Additive manufacturing device and environmental control method

Abstract

According to various embodiments, an additive manufacturing apparatus includes a process chamber enclosing a print head, a recoat head, and a linear motion stage to which the print head and recoat head are coupled. The print head and recoat head operate within the process chamber to build a three-dimensional object by depositing a build material and a binder material. The additive manufacturing apparatus further includes a condenser system fluidly coupled to the process chamber to receive a gas stream having a first vapor content from the process chamber and to provide the gas stream with a second vapor content to the process chamber. The second vapor content is less than the first vapor content. Additionally, the additive manufacturing apparatus includes a blower fluidly coupled to the process chamber and the condenser to flow the gas stream through a closed loop including the blower, the process chamber, and the condenser.

Description

[Technical field]

[0001] The present specification relates generally to additive manufacturing devices and methods of use thereof, and more particularly to additive manufacturing devices that include environmental systems and methods of use thereof. [Background technology]

[0002] Additive manufacturing devices can be utilized to "build" objects layer by layer from build materials such as organic or inorganic powders. Some build materials, such as chemically reactive powders, require an inert atmosphere for printing. Additionally, stable boundary conditions during additive manufacturing processes allow for repeatable processing. For example, fluctuations in temperature, humidity, oxygen content, particle content, as well as pressure and flow rates within the build area can affect the quality of the object and cause hazardous situations when chemically reactive powders are used. Summary of the Invention [Problem to be solved by the invention]

[0003] Therefore, there is a need for additive manufacturing equipment that can carefully control the environment within the build area. [Means for solving the problem]

[0004] A first embodiment A1 includes an additive manufacturing apparatus including a process chamber enclosing a print head, a recoat head, and a linear motion stage to which the print head and the recoat head are coupled, wherein the print head and the recoat head operate within the process chamber to build a three-dimensional object by depositing a build material and a binder material; a condenser system fluidly coupled to the process chamber to receive a gas stream having a first vapor content from the process chamber and to provide a gas stream having a second vapor content to the process chamber, the second vapor content being less than the first vapor content; and a blower fluidly coupled to the process chamber and the condenser system to flow the gas stream through a closed loop including the blower, the process chamber, and the condenser system.

[0005] A second aspect A2 includes the additive manufacturing apparatus of first aspect A1, further including a concentrator fluidly coupled to the condenser system and the process chamber.

[0006] A third aspect A3 comprises the additive manufacturing apparatus of first aspect A1 or second aspect A2, further comprising a VOC (volatile organic compound) sensor along a flow path of the gas stream through the closed loop.

[0007] A fourth aspect A4 comprises the additive manufacturing apparatus of any of the first aspect A1 to third aspect A3, further comprising a LEL (lower explosive limit) sensor along a flow path of the gas stream through the closed loop.

[0008] A fifth aspect A5 comprises an additive manufacturing apparatus according to any of first aspects A1 to fourth aspects A4, further comprising a particle separation system disposed within the closed loop to receive a gas stream from the process chamber and provide a gas stream to the blower, the particle separation system configured to remove particles from the gas stream.

[0009] A sixth aspect A6 comprises the additive manufacturing apparatus of the fifth aspect A5, wherein the particle separation system comprises a plurality of cyclone separators arranged in a plurality of arrays.

[0010] A seventh aspect A7 comprises the additive manufacturing apparatus of the sixth aspect A6, wherein the plurality of cyclone separators comprises twelve or more cyclone separators.

[0011] The eighth embodiment A8 uses 230 CFM of air or N 2 The additive manufacturing apparatus according to any one of fifth aspect A5 to seventh aspect A7, wherein the pressure drop across the particle separation system is less than about 1.5 psi when measured using a flow of gas.

[0012] A ninth aspect A9 includes a process chamber enclosing a print head, a recoat head, and a linear motion stage to which the print head and recoat head are coupled, the print head and recoat head operating in the process chamber to build a three dimensional object by depositing a build material and a binder material; the process chamber; a plurality of first sensors disposed in the process chamber, the plurality of first sensors comprising at least a temperature sensor and a pressure sensor; a particle separation system fluidly coupled to the process chamber to receive a particle-containing stream from the process chamber, the particle separation system separating at least some particles from the particle-containing stream to generate a particle-reduced stream; and a particle separation system fluidly coupled to the particle separation system to receive the particle-reduced stream from the particle separation system. an additive manufacturing apparatus comprising: a filter, the filter further removing particles from the particle reduced stream to provide a clean gas stream; a blower receiving the clean gas stream; a temperature control unit cooling the clean gas stream; a condenser system; and a plurality of second sensors positioned outside the process chamber after the particle separation system, the filter, the blower, the temperature control unit, and the condenser system and along a fluid recirculation path before the process chamber, the plurality of second sensors comprising at least a temperature sensor, a pressure sensor, and one or more of a VOC (volatile organic compound) sensor, a LEL (lower explosive limit) sensor, a humidity sensor, and a vapor sensor, wherein the process chamber, the particle separation system, the filter, the blower, the condenser system, and the temperature control unit form a closed loop.

[0013] A tenth aspect A10 comprises the additive manufacturing apparatus of the ninth aspect A9, wherein the filter is a HEPA (high efficiency particulate air) filter.

[0014] An eleventh aspect A11 comprises the additive manufacturing apparatus of the ninth aspect A9 or the tenth aspect A10, further comprising a first valve disposed between the particle separation system and the HEPA filter, and a second valve disposed along the fluid recirculation path between the blower and the HEPA filter, wherein closing the first valve and the second valve fluidly isolates the HEPA filter from the closed loop.

[0015] A twelfth aspect A12 comprises an additive manufacturing apparatus according to any of the ninth aspect A9 to the eleventh aspect A11, wherein the condenser system is positioned along the fluid recirculation path before the process chamber and after the pump.

[0016] A thirteenth aspect A13 comprises the additive manufacturing apparatus of any of the ninth aspect A9 to twelfth aspect A12, wherein the temperature control unit comprises a heat exchanger, and the condenser system passes the clean gas stream to the heat exchanger.

[0017] A fourteenth aspect A14 comprises the additive manufacturing apparatus of any of the ninth aspect A9 to the thirteenth aspect A13, further comprising a valve capable of bypassing the condenser system along the fluid recirculation path.

[0018] A fifteenth aspect A15 comprises the additive manufacturing apparatus of any of the ninth aspect A9 to the fourteenth aspect A14, wherein the clean gas stream comprises an inert gas.

[0019] A sixteenth aspect A16 comprises an additive manufacturing apparatus according to any of the ninth aspect A9 to the fifteenth aspect A15, wherein the environment within the process chamber is inert.

[0020] A seventeenth aspect A17 comprises an additive manufacturing apparatus according to any of the ninth aspects A9 to A16, wherein the process chamber comprises an inlet diffuser for admitting the clean gas stream into the process chamber, the inlet diffuser reducing a flow velocity of the clean gas stream.

[0021] An eighteenth aspect A18 includes a method of environmental control in a process chamber, comprising: receiving information regarding a temperature, pressure, and vapor content in the process chamber from at least one sensor disposed in the process chamber; removing a particle-containing stream from the process chamber; separating particles from the particle-containing stream to provide a clean gas stream; reducing a temperature, vapor content, or both of the clean gas stream based on the received information to achieve a predetermined temperature, pressure, and vapor content in the process chamber; and pumping the clean gas stream into the process chamber.

[0022] Aspect A19 includes the environmental control method of aspect A18, wherein separating the particles from the particle-containing stream includes directing the particle-containing stream through a particle separation system, a HEPA filter, or both.

[0023] A twentieth aspect A20 includes an environmental control method described in Aspects A18 or A19, receiving information regarding the pressure of the clean gas stream from a pressure sensor located outside the process chamber, and identifying an error in the particle separation system, the HEPA filter, or both based on a difference between the pressure of the clean gas stream and the pressure in the process chamber.

[0024] A twenty-first aspect A21 comprises the environmental control method according to any one of the eighteenth aspect A18 to the twenty-first aspect A21, wherein the clean gas stream is substantially free of oxygen. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic diagram of components of an additive manufacturing apparatus according to one or more embodiments shown and described herein. [Figure 2A]FIG. 2A generally depicts an embodiment of an actuator assembly for an additive manufacturing apparatus according to one or more embodiments shown and described herein. [Figure 2B] FIG. 2B is a schematic cross-sectional view of the actuator assembly of FIG. 2A. [Figure 2C] FIG. 2B is a schematic cross-sectional view of the actuator assembly of FIG. 2A. [Diagram 3] FIG. 3 illustrates a schematic of a portion of a control system for an additive manufacturing apparatus according to one or more embodiments shown and described herein. [Figure 4] FIG. 4 illustrates a schematic of an exemplary environmental system of an additive manufacturing apparatus according to one or more embodiments shown and described herein. [Diagram 5] FIG. 5 illustrates a schematic diagram of another exemplary environmental system of an additive manufacturing apparatus according to one or more embodiments shown and described herein. [Figure 6] FIG. 6 illustrates a schematic of an exemplary particle separation system for use in an additive manufacturing apparatus according to one or more embodiments shown and described herein. [Figure 7] FIG. 7 illustrates generally another exemplary particle separation system for use in an additive manufacturing apparatus according to one or more embodiments shown and described herein. [Figure 8] FIG. 8 generally depicts a cross-section of a cyclone separator for use in a particle separation system according to one or more embodiments shown and described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Additional features and advantages of the additive manufacturing apparatus, its components, and methods of use described herein will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description, or will be learned by practicing the embodiments described herein, including the following detailed description, the claims, and the accompanying drawings.

[0027] It should be understood that both the foregoing general description and the following detailed description are intended to describe various embodiments and provide an overview or framework for understanding the nature and features of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments described herein and, together with the description, serve to explain the principles and operation of the claimed subject matter.

[0028] Embodiments of an additive manufacturing apparatus and its components are described in detail below with reference to the accompanying drawings. Whenever possible, the same reference numbers are used throughout the drawings to refer to the same or similar parts. The additive manufacturing apparatus may include a closed-loop environmental system that monitors and manages the environment within a process chamber of the additive manufacturing apparatus. The closed-loop environmental system may allow the environment within the process chamber to be transformed between an inert and a non-inert state and maintained during the build of an object and between builds of different objects. In this manner, the additive manufacturing apparatus may use a chemically reactive build material to build the build material while maintaining a stable boundary when the atmosphere of the process chamber is inert. Various embodiments of an additive manufacturing apparatus and methods of use thereof are described in further detail herein with particular reference to the accompanying drawings.

[0029] Orientation terms used herein, e.g., up, down, right, left, front, back, top, bottom, upward, downward, refer only to the depicted figures and are not intended to imply absolute orientation unless expressly stated otherwise. Connection references (e.g., attached, coupled, connected, joined) should be interpreted broadly and can include intermediate members between collections of elements and relative movement between elements unless otherwise stated. Thus, connection references do not necessarily infer that two elements are directly connected and in fixed relationship to each other. The exemplary figures are for illustrative purposes only, and the dimensions, positions, order, and relative sizes reflected in the figures attached hereto may be altered.

[0030] The terms "coupled," "fixed," "attached," and the like, unless otherwise specified in this specification, refer to both direct coupling, fixing, or attachment, and indirect coupling, fixing, or attachment through one or more intermediate components or features.

[0031] The singular forms "a," "an," and the like include plural references unless the context clearly dictates otherwise.

[0032] Approximation language as used herein throughout the specification and claims is applied to modify any quantitative expression that may be permissibly varied without resulting in a change in the basic function to which it pertains. Thus, values ​​modified by terms such as "about," "approximately," and "substantially" should not be limited to the exact value specified. In at least some cases, the approximation language may correspond to the precision of an instrument for measuring a value, or the precision of a method or machine for building or manufacturing a component and / or system. For example, the approximation language may refer to being within a margin of 10 percent.

[0033] Throughout the specification and claims, range limitations are combinable and interchangeable, and such ranges include and are specific to all subranges contained therein, unless the context or language dictates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0034] 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.

[0035] Referring now to FIG. 1, an embodiment of an additive manufacturing apparatus 100 is shown in schematic form. The apparatus 100 includes a cleaning station 110, a build platform 120, and an actuator assembly 102. The apparatus 100 may optionally include a supply platform 130. The actuator assembly 102 includes, among other things, a recoat head 140 for dispensing the build material 400, and a print head 150 for depositing the binder material 500. In an embodiment, the recoat head 140 may further include an energy source for curing the binder material 500, as described in more detail herein. The actuator assembly 102 may be configured to facilitate independent control of the recoat head 140 and the print head 150 along an actuation axis 116 of the apparatus 100. This allows the recoat head 140 and the print head 150 to traverse the actuation axis 116 of the apparatus 100 in the same and / or opposite directions, and allows the recoat head 140 and the print head 150 to traverse the actuation axis 116 of the apparatus 100 at different and / or the same speeds. Independent actuation and control of the recoat head 140 and the print head 150 allows at least some steps of the additive manufacturing process to be performed simultaneously, thereby making the total cycle time of the additive manufacturing process shorter than the sum of the cycle times for each individual step. In the embodiment of the apparatus 100 described herein, the actuation axis 116 of the apparatus 100 is parallel to the + / -X axis of the coordinate system shown in the figures. It should be understood that the components of the additive manufacturing apparatus 100 that traverse the actuation axis 116, such as the recoat head 140, the print head 150, etc., do not have to be centered on the actuation axis 116. However, in the embodiment described herein, at least two of the components of the additive manufacturing apparatus 100 are positioned relative to the actuation axis 116 such that as the components traverse the actuation axis, they may occupy the same or overlapping volumes along the actuation axis if not properly controlled.

[0036] In the embodiment shown in FIG. 1 , the apparatus 100 includes a cleaning station 110, a build platform 120, a supply platform 130, and an actuator assembly 102. However, it should be understood that in other embodiments, the apparatus 100 does not include the supply platform 130, such as, for example and without limitation, an embodiment in which build material is supplied to the build platform 120 using a build material hopper. In the embodiment shown in FIG. 1 , the cleaning station 110, the build platform 120, and the supply platform 130 are disposed in series along the actuation axis 116 of the apparatus 100 between a print home position 158 of the print head 150 located proximate the −X end of the actuation axis 116 and a recoat home position 148 of the recoat head 140 located proximate the +X end of the actuation axis 116. That is, the print home position 158 and the recoat home position 148 are spaced apart laterally parallel to the + / −X coordinate system, and the cleaning station 110, the build platform 120, and the supply platform 130 are disposed therebetween. In the embodiment described herein, the build platform 120 is positioned along the actuation axis 116 of the apparatus 100 between the cleaning station 110 and the supply platform 130 .

[0037] The cleaning station 110 is located near one end of the actuation axis 116 of the apparatus 100 and is located at the same print home position 158 where the print head 150 is located and is "parked" before and after depositing binder material 500 onto the build material 400 located on the build platform 120. The cleaning station 110 may include one or more cleaning sections (not shown) to facilitate cleaning of the print head 150 between deposition operations. The cleaning sections may include, for example, but are not limited to, a dip station including a cleaning fluid for dissolving excess binder material on the print head 150, a wipe station for removing excess binder material and excess build material from the print head 150, a jet station for purging binder material and cleaning fluid from the print head 150, a park station for maintaining moisture in the nozzles of the print head 150, or various combinations thereof. The print head 150 may be transitioned between the cleaning sections by the actuator assembly 102.

[0038] The build platform 120 is coupled to a lift system 800 that includes a build platform actuator 122 to facilitate raising and lowering the build platform 120 in a vertical direction (i.e., parallel to the + / -Z direction of the coordinate axes shown in the figures) relative to the actuation axis 116 of the apparatus 100. The build platform actuator 122 can be, for example, but not limited to, a mechanical actuator, an electromechanical actuator, a pneumatic actuator, a hydraulic actuator, or any other actuator suitable for imparting linear motion to the build platform 120 in a vertical direction. Suitable actuators include, but are not limited to, worm drive actuators, ball screw actuators, pneumatic pistons, hydraulic pistons, electromechanical linear actuators, and the like. The build platform 120 and the build platform actuator 122 are disposed within a build receptacle 124 that is located below the actuation axis 116 of the apparatus 100 (i.e., in the -Z direction of the coordinate axes shown in the figures). During operation of the apparatus 100, the build platform 120 is retracted into the build receptacle 124 by operation of the build platform actuator 122 after each layer of binder material 500 is deposited onto the build material 400 located on the build platform 120.

[0039] The supply platform 130 is coupled to a lift system 800 that includes a supply platform actuator 132 to facilitate raising and lowering the supply platform 130 in a vertical direction (i.e., parallel to the + / -Z direction of the coordinate axes shown in the figures) relative to the actuation axis 116 of the device 100. The supply platform actuator 132 can be, for example, but not limited to, a mechanical actuator, an electromechanical actuator, a pneumatic actuator, a hydraulic actuator, or any other actuator suitable for imparting linear motion to the supply platform 130 in a vertical direction. Suitable actuators include, but are not limited to, worm drive actuators, ball screw actuators, pneumatic pistons, hydraulic pistons, electromechanical linear actuators, and the like. The supply platform 130 and the supply platform actuator 132 are disposed within a supply receptacle 134 that is located below the actuation axis 116 of the device 100 (i.e., in the -Z direction of the coordinate axes shown in the figures). During operation of the apparatus 100, the supply platform 130 is raised relative to the supply receptacle 134 toward the actuation axis 116 of the apparatus 100 by operation of the supply platform actuator 132 after a layer of build material 400 is dispensed from the supply platform 130 to the build platform 120, as described in further detail herein.

[0040] 1 and 2A, FIG. 2A illustrates a schematic of an actuator assembly 102 of the additive manufacturing apparatus 100 of FIG. 1. The actuator assembly 102 generally comprises a recoat head 140, a print head 150, a recoat head actuator 144, a print head actuator 154, and a support 182. In the embodiment described herein, the support 182 extends in a horizontal direction parallel to the actuation axis 116 (FIG. 1) of the apparatus 100 (i.e., parallel to the + / -X direction of the coordinate axes shown in the figures). As shown in FIG. 1, when the actuator assembly 102 is assembled on the cleaning station 110, the build platform 120, and the supply platform 130, the support 182 extends horizontally from at least the cleaning station 110 beyond the supply platform 130.

[0041] In one embodiment, the support 182 is a side of the rail 180 that extends in a horizontal direction. For example, in one embodiment, the vertical cross section of the rail 180 may be rectangular or square (i.e., a cross section in the YZ plane of the coordinate axes shown in the figure), with the rectangular or square side forming the support 182. However, it should be understood that other embodiments are contemplated and possible. For example, but not limited to, the rail 180 may have other cross-sectional shapes, such as an octagon, with the support 182 being a surface of one of the facets of the rail 180. In an embodiment, the support 182 is disposed in a vertical plane (e.g., a plane parallel to the XZ plane of the coordinate axes shown in the figure). However, it should be understood that in other embodiments, the support 182 is disposed in a plane other than a vertical plane.

[0042] In the embodiment described herein, the recoat head actuator 144 and the print head actuator 154 are coupled to the support 182 .

[0043] In the embodiments described herein, the recoat head actuator 144 is bidirectionally actuable along the recoat actuation axis 146, and the print head actuator 154 is bidirectionally actuable along the print actuation axis 156. That is, the recoat actuation axis 146 and the print actuation axis 156 define axes along which the recoat head actuator 144 and the print head actuator 154, respectively, are actuable. In embodiments, the recoat head actuator 144 and the print head actuator 154 are bidirectionally actuable independently of one another. The recoat actuation axis 146 and the print actuation axis 156 extend laterally and are parallel to the actuation axis 116 (FIG. 1) of the apparatus 100. In the embodiments described herein, the recoat actuation axis 146 and the print actuation axis 156 are collinear. This configuration allows the recoat head 140 and the print head 150 to occupy the same space (or portions of the same space) at different times along the actuation axis 116 of the apparatus 100, since the recoat actuation axis 146 and the print actuation axis 156 lie along the same line. In the embodiment of actuator assembly 102 shown in Figures 2A-2C, recoat actuating axis 146 and print actuating axis 156 lie in the same vertical plane. In embodiments in which support 182 is disposed in a vertical plane, recoat actuating axis 146 and print actuating axis 156 lie in a vertical plane parallel to the vertical plane of support 182, as shown in Figures 2A-2C. However, it should be understood that other embodiments are contemplated and contemplated, such as embodiments in which recoat actuating axis 146 and print actuating axis 156 lie in a vertical plane that is non-parallel to the plane of support 182.

[0044] In the embodiments described herein, the recoat head actuator 144 and the print head actuator 154 may be, for example, but not limited to, a mechanical actuator, an electromechanical actuator, a pneumatic actuator, a hydraulic actuator, or any other actuator suitable for providing linear motion. Suitable actuators include, but are not limited to, worm drive actuators, ball screw actuators, pneumatic pistons, hydraulic pistons, electromechanical linear actuators, etc. In one particular embodiment, the recoat head actuator 144 and the print head actuator 154 are linear actuators manufactured by Aerotech® Inc. of Pittsburgh, Pennsylvania, such as a PRO225LM mechanical bearing linear motor stage.

[0045] For example, the actuator assembly 102 may include a guide 184 mounted on a support 182 of a rail 180. The recoat head actuator 144 and the print head actuator 154 may be movably coupled to the rail 180 such that the recoat head actuator 144 and the print head actuator 154 can independently traverse the length of the guide 184. In an embodiment, motive force for traversing the recoat head actuator 144 and the print head actuator 154 is provided by a direct drive linear motor, such as, for example, a brushless servo motor.

[0046] In an embodiment, the recoat head actuator 144, the print head actuator 154, and the guide 184 may be a tightly fitted subsystem mounted on the rail 180, such as when the recoat head actuator 144 and the print head actuator 154 are similar to a PRO225LM mechanical bearing, linear motor stage, for example. However, it should be understood that other embodiments are contemplated and contemplated, such as embodiments in which the recoat head actuator 144 and the print head actuator 154 comprise multiple components that are individually assembled on the rail 180 to form the recoat head actuator 144 and the print head actuator 154, respectively.

[0047] 2A-2C, the recoat head 140 is coupled to a recoat head actuator 144 such that the recoat head 140 is located proximate to the actuation axis 116 (FIG. 1) of the additive manufacturing apparatus 100. Thus, bidirectional actuation of the recoat head actuator 144 along the recoat actuation axis 146 affects bidirectional movement of the recoat head 140 on the actuation axis 116 of the additive manufacturing apparatus 100. In the embodiment of the actuator assembly 102 shown in FIGS. 2A-2C, the recoat head 140 is coupled to the recoat head actuator 144 using struts 212 such that the recoat head 140 is cantilevered from the support 182 and positioned on the actuation axis 116 (FIG. 1) of the additive manufacturing apparatus 100. By cantilevering the recoat head 140 from the support 182, the recoat head actuator 144 and guide 184 can be spaced, for example, from the build platform 120 of the additive manufacturing apparatus 100, thereby reducing the likelihood that the recoat head actuator 144, guide 184, and associated electronics will become fouled or contaminated with the build material 400. This allows for longer periods between maintenance of the recoat head actuator, longer useful life of the recoat head actuator, less machine downtime, and reduced build errors due to contamination of the recoat head actuator 144. Additionally, by spaced the recoat head actuator 144 from the build platform 120 of the apparatus 100, visual and physical access to the build platform 120 and supply platform 130 can be improved, improving ease of maintenance and allowing for better visual observation (from human observation, camera systems, etc.) of the additive manufacturing process. In some embodiments described herein, the recoat head 140 may be fixed in a direction perpendicular to the recoat actuation axis 146 and the actuation axis 116 (i.e., fixed along a + / -Z axis and / or fixed along a + / -Y axis).

[0048] In an embodiment, the recoat head 140 may be pivotally coupled to the recoat head actuator 144. For example, and without limitation, in the embodiment of the actuator assembly 102 shown in FIGS. 2A-2C, a strut 212 is coupled to the recoat head 140 and is pivotally coupled to the recoat head actuator 144 at a pivot point 214. This allows the recoat head 140 to be pivoted away from the actuation axis 116 (FIG. 1) of the apparatus 100 relative to the recoat head actuator 144, for example, to facilitate maintenance or removal of an apparatus component located below the recoat head 140 (e.g., build receptacle, supply receptacle, etc.). In an embodiment, the pivot point 214 may include an actuator, such as a motor, to facilitate automatic pivoting of the recoat head 140. In an embodiment, a separate actuator (not shown) may be provided between the recoat head 140 and the recoat head actuator 144 to facilitate automatic pivoting of the recoat head 140. Although FIG. 2C shows the pivot point 214 located between the strut 212 and the recoat head actuator 144, it should be understood that other embodiments are contemplated and possible, for example, embodiments in which the pivot point 214 is located between the strut 212 and the recoat head 140.

[0049] 2A-2C, the print head 150 is coupled to a print head actuator 154 such that the print head 150 is located proximate to the actuation axis 116 (FIG. 2) of the additive manufacturing apparatus 100. Thus, bidirectional actuation of the print head actuator 154 along the print actuation axis 156 affects bidirectional movement of the print head 150 on the actuation axis 116 of the additive manufacturing apparatus 100. In the embodiment of the actuator assembly 102 shown in FIGS. 2A-2C, the print head 150 is coupled to the print head actuator 154 using struts 216 such that the print head 150 is cantilevered from the support 182 and positioned on the actuation axis 116 (FIG. 1) of the additive manufacturing apparatus 100. By cantilevering the print head 150 from the support 182, the print head actuator 154 and guide 184 can be spaced, for example, from the build platform 120 of the additive manufacturing apparatus 100, thereby reducing the likelihood that the print head actuator 154, guide 184, and associated electronics will become contaminated with build material 400 or otherwise contaminated. This can result in longer maintenance intervals for the print head actuator, longer useful life for the print head actuator, less machine downtime, and fewer build misses due to dirty print head actuator 154. Additionally, by spaced the print head actuator 154 from the build platform 120 of the apparatus 100, visual and physical access to the build platform 120 and supply platform 130 can be improved, improving ease of maintenance and allowing better visual observation (from human observation, camera systems, etc.) of the additive manufacturing process. In some embodiments described herein, the print head 150 may be fixed in a direction perpendicular to the recoat actuation axis 146 and the actuation axis 116 (i.e., fixed along a + / -Z axis and / or fixed along a + / -Y axis).

[0050] In an embodiment, the printhead 150 may be pivotally coupled to the printhead actuator 154. For example, and without limitation, in the embodiment of the actuator assembly 102 shown in FIGS. 2A-2C, a strut 216 is coupled to the printhead 150 and is pivotally coupled to the printhead actuator 154 at a pivot point 218. This allows the printhead 150 to be pivoted away from the actuation axis 116 (FIG. 1) of the apparatus 100 relative to the printhead actuator 154 to facilitate, for example, maintenance or removal of an apparatus component (e.g., build receptacle, supply receptacle, etc.) located below the printhead 150. In an embodiment, the pivot point 218 may include an actuator, such as a motor, to facilitate automated pivoting of the printhead 150. In an embodiment, a separate actuator (not shown) may be provided between the printhead 150 and the printhead actuator 154 to facilitate automated pivoting of the printhead 150. Although FIG. 2B shows the pivot point 218 located between the strut 216 and the printhead actuator 154, it should be understood that other embodiments are contemplated and contemplated, such as embodiments in which the pivot point 218 is located between the strut 216 and the printhead 150.

[0051] In an embodiment, the recoat head actuator 144 and the print head actuator 154 overlap over the build receptacle 124. Thus, the ranges of motion of the recoat head actuator 144 (and attached recoat head 140) and the print head actuator 154 (and attached print head 150) also overlap over the build receptacle 124. In an embodiment, the range of motion of the recoat head actuator (and attached recoat head 140) is greater than the range of motion of the print head actuator 154 (and attached print head 150). This is the case, for example, when the apparatus 100 includes a supply receptacle 134 disposed between the build receptacle 124 and the recoat home position 148. However, it should be understood that other embodiments are contemplated and possible. For example, in an embodiment (not shown), the recoat head actuator 144 and the print head actuator 154 can overlap along the entire length of the actuation axis 116 of the apparatus 100. In these embodiments, the range of motion of the recoat head actuator 144 (and attached recoat head 140 ) and the print head actuator 154 (and attached print head 150 ) are coextensive across the actuation axis 116 of the apparatus 100 .

[0052] As mentioned above, in the embodiments described herein, the recoat head 140 and the print head 150 are both positioned on the actuation axis 116 of the apparatus 100. Thus, the movement of the recoat head 140 and the print head 150 on the actuation axis 116 occurs along the same axis and is therefore collinear. In this configuration, the recoat head 140 and the print head 150 can occupy the same space (or a portion of the same space) along the actuation axis 116 of the apparatus 100 at various times during a single build cycle. The recoat head 140 and the print head 150 can move in concert along the actuation axis 116 of the apparatus 100 at the same time, in the same direction and / or in opposite directions, at the same speed or at different speeds. This, in turn, allows individual steps of an additive manufacturing process, such as a dispensing step (also referred to herein as a recoating step), a deposition step (also referred to herein as a printing step), a curing (or heating) step, and / or a cleaning step, to occur with overlapping cycle times. For example, a dispense step may be initiated while a cleaning step is completing, a deposition step may be initiated while a dispense step is completing, and / or a cleaning step may be initiated while a dispense step is completing, which can make the total cycle time of the additive manufacturing apparatus 100 shorter than the sum of the dispense cycle time (also referred to herein as a recoat cycle time), the deposition cycle time (also referred to herein as a print cycle time), and / or the cleaning cycle time.

[0053] Other embodiments of an actuator assembly (not shown) may be implemented in the embodiment of additive manufacturing apparatus 100 shown in FIG 1, for example, as a replacement for actuator assembly 102. It should thus be understood that other embodiments of actuator assemblies may be utilized to build objects on build platform 120 in a manner similar to that described herein with respect to FIGS. 1-2C.

[0054] 1-2C, in the embodiments described herein, the print head 150 can deposit binder material 500 onto a layer of build material 400 dispensed onto the build platform 120 through a nozzle array 172 disposed on the underside of the print head 150 (i.e., the side of the print head 150 that faces the build platform 120). In an embodiment, the array of nozzles 172 is spatially distributed in the XY plane of the coordinate axes shown in the figures. In some embodiments, the print head can also define the geometry of the part to be built. In an embodiment, the nozzle 172 can be a piezoelectric print nozzle, in which case the print head 150 is a piezoelectric print head. In an alternative embodiment, the nozzle 172 can be a thermal print nozzle, in which case the print head 150 is a thermal print head. In an alternative embodiment, the nozzle 172 can be a spray nozzle.

[0055] In addition to the nozzles 172, in some embodiments, the print head 150 can further include one or more sensors (not shown) for detecting properties of the build material 400 dispensed onto the build platform 120 and / or the binder material 500 deposited on the build platform 120. Examples of sensors include, but are not limited to, imaging sensors such as cameras, thermal detectors, pyrometers, profilometers, ultrasonic detectors, etc. In these embodiments, signals from the sensors can be fed back to a control system (described in more detail herein) of the additive manufacturing device to facilitate feedback control of one or more functions of the additive manufacturing device.

[0056] Alternatively or additionally, the print head 150 can include at least one energy source (not shown). The energy source can emit a wavelength or range of wavelengths of electromagnetic radiation suitable for curing (or at least initiating curing) the binder material 500 deposited on the build material 400 dispensed on the build platform 120. For example, the energy source can include an infrared heater or an ultraviolet lamp that emits wavelengths of infrared or ultraviolet radiation suitable for curing the binder material 500 previously deposited on the build material 400 dispensed on the build platform 120. If the energy source is an infrared heater, the energy source can also pre-heat the build material 400 as it is dispensed from the supply platform 130 to the build platform 120, which can help facilitate curing of the subsequently deposited binder material 500.

[0057] As described herein, the recoat head 140 is used in the additive manufacturing apparatus 100 to dispense the build material 400, and more specifically, to dispense the build material 400 from the supply platform 130 to the build platform 120. That is, the recoat head 140 is used to "recoat" the build platform 120 with the build material 400. It is contemplated that the recoat head 140 may include at least one of a roller, a blade, or a wiper to facilitate dispensing the build material 400 from the supply platform 130 to the build platform 120.

[0058] The build material generally comprises a powder material that is spreadable or flowable. Suitable categories of powder materials include, but are not limited to, dry powder materials and wet powder materials (e.g., powder materials mixed in a slurry). In some embodiments, the build materials can be bound together with a binder material. In some embodiments, the build materials can also be fused together, such as by sintering. In embodiments, the build material can be an inorganic powder material, including, but not limited to, ceramic powder, metal powder, glass powder, carbon powder, sand, cement, calcium phosphate powder, and various combinations thereof. In embodiments, the build material can include an organic powder material, including, but not limited to, plastic powder, polymer powder, soap, powder formed from food (i.e., edible powder), and various combinations thereof. In embodiments, the build material can be stainless steel (e.g., SS316, 17-4, HK-30, and 304 powders), steel (e.g., 4140, 4605, 8620, and tool steel powders), copper alloys, nickel alloys (e.g., Rene 65), or other alloy powders. In some embodiments, the build material may be a pharma- ceutical active ingredient (or may include a pharma-ceutical active ingredient), such as when the build material is or contains a pharmaceutical. In embodiments, the build material may be a combination of inorganic and organic powder materials. In some embodiments, the build material may be a chemically reactive or combustible powder, such as aluminum or titanium powder.

[0059] The build material may be uniform in size or non-uniform in size. In embodiments, the build material may have a powder size distribution, such as, for example, but not limited to, a bimodal or trimodal powder size distribution. In embodiments, the build material may be or include nanoparticles.

[0060] The build materials may be of regular or irregular shape and may have different or the same aspect ratios, for example, the build materials may be in the form of globules or granules, or may be shaped like rodlets or fibers.

[0061] In embodiments, the build material can be coated with a second material. For example, but not limited to, the build material can be coated with a wax, a polymer, or another material that helps hold the build material together (as with a binder). Alternatively or additionally, the build material can be coated with a sintering agent and / or an alloying agent to facilitate fusing of the build material.

[0062] The binder material can include a substance that is radiant energy curable and can adhere or bond build materials when the binder material is in a cured state. As used herein, the term "radiant energy curable" refers to any material that solidifies in response to the application of radiant energy of a particular wavelength and energy. For example, the binder material can include known photopolymerizable resins that include a photoinitiator compound to change the resin from a liquid state to a solid state. Alternatively, the binder material can include a substance that includes a solvent that can be evaporated by the application of radiant energy. The uncured binder material can be provided in a solid (e.g., granular) form, a liquid form including a paste or slurry, or a low viscosity liquid compatible with a print head. The binder build can be selected to be able to degas or burn off during further processing, such as during sintering of the build material. In some embodiments, the binder material is described in U.S. Patent Application Publication No. 2018 / 0071820, "Reversible Binders for Use in Binder Jet Additive Manufacturing Techniques," assigned to General Electric Company, Schenectady, New York. However, it should be understood that other binder materials are contemplated and contemplated, including combinations of various binder materials.

[0063] In embodiments, the recoat head 140 can further comprise at least one energy source. In these embodiments, the energy source can emit electromagnetic waves at a wavelength or range of wavelengths suitable for curing (or at least initiating curing) the binder material 500 deposited on the build material 400 dispensed on the build platform 120. For example, the energy source can include an infrared heater or an ultraviolet lamp that emits infrared or ultraviolet light, respectively, suitable for curing the binder material 500 previously deposited on the build material 400 dispensed on the build platform 120. If the energy source is an infrared heater, the energy source can also preheat the build material 400 as it is dispensed from the supply platform 130 to the build platform 120, which can help promote curing of the subsequently deposited binder material 500.

[0064] In some embodiments, the recoat head 140 may further comprise at least one sensor, such as at least one sensor for detecting a property of the build material 400 distributed on the build platform 120 and / or the binder material 500 deposited on the build platform 120. Examples of sensors include, but are not limited to, imaging sensors, such as cameras, thermal detectors, pyrometers, profilometers, ultrasonic detectors, etc. In these embodiments, signals from the sensors may be fed back to a control system (described in more detail herein) of the additive manufacturing device to facilitate feedback control of one or more functions of the additive manufacturing device.

[0065] Referring now to FIGS. 1 and 3, FIG. 3 illustrates a schematic of a portion of a control system 200 for controlling the additive manufacturing apparatus 100 of FIG. 1 using an actuator assembly as shown in FIGS. 2A-2C. The control system 200 is communicatively coupled to the recoat head actuator 144, the print head actuator 154, the build platform actuator 122, and the supply platform actuator 132. The control system 200 may also be communicatively coupled to the print head 150 and the recoat head 140. In embodiments in which additional accessories or components are included, such as process accessories, process accessory actuators, and sensors (not shown), the control system 200 may also be communicatively coupled to the additional components. In the embodiments described herein, the control system 200 comprises a processor 202 communicatively coupled to a memory 204. The processor 202 may include any processing component, such as a central processing unit, configured to receive and execute computer-readable and executable instructions stored in the memory 204, for example. In the embodiments described herein, a processor 202 of the control system 200 is configured to provide control signals to the recoat head actuator 144, the print head actuator 154, the build platform actuator 122, the supply platform actuator 132, and any additional components (if included). The processor 202 may also be configured to provide control signals to (and thereby actuate) the print head 150 and the recoat head 140. The control system 200 may also be configured to receive signals from one or more sensors in the recoat head 140 and actuate one or more of the recoat head actuator 144, the print head actuator 154, the build platform actuator 122, the supply platform actuator 132, the print head 150, and / or the recoat head 140 based on these signals.

[0066] In the embodiments described herein, computer readable and executable instructions for controlling the additive manufacturing apparatus 100 are stored in memory 204 of the control system 200. The memory 204 is a non-transitory computer readable memory. The memory 204 may be configured as, for example, but not limited to, volatile and / or non-volatile memory and thus may include random access memory (including SRAM, DRAM, and / or other types of random access memory), flash memory, registers, compact discs (CDs), digital versatile discs (DVDs), and / or other types of storage components.

[0067] 1 , an additive manufacturing apparatus 100 is shown generally at the start of a build cycle. As used herein, the term “build cycle” refers to the process of building a single layer of an object on a build platform 120. In the embodiments described herein, a “build cycle” can include one iteration of each of raising the supply platform 130, lowering the build platform 120, dispensing a new layer of build material 400 from the supply platform 130 to the build platform 120, depositing a binder material 500 on the new layer of build material 400 dispensed on the build platform 120, and optionally cleaning the print head 150.

[0068] 1 illustrates an additive manufacturing apparatus 100 with a supply receptacle 134 that is used with a recoat head 140 of an actuator assembly 102 to supply build material 400 to a build platform 120 of a build receptacle 124, it is to be understood that other embodiments are contemplated and contemplated. For example, in an embodiment, the apparatus 100 can include a build material hopper instead of a supply receptacle. In such an embodiment, the build material hopper can be coupled to the recoat head actuator 144 or fixed above the build platform 120. Additionally, while FIG. 1 illustrates an additive manufacturing apparatus 100 with an actuator assembly as shown in FIGS. 2A-2C, it is to be understood that other configurations of actuator assemblies are contemplated and contemplated.

[0069] Additionally, while various embodiments described herein are described with respect to print heads that deposit binder material onto a powder bed, it should be understood that other additive manufacturing modalities are contemplated and contemplated, for example, the print heads described herein can be replaced with lasers or other energy beams or other consolidation devices.

[0070] The foregoing description includes various embodiments of the components of an additive manufacturing apparatus and methods for using the same. It should be understood that various combinations of these components, including the print head 150, the recoat head 140, and the linear motion stage coupled to the print head actuator 154 and the recoat head actuator 144, are provided within a process chamber controlled by a closed-loop environmental system. The environmental system allows the process chamber to be altered between an inert state (e.g., a chemically reactive powder can be used as a build material) and a non-inert state. Thus, various embodiments of the additive manufacturing system allow a wider range of build materials to be used and also allow additional control of the environment within the process chamber, which can increase precision between build materials.

[0071] In various embodiments, certain components are described as being "upstream" or "downstream" of one another. As used herein, the term "upstream" refers to moving in a direction toward the outlet to the process chamber, or a component that is relatively closer to the outlet of the process chamber compared to another component along the flow path in the direction of fluid flow. The term "downstream" used in conjunction with "upstream" refers to a direction toward the inlet of the process chamber, or a direction that is relatively closer to the inlet of the process chamber compared to another component. In general, fluid flow through an environmental system is from upstream to downstream. As used herein, the term "direct" when used in conjunction with "upstream" or "downstream" refers to an arrangement in which the gas flow flows from a first component to a second component without passing through an intervening component. However, it is contemplated that the gas flow may be passed by one or more sensors or through one or more valves without affecting the direct relationship between the components.

[0072] 4 and 5, an embodiment of an environmental system 401, 501 of an additive manufacturing device is shown generally. Generally, the environmental system 401, 501 includes a process chamber 300 that encloses a print head 150, a recoat head 140, and a linear motion stage 420. The linear motion stage 420 is coupled to a print head actuator 154 and a recoat head actuator 144, as described above. The print head 150 and the recoat head 140 operate within the process chamber 300 to build a three-dimensional object by depositing a build material 400 and a binder material 500, as described above. Within the environmental system 401, 501, there are a number of valves, generally and collectively referred to as valves 40, or individually referred to by the reference number 40 followed by an alphabetical indicator (e.g., 40a, 40b, etc.), operable to control gas flow between various components that make up the closed loop of the environmental system 401, 501. Additionally, a number of sensors, collectively referred to as sensors 44 or individually referenced by reference number 44 followed by an alphabetical indicator (e.g., 44a, 44b, etc.), are located at various points throughout the closed loop of the environmental system. In an embodiment, one or more of the valves 40 may be operated based on information provided by one or more of the sensors 44 to a control system (such as control system 200 of FIG. 2).

[0073] In the following description, sensors 44 located throughout the closed loop environmental system may include one or more sensors at each location indicated as a sensor 44. Suitable sensors may include, by way of example and not limitation, pressure sensors, temperature sensors, humidity sensors, vapor sensors, volatile organic compound (VOC) sensors, lower explosive limit (LEL) sensors, oxygen sensors, and the like.

[0074] 4 and 5, particle separation system 402 is fluidly coupled to process chamber 300 to receive a particle-containing stream from process chamber 300. For example, in an embodiment, when valves 40a and 40b are opened, a gas stream containing particles of build material 400 and water vapor and / or solvent vapor produced by volatilization of binder material 500 and cleaning fluid is extracted from process chamber 300.

[0075] 4 and 5, the valve 40a is disposed between the recoat head 140 and the particle separation system 402. The valve 40a can be used to control the gas flow received by the recoat head 140, such as through a vacuum system coupled to the recoat head 140. In an embodiment, the vacuum draws a gas flow through the recoat head 140 at a flow rate of greater than about 20 cubic feet per minute (CFM). Thus, the vacuum system can include a tube coupled to an inlet of the recoat head 140 that draws a gas flow through the recoat head 140 and removes the build material that is aerosolized by disturbing the build material as the recoat head 140 passes over the build surface or any other surface covered with powder. The vacuum system can vary depending on the particular embodiment, provided that it is effective to remove the build material that is aerosolized or fluidized within the process chamber 300. One example of a vacuum system suitable for use is described in further detail in patent application PCT / US20 / 34204, filed May 22, 2020, entitled "Additive Manufacturing Recoat Assembly Including a Vacuum and Methods of Use Thereof," the contents of which are incorporated herein by reference. It is contemplated that in some embodiments the recoat head 140 may not include such a vacuum system, and thus in such embodiments the valve 40a may not be included. In an embodiment, the valve 40a is a throttle valve that allows the gas flow from the recoat head 140 to be turned on, off, or adjusted, although other types of valves could be used.

[0076] Another valve, valve 40b, is disposed between the process chamber 300 and the particle separation system 402 to control gas flow from the process chamber 300. In an embodiment, valve 40b is a throttling valve that allows gas flow from the process chamber 300 to be turned on, off, or adjusted, although it is contemplated that other types of valves may be used.

[0077] 4 and 5, if included, the flow through valve 40a merges with the flow through valve 40b upstream of particle separation system 402. In an embodiment, a venturi (not shown) is included in the flow path where the flow through valve 40a merges with the flow through valve 40b. If included, the venturi creates a low pressure area at the throat of the venturi, which is effective to drive the intake flow from recoat head 140. In an embodiment, the venturi has a geometry selected to meet the minimum flow rate of the environmental system, which may vary based on, for example, the volume of recoat head 140 and the intake flow of gas drawn through recoat head 140.

[0078] At least one sensor 44a is positioned immediately upstream of the particle separation system 402. Although a single sensor 44a is shown, it is contemplated that any number of sensors 44a may be positioned along the flow path upstream of the particle separation system 402. For example, in some embodiments, the sensor 44a may include a temperature sensor, a pressure sensor, or both. The temperature sensor measures the temperature of the particle-containing stream, while the pressure sensor measures the pressure of the particle-containing stream. If included, information received from the pressure sensor may be used to determine whether a leak exists within the closed loop of the environmental system.

[0079] The particle separation system 402 separates and removes at least a portion of the particles and sends the particles to the material handling system 403. In an embodiment, the valve 40c controls the flow of particles from the environmental system to the material handling system 403. As described in more detail below, the valve 40c is, in an embodiment, an on / off valve that allows particles to pass from the particle separation system 402 to the material handling system 403 when in an on position and prevents particles from passing from the particle separation system 402 to the material handling system 403 when in an off position. However, other types of valves may be used. The separation of at least a portion of the particles from the particle-containing stream by the particle separation system 402 results in a particle-reduced stream that is passed through a filter 404 fluidly coupled to the particle separation system 402. Although in an embodiment, the particle separation system 402 is the particle separation system shown and described in any one of Figures 6-8, it is contemplated that other particle separation systems may be used depending on the particular embodiment.

[0080] In various embodiments, the particle separation system 402 is effective to remove greater than about 50%, 75%, 80%, 85%, 90%, 95%, or even 97% by weight of the particles in the particle-containing stream. In embodiments, the particle separation system 402 separates particles from the particle-containing stream that are greater than about 5.0 microns (μm), greater than about 4.0 μm, greater than about 3.5 μm, greater than about 3.0 μm, greater than about 2.5 μm, greater than about 2.0 μm, greater than about 1.5 μm, or even greater than about 1.0 μm. Thus, in embodiments, the particle separation system 402 reduces the load on the filter 404 by removing a majority of the particles from the particle-containing stream.

[0081] As shown in FIGS. 4 and 5, in an embodiment, a sensor 44b is disposed along the flow path between the particle separation system 402 and the filter 404. Although a single sensor 44b is shown, it is contemplated that any number of sensors 44 may be disposed along the flow path between the particle separation system 402 and the filter 404. For example, in some embodiments, the sensor 44b may include a temperature sensor, a pressure sensor, or both. In one particular embodiment, a pressure sensor and a temperature sensor are disposed between the particle separation system 402 and the filter 404. In another embodiment, a pressure sensor is between the particle separation system 402 and the filter 404. If the sensor 44b includes a pressure sensor, it may be used to determine whether a leak exists in the closed loop of the environmental system. Additionally or alternatively, information from the sensor 44b may be used in conjunction with the sensor 44a (when the sensor 44a includes a pressure sensor) to determine whether a problem exists in the particle separation system 402. Such a problem may be indicated, for example, by a pressure drop (eg, a pressure difference between the pressure sensed by sensor 44a and the pressure sensed by sensor 44b) that is greater than expected (eg, a threshold pressure difference).

[0082] In an embodiment, the filter 404 is a high efficiency particulate air (HEPA) filter (as defined by the U.S. Department of Energy). For example, in an embodiment, the filter 404 is a HEPA filter capable of removing at least 99.97% of particles having a diameter of 0.3 μm. Other types of filters can be used, provided they are capable of removing residual particles from the reduced particle stream. For example, if a build material having a larger particle size is used, other types of filters may be used. Additionally or alternatively, different types of filters can be used depending on other system components and requirements, such as available pressure drop and flow rate. In an embodiment, the build material 400 has a d10 of 3.5 μm or greater, and a HEPA filter is used as the filter 404. In various embodiments, the filter 404 removes remaining particles of the build material 400 from the reduced particle stream and provides a clean gas stream.

[0083] As shown in Figures 4 and 5, in an embodiment, valves 40d and 40e are provided immediately upstream and downstream of filter 404, respectively, to allow filter 404 to be fluidly isolated. Thus, in such an embodiment, filter 404 can be removed, cleaned, or replaced without allowing gas within environmental system 401, 501 to escape the closed loop. In an embodiment, valves 40d and 40e are manual on / off valves that can be operated between an on position, in which gas can flow through filter 404, and an off position, in which gas is prevented from flowing through filter 404 by an operator. However, other types of valves, including automatic valves, are contemplated and possible.

[0084] As shown in Figures 4 and 5, the filter 404 is fluidly coupled to the blower 406. Although Figures 4 and 5 are shown as including only a single blower 406, it is contemplated that one or more additional blowers may be included in embodiments. For example, the particle separation system 402 may include a blower. In Figure 4, the filter 404 passes the clean gas stream directly to the blower 406, while in Figure 5, at least a portion of the clean gas stream passes through a dehumidifier 502 (described in more detail below) before being provided to the blower 406. The blower 406 circulates the clean gas stream through the environmental system. The blower 406 may include any one of several commercially available blowers, including, but not limited to, those available as HRD 2T FU ATEX™, such as the HRD 2T FU-95 / 2.2 with variable frequency drive (VFD) available from Electro-Air Systems, Germany, or a 3TA series centrifugal blower available from Airtech Vacuum in conjunction with a VFD. Other blowers may be used, provided they can provide the pressure and flow rate required by the system. For example, in embodiments, the blower 406 provides a driving pressure of 70 mbar or more, 75 mbar or more, 80 mbar or more, or even 85 mbar or more for the gas flowing through the environmental system. The blower 406 may also be selected based on, for example, blower characteristic speed, adiabatic efficiency, power output, and maximum flow rate. It should be understood that the selection of the blower 406 can and will affect the selection of other components in the system, including, but not limited to, the particle separation system 402 and the filter 404. In particular, the allowable pressure drop across the various components in the system, including the venturi, the particle separation system 402, and the filter 404, depends on the pressure tolerance of the blower 406.

[0085] Although described herein as being located upstream of the blower 406, it is contemplated that in embodiments the dehumidifier 502 may be located downstream of the blower 406. It should be appreciated that the order of components may vary depending on the particular components selected, as well as other system operating parameters. For example, the use of a blower that is inert to vapors from the binder and cleaning fluid may allow gases to pass through the blower without the need to extract vapors therefrom. Additionally, embodiments in which the vapor content and particular gases used within the process chamber do not pose a combustion risk, and / or the blower does not operate in a condensing environment, may allow gases to pass through the blower without the need to extract vapors therefrom. Thus, it should be appreciated that gases may be conditioned or treated upstream or downstream of the blower depending on the environment, operating parameters, gas content, and the particular blower selected.

[0086] In embodiments, such as the embodiment shown in FIG. 4, the sensor 44c is disposed along the flow path between the filter 404 and the blower 406. For example, the sensor 44c is disposed downstream of the filter 404 and the valve 40e, and upstream of the blower 406. Although a single sensor 44c is shown, it is contemplated that any number of sensors 44 may be disposed along the flow path between the filter 404 and the blower 406. For example, in some embodiments, the sensor 44c may include a temperature sensor, a pressure sensor, or both. In one particular embodiment, a pressure sensor and a temperature sensor are disposed between the filter 404 and the blower 406.

[0087] In an embodiment, sensors 44b and 44c each include a pressure sensor. Thus, together sensors 44b and 44c can provide information regarding the capacity of filter 404 and can indicate when filter 404 needs replacing.

[0088] In the embodiment shown in FIG. 4, the clean gas stream from the blower 406 may optionally be sent to a concentrator 408. The concentrator 408, if included, may concentrate vapors (e.g., vapors released from the cleaning fluid and / or binder material 500) in the clean gas stream to reduce the amount of gas stream passing through the condenser system 410. For example, the concentrator 408 may concentrate vapors present in the clean gas stream to a volume of less than about 50% (v / v), which is sent to the condenser system 410, while the remaining volume of the clean gas stream is looped back into the loop at a point downstream of the condenser system 410. Thus, if included, the concentrator 408 may improve the overall efficiency of the system. If the concentrator 408 is included and used, valves 40f and 40g may be closed to force the clean gas stream through the concentrator 408, and valve 40s may be opened to allow fluid communication with the concentrator 408.

[0089] As shown in FIG. 4, sensor 44d is disposed downstream of blower 406. Although shown as a single sensor 44d in the embodiment, sensor 44d can include a pressure sensor, a temperature sensor, and / or a humidity sensor. In some embodiments, a VOC or LEL sensor can be used instead of a humidity sensor. Thus, in the embodiment, the pressure sensor, the temperature sensor, and the VOC sensor are disposed immediately downstream of blower 406. In the embodiment, the pressure sensor, the temperature sensor, and the LEL sensor are disposed immediately downstream of blower 406. In the embodiment, the pressure sensor, the temperature sensor, and the humidity sensor are disposed immediately downstream of blower 406. Information from sensor 44d can be used, for example, to determine whether to close valve 40f, valve 40g, or both valves 40f and 40g, and whether to open valve 40s to reroute the clean gas stream exiting blower 406. For example, information from one or more of a humidity sensor, a VOC sensor, an LEL sensor, and a temperature sensor can be used to determine that the clean gas stream has a vapor concentration at temperatures T1 and V1, and that the clean gas stream (e.g., V threshold is the threshold level of steam, V1>V threshold ) that there is an undesirable level of vapor in concentrator 408. Thus, valves 40f, 40g, and / or 40s may be adjusted (e.g., valves 40f and 40g are closed and valve 40s is opened) to cause the clean gas stream to flow through concentrator 408. Alternatively, information from one or more of the humidity sensor, the VOC sensor, the LEL sensor, and the temperature sensor may be used to determine that the clean gas stream has a vapor concentration at temperatures T1 and V1, and that the concentration of vapors present in the clean gas stream is acceptable (e.g., V1≦V threshold) can be determined. Thus, valves 40f, 40g, and / or 40s can be adjusted (e.g., valves 40f and / or 40g are opened and valve 40s is closed) to cause the clean gas stream to bypass concentrator 408. Additionally or alternatively, when concentrator 408 and valve 40s are not present, information from one or more of the humidity sensor, VOC sensor, LEL sensor, and temperature sensor can be used to determine that the clean gas stream has a vapor concentration at temperature T1 and V1, that the concentration of vapors present in the clean gas stream is acceptable (e.g., V1≦V threshold ), and valves 40f and / or 40g can be adjusted (e.g., valve 40f is closed and valve 40g is opened) to cause the clean gas stream to bypass the condenser system 410. Additionally or alternatively, when concentrator 408 and valve 40s are not present, information from one or more of the humidity sensor, the VOC sensor, the LEL sensor, and the temperature sensor can be used to determine that the clean gas stream has a vapor concentration at temperature T1 and V1, and that the clean gas stream (e.g., V1>V threshold ), it may be determined that an undesirable level of steam is present in the condenser system 410, and valves 40f and / or 40g may be adjusted (e.g., valve 40f may be opened and valve 40g may be closed) to allow the clean gas stream to flow to the condenser system 410.

[0090] In an embodiment, one or both of valves 40f and 40g are throttling valves that can be used to turn on the flow of the clean gas stream, turn off the flow of the clean gas stream, or adjust the flow of the clean gas stream. Thus, while the above description of the operation of valves 40f and 40g simply refers to opening and closing the valves, it should be understood that the flow of the clean gas stream through the concentrator and / or condenser system may be further controlled through the use of throttling valves. However, other types of valves are possible and contemplated.

[0091] In embodiments where a concentrator 408 is not included or when a concentrator 408 is included and bypassed, the clean gas stream is passed from the blower 406 to a condenser system 410. The condenser system 410 includes a condensing unit and an evaporator coil in various embodiments and is operable to extract vapors from the clean gas stream, including, by way of example and not limitation, water and other solvent vapors emitted to the environment by the cleaning fluid in the cleaning station 110 (FIG. 1) and vapors from binder materials deposited and cured in the process chamber. The condenser system 410 may be, by way of example and limitation, an air conditioner conventionally used in commercial HVAC systems, such as those manufactured by and commercially available from Trane Technologies. In an embodiment, the condenser system 410 may be a 2.5 ton or larger commercial HVAC system, such as a PUY-A30NHA7 condensing unit from Mitsubishi Electric Trane HVAC US LLC (Suwanee, GA) and a DXG07C15 evaporator coil from Coilmaster Corporation (Moscow, TN).

[0092] The condenser system 410 removes vapors from the clean gas stream and, in embodiments, provides fluid (e.g., condensed vapors) to a cleaning fluid reservoir 412 where the fluid may be recirculated through a cleaning fluid recirculation loop (not shown). In other embodiments, the condensed vapors may be removed from the system or sent to a waste reservoir (not shown). In embodiments, the condensed vapors may be separated, cleaned, and / or treated for recirculation and / or delivery to a waste reservoir. Other methods of treating the condensed vapors are also contemplated. The clean gas stream with the vapors removed is then sent from the condenser system 410 to an optional heating coil 414.

[0093] In an embodiment, sensor 44e is disposed in a path immediately downstream of condenser system 410. Although shown as a single sensor 44e in the embodiment, sensor 44e can include a pressure sensor and / or a temperature sensor. Information from sensor 44e can include information regarding the pressure of the clean gas stream from condenser system 410, and / or information regarding the temperature of the clean gas stream from condenser system 410, which can be used, for example, to identify leaks within a closed loop of an environmental system, to identify functional problems with condenser system 410, and the like. In embodiments where a temperature sensor is included as sensor 44e, it can be used to adjust one or more parameters of heating coil 414 when information from the sensor is included. In an embodiment, if the clean gas stream received from condenser system 410 has T2 < T1 and V2 < V1, it has a vapor concentration of V2 and a temperature of T2. Thus, the condenser system receives a gas stream having a first vapor content V1 from the process chamber and provides the process chamber with a second vapor content V2 in the gas stream.

[0094] When included, heating coil 414 may be used to raise the temperature of the clean gas stream. For example, if the clean gas stream from condenser system 410 has a lower (e.g., lower than a threshold temperature) temperature than expected, heating coil 414 can be adjusted to raise the clean gas stream to a desired temperature. An example of a suitable heating coil 414 is a finned strip heater commercially available from Tempco Electric Heater Corporation (Wood Dale, IL) as model number CSF00131. From heating coil 414, when included, the clean gas stream flows into plenum 416. Thus, in an embodiment, if the clean gas stream exiting heating coil 414 has T3 > T2 and V3 ≈ V2, it has a vapor concentration of V3 and a temperature of T3.

[0095] 4 includes a blower 406, an optional concentrator 408, a condenser system 410, and an optional heating coil 414, it is contemplated that other components may be used to process and condition the clean gas stream exiting the filter 404. For example, in the embodiment shown in FIG. 5, an environmental system 501 includes a dehumidifier 502, a blower 406, and a heat exchanger 504.

[0096] In FIG. 5, valve 40e is disposed immediately downstream of filter 404. Sensor 44i is disposed downstream of valve 40e. Although shown as a single sensor 44i in an embodiment, sensor 44i can include a pressure sensor, a humidity sensor, a VOC sensor, and / or an LEL sensor. In an embodiment, sensor 44i includes a pressure sensor and a humidity sensor. In an embodiment, sensor 44i includes a pressure sensor and a VOC sensor. In an embodiment, sensor 44i includes a pressure sensor and an LEL sensor. Information from sensor 44i can include information regarding the pressure of the clean gas stream from filter 404 and / or the vapor content of the clean gas stream, which can be used to determine, for example, that the clean gas stream has a temperature T1 and a vapor content V1, and whether the clean gas stream should be diverted to dehumidifier 502 or sent directly to blower 406. In an embodiment, valves 40f and 40q can be operated to direct the clean gas stream based on information from sensor 44i.

[0097] For example, in an embodiment, in response to information from sensor 44i indicating that the vapor content of the clean gas stream is greater than desired (e.g., V threshold If V1>V threshold ), valve 40f can be closed and valve 40q can be opened to allow the clean gas stream to flow to the dehumidifier 502. Alternatively, in an embodiment, the vapor content of the clean gas stream can be adjusted to within a desired range (e.g., V≦V threshold), valve 40f can be opened and valve 40q can be closed to cause the clean gas stream to bypass dehumidifier 502 and flow to blower 406. In an embodiment, valves 40f and 40q are on / off valves that allow or prevent the clean gas stream from passing along the flow path, although other types of valves are possible and contemplated.

[0098] The dehumidifier 502 is operable to remove steam or moisture from the clean gas stream in embodiments. In some embodiments, the dehumidifier is a desiccant-based dehumidifier, such as a TTR-400D™ desiccant dehumidifier commercially available from Trotec, GmbH (Heinsberg, Germany). Other types of dehumidifiers, including refrigeration-based dehumidifiers, may be used in embodiments, provided they are capable of maintaining the humidity of the closed loop system within acceptable ranges in accordance with embodiments. However, in embodiments where a relatively large amount of moisture is to be removed from the clean gas stream (e.g., greater than about 1 kg / hr), a desiccant-based dehumidifier may provide improved moisture removal. In embodiments, the clean gas stream exiting the dehumidifier 502 has a steam content V2, and V2 <V1である。

[0099] After the clean gas stream passes through (or bypasses) the dehumidifier 502, the clean gas stream flows to the blower 406. In an embodiment, the sensor 44j is located just upstream of the blower 406. Although shown as a single sensor 44j in an embodiment, the sensor 44j may include a pressure sensor, a temperature sensor, and / or an oxygen sensor. In an embodiment, the sensor 44j includes a pressure sensor, a temperature sensor, and a pair of oxygen sensors.

[0100] 5, following the blower 406, the clean gas stream flows past sensor 44e (described above with respect to FIG. 4) and into a heat exchanger 504. The heat exchanger 504 is selected, for example, based on an estimated heat load that must be removed from the clean gas stream to achieve a desired temperature. In an embodiment, the heat load can be estimated based on the heat in the process chamber 300, the heat from the blower 406, and the heat from the dehumidifier 502, and the clean gas stream (e.g., air, N 2 The heat exchanger 504 may vary based on the type of gas contained in the clean gas stream (e.g., argon, or nitrogen). One example of a commercially available heat exchanger 504 suitable for use is RV 1.17-0-114.12 available from Becker GmbH (Germany). In an embodiment, the heat exchanger 504 is coupled to a chiller (not shown). Thus, the heat exchanger 504 operates in conjunction with the chiller to remove heat from the clean gas stream and pass it through the chiller and out of the system. Although in various embodiments the heat exchanger 504 is used to remove heat from the clean gas stream (e.g., to reduce the temperature of the clean gas stream), it is contemplated that in embodiments the heat exchanger 504 may be used to heat the clean gas stream (e.g., to increase the temperature of the clean gas stream), such as by flowing hot water through the chiller and transferring heat from the hot water to the clean gas stream.

[0101] Downstream from the heat exchanger, valves 40p and 40r operate to direct the flow of the clean gas stream back to the blower 406 or to the plenum 416. For example, valve 40p can be closed and valve 40r can be opened to recirculate the clean gas stream from the heat exchanger 504 to the blower 406. Such recirculation can, for example, prevent the blower from overheating by allowing gas to bypass the process chamber, particle separator, and filter. Alternatively, valve 40p can be opened and valve 40r can be closed to direct the clean gas stream to the plenum 416. In an embodiment, valve 40r is a throttling valve that regulates or prevents backflow of the clean gas stream to the blower 406. Thus, in an embodiment, valves 40p and 40r can be opened such that a portion of the clean gas stream can be recirculated to the blower 406 while the remainder of the clean gas stream is passed to the plenum 416. Such a configuration can, for example, allow the system to compensate for running the blower at a speed faster than required. In embodiments, valve 40p is an on / off valve that operates to allow or prevent the flow of the clean gas stream along the flow path. In some embodiments, one or both of valves 40p and 40r can operate in response to information received from sensor 44f.

[0102] In the embodiment shown in FIG. 4, the sensor 44f is located upstream of the plenum 416 and downstream of the heating coil 414 (if included) or the condenser system 410. In the embodiment of FIG. 5, the sensor 44f is located downstream of the heat exchanger 504. The sensor 44f is a final check sensor that determines whether the clean gas stream is suitable for delivery to the process chamber 300. Although shown as a single sensor 44f in the embodiment, the sensor 44f can include a pressure sensor, a temperature sensor, a humidity sensor, and / or an oxygen sensor. In some embodiments, a VOC or LEL sensor can be used instead of a humidity sensor. Thus, in an embodiment, the sensor 44f includes a temperature sensor, a pressure sensor, an oxygen sensor, and a humidity sensor. In an embodiment, the sensor 44f includes a temperature sensor, a pressure sensor, an oxygen sensor, and a VOC sensor. In an embodiment, the sensor 44f includes a temperature sensor, a pressure sensor, an oxygen sensor, and a VOC sensor. In an embodiment, the sensor 44f includes a temperature sensor, a pressure sensor, an oxygen sensor, and a LEL sensor. In an embodiment, the sensor 44f includes a temperature sensor, a pressure sensor, and a humidity sensor. In an embodiment, sensor 44f includes a temperature sensor, a pressure sensor, and a VOC sensor. In an embodiment, sensor 44f includes a temperature sensor, a pressure sensor, and a LEL sensor. Other combinations of sensors are contemplated and possible.

[0103] As shown in both FIG. 4 and FIG. 5, the relief valve 40h is positioned along the flow path upstream of the plenum 416. The relief valve 40h allows a volume of the clean gas stream to be exhausted from the environmental system 401, 501 as may be needed to prevent over-pressurization of the process chamber 300. In an embodiment, the relief valve 40h is a mechanical valve that opens when the pressure exceeds a threshold pressure level. For example, the walls of the process chamber may be designed to withstand a certain pressure, and the threshold pressure level may be set based on the limitations of the process chamber. Thus, when the pressure exceeds a threshold pressure level downstream of the blower, the relief valve 40h opens, reducing the pressure throughout the system.

[0104] The plenum 416 provides a flow of the clean gas stream to the linear motion stage 420, as well as to the print head 150 and the recoat head 140. In particular, in various embodiments, the linear motion stage 420 is coupled to the plenum 416 via a valve 40i and a flow meter 42a. In an embodiment, the valve 40i is a pinch valve, although other types of valves are contemplated and possible. The clean gas stream flowing to the linear motion stage 420 provides a positive pressure to the linear motion stage 420, which can prevent contaminants (e.g., build material) from entering a cavity of the linear motion stage 420.

[0105] The print head 150 is coupled to the plenum 416 via valves 40j and 40k and flow meters 42b and 42c. In an embodiment, valve 40j and flow meter 42b are disposed along a flow path between the plenum 416 and a manifold in the print head 150 to provide gas flow for cooling electronics in the print head 150, including the print head substrate, etc. Valve 40k and flow meter 42c are disposed along a flow path between the plenum 416 and a gas flow outlet that, in an embodiment, channels a clean gas stream across an IR lamp disposed on the print head 150 to cool the IR lamp and / or purge a cavity around the IR lamp from contaminants, etc. In an embodiment where the print head does not include an IR lamp, it is contemplated that valve 40k and flow meter 42c may be omitted. In an embodiment, valves 40j and 40k are pinch valves, although other types of valves are contemplated and possible. However, the use of pinch valves allows valves 40j and 40k to be precisely controlled to allow a predetermined flow rate. The flow rate depends on, for example, the number of IR lamps disposed on print head 150, the heat output of the IR lamps, etc. In an embodiment, the flow of the clean gas stream used to cool the electronics in print head 150 is about 10 cubic feet per minute (CFM) to about 15 CFM. In an embodiment, the flow of the clean gas stream for cooling the IR lamps is about 3 CFM to about 5 CFM per lamp.

[0106] The recoat head 140 is coupled to the plenum 416 via a valve 40l and a flow meter 42d, as shown in both FIG. 4 and FIG. 5. In particular, the clean air stream is directed through the valve 40l to the recoat head 140 and to a gas flow outlet that directs the clean gas stream across an IR lamp disposed on the recoat head 140 to cool the IR lamp and / or purge the cavity around the IR lamp from contaminants, etc. In an embodiment where the recoat head does not include an infrared lamp, it is contemplated that the valve 40l and the flow meter 42d may be omitted. In an embodiment, the valve 40l is a pinch valve, although other types of valves are contemplated and possible. As discussed above, the use of a pinch valve allows the valve 40l to be precisely controlled to allow a predetermined flow rate. The flow rate depends, for example, on the number of IR lamps installed in the recoat head 140, the heat value of the IR lamp, etc. In an embodiment, the flow used to cool the electronics is about 10 CFM to about 15 CFM. In embodiments, the flow of the clean gas stream for cooling the IR lamps is from about 3 CFM to about 5 CFM per lamp.

[0107] The clean gas stream enters the process chamber 300 through the linear motion stage 420, the print head 150, and the recoat head 140, although in an embodiment the plenum 416 also provides a separate flow of the clean gas stream to the process chamber 300. In an embodiment, the flow meter 42e and the valve 40m are disposed between the plenum 416 and the process chamber 300. Downstream of the valve 40m is a valve 40n to allow or prevent gas flow to the exhaust. In an embodiment, one or both of the valves 40m and 40n are throttling valves, although other types of valves are possible and contemplated. When both valves 40m and 40n are open, at least a portion of the clean gas stream from the plenum 416 exits the system through the valves. The remaining flow of the clean gas stream enters the process chamber 300 through the inlet.

[0108] 4 and 5 further show a mass flow controller 418 controlling fresh gas flow from the inert air pressure 422 and / or the non-inert air pressure 424. In an embodiment, the mass flow controller 418 is added to the clean gas stream flowing through valve 40m to control the amount of fresh gas provided to the process chamber 300. Fresh gas may be added, for example, when the environment in the process chamber 300 is being transitioned to an inert environment, when the environment in the process chamber 300 is being transitioned to a non-inert environment, or when the clean gas stream reaching the plenum 416 is insufficient to maintain pressure in the closed loop of the environmental system.

[0109] In various embodiments, the inlet to the process chamber 300 is coupled to a diffuser (not shown). While other inlet configurations are possible, the use of a diffuser can minimize pressure drop and allow for uniform flow of gas into the process chamber without adversely affecting the gas flow directly above the powder bed. For example, in embodiments, the inlet to the process chamber 300 may be located vertically above the powder bed (e.g., in the +Z direction in FIG. 1 ) and spaced far enough from the powder bed such that the velocity of the gas stream within about 2 inches of the powder bed is less than about 1 meter per second (m / s). For example, in embodiments, the maximum velocity of gas within 2 inches of the powder bed for a flow of gas (e.g., air or argon) entering the chamber at 200 CFM to 320 CFM is less than 1 m / s, less than 0.9 m / s, or less than 0.85 m / s. Additionally, in embodiments, an inlet to the process chamber 300 may be located toward one side of the process chamber 300 (e.g., above the cleaning station 110 in FIG. 1 ) to further isolate the inlet flow from the region within the process chamber 300 where the build material 400 resides. While the location and configuration of the inlet may vary depending on the particular embodiment, in embodiments the inlet is physically separated from the region where the build material 400 resides, which may reduce the amount of build material that is fluidized within the process chamber 300.

[0110] As shown in Figures 4 and 5, in an embodiment, the process chamber 300 includes at least one sensor 44g. Although shown in Figures 4 and 5 as a single sensor, in an embodiment, the sensor 44g can include, for example, one or more temperature sensors, one or more pressure sensors, one or more oxygen sensors, one or more humidity sensors, one or more VOC sensors, one or more LEL sensors, or any combination thereof. In an embodiment, the process chamber 300 includes at least a temperature sensor and a pressure sensor. In one embodiment, the process chamber 300 includes at least two pressure sensors, at least two oxygen sensors, four temperature sensors, and a humidity sensor, a VOC sensor, or a LEL sensor. The specific location of each of the sensors in the process chamber 300 can vary depending on the particular embodiment. For example, the location of the sensors in the process chamber 300 can vary depending on the number of sensors included, the type of sensors included, the sensitivity of the sensors included, etc. In an embodiment, the temperature sensor in the process chamber 300 is spaced more than about 2 inches from the powder bed.

[0111] In embodiments, the sensor 44g can provide information about the environment within the process chamber 300 that can be used to modify one or more parameters within the closed loop environmental system 401, 501 as may be required to modify the environment within the process chamber 300. For example, according to embodiments, the process chamber 300 can be maintained at a temperature of about 25° C. to about 40° C., or 27° C. to about 35° C., a relative humidity of about 15% to about 40%, and a pressure of about 0 mbar to about 20 mbar. According to embodiments, the process chamber 300 can have an oxygen content of less than 2% by volume when in an inert state and about 15% to about 22% by volume when in a non-inert state. While the specific operating parameters within the process chamber 300 can vary depending on the particular embodiment, it should be understood that the various components of the environmental system described herein work together to achieve and maintain the specific operating parameters during operation of the additive manufacturing apparatus. Such maintenance of the operating parameters, and therefore the environment within the process chamber 300, can be accomplished, for example, through the use of sensors 44 positioned at different locations along the closed loop and, depending on the particular embodiment, using information from the sensors 44 to adjust one or more of the valves 40 to control gas flow to one or more of the components of the environmental system and / or to adjust operating parameters of the blower 406, the concentrator 408, the condenser system 410, the heating coil 414, the dehumidifier 502, and / or the heat exchanger 504. It should be understood that the receipt and processing of information (e.g., information) from the sensors 44, and the determination of what adjustments to make within the environmental system 401, 501 can be performed by the control system 200 or by another computing device included as part of the additive manufacturing apparatus.

[0112] Additionally, in embodiments, information from one or more of the sensors 44 located at different locations along the closed loop may be used to generate an alert regarding the condition of the environmental system. For example, information from one of the sensors may be used initially (e.g., by control system 200) to adjust one or more of the valves to make an adjustment to the environmental system. Following an adjustment, if information from one or more sensors continues to indicate that the environmental system is outside of a predetermined range, control system 200 may generate an alert and / or pause operation of the additive manufacturing device.

[0113] In the embodiment shown in FIG. 4 and FIG. 5, various sensors 44 and valves 40 have been described. It is contemplated that embodiments may include additional sensors 44 and valves 40 throughout the environmental system depending on the particular embodiment. Furthermore, in embodiments, one or more of the sensors 44 and valves 40 described in FIG. 4 and FIG. 5 may be omitted. The sensors 44 and valves 40 may be of types other than those described above. For example, the valve 40 described as an on / off valve may be a throttle valve, or vice versa, and the sensor 44 may include any one or more of the various types of sensors disclosed herein. In an embodiment, the valves 40 may be made of stainless steel and may be coupled with a spring return actuator to control the failure position of each of the valves 40. Furthermore, in an embodiment, one or more of the valves are coupled to a device (e.g., a position sensor) to provide feedback to the control system 200 regarding the position of the valves 40.

[0114] The closed loop of the environmental system 401, 501 further includes tubing or piping that fluidly couples each component in the system to adjacent components. In embodiments, the tubing can be made of stainless steel or another non-reactive material. Along with the valve 40, the tubing is sized to minimize pressure loss throughout the system. In embodiments, the tubing size can also depend on, for example, the flow rate for powder delivery, embedded sensor / device selection, etc.

[0115] 6-7, various embodiments of a particle separation system 402 are shown. In FIGS. 6 and 7, the particle separation system 402 includes at least a first inlet manifold 602a and a second inlet manifold 602b. As described herein, the inlet manifolds may be generally and / or collectively referred to by reference numeral 602 or may be specifically referred to by reference numeral 602 followed by an alphabetic identifier. The embodiment of FIG. 6 includes two inlet manifolds 602a and 602b. The embodiment of FIG. 7 also includes two inlet manifolds 602a and 602b, both of which are obscured in FIG. 7 and not shown. It is contemplated that a greater or lesser number of inlet manifolds may be included depending on the particular embodiment. Additionally, although shown in FIG. 6 as having a rectangular cross-section, it is contemplated that in embodiments the inlet manifold 602 may have a cross-section of any shape depending on the expected flow rates and volumes, as well as the piping and manufacturing considerations connecting the particle separation system 402 to the input source of the particle-containing stream, provided that a single manifold provides gas flow to multiple cyclones, as described in more detail below.

[0116] In various embodiments, the particle separation system 402 further comprises at least a first exhaust manifold 604a and a second exhaust manifold 604b. As described herein, the exhaust manifolds may be generally and / or collectively referred to by reference number 604 or may be specifically referred to by reference number 604 followed by an alphabetic identifier. The embodiments of FIGS. 6 and 7 each include two exhaust manifolds 604a and 604b. It is contemplated that more or fewer exhaust manifolds may be included depending on the particular embodiment. In an embodiment, the number of exhaust manifolds 604 equals the number of inlet manifolds 602. Additionally, although illustrated in FIG. 6 as having a rectangular cross-section and in FIG. 7 as having a trapezoidal cross-section, in an embodiment, depending on the expected flow rates and volumes as well as piping aspects connecting the particle separation system 402 to the particle reduced stream receiving means and manufacturing considerations, it is contemplated that the exhaust manifold 604 may have a cross-section of any shape, where a single manifold receives gas flow from multiple cyclones, as described in more detail below.

[0117] In an embodiment, the inlet manifold 602 is located vertically below (e.g., in the -Z direction) the exhaust manifold 604. A plurality of cyclone separators 605 are disposed along the fluid flow path between each inlet manifold 602 and a corresponding exhaust manifold 604. In various embodiments, the plurality of cyclone separators 605 are arranged in a plurality of arrays 606. As described herein, the arrays may be generically and / or collectively referred to by reference numeral 606 or may be specifically referred to by reference numeral 606 followed by an alphabetical identifier. The embodiment of FIG. 6 includes eight arrays 606a, 606b, 606c, 606d, 606e, 606f, 606g, and 606h, with four arrays disposed between each inlet manifold 602 and its corresponding exhaust manifold 604, and the embodiment of FIG. 7 includes two arrays 606a and 606b, with one array disposed between each inlet manifold 602 and its corresponding exhaust manifold 604. In an embodiment, each array 606 is a substantially linear arrangement of cyclone separators 605 disposed along the length of the corresponding inlet manifold 602 and exhaust manifold 604. In Figure 6, the cyclone separators 605 in each array are arranged in a linear manner, while in Figure 7, the cyclone separators 605 in each array are staggered along a linear axis. Other arrangements of the cyclone separators 605 in each array are contemplated, provided that each cyclone separator 605 is fluidly coupled to the inlet manifold 602 and exhaust manifold 604.

[0118] In an embodiment, multiple arrays 606 are positioned in parallel with other arrays coupled to corresponding inlet manifolds 602 and exhaust manifolds 604. For example, in FIG. 6, arrays 606a and 606b are positioned in parallel with one another. Similarly, in FIG. 7, arrays 606a and 606b are positioned in parallel with one another. The parallel positioning of arrays 606 with respect to inlet manifolds 602 and exhaust manifolds 604 allows multiple arrays 606 to receive equal volumes of gas streams flowing through inlet manifolds 602. However, in an embodiment, it is contemplated that one or more arrays 606 may receive a different volume of gas stream than the other arrays 606.

[0119] It is contemplated that any number of inlet manifolds, outlet manifolds, and arrays of cyclone separators may be included depending on the particular embodiment. Further, it is contemplated that each array may include any number of individual cyclone separators. For example, each array 606 may include 5 or more cyclone separators, 6 or more cyclone separators, 8 or more cyclone separators, 10 or more cyclone separators, 12 or more cyclone separators, or 15 or more cyclone separators. In embodiments, the total number of cyclone separators in the particle separation system is 12 or more, 15 or more, 18 or more, 20 or more, or even 25 or more cyclone separators. The total number of cyclone separators included in the particle separation system 402 may vary depending on, for example, the allowable pressure drop across the particle separation system, the target particle size to be separated, and manufacturing and dimensional considerations of the additive manufacturing apparatus 100. For example, as described in more detail below, it may be desirable to increase the number of cyclone separators to reduce pressure drop, but space considerations may limit the number that can be practically included. In an embodiment, each of the multiple cyclone separators receives a substantially equal volume of the gas stream.

[0120] FIG. 8 is a cross-sectional view of one embodiment of a cyclone separator 605 suitable for use in the particle separation system 402 described herein. As shown in FIG. 8, each cyclone separator 605 includes one or more inlets 802 for a particle-containing stream, an outlet 804 for a particle-reduced stream, a particle outlet 806, and an interior separation chamber 808 bounded by a separator body 810. The separator body 810 has a first end 812, a second end 814, and a peripheral wall 816 extending therebetween. The peripheral wall 816 has an axisymmetric shape and defines the separation chamber 808 having a central axis 818. A particle collection container 706 is provided to collect the separated particles for eventual disposal and to provide closure to the second end 814 of the cyclone separator 605. 7, particle collection container 706 is a common particle collection container 706 shared by the various cyclone separators 605 in the array 606, and in embodiments, multiple arrays 606. Axisymmetric shapes of peripheral wall 816 include cylindrical, frusto-conical, and other shapes of revolution. Although described herein as a cyclone separator 605, other types of separators may be utilized in the particle separation system 402 described herein.

[0121] 8 also illustrates the axisymmetric shape of the peripheral wall 816 of the separator body 810, the inner surface of which defines the separation chamber 808. In the embodiment shown, the peripheral wall has a cylindrical portion 820 and a conical or frusto-conical portion 822. This provides the separation chamber 808 with a tapered converging shape that accelerates the circulatory flow of the incoming particle-containing stream to improve separation of the particles.

[0122] 6-8, in operation, as shown in FIG. 7, all of the incoming particle-containing streams enter the particle separation system 402 through a common fluid inlet 702. Although the fluid inlet 702 is not shown in FIG. 6, it is contemplated that the fluid inlet may be coupled to the particle separation system of FIG. 6 in a manner similar to that shown in FIG. 7. As shown in FIGS. 4 and 5, the fluid inlet 702 may be coupled to a tube or pipe to receive the particle-containing stream from, for example, the process chamber 300 and the recoat head 140. The fluid inlet 702 is in fluid communication with the inlet manifold 602, and in an embodiment, the flow of the particle-containing stream is divided at the fluid inlet 702 to provide a flow through each of the inlet manifolds 602. Specifically, a volume of the particle-containing stream flows into each of the inlet manifolds 602. A portion of the volume of the particle-containing stream enters each of the cyclone separators 605 through the inlet 802 from the corresponding inlet manifold 602 or other source. In an embodiment, the inlet 802 may take the form of a helical (planar) inlet tangent to the inner cylindrical wall of the separator body 810. Other inlet configurations (e.g., helical inlets) may be used depending on the particular embodiment. In an embodiment, the velocity of the particle-containing stream at the inlet is 5 m / s or more, 10 m / s or more, 12 m / s or more, or 15 m / s or more. In an embodiment, the velocity of the particle-containing stream at the inlet is 5 m / s to 20 m / s. The incoming flow then enters the separation chamber 808 near or adjacent to the first end 812 of the separator body 810. The flow of particle-containing stream P enters the page from the inlet 802 across the back of the separation chamber and then begins to circulate inside the separation chamber 808 in a helical path, then is urged forward by the continuous flow of incoming air, gradually moving towards the second end 814 of the separator body. This helical flow pattern tends to force the suspended particles radially outward towards the wall of the separation chamber 808.

[0123] In the configuration shown in FIG. 8, the separation chamber 808 includes a cylindrical portion 820 near the first end 812 of the separator body 810 and a tapered conical portion 822 near the second end 814 of the separator body 810. The tapering of the separation chamber 808 through the use of the conical portion 822 helps to accelerate the flow and direct the suspended particles radially outward toward the wall of the separation chamber 808. Because the outlet 804 is near the first end 812, the airflow circulating within the separation chamber 808 eventually reaches the second end 814 and bends toward the first end 812. Suspended particles thrown radially outward toward the peripheral wall of the separation chamber 808 cannot bend toward the outlet 804 and therefore fall out of suspension and are deposited in the particle collection container 706 that surrounds the second end 814 of the separator body 810, as seen in FIG. 7. The vortex finders 824 extend axially inward from the outlet 804 and help maintain separation between the incoming flow from the inlet 802 and the outgoing flow through the outlet 804 .

[0124] 8, the outlet 804 may be oriented vertically upward, i.e., in a direction opposite to gravity, to utilize gravity in directing the separated particles into the particle collection container 706. However, depending on piping and other installation considerations, in some situations it may be desirable to orient the cyclone separator 605 at an angle other than vertical and to orient the outlet 804 at a position other than vertically upward.

[0125] A volume of the particle-reduced stream flows from the cyclone separator 605 through an outlet 804 to an exhaust manifold 604, which collects the volume of the particle-reduced stream from the cyclone separators 605 in one or more arrays 606. From the exhaust manifold 604, the volume of the particle-reduced stream exits the cyclone separator 605 and flows to a fluid outlet 704. Like the fluid inlet 702, the fluid outlet 704 is omitted from FIG. 6, but it should be understood that the fluid outlet 704 can be coupled to the particle separation system 402 of FIG. 6 in a similar manner as shown in FIG. 7. The volume of the particle-reduced stream from the various exhaust manifolds 604 is combined in the fluid outlet 704 to provide a particle-reduced stream to the next component in the environmental system, such as a filter 404.

[0126] As discussed above, the particular particle separation system 402 used in an environmental system can vary depending on the particular system requirements. In an embodiment, the particle separation system 402 is selected based at least in part on the pressure drop across the particle separation system and / or the cut size of the particle separation system 402. As used herein, the term "pressure drop" refers to the static pressure drop for the same gas content, heat absorption, and blower speed, i.e., the static pressure drop across the particle separation system. As discussed herein above, during operation, the pressure drop across the particle separation system 402 can be obtained by comparing the measured pressure of the particle-containing stream immediately upstream of the particle separation system 402 (e.g., using sensor 44a) with the measured static pressure of the particle-reduced stream immediately downstream of the particle separation system (e.g., using sensor 44b). In an embodiment, the pressure drop is determined by comparing the static pressure of the particle-containing stream immediately upstream of the particle separation system 402 (e.g., using sensor 44b) with the measured static pressure of the particle-reduced stream immediately downstream of the particle separation system. In an embodiment, the pressure drop is determined by comparing the static pressure of the particle-reduced stream immediately downstream of the particle separation system (e.g., using sensor 44b) with the static pressure of the particle-reduced stream immediately downstream of the particle separation system (e.g., using sensor 44c). 2 The pressure drop is measured using a gas flow. In embodiments, the particle separation system 402 has a maximum pressure drop of 1.5 psi or less, 1.0 psi or less, 0.5 psi or less, or 0.3 psi or less. In embodiments, the particle separation system 402 has a maximum pressure drop of about 0.5 psi to about 0.3 psi. Larger pressure drops are contemplated and possible, depending on other components in the environmental system.

[0127] In some embodiments, the pressure drop across the particle separation system is about 30% or less, about 25% or less, or about 20% or less of the maximum pressure drop allowed by the blower. In embodiments, the particle separation system has Air Watts (AW) of less than about 200 AW, less than about 195 AW, or less than about 190 AW, measured according to ASTM F558-13.

[0128] Among other parameters that can be used to control pressure drop, it is believed that increasing the total number of cyclone separators 605 in the particle separation system 402 can decrease the pressure drop, as can increasing the ratio of the total height (H) of the cyclone separators 605 measured from the first end 812 in the separation chamber 808 to the diameter (D) of the cylindrical portion 820 to the narrowest diameter in the separation chamber 808 (e.g., H / D). In embodiments, the ratio of H / D is 4.0 or greater, 4.1 or greater, 4.2 or greater, 4.3 or greater, 4.4 or greater, or 4.5 or greater. In embodiments, the height H of each cyclone separator 605 is 1.0 m or less, 0.9 m or less, 0.8 m or less, 0.7 m or less, 0.6 m or less, 0.5 m or less, or 0.4 m or less. In embodiments, the height H of each cyclone separator is 0.1 m or greater, 0.2 m or greater, 0.3 m or greater, or 0.4 m or greater. In an embodiment, the diameter (D) is 0.25 m or less, 0.2 m or less, 0.15 m or less, or 0.1 m or less. In an embodiment, the diameter (D) is 0.05 m or more, 0.1 m or more, 0.15 m or more, or 0.2 m or more.

[0129] As used herein, the term "cut size" refers to a particle size that is separated at a fractional efficiency of 0.5. In an embodiment, the particle separation system 402 has a cut size of 5 μm or more. In other words, in an embodiment, the particle separation system 402 separates more than 95%, more than 99%, or even more than 99.5% of particles having a particle size of 5 μm or more. In an embodiment, the particle separation system 402 has a cut size of 3.5 μm or more. In other words, in an embodiment, the particle separation system 402 separates more than 95%, more than 99%, or even more than 99.5% of particles having a particle size of 3.5 μm or more. In an embodiment, the particle separation system 402 has a cut size of 1 μm or more as calculated using the Muschelknautz method. In other words, in an embodiment, the particle separation system 402 separates more than 95%, more than 99%, or even more than 99.5% of particles having a particle size of 1 μm or more. Other cut dimensions are contemplated and may vary depending, for example, on the build material 400 used with the additive manufacturing apparatus 100. In an embodiment, the cut size may be determined by comparing the particle size distribution of the particles entering and exiting the particle separation system 402 (e.g., determining the particle size distribution of the particles passing through the particle separation system 402). The particle size distribution may be measured using light scattering according to ASTM B822. The particle size distribution may be measured, for example, using an S3500 particle size analyzer available from Microtrac Inc (Montgomeryville, PA).

[0130] As discussed above, particles separated from the gas flow by the particle separation system 402 are collected in a particle collection container 706 (omitted from FIG. 6 ). As shown in FIG. 7 , multiple cyclone separators 605 are coupled to a common particle collection container 706. In embodiments, the cyclone separators 605 for one or more arrays 606 may be coupled to a common particle collection container 706. Additionally, each particle separation system 402 may include one or more particle collection containers 706. For example, as shown in FIG. 7 , the particle separation system 402 includes two particle collection containers 706, although embodiments may use a single particle collection container, or may use three or more particle collection containers 706. It should also be understood that including additional particle collection containers may limit the number of cyclone separators 605 coupled to each particle collection container, thereby reducing “crosstalk,” but may also result in more valves and actuators, increasing the complexity of their control, as described in more detail below.

[0131] In various embodiments, the particle separation system 402 can be manufactured using additive manufacturing processes, such as those performed by additive manufacturing apparatus 100. The use of additive manufacturing methods can allow for a greater number of cyclone separators 605 and more complex flow paths to be incorporated into the particle separation system 402. Other advantages can be realized by printing the particle separation system 402 using additive manufacturing processes.

[0132] In an embodiment, the particle collection container 706 has at least one sloping surface for guiding particles toward the outlet 709 of the particle collection container 706. Other shapes of the particle collection container 706 are conceivable and possible, so long as the particle collection container 706 is capable of holding a volume of particles. In an embodiment, the volume within the particle collection container 706 is about 10% or more of the volume of build material used by the additive manufacturing device for a complete build. In an embodiment, the outlet 709 of the particle collection container 706 is located at a bottom surface of the particle collection container 706, although other configurations are possible and contemplated. The outlet 709 couples the particle collection container 706 to a valve 40c, which is operable to allow particles to be returned to a material handling system, such as the material handling system 403 of FIGS. 4 and 5.

[0133] In an embodiment, the valve 40c is coupled to an actuator (not shown) configured to move the valve 40c between an open state, in which particles flow through the valve 40c, and a closed state, in which particles are prevented from flowing through the valve 40c. When the valve 40c is closed, particles can collect in the particle collection container 706.

[0134] 7, particle collection container 706 is fluidly coupled to a conduit 708 via valve 40c. In an embodiment, conduit 708 extends between valve 40c and valve 712. In an embodiment, conduit 708 has a first diameter proximate valve 40c that is greater than a second diameter proximate valve 712. Thus, in an embodiment, conduit 708 decreases in diameter along its length between valve 40c and valve 712. However, it is contemplated that in some embodiments, conduit 708 may have a substantially constant volume.

[0135] In an embodiment, valve 712 is coupled to an actuator (not shown) configured to move valve 712 between an open state, in which particles flow through valve 712, and a closed state, in which particles are prevented from flowing through valve 712. When valve 712 is closed, particles entering conduit 708 through valve 712 collect in conduit 708.

[0136] Conduit 708 is fluidly connected to a particle conveyor 710 via valve 712. In embodiments, together with particle separation system 402, particle conveyor 710 can form a particle handling system. In embodiments, particle conveyor 710 is a tube or pipe through which a fluidized flow of gas flows. In embodiments, the fluidized flow of gas entrains particles entering particle conveyor 710 and carries them to material handling system 403. In some embodiments, the return of particles from particle separation system 402 to material handling system 403 can occur during normal operation of additive manufacturing apparatus 100 (e.g., while an object is being built) without causing a pressure drop due at least in part to valves 40c and 712.

[0137] For example, in an embodiment, valves 40c and 712 may be operated (e.g., through their corresponding actuators) to create a pressure lock between particle separation system 402 and particle conveyor 710. Operation of valves 40c and 712 and their corresponding actuators may be controlled, for example, by controller 200 shown in FIG. 2 or by another computing device communicatively coupled to the actuators and valves. Assume that additive manufacturing apparatus 100 is building an object as described above. Assume further that valves 40c and 712 are in a closed position, there is no particle flow between particle collection container 706 and conduit 708, and there is no particle flow between conduit 708 and particle conveyor 710. Thus, conduit 708 is fluidly isolated from particle collection container 706 and particle conveyor 710. A gas stream is directed through the particle conveyor downstream of particle separation system 402. During operation of the additive manufacturing apparatus, the particle-containing stream is directed into a plurality of cyclone separators 605, as described in detail above. In particular, the particle-containing stream is directed through fluid inlet 702 and inlet manifold 602 to multiple cyclone separators 605. At least some particles are separated from the particle-containing stream to produce a particle-reduced stream that is directed from particle separation system 402 through exhaust manifold 604 and fluid outlet 704. At least some particles separated from the particle-containing stream are directed to particle collection container 706, as described in detail above. With valve 40c in the closed position, the particles are accumulated in particle collection container 706.

[0138] In an embodiment, valve 40c fluidly couples particle collection container 706 with conduit 708 and is opened to allow particles to flow from the collection container into conduit 708. In an embodiment, conduit 708 is vertically below valve 40c such that gravity assists the flow of particles from particle collection container 706 into conduit 708. Closing valve 712 causes particles to accumulate in conduit 708.

[0139] After a volume of particles accumulates in the conduit 708, valve 40c is closed, fluidly isolating particle collection container 706 from the conduit 708. Particles from particle separator 402 are redeposited in particle collection container 706 as operation of the additive manufacturing apparatus continues. Once valve 40c is closed, valve 712 is opened to allow particles in the conduit to enter the gas stream of particle conveyor 710. In various embodiments, valve 40c is closed and valve 712 is opened while directing the particle-containing stream to the plurality of cyclone separators 605. In other words, particle separation system 402 is in a continuous state of operation while particles flow from conduit 708 to particle conveyor 710.

[0140] In embodiments, valve 712 remains in the open position until conduit 708 is emptied and particles previously collected in conduit 708 are passed to the gas stream passing through particle conveyor 710. Once conduit 708 is emptied, valve 712 is closed. Valve 40c can then be reopened to allow additional particles from particle collection container 706 to flow into conduit 708. In various embodiments, valve 712 is closed and valve 40c is opened while directing the particle-containing stream to multiple cyclone separators 605. In other words, particle separation system 402 is in a continuous operating state while particles flow from particle collection container 706 to conduit 708.

[0141] It should be appreciated that while particle separation system 402 is in continuous operation during the flow of particles from the particle collection container to conduit 708 and from conduit 708 to particle conveyor 710, in various embodiments at least one of valve 40c and valve 712 is closed during the directing of the particle-containing stream to multiple cyclone separators 605. In other words, at least one of valves 40c and 712 remains closed to fluidly isolate particle separation system 402, specifically multiple cyclone separators 605, from particle conveyor 710. Fluid isolation of particle separation system 402 from particle conveyor 710 maintains pressure within particle separation system 402, and therefore the environmental system.

[0142] Having detailed an additive manufacturing apparatus including an environmental system, it should be understood that in embodiments, the environmental system may be used to enable or improve the operation of the additive manufacturing apparatus. In particular, when the environmental systems of the various embodiments described herein are incorporated into an additive manufacturing apparatus, the environmental system may establish and maintain a stable environment, including an inert environment, such that, for example, the additive manufacturing apparatus can be used in conjunction with chemically reactive build materials. For example, in embodiments, the environmental systems described herein allow for careful control of the environment within a process chamber during operation of the additive manufacturing apparatus.

[0143] In an embodiment, the additive manufacturing device, specifically the environmental system, can operate to transform the environment within the process chamber from a non-inert environment to an inert environment. In such an embodiment, the method includes powering down selected electronic components within the additive manufacturing system. The selected electrical components can include, for example, electrical components that are not certified for use in hazardous environments. These electrical components can include, by way of example and not limitation, non-Atex (non-explosive atmosphere) electrical components that operate at about 5V or above and are disposed within the process chamber.

[0144] Next, the reactive powder is added to a powder supply of the additive manufacturing system. For example, titanium or aluminum powder can be added to a build supply platform or hopper coupled to the recoat head 140. In an embodiment, the reactive powder can be fed to the build supply platform or hopper by a material handling system, such as material handling system 403.

[0145] The method further includes opening at least one valve in an environmental system of the additive manufacturing system to allow gas to be vented from the environmental system. In an embodiment, valve 40n (FIGS. 4 and 5) may be opened to allow gas to be vented from the environmental system.

[0146] The process chamber in the additive manufacturing device is then isolated from the surroundings of the process chamber, in an embodiment, for example, an interlock surrounding the process chamber may be engaged to seal the process chamber.

[0147] Once the process chamber is sealed, an inert gas may be introduced into the process chamber. For example, a mass flow controller 418 may enable fresh gas flow from an inert air pressure 422 to provide a flow of inert gas (e.g., nitrogen or argon) to the process chamber. In embodiments, the inert gas flow may be provided at a low rate, such as about 5 to about 10 CFM.

[0148] In various embodiments, the blower 406 is operated to reduce the oxygen content in the environmental system. For example, the blower may be operated at a speed of about 50 CFM or less to circulate gas in the environmental system. In an embodiment, the blower 406 and the inert air pressure 422 are operated in this manner until all oxygen sensors in the environmental system indicate that the oxygen content in the environmental system is below a predetermined threshold amount for a particular reactive powder. For example, in an embodiment, the blower 406 and the inert air pressure 422 are operated until the oxygen content of the entire environmental system is below about 2 volume percent. In other words, in an embodiment, information regarding the oxygen content in the environmental control system is received from the oxygen sensors in the environmental control system. In response to determining that the oxygen content in the environmental control system is below the threshold, at least one valve (e.g., valve 40n) is closed.

[0149] In embodiments, the oxygen content within the process chamber is maintained, e.g., when a desired oxygen content is reached, in embodiments an exhaust valve (e.g., valve 40n) may be closed to prevent gases from exiting the environmental system.

[0150] Finally, the inert gas (eg, inert air pressure) in the environmental system and the inlet of one of the valves (eg, valve 40n) are adjusted to obtain a predetermined pressure in the process chamber.

[0151] Once the environment in the process chamber is at the desired oxygen content and pressure, the additive manufacturing apparatus can be operated to deposit a layer of reactive powder onto the build surface in the process chamber using a recoat head and selectively spray a binder liquid onto the layer of reactive powder to fuse the layers of the three-dimensional object. In an embodiment, electrical components (e.g., non-Atex components) that were powered down at the start of the passivation process can be powered up when the process chamber is at the desired oxygen content and pressure. The speed of the blower 406 can be increased to about 150 CFM or 200 CFM or more. Other speeds may be appropriate, provided that the blower speed can maintain the desired environment in the process chamber 300. In an embodiment, one or more oxygen sensors disposed in the environmental system can be used to monitor the oxygen content throughout the environmental system. It should be understood that during operation of the additive manufacturing apparatus to build the three-dimensional object, the control system (e.g., control system 200) can adjust various valves and / or parameters of one or more components in the environmental system (e.g., blower, condenser, heat exchanger, etc.) to maintain the steam content, temperature, and oxygen content in the environment in the process chamber.

[0152] In embodiments, when the additive manufacturing apparatus is in an inert state (e.g., the environment in the process chamber is an inert environment), components in the environmental system may be operated to convert the environment in the process chamber to a non-inert environment. For example, in embodiments, selected electrical components (e.g., the non-Atex components described above) are powered down, at least one valve in the environmental system is opened to allow gas to be vented, and non-inert air pressure 424 is used to pump the non-inert gas into the process chamber. In some embodiments, after the build is completed in the inert environment, the blower may be run for several minutes to ensure that the gas in the environmental system has been completely filtered, thereby ensuring that reactive powder is not vented into the environment surrounding the additive manufacturing apparatus. As in the inert process, the non-inert air pressure and blower are operated to flow the non-inert gas into the process chamber and environmental system until a predetermined oxygen content is reached.

[0153] In the embodiments described herein, several components are described as being included in the environmental system. It is contemplated that additional or fewer components may be included, provided that the environment within the process chamber can be controlled within a predetermined tolerance, as may be required by other components within the additive manufacturing apparatus, by the build material, or to achieve a particular quality of the three-dimensional object built by the additive manufacturing apparatus. Thus, it should be appreciated that different types of valves and sensors may be used, and the sensors, valves, and components described herein may be located in various locations throughout the environmental system.

[0154] Based on the above, it should be appreciated that various embodiments of the environmental system and additive manufacturing device including same can enable the additive manufacturing device to print using both reactive and non-reactive materials and to operate in inert and non-inert atmospheres. Additionally, various embodiments described herein allow build material to be captured and reused, and gases within the environmental system can be recirculated to reduce operational costs. Other advantages can be realized depending on the particular embodiment selected.

[0155] Further aspects of the invention are provided by the subject matter of the following appendices.

[0156] (Appendix 1) a process chamber enclosing a print head, a recoat head, and a linear motion stage to which the print head and the recoat head are coupled, the print head and the recoat head operating within the process chamber to build a three-dimensional object by depositing a build material and a binder material; a condenser system fluidly coupled to the process chamber to receive a gas stream having a first vapor content from the process chamber and to provide a gas stream having a second vapor content to the process chamber, the second vapor content being less than the first vapor content; a blower fluidly coupled to the process chamber and the condenser system for flowing a gas stream through a closed loop including the blower, the process chamber, and the condenser system; 1. An additive manufacturing device comprising:

[0157] (Appendix 2) a concentrator fluidly coupled to the condenser system and to the process chamber; 20. The additive manufacturing apparatus of any of the preceding clauses, further comprising:

[0158] (Appendix 3) a VOC (volatile organic compound) sensor along a flow path of the gas stream through said closed loop; 20. The additive manufacturing apparatus of any of the preceding clauses, further comprising:

[0159] (Appendix 4) a LEL (Lower Explosive Limit) sensor along a gas stream flow path through said closed loop; 20. The additive manufacturing apparatus of any of the preceding clauses, further comprising:

[0160] (Appendix 5) a particle separator system disposed within the closed loop to receive a gas stream from the process chamber and provide a gas stream to the blower; Further comprising: The particle separation system is configured to remove particles from a gas stream. 13. An additive manufacturing apparatus according to any preceding claim.

[0161] (Appendix 6) the particle separation system includes a plurality of cyclone separators arranged in a plurality of arrays; 13. An additive manufacturing apparatus according to any preceding claim.

[0162] (Appendix 7) the plurality of cyclone separators includes 12 or more cyclone separators. 13. An additive manufacturing apparatus according to any preceding claim.

[0163] (Appendix 8) 230CFM of air or N 2 a pressure drop across the particle separation system of less than about 1.5 psi when measured using a flow of gas; 13. An additive manufacturing apparatus according to any preceding claim.

[0164] (Appendix 9)

[0165] a process chamber enclosing a print head, a recoat head, and a linear motion stage to which the print head and the recoat head are coupled, the print head and the recoat head operating within the process chamber to build a three-dimensional object by depositing a build material and a binder material; a plurality of first sensors disposed within the process chamber, the plurality of first sensors comprising at least a temperature sensor and a pressure sensor; a particle separation system fluidly coupled to the process chamber for receiving the particle-containing stream from the process chamber, the particle separation system separating at least some particles from the particle-containing stream to generate a particle-reduced stream; and a filter fluidly coupled to the particle separation system to receive a particle-reduced stream from the particle separation system, the filter further removing particles from the particle-reduced stream to provide a clean gas stream; a blower receiving the clean gas stream; a temperature control unit for cooling the clean gas stream; A capacitor system; a plurality of second sensors disposed outside the process chamber along a fluid recirculation path prior to the process chamber and after the particle separation system, the filter, the blower, the temperature control unit, and the condenser system, the plurality of second sensors comprising at least a temperature sensor, a pressure sensor, and one or more of a VOC (volatile organic compound) sensor, a LEL (lower explosive limit) sensor, a humidity sensor, and a vapor sensor; Including, the process chamber, the particle separation system, the filter, the blower, the condenser system, and the temperature control unit form a closed loop. Additive manufacturing equipment.

[0166] (Appendix 10) 13. The additive manufacturing apparatus of any of the preceding claims, wherein the filter is a HEPA (High Efficiency Particulate Air) filter.

[0167] (Appendix 11) a first valve disposed between the particle separation system and the HEPA filter; a second valve disposed along the fluid recirculation path between the blower and the HEPA filter; Further comprising: closing the first valve and the second valve to fluidly isolate the HEPA filter from the closed loop; 13. An additive manufacturing apparatus according to any preceding claim.

[0168] (Appendix 12) the condenser system is disposed along the fluid recirculation path prior to the process chamber and after the pump. 13. An additive manufacturing apparatus according to any preceding claim.

[0169] (Appendix 13) The temperature control unit includes a heat exchanger; the condenser system passes the clean gas stream to the heat exchanger. 13. An additive manufacturing apparatus according to any preceding claim.

[0170] (Appendix 14) a valve capable of bypassing the condenser system along the fluid recirculation path; 20. The additive manufacturing apparatus of any of the preceding clauses, further comprising:

[0171] (Appendix 15) 13. The additive manufacturing apparatus of any preceding clause, wherein the clean gas stream comprises an inert gas.

[0172] (Appendix 16) the environment within the process chamber is inert; 13. An additive manufacturing apparatus according to any preceding claim.

[0173] (Appendix 17) the process chamber includes an inlet diffuser for admitting the clean gas stream into the process chamber; the inlet diffuser reduces the flow velocity of the clean gas stream; 13. An additive manufacturing apparatus according to any preceding claim.

[0174] (Appendix 18) 1. A method for controlling an environment in a process chamber, comprising: receiving information regarding temperature, pressure, and vapor content within the process chamber from at least one sensor disposed within the process chamber; removing the particle-containing stream from the process chamber; separating particles from said particle-containing stream to provide a clean gas stream; reducing the temperature, the vapor content, or both of the clean gas stream based on the received information to achieve a predetermined temperature, pressure, and vapor content in the process chamber; pumping the clean gas stream into a process chamber; Environmental control methods.

[0175] (Appendix 19) Separating the particles from the particle-containing stream includes directing the particle-containing stream through a particle separation system, a HEPA filter, or both. 13. An environmental control method according to any one of the preceding paragraphs.

[0176] (Appendix 20) receiving information regarding a pressure of the clean gas stream from a pressure sensor disposed external to the process chamber; identifying an error in the particle separation system, the HEPA filter, or both based on a difference between a pressure of the clean gas stream and a pressure in the process chamber; 13. An environmental control method according to any one of the preceding paragraphs.

[0177] (Appendix 21) The method of any preceding claim, wherein the clean gas stream is substantially free of oxygen.

[0178] (Appendix 22) The environmental control method of any preceding claim, wherein removing the particle-containing stream from the process chamber comprises removing the particle-containing stream through an outlet port of the process chamber.

[0179] (Appendix 23) The environmental control method of any of the preceding claims, wherein removing the particle-containing stream from the process chamber includes removing the particle-containing stream via a recoat head operating in the process chamber.

[0180] (Appendix 24) The environmental control method of any of the above appended claims, further comprising: receiving information regarding the humidity level of the clean gas stream from a humidity sensor disposed between the process chamber and a dehumidifier; and actuating at least one valve to allow the clean gas stream to bypass the dehumidifier based on the information regarding the humidity level in the process chamber received from the humidity sensor disposed in the process chamber and the humidity level of the clean gas stream.

[0181] (Appendix 25) The method of environmental control of any preceding claim, wherein pumping the clean gas stream into the process chamber includes actuating a throttle valve to allow a predetermined volume of the clean gas stream to enter the process chamber.

[0182] (Appendix 26) 1. A method of operating an additive manufacturing system, comprising: powering off selected electronic components of the additive manufacturing system; adding a reactive powder to a powder of the additive manufacturing system; opening at least one valve of an environmental control system of the additive manufacturing system to allow gas to be vented from the environmental control system; isolating a process chamber of the additive manufacturing system from an ambient atmosphere of the process chamber; introducing an inert gas into the process chamber; activating a blower of the environmental control system to reduce oxygen content in the environmental control system; and adjusting an inert gas inlet and at least one valve to obtain a predetermined pressure in the process chamber.

[0183] (Appendix 27) The method of any of the above clauses, further comprising receiving information regarding the oxygen content of the environmental control system from an oxygen sensor of the environmental control system, and closing at least one valve if it is determined that the oxygen content of the environmental control system is below a threshold value.

[0184] (Appendix 28) The method of any preceding clause, wherein the selected electrical components include electrical components that are not certified for use in hazardous environments.

[0185] (Appendix 29) The method of any preceding clause, further comprising receiving information regarding the oxygen content of the process chamber from an oxygen sensor disposed in the process chamber, and maintaining the oxygen content of the process chamber.

[0186] (Appendix 30) The method of any of the preceding clauses, further comprising depositing a layer of reactive powder with a recoat head onto a build surface of a process chamber equipped with a recoat head, and selectively spraying a binder liquid onto the layer of reactive powder to fuse the layer of the three-dimensional object.

[0187] (Appendix 31) 1. A particle separation system for removing particles from a gas stream, comprising: an inlet manifold; an exhaust manifold; a fluid inlet in fluid communication with the inlet manifold; a fluid outlet in fluid communication with the exhaust manifold; and a plurality of cyclone separators including at least one array of cyclone separators disposed between the inlet manifold and the exhaust manifold.

[0188] (Appendix 32) 1. A particle separation system for removing particles from a gas stream, the particle separation system including: a first inlet manifold and a second inlet manifold; a first exhaust manifold and a second exhaust manifold; a fluid inlet in fluid communication with the first inlet manifold and the second inlet manifold; a fluid outlet in fluid communication with the first exhaust manifold and the second exhaust manifold; and a plurality of cyclone separators comprising a first array of cyclone separators and a second array of cyclone separators, wherein the first array of cyclone separators is disposed between the first inlet manifold and the first exhaust manifold and the second array of cyclone separators is disposed between the second inlet manifold and the second exhaust manifold.

[0189] (Appendix 33) The particle separation system of any preceding clause, wherein each of the plurality of cyclone separators receives an equal volume of the gas stream.

[0190] (Appendix 34) The particle separation system of any of the preceding clauses, wherein the multiple cyclone separators generate a particle-reduced stream and deliver the particle-reduced stream to a fluid outlet.

[0191] (Appendix 35) 13. The particle separation system of any preceding claim, wherein the first array of cyclone separators and the second array of cyclone separators are arranged in parallel.

[0192] (Appendix 36) The particle separation system of any of the preceding clauses, further comprising a collection container, wherein the multiple cyclone separators deliver particles to the collection container.

[0193] (Appendix 37) The particle separation system of any of the preceding clauses, further comprising a conduit and a first valve, the collection container being fluidly coupled to the conduit via the first valve.

[0194] (Appendix 38) A particle handling system comprising: a particle separation system according to any preceding claim; and a particle conveyor, the conduit being fluidly coupled to the particle conveyor via a second valve.

[0195] (Appendix 39) The particle handling system of any of the above appended claims, further comprising a first collection container and a second collection container, wherein the first array of cyclone separators delivers particles to the first collection container and the second array of cyclone separators delivers particles to the second collection container.

[0196] (Appendix 40) The pressure drop across the particle separation system is 230 CFM of air or N 2 A particle separation system according to any preceding clause, wherein the pressure, as measured with a gas flow, is less than 0.5 psi.

[0197] (Appendix 41) The pressure drop across the particle separation system is 230 CFM of air or N 2 A particle separation system according to any preceding clause, wherein the pressure, as measured with a gas flow, is less than 0.3 psi.

[0198] (Appendix 42) The particle separation system of any of the preceding clauses, wherein the plurality of cyclone separators comprises more than 15 cyclone separators.

[0199] (Appendix 43) The particle separation system of any preceding clause, wherein the plurality of cyclone separators comprises more than 20 cyclone separators.

[0200] (Appendix 44) 1. A method for removing particles from a particle-containing gas stream, comprising: flowing a particle-containing gas stream into a particle separation system according to any one of the preceding paragraphs; separating at least some particles from the particle-laden gas stream in the first volume using a first array of cyclone separators fluidly coupled to the first inlet manifold to produce a particle-reduced gas stream in the first volume; separating at least some particles from the particle-laden gas stream in the second volume using a second array of cyclone separators fluidly coupled to the second inlet manifold to produce a particle-reduced gas stream in the second volume; delivering the first volume of the particle-reduced gas stream to a first exhaust manifold coupled to a first array of cyclone separators; delivering the second volume of the particle-reduced gas stream to a second exhaust manifold coupled to a second array of cyclone separators; removing the particle-reduced gas stream from the particle separation system via a fluid outlet coupled to the first exhaust manifold and the second exhaust manifold; method.

[0201] (Appendix 45) The method of any of the above clauses, further comprising collecting at least some of the particles separated from the first volume of the particle-laden gas stream in a first collection container fluidly coupled to the first array of cyclone separators, and collecting at least some of the particles separated from the second volume of the particle-laden gas stream in a second collection container fluidly coupled to the second array of cyclone separators.

[0202] (Appendix 46) The method of any preceding clause, wherein each of the plurality of cyclone separators receives an equal volume of the gas stream.

[0203] (Appendix 47) The method of any of the preceding clauses, wherein the first array of cyclone separators and the second array of cyclone separators are arranged in parallel.

[0204] (Appendix 48) 230CFM of air or N 2 The method of any of the above clauses, wherein the pressure drop across the particle separation system is less than 0.5 psi when measured using gas flow.

[0205] (Appendix 49) 230CFM of air or N 2 The method of any of the above clauses, wherein the pressure drop across the particle separation system is less than 0.3 psi when measured using gas flow.

[0206] (Appendix 50) The method of any of the above clauses, wherein the plurality of cyclone separators comprises more than 15 cyclone separators.

[0207] (Appendix 51) The method of any of the above clauses, wherein the plurality of cyclone separators comprises more than 20 cyclone separators.

[0208] (Appendix 52) 1. A method for collecting particles from a particle-laden gas stream, comprising: directing the gas stream through a particle conveyor downstream from the particle separation system of any of the preceding clauses; The particle separation system further includes a first valve coupled to the collection container, a conduit fluidly coupled to the collection container through the first valve, and a second valve connecting the conduit to a particle conveyor; closing the first and second valves to fluidly isolate the conduit from the collection container and the particle conveyor; directing the particle-laden gas stream through a fluid inlet and an inlet manifold to a plurality of cyclone separators; Separating at least some of the particles from the particle-containing gas stream to produce a particle-reduced gas stream; directing at least some of the particles into a collection container; opening the first valve to allow at least some of the particles in the collection container to flow to the conduit; method.

[0209] (Appendix 53) closing the first valve to fluidly isolate the collection container from the conduit; opening a second valve to allow at least some of the particles in the conduit to enter the gas stream of the particle conveyor; The closing of the first valve and the opening of the second valve occur while directing the particle-laden gas stream to the multiple cyclone separators. 13. A method according to any of the preceding clauses.

[0210] (Appendix 54) closing the second valve to fluidly isolate the conduit from the particle conveyor; opening a first valve to allow at least some of the particles in the collection container to flow into the conduit; the closing of the second valve and the opening of the first valve occur while directing the particle-laden gas stream to the plurality of cyclone separators; 13. A method according to any of the preceding clauses.

[0211] (Appendix 55) The method of any of the preceding clauses, wherein at least one of the first valve and the second valve is closed while directing the particle-laden gas stream to a plurality of cyclone separators.

[0212] (Appendix 56) directing the particulate-laden gas stream to the plurality of cyclone separators includes operating a blower in fluid communication with the particulate separation system; The pressure drop of the particle separation system is 230 CFM of air or N 2 The method of any preceding clause, wherein the pressure drop is less than about 20% of the maximum pressure drop allowed by the blower, as measured using a flow of gas.

[0213] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Accordingly, this specification is intended to cover modifications and variations of the various embodiments described herein, provided that such modifications and variations come within the scope of the appended claims and their equivalents.

[0214] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 107,161, filed October 29, 2020, and entitled "Additive Manufacturing Apparatus Including Environmental System and Method of Use Thereof," which is incorporated by reference in its entirety.

Claims

1. a process chamber enclosing a print head, a recoat head, and a linear motion stage to which the print head and the recoat head are coupled, the print head and the recoat head operating within the process chamber to build a three-dimensional object by depositing a build material and a binder material; a condenser system fluidly coupled to the process chamber for receiving a gas stream having a first vapor content from the process chamber and extracting vapor from the first vapor content to provide a gas stream having a second vapor content to the process chamber, the condenser system including a condensing unit and an evaporator coil, the second vapor content being less than the first vapor content; a blower fluidly coupled to the process chamber and the condenser system for flowing a gas stream through a closed loop including the blower, the process chamber, and the condenser system; a plurality of first sensors disposed within the process chamber, the plurality of first sensors comprising at least a temperature sensor, a pressure sensor, and a humidity sensor; a particle separation system fluidly coupled to the process chamber for receiving the particle-containing stream from the process chamber, the particle separation system separating at least some particles from the particle-containing stream to generate a particle-reduced stream; and a filter fluidly coupled to the particle separation system to receive a particle-reduced stream from the particle separation system, the filter further removing particles from the particle-reduced stream to provide a clean gas stream; a temperature control unit for cooling the clean gas stream; a plurality of second sensors disposed outside the process chamber along a fluid recirculation path prior to the process chamber and after the particle separation system, the filter, the blower, the temperature control unit, and the condenser system, the plurality of second sensors comprising at least a temperature sensor, a pressure sensor, and one or more of a LEL (Lower Explosive Limit) sensor, a humidity sensor, and a vapor sensor; Including, the process chamber, the particle separation system, the filter, the blower, the condenser system, and the temperature control unit form a closed loop; a valve operable to bypass the condenser system along the fluid recirculation path, bypassing the condenser system when the humidity of the gas stream detected by the first sensor does not exceed a threshold value. Additive manufacturing equipment.

2. a concentrator fluidly coupled to the condenser system and to the process chamber; The additive manufacturing apparatus of claim 1 , further comprising:

3. a LEL (Lower Explosive Limit) sensor along the flow path of the gas stream through said closed loop; The additive manufacturing apparatus of claim 1 , further comprising:

4. a particle separator system disposed within the closed loop to receive a gas stream from the process chamber and provide a gas stream to the blower; Further comprising: The particle separation system is configured to remove particles from a gas stream.

10. The additive manufacturing device of claim 1.

5. the particle separation system includes a plurality of cyclone separators arranged in a plurality of arrays; the plurality of cyclone separators includes twelve or more cyclone separators.

5. The additive manufacturing device of claim 4.

6. 230 CFM air or N ２ a pressure drop across the particle separation system of less than about 1.5 psi as measured using a gas flow; 5. The additive manufacturing device of claim 4.

7. the filter is a HEPA (High Efficiency Particulate Air) filter; a first valve disposed between the particle separation system and the HEPA filter; a second valve disposed along the fluid recirculation path between the blower and the HEPA filter; Further comprising: closing the first valve and the second valve to fluidly isolate the HEPA filter from the closed loop; 10. The additive manufacturing device of claim 1.

8. the condenser system is disposed along the fluid recirculation path before the process chamber and after the pump.

10. The additive manufacturing device of claim 1.

9. The temperature control unit includes a heat exchanger; the condenser system passes the clean gas stream to the heat exchanger.

10. The additive manufacturing device of claim 1.

10. the process chamber includes an inlet diffuser for admitting the clean gas stream into the process chamber; the inlet diffuser reduces the flow velocity of the clean gas stream; 10. The additive manufacturing device of claim 1.

11. 2. A method for controlling an environment within a process chamber of an additive manufacturing apparatus according to claim 1, comprising: receiving information regarding temperature, pressure, and vapor content within the process chamber from at least one sensor disposed within the process chamber; removing the particle-containing stream from the process chamber; separating particles from said particle-containing stream to provide a clean gas stream; adjusting the temperature, the vapor content, or both of the clean gas stream based on the received information to achieve a predetermined temperature, pressure, and vapor content in the process chamber; pumping the clean gas stream into the process chamber; Environmental control methods.

12. Separating the particles from the particulate-containing stream includes directing the particulate-containing stream through a particulate separation system, a HEPA filter, or both. The method of controlling an environment according to claim 11.

13. receiving information regarding a pressure of the clean gas stream from a pressure sensor disposed external to the process chamber; identifying a pressure loss in the particle separation system, the HEPA filter, or both based on a difference between a pressure of the clean gas stream and a pressure in the process chamber; The method of controlling an environment according to claim 12.

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