages of being filled. Thus in the sequentially filled system of FIGS. 2B, 3B, 4B, 5B the times at which a peak fluid force or pressure occurs within the two cavities are offset and the cumulative peak force or pressure that occurs with the two cavities is significantly reduced relative to the cumulative peak force or pressure that occurs in the system of FIGS. 2A, 3A, 4A, 5A.

[0074] FIG. 6 shows an injection molding apparatus 10a according to the invention that includes a pair of upstream valves 108, 118 that are interconnected to or controlled by a programmed controller 20 that controllably opens a pair of upstream valves 108, 118 that control the relative timing and the rate of fluid delivery to the downstream channels 166, 166a, 166b, 168, 168a, 168b and their associated gates 32, 32a, 32b, 34, 34a, 34b. The controlled upstream valves 108, 118 are controlled by controller 20 to begin an injection cycle in a predetermined sequence of time such that one of the valves 118 opens first to deliver injection fluid 18 at a first predetermined time to a first system of gates 34, 34a, 34b to a first mold cavity 300a and such that the other of the upstream valves 108 opens to deliver injection fluid 18 at a second subsequent predetermined time to a system of gates 32, 32a, 32b to a second mold cavity 300b. As shown the two mold cavities are mounted or clamped in a clamp device 700. The clamp device 700 holds the mold plates 302, 303 together under high force or pressure against the opposing high pressure of injection fluid 18 injected into the cavities 300a, 300b thus maintaining both of the cavities 300a, 300b closed at the same time during the course of an injection cycle.

[0075] As shown in schematic in FIGS. 2B, 3B, 4B, 5B, 6, injection fluid 18 is fed through the feed channel 503 of an inlet 502 to a heated manifold or hotrunner 800 that commonly feeds or delivers fluid 18 to the first and second cavities 300a and 300b. The manifold 800 includes an upstream runner channel 160 that is interconnected to and commonly feeds or delivers injection fluid 18 to downstream distribution channels 162, 164 that separately feed or deliver fluid 18 a first set of downstream feed channels 166, 166a, 166b and a second set of downstream feed channels 168, 168a, 168b respectively.

[0076] The upstream channel 160 first delivers the fluid 18 to the downstream distribution channels 162, 164 via controllable opening of the upstream valves 108, 118. One of the valves 108, 118 is first opened at a first time to enable flow of injection fluid 18 to a first set of downstream fluid channels and associated gates and the other of the valves 108, 118 is opened at a second subsequent time to enable flow of fluid 18 to the second set of downstream channels and associated gates. The valves 108, 118 can be further controlled by or comprise a servo valve or equivalent device 108s, 118s that can be controlled by controller 20 to open one or the other or both of the upstream valves 108s, 118s a selected degree of openness between 0 and 100% such that the rate of flow of injection fluid 18 can be controlled between 0 and 100% of the maximum rate of flow of the fluid. In such an embodiment controller 20 can be programmed to both open the upstream valves 108, 108s, 118, 118s at different or staggered time but also to selected degrees of openness over the course of an injection cycle. The controller can include an algorithm that receives fluid pressure data from pressure sensors such as sensors 60a, 80a that measure fluid pressure at a position within an upstream distribution channel 162, 164 that is disposed upstream and away from the gates 32, 34. The algorithm included within the controller 20 can include a memory that stores a predetermined profile of preferred fluid pressures at the positions at which sensors 60a, 80a are disposed and record pressure and the controller can included instructions that instruct the servo or other electronically controllable valves 108s, 118s to controllably open to a degree over the course of an injection cycle that results in a fluid pressure according to the stored profile of pressures at the location of the sensors 60a, 80a.

[0077] Similarly the controller 20 can include an algorithm that receives fluid pressure data from pressure sensors such as sensors 80c that that measure fluid pressure within a downstream fluid channel 166, 168 at a position 166ua disposed upstream and away from the gates 32, 34. The algorithm included within the controller 20 can include a memory that stores a predetermined profile of preferred fluid pressures at the positions at which sensors 80c are disposed and record pressure and the controller can further include instructions that instruct an actuator 50a, 50b that is interconnected to a valve pin 1041, 1041a having a configuration such as shown in FIG. 7 to move the pin surface 755 to axial positions relative to the complementary channel surface 765 that create a fluid pressure at the upstream channel position 166a that creates a fluid pressure that matched a stored predetermined profile of pressures at the location of position 166a.

[0078] Similarly the controller 20 can include an algorithm that receives fluid pressure data from pressure sensors such as sensors 60c that that measure fluid pressure at a position within a cavity 300a, 300b such as at a position disposed at or near the gates 32, 34. The algorithm included within the controller 20 can include a memory that stores a predetermined profile of preferred fluid pressures at the positions at which sensors 60c are disposed and record pressure during the course of an injections and the controller 20 can further include instructions that instruct an actuator 50a, 50b to move a valve pin 1041, 1041a having a configuration such as shown in either FIG. 7 or FIGS. 8A, 8B to move the pin 1041a axially to either position the surface 755 at axial positions relative to the complementary channel surface 765, or to position the valve tip surface 1155 relative to gate surface 1254 that create a fluid pressure at the position of the cavity sensors 60c that creates a fluid pressure that matches a stored predetermined profile of pressures at the position or location of sensors 60c.

[0079] In addition to a time sequence of fluid delivery as controlled by upstream valves 108s, 118s, the time sequence of delivery of injection fluid 18 through the downstream feed channels 166, 166a, 166b and 168, 168a, 168b can be further separately controlled by controlling the operation of actuators 50a, 50b that are associated with each feed channel 166, 166a, 166b and 168, 168a, 168b. The actuators 50a, 50b are interconnected to valve pins 1041, 1041a that can be configured to interact with either the gate area of gates 32, 34 or with a complementary upstream surface 765 as described with reference to FIGS. 7, 8A, 8B.

[0080] As shown in FIG. 7, the axial position of a valve pin 1041a, 1041 can be controlled to position a portion or surface 755 of the valve pin 1041a relative to a complementary portion or surface 765 of a downstream fluid delivery channel 166 that is disposed at a position 166ua upstream and away from the gate such that fluid flow through or past the surface 765 is controllably restricted to a selected rate of flow. As shown the portion or surface 755 of the valve pin 1041a and the upstream portion or surface 765 of the channel 16 are complementarily configured to interact with each other depending on the axial position of the portion 755 of the valve pin to restrict and control the rate of flow of injection fluid 18 past the surface 765 and thus also through the downstream channel 166 and gate 34. Such

[0081] FIG. 8A is a side partially sectional schematic view of the downstream end of a downstream fluid delivery channel 166 having a gate surface area 1254 and a valve pin tip end surface 1155 complementarily configured to interact with each other depending on the axial position of the tip end surface 1155 to restrict and control the rate of injection fluid 18 through the downstream channel 166 and gate 34, the tip end surface 1155 being engaged and in contact with the gate surface area 1254 to close the gate 34 such that fluid flow is stopped.

[0082] FIG. 8B is a view similar to FIG. 8A showing the tip end surface 1155 being disposed in an axial position relative to the gate surface area 1254 such that fluid flow 1154 can be restricted by controlled downstream or upstream movement of the pin through a path RP, RP2 of travel where the rate of fluid flow 1154 is restricted relative to the rate of flow when the valve pin 1041a is disposed in an upstream position such as an end of stroke EOS position.