Abstract
An injection molding system for implementing a molding process, comprising: a mold, a controller, a position sensor, wherein during an injection cycle, the system feeds the fluid material to one or more nozzles at one or more predetermined times, the controller being configured to receive and process the output signal from the position sensor to determine one or more actual flow rate indicative parameters, a user interface that displays one or more pin positions and one or more flow rate indicative parameters by which a user of the system can track the one or more pin positions and flow rate indicative parameters in real time during the injection cycle.
Claims
1. An injection molding system for implementing a molding process, comprising: a mold having one or more gates and one or more associated nozzles through which an injection fluid material is injected into a cavity of the mold during an injection cycle, each nozzle having an associated valve pin driven by an associated actuator between a gate closed position and an upstream end of stroke position, a controller that controls movement of the valve pins over the course of the injection cycle in accordance with a set of predetermined flow rate indicative parameters, a position sensor associated with each valve pin for monitoring pin position with respect to an associated gate and generating an output signal indicative of actual pin positions as the valve pin moves between the gate closed and gate open positions, wherein during an injection cycle, the system feeds the fluid material to the one or more nozzles at one or more predetermined times, starting by opening the valve pin of a respective nozzle at an opening time and allowing the fluid material to flow into the cavity to form a molded part in the cavity, the controller being configured to receive and process the output signal from the position sensor to determine one or more actual flow rate indicative parameters, a user interface that receives information from the controller indicative of one or more pin positions in real time and displays the one or more pin positions and one or more flow rate indicative parameters by which a user of the system can track the one or more pin positions and flow rate indicative parameters in real time during the injection cycle.
2. The system of claim 1 wherein the one or more pin positions and flow rate indicative parameters include one or more of pin opening time, pin opening position, pin closed position and pin velocity.
3. The system of claim 1 wherein the controller processes the sensor output signal to generate a control signal to control the pin position.
4. The system of claim 3 wherein the controller includes a user interface for receiving user input for adjusting the control signal to control the pin position.
5. The system of claim 1 wherein the user interface comprises a display of pin position, based on the sensor output signal, which includes pin open and closed positions and positions between the pin open and closed positions.
6. The system of claim 1 wherein the output signal from the sensor provides continuous monitoring of the pin position.
7. The system of claim 1 wherein the actuator comprises an electric motor comprising a rotatably drivable component interconnected to the valve pin in an arrangement wherein the pin is drivable along a linear path of travel between a gate closed position and an upstream end of stroke position.
8. The system of claim 1 wherein the mold has a center nozzle and one or more lateral nozzles routing the injection fluid into a common cavity, wherein during an injection cycle, the system feeds the fluid material to the center and one or more lateral nozzles at one or more predetermined times, starting by opening the valve pin of the center nozzle at a first selected opening time and allowing the fluid material to flow into the common cavity and opening the one or more lateral nozzles at one or more second selected opening times that is subsequent to the first selected opening time such that the fluid material is injected sequentially from the center nozzle and the one or more lateral nozzles such that the injection fluid material joins together to form a single molded part in a common cavity.
9. A method of performing an injection molding cycle comprising operating the system of claim 1.
10. An injection molding system for controlling the rate of flow of a fluid mold material from an injection molding machine to a cavity of a mold, the system comprising: a manifold receiving the injected fluid mold material, the manifold having a delivery channel that delivers the fluid mold material to a gate to the mold cavity; an actuator interconnected to a valve pin having a tip end, the actuator moving the valve pin upstream along a path of travel between a downstream gate closed position and one or more intermediate upstream gate open positions, the downstream gate closed position being a position wherein the tip end of the valve pin obstructs the gate to prevent fluid material from flowing into the mold cavity, the one or more intermediate upstream gate open positions being predetermined positions between the downstream gate closed position and an end of stroke position upstream of the intermediate upstream gate open position at which the fluid mold material flows at a selected maximum rate through the gate, wherein the gate is partially open when the valve pin is in the one or more intermediate upstream gate open positions; a position sensor that senses and generates signals indicative of position of the valve pin, a controller interconnected to the actuator and to the position sensor, the controller receiving the signals indicative of position of the valve pin and controlling movement of the actuator at least in part according to instructions that utilize the signals indicative of position of the valve pin to instruct the actuator to drive the valve pin upstream at one or more selected intermediate velocities over the course of a selected portion of the travel of the valve pin between the downstream gate closed position and the end of stroke position, the valve pin being drivable at a selected maximum upstream velocity, the one or more selected intermediate velocities being less than the selected maximum velocity, a user interface that receives information from the controller indicative of one or more pin positions in real time and displays the one or more pin positions and one or more flow rate indicative parameters by which a user of the system can track the one or more pin positions and flow rate indicative parameters in real time during the injection cycle.
11. The system of claim 10 wherein the one or more pin positions and flow rate indicative parameters include one or more of pin opening time, pin opening position, pin closed position and pin velocity.
12. The system of claim 10 wherein the controller processes the sensor output signal to generate a control signal to control the pin position.
13. The system of claim 12 wherein the controller includes a user interface for receiving user input for adjusting the control signal to control the pin position.
14. The system of claim 10 wherein the user interface comprises a display of pin position, based on the sensor output signal, which includes pin open and closed positions and positions between the pin open and closed positions.
15. The system of claim 10 wherein the output signal from the sensor provides continuous monitoring of the pin position.
16. The system of claim 10 wherein the actuator comprises an electric motor comprising a rotatably drivable component interconnected to the valve pin in an arrangement wherein the pin is drivable along a linear path of travel between a gate closed position and an upstream end of stroke position.
17. The system of claim 10 wherein the mold has a center nozzle and one or more lateral nozzles routing the injection fluid into a common cavity, wherein during an injection cycle, the system feeds the fluid material to the center and one or more lateral nozzles at one or more predetermined times, starting by opening the valve pin of the center nozzle at a first selected opening time and allowing the fluid material to flow into the common cavity and opening the one or more lateral nozzles at one or more second selected opening times that is subsequent to the first selected opening time such that the fluid material is injected sequentially from the center nozzle and the one or more lateral nozzles such that the injection fluid material joins together to form a single molded part in a common cavity.
18. A method of performing an injection molding cycle comprising operating the system of claim 10.
19. A method of performing an injection molding cycle in an injection molding apparatus comprising: an injection molding machine and a manifold that receives an injected mold material from the injection molding machine, the manifold having a delivery channel that delivers the mold material under an injection pressure to a first gate of a mold cavity, an actuator interconnected to a valve pin driving the valve pin from 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, the actuator further driving the valve pin upstream to a second position upstream of the gate where the mold material flows at a maximum rate through the gate and upstream from the start position through one or more intermediate positions between the first position and the second position wherein the tip end of the valve pin restricts flow of the injection fluid to one or more rates less than the maximum rate, a drive system for controllably driving the actuator and the valve pin upstream at one or more selected intermediate velocities and at one or more high velocities that are higher than the intermediate velocities, the method comprising: beginning an injection cycle with the tip end of the valve pin in the first position, sensing the position of the valve pin, adjusting the drive system to drive the actuator at the one or more intermediate velocities upstream to and through one or more of the intermediate positions at the one or more selected intermediate velocities in response to sensing of the position of the valve pin in the one or more of the intermediate positions.
20. The method of claim 19 wherein the actuator comprises an electrically driven motor.
21. The method of claim 19 wherein the actuator comprises a hydraulically or pneumatically driven actuator.
22. A method of performing an injection molding cycle comprising operating the apparatus of claim 1 to inject the fluid mold material into the cavity of the mold during the course of an injection molding cycle.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0095] 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:
[0096] FIG. 1 is a schematic cross-sectional side 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;
[0097] 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;
[0098] FIG. 2 is a schematic diagram of one embodiment of the invention showing generically a hydraulically actuated valve pin in which at least one port of the actuator is connected to a flow restrictor so as to restrict the flow of hydraulic drive fluid and slow the opening of the valve pin by a selected lessening of pin opening velocity by use of a controller interconnected to the flow restrictor, the controller enabling the user to select a percentage of predetermined full open position velocity that the hydraulic drive supply to the actuator normally operates at full open velocity drive fluid pressure;
[0099] FIGS. 2A, 2B are schematic cross-sectional views of the hydraulic valves and restrictors used in the system of FIG. 1 according to the invention;
[0100] 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;
[0101] 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;
[0102] FIGS. 5A-5D are a series of plots of pin velocity versus position each plot representing a different example of the opening of a gate lateral to a central gate via continuous upstream withdrawal of a valve pin at one rate or set of rates over an initial flow path RP and at another higher rate or set of rates 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.
[0103] 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;
[0104] 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,
[0105] FIGS. 7-9 are examples of displays that can be displayed on a user interface, the user interface being interconnected to a master computer controller as shown and described with reference to the FIGS. 1, 3 embodiments;
[0106] FIG. 10 is a side cross-sectional view of a shaftless motor for use as an alternative actuator for flow control mechanism in accordance with the invention, the motor having an axially movable screw for driving the flow controller
DETAILED DESCRIPTION
[0107] FIG. 1 shows a system 10 with a central nozzle 22 feeding molten material from an injection molding machine 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.
[0108] 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 100a in the cavity just before 100b 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 100b to travel to a position 100p just past the positions 34, 36. Once the fluid material has travelled just past 100p of 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.
[0109] 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.
[0110] When the lateral gates 34, 36 are opened and fluid material NM is allowed to first enter the mold cavity into the stream 102p that has been injected from center nozzle 22 past gates 34, 36, the two streams NM and 102p 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, a visible line or defect in the mixing of the two streams 102p 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 102p, the appearance of a visible line or defect in the final molded product can be reduced or eliminated.
[0111] The rate or velocity of upstream withdrawal of pins 1041, 1042 starting from the closed position is controlled via controller 16, FIGS. 1, 2 which controls the rate and direction of flow of hydraulic fluid from the drive system 700 to the actuators 940, 941, 942. 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.
[0112] As shown in FIGS. 2A, 2B, a supply of hydraulic fluid 14 is fed first through a directional control valve 750 mechanism that switches the hydraulic fluid flow to the actuator cylinders in either of two directions: fluid out to withdraw the pin upstream, FIG. 2A, and fluid in to drive the pin downstream, FIG. 2B. At the beginning of an injection cycle the gate of a lateral valve 34, 36 is closed and the hydraulic system is in the directional configuration of FIG. 2B. When a cycle is started, the directional configuration of the directional valve 750 of the hydraulic system 700 is switched by controller 16 to the configuration of FIG. 2A. The hydraulic system includes a flow restriction valve 600 that can vary the rate of flow of hydraulic fluid to the actuator 941 under the control of the controller 16 to vary the rate of travel, upstream or downstream of the piston of the actuator 941 which in turn controls the direction and rate of travel of pin 1041. Although not shown in FIGS. 2A, 2B, the hydraulic system 700 controls the direction and rate of travel of the pistons of actuators 940 and 942 in a manner similar to the manner of control of actuator 941 via the connections shown in FIG. 1.
[0113] The user programs controller 16 via data inputs on a user interface to instruct the hydraulic system 700 to drive pins 1041, 1042 at an upstream velocity of travel that is reduced relative to a maximum velocity that the hydraulic system can drive the pins 1041, 1042 to travel. As described below, such reduced pin withdrawal rate or velocity is 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. 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.
[0114] FIG. 1 shows position sensors 950, 951, 952 for sensing the position of the actuator cylinders 940, 941, 942 and their associated valve pins (such as 1040, 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.
[0115] 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.
[0116] 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.
[0117] 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.
[0118] The velocity of withdrawal of the valve pins 1041, 1042 is determined by regulation of the flow of hydraulic drive fluid that is pumped from a supply 14 to the actuators 941, 942 through a flow restrictor valve 600, FIGS. 1, 2, 2A, 2B. When the flow restrictor valve 600 is completely open, namely 100% open, allowing maximum flow of the pressurized hydraulic fluid to the actuator cylinders, the valve pins 1041, 1042 are driven at a maximum upstream travel velocity. According to the invention, the degree of openness of the flow restrictor valve is adjusted in response to sensing of position of a suitable component such as an actuator 941, 942 or associated valve pin to less than 100% open. 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 selected period of time. At the end of the travel or length of path RP, RP2, a position sensor signals the controller 16, the controller 16 determines that the end COP, COP2 has been reached and the valve 600 is opened to a higher velocity, typically to its 100% open position to allow the actuator pistons and the valve pins 1041, 1042 to be driven at maximum upstream velocity FOV in order to reduce the cycle time of the injection cycle.
[0119] 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 via a source of electrical power that controllably drives an electromechanical mechanism 602 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 602 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 travel of the pins 1041, 1042 is proportional to the amount or degree of electrical energy that is input to the electro-mechanism 602 drives of valves 600. The electro-mechanism 602 that is selected for driving the valve 600 establishes in the first instance the maximum amount of electrical energy or power (such as voltage or current) that is required to open the valve to its 100% open position. A control for setting the amount or degree of electrical energy or power input to the motor is contained within the controller 16. Controller 16 includes an interface that enables the user to input any selected fraction or percentage of the maximum electrical energy or power needed to adjust the valve 600 to less than 100% open for beginning from the gate closed position of the valve pins 1041, 1042 and their associated actuators 941, 942. Thus the user selects 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.
[0120] 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.
[0121] As shown by the series of examples of programs illustrated in FIGS. 5A-5D one or more reduced pin velocities can be selected and the pin driven by restricted hydraulic fluid flow (or by reduced velocity drive by an electric actuator) between the gate closed (X and Y axis zero position) and the final intermediate upstream open gate position (4 mm for example in the FIG. 5A example, 5 mm in the FIG. 5B example) at which point the controller 16 in response to position sensing instructs the drive system to drive pin 1041, 1042 to travel upstream at a higher, typically maximum, upstream travel velocity (as shown, 100 mm/sec in the FIGS. 5A-5D examples). 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.
[0122] FIGS. 5B-5D illustrate a variety of alternative examples for driving the pin 1041, 1042 at reduced velocities for various durations of time. For example as shown in FIG. 5B, the pin is driven for 0.02 seconds at 25 mm/sec, then for 0.06 seconds at 75 mm/sec and then allowed to go to full valve open velocity shown as 100 mm/sec. Full valve open or maximum velocity is typically determined by the nature of hydraulic (or pneumatic) valve or motor drive system that drives the valve pin. In the case of a hydraulic (or pneumatic) system the maximum velocity that the system is capable of implementing is determined by the nature, design and size of the pumps, the fluid delivery channels, the actuator, the drive fluid (liquid or gas), the restrictor valves and the like.
[0123] As shown in FIGS. 5A-5D, the velocity of the valve pin when the pin reaches the end of the reduced velocity period, the valve 600 can be instructed to assume the full open position essentially instantaneously or alternatively can be instructed to take a more gradual approach up, between 0.08 and 0.12 seconds, to the maximum valve openness as shown in FIG. 5D. In all cases the controller 16 instructs the valve pin 1041, 1042 to travel continuously upstream rather than follow a profile where the pin might travel in a downstream direction during the course of the injection cycle. Most preferably, the actuator, valve pin, valves and fluid drive system are adapted to move the valve pin between a gate closed position and a maximum upstream travel position that defines an end of stroke position for the actuator and the valve pin. Most preferably the valve pin is moved at the maximum velocity at one or more times or positions over the course of upstream travel of the valve pin past the upstream gate open position. Alternatively to the hydraulic system depicted and described, a pneumatic or gas driven system can be used and implemented in the same manner as described above for a hydraulic system.
[0124] 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 FIGS. 5A-5C).
[0125] 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), FIGS. 5A-5D, 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 FIGS. 5A, 5B, 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.
[0126] 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 4B, 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 FIGS. 5A, 5B examples, the upstream FOP position is about 4 mm and 5 mm respectively upstream from the gate closed position. Other alternative upstream FOP positions are shown in FIGS. 5C, 5D.
[0127] 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.
[0128] In the FIGS. 5A-5D examples, 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.
[0129] 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.
[0130] The controller 16 includes a processor, memory, user interface and circuitry and/or instructions that receive and execute the user inputs of percentage of maximum valve open or percentage of maximum voltage or current input to the motor drive for opening and closing the restriction valve, time duration for driving the valve pin at the selected valve openings and reduced velocities.
[0131] 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 sensor of 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, RP2, RP3 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 130a with trip mechanism 133 that physically engages with the piston surface 223a when the piston 223 reaches the position of the trip mechanism 133. The FIG. 6D embodiment shows the use of two separate position switches 130a, 130aa having sequentially spaced trips 133aa and 133aaa that report the difference in time or distance between each trip engaging surface 223a 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 130a and then tripping the next 130aa. In each embodiment the position switch can signal the controller 16 when the valve pin 1041, 1042 has travelled to one or more selected intermediate upstream gate open positions between GC and RP, RP2 or RP3 so that the velocity of the pin can be adjusted to the selected or predetermined velocities determined by the user. 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.
[0132] In alternative embodiments the controller can include a processor and instructions that receive the pin position information and signals from the position sensor and calculate 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, RP2, RP3 path length and/or beyond. Typically such calculations of velocity are continuous throughout the cycle. In such an embodiment, the calculated pin velocity is constantly compared to a predetermined target profile of pin velocities and the velocity of the pin is adjusted in real time by the controller 16 to conform to the profile. In this embodiment as in all previously described embodiments, the pin is moved continuously upstream at all times between the gate closed position and all positions upstream of the gate closed 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.
[0133] As discussed above, control over the velocity of pin movement in an embodiment where the pin is driven by a hydraulic or pneumatic actuator is typically accomplished by controlling the degree of openness of the fluid restriction valve 600, control over velocity and drive rate or position of valve 600 being the same functions in terms of the instructions, microprocessor design or computer software that carries out instructing and implementing the velocity or drive rate adjustment to the valve pin or actuator. Where the position sensing system senses the position of the pin or other component multiple times throughout the course of the pin or other component movement, and real time velocity can be calculated by the controller 16, a program or instructions can be alternatively used to receive a velocity data input by the user to the controller 16 as the variable to be stored and processed instead of a predetermined voltage or current input Where an actuator that comprises an electric motor is used as the drive mechanism for moving the valve pin 1041, 1042 instead of a fluid driven actuator, the controller 16 can similarly be programmed to receive and process velocity data input as a variable for controlling the velocity or rate of drive of the electric actuator.
[0134] Other sensed conditions can be used which relate to melt flow rate other than pressure. For example, the position of a melt flow controller or valve pin or the load on the valve pin could be the sensed condition. If so, a position sensor or load sensor, respectively, could be used to feed back the sensed condition to the PID controller.
[0135] The system can be implemented using a user interface 214, FIGS. 7a-7b in which each target profile can be stored, displayed and sent as an input to the algorithm to be executed by the computer/controller 20. Alternatively the profile data can be input to and stored directly in the computer without the interface.
[0136] FIGS. 7a, 7b show one example of pressure versus injection cycle time graphs (235, 237) of the pressure detected by the two pressure transducers 60a, 80a associated with the two channels 167, 169. The graphs of FIGS. 7a, 7b are generated and/or displayed on the user interface 214 so that a user can observe the tracking of the actual pressure during an actual injection cycle versus the target pressure during the course of an actual injection cycle in real time, or after the cycle is complete. The two different graphs of FIGS. 9a and 9b show two independent target pressure profiles (desired) emulated by the two channels 167, 169. Different target profiles may be desirable to uniformly fill different sized mold cavities associated with each channel that is associated with actuators 50a-d, or to uniformly fill different sized sections of a single cavity. Profiles such as these can be generated with respect to any embodiments of the invention.
[0137] Following is a list of exemplary flow rate indicative parameters that a sensor can be used to detect for use in the invention: [0138] position of a flow controlling valve pin or actuator cylinder; [0139] force or pressure exerted on or by a flow controlling valve pin, actuator cylinder, ram, screw or motor; [0140] energy or power used to operate a flow controlling actuator, ram, motor or the like; [0141] flow rate recorded by a mechanical, optical or electronic sensing flowmeter; [0142] flow volume injected over time by a machine ram/screw; [0143] velocity of movement of a flow controlling component such as valve pin, alternative ram, plunger, rotary valve or the like.
[0144] As described with respect to the FIGS. 7a, 7b, 8, 9 profiles of fluid pressure data, a similar profile of data for any of the above variables over the time of an injection cycle may be obtained by trial and error running of an injection molding apparatus and then used as a target profile to be emulated by an algorithm to control the movement of a melt flow controller during an injection cycle.
[0145] FIG. 10 shows an example of an electrically powered motor which may be used as an actuator 301, in place of a fluid driven mechanism (such as 30, 40, 30a, 40a, FIGS. 1, 3) for driving a valve pin or rotary valve or other nozzle flow control mechanism. In the embodiment shown in FIG. 10 a shaftless motor 300a mounted in housing 302 has a center ball nut 304 in which a screw 306 is screwably received for controlled reciprocal driving 308 of the screw 308a along axis XX. Other motors which have a fixed shaft in place of the screw may also be employed as described more fully in U.S. application Ser. No. 09/187,974, the disclosure of which is incorporated herein by reference. As shown in the FIG. 12 embodiment the nut 304 is rigidly interconnected to magnet 310c and mounting components 310a, 310b which are in turn fixedly mounted on the inner race of upper rotational bearing 312 and lower rotational bearing 314 for rotation of the nut 304 relative to housing 302 which is fixedly interconnected to the manifold 15a of the injection molding machine. The axially driven screw 308a is fixedly interconnected to valve pin 41 which reciprocates 308 along axis X together with screw 308a as it is driven. As described more fully below, pin 41 is preferably readily detachably interconnected to the moving component of the particular actuator being used, in this case screw 308a. In the FIG. 22 embodiment, the head 41a of pin 41p is slidably received within a complementary lateral slot 321 provided in interconnecting component 320a. The housing 302 may be readily detached from manifold 15a by unscrewing bolts 324 and lifting the housing 302 and sliding the pin head 41a out of slot 321 thus making the pin readily accessible for replacement. As can be readily imagined other motors may be employed which are suitable for the particular flow control mechanism which is disposed in the flow channel of the manifold or nozzle, e.g. valve pin or rotary valve. For example, motors such as a motor having an axially fixed shaft having a threaded end which rotates together with the other rotating components of the actuator 301 and is screwably received in a complementary threaded nut bore in pin interconnecting component 320, or a motor having an axially fixed shaft which is otherwise screwably interconnected to the valve pin or rotary valve may be employed.
[0146] Controlled rotation 318 of screw 308a, FIG. 10 is achieved by interconnection of the motor 300a to a motor controller 316 which is in turn interconnected to the CPU, the algorithm of which (including PID controllers) controls the on/off input of electrical energy to the motor 300a, in addition to the direction and speed of rotation 318 and the timing of all of the foregoing. Motor controller 316 may comprise any conventional motor control mechanism(s) which are suitable for the particular motor selected. Typical motor controllers include an interface 316a for processing/interpreting signals received from the computer 20 similar to the interface 214, 300 described with reference to FIGS. 7a, 7b, 8, 9; and, the motor controllers typically comprise a voltage, current, power or other regulator receiving the processed/interpreted signals from interface 316a that regulates the speed of rotation of the motor 300 according to the instruction signals received from computer 20.
