Gas control system, manufacturing apparatus, and method

Abstract

To provide an alternative print assembly and a component thereof for controlling a pressure directed to a printhead so that clogging in a nozzle of the printhead can be decreased.SOLUTION: A gas control system 106 includes: a positive pressure vessel 202; a negative pressure vessel 204; a first pressure control valve 206 configured to control a flow of gas to and from a first manifold of a printhead assembly; and a second pressure control valve 208 configured to control a flow of gas to and from a second manifold of the printhead assembly. During a normal positive pressure mode, gas flows from the positive pressure vessel to the first manifold and the second manifold through one of the first pressure control valve and the second pressure control valve. During a positive pressure purge mode, gas from the positive pressure vessel flows to the first manifold and the second manifold by bypassing through the first pressure control valve and the second pressure control valve.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] TECHNICAL FIELD This disclosure relates to print assemblies, and more particularly to a control system for a printhead in a manufacturing apparatus and a method for using the same. [Background technology]

[0002] Print assembly can be used to "build" an object, such as a three-dimensional object or part, layer by layer from a build material. Early iterations of print assembly were used for prototyping three-dimensional parts. However, as print assembly technology improves, there is growing interest in using print assembly for large-scale commercial manufacturing of parts. Summary of the Invention [Means for solving the problem]

[0003] One aspect of the disclosure is a gas control system including a positive pressure container, a first pressure control valve configured to control a first flow of gas between a negative pressure container and a first manifold of a printhead assembly, and a second pressure control valve configured to control a second flow of gas between a second manifold of the printhead assembly, wherein during a positive pressure normal mode, a primary flow of gas forming the first flow of gas and the second flow of gas flows from the positive pressure container to the first and second manifolds through a respective one of the first and second pressure control valves, and during a positive pressure purge mode, the first flow of gas and the second flow of gas from the positive pressure container bypass the first and second pressure control valves to flow to the first and second manifolds. [Brief description of the drawings]

[0004] [Figure 1]FIG. 1 illustrates a schematic of a manufacturing apparatus including a gas control system and a printhead assembly according to one or more embodiments shown and described herein. [Diagram 2] FIG. 2 illustrates a schematic of a manufacturing system for operating the manufacturing apparatus of FIG. 1 according to one or more embodiments shown and described herein. [Diagram 3] FIG. 3 generally illustrates a perspective view of the gas regulation system of FIG. 1 according to one or more embodiments shown and described herein. [Figure 4] FIG. 4 illustrates generally components of the gas control system of FIG. 3 and the printhead of the printhead apparatus of FIG. 1 in accordance with one or more embodiments shown and described herein. [Diagram 5] FIG. 5 illustrates generally gas flow through the gas regulation system of FIG. 3 during a positive pressure purge mode, according to one or more embodiments shown and described herein. [Figure 6] FIG. 6 illustrates generally gas flow through the gas regulation system of FIG. 3 during a negative pressure purge mode, according to one or more embodiments shown and described herein. [Figure 7] FIG. 7 illustrates generally gas flow through the gas regulation system of FIG. 3 during normal positive pressure mode, according to one or more embodiments shown and described herein. [Figure 8] FIG. 8 illustrates generally gas flow through the gas regulation system of FIG. 3 during normal negative pressure mode, according to one or more embodiments shown and described herein. [Figure 9] FIG. 9 illustrates a schematic depiction of gas flow through the gas control system of FIG. 3 during an embodiment of a calibration mode, according to one or more embodiments shown and described herein. [Figure 10] FIG. 10 is a schematic depiction of gas flow through the gas control system of FIG. 3 during another embodiment of the calibration mode, according to one or more embodiments shown and described herein. [Figure 11] FIG. 11 illustrates a schematic depiction of gas flow through the gas regulation system of FIG. 3 during a cleaning mode, according to one or more embodiments shown and described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] The embodiments illustrated in the drawings are exemplary in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of the exemplary embodiments can be understood when read in conjunction with the drawings, in which like structure is indicated with like reference numerals.

[0006] Print assemblies utilized in a variety of contexts, including, for example, manufacturing applications, jet printing applications, and other print types, generally include problems parallel to those discussed above. For example, manufacturing equipment generally includes print assemblies, also referred to as printhead devices, which deposit material through an array of ejection nozzles during the manufacturing process. These printhead devices typically utilize manifolds having dual reservoirs to control inlet and outlet flows to the individual printheads. However, these nozzles can become clogged with binder, thus requiring a purge operation to alleviate the clogging. To purge the printhead nozzles, electric pump-based pressure control systems can be utilized. However, such electric pump-based systems are not well suited to operate with binders in an inert gas atmosphere. Specifically, electric pump-based systems cannot be easily and safely used with flammable materials, and electric pump-based systems are generally slow to increase and decrease both pressure and flow rate. Additionally, electric pump-based systems are more susceptible to failure of electromechanical components.

[0007] Therefore, there is a need for an alternative print assembly and its components for controlling the pressure directed to the printhead so that clogging in the nozzles of the printhead can be addressed.

[0008] Reference will now be made in detail to embodiments of a manufacturing apparatus and its components, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or similar parts. An embodiment of a manufacturing apparatus, as illustrated generally in FIG. 1, includes a printhead assembly including a first manifold, a second manifold, and one or more printheads, a binder control system, a gas control system, a power supply, and a binder reservoir. The power supply provides power to the binder control system, the gas control system, and the printhead assembly. The binder control device controls the flow of binder from the binder reservoir to each of the first and second manifolds. The gas control device controls the gas flow from an external gas supply to each of the first and second manifolds, and regulates the gas flow during binder flow operations. During a purge operation, gas can be rapidly circulated between the gas control system and the manifolds to purge clogged nozzles of one or more printheads. An embodiment of a manufacturing apparatus print assembly, a manufacturing apparatus including a print assembly, and a method of use thereof will now be described in more detail with reference to the accompanying drawings. It should be understood that the embodiments of the manufacturing apparatus shown and described herein may be configured and operable to build three-dimensional and / or non-three-dimensional objects or parts.

[0009] Ranges can be expressed herein as from "about" one particular value, and / or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values ​​are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. The beginning and end points of a range each have a significant meaning in relation to the other point (the end point and the beginning point), and each have a significant meaning independently of the other point.

[0010] It should be noted that the terms "substantially" and "about" may be utilized herein to express the degree of inherent uncertainty that may result from any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to express the degree to which a quantitative representation may vary from the stated reference without resulting in a change in the basic functionality of the subject matter at issue.

[0011] Unless expressly stated otherwise, it is never intended that any method described herein be interpreted as requiring its steps to be performed in a particular order, or as requiring any particular orientation of any device. Thus, if a method claim does not actually recite an order to be followed for its steps, or if any device claim does not actually recite an order or orientation for individual components, or if it is specifically stated otherwise in the claim or description that the steps are to be limited to a particular order, or that no particular order or orientation for the components of the device is recited, no order or orientation is ever intended to be inferred at any point. This applies to any possible implicit basis for interpretation, including questions of logic regarding the arrangement of steps, operational flow, component order, or component orientation, plain meaning derived from grammatical organization or punctuation, and the number or type of embodiments described herein.

[0012] As used herein, the singular forms "a," "an," and the like include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "an" element includes aspects having two or more such elements unless the context clearly dictates otherwise.

[0013] The embodiments described herein are directed to manufacturing apparatus (e.g., additive manufacturing apparatus) and components for manufacturing apparatus, specifically print assemblies for depositing binders and other jettable materials. Various embodiments described herein may be implemented to perform unclogging operations for print assemblies. While the techniques developed and described herein relate to manufacturing, it is understood that aspects of the techniques may have application in related industries such as 2D printing.

[0014] Referring now to FIGURE 1, a manufacturing apparatus 100 is shown in accordance with one or more embodiments described herein. The manufacturing apparatus 100 may generally include a printhead assembly 102, a binder control system 104 for controlling a flow of binder to the printhead assembly 102, a gas control system 106 for controlling a flow of gas to the printhead assembly 102, a power supply 108 for powering the binder control system 104, the gas control system 106, and the printhead assembly 102, and a binder reservoir 110 for storing a supply of binder. The printhead assembly 102 includes a manifold assembly 112 and a printhead 114. Although only one printhead 114 is shown in FIGURE 1, it should be understood that the printhead assembly 102 may include any number of printheads, including multiple printheads 114.

[0015] With respect to the manifold assembly 112, the manifold assembly 112 includes an inlet or first manifold 116 and an outlet or second manifold 118. In embodiments, the first manifold 116 stores the binder before delivering it to the printheads 114. The second manifold 118 stores unused binder from the printheads 114. In some embodiments, the second manifold 118 receives the binder directly from the first manifold 116 as opposed to unused binder flowing through the printheads 114. In embodiments, the binder is a solvent-based binder.

[0016] The first manifold 116 includes a first gas inlet line 120 that places the first manifold 116 in fluid communication with the gas regulation system 106. The first gas inlet line 120 conducts gas from the gas regulation system 106 to the first manifold 116 and includes a first gas gauge 122 for detecting the pressure of the gas in the first manifold 116.

[0017] The first manifold 116 further includes a first binder inlet line 124 and a first binder outlet line 126 that communicates the first manifold 116 with the binder control device 104. The first binder inlet line 124 leads from the binder control device 104 and thus the binder tank 110 to the first manifold 116. A first binder inlet valve 128 is provided in the first inlet line 124 to control the flow of binder to the first manifold 116. The first binder outlet line 126 allows the binder to flow out of the first manifold 116. Thus, the binder can flow from the outlet 110A of the binder tank 110, through the binder control device 104, through the first binder inlet line 124 and into the first manifold 116. Similarly, binder can exit the first manifold 116 through a first binder outlet line 126, return through the binder control device 104, and return to the inlet 110B of the binder tank 110. A first binder outlet valve 130 is provided in the first outlet line 126 to control the flow of binder out of the first manifold 116.

[0018] The first manifold 116 further includes a first upper float 132A and a first lower float 132B. The first upper float 132A and the first lower float 132B are configured to detect the level of binder in the first manifold 116. When the first upper float 132A detects that the binder level exceeds a predetermined upper threshold, the gas control system 106 is operated to increase the pressurization of gas in the first manifold 116, as discussed herein. Alternatively, when the first lower float 132B detects that the binder level falls below a predetermined lower threshold, the gas control system 106 is operated to reduce the pressure of gas in the first manifold 116.

[0019] Similarly, the second manifold 118 includes a second gas inlet line 134 that places the second manifold 118 in fluid communication with the gas regulation system 106. The second gas inlet line 134 conducts gas from the gas regulation system 106 to the second manifold 118 and includes a second gas gauge 136 for detecting the pressure of gas within the second manifold 118.

[0020] The second manifold 118 further includes a second binder inlet line 138 and a second binder outlet line 140 that communicates the second manifold 118 with the binder control device 104. The second binder inlet line 138 directs binder from the binder control device 104 and thus the binder tank 110 to the second manifold 118. A second binder inlet valve 142 is provided in the second binder inlet line 138 to control the flow of binder to the second manifold 118. The second binder outlet line 140 allows binder to flow out of the second manifold 118. Thus, binder can flow from the outlet 110A of the binder tank 110, through the binder control device 104, through the second binder inlet line 138 and into the second manifold 118. Similarly, the binder can exit the second manifold 118 through a second binder outlet line 140, return through the binder control device 104, and return to the inlet 110B of the binder tank 110. A second binder outlet valve 144 is provided in the second outlet line 140 to control the flow of binder out of the second manifold 118. In an embodiment, the second binder inlet line 138 merges with the first binder inlet line 124, and the second binder outlet line 140 merges with the first binder outlet line 126.

[0021] The second manifold 118 further includes a second upper float 146A and a second lower float 146B. The second upper float 146A and the second lower float 146B are configured to detect the level of binder in the second manifold 118. When the second upper float 146A detects that the level of binder exceeds a predetermined upper threshold, the gas control system 106 is operated to increase the gas pressure in the second manifold 118 as discussed herein. Alternatively, when the second lower float 146B detects that the level of binder falls below a predetermined lower threshold, the gas control system 106 is operated to reduce the gas pressure in the second manifold 118. Although not shown, it should be understood that a bypass line may be provided to place the first manifold 116 and the second manifold 118 in direct fluid communication with each other. The bypass line can allow binder to flow from the first manifold 116 to the second manifold 118 without having to flow through the printhead 114. This can be necessary to adjust the level of binder in either the first manifold 116 or the second manifold 118 without requiring additional binder to be specifically pumped from the binder reservoir 110 to the first manifold 116 or the second manifold 118.

[0022] The first manifold 116 is in fluid communication with the printheads 114 via a first manifold supply line 148, and the second manifold 118 is in fluid communication with the printheads 114 via a second manifold supply line 150. A first manifold supply line valve 152 is provided in the first manifold supply line 148 to control the flow of binder between the printheads 114 and the first manifold 116. A second manifold supply line valve 154 is provided in the second manifold supply line 150 to control the flow of binder between the printheads 114 and the second manifold 118. In an embodiment, binder flows from the first manifold 116 through the first manifold supply line 148 to the printheads 114, where the binder is dispensed from one or more nozzles of the printheads 114. Any unused binder then flows from the printheads 114 to the second manifold 118 via the second manifold supply line 150.

[0023] The flow of binder through the printhead 114 from the first manifold 116 to the second manifold 118 is due in part to the pressure in the first manifold 116 being greater than the pressure in the second manifold 118. For example, the pressure in the first manifold 116 may be between -150 mmH2O and -250 mmH2O, and the pressure in the second manifold 118 may be between -200 mmH2O and -300 mmH2O. More specifically, for example, the pressure in the first manifold 116 may be between -175 mmH2O and -225 mmH2O, and the pressure in the second manifold 118 may be between -225 mmH2O and -275 mmH2O. However, the nozzles of the printhead 114 may become clogged such that the printhead 114 may need to undergo a purging operation to clear the clogged nozzles. As described herein, the gas control system 106 may be operated to perform a purge operation such that the pressure in the first manifold 116 and the second manifold 118 may be repeatedly increased and decreased to clog the binder in the nozzles of the printhead 114. It should be understood that the pressures provided herein are gauge pressures, i.e., pressures relative to the environment surrounding the printhead assembly 102.

[0024] 2, a manufacturing system 180 for operating the binder control system 104, gas control system 106, power supply 108, binder reservoir 110, and printhead assembly 102, including manifold assembly 112 and printhead 114, and their individual components, may be provided as discussed in more detail herein. The manufacturing apparatus 180 may include an electronic control unit 182, network interface hardware 184, and communication paths 186 communicatively coupled to these components.

[0025] The electronic control unit 182 comprises a processor 188 and a non-transitory electronic memory 190 to which the various components are communicatively coupled. In some embodiments, the processor 188 and the non-transitory electronic memory 190 and / or other components are included within a single device. In other embodiments, the processor 188 and the non-transitory electronic memory 190 and / or other components may be distributed among multiple communicatively coupled devices. The electronic control unit 182 includes a non-transitory electronic memory 190 that stores a set of machine-readable instructions. The processor 188 executes the machine-readable instructions stored in the non-transitory electronic memory 190. The non-transitory electronic memory 190 may comprise a RAM, a ROM, a flash memory, a hard drive, or any device capable of storing machine-readable instructions such that the machine-readable instructions may be accessed by the processor 188. Thus, the manufacturing system 180 described herein may be implemented as hardware elements pre-programmed in any conventional computer programming language or as a combination of hardware and software components. The non-transitory electronic memory 190 may be implemented as one memory module or multiple memory modules.

[0026] In some embodiments, non-transitory electronic memory 190 contains instructions for performing functions of manufacturing system 180. The instructions can include instructions for operating binder control system 104, gas control system 106, power supply 108, binder reservoir 110, and printhead assembly 102, including manifold assembly 112 and printhead 114, and their individual components.

[0027] The processor 188 may be any device capable of executing machine-readable instructions. For example, the processor 188 may be an integrated circuit, a microchip, a computer, or any other computing device. The non-transitory electronic memory 190 and the processor 188 are coupled to a communication path 186 that provides signal interconnectivity between various components and / or modules of the manufacturing system 180. Thus, the communication path 186 may communicatively couple any number of processors to each other, allowing the modules coupled to the communication path 186 to operate in a distributed computing environment. Specifically, each of the modules may operate as a node that can transmit and / or receive data. As used herein, the term "communicatively coupled" means coupled components that can exchange data signals with each other, such as, for example, electrical signals through a conductive medium, electromagnetic signals through the air, optical signals through optical waveguides, etc.

[0028] 2, a communication path 186 communicatively couples a processor 188 and a non-transitory electronic memory 190 of the electronic control unit 182 to a number of other components of the manufacturing system 180. For example, the manufacturing system 180 shown in FIG. 2 includes a processor 188 and a non-transitory electronic memory 190 communicatively coupled to the binder control system 104, the gas control system 106, the power supply 108, the binder reservoir 110, the manifold assembly 112, and the print heads 114.

[0029] In some embodiments, the manufacturing system 180 includes network interface hardware 184 for communicatively coupling the manufacturing system 180 to a computing device over a network. The computing device may include, but is not limited to, a smart phone, a tablet, a personal media player, or any other electrical device including wireless communication capabilities. It should be understood that, if provided, the computing device may function to remotely provide user instructions to the electronic control unit 182 by wirelessly communicating with the electronic control unit 182 over a network. In an embodiment, the manufacturing system 180 may include manipulation devices that allow a user to control the operation of the binder control system 104, the gas control system 106, the power supply 108, the binder tank 110, the manifold assembly 112, and the print head 114. In some embodiments, the manipulation devices may be switches, toggles, buttons, or any combination of controls for providing user manipulation. The manipulation devices are coupled to the communication paths 186 such that the communication paths 186 communicatively couple the manipulation devices to other modules of the manufacturing system 180.

[0030] 3 and 4, the gas control system 106 includes a panel 200 and a number of various components attached to the panel 200 in any suitable manner, such as utilizing brackets and other fasteners. The components generally include a positive pressure vessel 202 for supplying a gas, such as an inert gas, to each of the first and second manifolds 116 and 118 of the manifold assembly 112, a negative pressure vessel 204 for drawing a gas, such as an inert gas, from each of the first and second manifolds 116 and 118 of the manifold assembly 112, a first pressure control valve 206 for controlling the pressure in the first manifold 116, and a second pressure control valve 208 for controlling the pressure in the second manifold 118. It will be appreciated that the positive pressure vessel 202 may be any suitable vessel configured to define a plenum chamber containing a gas at a positive pressure. It will be appreciated that the negative pressure vessel 204 may be any suitable vessel configured to define a vacuum chamber containing a gas at a negative pressure.

[0031] The first pressure control valve 206 and the second pressure control valve 208 control the amount of gas entering and leaving the first manifold 116 and the second manifold 118, respectively, by controlling the rate at which the gas flows through the first pressure control valve 206 and the second pressure control valve 208. In an embodiment, the first pressure control valve 206 and the second pressure control valve 208 are proportional valves. Prior to performing a purge operation of the manifold assembly 112 or during normal operation of the gas control system 106, the positive pressure vessel 202 is positively pressurized (pressurized), e.g., above 0 psi, and the negative pressure vessel 204 is negatively pressurized (pressurized), to provide a vacuum, i.e., below 0 psi. More specifically, for example, the positive pressure vessel 202 may be positively pressurized to a pressure of 10 psi or more and 20 psi or less, and the negative pressure vessel 204 may be negatively pressurized to a pressure of -10 psi or more and -15 psi or less relative to atmosphere. However, after a purge operation in which the positive pressure vessel 202 releases gas into the first and second manifolds 116 and 118 and the negative pressure vessel 204 collects gas, the positive pressure vessel 202 and the negative pressure vessel 204 may be depressurized, i.e., the pressure within the positive pressure vessel 202 and the negative pressure vessel 204 may be at 0 psi. Thus, as discussed in more detail herein, the positive pressure vessel 202 and the negative pressure vessel 204 must be recalibrated from a depressurized state to a calibrated state in order to perform a subsequent purge operation or to continue normal operation.

[0032] In an embodiment, the gas control system 106 further includes a first positive pressure valve 210, a controlled first manifold valve 212, a first negative pressure valve 214, and a controlled second manifold valve 216. The first positive pressure valve 210 is positionable between a first open state, a second open state, and a closed state. When the first positive pressure valve 210 is in the closed state, gas may be prevented from flowing from the outlet 202B of the positive pressure vessel 202 through the first positive pressure valve 210.

[0033] When the first positive pressure valve 210 is in a first open state, gas from the positive pressure vessel 202 is allowed to flow through the first positive pressure valve 210 and is distributed to both the controlled side first manifold valve 212 and the controlled side second manifold valve 216 via the first positive pressure distributor 218. The first positive pressure distributor 218 receives gas from the positive pressure vessel 202 via the first positive pressure valve 210 and redirects the gas to the controlled side first manifold valve 212 and the controlled side second manifold valve 216. In an embodiment, the first positive pressure distributor 218 may include a controllable valve mechanism to control the amount of gas flowing to either or both of the controlled side first manifold valve 212 and the controlled side second manifold valve 216. In other embodiments, the first positive pressure distributor 218 may be fixed such that gas is distributed evenly to the controlled side first manifold valve 212 and the controlled side second manifold valve 216.

[0034] When the first positive pressure valve 210 is in the second open state, gas from the positive pressure vessel 202 is permitted to flow through the first positive pressure valve 210 and distributed to both the first pressure control valve 206 and the second pressure control valve 208 via the second positive pressure distributor 220. The second positive pressure distributor 220 receives gas from the positive pressure vessel 202 via the first positive pressure valve 210 and redirects the gas to the first pressure control valve 206 and the second pressure control valve 208. Similar to the first positive pressure distributor 218, in embodiments, the second positive pressure distributor 220 may include a controllable valve function to control the amount of gas to either or both of the first pressure control valve 206 and the second pressure control valve 208. In other embodiments, the second positive pressure distributor 220 may be fixed such that gas is distributed evenly to the first pressure control valve 206 and the second pressure control valve 208. As described in more detail herein, the first pressure control valve 206 and the second pressure control valve 208 control the amount of gas that is directed from the positive pressure vessel 202 to the first manifold 116 and the second manifold 118 .

[0035] The controlled first manifold valve 212 is positionable between a first open state, a second open state, and a closed state. When the controlled first manifold valve 212 is in the closed state, gas provided to the first manifold 116 by the positive pressure vessel 202 or drawn from the first manifold 116 by the negative pressure vessel 204 is prohibited from flowing through the controlled first manifold valve 212. When the controlled first manifold valve 212 is in the first open state, gas provided to the first manifold 116 by the positive pressure vessel 202 or drawn from the first manifold 116 by the negative pressure vessel 204 is allowed to flow through the controlled first manifold valve 212. More specifically, when the control-side first manifold valve 212 is in a first open state, gas provided by the first positive pressure valve 210 can flow from the first positive pressure valve 210 through the control-side first manifold valve 212 to the printhead-side first manifold valve 222. When the control-side first manifold valve 212 is in a second open state, gas is directed through the control-side first manifold valve 212 to the first pressure control valve 206. However, when the printhead-side first manifold valve 222 is positioned in a closed state, gas is prohibited from flowing through the printhead-side first manifold valve 222 to or from the first manifold 116.

[0036] Similarly, the control side second manifold valve 216 is positionable between a first open state, a second open state, and a closed state. When the control side second manifold valve 216 is in the closed state, gas provided to the second manifold 118 by the positive pressure vessel 202 or drawn from the second manifold 118 by the negative pressure vessel 204 is prohibited from flowing through the control side second manifold valve 216. When the control side second manifold valve 216 is in the first open state, gas provided to the second manifold 118 by the positive pressure vessel 202 or drawn from the second manifold 118 by the negative pressure vessel 204 is allowed to flow through the control side second manifold valve 216. More specifically, when the control-side second manifold valve 216 is in a first open state, gas provided by the first positive pressure valve 210 can flow from the first positive pressure valve 210 through the control-side second manifold valve 216 to the printhead-side second manifold valve 224. When the control-side second manifold valve 216 is in a second open state, gas is directed through the control-side second manifold valve 216 to the second pressure control valve 208. However, when the printhead-side second manifold valve 224 is positioned in a closed state, gas is prohibited from flowing to or from the second manifold 118 through the printhead-side second manifold valve 224.

[0037] Additionally, the first negative pressure valve 214 is positionable between an open state and a closed state. When the first negative pressure valve 214 is in a closed state, gas may be prevented from flowing through the first negative pressure valve 214 to the inlet 204A of the negative pressure vessel 204.

[0038] When the first negative pressure valve 214 is in an open state, gas, i.e., a secondary flow of gas, can flow through the first negative pressure valve 214, for example, from a negative pressure distributor 226. The negative pressure distributor 226 receives gas flowing from each of the first and second pressure control valves 206 and 208, which are received from the first and second manifolds 116 and 118, respectively. As discussed in more detail herein, the first and second pressure control valves 206 and 208 control the amount of gas drawn from the first and second manifolds 116 and 118 and directed to the negative pressure vessel 204 during a vacuum recovery mode or a normal operating mode.

[0039] In an embodiment, the gas control system 106 includes a positive pressure gauge 228 through which gas flows from the positive pressure vessel 202 to the first positive pressure valve 210. A positive pressure sensor 230 is in fluid communication with the positive pressure gauge 228 to detect the flow rate of gas through the positive pressure gauge 228. In some embodiments, during a power outage or complete system shutdown, the positive pressure gauge 228 can be operated to direct all gas from the positive pressure vessel 202 to an external gas vessel 232 to depressurize the gas control system 106. An external valve 234 may be provided to allow gas flow from the positive pressure gauge 228 to the external gas vessel 232.

[0040] Similarly, in an embodiment, the gas control system 106 also includes a negative pressure gauge 236. Gas flows through the negative pressure gauge 236 from the first negative pressure valve 214 to the negative pressure vessel 204. A negative pressure sensor 238 is in fluid communication with the negative pressure gauge 236 and detects the flow rate of gas through the negative pressure gauge 236.

[0041] The components described above control the gas flow between each of the positive pressure vessel 202 and the negative pressure vessel 204 and the manifold. However, as discussed herein, the positive pressure vessel 202 and the negative pressure vessel 204 need to be recalibrated after a purge operation from a reduced pressure state to a calibration state such that the positive pressure vessel 202 contains gas at a positive pressure greater than 0 psi and the negative pressure vessel 204 is reduced pressure to have a negative pressure / vacuum, i.e., less than 0 psi. Thus, the following components described herein are utilized to calibrate both the positive pressure vessel 202 and the negative pressure vessel 204 from a reduced pressure state to a calibration state.

[0042] In an embodiment, the gas control system 106 further includes a second positive pressure valve 240 for allowing gas to flow into the positive pressure vessel 202, such as during a cleaning operation or when calibrating the positive pressure vessel 202 back to a calibrated state. The second positive pressure valve 240 is positionable between an open state and a closed state. When the second positive pressure valve 240 is in an open state, gas can flow into the inlet 202A of the positive pressure vessel 202. When the second positive pressure valve 240 is in a closed valve state, gas is prohibited from flowing into the inlet 202A of the positive pressure vessel 202. Similarly, the gas control system 106 further includes a second negative pressure valve 242, which allows gas to flow from the outlet 204B of the negative pressure vessel 204 into the outlet 204B of the negative pressure vessel 204, such as during a cleaning operation, to create a vacuum in the negative pressure vessel 204 and to calibrate the negative pressure vessel 204 back to a calibrated state. The second negative pressure valve 242 is positionable between an open state and a closed state. When the second negative pressure valve 242 is in an open state, gas can flow through the second negative pressure valve 242, for example, to or from the outlet 204B of the negative pressure vessel 204. When the second negative pressure valve 242 is in a closed valve state, gas is prohibited from flowing to the outlet 204B of the negative pressure vessel 204.

[0043] After a purging operation, discussed in more detail herein, when both the positive pressure vessel 202 and the negative pressure vessel 204 are at reduced pressure, gas may be redistributed from the negative pressure vessel 204 to the positive pressure vessel 202 to calibrate the positive pressure vessel 202 and the negative pressure vessel 204 to their respective calibration states, such that the positive pressure vessel 202 is positively pressurized and the negative pressure vessel 204 is negatively pressurized. In an embodiment, as discussed in more detail herein, the gas control system 106 may include a dual piston assembly 244, a compressed air tank 246, a first piston valve 248, and a second piston valve 250. The dual piston assembly 244 operates to draw gas from the outlet 204B of the negative pressure vessel 204 and direct the gas to the inlet 202A of the positive pressure vessel 202. More specifically, in an embodiment, the dual piston assembly 244 includes a piston and operates by repeatedly alternating the piston between a first position and a second position to draw gas from the compressed air tank 246 and generate a suction force that directs the gas toward the positive pressure vessel 202. Although the dual piston assembly 244 is shown in the same position in FIGS. 6-11, it should be understood that when the dual piston assembly 244 is actuated, the piston is actuated repeatedly. The dual piston assembly 244 may be operated to circulate gas between the positive pressure vessel 202 and the negative pressure vessel 204 to achieve a completely closed gas circulation, thereby reducing the degree of risk to the operator.

[0044] The first piston valve 248 may be positionable between an open state and a closed state. When the first piston valve 248 is in an open state, compressed air from the compressed air tank 246 may be delivered to the dual piston assembly 244 to actuate the dual piston 244. When the first piston valve 248 is in a closed state, compressed air may not be delivered to the dual piston assembly 244. When the second piston valve 250 is in an open state, gas is allowed to enter the dual piston assembly 244 from the negative pressure vessel 204, enter the dual piston assembly 244, and exit the dual piston assembly 244 to be delivered to the positive pressure vessel 202. When the second piston valve 250 is in a closed position, gas is prohibited from entering the dual piston assembly 244 from the negative pressure vessel 204 and gas is prohibited from being delivered from the dual piston assembly 244 to the positive pressure vessel 202.

[0045] In another embodiment, the gas control system 106 includes an external gas supply source 252 for delivering gas to the positive pressure vessel 202 independent of gas drawn from the negative pressure vessel 204. The external gas supply source 252 may be configured to deliver gas to both the positive pressure vessel 202 and the negative pressure vessel 204, such as during a cleaning operation. In this embodiment, as described in more detail herein, the external gas supply source 252 supplies gas to the positive pressure vessel 202 and the negative pressure vessel 204 via an external gas supply distributor 254. The external gas supply distributor 254 receives gas from the external gas source 252 and redirects the gas to both the positive pressure vessel 202 and the negative pressure vessel 204. In an embodiment, the external gas supply distributor 254 may include a controllable valve mechanism for controlling the amount of gas flowing to either or both of the positive pressure vessel 202 and the negative pressure vessel 204. In other embodiments, an external gas supply distributor 254 may be fixed such that gas is evenly distributed to the positive pressure vessel 202 and the negative pressure vessel 204 .

[0046] In other embodiments, the gas control system 106 may include a venturi device 256 configured to receive gas or other fluid from the external gas source 252 and draw gas from the negative pressure vessel 204 to generate a negative pressure within the negative pressure vessel 204, thereby returning the negative pressure vessel 204 to a calibrated state. The gas control system 106 may include a first venturi valve 258 disposed between the external gas source 252 and the venturi device 256 and positionable between an open position and a closed position. When the first venturi valve 258 is in the open position, the fluid flow from the external gas source 252 may flow into the venturi device 256. When the first venturi valve 258 is in the closed position, the fluid flow from the external gas source 252 is prohibited from entering the venturi device 256. In an embodiment, the gas control system 106 further includes a second venturi valve 260 disposed between the venturi device 256 and the negative pressure vessel 204. The second venturi valve 260 is configured to allow gas to flow in only one direction between the venturi device 256 and the vacuum vessel 204. Specifically, the second venturi valve 260 allows gas to be drawn from the vacuum vessel 204 and supplied to the venturi device 256, but prevents gas from flowing back into the vacuum vessel 204.

[0047] The gas control system 106 is operable between a number of modes, such as, for example, a positive pressure purge mode during a purge operation, a negative pressure purge mode or a vacuum recovery mode during a purge operation, a normal positive pressure mode during normal operation, a normal negative pressure mode during normal operation, a calibration mode, and a cleaning mode.

[0048] As described herein, the manufacturing system 180 includes an electronic control unit 182. It should be appreciated that the electronic control unit 182 is configured to operate the individual components of the gas control system 106. For example, the electronic control unit 182 is responsible for controlling at least the first positive pressure valve 210, the control side first manifold valve 212, the first negative pressure valve 214, the control side second manifold valve 216, the first pressure control valve 206, and the second pressure control valve 208 among various operating positions and states.

[0049] 5, gas flow during a positive pressure purge mode of the purge operation is shown in solid lines. Specifically, the gas controller 106 executes a purge operation when it is determined that the printhead 114 of the printhead assembly 102 requires purging, such as when a clog is detected in one or more nozzles of the printhead 114. The purge operation includes a positive pressure purge mode and a negative pressure purge mode, also referred to herein as a vacuum recovery mode. During the positive pressure purge mode of the purge operation, gas from the positive pressure container 202 is released into the first manifold 116 and the second manifold 118. More specifically, during the positive pressure purge mode, the first positive pressure valve 210 is positioned in a first open state in which gas is directed through the first positive pressure distributor 218 to both the controlled first manifold valve 212 and the controlled second manifold valve 216. In the positive pressure purge mode, the control-side first manifold valve 212 and the control-side second manifold valve 216 are both positioned in a first open state to allow gas to flow to the print head-side first manifold valve 222 and the print head-side second manifold valve 224. The print head-side first manifold valve 222 and the print head-side second manifold valve 224 are then both positioned in an open state to allow gas to flow into the first manifold 116 and the second manifold 118, respectively. By allowing gas to flow unrestricted from the positive pressure vessel 202 to both the first manifold 116 and the second manifold 118, pressure increases in the first manifold 116 and the second manifold 118, forcing additional binder into the print head 114. Additionally, gas can bypass the first pressure control valve 206 and the second pressure control valve 208.

[0050] 6, gas flow during a negative pressure purge mode or vacuum recovery mode of the purge operation is shown in solid lines. After the positive pressure purge mode is completed, the gas control system 106 is operated to perform the negative pressure purge mode or vacuum recovery mode such that the positive pressure vessel 202 is depressurized and gas is delivered to the first manifold 116 and the second manifold 118. As described above, during the positive pressure purge mode, the print head side first manifold valve 222, the print head side second manifold valve 224, the control side first manifold valve 212, and the control side second manifold valve 216 are each in an open state. However, in the negative pressure purge mode, the control side first manifold valve 212 and the control side second manifold valve 216 are positioned in a second open state such that gas from the first manifold 116 and the second manifold 118 can be directed to the first pressure control valve 206 and the second pressure control valve 208, respectively. The first negative pressure valve 214 is then positioned in an open state such that the vacuum within the negative pressure vessel 204 draws gas from each of the first and second manifolds 116 and 118 through the first and second pressure control valves 206 and 208. During the negative pressure purge mode, the first and second pressure control valves 206 and 208 may be configured to allow a complete unrestricted flow of gas from the first and second manifolds 116 and 118 to the negative pressure vessel 204. It should be appreciated that when in the positive pressure purge mode, gas flows through the first and second pressure control valves 206 and 208 to not provide a direct flow of gas to the first and second manifolds 116 and 118, further eliminating the need for additional gas lines connected to the first and second pressure control valves 206 and 208.

[0051] It should be appreciated that during a purge operation, the gas control system 106 may repeatedly alternate between positive and negative pressure purge states a predetermined number of times within close intervals of each other to purge the print head 114.

[0052] 7, gas flow during normal positive pressure mode of normal operation is shown. During normal operation of the gas control device 106, gas is provided to the first and second manifolds 116, 118 to maintain the binder in the first and second manifolds 116, 118 within a predetermined range. This differs from the positive pressure purge mode where an increased amount of gas is provided to the first and second manifolds 116, 118 to remove clogging. As mentioned above, the level of binder in the first manifold 116 is determined by the first upper float 132A and the first lower float 132B. Similarly, the level of binder in the second manifold 118 is determined by the second upper float 146A and the second lower float 146B. When the level of binder in either the first manifold 116 or the second manifold 118 exceeds a predetermined level, the pressure in the corresponding first manifold 116 or second manifold 118 increases. For example, when the level of binder in both the first manifold 116 and the second manifold 118 exceeds a predetermined level, the pressure in both the first manifold 116 and the second manifold 118 increases by directing gas from the positive pressure vessel 202 to the first manifold 116 and the second manifold 118. More specifically, in this example, the first positive pressure valve 210 is positioned in a second open state, allowing gas to flow from the positive pressure vessel 202. Thereafter, the gas, i.e., the primary gas flow that diverges to form a first gas flow (first gas flow) and a second gas flow (second gas flow), is directed through the first positive pressure distributor 218 to both the first pressure control valve 206 and the second pressure control valve 208. The first pressure control valve 206 and the second pressure control valve 208 are each operated to control the amount of gas allowed to flow into the first manifold 116 and the second manifold 118 based on the level of binder detected within each of the first manifold 116 and the second manifold 118.For example, if the binder level is higher in the first manifold 116 compared to the binder level in the second manifold 118, the first pressure control valve 206 may allow a greater amount of gas to flow to the first manifold 116 compared to the amount of gas allowed to flow to the second manifold 118 by the second pressure control valve 208. During normal positive pressure mode, the control-side first manifold valve 212 and the control-side second manifold valve 216 are both positioned in a second open state, allowing gas to flow from the first pressure control valve 206 and the second pressure control valve 208. Additionally, the printhead-side first manifold valve 222 and the printhead-side second manifold valve 224 are both positioned in an open state to allow gas to enter the first manifold 116 and the second manifold 118, respectively.

[0053] 8, gas flow during a normal negative pressure mode of normal operation is shown. It should be understood that the direction of gas flow during a normal negative pressure mode of normal operation is the same as the direction of gas flow during a negative pressure purge mode of purge operation. During normal operation of the gas control device 106, while in a normal negative pressure state, gas is drawn into the first and second manifolds 116, 118 to maintain the binder in the first and second manifolds 116, 118 within a predetermined range. This differs from the negative pressure purge mode, where an increased amount of gas is drawn from the first and second manifolds 116, 118 to clear clogging. If it is determined that the binder level detected in the first or second manifold 116, 118 is below the predetermined range, the pressure of the corresponding first or second manifold 116, 118 must be reduced to allow the binder level to rise. For example, if the binder levels in both the first manifold 116 and the second manifold 118 fall below a predetermined level, the pressure in both the first manifold 116 and the second manifold 118 is reduced by drawing gas from the first manifold 116 and the second manifold 118 by the negative pressure container 204. During the normal negative pressure mode, the control-side first manifold valve 212 and the control-side second manifold valve 216 are both positioned in a second open state to allow gas to flow to the first pressure control valve 206 and the second pressure control valve 208. Additionally, the printhead-side first manifold valve 222 and the printhead-side second manifold valve 224 are both positioned in an open state to allow gas to be drawn from the first manifold 116 and the second manifold 118, respectively. More specifically, in this example, the first negative pressure valve 214 is positioned in an open state to allow gas to flow into the negative pressure vessel 204 caused by the negative pressure or vacuum created within the negative pressure vessel 204. The first pressure control valve 206 and the second pressure control valve 208 are then configured to direct gas flow from the first manifold 116 and the second manifold 118 through the negative pressure distributor 226 to the negative pressure vessel 204.More specifically, the first pressure control valve 206 and the second pressure control valve 208 operate to control the amount of gas that can be drawn from the first manifold 116 and the second manifold 118 based on the level of binder detected within each of the first manifold 116 and the second manifold 118. For example, if the level of binder in the first manifold 116 is higher compared to the level of binder in the second manifold 118, the first pressure control valve 206 may allow less gas to be drawn from the first manifold 116 compared to the amount of gas that can be drawn from the second manifold 118 by the second pressure control valve 208.

[0054] It should be understood that the gas control system 106 can alternate between a normally positive pressure mode and a normally negative pressure mode at any time to regulate the pressure in the first manifold 116 and the second manifold 118. Additionally, it should be understood that in embodiments, the gas control system 106 can be operated to allow gas to flow from the positive pressure vessel 202 to one of the first manifold 116 or the second manifold 118 while gas is being drawn from the other of the first manifold 116 or the second manifold 118 by the negative pressure vessel 204.

[0055] 9, gas flow during an embodiment of a calibration mode is shown. As described herein, after a purge operation is performed, the positive pressure vessel 202 and the negative pressure vessel 204 are depressurized. Specifically, the pressure in the positive pressure vessel 202 and the negative pressure vessel 204 is depleted to 0 psi. Therefore, before another purge operation can be performed, the positive pressure vessel 202 and the negative pressure vessel 204 must be returned to a calibrated state such that the positive pressure vessel 202 has a positive pressure and the negative pressure vessel 204 has a negative pressure or is maintained at a vacuum. In an embodiment, during the calibration mode, gas in the negative pressure vessel 204 can be transferred to the positive pressure vessel 202 to create a vacuum in the negative pressure vessel 204 and positively pressurize the positive pressure vessel 202. More specifically, as described herein, the dual piston assembly 244 can be operated to draw gas from the negative pressure vessel 204 and return gas into the positive pressure vessel 202. At this time, both the second positive pressure valve 240 and the second negative pressure valve 242 are in an open state to allow gas to flow through. Additionally, the first piston valve 248 is positioned in an open state to allow air from the compressed air tank 246 to be supplied to and actuate the dual piston assembly 244. The second piston valve 250 is also positioned in an open state to allow gas to flow into and out of the dual piston assembly 244. The dual piston assembly 244 is actuated until the positive pressure vessel 202 and the negative pressure vessel 204 are pressurized back to their respective calibration states, which may be detected by the positive pressure sensor 230 and the negative pressure sensor 238, respectively.

[0056] 10, gas flow during another embodiment of the calibration mode is shown. Rather than transferring gas from the negative pressure vessel 204 to the positive pressure vessel 202 as discussed in the above embodiment of the calibration mode, an external gas can be separately provided to the positive pressure vessel 202 and used to withdraw gas from the negative pressure vessel 204. Specifically, the second positive pressure valve 240 can be positioned in an open state and the external gas source 252 can be operated to deliver gas into the positive pressure vessel 202 through the external gas supply distributor 254. It should be understood that in this embodiment, the external gas supply distributor 254 is configured to direct gas flow only to the positive pressure vessel 202 and not to the negative pressure vessel 204. Alternatively, the second negative pressure valve 242 can be configured not to receive gas from the external gas supply distributor 254. In an embodiment, the positive pressure sensor 230 can detect when the positive pressure vessel 202 is returned to the calibrated state, and in response, the second positive pressure valve 240 can be positioned in a closed state to prevent additional gas from entering the positive pressure vessel 202. Additionally, the external gas supply 252 can be operated to direct a gas flow to the venturi device 256 when the first venturi valve 258 is in an open state. The second negative pressure valve 242 and the second venturi valve 260 are then positioned in an open state such that the gas flow through the venturi device 256 draws gas from the negative pressure vessel 204. In an embodiment, the negative pressure sensor 238 can detect when the negative pressure vessel 204 is returned to the calibrated state, and in response, the second negative pressure valve 242 can be positioned in a closed state to prevent additional gas from being drawn from the negative pressure vessel 204. The external gas supply 252 can then be shut off.

[0057] 11, gas flow during a cleaning mode is shown. In an embodiment, it may be necessary to supply gas to both the positive pressure vessel 202 and the negative pressure vessel 204 to ensure there are no leaks in the gas regulation system 106 or to inactivate the entire gas regulation system 106. Thus, the external gas supply 252 operates to supply gas to both the positive pressure vessel 202 and the negative pressure vessel 204. More specifically, the external gas supply distributor 254 is configured to direct gas flow to both the positive pressure vessel 202 and the negative pressure vessel 204. In addition, the second positive pressure valve 240 and the second negative pressure valve 242 are both positioned in an open position to allow gas from the external gas supply 252 to enter the positive pressure vessel 202 and the negative pressure vessel 204. After the cleaning mode is completed, the external gas supply 252 may be deactivated.

[0058] From the above, it should be appreciated that a manufacturing apparatus is defined herein that includes a printhead assembly including a first manifold, a second manifold, and one or more printheads, a binder control system, a gas control system, a power supply, and a binder reservoir. The power supply provides power to the binder control system, the gas control system, and the printhead assembly. The binder control system controls the flow of binder from the binder reservoir to each of the first and second manifolds. The gas control system controls the flow of gas from an external gas source to each of the first and second manifolds. During a purge operation, gas can be rapidly circulated between the gas control system and the manifolds to purge clogged nozzles of one or more printheads.

[0059] This provides several advantages, for example, improved safety, printhead stability, robustness, and controllability, as well as reduced cost and response time due to rapid pressurization and purging. More specifically, the positive and negative pressure vessels supply the necessary gas pressures to the printhead required for fluid back-purging and vacuum-based meniscus control. This also allows for ultra-precise printhead gas pressure control, achieved by the first and second pressure control valves. The piston assembly allows gas to flow to the positive pressure vessels in a completely closed gas circuit.

[0060] Further aspects of the embodiments described herein are provided by the following caveats:

[0061] (Appendix 1) A positive pressure vessel; A negative pressure vessel; a first pressure control valve configured to control a first flow of gas between a first manifold of the printhead assembly; a second pressure control valve configured to control a second flow of gas between the second manifold of the printhead assembly and a second manifold; Including, during a positive pressure normal mode, a primary flow of gas forming the first flow of gas and the second flow of gas flows from the positive pressure vessel through each one of the first pressure control valve and the second pressure control valve to the first manifold and the second manifold; during a positive pressure purge mode, the first flow of gas and the second flow of gas from the positive pressure vessel bypass the first pressure control valve and the second pressure control valve to flow to the first manifold and the second manifold. Gas control system.

[0062] (Appendix 2) During a negative pressure purge mode and a negative pressure normal mode, the first flow of gas and the second flow of gas are drawn from the first manifold and the second manifold through respective ones of the first pressure control valve and the second pressure control valve and into the negative pressure vessel. Appendix 1 Gas Control System.

[0063] (Appendix 3) The positive pressure vessel is calibrated to a positive pressure of 10 psi or more and 20 psi or less; The negative pressure container is calibrated to a negative pressure of -10 psi or less and -15 psi or more. Gas control systems of Annex 1 or Annex 2.

[0064] (Appendix 4) a first positive pressure valve positionable between a first open condition, a second open condition, and a closed condition; a controlled first manifold valve positionable between a first open condition, a second open condition, and a closed condition for directing the primary flow of gas toward the first manifold; Further comprising: when the first positive pressure valve is in the first open state, the primary flow of gas from the positive pressure vessel is directed to the control side first manifold valve; When the first positive pressure valve is in the second open state, the primary flow of gas from the positive pressure vessel is directed to the first pressure control valve and the second pressure control valve. A gas control system according to any one of Appendix 1 to Appendix 3.

[0065] (Appendix 5) a first vacuum valve positionable between an open and a closed position; Further comprising: When the first vacuum valve is in the open state, a secondary flow of gas can be drawn from the first pressure control valve and the second pressure control valve into the vacuum vessel. A gas control system according to any one of Appendix 1 to Appendix 4.

[0066] (Appendix 6) a controlled second manifold valve positionable between a first open condition, a second open condition, and a closed condition; Further comprising: when the controlled second manifold valve is in the first open state, the primary flow of gas from the positive pressure vessel is permitted to flow through the controlled second manifold valve to the second manifold; When the control side second manifold valve is in the second open state, a secondary flow of gas is allowed to flow between the second manifold and the second pressure control valve. A gas control system according to any one of Appendix 1 to Appendix 5.

[0067] (Appendix 7) a positive pressure sensor configured to detect a pressure in the positive pressure vessel; a negative pressure sensor configured to detect the pressure of the negative pressure vessel; an electronic control unit configured to receive data from the positive pressure sensor and the negative pressure sensor; The gas control system of any one of appendix 1 to appendix 6, further comprising:

[0068] (Appendix 8) a dual piston assembly configured to draw gas from the negative pressure vessel and return the gas to the positive pressure vessel to establish a negative pressure in the negative pressure vessel and a positive pressure in the positive pressure vessel; The gas control system of any one of appendix 1 to appendix 7, further comprising:

[0069] (Appendix 9) an external gas supply in direct fluid communication with said positive pressure vessel; a venturi device in fluid communication with the external gas supply; Further comprising: During a calibration mode, the external gas supply directs gas from the external gas supply to the positive pressure vessel to establish a positive pressure within the positive pressure vessel; During the calibration mode, the external gas supply directs gas from the external gas supply to the venturi device; the venturi device is configured to draw gas from the vacuum vessel to establish a vacuum in the vacuum vessel; A gas control system according to any one of appendix 1 to appendix 8.

[0070] (Appendix 10) A printhead assembly including a first manifold, a second manifold, and a printhead, the first manifold and the second manifold direct a first flow of binder to and from the printhead; the first manifold and the second manifold each include a float for detecting a level of binder in each one of the first manifold and the second manifold; A print head assembly; a binder control system for controlling a second flow of binder to the first manifold and the second manifold; The gas control system of claim 1; 4. A manufacturing device comprising:

[0071] (Appendix 11) during a negative pressure normal mode, when the float detects a binder level below a predetermined threshold, the negative pressure vessel draws gas from the first manifold and the second manifold through one of each of the first pressure control valve and the second pressure control valve. The manufacturing equipment of appendix 10.

[0072] (Appendix 12) The floats of each of the first manifold and the second manifold are an upper float configured to detect when the level of one of the binders in each of the first and second manifolds exceeds a predetermined upper threshold; a lower float configured to detect when the level of one of the binders in each of the first and second manifolds falls below a lower predetermined threshold; 12. The manufacturing apparatus of claim 10 or 11,

[0073] (Appendix 13) During a negative pressure purge mode and a negative pressure normal mode, gas is drawn from the first manifold and the second manifold through a respective one of the first pressure control valve and the second pressure control valve into the negative pressure vessel. Manufacturing equipment of appendix 13.

[0074] (Appendix 14) the positive pressure vessel is calibrated to a positive pressure to deliver gas to the first manifold and the second manifold; the negative pressure vessel is calibrated to a negative pressure to draw gas from the first manifold and the second manifold; The manufacturing apparatus according to any one of appendix 10 to appendix 13.

[0075] (Appendix 15) a dual piston assembly configured to draw gas from the negative pressure vessel and return the gas to the positive pressure vessel during a calibration mode to establish a negative pressure in the negative pressure vessel and a positive pressure within the positive pressure vessel; The manufacturing apparatus according to any one of claims 10 to 14, further comprising:

[0076] (Appendix 16) an external gas supply in direct fluid communication with said positive pressure vessel; a venturi device in fluid communication with the external gas supply; Further comprising: During a calibration mode, the external gas supply directs gas to the positive pressure vessel to establish a positive pressure within the positive pressure vessel; During the calibration mode, the external gas supply directs gas to the venturi device; the venturi device is configured to draw gas from the vacuum vessel to establish a vacuum in the vacuum vessel; The manufacturing apparatus according to any one of appendix 10 to appendix 15.

[0077] (Appendix 17) Adjust the positive pressure container of the gas control system to a positive pressure, pressurizing a negative pressure vessel of the gas control system to a negative pressure to create a vacuum in the negative pressure vessel; Transferring gas between the positive pressure vessel and the negative pressure vessel to achieve a completely closed gas circuit; operating said gas control system to perform normal operation to maintain binder levels in the first and second manifolds; the normal operation includes a normal positive pressure normal mode in which gas from the positive pressure vessel is directed to a first manifold via a first pressure control valve and gas from the positive pressure vessel is directed to a second manifold via a second pressure control valve; operating the gas control system to perform a purge operation to unclog nozzles of a print head; the purge operation includes a positive pressure purge mode in which gas from the positive pressure vessel is permitted to flow to the first manifold and the second manifold while bypassing the first pressure control valve and the second pressure control valve. method.

[0078] (Appendix 18) drawing gas from the first manifold and the second manifold through respective ones of the first pressure control valve and the second pressure control valve into the negative pressure vessel during a negative pressure purge mode of purging operation and a normal negative pressure mode of normal operation; the gas is an inert gas, the binder in the first manifold and the second manifold is a solvent-based binder; Method according to Appendix 17 or Appendix 18.

[0079] (Appendix 19) calibrating the positive pressure vessel to a positive pressure prior to the purge operation and the normal operation and allowing gas to be delivered to the first manifold and the second manifold; calibrating the negative pressure vessel to a negative pressure prior to the purge operation and the normal operation to allow gas to be drawn from the first manifold and the second manifold; Method according to Appendix 17 or Appendix 18.

[0080] (Appendix 20) During a calibration mode, actuating a dual piston assembly to draw gas from the negative pressure vessel and return the gas to the positive pressure vessel to establish a negative pressure in the negative pressure vessel and a positive pressure in the positive pressure vessel. 19. The method of any one of claims 17 to 19, further comprising:

[0081] While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications can be made without departing from the scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.

Claims

1. A positive pressure vessel (202); A negative pressure vessel (204); a first pressure control valve (206) configured to control a first flow of gas between a first manifold (116) of the printhead assembly (102); a second pressure control valve (208) configured to control a second flow of gas between a second manifold (118) of the printhead assembly (102); Including, During a positive pressure normal mode, a primary flow of gas forming the first flow of gas and the second flow of gas flows from the positive pressure vessel (202) through each one of the first pressure control valve (206) and the second pressure control valve (208) to the first manifold (116) and the second manifold (118); During a positive pressure purge mode, the first flow of gas and the second flow of gas from the positive pressure vessel (202) bypass the first pressure control valve (206) and the second pressure control valve (208) to flow to the first manifold (116) and the second manifold (118). Gas control system.

2. During a negative pressure purge mode and a negative pressure normal mode, the first flow of gas and the second flow of gas are drawn from the first manifold (116) and the second manifold (118) through respective ones of the first pressure control valve (206) and the second pressure control valve (208) into the negative pressure vessel (204). The gas control system of claim 1 .

3. The positive pressure vessel (202) is calibrated to a positive pressure of 10 psi or more and 20 psi or less; The negative pressure vessel (204) is calibrated to a negative pressure of -10 psi or less and -15 psi or more. The gas control system according to claim 1 or 2.

4. a first positive pressure valve (210) positionable between a first open state, a second open state, and a closed state; a controlled first manifold valve (212) positionable between a first open state, a second open state, and a closed state; Further comprising: when the first positive pressure valve (210) is in the first open state, the primary flow of gas from the positive pressure vessel (202) is directed to the controlled first manifold valve (212); when the first positive pressure valve (210) is in the second open state, the primary flow of gas from the positive pressure vessel (202) is directed to the first pressure control valve (206) and the second pressure control valve (208); The gas control system according to claim 1 or 2.

5. a first negative pressure valve (214) positionable between an open state and a closed state; Further comprising: when the first negative pressure valve (214) is in the open state, a secondary flow of gas can be drawn from the first pressure control valve (206) and the second pressure control valve (208) into the negative pressure vessel (204); The gas control system according to claim 1 or 2.

6. a controlled second manifold valve (216) positionable between a first open condition, a second open condition, and a closed condition; Further comprising: when the controlled second manifold valve (216) is in the first open state, the primary flow of gas from the positive pressure vessel (202) is permitted to flow through the controlled second manifold valve (216) to the second manifold (118); When the control side second manifold valve (216) is in the second open state, a secondary flow of gas is allowed to flow between the second manifold (118) and the second pressure control valve (208). The gas control system according to claim 1 or 2.

7. A printhead assembly (102) including a first manifold (116), a second manifold (118), and a printhead, the first manifold (116) and the second manifold (118) direct a first flow of binder to and from the printhead; the first manifold (116) and the second manifold (118) each include a float (132A, 132B, 146A, 146B) for detecting a level of binder in one of each of the first manifold (116) and the second manifold (118); A printhead assembly (102); a binder control system (104) for controlling a second flow of binder to the first manifold (116) and the second manifold (118); The gas control system of claim 1 ; A manufacturing apparatus (100).

8. During a negative pressure normal mode, when the float (132A, 132B, 146A, 146B) detects a binder level below a predetermined threshold, if the float that detected the binder level below the predetermined threshold corresponds to the first manifold (116), the negative pressure vessel (204) draws gas from the first manifold (116) through the first pressure control valve (206), and if the float that detected the binder level below the predetermined threshold corresponds to the second manifold (118), the negative pressure vessel (204) draws gas from the second manifold (118) through the second pressure control valve (208). The manufacturing apparatus (100) of claim 7.

9. The floats (132A, 132B, 146A, 146B) of each of the first manifold (116) and the second manifold (118) are an upper float (132A, 146A) configured to detect when the level of one of the binders in each of the first manifold (116) and the second manifold (118) exceeds a predetermined upper threshold; a lower float (132B, 146B) configured to detect when the level of one of the binders in each of the first manifold (116) and the second manifold (118) falls below a predetermined lower threshold; The manufacturing apparatus (100) of claim 7 or claim 8, comprising:

10. During a negative pressure purge mode and a negative pressure normal mode, gas is drawn from the first manifold (116) and the second manifold (118) through a respective one of the first pressure control valve (206) and the second pressure control valve (208) into the negative pressure vessel (204). The manufacturing apparatus (100) according to any one of claims 7 or 8.

11. a dual piston assembly (244) configured to draw gas from the negative pressure vessel (204) and return the gas to the positive pressure vessel (202) during a calibration mode to establish a negative pressure in the negative pressure vessel (204) and a positive pressure in the positive pressure vessel (202); The manufacturing apparatus (100) of claim 7 or claim 8, further comprising:

12. an external gas supply (252) in direct fluid communication with said positive pressure vessel (202); a venturi device (256) in fluid communication with the external gas supply (252); Further comprising: During a calibration mode, the external gas supply (252) directs gas to the positive pressure vessel (202) to establish a positive pressure in the positive pressure vessel (202); During the calibration mode, the external gas supply (252) directs gas to the venturi device (256); The venturi device (256) is configured to draw gas from the vacuum vessel (204) to establish a vacuum in the vacuum vessel (204). The manufacturing apparatus (100) according to claim 7 or claim 8.

13. Adjusting the positive pressure vessel (202) of the gas control system (106) to a positive pressure; adjusting the negative pressure vessel (204) of the gas control system (106) to a negative pressure to create a vacuum in the negative pressure vessel (204); Transferring gas between the positive pressure vessel (202) and the negative pressure vessel (204) to achieve a completely closed gas circuit; operating said gas control system (106) to perform normal operation to maintain binder levels in the first manifold (116) and the second manifold (118); the normal operation includes a normal positive pressure normal mode in which gas from the positive pressure vessel (202) is directed through a first pressure control valve (206) to a first manifold (116) and gas from the positive pressure vessel (202) is directed through a second pressure control valve (208) to a second manifold (118); operating the gas control system (106) to perform a purge operation to unclog nozzles of the print head (114); the purge operation includes a positive pressure purge mode in which gas from the positive pressure vessel (202) is permitted to flow to the first manifold (116) and the second manifold (118) while bypassing the first pressure control valve (206) and the second pressure control valve (208); method.

14. and drawing gas from the first manifold (116) and the second manifold (118) through respective ones of the first pressure control valve (206) and the second pressure control valve (208) into the negative pressure vessel (204) during a negative pressure purge mode of purging operation and a normal negative pressure mode of normal operation. The method of claim 13.

15. calibrating the positive pressure vessel (202) to a positive pressure prior to the purge operation and the normal operation and allowing gas to be delivered to the first manifold (116) and the second manifold (118); calibrating the negative pressure vessel (204) to a negative pressure prior to the purge operation and the normal operation to allow gas to be drawn from the first manifold (116) and the second manifold (118); The method according to claim 13 or claim 14.

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