Reduced velocity control based on sensed system condition

An injection molding system comprised of:

BACKGROUND OF THE INVENTION

Injection molding systems using multiple sensors for sensing the position of multiple valve pins or actuators or the pressure of injection material within multiple nozzles or at multiple gates to follow a non-adaptive profile of pressure or non-adaptive profile of pin position over the course of sequential injection molding cycles have been developed. The present invention overcomes limitations in such systems as described for example in WO2012074879(A1) and U.S. Pat. No. 6,464,909.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided an injection molding system comprised of:

an injection machine having a barrel and a screw for injecting an injection fluid to one or more downstream gates of one or more cavities of one or more molds during a first injection cycle and during a second injection cycle following the first injection cycle,

a distribution manifold for receiving the molten injection fluid from the barrel and distributing the injection fluid through one or more fluid delivery channels in the manifold that deliver the injection fluid to the one or more downstream fluid passages that mate with corresponding ones of the one or downstream gates to the one or more mold cavities,

a valve associated with each downstream gate, each valve comprising an actuator interconnected to and reciprocally driving a corresponding valve pin at one or more selectable upstream travel velocities that include a maximum upstream travel velocity, the valve pins being driven between a gate closed position and a selected maximum upstream gate open position defining a complete upstream path of travel for each injection cycle,

a sensor adapted to sense pressure of the injection fluid in the barrel or in an inlet that delivers injection fluid from the barrel to the manifold,

a controller to which the sensor sends a signal indicative of the sensed pressure,

the controller receiving the signal and including instructions that use the signal as a control value that controls each valve pin to be driven, during the second injection cycle, through an initial upstream path of travel beginning from the closed position through at least a portion of the complete upstream path of travel at one or more initial reduced upstream travel velocities during the second injection cycle that are less than the maximum upstream travel velocity,

the instructions further using the control value as a variable in an algorithm that establishes an instruction value for the one or more initial reduced upstream velocities that operates to drive the one or more valve pins to effect a rate of flow of injection fluid through each gate corresponding to the one or more valve pins during the second injection cycle that is either reduced or is substantially constant relative to the rate of flow of injection fluid during the first injection cycle over at least the initial upstream path of travel of the one or more valve pins.

The controller preferably uses the signal sent by the sensor as a control value that controls each actuator to drive a corresponding valve pin, during a third injection or other subsequent cycle following the second injection cycle, through an initial upstream path of travel beginning from the closed position through at least a portion of the complete upstream path of travel at one or more initial reduced upstream travel velocities during the third or other subsequent injection cycle that are less than the maximum upstream travel velocity, the instructions further using the control value as a variable in an algorithm that establishes an instruction value for the one or more initial reduced upstream velocities that operates to drive the one or more valve pins to effect a rate of flow of injection fluid through each gate corresponding to the one or more valve pins during the third or other subsequent injection cycle that is either reduced or is substantially constant relative to the rate of flow of injection fluid during the second injection cycle over at least the initial upstream path of travel of the one or more valve pins.

The sensor is typically adapted to sense one or more conditions selected from the group of:

pressure of the injection fluid in the barrel or in the inlet,

speed or position of the screw,

pressure of the injection fluid in the one or more fluid delivery channels in the manifold,

pressure in a cavity of one or more of the molds,

wherein the sensor sends a signal indicative of the one or more sensed conditions to the controller, and,

the controller receives and uses the signal as the control value.

The instructions can instruct the actuator to drive the pin continuously upstream throughout the complete upstream path of travel.

The controller can receive and the instruction can use the control value in real time in a closed loop over the course of travel of the one or more valve pins over at least a portion of the complete path of upstream travel, the instructions directing the one or more valve pins to either follow a predetermined profile of pressure or pin position or velocity or to calculate a pin position or velocity and drive the pin at or to the calculated position or velocity in real time based on the control value.

In another aspect of the invention there is provided a method of injecting an injection fluid into one or more cavities of one or more molds, comprising:

operating an injection molding system as described immediately above to inject the injection fluid into the one or more cavities, and

forming a part from the injection fluid injected into the one or more cavities.

In another aspect of the invention there is provided an injection molding system comprised of:

an injection machine having a barrel and a screw for injecting an injection fluid,

a distribution manifold for receiving the injection fluid from the barrel and distributing the injection fluid through one or more fluid delivery channels in the manifold that deliver the injection fluid to one or more downstream fluid passages that mate with corresponding one or more downstream gates to corresponding one or more mold cavities,

a valve associated with a corresponding one of one or more downstream gates, each valve comprising an actuator interconnected to and reciprocally driving a corresponding valve pin at one or more selectable upstream velocities including a maximum upstream velocity, the valve pin being driven between a gate closed position and a selected maximum upstream gate open position defining a complete upstream path of travel,

a sensor adapted to sense and generate a signal indicative of pressure of the injection fluid in the barrel or an inlet that delivers injection fluid from the barrel to the manifold,

the controller receiving the signal generated from the sensor and including instructions that use the signal as a control value to adjust, during the course of an injection cycle, positioning or velocity of one or more of the valve pins such that the rate of flow of injection fluid into a corresponding one or more of the cavities is controlled, during the course of the injection cycle, based on the control value.

The instructions typically use the signal as a control value to drive one or more of the valve pins through an initial upstream path of travel beginning from the closed position through at least a portion of the complete upstream path of travel at one or more initial reduced upstream travel velocities that are less than the maximum upstream travel velocity.

Preferably the system is operable to carry out a first injection cycle and a second injection cycle following the first injection cycle, the instructions using the signal as a control value that controls one or more valve pins to be driven, during the second injection cycle, through an initial upstream path of travel beginning from the closed position through at least a portion of the complete upstream path of travel at one or more initial reduced upstream travel velocities during the second injection cycle that are less than the maximum upstream travel velocity,

the instructions further using the control value as a variable in an algorithm that establishes an instruction value for the one or more initial reduced upstream velocities that operates to drive the one or more valve pins to effect a rate of flow of injection fluid through each gate corresponding to the one or more valve pins during the second injection cycle that is either reduced or is substantially constant relative to the rate of flow of injection fluid during the first injection cycle over at least the initial upstream path of travel of the one or more valve pins.

The instructions can instruct the actuator to drive the pin continuously upstream throughout the complete upstream path of travel.

The controller can receive and the instructions can use the control value in real time in a closed loop over the course of travel of the one or more valve pins over at least a portion of the complete path of upstream travel, the instructions directing the one or more valve pins to either follow a predetermined profile of pressure or pin position or velocity or to calculate a pin position or velocity and drive the pin at or to the calculated position or velocity in real time based on the control value.

In another aspect of the invention there is provided a method of injecting an injection fluid into one or more cavities of one or more molds, comprising: operating an injection molding system as described immediately above to inject the injection fluid into the one or more cavities, and forming a part from the injection fluid injected into the one or more cavities.

In another aspect of the invention there is provided an injection molding system comprised of:

an injection machine having a barrel and a screw for injecting an injection fluid,

a distribution manifold for receiving the molten injection fluid from the barrel and distributing the injection fluid through one or more fluid delivery channels in the manifold that deliver the injection fluid to one or more downstream fluid passages that mate with corresponding downstream gates to one or more mold cavities,

a valve associated with each downstream gate, each valve comprising an actuator interconnected to and reciprocally driving a corresponding valve pin at one or more selectable upstream velocities including a maximum upstream velocity, the pin being driven between a gate closed position and a selected maximum upstream gate open position defining a complete upstream path of travel,

a controller that receives a signal from a sensor adapted to sense and generate a signal indicative of a condition selected from the group of:pressure of the injection fluid in the barrel or an inlet that delivers injection fluid from the barrel to the manifold,speed or position of the screw,pressure of the injection fluid in the one or more fluid delivery channels in the manifold,

the controller including instructions that use only the signal indicative of the selected condition as a control value that controls one or more valve pins to be driven through an initial upstream path of travel during an injection cycle beginning from the closed position through at least a portion of the complete upstream path of travel at one or more initial reduced upstream travel velocities during that are less than the maximum upstream travel velocity,

the instructions further using the control value as a variable in an algorithm that establishes an instruction value for the one or more initial reduced upstream velocities that operates to drive the one or more valve pins to effect a rate of flow of injection fluid through each gate corresponding to the one or more valve pins during the injection cycle that is reduced relative to a maximum rate of flow of injection fluid an injection cycle over at least the initial upstream path of travel of the one or more valve pins.

The instructions in such an apparatus can instruct the actuator to drive the valve pin at one or more reduced velocities that are less than the maximum upstream velocity that maintain pressure of the injection material travelling through the gate at a substantially constant pressure throughout the course of the complete upstream path of travel.

Such a system is typically operable to carry out a first injection cycle and a second injection cycle following the first injection cycle, the instructions using the signal as a control value that controls one or more valve pins to be driven, during the second injection cycle, through an initial upstream path of travel beginning from the closed position through at least a portion of the complete upstream path of travel at one or more initial reduced upstream travel velocities during the second injection cycle that are less than the maximum upstream travel velocity,

the instructions using the control value as a variable in an algorithm that establishes an instruction value for the one or more initial reduced upstream velocities that operates to drive the one or more valve pins to effect a rate of flow of injection fluid through each gate corresponding to the one or more valve pins during the second injection cycle that is either reduced or is substantially constant relative to the rate of flow of injection fluid during the first injection cycle over at least the initial upstream path of travel of the one or more valve pins.

The instructions can instruct the actuator to drive the pin continuously upstream throughout the complete upstream path of travel.

The controller can receive and the instructions can use the control value in real time in a closed loop over the course of travel of the one or more valve pins over at least a portion of the complete path of upstream travel, the instructions directing the one or more valve pins to either follow a predetermined profile of pressure or pin position or velocity or to calculate a pin position or velocity and drive the pin at or to the calculated position or velocity in real time based on the control value.

In another aspect of the invention there is provided a method of injecting an injection fluid into one or more cavities of one or more molds, comprising:

operating an injection molding system as described immediately above to inject the injection fluid into the one or more cavities, and

forming a part from the injection fluid injected into the one or more cavities.

In another aspect of the invention there is provided an injection molding system comprised of:

an injection machine having a barrel and a screw for generating and injecting molten injection material,

a distribution manifold for receiving the molten injection material from the injection machine and distributing the molten injection material through fluid delivery channels in the manifold to at least one fluid passages having a downstream gate,

a mold having a cavity communicating with the gate for receiving the injection fluid material from the manifold through the fluid passage,

a valve comprising an actuator interconnected to and reciprocally driving a pin at one or more selectable upstream velocities including a maximum upstream velocity, the pin being driven between a gate closed position and a selected maximum upstream gate open position defining a complete upstream path of travel,

a sensor mounted to the barrel and arranged such that the sensor senses the molten injection material disposed in the barrel upstream of the manifold,

the sensor sensing pressure and sending a signal representative of the pressure of the injection material in the barrel to a controller,

the controller receiving the signal, and having algorithm that includes instructions that use the signal to instruct the actuator to drive the valve pin through an initial upstream path of travel beginning from the closed position through at least a portion of the complete upstream path of travel at an initial reduced upstream velocity that is less than the maximum upstream velocity and that maintains pressure of the injection material travelling through the gate at a substantially steady or constant pressure during at least the course of travel of the pin through the initial upstream path of travel.

The instructions typically instruct the actuator to drive the valve pin at one or more reduced velocities that are less than the maximum upstream velocity that maintain pressure of the injection material travelling through the gate at a substantially constant pressure throughout the course of the complete upstream path of travel.

The instructions preferably instruct the actuator to drive the pin continuously upstream throughout the complete upstream path of travel.

In another aspect of the invention there is provided an injection molding system comprised of:

an injection machine having a barrel and a screw for generating and injecting molten injection material,

a distribution manifold for receiving the molten injection material from the injection machine and distributing the molten injection material through fluid delivery channels in the manifold to at least one fluid passages having a downstream gate,

a mold having a cavity communicating with the gate for receiving the injection fluid material from the manifold through the fluid passage,

a valve comprising an actuator interconnected to and reciprocally driving a pin at one or more selectable upstream velocities including a maximum upstream velocity, the pin being driven between a gate closed position and a selected maximum upstream gate open position defining a complete upstream path of travel,

a sensor mounted and arranged such that the sensor senses the molten injection material disposed in a fluid flow channel downstream of the barrel,

the sensor sensing pressure and sending a signal representative of the pressure of the injection material in the fluid flow channel,

the controller receiving the signal, and having algorithm that includes instructions that use the signal to instruct the actuator to drive the valve pin through an initial upstream path of travel beginning from the closed position through at least a portion of the complete upstream path of travel at an initial reduced upstream velocity that is less than the maximum upstream velocity and that maintains pressure of the injection material travelling through the gate at a substantially steady or constant pressure during at least the course of travel of the pin through the initial upstream path of travel.

The instructions preferably instruct the actuator to drive the valve pin at one or more reduced velocities that are less than the maximum upstream velocity that maintain pressure of the injection material travelling through the gate at a substantially constant pressure throughout the course of the complete upstream path of travel.

The instructions typically instruct the actuator to drive the pin continuously upstream throughout the complete upstream path of travel.

In another aspect of the invention there is provided an injection molding system comprised of:

an injection machine having a barrel and a screw for generating and injecting molten injection material,

a distribution manifold for receiving the molten injection material from the injection machine and distributing the molten injection material through fluid delivery channels in the manifold to at least one fluid passages having a downstream gate,

a mold having a cavity communicating with the gate for receiving the injection fluid material from the manifold through the fluid passage,

a valve comprising an actuator interconnected to and reciprocally driving a pin at one or more selectable upstream velocities including a maximum upstream velocity, the pin being driven between a gate closed position and a selected maximum upstream gate open position defining a complete upstream path of travel,

a sensor mounted and arranged such that the sensor senses the molten injection material disposed in a fluid flow passage or the mold cavity,

the sensor sending a signal representative of the pressure of the injection material in the fluid flow passage or the mold cavity,

the controller receiving the signal, and having algorithm that includes instructions that use the signal to instruct the actuator to drive the valve pin through an initial upstream path of travel beginning from the closed position through at least a portion of the complete upstream path of travel at an initial reduced upstream velocity that is less than the maximum upstream velocity and that maintains pressure of the injection material travelling through the gate at a substantially steady or constant pressure during at least the course of travel of the pin through the initial upstream path of travel.

The instructions typically instruct the actuator to drive the valve pin at one or more reduced velocities that are less than the maximum upstream velocity that maintain pressure of the injection material travelling through the gate at a substantially constant pressure throughout the course of the complete upstream path of travel.

The instructions preferably instruct the actuator to drive the pin continuously upstream throughout the complete upstream path of travel.

In another aspect of the invention there is provided an injection molding system comprised of:

an injection machine having a barrel and a screw for generating and injecting molten injection material,

a distribution manifold for receiving the molten injection material from the injection machine and distributing the molten injection material through fluid delivery channels in the manifold to at least one fluid passages having a downstream gate,

a mold having a cavity communicating with the gate for receiving the injection fluid material from the manifold through the fluid passage,

a valve comprising an actuator interconnected to and reciprocally driving a pin at one or more selectable upstream velocities including a maximum upstream velocity, the pin being driven between a gate closed position and a selected maximum upstream gate open position defining a complete upstream path of travel,

a sensor mounted to the barrel and arranged such that the sensor senses the molten injection material disposed in the barrel upstream of the manifold,

the sensor sending a signal representative of the pressure of the injection material in the barrel to a controller,

the controller receiving the signal, and having an algorithm that includes instructions that use the signal to instruct the screw to drive the injection material at an increased pressure or rate that maintains pressure of the injection material travelling through the gate at a substantially steady or constant pressure during at least the course of travel of the pin through the initial upstream path of travel.

In another aspect of the invention there is provided an injection molding system comprised of:

an injection machine having a barrel and a screw for generating and injecting molten injection material,

a distribution manifold for receiving the molten injection material from the injection machine and distributing the molten injection material through fluid delivery channels in the manifold to at least one fluid passages having a downstream gate,

a mold having a cavity communicating with the gate for receiving the injection fluid material from the manifold through the fluid passage,

a valve comprising an actuator interconnected to and reciprocally driving a pin at one or more selectable upstream velocities including a maximum upstream velocity, the pin being driven between a gate closed position and a selected maximum upstream gate open position defining a complete upstream path of travel,

a sensor mounted to the barrel and arranged such that the sensor senses the molten injection material disposed in the system,

the sensor sending a signal representative of the pressure of the injection material to a controller,

the controller receiving the signal, and having an algorithm that includes instructions that use the signal to instruct the screw to drive the injection material at an increased pressure or rate that maintains pressure of the injection material travelling through the gate at a substantially steady or constant pressure during at least the course of travel of the pin through the initial upstream path of travel.

In another aspect of the invention there is provided a method of controlling injection of molten injection material in an injection molding system comprised of: an injection machine having a barrel and a screw for generating and injecting molten injection material, a distribution manifold for receiving the molten injection material from the injection machine and distributing the molten injection material through fluid delivery channels in the manifold to at least one fluid passages having a downstream gate, a mold having a cavity communicating with the gate for receiving the injection fluid material from the manifold through the fluid passage and a valve comprising an actuator interconnected to and reciprocally driving a pin at one or more selectable upstream velocities including a maximum upstream velocity, the pin being driven between a gate closed position and a selected maximum upstream gate open position defining a complete upstream path of travel, the method comprising:

mounting and arranging a sensor such that the sensor senses the molten injection material disposed in the barrel upstream of the manifold,

the sensor sensing pressure and generating a signal representative of the pressure of the injection material in the barrel,

instructing the actuator according to an algorithm that uses the signal to drive the valve pin through an initial upstream path of travel beginning from the closed position through at least a portion of the complete upstream path of travel at an initial reduced upstream velocity that is less than the maximum upstream velocity and that maintains pressure of the injection material travelling through the gate at a substantially steady or constant pressure during at least the course of travel of the pin through the initial upstream path of travel.

Such a method can further comprise driving the pin continuously upstream throughout entire course of the complete upstream path of travel.

In another aspect of the invention there is provided a method of controlling injection of molten injection material in an injection molding system comprised of: an injection machine having a barrel and a screw for generating and injecting molten injection material, a distribution manifold for receiving the molten injection material from the injection machine and distributing the molten injection material through fluid delivery channels in the manifold to at least one fluid passages having a downstream gate, a mold having a cavity communicating with the gate for receiving the injection fluid material from the manifold through the fluid passage and a valve comprising an actuator interconnected to and reciprocally driving a pin at one or more selectable upstream velocities including a maximum upstream velocity, the pin being driven between a gate closed position and a selected maximum upstream gate open position defining a complete upstream path of travel, the method comprising:

mounting and arranging a sensor such that the sensor senses the molten injection material disposed in system,

the sensor sensing pressure and generating a signal representative of the pressure of the injection material,

instructing the actuator according to an algorithm that uses the signal to drive the valve pin through an initial upstream path of travel beginning from the closed position through at least a portion of the complete upstream path of travel at an initial reduced upstream velocity that is less than the maximum upstream velocity and that maintains pressure of the injection material travelling through the gate at a substantially steady or constant pressure during at least the course of travel of the pin through the initial upstream path of travel.

Such a method can further comprise driving the pin continuously upstream throughout entire course of the complete upstream path of travel.

DETAILED DESCRIPTION

FIG. 1shows one system embodiment10of the invention comprised of an injection machine15that feeds meltable injection material that is converted from solid form17into molten or liquid flowing material form18within the barrel19of the machine15by a screw16. The screw16is controllably rotated at a selected rate such that the helical threads14of the screw16drive the molten material16downstream under a controlled pressure into a fluid distribution channel65of a hotrunner or manifold60. The fluid distribution channel65can commonly feed into the downstream flow passage(s)115of the injection nozzle(s)110of one or more of multiple valve gates or valves11,11a,11b,11c. In the example depicted inFIG. 1four valves or valve gates11,11a,11b,11care shown. More or less than four (4) valves can be employed in systems according to the invention. A single valve11can be employed, although multiple valves are typically employed and controlled.

Each valve11,11a,11b,11cis comprised of a downstream-most mounted nozzle110. Each nozzle110of each valve11,11a,11b,11croutes the molten fluid18that is received from a single common source such as the barrel19a,19, or an inlet19bthat interconnects the barrel19ato the manifold or from the common manifold channel65through a nozzle passage115to and ultimately through a gate85of the nozzle110of each valve11,11a,11b,11cto a single cavity80of a mold70. As shown, each of the multiple valves11,11a,11b,11ccould inject into the cavity80of a single mold70(typically in a cascade or sequential manner during the course of a single injection cycle). Or, one or more of the multiple valves could inject into the cavities of two or more separate molds70,72during the course of a single injection cycle.

The system10preferably employs a one or more detectors or sensors90or90aor90bor90cthat senses or detect a single property (typically pressure or a condition that is indicative of pressure) of the injection fluid18that is located in a single discrete locus (such as in the barrel19,19aor inlet19bor common channel65) that is indicative of the flow rate of the injection fluid to and through each of the valves11,11a,11b,11cor their associated nozzle passages115or their associated gates85. As shown, one locus and property that can be detected by a sensor such as detector90bthat is indicative of the fluid flow to or through each valve11,11a,11b,11cis position or speed of rotation of screw16. Another discrete locus and property that can be sensed and input to the controller200is the injection fluid18and its pressure located in the barrel cavity19awhich can be sensed by detector90at the discrete locus19awithin the barrel19as shown inFIG. 1. Another discrete locus at which a property of the injection fluid18can be detected is a locus within a common fluid flow channel such as manifold flow channel65that feeds all of the multiple valves11,11a,11b,11c. Another discrete locus at which a property of the injection fluid18can be sensed is within the passage of an inlet19bthat connects the output of the barrel19to the input of the manifold60.

As shown inFIG. 1, the pressure of the fluid18within barrel passage19aor inlet19bcan be detected by sensor or detector90and a signal95indicative of the pressure is sent to controller200. The pressure of fluid18within common manifold fluid flow channel65is sensed by sensor90aand a signal95aindicative of the pressure is sent to controller200. The speed or position of screw16is sensed by sensor90band a signal95bis sent to controller200. The signal95,95a,95bthat is sent to controller200is typically a continuous real time signal indicative of the sensed property (pressure or speed or position or the like) that occurs continuously over a portion or the entirety of the upstream travel path of an injection cycle, preferably over at least the initial upstream travel portion of a valve pin112beginning from a gate closed position to a position intermediate fully closed and fully upstream or open.

The controller200receives a signal95,95a,95band includes instructions that use the signal95,95a,95bas a control value that controls one or more valve pins112of one or more valves11,11a,11b,11csuch that the one or more valve pins112are driven through an initial upstream path of travel beginning from the gate closed position through at least a portion of a complete upstream path of travel at one or more initial reduced upstream travel velocities that are less than a maximum upstream travel velocity.

Alternatively, the controller200can be loaded with a predetermined preferred profile of pressure, pin velocity or screw speed that provides a predetermined ideal rate of fluid flow through a gate over the course of an injection cycle that corresponds to a predetermined profile of injection fluid pressure, velocity or the screw position or screw speed over the course of an injection cycle. The controller200can be provided with instructions that calculate, in a closed loop control manner, a value in real time that is indicative of real time pressure, velocity or screw speed that is based on real time receipt of a signal95,95a,95b. The controller200can then be provided with instructions that compare the calculated values based on the real time closed loop receipt of a signal95,95a,95bto the predetermined profile and instantaneously instruct one or more actuators of one or more valves11,11a,11b,11cto adjust the position or movement of a corresponding valve pin112or adjust the speed of the screw16to attempt to match the real time calculated value of the injection fluid pressure, velocity or screw speed of the predetermined profile. A generic protocol for comparing and matching data contained in a predetermined profile is described for example in U.S. Pat. No. 6,464,909. Such a predetermined profile can be established by performance in advance of trial and error runs of injection cycles the results of which determine the pressure, velocity or screw speed profile over an injection cycle that produces the most preferred quality or kind of part in a mold cavity80.

In another alternative control protocol, the predetermined profile of fluid pressure, velocity or screw speed can be established by user estimation or by instructions that automatically produce an improved profile based on manipulation of the data of a prior recorded profile according to a predetermined algorithm. For example, where a prior recorded profile of barrel pressure data from a first injection cycle exhibits sudden or severe dips in pressure over certain portions of the injection cycle, an improved profile can be generated by the controller200according to an algorithm that operates to reduce or eliminate the dips in pressure in the profile of the first injection cycle. The automatically adjusted and improved profile can then be used in a subsequent injection cycle. The controller200can thus execute the improved profile by controlling the positioning of the pin112in the subsequent injection cycle to attempt to follow the improved profile based on receipt by the controller200in real time of the signal95during the real time course of the subsequent injection cycle.

The variable or control value that is preferably used in an algorithm according to the invention, is generated by sensing a property of the system in a single discrete locus that is indicative of or common to the rate of fluid flow through all of multiple or plurality of nozzle passages115of all of multiple or plurality of valves11,11a,11b,11cin a flow system10. Using a sensed property from a single discrete locus of the system, the algorithm can be programmed to control the valve pin withdrawal velocity and thus the rate of fluid flow through the nozzle passages115and gates85of all of the multiplicity of valves11,11a,11b,11c.

FIG. 1illustrates the components of valve11in detail. For ease of explanation, each valve11a,11b,11cis typically comprised of the same components as described with reference to valve11, each valve being commonly fed by the injection fluid18flowing from barrel19and further flowing through downstream manifold channel65. Manifold channel65is shown and referred to as one example of a common fluid flow channel. Any channel that commonly feeds all of the multiple valves11,11a,11b,11ccould be employed for detecting a property of the injection fluid including a tube or pipe that interconnects the fluid output of the barrel19with the fluid input to flow channels disposed in the manifold60.

As shown, the distal end of nozzle110has a gate85that is controllably openable and closeable by a valve pin112to stop and start the flow of material18through gate85. Such controlled gate opening and closing is effected by controlled reciprocal upstream and downstream movement A of valve pin112that is controllably driven by a pneumatic actuator30that is in turn controllably driven most preferably by a fast acting linear force motor or valve20. The downstream distal tip end of the valve pin112initially closes the gate85at the start of an injection cycle. When an injection cycle is initiated the valve pin112is withdrawn upstream opening the gate85and allowing the molten material18to flow through the gate85into the cavity80of the mold70. Users of such equipment typically operate the system to cause the pin112to be withdrawn at a maximum upstream velocity causing the molten material18to flow at the highest pressure and rate of flow into the cavity80and often causing noticeably visible lines or blemishes on the final molded part that is formed within the cavity. Each separate valve11,11a,11b,11ccan feed into a single cavity of a single mold or can each feed separately into separate cavities of separate molds (not shown for valves11a,11b,11c).

In order to reduce or eliminate the visibility of the lines or blemishes in the final molded part, a fast acting motor20that drives a valve can be employed and can be controllably instructed by electronic signals210,210a,210b,210cgenerated by an algorithm contained in an electronic controller200to withdraw the pins112of one or more of valves11,11a,11b,11cat an upstream withdrawal velocity that is reduced relative to the maximum velocity of withdrawal.

FIGS. 2 and 4shows a plot of the injection fluid pressure in the barrel19aor inlet19bversus time over the course of a first injection cycle where four valves,11,11a,11b,11cthat are initially all closed are sequentially opened over the course of the first injection cycle.FIG. 4shows a time analogous plot of the screw16speed and screw16position over the same course of time of the same first injection cycle.

With regard to the plots ofFIGS. 2, 4, each of the valves11,11a,11b,11cstart at a valve pin gate closed position and are withdrawn sequentially upstream to a travel position where the valve pin is in a fully upstream or maximum upstream position. As shown, at time zero of the injection cycle, the first valve11is initially opened (with all other valves11a,11b,11cremaining closed) and the screw16is simultaneously started up to begin rotating and thus increasing the pressure in barrel19a, inlet19bfrom an initial zero up to an intermediate local maximum or high peak pressure220a.

In the first injection cycle as shown inFIGS. 2, 4, at about time P1the second valve pin associated with the second valve11ais initially withdrawn from its associated gate at maximum upstream velocity causing the pressure220ain the barrel19ato suddenly drop down until the pressure in the barrel19areaches a low peak of220bat time D1. As shown inFIG. 4, between time P1and D1the screw speed increases because of the drop in fluid pressure and the constant amount of power driving the screw16. Between time P1and D1the screw speed continues to increase until eventually at about time D1the speed of the screw16has caught up with the dip in pressure to cause the pressure in barrel19aand inlet19bto begin to rise again. With the first and second valves11,11anow open at time D1and third and fourth valves11b,11cstill closed, the pressure continues to increase as the screw continues to inject injection fluid into the system until the pressure reaches a second high peak pressure230aat time P2when the pin associated with the third valve11bis opened from its associated gate and withdrawn at maximum velocity thus causing the pressure to again drop down to a low peak pressure230bat time D2. Similarly, between time P2and D2the screw speed continues to increase until eventually at about time D2the speed of the screw16has caught up with the dip in pressure to cause the pressure in barrel19aand inlet19bto begin to rise again. Now with the first and second and third valves11,11a,11bopen and valve11cstill closed, the pressure continues to increase beginning at time D2as the screw continues to inject injection fluid into the system until the pressure reaches a third high peak pressure240aat time P3at which time the pin associated with the fourth valve11cis withdrawn at maximum upstream velocity from its associated gate closed position thus causing the pressure to again drop down to a low peak pressure240bat time D3. At time D3with all four valves now open and the screw under constant power drive force, the pressure continues to rise from low peak240bup to a final constant or steady pressure250a.

During the first injection cycle, as shown inFIG. 4, between each of the high peak pressure times P1, P2, P3and low peak pressure times D1, D2, D3, the screw speed increases because of the fluid pressure drops the screw16is driven under a constant amount of power without algorithmic control of the screw speed.

In one aspect of the invention, the system10can achieve a relatively constant fluid pressure in the barrel19,19a(or the manifold channel65) over the course of an entire subsequent second or third or other injection cycle that follows a prior injection cycle such as the first injection cycle where pressure dips as described above have occurred on account of high velocity withdrawal of the valve pins from the gate closed positions.

FIG. 3shows a plot of barrel fluid pressure versus time that occurs on a second or third or other subsequent injection cycle that follows the first injection cycle plotted inFIGS. 2, 4using the controller200to control upstream pin withdrawal velocity. As shown inFIG. 3, the sudden dips in injection fluid pressure that occurred on the first injection cycle ofFIGS. 2, 4, (beginning at times P1, P2, P3) can be corrected for, starting with at least a second subsequent injection cycle,FIG. 3, by reducing the initial upstream withdrawal velocity of one or more of the valve pins112associated with one or more of the valves11,11a,11b,11cby a preselected reduction in initial upstream withdrawal velocity of the valve pins112that can be programmed into the instructions or by a real time calculated amount of reduction in upstream withdrawal velocity using a real time closed loop signal95,95a,95bor95cas a variable in an algorithm executed by controller200that calculates and executes pin withdrawal velocity in real time during the course of an injection cycle.

As shown inFIG. 3, beginning at time P1when the barrel pressure has reached a peak and the second valve11ais initially opened, the sensor90sends a pressure signal95(or sensors90a,90bsend signals95a,95b) to controller200that has a program with instructions that use the received pressure signal as a value in an algorithm that determines a reduced valve pin withdrawal speed for each of the valves11a,11band11cat the predetermined sequential valve opening times P1, P2, P3respectively. The calculated reduced valve pin withdrawal speeds are sent by controller200to one or more of the drive valves20. The calculated reduced valve pin withdrawal speeds are used by controller200to control the speed of upstream movement of the corresponding actuators30associated with each valve pin112associated with each of valves11a,11b,11c. The pressure signal95,95aor screw position or speed signal95bis preferably sent continuously during the second or other subsequent injection cycle to the controller200and most preferably continuously at least over that portion of the cycle where the valve pin112travels from the gate closed position to positions upstream of the gate where the distal tip ends112dof the valve pins112are positioned relative to the interior surface85sof the gates85such that the distal ends112doperate to slow or reduce the rate of flow injection fluid through the gates85by restricting the size of the fluid flow passage between the distal ends112dand the internal surfaces85sof the gates as described in PCT/US13/75064 filed Dec. 13, 2013 and international application PCT/US14/192210 filed Feb. 28, 2014 and international application PCT/US14/31000 filed Mar. 18, 2014, the disclosures of which are incorporated herein by reference in their entirety as if fully set forth herein.

In embodiments where the controller200controls all of the multiple valve gates11,11a,11b,11cduring an injection cycle, the controller200includes a pin sequence instruction that can instruct and execute the opening and upstream pin withdrawal velocity of each separate valve11,11a,11b,11cin any preselected timed sequence.

As shown inFIG. 3the ideal end result of the controller's instructions using a real time signal95,95a,95b,95cto adjust the upstream valve pin withdrawal velocity is to flatten the pressure plot out such that there are fewer or less pronounced dips in pressure of the injection fluid in the barrel19,19aor in the manifold channel65upon opening of one or more of the valves11,11a,11b,11cduring an injection cycle. Ideally, the pressure rises to a peak at time P1and remains substantially steady or constant310or close to steady320(smoothly rising relatively little) over the course of time between when the second valve gate11ais opened P1and the time D3shortly after the last valve gate11chas been opened.

FIG. 5shows another alternative plot of barrel pressure versus time with corresponding screw speed and screw position versus time for an injection cycle where the controller200controls the upstream withdrawal velocities of the one or more valve pins using a real time signal95,95a,95bor95cin an appropriate algorithm as described above.

The instructions included in the program preferably use the continuously received signal95,95a,95bto calculate in real time during the course of an injection cycle the withdrawal speed of the valve pins or actuators associated with one or more of the valves11,11a,11b,11cso as to substantially reduce or eliminate the dips in pressure that occur between times P1and D1or P2and D2or P3and D3as described with reference to a first or previous injection cycle. In a typical embodiment, the algorithm of the controller will calculate and execute a first partially reduced or modified withdrawal velocity for one or more of the valves on a second subsequent injection cycle and continue on a third or fourth or other subsequent injection cycle to calculate and execute further reduced or modified pin withdrawal velocities based on the degree of dips in barrel (or inlet or channel) pressure that may be detected at the predetermined valve opening times P1, P2, P3. Thus a system10according to the invention can be programmed to “self-adapt” on each subsequent injection cycle to reduce or eliminate dips in barrel pressure (or screw speed) in any one or more injection cycles where a dip in pressure or screw speed is detected by a sensor90,90a,90b.

In alternative embodiments, the pressure of the material18acan be measured by a sensor90amounted and arranged to sense injection fluid material flowing within a channel65disposed within the manifold60that commonly feeds all nozzles115. The pressure of the fluid material can alternatively be measured and sensed by a sensor90cmounted and arranged to sense the material disposed within the cavity80. In each embodiment, the sensors90,90a,90csend a signal representative of the sensed pressure to the controller200for use in the algorithm that controls the drive of the actuators to reduce the withdrawal velocity of one or more pins112.

The actuators typically comprise a pneumatic or hydraulic actuator or an electric actuator, the controller200being adapted to control the drive mechanism for each such kind of actuator. In the case of a pneumatically or hydraulically driven actuator, the drive mechanism is an electrically drivable mechanism interconnected to a fluid flow control valve similar to valve20. In the case of an electric actuator the drive mechanism is typically an electric motor that is controllably drivable by an electronic controller200.

Thus algorithm in the controller200knows when and for how long to reduce the upstream withdrawal velocity based on the pressure or screw speed signal received from a sensor as a drop or increase in pressure of the material18or an increase in screw speed corresponds to an increase in material flow rate at the gate85area.

In order to minimize, reduce or eliminate artifacts or blemishes in the final molded part in the cavity80, the pressure of the injection material18,18ais preferably maintained at a substantially constant or steady pressure particularly when the valve pins112are initially opened at the start of a cycle.