WO2016089962A1

WO2016089962A1 - Valve stem control system

Info

Publication number: WO2016089962A1
Application number: PCT/US2015/063374
Authority: WO
Inventors: Patrice Fabien Dezon-Gaillard
Original assignee: Husky Injection Molding Systems Ltd.
Priority date: 2014-12-05
Filing date: 2015-12-02
Publication date: 2016-06-09

Abstract

Disclosed is a valve stem control system, comprising a stem actuation plate connected to a plurality of valve stems, the stem actuation plate controlled by a pneumatic pressure; a sensor to measure a characteristic associated with the stem actuation plate; a proportional valve for controlling a supply of air for the pneumatic pressure; and a servo pneumatic controller coupled to the sensor and the proportional valve, the servo pneumatic controller for controlling the proportional valve in response to the measurement from the sensor. The valve stem control system can operate in connection with an injection molding machine.

Description

VALVE STEM CONTROL SYSTEM

TECHNICAL FIELD

The present disclosure relates to injection molding machines and in particular to valve stem control systems. BACKGROUND

Injection molding machines generally include a hopper for receiving resin, a barrel connected to the hopper and a screw that moves within the barrel to impart a force onto the resin to melt and move the resin along the barrel. The melted resin is injected from the barrel into a melt passage apparatus that defines one or more melt passage. The melted resin passes through the melt passage(s) to one or more nozzle. The melted resin is then expelled into a mold cavity through a gate defined in the nozzle. The mold cavity can be formed by clamping two mold plates together.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic view of a servo pneumatic controller system.

Figure 2 is a schematic depiction of components of a valve stem control system in isolation. Figure 3 is cross-sectional side view of a melt passage apparatus with a stem actuation plate.

Figure 4 is cross-sectional side view of a stem actuation plate in a melt passage apparatus.

Figure 5 is a schematic depiction of a valve stem control system with cross-sectional view of a melt passage apparatus with a stem actuation plate.

Figure 6A is a close-up cross-sectional side view of a valve stem in a retracted position (in which the gate is open).

Figure 6B is a close-up cross-sectional side view of a valve stem in an extended position (in which the gate is closed).

Figure 7 is a flowchart showing a method of controlling a plurality of valve stems in a melt passage apparatus. The drawings are not necessarily to scale and may be illustrated by phantom lines, diagrammatic representations and fragmentary views. In certain instances, details that are not necessary for an understanding of the embodiments or that render other details difficult to perceive may have been omitted. Like reference numerals are used in the drawings to identify like elements and features.

DETAILED DESCRIPTION

Disclosed generally is a valve stem control system. The valve stem control system can be used to control the flow of melt within or out of a melt passage apparatus of an injection molding machine. The valve stem control system can be a servo pneumatically operated valve stem assembly. The valve stem assembly can be used to open and close one or more gates of an injection molding machine. For example, the valve stem assembly can be used to open and close one or more gates at one or more outlets of a melt passage defined in a melt passage apparatus in an injection molding machine. By way of further example, the valve stem assembly can be used to open and close one or more gates of a melt passage apparatus in order to control the flow of a melted resin into one or more mold cavities.

The valve stem assembly includes valve stems that are connected to a stem actuation plate. The stem actuation plate is moved by pneumatic pressure or force, such as by a pneumatically operated piston. For example, the pneumatically operated piston can be connected to the stem actuation plate. The gas or air that causes the pneumatic pressure is metered out by a proportional valve. The air is metered out in order to control the amount or level of pressure operating to move the stem actuation plate. For example, the proportional valve can meter out the air to regulate the air pressure on two sides of the piston in order to create specific pressure differentials across the piston. The pressure differential can cause movement in the piston that in turn moves the stem actuation plate and thus the valve stems. The valve stems can move between a state or position in which the gate is open to allow melt to flow therethrough and a state or position in which the gate is closed (due to being blocked by the valve stem) to prevent melt from flowing therethrough.

A sensor, such as a position sensor, measures one or more characteristics of the valve stem assembly, such as a position of the stem actuation plate relative to a backing plate (or relative to another component or relative to its previous position, for example) or a position of a valve stem.

The servo pneumatic controller uses the sensed data to control the proportional valve. For example, the servo pneumatic controller can control the proportional valve which in turn controls the pressure operating on the stem actuation plate in order to move the stem actuation plate and hence the valve stems from a sensed position closer to a target position (or target value). In other words, the servo pneumatic controller can adjust the pressure differential across the piston in order to move the valve stem(s) closer to a target position. The target position can be from a target profile. The target profile can indicate relationships between the target position or target value and other parameters such as the temperature of the melt, the stage of the injection molding cycle, etc. By way of further example, the target position or target value can be one of a number of target characteristics that can be included in the target profile. Other characteristics can include speed of the valve stems, acceleration of the valve stems, temperature of the melt (or melted resin), the pressure acting on the melt, etc.

The operations of the servo pneumatic controller can occur automatically through a mold cycle without any intervention from a user. A mold cycle can be the series or set of operations implemented in an injection molding machine to melt resin, fill the mold cavity with resin and to cool the resin in the mold cavity, for example.

Servo pneumatically controlled valve stems can provide an increased level of stem motion control as compared to pneumatically controlled valve stems that do not use a servo pneumatic control system. In one aspect, the present disclosure describes a valve stem control system comprising: a stem actuation plate connected to a plurality of valve stems, movement of the stem actuation plate controlled by a pneumatic pressure; a sensor to measure a characteristic associated with the stem actuation plate; a proportional valve for controlling a supply of air for the pneumatic pressure; and a servo pneumatic controller coupled to the sensor and the proportional valve, the servo pneumatic controller for controlling the proportional valve in response to the measurement from the sensor.

In some embodiments the valve stem control system includes an air supply source for providing air to the proportional valve.

In some embodiments the valve stem control system includes a supplementary air supply source for providing supplementary air to the proportional valve. In some embodiments the valve stem control system includes a piston assembly connected to the stem actuation plate, the piston assembly comprising a piston movable within a piston housing, and the piston assembly defining at least in part: an extension chamber fluidly connected to the proportional valve, the extension chamber for holding air to apply a pneumatic pressure to move the piston within the piston housing in a direction toward the stem actuation plate; and a retraction chamber fluidly connected to the proportional valve, the retraction chamber for holding air to apply a pneumatic pressure to move the piston within the piston housing in a direction away from the stem actuation plate.

In some embodiments the proportional valve is configured to control the air flow to one or more of the retraction chamber and the extension chamber to create a pressure differential across the piston. In some embodiments the stem actuation plate is integral with the piston. In some embodiments, the valve stem control system includes a melt passage apparatus having a plurality of nozzle assemblies, the plurality of nozzle assemblies defining a part of a melt passage extending to respective gates defined in a mold for allowing melt to pass through and into one or more mold cavities, wherein: each of the plurality of valve stems is disposed within a portion of the melt passage defined in the respective nozzle assembly, and wherein the valve stems are configured to move between an extended position in which the valve stems block melt from passing through the gate and a retracted position in which the gate is open to allow melt to pass through.

In another aspect, the present disclosure describes a method of controlling a plurality of valve stems in a melt passage apparatus, the method comprising: measuring a characteristic associated with a pneumatically controlled stem actuation plate, the stem actuation plate connected to a plurality of valve stems; determining that the measured characteristic is different from a target value by at least a predetermined amount; and adjusting a pneumatic pressure applied to the stem actuation plate to adjust the characteristic to be closer to the target value.

In some embodiments, the method includes changing the target values. In some embodiments, changing the target value includes receiving an updated target value; and replacing the target value with the updated target value.

In some embodiments, the method includes evaluating one or more parameters associated with the melt passage apparatus and wherein changing the target value is performed in response to evaluating one or more parameters associated with the melt passage apparatus. In some embodiments, evaluating one or more parameters associated with the melt passage apparatus comprises measuring an amount of heat applied to one or more components of the melt passage apparatus.

In some embodiments, adjusting the pneumatic pressure applied to the stem actuation plate comprises metering a supply of air through a proportional valve. In some embodiments, measuring a characteristic comprises measuring a position of one or more of the plurality of valve stems.

In some embodiments, measuring a characteristic comprises measuring a position of the stem actuation plate.

In some embodiments, measuring a characteristic comprises measuring the pneumatic pressure. In some embodiments, measuring a characteristic comprises measuring a position of a piston, the piston connected to the stem actuation plate for moving the stem actuation plate.

In some embodiments, measuring a characteristic comprises measuring a pressure of melt within one or more of the melt passage apparatus and a mold cavity, the mold cavity for receiving melt expelled from the melt passage apparatus.

In another aspect, the present disclosure describes a control unit comprising: a memory for storing instructions; a processor for executing instructions stored on memory to: measure a characteristic associated with a pneumatically controlled stem actuation plate, the stem actuation plate connected to a plurality of valve stems; determine that the measured characteristic is different from a target value by at least a predetermined amount; and adjust a pneumatic pressure applied to the stem actuation plate to adjust the characteristic to be closer to the target value.

In some embodiments, the control unit includes a display unit having a screen for outputting in realtime a metric associated with the plurality of valve stems.

In another aspect, the present disclosure describes an injection molding machine comprising: a melt passage apparatus defining a melt passage for receiving melt from an extruder component, the melt passage apparatus comprising a plurality of nozzle assemblies defining respective gates, wherein the nozzle assemblies define portions of the melt passage fluidly connected to gates defined in one or more mold for distributing melt into one or more mold cavities; a stem actuation plate connected to a plurality of valve stems, movement of the stem actuation plate controlled by a pneumatic pressure, each of the plurality of valve stems is disposed within a portion of the melt passage defined in the respective nozzle assembly; a sensor to measure a characteristic associated with the stem actuation plate; a proportional valve for controlling a supply of air for the pneumatic pressure; and a servo pneumatic controller coupled to the sensor and the proportional valve, the servo pneumatic controller for controlling the proportional valve in response to the measurement from the sensor. In some embodiments the injection molding machine includes an air supply source for providing air to the proportional valve.

In some embodiments the injection molding machine includes a supplementary air supply source for providing supplementary air to the proportional valve.

In some embodiments the sensor is a position sensor. In some embodiments the characteristic associated with the stem actuation plate is a position of one or more of the plurality of valve stems. In some embodiments the characteristic associated with the stem actuation plate is a position of the stem actuation plate.

In some embodiments the melt passage apparatus includes the piston assembly.

In some embodiments the stem actuation plate is integral with the piston. Servo Pneumatic Control System

Figure 1 is a schematic diagram showing in the abstract components of an exemplary servo pneumatic controller system 100 suitable for use with a valve stem control system. Components of the servo pneumatic controller system 100 include a servo pneumatic controller 102, a sensor 104, an air supply source 106, a proportional valve 108, a moving element 110, and a load 112. The air supply source 106 can be a container or compartment of air or other gas suitable for providing pneumatic pressure. For example, the air supply source 106 can contain pressurized air or another pressurized gas suitable for providing pneumatic pressure. The air supply source 106 is fluidly connected to the proportional valve 108. For example, a fluid channel or tube can extend between the air supply source 106 and the proportional valve 108. Alternatively, the proportional valve 108 can be located on an opening of the air supply source 106. The air supply source 106 can be dedicated to the servo pneumatic controller system 100. Alternatively, the air supply source 106 can supply air (or air pressure) to other components of an associated machine (such as other pneumatically controlled or pneumatically operated components of an injection molding machine).

The proportional valve 108 is connected between the air supply source 106 and the moving element 110 or one or more pressure chambers associated with the moving element 110. The proportional valve 108 includes one or more valves that can open to allow air to flow between the air supply source 106 and the moving element 110 (or the pressure chamber(s)). The proportional valve 108 can partially open so as to meter out a specific amount of air (and hence the amount of air pressure). The proportional valve 108 can be configured so that the amount that the valves open can be proportional to the amount of air flow that passes through the respective valve opening.

The moving element 110 is any component that is movable and that can be moved with a pneumatic pressure. In other words, movement of the moving element 110 is controlled by a pneumatic pressure. For example the moving element 110 can be a piston that can be translated within a piston housing using pneumatic pressure. By way of further example, the proportional valve 108 can be connected along a fluid channel between the air supply source 106 and a pressure chamber of the moving element 110. In other words, the proportional valve 108 operates to meter out air flow between the air supply source 106 and the moving element 110 so as to provide specific levels of pneumatic pressure to actuate or move the moving element 110.

The moving element 110 is associated with a load 112 such that movement of the moving element 110 causes corresponding movement of the load 112. For example, the moving element 110 can engage with or be connected to the load 112. In an embodiment, the moving element 110 can be a piston and the load 112 is connected to the piston so that translation of the piston causes translation of the load 112. Therefore, as with the moving element 110, the load is also controlled with a pneumatic pressure.

The sensor 104 is configured to measure a characteristic associated with either the moving element 110 or the load 112 (or both). For example, the sensor 104 can be a position sensor that measures the position of the moving element 110 or load 112 relative to a baseline. The baseline can be predetermined, set automatically during operation of the servo pneumatic controller system 100, or it can be the relative position of another component. The sensor 104 can be associated with a memory (not shown) in order to store measured characteristics. Alternatively, the sensor 104 is configured to measure a characteristic associated with the air or gas used for the pneumatic pressure, such as the level or amount of pressure.

The sensor 104 transmits the measured characteristics (or sensed data) to the servo pneumatic controller 102.

The servo pneumatic controller 102 is connected to the proportional valve 108 so that the servo pneumatic controller 102 can control the operation of the proportional valve 108. For example, the servo pneumatic controller 102 can transmit electrical signals to control the opening and closing of the proportional valve 108. In this way the servo pneumatic controller 102 can control the amount of air pressure released by the air supply source 106 into the moving element's pressure chamber. By way of further example, the proportional valve 108 can comprise more than one valve that control the air supply more than one pressure chambers associated with the moving elementl 10. In such example embodiments, the servo pneumatic controller can control the air pressure released by the air supply source 106 into the more than one pressure chambers associated with the moving element 110. In this way the movement of the moving element 110 (which is controlled by the pressure in the pressure chambers) can be controlled. Other suitable configurations of known proportional valves 108 can be implemented in or used in accordance with the present disclosure.

The servo pneumatic controller 102 can be associated with a memory 114 and can include a processor 116 such as a microprocessor. Generally, the servo pneumatic controller 102 controls the proportional valve 108 in response to the measured characteristic(s) received from the sensor 104 in order to regulate or automatically control the movement or position of the load 112 to a desired level of movement or to a desired position.

In an exemplary embodiment of the servo pneumatic controller system 100, the servo pneumatic controller 102 maintains (in memory 114, for example) a target value or target position or target movement profile of the load 112 (or moving element 110). The target movement profile can include a series or set of target positions or target values that each relate to another parameter such as the timing of a mold cycle. The target values can identify values such as position, acceleration or other characteristics associated with the stem actuation plate 202 (or with another component of a melt passage apparatus). The received measured characteristic or sensed data is compared (for example by the operation of the processor 116 of the servo pneumatic controller 102) to the target value, which may be part of the target movement profile. For example, the measured characteristic or sensed data can be associated with the specific timing in the mold cycle by the operation of the processor 116 and this data and timing can be compared to the relevant target value in the target movement profile. If the measured characteristic indicates that the position of the load 112 (or moving element 110) differs from the target value by more than a predetermined amount, then the proportional valve 108 is adjusted so as to reduce this difference.

In an exemplary embodiment of a valve stem control system the components of a servo pneumatic controller system are implemented such that the moving element 110 is a piston (and the chamber is a piston housing), the load 112 is a stem actuation plate (or a plurality of valve stems) and the sensor 104 is a position sensor. The stem actuation plate together with the plurality of valve stems can be referred to as the valve stem assembly. The load 112 can be the valve stem assembly. Thus, movement of the piston causes movement of the valve stems. Each valve stem is configured to move between a retracted position and an extended position. Valve Stem Control System

A valve stem control system 200 generally includes a pneumatically controlled stem actuation plate, a plurality of valve stems connected to the stem actuation plate, a sensor 104 for measuring a characteristic associated with the pneumatically controlled stem actuation plate, a proportional valve 108 for controlling a supply of air for the pneumatic pressure, and a servo pneumatic controller 102 coupled to (or at least in communication with) both the sensor 104 and the proportional valve 108 in order to control the proportional valve 108 in response to the measurement or data from the sensor 104. Figure 2 is a schematic depiction of an exemplary embodiment of components of a valve stem control system 200 in isolation. The valve stem control system 200 shown in figure 2 includes a stem actuation plate 202, five valve stems 204 connected to the stem actuation plate 202, two piston assemblies 260 including two pistons 206 movably disposed within respective piston housings 208, a sensor 104, a servo pneumatic controller 102 and a proportional valve 108. The servo pneumatic controller 102 and proportional valve 108 are housed in a melt distribution controller 216. The melt distribution controller 216 is connected to an interface 218 and can be used to control certain operations of components of an injection molding machine or of a melt passage apparatus. In an alternative embodiment, the servo pneumatic controller 102 and proportional valve 108 are housed in a separate component or element (e.g. separate from the melt distribution controller 216).

The five valve stems 204 are connected to the stem actuation plate 202. There can be a different number of valve stems 204 connected to the stem actuation plate 202 in other embodiments. For example, there can be four valve stems 204 or two valve stems 204 connected to the stem actuation plate 202. By way of further example, the stem actuation plate 202 can be connected to a plurality of valve stems 204. In yet further examples, the stem actuation plate 202 can have ninety-six valve stems 204 attached to it. The movement of the stem actuation plate 202 causes a similar movement of each valve stem 204 connected to the stem actuation plate 202.

With reference to figure 1, the pistons 206 are an example of the moving element 110. The stem actuation plate 202 is an example of a load 112. Movement of the stem actuation plate 202 is thus controlled by a pneumatic pressure and the stem actuation plate 202 may be referred to as a pneumatically controlled stem actuation plate 202.

With reference again to figure 2, the pistons 206 are operatively engaged to the stem actuation plate 202 and are each movable within the respective piston housings 208. For example, the pistons 206 can be connected to the stem actuation plate 202. The movement of the pistons 206 cause corresponding movement of the stem actuation plate 202 which causes corresponding movement of the valve stems 204. The pistons 206 are controlled by a pneumatic pressure within the piston housings 208. In particular, the pressure differential acting on a top side 220 of the piston relative to a bottom side 222 of the piston 206 causes the piston 206 to move within the piston housing 208. In other words, an extension and a retraction of the piston 206 are caused by the pneumatic pressure in the piston housing 208. There can be different numbers of pistons 206 (and respective piston housings 208) connected to the stem actuation plate 202 in other embodiments. For example, there may be only one piston 206 movable within a piston housing 208 and attached to the stem actuation plate 202. By way of further example, there may be two stem actuation plates 202 with each stem actuation plate 202 being connected to a dedicated piston 206 or more than one dedicated pistons 206 operating within respective piston housings 208. Actuators other than pistons 206 can be used within the scope of this disclosure.

The proportional valve 108 controls the supply of air for the pneumatic pressure. For example, the proportional valve 108 controls the supply of air (or air flow) to and from the top side 220 of the piston 206 and the bottom side 222 of the piston 206 in order to control the pressure differential therebetween. Arrows 280 show the direction of air flow from the proportional valve 108 to the top side 202 of the piston 206 and the bottom side 222 of the piston 206.

In an alternative embodiment, the proportional valve 108 controls the air flow and consequent pressure to only one side (one of the top side 220 or the bottom side 222, for example) of the piston 206. Air flow passages (not shown) are disposed between the proportional valve 108 and the piston housing 208 in order to provide for air flow and resulting pneumatic pressure. For example, there can be two different air flow passages connected to the piston housing 208 to provide (or remove) air pressure to the top side 220 of the piston 206 and the bottom side 222 of the piston 206 respectively. In an embodiment, the valve stem control system 200 includes the air supply source 106 for providing air to the proportional valve 108. The proportional valve 108 is connected to the air supply source 106 in order to meter out the air through the opening or closing of the valve(s).

In a further embodiment, a supplementary air supply source (not depicted) is included in the valve stem control system 200 for providing supplementary air to the proportional valve 108. For example, the supplementary air supply source can be used when the air supply source 106 does not provide adequate air pressure.

With reference to figure 1 and figure 2, the servo pneumatic controller 102 includes a processor 116 and memory 114. The processor 116 executes instructions stored on the memory 114. The processor 116 and memory 114 can be firmware (or located in firmware) and can be embedded into the melt distribution controller 216. For example, the processor 116 and memory 114 can be housed in or integrated with the melt distribution controller 216. For example, the servo pneumatic controller 102 can store data or instructions on the memory of the melt distribution controller 216. By way of further example, the servo pneumatic controller 102 can be a separate program or application stored on the memory of the melt distribution controller 216 that is executed by the processor of the melt distribution controller 216 or on another controller associated with the injection molding machine. The memory 114 or processor 116 can be pre-programmed or can operate upon instructions received through the interface 218 (or through another communication portal or another interface). The interface 218 can be a user interface such as shown in figure 2, or it can be an interface to another computer such as a wireless connection to a remote handheld device.

The servo pneumatic controller 102 is coupled to the sensor 104 and the proportional valve 108. The servo pneumatic controller 102 controls the operation of the proportional valve 108 in order to control the air pressure (or pressure differential) acting on the piston 206. For example, the servo pneumatic controller 102 can be connected to the proportional valve 108 in order to control the amount that the valve(s) is opened or closed and consequently the amount of air flow passing through the valve.

The sensor 104 can be disposed in or connected to a component within the vicinity of the stem actuation plate 202. The sensor 104 measures a characteristic associated with the stem actuation plate 202. For example, the sensor can measure characteristics such as the position, movement or acceleration of the stem actuation plate 202; the position, movement or acceleration of the valve stems 204; or the position, movement or acceleration of the piston 206 that actuates the stem actuation plate 202. The sensor can be an inductance sensor, a capacitance sensor or a linear motion sensor (LVDT). Other sensors suitable for use with a pneumatically operated moving element 110 can be used.

In other embodiments, there is more than one sensor 104. The sensors 104 can be located at different positions in order to measure different characteristics associated with the stem actuation plate 202 (or with other components of the valve stem assembly). The sensor 104 is in communication with the servo pneumatic controller 102 and transmits the sensed data or measured characteristic to the servo pneumatic controller 102. Figure 2 shows the transmission path 270 of data from the sensor 104 to the servo pneumatic controller 102. Alternatively, the servo pneumatic controller 102 can periodically poll the sensor 104 to retrieve the sensed data or measured characteristic. The communication of the data between the servo pneumatic controller 102 and the sensor 104 can be through a wire, such as a dedicated copper wire, or can be wireless. The servo pneumatic controller 102 controls the proportional valve 108 (or the operation of the proportional valve 108) in response to the measurement received from the sensor 104.

A target characteristic of the valve stem assembly or of the valve stems 204 or stem actuation plate 202 can be stored on the memory 114 of the servo pneumatic controller 102. The processor 116 compares the sensed data received from the sensor 104 to the relevant target characteristic of the valve stem assembly, or of the valve stems 204 or stem actuation plate 202 as the case may be, and adjusts the proportional valve 108 so that the sensed characteristic or sensed data of the valve stem assembly will become closer to the target characteristic. The interface 218 shown in the embodiment of figure 2 has a display screen. In one or more embodiments, the interface 218 has an input module or an output module or both. The input module can be a keyboard, a mouse, audio-controlled or a touch screen. The output module can be a display screen, such as in figure 2, or an audio-based or tactile-based output component. The display screen can be configured (or programmed in a memory associated with the melt distribution controller 216 for execution by a processor associated with the melt distribution controller 216) to display data representing a movement of one or more of the valve stems 204 or the stem actuation plate 202 or to display a representation of the pressure operating on the piston 206. Such display can be in real time. The data displayed can correspond to the data or characteristic measured by the sensor 104. The input module can receive input that can be stored in the memory of the melt distribution controller 216 or the memory 114 associated with the servo pneumatic controller 102. For example, the input can alter the instructions for the servo pneumatic controller 102 such as by changing a target value or target characteristic. The target characteristic can be set by input into the interface 218, for example. Melt Passage Apparatus

Figure 3 is a cross-sectional side view of an embodiment of a melt passage apparatus 300 along with a stem actuation plate 202 connected to valve stems 204. Figure 3 shows the valve stems 204 in an extended position. The valve stems 204 can be disposed within the melt passage apparatus 300. For example, the valve stems 204 (or valve stem assembly, which can include the stem actuation plate 202), can be used to control flow of melt within or out of the melt passage apparatus 300. The melt passage apparatus 300 includes a backing plate 302, a stem actuation plate 202, a center plate 304, a manifold plate 306 and a manifold 308. In accordance with the embodiment shown in figure 3, the backing plate 302 is connected to the center plate 304 using bolts 310, and the center plate 304 is connected to the manifold plate 306 using bolts 310. Connectors other than bolts 310 can be used. A guide pin 312 is disposed within the backing plate 302, stem actuation plate 202 and center plate 304 for alignment of the plates 302, 202, 304. The melt passage apparatus 300 can also have a plurality of nozzle assemblies 332.

The piston assembly 260 is located inside of a compartment in the backing plate 302. For example, the piston assembly 260 can be connected to the backing plate 302 or can be partially integral with the backing plate 302. The piston assembly 260 includes a cover plate 316, a piston housing 208 and a piston 206. The piston 206 is movable within the piston housing 208. The piston housing 208 can also be defined by the backing plate 302 or by one or more components of the piston assembly 260, for example. The piston assembly 260 defines at least in part an extension chamber 320 and a retraction chamber 322. In an embodiment, the piston housing 208 defines the extension chamber 320. In another embodiment, the piston housing 208 together with one or more components of the piston assembly 260 defines the extension chamber 320. The extension chamber 320 is proximate to a back face of (or the top side 220 of) the piston 206, which faces away from the stem actuation plate 202. The retraction chamber 322 is on a front side (or bottom side 222) of the piston 206, which faces toward the stem actuation plate 202. In an embodiment, the piston housing 208 defines the retraction chamber 322. In another embodiment, the piston housing 208 together with one or more components of the piston assembly 260 defines the retraction chamber 322. Each of the extension chamber 320 and retraction chamber 322 are fluidly connected to the proportional valve 108 (not shown in the figures). In other embodiments the backing plate 302 or another component of the melt passage assembly 300 defines, in part, one or both of the extension chamber and the retraction chamber 322.

In an embodiment, the extension chamber 320 is fluidly connected to the proportional valve 108 and the retraction chamber 322 is fluidly connected to the proportional valve 108. The extension chamber 320 can hold air to apply a pneumatic pressure to move the piston 206 within the piston housing 208 in a direction toward the stem actuation plate 202 or toward the manifold 308. Similarly, the retraction chamber 322 can hold air to apply a pneumatic pressure to move the piston 206 within the piston housing 208 in a direction away from the stem actuation plate 202 or away from the manifold 308.

Structures or components other than a piston assembly 260 suitable for pneumatically operating the stem actuation plate 202 otherwise in accordance with this disclosure can be implemented.

In the depicted embodiment, the cover plate 316 is connected to the backing plate 302 by bolts 310 and the piston 206 is connected to the stem actuation plate 202 by a bolt 310. Connectors other than bolts 310 can be used to connect the cover plate 316 to the backing plate 302 and the stem actuation plate 202 to the piston 206. The piston 206 can reciprocate within the piston housing 208 in response to the pneumatic pressure differential across the piston 206. In an embodiment, the proportional valve 108 is configured to control the air flow to one or more of the retraction chamber 322 and the extension chamber 320 to create a pressure differential across the piston 206. For example, when the proportional valve 108 operates to increase the air pressure (or pneumatic pressure) in the extension chamber 320 relative to the air pressure in the retraction chamber 322, the pressure differential across the piston 206 forces the piston 206 towards the center plate 304 (or towards the manifold 308). By way of further example, when the proportional valve 108 operates to increase the air pressure in the retraction chamber 322 relative to the air pressure in the extension chamber 320, the pressure differential across the piston 206 forces the piston 206 away from the center plate 304 (and away from the manifold 308). In figure 3, the valve stems 204 are in the extended position and the retraction chamber 322 is consequently reduced in size relative to the extension chamber 320 as compared to the relative sizes when the valve stems 204 are in the retracted position.

With reference to both figures 3 and 4, the manifold 308 is located within an impression in the manifold plate 306. The manifold 308 includes three apertures into which three respective manifold bushings 326 are held. The manifold bushings 326 each define a portion of the melt passage 324 and are each connected to a respective backup pad 330 at its end proximate to the center plate 304. A different number of manifold bushings 326 can be included in different embodiments.

The end of the manifold bushings 326 that are distal to the center plate 304 are each engaged to respective nozzle assemblies 332. The engagement between each nozzle assembly 332 and the respective manifold bushing 326 can be a slidable engagement as shown in figure 4 in which the nozzle assembly 332 and the manifold bushing 326 are held together with pressure.

According to the embodiments depicted in figures 3 and 4, each valve stem 204 is connected to the backing plate 302 using a respective set screw 333. Appropriate connectors other than set screws 333 can be used to connect the valve stem 204 to the backing plate 302. Each valve stem 204 extends through a passage in the center plate 304, through the passage in the manifold bushing 326, and through the passage in the nozzle assembly 332. Each valve stem 204 can be moved along its longitudinal axis within a portion of such passages. The passages within which the valve stem 204 reciprocates can include a portion of a melt passage 324.

The melt passage 324 is a channel or passage through which the melted resin flows. For example, the melt passage 324 can be defined as extending through an extruder component 360, the manifold 308, the manifold bushing 326 and the nozzle assembly 332. The resin can pass from the extruder component 360 through the melt passage 324 to the end of the nozzle assembly 332 distal to the manifold 308. By way of further example, the melt passage 324 can receive melted resin from the extruder component 360. The extruder component 360 can be a component that is not part of the melt passage apparatus 300.

Each of the plurality of valve stems 204 is disposed within a portion of the melt passage 324 defined in the respective nozzle assembly 332.

The sensor 104 is attached to the backing plate 302. The sensor 104 shown in the embodiment depicted in figure 3 is a position sensor that measures the position of the stem actuation plate 202. The sensor 104 can transmit the measured position data (for example, the position of the stem actuation plate 202 as measured by the sensor 104) back to the servo pneumatic controller 102. As noted above, the sensor 104 can measure other characteristics such as the position of one or more of the valve stems 204, the pressure of the melt within the melt passage 324 or within the mold cavity, the pneumatic pressure acting on the stem actuation plate 202, etc.

With reference to Figure 4, which shows the nozzle assemblies 332 in detail, each nozzle assembly 332 can include a nozzle housing 404, a nozzle tip 406, a tip insulator 408, a locating insulator 410 and a spring 412, among other components not specifically described. The nozzle assembly 332 defines a portion of the melt passage 324, which can be fluidly connected to the portion of the melt passage 324 defined by the manifold bushing 326.

A heater 414 can be disposed along a portion of the nozzle assembly 332 in order to provide heat to a portion of the melt passage 324. A gate 416 is defined at the end of the melt passage 324 proximate to the nozzle tip 406. For example, the gate 416 may be defined in the nozzle assembly 332. By way of further example, the plurality of nozzle assemblies 332 can each define a respective gate 416 for allowing melt to pass through and into one or more mold cavities.

The melt passage apparatus 300 can be configured to receive melted resin (e.g. from an extruder) and to maintain the resin in a melted phase (e.g. using one or more heater). The melted resin can be received into the melt passage 324 defined in the melt passage apparatus 300 and can move along the melt passage 324 and exit through the gates 416. When the melted resin exits the melt passage 324 through the gates 416 it can enter into one or mold cavities (not shown).

Figure 5 shows the melt passage apparatus 300 of figure 3 (shown in cross-section) together with an embodiment of the valve stem control system 200 (shown in schematic). The sensor 104 in the embodiment in figure 5 is a position sensor that can measure the position of the stem actuation plate 202. In the embodiment shown in figure 5, there are three valve stems 204 connected to the stem actuation plate 202; although other embodiments may have fewer or more valve stems 204 connected to the stem actuation plate 202. The melt passage 324 leading to the manifold bushing 326 is not shown. Similarly, the fluid passageways for allowing air (or other gas for use in providing pneumatic pressure) to flow between the proportional valve 108 and the piston assembly 260 in order to actuation the piston 206 (by providing pressure differential) are not shown.

Accordingly, the valve stem control system 200 can be used to control the flow of melt within a melt passage apparatus 300. Moreover, the valve stem control system 200 can be implemented at least partially within the melt passage apparatus 300. Valve Stem Movement

The embodiment of figure 6A shows a cross-sectional side view of a portion of the valve stem 204 in the retracted position along with a portion of the nozzle assembly 332. The embodiment of figure 6B shows a close-up cross-sectional side view of a portion of the valve stem 204 in the closed position along with a portion of the nozzle assembly 332. With reference to both figures 6A and 6B, the nozzle housing 404 defines in part the melt passage 324 within which the valve stem 204 is disposed. The valve stem 204 can be movable within a portion of the melt passage 324 in that it can translate along its longitudinal axis as a result of the movement of the stem actuation plate 202 (not shown in figures 6A and 6B). For example, the valve stems 204 can be configured to move between an extended position, in which the valve stems 204 block melt from passing through the respective gate 416, and a retracted position, in which the respective gate 416 is open to allow melt to pass through.

In the exemplary embodiment depicted in figures 6 A and 6B, the nozzle tip 406 abuts the nozzle housing 404 and defines in part the melt passage 324 so that the melt passage 324 passes through the nozzle housing 404 and nozzle tip 406. Similarly, the valve stem 204 is disposed within the portion of the melt passage 324 that is defined in the nozzle tip 406. A nozzle tip insulator 408 is disposed near an end of the nozzle tip 406 distal to the nozzle housing 404. The tip insulator 408 can be fabricated from an insulating material. The melt passage 324 extends through the nozzle tip 406 through an outlet of the nozzle tip 406 to the gate 416. The gate 416 is the opening defined in a mold which leads to a mold cavity where the melt can be expelled into. The mold cavity is not shown in the figures.

In figure 6A the valve stem 204 is retracted so that the melt passage 324 is (in part) a fluid passageway from the nozzle housing 404 through the nozzle tip 406 and through the gate 416. In figure 6B the valve stem 204 is extended so that it blocks the fluid passage to the gate 416. Accordingly, when the valve stem 204 is extended the melt is blocked from passing through the gate 416.

When the valve stem 204 is in the retracted position, the gate 416 is open. When the gate 416 is open the melt passage 324 is fluidly connected to the gate 416 to allow melt to pass through the gate 416. When the valve stem 204 is in the extended position, the gate 416 is closed. When the gate 416 is closed the valve stem 204 is inside of the gate 416 so as to block the flow of melt from the melt passage 324 through the gate 416. Accordingly, the valve stem 204 can be referred to as being in the "open position" when it is in the retracted position and as being in the "closed position" when it is in the extended position. Method of Operation In operation the valve stem control system 200 can control the opening and closing of the gate 416. Similarly, the valve stem control system 200 can control the flow of melt in the melt passage assembly 300.

A flow chart showing an embodiment of a method 700 of controlling a plurality of valve stems 204 in a melt passage apparatus 300 is depicted in figure 7. The method 700 can be carried out using the valve stem control system 200. For instance, certain elements or operations of the method 700 can be stored as instructions on the memory 114 associated with the servo pneumatic controller 102 and such instructions can be executed by the processor 116 associated with the servo pneumatic controller 102. At 702 a characteristic associated with a pneumatically controlled stem actuation plate 202 is measured. The stem actuation plate 202 is connected to a plurality of valve stems 204. The measurement of the characteristic of the stem actuation plate 202 can be performed by the sensor 104. In one or more embodiments, the characteristic being measured is related to the position of one or more of the valve stems 204 within the melt passage 324. For example, the characteristic being measured can be the relative position of the valve stem 204 (relative to a predetermined baseline position or relative to another component of the melt passage apparatus 300), the acceleration of the valve stem 204 (as measured by a sensor 104 such as an accelerometer). By way of further examples, the characteristic being measured can be the pressure of resin within the melt passage 324 or within the mold cavity, or another suitable characteristic. In an embodiment, the sensor 104 is a position sensor that measures a position of one or more of the plurality of valve stems 204. Alternatively, the position sensor measures a position of the stem actuation plate 202.

In an embodiment, the sensor 104 can be a pressure sensor used to measure the pressure associated with the melt in one or more areas of the melt passage apparatus 300. For example, the sensor 104 can measure the pressure of the melt in the melt passage 324. Alternatively, the pressure sensor can be used to measure the pneumatic pressure associated with a chamber of the piston assembly 260.

At 704, it is determined that the measured characteristic is different from a target value by at least a predetermined amount. The target value can be a value stored in a memory, such as the memory 114 associated with the servo pneumatic controller 102. For example, the target value can be stored in the memory 114 as a result of input received through the interface 218. Alternatively, the target value can be automatically determined based on characteristics related to the melt passage apparatus 300 or to the resin that will be passing through the melt passage apparatus 300. Such characteristics can be predetermined or can be measured during operation of the injection molding machine, for example. At 706, the pneumatic pressure applied to the stem actuation plate 202 is adjusted to adjust the characteristic to be closer to the target value. This adjustment to the pneumatic pressure can be performed automatically in response to determining 704 that the measured characteristic is different from the target value by a predetermined amount. For example, if the sensor 104 is a position sensor it can measure the position of the stem actuation plate 202 and transmit that measurement to the servo pneumatic controller 102. The servo pneumatic controller 102 can then compare the position measurement with a target value that is stored in memory 114. The target value can be associated with a position profile of the stem actuation plate 202. The position profile can have a plurality of target values that identify desired positions with each target value associated with a different time frame or a different operational aspect of the stem actuation plate 202 (or of the injection molding machine). If it is determined that the measured position is different from the target value by more than a predetermined amount, then the servo pneumatic controller 102 can adjust the proportional valve 108 in order to move the stem actuation plate 202 to a position closer to the position identified in the target value. In accordance with an embodiment, if it is determined that the measured characteristic is not different from the target value or if it is different from the target value by less than the predetermined amount, then the pneumatic pressure is not adjusted.

Adjusting the pneumatic pressure applied to the stem actuation plate 202 can include metering a supply of gas or air through the proportional valve 108. For example, the servo pneumatic controller 102 can send an instruction, such as through an electrical communication, to the proportional valve 108 to adjust the air pressure applied to the stem actuation plate 202. The adjustment to the air pressure can be in proportion to the amount of air pressure required to change the measured characteristic to be closer to the target value.

In one or more embodiment, the target value can be (optionally) changed, altered or adjusted. Optionally (at arrow 709), an updated target value is received 710. For example, the updated target value can be received through the interface 218 or it can be otherwise received electronically such as through a wireless communication. The updated target value can be received at the servo pneumatic controller 102.

Then, after receiving 710 the updated target value, the target value is replaced, at 712, with the updated target value 712. When it is determined that the measured characteristic is different from the target value by a predetermined amount (at 704), the target value used in the determination is the updated target value 712. In yet another optional embodiment, the updated target value can be generated by the servo pneumatic controller 102 based on one or more parameter or characteristic associated with the melt passage apparatus 300. For example, following arrow 707, optionally at 708 one or more parameters associated with the melt passage apparatus 300 are evaluated. In response to evaluating the one or more parameters the target value can be changed (such as at 710, 712). The evaluation of one or more parameters associated with the melt passage apparatus 300 can include measuring an amount of heat applied to one or more components of the melt passage apparatus 300. Other parameters can include an identification or determination of the stage of the injection molding process, the number of cycles completed in the injection molding process, the type of resin passing through the melt passage apparatus, the temperature of the resin, etc.

The target value can be one of a set of target values stored in the target profile. The target profile can associate each target value with specific value ranges for specific parameters associated with the melt passage apparatus 300. Thus, in an embodiment, the target value can be determined by a look up of the target profile based on a value of one or more parameters associated with the melt passage apparatus 300.

The method 700 can be implemented using a control unit (e.g. the melt distribution controller 216 or the servo pneumatic controller 102). The control unit can include a memory and a processor that executes instructions stored on the memory to carry out the method 700. The memory and processor can be the memory 114 and processor 116 associated with the servo pneumatic controller 102. The control unit can be associated with a display unit (e.g. the interface 218) that has a screen for outputting in real-time a metric associated with the plurality of valve stems 204. For example, the screen can output the position or acceleration of one or more of the valve stems 204, or the pressure in the melt passage 324 or the pressure in the mold cavity.

Other non- limiting embodiments, modifications and equivalents will be evident to one of ordinary skill in the art in view of the present disclosure.

This disclosure has presented one or more non-limiting exemplary embodiments. It will be clear to those skilled in the art that modifications and variations can be made to the disclosed non-limiting embodiments without departing from the intended scope of this disclosure. As such, the described non-limiting embodiments ought to be considered to be merely illustrative of some of the features or elements of this disclosure as a whole. Other beneficial results can be realized by applying the non- limiting embodiments in a different manner or modifying them in ways known to those familiar with the art. Certain features or sub-features of one embodiment may be combined with certain features or sub-features of another embodiment to arrive at a combination of features not specifically described above but still within the intended scope of the disclosure. Any such suitable and workable combination of features would be known to persons skilled in the relevant art after reviewing the present disclosure.

Claims

WHAT IS CLAIMED IS:

1. A valve stem control system, comprising: a stem actuation plate connected to a plurality of valve stems, movement of the stem actuation plate controlled by a pneumatic pressure; a sensor to measure a characteristic associated with the stem actuation plate; a proportional valve for controlling a supply of air for the pneumatic pressure; and a servo pneumatic controller coupled to the sensor and the proportional valve, the servo pneumatic controller for controlling the proportional valve in response to the measurement from the sensor.

2. The valve stem control system of claim 1, further comprising: an air supply source for providing air to the proportional valve.

3. The valve control system of claim 2, further comprising: a supplementary air supply source for providing supplementary air to the proportional valve.

4. The valve stem control system of any one of claims 1 to 3, wherein the sensor is a position sensor.

5. The valve stem control system of claim 4, wherein the characteristic associated with the stem actuation plate is a position of one or more of the plurality of valve stems.

6. The valve stem control system of claim 5, wherein the characteristic associated with the stem actuation plate is a position of the stem actuation plate.

7. The valve stem control system of any one of claims 1 to 6, further comprising a piston assembly connected to the stem actuation plate, the piston assembly comprising a piston movable within a piston housing, and the piston assembly defining at least in part: an extension chamber fluidly connected to the proportional valve, the extension chamber for holding air to apply a pneumatic pressure to move the piston within the piston housing in a direction toward the stem actuation plate; and a retraction chamber fluidly connected to the proportional valve, the retraction chamber for holding air to apply a pneumatic pressure to move the piston within the piston housing in a direction away from the stem actuation plate.

8. The valve stem control system of claim 7, wherein the proportional valve is configured to control the air flow to one or more of the retraction chamber and the extension chamber to create a pressure differential across the piston.

9. The valve stem control system of claim 7 or 8, wherein the stem actuation plate is integral with the piston.

10. The valve stem control system of any one of claims 1 to 9, further comprising: a melt passage apparatus having a plurality of nozzle assemblies, the plurality of nozzle assemblies defining a part of a melt passage extending to respective gates defined in a mold for allowing melt to pass through and into one or more mold cavities, wherein: each of the plurality of valve stems is disposed within a portion of the melt passage defined in the respective nozzle assembly, and wherein the valve stems are configured to move between an extended position in which the valve stems block melt from passing through the gate and a retracted position in which the gate is open to allow melt to pass through.

11. A method of controlling a plurality of valve stems in a melt passage apparatus, the method comprising: measuring a characteristic associated with a pneumatically controlled stem actuation plate, the stem actuation plate connected to a plurality of valve stems; determining that the measured characteristic is different from a target value by at least a predetermined amount; and adjusting a pneumatic pressure applied to the stem actuation plate to adjust the characteristic to be closer to the target value.

12. The method of claim 11, further comprising changing the target value.

13. The method of claim 12, wherein changing the target value comprises: receiving an updated target value; and replacing the target value with the updated target value.

14. The method of claim 12 or 13, further comprising evaluating one or more parameters associated with the melt passage apparatus and wherein changing the target value is performed in response to evaluating one or more parameters associated with the melt passage apparatus.

15. The method of claim 14, wherein evaluating one or more parameters associated with the melt passage apparatus comprises measuring an amount of heat applied to one or more components of the melt passage apparatus.

16. The method of any one of claims 11 to 15, wherein adjusting the pneumatic pressure applied to the stem actuation plate comprises metering a supply of air through a proportional valve.

17. The method of any one of claims 11 to 16, wherein measuring a characteristic comprises measuring a position of one or more of the plurality of valve stems.

18. The method of any one of claims 11 to 17, wherein measuring a characteristic comprises measuring a position of the stem actuation plate.

19. The method of any one of claims 11 to 18, wherein measuring a characteristic comprises measuring the pneumatic pressure.

20. The method of any one of claims 11 to 19, wherein measuring a characteristic comprises measuring a position of a piston, the piston connected to the stem actuation plate for moving the stem actuation plate.

21. The method of any one of claims 11 to 20, wherein measuring a characteristic comprises measuring a pressure of melt within one or more of the melt passage apparatus and a mold cavity, the mold cavity for receiving melt expelled from the melt passage apparatus.

22. A control unit comprising: a memory for storing instructions; a processor for executing instructions stored on memory to: measure a characteristic associated with a pneumatically controlled stem actuation plate, the stem actuation plate connected to a plurality of valve stems; determine that the measured characteristic is different from a target value by at least a predetermined amount; and adjust a pneumatic pressure applied to the stem actuation plate to adjust the characteristic to be closer to the target value.

23. The control unit of claim 22, further comprising: a display unit having a screen for outputting in real-time a metric associated with the plurality of valve stems.

24. An injection molding machine comprising: a melt passage apparatus defining a melt passage for receiving melt from an extruder component, the melt passage apparatus comprising a plurality of nozzle assemblies, wherein the nozzle assemblies define portions of the melt passage fluidly connected to gates defined in one or more molds for distributing melt into one or more mold cavities; a stem actuation plate connected to a plurality of valve stems, movement of the stem actuation plate controlled by a pneumatic pressure, each of the plurality of valve stems is disposed within the portion of the melt passage defined in the respective nozzle assembly; a sensor to measure a characteristic associated with the stem actuation plate; a proportional valve for controlling a supply of air for the pneumatic pressure; and a servo pneumatic controller coupled to the sensor and the proportional valve, the servo pneumatic controller for controlling the proportional valve in response to the measurement from the sensor.

25. The injection molding machine of claim 24, further comprising: an air supply source for providing air to the proportional valve.

26. The injection molding machine of claim 25, further comprising: a supplementary air supply source for providing supplementary air to the proportional valve.

27. The injection molding machine of any one of claims 24 to 26, wherein the sensor is a position sensor.

28. The injection molding machine of claim 27, wherein the characteristic associated with the stem actuation plate is a position of one or more of the plurality of valve stems.

29. The injection molding machine of claim 28, wherein the characteristic associated with the stem actuation plate is a position of the stem actuation plate.

30. The injection molding machine of any one of claims 24 to 28, wherein the melt passage apparatus comprises a piston assembly connected to the stem actuation plate, the piston assembly comprising a piston movable within a piston housing, and the piston assembly defining at least in part: an extension chamber fluidly connected to the proportional valve, the extension chamber for holding air to apply a pneumatic pressure to move the piston within the piston housing in a direction toward the stem actuation plate; a retraction chamber fluidly connected to the proportional valve, the retraction chamber for holding air to apply a pneumatic pressure to move the piston within the piston housing in a direction away from the stem actuation plate.

31. The injection molding machine of claim 30, wherein the proportional valve is configured to control the air flow to one or more of the retraction chamber and the extension chamber to create a pressure differential across the piston.

32. The injection molding machine of any one of claims 30 to 31, wherein the stem actuation plate is integral with the piston.