Lower gas stream injection system and method for additive manufacturing systems

Abstract

An additive manufacturing (AM) system (10) includes a housing (18) defining a chamber (20); a build platform (22) disposed in the chamber (20) at a first elevation (150); and a lower gas inlet (98) disposed at a second elevation (152) and configured to supply a lower gas flow (114). The AM system (10) includes a contoured surface (118) extending between the lower gas inlet (98) and the build platform (22) to direct the lower gas flow (114) from the second elevation (152) at the lower gas inlet (98) to the first elevation (150) at the build platform (22), wherein the contoured surface (118) discharges the lower gas flow (98) in a direction (11) substantially parallel to the build platform (22). The AM system (10) also includes one or more gas delivery devices (92) coupled to the lower gas inlet (98) to adjust one or more flow characteristics of the lower gas flow (98); and a gas outlet (132) configured to discharge the lower gas flow (114).

Description

[0001] This application is a divisional application of the invention patent application with application number 201980054644.X filed on August 21, 2019, and invention name “Lower gas flow injection system and method for additive manufacturing system”.

[0002] Priority information

[0003] This application claims priority to U.S. patent application serial number 16 / 107,696, filed on August 21, 2018. Technical Field

[0004] The subject matter disclosed herein relates generally to additive manufacturing systems and methods, and more particularly, to direct laser sintering (DLS) or direct laser melting (DLM) systems and methods that employ focused energy to selectively melt powdered material to produce an object. Background Art

[0005] In contrast to subtractive manufacturing methods, which selectively remove material from an initial form to make an object, additive manufacturing (AM) processes generally involve the accumulation of one or more materials to make a net-shape or near-net-shape object. Although "additive manufacturing" is an industry-standard term (ASTM F2792), it encompasses a wide range of manufacturing and prototyping technologies known by various names, including free-form fabrication, 3D printing, and rapid prototyping / tooling. Special types of AM processes use a focused energy source (e.g., electron beam, laser beam) to sinter or melt powdered material deposited on a build platform in a chamber, thereby forming a solid three-dimensional object in which the particles of the powdered material are bonded together.

[0006] Laser sintering / melting, as used in direct laser sintering (DLS) and / or direct laser melting (DLM), is a general industry term used to refer to methods for producing three-dimensional (3D) objects by sintering or melting fine powders using a laser beam. In particular, laser sintering / melting techniques typically require projecting a laser beam onto a controlled amount of powder (e.g., a powder bed) on a substrate so as to form molten particles or a layer of melted material thereon. When the laser beam interacts with the powder at the powder bed, smoke and / or particulate matter (e.g., condensate, spatter) is generated in the chamber. The smoke and / or certain substances may be detrimental to the quality of the resulting object. For example, suspended smoke and / or certain substances in the chamber may interfere with the laser beam and reduce its energy or intensity before the laser beam reaches the powder bed. As another example, the smoke and / or certain substances may be deposited on the powder bed and may be incorporated into the resulting object.

[0007] In some laser sintering / melting (or DLS / DLM) systems, to remove fumes and / or particulate matter and prevent deposition, a gas stream is introduced into the upper portion of the chamber (e.g., in the z-direction toward the top of the chamber and away from the build platform) to flow generally parallel to the build platform. However, this upper gas stream may not effectively remove fumes and / or particulate matter from the lower portion of the chamber (e.g., in the z-direction toward the build platform and away from the top of the chamber). As a result, particulate matter may become trapped or deposited within the lower portion of the chamber, which can reduce the quality of the resulting object processed by DLS / DLM. Summary of the Invention

[0008] In one embodiment, an additive manufacturing system includes: a housing defining a chamber; a build platform disposed in a lower portion of the chamber at a first elevation relative to the chamber; and a lower gas inlet disposed proximate an upstream end of the chamber, wherein the lower gas inlet is disposed at a second elevation relative to the chamber and is configured to supply a lower gas flow. The additive manufacturing system also includes a contoured surface extending between the lower gas inlet and the build platform. The contoured surface is configured to direct the lower gas flow from the second elevation at the lower gas inlet to the first elevation at the build platform, and to discharge the lower gas flow in a direction substantially parallel to the build platform. The additive manufacturing system also includes: one or more gas delivery devices coupled to the lower gas inlet and configured to adjust one or more flow characteristics of the lower gas flow; and a gas outlet disposed in the downstream end of the chamber, wherein the gas outlet is configured to discharge the lower gas flow from the chamber.

[0009] In another embodiment, a method of operating an additive manufacturing system includes depositing a bed of powder material on a build platform at a first elevation within a chamber; supplying a lower gas flow into a lower portion of the chamber at a second elevation; and directing the lower gas flow along a contoured surface via a fluid guide effect from the second elevation to the first elevation and then toward the build platform in a direction parallel to the build platform. The method also includes applying a focused energy beam to at least a portion of the bed of powder material deposited on the build platform to form a solidified layer.

[0010] In another embodiment, an additive manufacturing system includes a housing defining a chamber; a build platform disposed in a lower portion of the chamber; and a lower gas inlet located a distance above or below the build platform in an upstream end of the chamber, wherein the lower gas inlet is configured to supply a lower gas flow. The additive manufacturing system also includes a contoured surface extending tangentially between the lower gas inlet and the build platform to direct the lower gas flow from the lower gas inlet toward the build platform, wherein the lower gas flow is configured to flow along the contoured surface and be discharged from the contoured surface in a direction substantially parallel to the build platform. The additive manufacturing system also includes: an upper gas inlet disposed in a first sidewall of an upper portion of the chamber and configured to supply an upper gas flow in a direction substantially parallel to the build platform; one or more gas delivery devices coupled to the lower gas inlet and the upper gas inlet and configured to adjust one or more flow characteristics of the lower gas flow and the upper gas flow; and a gas outlet disposed in a second sidewall of the chamber, opposite the first sidewall, wherein the gas outlet is configured to discharge the lower gas flow and the upper gas flow from the chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] These and other features, aspects, and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying drawings, in which like characters represent like parts throughout, and in which:

[0012] Figure 1 is a schematic diagram of an embodiment of an additive manufacturing (AM) system having a manufacturing chamber according to the present embodiment;

[0013] Figure 2 This is a diagram showing the Figure 1 A schematic perspective view of an embodiment of a fabrication chamber of an AM system comprising an upper gas flow arrangement and a lower gas flow arrangement having a contoured surface configured to direct the lower gas flow;

[0014] Figure 3 The diagram shows a configuration with lower gas flow according to this embodiment. Figure 2 A schematic cross-sectional view of an embodiment of an AM system, the lower gas flow arrangement comprising a contoured surface;

[0015] Figure 4 The diagram shows a configuration with lower gas flow according to this embodiment. Figure 2 A schematic cross-sectional view of an embodiment of an AM system, the lower gas flow arrangement including a contoured surface; and

[0016] Figure 5 According to this embodiment, the Figure 2 A flow chart of an embodiment of a process of an AM system. DETAILED DESCRIPTION

[0017] One or more specific embodiments of the present disclosure are described below. In order to provide a brief description of these embodiments, not all features of an actual implementation may be described in the specification. It should be understood that in the development of any such actual implementation (such as in any engineering or design project), many implementation-specific decisions must be made to achieve the developer's specific goals, such as complying with system-related and business-related constraints, which may vary from implementation to implementation. In addition, it should be understood that such development work may be complex and time-consuming, but for ordinary technicians who benefit from this disclosure, it will still be a routine task of design, fabrication, and manufacturing.

[0018] In the following description and claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. As used herein, the term "or" is not meant to be exclusive and refers to instances where at least one of the referenced components is present, and includes instances where combinations of the referenced components may be present, unless the context clearly dictates otherwise. As used herein, the term "uniform gas flow" means that the flow velocity of the gas flow does not vary significantly across the width and / or length of the path of the gas flow. As used herein, the term "additive manufacturing" or "AM" refers to any suitable laser sintering / melting additive manufacturing technology, including but not limited to: direct metal laser melting, direct metal laser sintering, direct metal laser deposition, laser engineered net shape, selective laser sintering, selective laser melting, selective thermal sintering, fused deposition modeling, hybrid systems or combinations thereof.

[0019] The present disclosure generally includes systems and methods for fabricating objects using additive manufacturing methods based on laser sintering / melting. As described above, with such additive manufacturing techniques, when a laser beam sinters or melts a powder bed within an enclosed manufacturing chamber, fumes and / or particulate matter (e.g., condensate, spatter) may accumulate within the chamber. As mentioned, this fumes and / or particulate matter may interact with the laser beam and / or the object being printed and interfere with the fabrication process. Thus, it may be desirable to remove the fumes and / or particulate matter from the chamber to improve the fabrication process and / or the quality of the resulting object.

[0020] As discussed in detail below, embodiments of the present disclosure include additive manufacturing (AM) systems and methods that employ a combination of an upper gas flow in an upper portion of a chamber and a lower gas flow in a lower portion of the chamber, wherein the lower gas flow is directed generally parallel to a build platform of the chamber. The lower gas flow is supplied to the chamber via a lower gas inlet positioned above or below the build platform (e.g., with respect to the z-direction). A contoured surface extends tangentially between the lower gas inlet and the build platform or a surface adjacent to the build platform. Thus, the contoured surface extends from the elevation of the lower gas inlet (e.g., the elevation above or below the build platform) to the elevation of the build platform. For clarity, the term "elevation" as used herein refers to the distance that a component of interest (e.g., the lower gas inlet, the build platform) is vertically disposed above the lower end portion of the AM system. The contoured surface is configured to receive the lower gas flow from the lower gas inlet and direct the lower gas flow to the elevation of the build platform. As described in more detail herein, the contoured surface is configured to induce a flow-guiding effect that directs the lower gas flow from the elevation of the lower gas inlet to the elevation of the build platform. As used herein, the term "fluid guiding effect" includes the Coanda effect (e.g., the tendency of a fluid stream to adhere to an adjacent flat or curved surface) or any other fluid dynamic effect that may affect the flow path of a fluid along a surface. The fluid guiding effect enables the contoured surface to discharge (e.g., deflect, direct, guide) the underlying gas stream in a direction parallel to the build platform.

[0021] The addition of a lower gas stream can advantageously overcome the aforementioned shortcomings of AM systems having only an upper gas stream by more effectively removing smoke and / or particulate matter from the chamber and inhibiting recirculation of smoke and / or particulate matter within the chamber of the AM system. This can significantly reduce or eliminate stagnation and / or deposition of smoke and / or particulate matter at various locations within the chamber, thereby improving the quality of the resulting objects processed by AM. In some embodiments, certain flow characteristics of the lower gas stream can be controlled or adjusted to a desired level that is conducive to generating, for example, a Coanda effect and facilitating the removal of smoke and / or specific substances from the chamber. The flow characteristics can include, but are not limited to, flow rate (e.g., mass flow rate, volume flow rate), flow velocity (e.g., in meters per second (m / s)), flow direction or angle, flow temperature, or any combination thereof. These and other features are described below with reference to the accompanying drawings.

[0022] Figure 1An example embodiment of an AM system 10 (e.g., a laser sintering / melting AM system 10) is shown for producing articles or objects using a focused energy source (e.g., a laser) or beam. For ease of discussion, the AM system 10 and its components will be described with reference to an x-axis or direction 11, a y-axis or direction 13, and a z-axis or direction 15. In the illustrated embodiment, the AM system 10 includes a controller 12 having memory circuitry 14 storing instructions (e.g., software, applications), and processing circuitry 16 configured to execute these instructions to control various components of the AM system 10. The AM system 10 includes a housing 18 defining a fabrication chamber 20 (also referred to herein as chamber 20), which defines an interior volume 21. The chamber 20 is sealed to contain an inert atmosphere and protect the build process from an ambient atmosphere 23 outside the chamber 20. The AM system 10 includes a build platform 22 disposed within the chamber 20 on a bottom surface or bottom wall 24 of the housing 18. Thus, build platform 22 is shown oriented substantially parallel to bottom wall 24 of housing 18. For example, the angle between build platform 22 and bottom wall 24 may be less than 5 degrees (°), less than 3°, or less than 1°. In some embodiments, build platform 22 may have an area of ​​approximately 0.01 square meters (m2). 2 ) and about 1.5m 2 The working area (eg, the top surface of build platform 22) is within the range between . As described below, AM-processed articles or objects are produced on build platform 22.

[0023] AM system 10 includes a powder application device 26 that can be arranged in chamber 20 to repeatedly deposit a certain amount of powder material (e.g., a layer or bed of powder material) onto build platform 22. The powder material deposited on build platform 22 generally forms a powder bed 28. The powder material can include, but is not limited to, polymers, plastics, metals, ceramics, sand, glass, wax, fibers, biological substances, composite materials, or mixtures of these materials. These materials can be used in a variety of forms suitable for a given material and method (including, for example, solid, powder, sheet, foil, tape, filament, pellets, wire, atomized, and combinations of these forms).

[0024] AM system 10 includes an energy generation system 30 that may be disposed inside or outside chamber 20 for generating and selectively directing a focused energy beam 31 (e.g., laser) onto at least a portion of powder bed 28 disposed on build platform 22. Figure 1In the illustrated embodiment, the energy generation system 30 is arranged outside the chamber 20, adjacent to the top surface or top wall 32 of the housing 18, opposite the bottom surface or bottom wall 24. A focused energy beam 31 enters the chamber 20 through a window 34 disposed in the top wall 32. Depending on the desired geometry of the article, the powder bed 28 disposed on the build platform 22 is subjected to the focused energy beam 31 in a selective manner controlled by the controller 12. In some embodiments, the energy generation system 30 includes a focused energy source for generating the focused energy beam 31. In some embodiments, the focused energy source includes a laser source, and the focused energy beam 31 is a laser beam. In some embodiments, the laser source includes a pulsed laser source that generates a pulsed laser beam. In contrast to continuous laser irradiation, a pulsed laser beam is not emitted continuously, but rather is emitted in a pulsed manner (e.g., in pulses with limited time intervals). In some embodiments, the energy generation system 30 includes a plurality of focused energy sources configured to selectively irradiate the powder bed 28 with the focused energy beam 31.

[0025] AM system 10 includes a positioning system 36 (e.g., a gantry or other suitable positioning system) that can be disposed within chamber 20. Positioning system 36 can be any multi-dimensional positioning system, such as a delta robot, a cable robot, a robotic arm, or other suitable positioning system. Positioning system 36 can be operatively coupled to powder application device 26, energy generation system 30, build platform 22, or a combination thereof. Positioning system 36 can move powder application device 26, energy generation system 30, build platform 22, or a combination thereof relative to each other in any of the x-direction 11, y-direction 13, z-direction 15, or a combination thereof.

[0026] The AM system 10 is also configured to supply upper and lower gas flows into the chamber 20 and exhaust the gas flows from the chamber 20, as will be described in detail in the accompanying drawings. Figure 2 The gas stream exhausted or vented from chamber 20 includes an upper gas stream, a lower gas stream, and a substantial portion of any fumes and / or particulate matter generated when focused energy beam 31 is applied to selectively melt or sinter powder bed 28 during formation of a desired article. By utilizing a combination of the upper and lower gas streams described herein, recirculation of fumes and / or particulate matter within the chamber can be significantly reduced or eliminated, thereby significantly improving the build process and / or the quality of the article being printed.

[0027] Figure 2is a schematic perspective view illustrating an embodiment of chamber 20 of AM system 10 according to the present method. As shown, AM system 10 includes a plenum 40 defined by plenum sidewalls 42 and plenum divider wall 44, each extending from sidewall 48 of housing 18 to sidewall 50 along the entire width 52 of chamber 20 in the y-direction 13. Thus, plenum divider wall 44 and plenum sidewall 42 enclose a portion of interior volume 21 of chamber 20 between rear wall 54 and top wall 32 of chamber 20. This enclosed volume is separate from the remaining volume of chamber 20 and will be referred to herein as plenum cavity 56. In the illustrated embodiment, plenum cavity 56 is disposed within an upper portion 60 of chamber 20, which includes any portion or part of chamber 20 disposed vertically above plenum divider wall 44 (e.g., with respect to z-direction 15). For example, in some embodiments, the height 62 of plenum 40 (e.g., the distance between top wall 32 and plenum divider wall 44) may comprise 40%, 50%, 60%, or 70% of the total height 64 of chamber 20. Thus, depending on the vertical position of plenum divider wall 44 in different embodiments, upper portion 60 of chamber 20 may comprise the upper 40%, upper 50%, upper 60%, or upper 70% of chamber 20.

[0028] In the illustrated embodiment, the plenum chamber 56 is fluidly coupled to an upper gas delivery device 66 via an orifice 68 defined in the rear wall 54 of the housing 18. As shown in the illustrated embodiment, the orifice 68 is defined in a portion of the rear wall 54 vertically above the plenum divider wall 44. The upper gas delivery device 66 can be coupled to a gas supply line or any other suitable gas source, which enables the upper gas delivery device 66 to supply a flow of gas to the plenum chamber 56 and, in some cases, pressurize the plenum chamber 56 (e.g., relative to the ambient pressure within the chamber 20). As described in more detail herein, the upper gas delivery device 66 may include an upper flow generation device 70 that includes one or more suitable delivery devices (e.g., one or more fluid valves, one or more pumps or blowers, or a combination thereof) that generates and / or regulates the flow rate and / or pressure of the flow of gas entering the plenum chamber 56. The upper gas delivery device 66 , the upper flow generation device 70 , and the plenum 40 collectively form an upper gas delivery system 72 that is configured to supply an upper gas flow 74 into the chamber 20 .

[0029] For example, as shown, plenum 40 includes a plurality of openings 76 defined within plenum sidewall 42, the plurality of openings 76 collectively defining an upper gas inlet 78 into chamber 20. Thus, the plurality of openings 76 enable pressurized gas within plenum chamber 56 to flow through plenum sidewall 42 and into chamber 20. The plurality of openings 76 may include an array of openings that enable upper gas stream 74 to flow substantially uniformly along x-direction 11 (e.g., parallel to top surface 82 of build platform 22, perpendicular to z-direction 15). The plurality of openings 76 may be sized to adjust certain flow characteristics of upper gas stream 74, such as flow distribution, flow rate (e.g., mass flow rate, volume flow rate), flow velocity (e.g., in meters per second (m / s)), flow direction or angle, or any combination thereof. For example, in some embodiments, the plurality of openings 76 may be sized to substantially facilitate laminar flow of upper gas stream 74 along upper portion 60 of chamber 20. In some embodiments, the plurality of openings 76 may be in the form of circular holes, such as Figure 2 However, in other embodiments, the plurality of openings 76 may be arranged and shaped in a honeycomb-like structure, a sponge-like structure, or any other suitable geometric arrangement to help generate desired flow characteristics for the upper gas flow 74. In further embodiments, the plurality of openings 76 may include a single opening that extends, for example, along a portion of the width 52 of the chamber 20 or substantially all of the width 52.

[0030] It should be noted that although Figure 2In the illustrated embodiment, the upper gas inlet 78 is defined within the plenum sidewall 42, but in other embodiments, the upper gas inlet 78 may be defined within any other suitable portion or portions of the chamber 20. For example, in some embodiments, the plurality of openings 76 are defined within the top wall 32, sidewall 48, sidewall 50, front wall 80, or a combination thereof of the housing 18 in addition to or in place of the plenum sidewall 42. Thus, in certain embodiments, the upper gas inlet 78 may supply the upper gas flow 74 into the chamber 20 at an angle relative to the x-direction 11. In such embodiments, the AM system 10 may include one or more flow-guiding elements disposed within the chamber 20 and configured to receive the upper gas flow 74 from the plurality of openings 76 and redirect the upper gas flow 74 in a direction generally parallel to the x-direction 11. The flow-guiding elements may include one or more winglets, one or more airfoils, or any other suitable flow-guiding system configured (e.g., shaped, oriented) to redirect the flow direction of the upper gas flow 74. In certain embodiments, the plenum 40 can be omitted from the AM system 10, such that the plurality of openings 76 are defined within the rear wall 54 of the housing 18 rather than within the plenum sidewalls 42 of the plenum 40. In such embodiments, the upper gas delivery device 66 can be directly fluidly coupled to the plurality of openings 76, thereby enabling the supply of the upper gas flow 74 through the plurality of openings 76. As described in more detail herein, in further embodiments of the AM system 10, the upper gas delivery system 72 can be entirely omitted from the AM system 10. In such embodiments, the AM system 10 does not include the upper gas flow 74.

[0031] Figure 2The illustrated embodiment of the AM system 10 also includes a lower gas delivery system 90 having a lower gas delivery device 92 including a lower flow generation device 96. The lower flow generation device 96 can be disposed within and / or form a portion of the lower gas delivery device 92. The lower flow generation device 96 includes any suitable delivery device (e.g., one or more fluid valves, one or more pumps or blowers, or a combination thereof) that generates and / or regulates the flow rate and / or pressure of a gas flow supplied by a suitable gas source (e.g., a gas supply line). The lower gas delivery device 92 is fluidly coupled to a lower gas inlet 98 defined within the rear wall 54 of the chamber 20 near the upstream end 100 of the chamber 20. The AM system 10 includes a base plate 102 extending along the length 104 of the chamber 20. The base plate 102 is defined by the bottom wall 24 of the chamber 20 and a lower end portion 106 of the housing 18. A channel 110 is defined within the base plate 102 and fluidly couples the lower gas inlet 98 to a channel outlet 112 defined within the bottom wall 24. As shown in the illustrated embodiment, the channel 110 extends along a length 116 from the lower gas inlet 98 to the channel outlet 112. Thus, the lower gas inlet 98 can receive a lower gas flow 114 from the lower gas delivery assembly 92 and supply the lower gas flow 114 to the chamber 20.

[0032] Channel 110 is partially defined by a contoured surface 118 (e.g., a curved or "S"-shaped surface) that extends tangentially between lower gas inlet 98 and bottom wall 24 adjacent channel outlet 112. As described in greater detail herein, contoured surface 118 is configured to induce a flow-directing effect (e.g., a Coanda effect) in lower gas stream 114, which facilitates discharging lower gas stream 114 from channel outlet 112 in the x-direction 11 (e.g., substantially parallel to build platform 22, substantially parallel to top surface 82 of build platform 22), or in a direction substantially parallel to x-direction 11 (e.g., at ±5 degrees relative to x-direction 11). As described above, the Coanda effect is the tendency of a fluid stream to adhere to adjacent flat or curved surfaces. Thus, the Coanda effect causes lower gas stream 114 to adhere to contoured surface 118 and flow along the length of contoured surface 118. However, the fluid guiding effect may also include any other guiding force configured to redirect the flow trajectory of the fluid, such as static pressure differences and / or dynamic pressure differences along the length and / or width of the fluid flow.

[0033] As shown in the illustrated embodiment, lower gas inlet 98 is oriented transversely (e.g., perpendicularly) to channel outlet 112. For example, because lower gas inlet 98 is defined within rear wall 54, lower gas inlet 98 is disposed within a plane formed by y-axis 13 and z-axis 15. Thus, lower gas inlet 98 is oriented parallel to rear wall 54 such that lower gas inlet 98 is configured to receive lower gas flow 114 in the x-direction 11. Channel outlet 112 is defined within bottom wall 24 and is therefore disposed within a plane formed by x-axis 13 and y-axis 15 and oriented in the z-direction 15. As shown in the illustrated embodiment, rear wall 54 extends perpendicularly or transversely to bottom wall 24. Thus, lower gas inlet 98 is oriented perpendicularly or transversely to channel outlet 112. Even though channel outlet 112 is oriented in the z-direction 15 (e.g., a direction substantially perpendicular to build platform 22), the flow-guiding effect enables lower gas stream 114 to flow along contoured surface 118 (which extends tangentially from lower gas inlet 98 to bottom wall 24) and be discharged from channel outlet 112 in the x-direction 11 that is substantially parallel to build platform 22. More specifically, the flow-guiding effect enables lower gas stream 114 to follow the curvature of contoured surface 118 and, thus, be discharged from channel outlet 112 in a flow direction substantially parallel to x-direction 11 (e.g., a direction oriented ±5 degrees relative to x-direction 11). It should be noted that in other embodiments, the angle between rear wall 54 and bottom wall 24 can be greater than or less than 90 degrees. For example, the angle between rear wall 54 and bottom wall 24 can be between approximately 70 degrees and approximately 110 degrees. Thus, depending on the orientation of rear wall 54 relative to bottom wall 24, the angle between lower gas inlet 98 and channel outlet 112 can be between approximately 70 degrees and approximately 110 degrees.

[0034] After being discharged from channel outlet 112, lower gas stream 114 is directed along lower portion 122 of chamber 20 and flows across build platform 22. For clarity, it should be noted that lower portion 122 of chamber 20 includes any portion of chamber 20, or portion of chamber 20 vertically disposed below plenum divider 44 (e.g., relative to z-axis 15). For example, in some embodiments, lower portion 122 may include the lower 50%, lower 40%, lower 30%, or lower 20% of chamber 20, depending on the position of plenum divider 44 relative to z-axis 15. Regardless, directing lower gas stream 114 across build platform 22 in a direction parallel to build platform 22 (e.g., in the x-direction 11) can mitigate or substantially eliminate undesirable interactions between lower gas stream 114 and powder bed 28 disposed on build platform 22. For example, because lower gas stream 114 is directed parallel across build platform 22 rather than at an angle toward build platform 22 , lower gas stream 114 may not disturb powder bed 28 via eddies and / or pressure fluctuations that may be generated by lower gas stream 114 .

[0035] like Figure 2 In the illustrated embodiment, the lower gas inlet 98 and the channel outlet 112 each include a generally rectangular shape extending along a first width 124 and a second width 126, respectively. In various embodiments, the first width 124 and the second width 126 may each comprise a portion of the width 52 of the chamber 20, or substantially all of the width 52 of the chamber 20. Although the first width 124 and the second width 126 are shown as being equal in the illustrated embodiment, it should be noted that in certain embodiments of the AM system 10, the first width 124 may be greater than or less than the second width 126. For example, in some embodiments, the first width 124 of the lower gas inlet 98 may be relatively small, while the second width 126 of the channel outlet 112 may be relatively large. In such embodiments, the width of the channel 110 may diverge in a downstream direction (e.g., in the x-direction 11) from the lower gas inlet 98 to the channel outlet 112.

[0036] One or more flow-directing elements (e.g., fins, air foils, etc.) can be disposed within the channel 110 and configured to facilitate uniform distribution of the lower gas flow 114 along the second width 126 of the channel outlet 112. Thus, the flow distribution elements can ensure that the flow rate and / or flow velocity of the lower gas flow 114 is substantially uniform across the width 52 of the chamber 20 or a designated portion of the width 52. Although the lower gas inlet 98 and the channel outlet 112 are each illustrated as a single, generally rectangular opening in the illustrated embodiment, it should be noted that the lower gas inlet 98 and the channel outlet 112 can include any suitable number of separate openings. Furthermore, in certain embodiments of the AM system 10, the openings can each have a similar cross-sectional shape or a different cross-sectional shape. For example, the channel outlet 112 can include multiple separate openings configured to adjust certain flow parameters of the lower gas flow 114, similar to the multiple openings 76 of the upper gas inlet 78 discussed above. The channel outlet 112 may include a plurality of circular openings, perforations and / or slots extending along the second width 126 of the channel outlet 112 , or a plurality of openings having any other suitable geometry.

[0037] In further embodiments, the channel 110 may include a plurality of separate channels extending between respective inlets of the lower gas inlet 98 and respective outlets of the channel outlet 112. In other words, the channel 110 may include a plurality of fluidically independent channels disposed adjacent to one another, extending between the lower gas inlet 98 and the channel outlet 112. The plurality of channels may be fluidly coupled to the lower flow generation device 96 using a common manifold or distribution chamber. Thus, the lower flow generation device 96 may supply the lower gas flow 114 to each of the plurality of channels. In some embodiments, one or more flow conditioning elements (e.g., orifice plates, valves, etc.) may be used to facilitate generating a velocity gradient (e.g., a gradient in terms of flow velocity or flow rate) across the lower gas flow 114 (e.g., across the width 52 of the chamber 20). In such embodiments, each channel may be associated with a respective flow conditioning element configured to enable gas of a predetermined flow rate and / or predetermined flow velocity to enter the particular channel.

[0038] As a non-limiting example, flow conditioning elements associated with channels disposed proximate the sidewalls 48, 50 of the chamber 20 can be adjusted so that these channels supply the lower gas flow 114 into the chamber 20 at a first flow velocity and / or a first flow rate. Flow conditioning elements associated with channels disposed proximate the center portion 130 of the chamber 20 (e.g., a portion of the chamber 20 extending near the midpoint of the width 52 along the x-direction 11) can be adjusted so that these channels supply the lower gas flow 114 into the chamber 20 at a second flow velocity and / or a second flow rate. In various embodiments, the first flow velocity and / or the first flow rate can be greater than or less than the second flow velocity and / or the second flow rate. Thus, for such embodiments, the flow conditioning elements enable the AM system 10 to generate a velocity gradient across the lower gas flow 114 (e.g., along the width 52 of the chamber 20) using a single flow generating device (e.g., the lower flow generating device 96). In some embodiments, the AM system 10 may include multiple lower flow generation devices, each of which is coupled to a corresponding channel among the plurality of channels. Thus, each lower flow generation device may be configured to supply a lower gas flow 114 having a predetermined flow rate and / or predetermined flow velocity to a specific channel among the plurality of channels. Thus, in addition to or in lieu of a flow conditioning element, multiple lower flow generation devices may be used to generate a velocity gradient across the lower gas flow 114.

[0039] AM system 10 also includes a gas outlet 132 for exhausting a gas stream 134 from chamber 20, which is disposed in a downstream end 133 of chamber 20. Exhaust gas stream 134 includes upper gas stream 74, lower gas stream 114, and a substantial portion of any smoke and / or particulate matter generated during AM processing. In the illustrated embodiment, gas outlet 132 is disposed in front wall 80 of housing 18, opposite rear wall 54. Gas outlet 132 can be disposed toward lower portion 122 of chamber 20 such that lower gas stream 114 travels tangentially over build platform 22 and through gas outlet 132. However, in other embodiments, gas outlet 132 may be disposed within upper portion 60 of chamber 20. Although illustrated for simplicity in FIG. Figure 2 The shape of the gas outlet 132 is shown as a rectangle in FIG. 1 , but in other embodiments, the gas outlet 132 may be any suitable shape (eg, circular, polygonal, elliptical) that enables sufficient discharge of the gas flow 134 .

[0040] In some embodiments, the gas outlet 132 may include a plurality of openings within the front wall 80 of the housing 18, which may be located near the upper portion 60 of the chamber 20, the lower portion 122 of the chamber 20, or both. The gas outlet 132 may be coupled to a suction mechanism to draw and discharge a gas stream 134 from the chamber 20. In some embodiments, the suction mechanism may also include a filtration system configured to filter the gas stream 134, for example, by removing any fumes and / or particulate matter suspended within the gas stream 134 that has been removed from the chamber 20. After filtering, the gas stream 134 may be directed toward the upper gas delivery device 66 and / or the lower gas delivery device 92 for reuse in the upper and lower gas delivery systems 72, 90. It should be noted that the upper and lower gas streams 74, 114 may include an inert gas (e.g., argon or nitrogen), but may also include any other suitable gas configured to facilitate removal of fumes and / or particulate matter generated during operation of the AM system 10 from the chamber 20.

[0041] As shown in the illustrated embodiment, powder applicator 26 is positioned adjacent to rear portion 138 of chamber 20, proximate sidewall 48. Consequently, interaction between lower gas stream 114 and powder applicator 26 can be significantly reduced, thereby mitigating vortices that may be generated when lower gas stream 114 impinges on powder applicator 26. In some embodiments, AM system 10 includes an additional chamber or compartment positioned adjacent to rear portion 138 of chamber 20 to receive and accommodate powder applicator 26 during periods of inactivity of powder applicator 26 (e.g., during periods when powder applicator 26 is not depositing powder material onto build platform 22). In such embodiments, powder applicator 26 is positioned laterally behind sidewall 48 (e.g., with respect to y-direction 13) during such periods of inactivity, such that powder applicator 26 does not protrude into interior volume 21 of chamber 20. During a deposition period of powder application device 26 (e.g., during a period of time during which powder application device 26 is depositing powder material onto build platform 22), powder application device 26 translates or extends out of the additional chamber and into chamber 20 (e.g., via an aperture defined in sidewall 48). Thus, powder application device 26 can deposit layers of powder material onto build platform 22 continuously. That is, powder application device 26 translates along y-direction 13 to deposit successive layers of powder material. However, as described above, powder application device 26 can also traverse chamber 20 in x-direction 11, z-direction 15, or a combination of x-direction 11, y-direction 13, and / or z-direction 15 while depositing powder material. Regardless, after the deposition period ends, powder application device 26 can return to the additional chamber, thereby removing powder application device 26 from interior volume 21 of chamber 20.

[0042] Figure 3 is a schematic cross-sectional view illustrating an embodiment of chamber 20 of AM system 10 according to the present embodiment. In the illustrated embodiment, upper conduit 140 extends between upper flow generation device 70 and plenum 40, such that upper flow generation device 70 can direct gas 142 (e.g., gas forming upper gas flow 74) from upper gas delivery device 66 to plenum chamber 56 (e.g., through orifice 68 disposed in rear wall 54). In certain embodiments, upper flow generation device 70 can adjust the flow rate of gas 142 supplied to plenum chamber 56 and / or the pressure of gas 142 within plenum chamber 56, which can affect certain flow characteristics of upper gas flow 74. Thus, upper flow generation device 70 can be used to adjust such flow characteristics of upper gas flow 74 in addition to or in lieu of multiple openings 76.

[0043] For example, the target pressure of the gas 142 within the plenum chamber 56 can correspond to a predetermined flow rate and / or a predetermined flow velocity of the upper gas flow 74. Therefore, the target pressure within the plenum chamber 56 can be adjusted to achieve the desired flow rate and / or desired flow velocity of the upper gas flow 74. The magnitude of the target pressure corresponding to the desired flow rate and / or desired flow velocity of the upper gas flow 74 can be predetermined using computer modeling simulations (e.g., via computational fluid dynamics software) and / or empirical testing. For the illustrated embodiment, the AM system 10 includes one or more sensors 144 (e.g., sensor 144a, sensor 144b) configured to measure various operating parameters of the AM system 10. For example, as shown, the plenum 40 includes a sensor 144a disposed within the plenum chamber 56, which is configured to measure a parameter indicating the pressure of the gas 142. The sensor 144a may include a pressure sensor, a pressure gauge, or any other suitable pressure measuring instrument. The upper flow generation device 70 and the sensor 144a are communicatively coupled to the controller 12 via one or more control transmission devices (such as wires, cables, wireless communication devices, etc.). Thus, the controller 12 can receive feedback from the sensor 144a indicating the actual pressure of the gas 142. In some embodiments, the controller 12 compares the actual pressure to a target pressure (e.g., a target pressure previously stored in the memory circuit 14) and, when the actual pressure deviates from the target pressure threshold amount, instructs the upper flow generation device 70 to increase or decrease the flow rate of the gas 142 delivered to the plenum chamber 56 (e.g., by increasing or decreasing the operating speed of the upper flow generation device 70). Thus, the controller 12 can ensure that the flow rate and / or flow velocity of the upper gas flow 74 discharged from the plurality of openings 76 remains substantially similar to the target flow rate and / or target flow velocity of the upper gas flow 74. For example, in some embodiments, the target flow rate can be between approximately 20 and 1200 cubic meters per minute (m 3 / min), between about 80m 3 / min to 800m 3 / min or about 200m 3 / min to 400m 3 / min, and the target flow velocity can be between 0.1 meters per second (m / s) to about 10 m / s, between about 2 m / s to about 8 m / s, or between about 3 m / s to about 5 m / s.

[0044] It should be noted that the sensor 144a is not limited to a pressure sensor, but may include any suitable type of sensor or sensor array that enables the controller 12 to monitor and adjust the flow characteristics of the upper gas flow 74. For example, the sensor 144a may additionally or alternatively include a flow rate sensor, a temperature sensor, a mass flow sensor, or any other suitable sensor configured to provide feedback indicative of the flow characteristics of the upper gas flow 74 to the controller 12. In some embodiments, the sensor 144a may be disposed externally relative to the plenum chamber 56, such as within the chamber 20, near the plurality of openings 76, or within a suitable portion of the upper gas delivery device 66. The controller 12 may use the feedback obtained by the sensor 144a to control the operation of the upper flow generation device 70 in accordance with the techniques discussed above. Additionally, it should be noted that although Figure 3 The illustrated embodiment shows a single flow generating device (e.g., upper flow generating device 70) fluidly coupled to the plenum chamber 56, but the AM system 10 may include two or more flow generating devices, each of which is configured to facilitate flow of gas 142 from the upper gas delivery device 66 into the plenum chamber 56 of the plenum 40.

[0045] In certain embodiments, housing 18 of AM system 10 includes a chamfered portion 146 extending between top wall 32 and front wall 80. Chamfered portion 146 can help direct upper gas stream 74 toward lower portion 122 of chamber 20 (e.g., after upper gas stream 74 flows over build platform 22), so that upper gas stream 74 can exit through gas outlet 132 of chamber 20. Thus, chamfered portion 146 can mitigate the generation of vortices in upper gas stream 74 and / or recirculation of upper gas stream 74 within chamber 20, which could occur if upper gas stream 74 directly impinged on front wall 80. Although chamfered portion 146 is shown as a linear cross-section of housing 18 in the illustrated embodiment, it should be noted that in other embodiments of AM system 10, chamfered portion 146 can include an inclined or curved profile extending between top wall 32 and front wall 80. Additionally, it should be noted that in certain embodiments of the AM system 10 , the angle between the chamfered portion 146 and the front wall 80 (or the angle between the chamfered portion 146 and the top wall 32 ) may be greater than 45 degrees (°) or less than 45°.

[0046] AM system 10 also includes a lower conduit 148 that fluidly couples lower flow generation device 96 to lower gas inlet 98. As described in more detail herein, lower flow generation device 96 can adjust certain flow parameters of lower gas flow 114 to facilitate directing lower gas flow 114 across build platform 22 of AM system 10. It should be noted that in some embodiments of AM system 10, upper flow generation device 70 and lower flow generation device 96 may comprise a common flow generation device configured to supply gas to plenum chamber 56 and lower gas inlet 84. In such embodiments, one or more flow conditioning elements (e.g., orifice plates, valves, baffles, louvers, etc.) can be used to direct gas to plenum chamber 56 and lower gas inlet 98 at respective target flow rates. Thus, gas supplied by the common flow generation device can be used to generate upper gas flow 74 and lower gas flow 114. As described above, in some embodiments, AM system 10 does not include upper gas delivery system 72. Thus, in such embodiments, the AM system 10 includes only the lower flow generation device 96 , or a plurality of lower flow generation devices associated with the lower gas inlet 98 .

[0047] As shown in the illustrated embodiment, build platform 22 is disposed at a first elevation 150 relative to chamber 20, while lower gas inlet 98 is disposed at a second elevation 152 relative to chamber 20. Lower gas inlet 98 is disposed below build platform 22 (e.g., relative to a position along z-axis 15) such that second elevation 152 of lower gas inlet 98 is less than first elevation 150 of build platform 22. In other words, at Figure 3 In the illustrated embodiment, a distance 154 between lower end portion 106 of housing 18 and lower gas inlet 98 is less than a distance 156 between lower end portion 106 and build platform 22. Thus, lower gas inlet 98 is a distance 158 below build platform 22. Contoured surface 118 of channel 110 is configured to receive lower gas flow 114 at a second elevation 152 (at lower gas inlet 98) and to discharge lower gas flow 114 at a first elevation 150 (at build platform 22).

[0048] For example, contoured surface 118 includes a concave portion 160 disposed downstream of lower gas inlet 98 (e.g., relative to the flow direction of lower gas flow 114), followed by a convex portion 162 disposed downstream of concave portion 160. Concave portion 160 is configured to receive lower gas flow 114 from lower gas inlet 98 in the x-direction 11. Concave portion 160 redirects lower gas flow 114 at an intermediate angle 164 relative to lower end portion 106 of housing 18 and build platform 22. In some embodiments, angle 164 may be between approximately 2 degrees (°) and approximately 50°, or between approximately 15° and approximately 35° (e.g., ±5°). Contoured surface 118 may include an intermediate portion 168 that is linear and extends tangentially between concave portion 160 and convex portion 162 at angle 164. Thus, lower gas flow 114 is directed along intermediate portion 168 from second elevation 152 toward first elevation 150. As shown in the illustrated embodiment, protrusion 162 extends tangentially between middle portion 168 and build platform 22. The flow-guiding effect causes lower gas flow 114 to follow the contour of protrusion 162, redirecting lower gas flow 114 from the middle direction to the x-direction 11. Thus, lower gas flow 114 is discharged from contoured surface 118 in the x-direction 11 and flows toward build platform 22.

[0049] In some embodiments, the radius of curvature 170 of the concave portion 160 and the radius of curvature 172 of the convex portion 162 are constant. For example, the radius of curvature 170 of the concave portion 160 and the radius of curvature 172 of the convex portion 172 may comprise a percentage of the width 52 of the chamber 20, a percentage of the height 64 of the chamber 20, a percentage of the length 104 of the chamber 20, or a percentage of any other suitable dimension of the AM system 10. For example, the radii of curvature 170, 172 may comprise between approximately 0.5% and approximately 200% of the length 104 of the chamber 20, between approximately 60% and approximately 2% of the length 104 of the chamber 20, between approximately 50% and approximately 10% of the length 104 of the chamber 20, or between approximately 35% and approximately 25% of the length 104 of the chamber 20. As non-limiting examples, in some embodiments, the radius of curvature 170 of the concave portion 160 and the radius of curvature 172 of the convex portion 162 may each be between about 0.2 centimeters (cm) and about 20 cm, between about 2 cm and about 10 cm, or about 5 cm. It should be noted that in certain embodiments, the radius of curvature 170 of the concave portion 160 may be larger or smaller than the radius of curvature 172 of the convex portion 162. For example, the radius of curvature 172 of the convex portion 162 may be relatively large (e.g., larger than the radius of curvature 170 at the concave portion 160), which may help guide the lower gas flow 114 along the convex portion 162 via a fluid-guiding effect. In further embodiments, the radius of curvature of the concave portion 160, the convex portion 162, or both may be non-linear, such that the slope of the concave portion 160 and / or the slope of the convex portion 162 varies along the length of the contoured surface 118. Generally, the contoured surface 118 is configured to receive the lower gas flow 114 in the x-direction 11 and at the second elevation 152, direct the lower gas flow 114 in the intermediate direction, and utilize a fluid guiding effect to redirect the lower gas flow 114 from the intermediate direction to the x-direction 11. Thus, the lower gas flow 114 may be discharged from the contoured surface 118 at the first elevation 150.

[0050] As described above, in certain embodiments of AM system 10, contoured surface 118 may extend the entire distance between lower gas inlet 98 and build platform 22. In such embodiments, downstream end 176 of contoured surface 118 may abut upstream end 178 of build platform 22. It should be noted that the height of build platform 22 may be negligible, such that the elevation of downstream end 176 of contoured surface 118 is substantially equal to the elevation of top surface 82 of build platform 22 (e.g., first elevation 150). Thus, lower gas flow 114 may be discharged from protruding portion 162 and flow across build platform 22 without substantial obstruction. In other embodiments, build platform 22 may be disposed in a flush position 180, in which it is embedded within or inserted into substrate 102. In such embodiments, the elevation of top surface 82 of build platform 22 is equal to the elevation of downstream end 176 of contoured surface 118. Thus, downstream end 176 of contoured surface 118 and upstream end 178 of build platform 22 are both disposed at first elevation 150. In any event, contoured surface 118 extends from second elevation 152 of lower gas inlet 98 to first elevation 150 of build platform 22, and thereby enables lower gas stream 114 to flow from lower gas inlet 98 toward build platform 22.

[0051] In some embodiments, contoured surface 118 does not extend the entire distance to build platform 22. In such embodiments, a portion of bottom wall 24 is disposed between downstream end 176 of contoured surface 118 and upstream end 178 of build platform 22. This portion of bottom wall 24, referred to herein as spacer portion 182, extends parallel to x-direction 11. Spacer portion 182 increases the separation distance between channel outlet 112 and the powder material disposed on build platform 22. Therefore, during operation of AM system 10, spacer portion 182 can reduce or substantially eliminate the possibility of powder material or other foreign matter entering channel outlet 112 during AM processing. Thus, spacer portion 182 mitigates the accumulation of powder material and / or other foreign matter within channel 110 and on contoured surface 118. In some embodiments, the length of spacer portion can be between 0.5 centimeters (cm) and approximately 3 cm, between approximately 3 cm and approximately 10 cm, or greater than 10 cm. As described above, powder application device 26 can traverse chamber 20 in y-direction 13 to deposit powder material onto build platform 22. That is, the powder application device 26 is substantially parallel to the second width 126 (eg, Figure 2 For such an embodiment, since the powder application device 26 does not traverse the channel outlet 112 during each deposition time period, this configuration can further mitigate undesirable powder deposition within the channel 110.

[0052] As shown in the illustrated embodiment, the AM system 10 includes an intermediate wall 186 that forms the upper portion of the channel 110. The intermediate wall 186 is defined by a portion of the bottom wall 24, a portion of the rear wall 54, and an additional contoured surface 188 extending between these two portions. In some embodiments, the additional contoured surface 188 is offset from the contoured surface 118 by a predetermined offset distance. Thus, the height 190 (e.g., the distance between the contoured surface 118 and the additional contoured surface 188) and the profile of the channel 110 can remain substantially constant along the length of the channel 110. In some embodiments, the offset distance can be between approximately 1 cm and 2 cm. However, in other embodiments, the offset distance can be greater or less than 5 cm. In further embodiments, the height 190 of the channel 110 can be non-uniform, such that the channel 110 converges or diverges (e.g., with respect to the z-axis 15) from the lower gas inlet 98 to the channel outlet 112. As non-limiting examples, the height of the channel 110 near the channel outlet 112 can be approximately half, one-third, or one-quarter the height 190 of the channel 110 near the lower gas inlet 98. Thus, in addition to or in lieu of the lower flow generation device 96, the dimensions of the channel 110 can be used to adjust certain flow parameters of the lower gas flow 114. For example, reducing the height 190 of the channel 110 near the channel outlet 112 can increase the flow velocity and pressure of the lower gas flow 114 discharged from the channel 110. Conversely, increasing the height 190 of the channel 110 near the channel outlet 112 can reduce the flow velocity and pressure of the lower gas flow 114 discharged from the channel 110. Thus, the height 190 of the channel 110 can be adjusted to achieve desired flow characteristics for the lower gas flow 114 and / or enhance the flow directing effect near the channel outlet 112 (e.g., across the protruding portion 162 of the contoured surface 118). Thus, the additional contoured surface 188 can help direct the lower gas flow 114 from the lower gas inlet 98 to the channel outlet 112.

[0053] In some embodiments, in addition to or in lieu of the fluid-directing effect generated by the contoured surface 118, the additional contoured surface 188 may induce an additional fluid-directing effect configured to direct the lower gas flow 114. For example, the additional contoured surface 188 may induce a Coanda effect, or any other fluid dynamic effect (e.g., fluid pressure fluctuations) that helps direct the lower gas flow 114 from the second elevation 152 to the first elevation 150. In further embodiments, the contoured surface 118 and the additional contoured surface 188 may cooperate similar to a pair of cascaded airfoils to direct the lower gas flow 114 along a specific flow trajectory.

[0054] Advantageously, integrating lower gas inlet 98 and channel 110 within base plate 102 of housing 18 can reduce the volume of space occupied by lower gas delivery system 90 within certain portions of chamber 20 (e.g., tool area 196 disposed below plenum 40). For example, because lower gas inlet 98 is disposed below build platform 22 and bottom wall 24 of chamber 20 (e.g., at second elevation 152), tool 197 of AM system 10 and / or other operating equipment of AM system 10 (e.g., one or more replacement build platforms) can occupy substantially all of height 198 of tool area 196 without interfering with lower gas delivery system 90. Furthermore, because tool 197 is disposed upstream of channel outlet 112 (e.g., relative to the flow direction of lower gas stream 114), tool 197 does not obstruct the flow path of lower gas stream 114. Consequently, fluid turbulence within lower gas stream 114 can be reduced or substantially eliminated, allowing lower gas stream 114 to flow across build platform 22 at a substantially uniform flow rate and / or substantially uniform flow velocity. Additionally, integrating the channel outlet 112 into the bottom wall 24 of the chamber 20 allows the bottom wall 24 to remain substantially flat (e.g., parallel to the x-direction 11) along the length 104 of the chamber 20. Thus, the tool 197 of the AM system 10 can be traversed laterally along the length 104 of the bottom wall 24 of the chamber 20 without being obstructed by the lower gas delivery system 90.

[0055] It should be noted that in certain embodiments of AM system 10, intermediate wall 186 may be omitted. In such embodiments, AM system 10 does not include channel 110, but rather includes only contoured surface 118 extending between lower gas inlet 98 and build platform 22. In other words, intermediate wall 186 does not form a channel (e.g., channel 110) between contoured surface 118 and a surface of intermediate wall 186 (e.g., additional contoured surface 188). In further embodiments, lower gas inlet 98 may be disposed above rather than below build platform 22. For example, Figure 4In the illustrated embodiment of AM system 10, lower gas inlet 98 can be positioned vertically above build platform 22 (e.g., relative to z-axis 15). Thus, first elevation 150 of build platform 22 is less than second elevation 152 of lower gas inlet 98. In other words, lower gas inlet 98 is positioned a distance 158 above build platform 22. In such an embodiment, convex portion 162 of contoured surface 118 is positioned upstream of concave portion 160 of contoured surface 118. As discussed above, the flow-guiding effect causes lower gas flow 114 to adhere to the contours of convex portion 192 while being directed across contoured surface 118. Consequently, convex portion 162 redirects lower gas flow 114 entering chamber 20 in the x-direction 11 (e.g., via lower gas inlet 98) toward an intermediate direction (e.g., toward build platform 22). Lower gas stream 114 is then directed along intermediate portion 168 of contoured surface 118 toward bottom wall 24 of chamber 20 and then redirected from the intermediate direction to x-direction 11 via recessed portion 160. Thus, lower gas stream 114 is discharged from recessed portion 160 at an elevation substantially equal to first elevation 150 of build platform 22 and flows across build platform 22 in x-direction 11.

[0056] Return now Figure 3 In some embodiments, the controller 12 is communicatively and operably coupled to the lower flow generation device 96 and can be configured to instruct the lower flow generation device 96 to maintain a desired flow rate and / or desired flow velocity of the lower gas flow 114 during operation of the AM system. In some embodiments, the desired flow rate and / or desired flow velocity are predetermined and correspond to a flow rate and / or flow velocity of the lower gas flow 114 that enhances the effect of the fluid guiding effect. Thus, the controller 12 can ensure that the lower gas flow 114 is directed along the protrusion 162 during operation of the AM system 10, thereby mitigating the possibility of flow separation between the lower gas flow 114 and the protrusion 162. For example, computer simulation tools (e.g., computational fluid dynamics software) and / or empirical testing can be used to determine a target flow rate and / or target flow velocity of the lower gas flow 114 that enhances the fluid guiding effect (e.g., a flow rate and / or flow velocity at which substantially all of the lower gas flow 114 is redirected by the protrusion 162 of the contoured surface 118). The target flow rate and target flow velocity may be stored in the memory circuit 14 of the controller 12. In some embodiments, the target flow rate may be between approximately 20 and 2000 cubic meters per minute (m3 / min). 3 / min), at about 80m 3 / min to 800m 3 / min, or about 300m 3 / min to 400m 3 / min, and the target flow velocity may be between 0.1 meters per second (m / s) and approximately 15 m / s, between approximately 2 m / s and approximately 10 m / s, or between approximately 3 m / s and approximately 8 m / s. The controller 12 may monitor the actual flow rate and / or actual flow velocity of the lower gas stream 114 using the sensor 144b during operation of the AM system 10, and may adjust the operating speed of the lower flow generating device 96 so that the actual flow rate and / or actual flow velocity of the lower gas stream 114 is maintained within the target flow rate and / or the tolerance of the target flow velocity.

[0057] For example, the sensor 144b may be disposed within a portion of the lower gas delivery assembly 92, the lower conduit 148, the passage 110, or any other suitable portion of the AM system 10. The sensor 200 may include a flow rate sensor, a flow velocity monitor, a mass flow sensor, or any other suitable sensor configured to provide feedback to the controller 12 indicating an actual flow rate and / or an actual flow velocity of the lower gas flow 114. For example, in some embodiments, if the actual flow rate and / or the actual flow velocity of the lower gas flow 114 deviates from a target flow rate and / or a target flow velocity by more than a predetermined threshold amount, the controller 12 instructs the lower flow generation assembly 96 to increase or decrease the flow rate and / or the flow velocity of the lower gas flow 114 (e.g., by increasing or decreasing the operating speed of the lower flow generation assembly 96) so that the actual flow rate and / or the actual flow velocity of the lower gas flow 114 approach the target flow rate and the target flow velocity, respectively.

[0058] In some embodiments, the controller 12 adjusts the flow rate and / or flow velocity of the lower gas stream 114 based on the thermodynamic properties of the lower gas stream 114, the composition of the lower gas stream 114, or both. For example, the surface temperature of the contoured surface 118, the temperature of the lower gas stream 114, and / or the composition of the lower gas stream 114 may affect the target flow rate and / or target flow velocity of the lower gas stream 114 at which the flow directing effect is enhanced. Similar to the discussion above, computer simulation tools, empirical testing, or both may be used to determine the correlation between the thermodynamic and compositional properties of the lower gas stream 114 and the stability of the flow directing effect (e.g., the ability of the lower gas stream 114 to adhere to the protrusion 162). The correlation between the thermodynamic and compositional properties of the lower gas stream 114 and the corresponding target flow rate and target flow velocity of the lower gas stream 114 may be stored in the memory circuit 14 (e.g., as an equation, a lookup table, etc.).

[0059] Similar to the discussion above, controller 12 may monitor the thermodynamic and compositional properties of lower gas flow 114 via sensor 144b during operation of AM system 10 to determine whether adjustments to the flow rate and / or flow velocity of lower gas flow 114 are desirable. For example, sensor 144b may further include, but is not limited to, temperature sensors such as thermocouples, resistance temperature detectors, or thermistors, and gas detector sensors such as electrochemical sensors, ultrasonic sensors, or particle / smoke sensors. Controller 12 may compare the actual flow rate and / or actual flow velocity of lower gas flow 114 to see if they correspond to respective target values ​​for the flow rate and / or flow velocity associated with the measured thermodynamic and compositional properties of lower gas flow 114. If the actual flow rate and / or actual flow velocity of lower gas flow 114 deviates from the target flow rate and / or target flow velocity, controller 12 instructs lower flow generation device 96 to increase or decrease the flow rate and / or flow velocity of lower gas flow 114 so that the actual flow rate and / or actual flow velocity of lower gas flow 114 approaches the target value. Thus, the controller 12 can ensure that the flow guiding effect within the lower gas stream 114 is maintained during operation of the AM system 10. Additionally or otherwise, the controller 12 can use feedback generated by the sensor 144b indicative of any suitable operating parameter of the AM system 10 to adjust the flow rate and / or flow velocity of the lower gas stream 114, the upper gas stream 74, or both.

[0060] Considering the foregoing, Figure 5 is a flow chart of an embodiment of process 210 so that the AM system 10 can be operated during the production of an article. The following discussion refers to the entire Figure 1-4 It should be noted that one or more steps of process 210 may be stored in memory circuit 14 and executed by processing circuit 16 of controller 12. Figure 5 In the illustrated embodiment, process 210 begins (step 212) by depositing a quantity of powder material onto build platform 22 within chamber 20 of AM system 10. For example, controller 12 instructs powder applicator 26 to deposit powder material onto build platform 22. Controller 12 instructs positioning system 36 to move powder applicator 26 and / or build platform 22 relative to each other along x-axis 11, y-axis 13, z-axis 15, or a combination thereof to any suitable position to deposit powder material in a layer-by-layer manner during each deposition time period of powder applicator 26.

[0061] The illustrated embodiment of process 210 continues (step 214) by supplying lower gas stream 114 into chamber 20. For example, controller 12 instructs an associated gas delivery system (e.g., lower gas delivery system 90) to supply lower gas stream 114 into chamber 20 (e.g., via lower gas inlet 98). By way of specific example, controller 12 instructs lower gas delivery system 90 to control flow characteristics of lower gas stream 114, such as flow profile, flow rate (e.g., mass flow rate, volume flow rate), flow temperature, or any combination thereof. The method includes (step 216) directing lower gas stream 114 from second elevation 152 of lower gas inlet 98 to first elevation 150 of build platform 22 along contoured surface 118. For example, as discussed above, contoured surface 118 is configured (e.g., shaped, arranged) to induce a flow directing effect such that convex portions 162 of contoured surface 118 can be used in conjunction with concave portions 160 to adjust the flow direction of lower gas stream 114. Thus, convex portion 162 and concave portion 160 of contoured surface 118 can cooperate to direct lower gas flow 114 from second elevation 152 to first elevation 150. In some embodiments, controller 12 can adjust the flow rate of lower gas flow 114 (e.g., via lower flow generation device 96) so that the actual flow rate of lower gas flow 114 is substantially equal to the target flow rate that facilitates generating the fluid directing effect. For example, if the actual flow rate of lower gas flow 114 exceeds or falls below the target flow rate by a threshold amount, the fluid directing effect may not adequately direct lower gas flow 114 along the curvature of convex portion 162, causing lower gas flow 114 to be discharged into chamber 20 turbulently and not traverse substantially parallel to build platform 22. Thus, controller 12 can ensure that the fluid directing effect is maintained during a desired portion of the operation of AM system 10 by maintaining the actual flow rate of lower gas flow 114 substantially similar to the target flow rate. In certain embodiments, the controller 12 also instructs the lower gas delivery system 90 to control the content of the lower gas flow 114 (eg, argon, nitrogen, any other suitable inert gas, or a combination thereof).

[0062] In the embodiment shown, process 210 includes (step 218) supplying an upper gas flow into chamber 20. For example, controller 12 instructs an associated gas delivery system (e.g., upper gas delivery system 72) to supply an upper gas flow 74 into chamber 20. By way of specific example, controller 12 instructs upper gas delivery system 72 to control flow characteristics of upper gas flow 74, such as flow distribution, flow rate (e.g., mass flow rate, volume flow rate), flow temperature, or any combination thereof. In certain embodiments, controller 12 instructs upper gas delivery system 72 to control the content of upper gas flow 74 (e.g., argon, nitrogen, any other suitable inert gas, or a combination thereof). As described above, certain embodiments of AM system 10 do not include upper gas delivery system 72. Therefore, in such embodiments, process 210 does not include step 218.

[0063] In some embodiments, the controller 12 can instruct the upper gas delivery system 72 and the lower gas delivery system 90 to control the flow rates of the upper gas stream 74 and the lower gas stream 114 so that the ratio between the two gas flow rates is controlled to a desired value or range. For example, in some embodiments, the flow rate of the lower gas stream 114 is between about 10 times and about 1.5 times the flow rate of the upper gas stream 74, between about 9 times and about 7 times the flow rate of the upper gas stream 74, or about 8 times the flow rate of the upper gas stream 74. In certain embodiments, the ratio between the lower gas stream 114 and the upper gas stream 74 can be adjusted to facilitate exhaustion of smoke and / or particulate matter from the chamber 20 via the gas outlet 132.

[0064] The illustrated embodiment of process 210 includes (step 220) selectively applying a focused energy beam to a quantity of powder material deposited on build platform 22. For example, controller 12 instructs energy generation system 30 to apply focused energy beam 31 (e.g., a laser beam) to a portion of powder bed 28. While supplying upper and / or lower gas streams 74, 114, focused energy beam 31 selectively melts and / or sinters the powder material of powder bed 28 in a predetermined manner to form a solidified layer.

[0065] In some embodiments, supplying the lower gas stream 114 in step 214, directing the lower gas stream 114 along the contoured surface 118 in step 216, and supplying the upper gas stream 74 in step 218 may be performed simultaneously. In some embodiments, supplying the lower gas stream 114 in step 214 and directing the lower gas stream 114 along the contoured surface 118 in step 216 may be performed before or after supplying the upper gas stream 74 in step 218. In some embodiments, applying the focused energy beam 31 in step 220 may be performed simultaneously with supplying the lower gas stream 114 in step 214, directing the lower gas stream 114 along the contoured surface 118 in step 216, and supplying the upper gas stream 74 in step 218. In some embodiments, applying the focused energy beam 31 in step 220 may be performed before supplying the lower gas stream 114 in step 214 and directing the lower gas stream 114 along the contoured surface 118 in step 216, or before supplying the upper gas stream 74 in step 218. In some embodiments, process 210 may repeat steps 212, 214, 216, 218, and 220 to form an additional solidified layer on a previously formed solidified layer. In some embodiments, process 210 may include performing steps 214, 216, and 218 each time after performing step 220. In some embodiments, process 210 may include repeating steps 212, 214, 216, 218, and 220 multiple times to form successive additional solidified layers to form a desired article (e.g., applying the focused energy beam 31 in step 220 may be performed continuously while supplying the lower gas stream 114 in step 214, directing the lower gas stream along the contoured surface 118 in step 216, and supplying the upper gas stream 74 in step 218).

[0066] The technical effects of the present disclosure include improving the performance and efficiency of an AM system by removing fumes and / or other particulate matter generated during AM processing from the chamber. The disclosed AM system utilizes a combination of an upper gas flow, supplied from the sidewalls in the upper portion of the chamber and directed substantially parallel to the build platform, and a lower gas flow, supplied from below or above the build platform and directed toward the build platform via a contoured surface. The contoured surface is configured to utilize a fluid-guiding effect to direct the lower gas flow from the lower gas inlet to the build platform, such that the lower gas flow is directed across the build platform in a direction substantially parallel to the build platform. Introducing the lower gas flow into the chamber via the contoured surface reduces the volume occupied by the lower gas delivery system within the chamber, thereby increasing the available volume within the AM system's chamber. Furthermore, directing the lower gas flow substantially parallel to the build platform mitigates interaction between the lower gas flow and the powder bed disposed on the build platform. Consequently, the combination of the upper and lower gas flows can significantly reduce or eliminate gas recirculation within the chamber and facilitate the removal of fumes and / or particulate matter from the chamber through the AM system's exhaust outlet.

[0067] This written description uses examples to disclose the invention, including the best mode, and also to enable those skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. If such other examples have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims, then these other examples are intended to fall within the scope of the claims.

Claims

1. An additive manufacturing system (10), characterized in that include: a housing (18), said housing (18) defining a chamber (20); a building platform (22) disposed in a lower portion (122) of the chamber (20); a lower gas inlet (98) located a distance above or below the build platform (22) in the upstream end (100) of the chamber (20) and configured to supply a lower gas flow (114); a contoured surface (118) extending tangentially between the lower gas inlet (98) and the build platform (22) and configured to direct the lower gas flow (114) from the lower gas inlet (98) toward the build platform (22), wherein the lower gas flow (114) is configured to flow along the contoured surface (118) and to be discharged from the contoured surface (118) in a direction (11) substantially parallel to the build platform (22); an upper gas inlet (78) disposed in a first sidewall (54) of an upper portion (60) of the chamber (20) and configured to supply an upper gas flow (74) in the direction (11) substantially parallel to the build platform (22); one or more gas delivery devices coupled to the lower gas inlet (98) and the upper gas inlet (78) and configured to adjust one or more flow characteristics of the lower gas flow (114) and the upper gas flow (74); and A gas outlet (132) is provided in a second side wall (80) of the chamber (20) opposite the first side wall (54), wherein the gas outlet (132) is configured to discharge the lower gas flow (114) and the upper gas flow (74) from the chamber (20).

2. The additive manufacturing system (10) according to claim 1, characterized in that in, The contoured surface (118) includes a concave portion (160) disposed upstream of the convex portion (162) and downstream of the lower gas inlet (98), wherein a middle portion of the contoured surface (118) extends tangentially between the concave portion (160) and the convex portion (162) at an angle relative to the building platform (22).

3. The additive manufacturing system (10) according to claim 2, characterized in that in, The radius of curvature (170) of the concave portion (160) and the radius of curvature (172) of the convex portion (162) are each between 0.5% and 200% of the length (104) of the chamber (20).

4. The additive manufacturing system (10) according to any one of claims 1 to 3, characterized in that in, The lower gas flow (114) is directed along the contoured surface (118) via the Coanda effect.

5. The additive manufacturing system (10) according to any one of claims 1 to 3, characterized in that An additional contoured surface (188) is included, the additional contoured surface (188) being offset a distance (190) from the contoured surface (118) to define a channel (110) extending a length from the lower gas inlet (98) to a channel outlet (112) defined in a bottom wall (24) of the chamber (20).

6. The additive manufacturing system (10) according to any one of claims 1 to 3, characterized in that include: a sensor (144b), the sensor (144b) being in fluid communication with the lower gas stream (114); a flow generating device (96) of the one or more gas delivery devices, wherein the flow generating device (96) is configured to generate the lower gas flow (114); and A controller (12) comprising a processor (16) and a memory (14), wherein the processor (16) is communicatively coupled to the sensor (144b) and the flow generation device (96), wherein the processor (16) is configured to receive feedback from the sensor (144b) indicative of a flow parameter of the lower gas flow (114), and wherein the processor (16) is configured to adjust an operating speed of the flow generation device (96) when the flow parameter deviates from a target parameter by a predetermined threshold amount.

7. The additive manufacturing system (10) according to claim 6, characterized in that in, The flow parameters include a flow rate of the lower gas flow (114), a flow velocity of the lower gas flow (114), a temperature of the lower gas flow (114), a composition of the lower gas flow (114), or a combination thereof.

8. A method for additive manufacturing of an object, characterized in that include: A build platform (22) is provided in a lower portion (122) of a chamber (20) defined by the housing (18); depositing a bed of powdered material (28) on the build platform (22) at a first elevation (150) within the chamber (20); positioning a lower gas inlet (98) a distance above or below the build platform (22) in the upstream end (100) of the chamber (20), the lower gas inlet (98) supplying a lower gas flow (114) to the chamber (20); directing the lower gas flow (114) from the lower gas inlet (98) toward the build platform (22) via a contoured surface (118) extending tangentially between the lower gas inlet (98) and the build platform (22), the lower gas flow (114) flowing along the contoured surface (118) and being discharged from the contoured surface (118) in a direction (11) substantially parallel to the build platform (22); providing an upper gas inlet (78) in a first side wall (54) of an upper portion (60) of the chamber (20), the upper gas inlet (78) supplying an upper gas flow (74) in the direction (11) substantially parallel to the building platform (22); adjusting one or more flow characteristics of the lower gas stream (114) and the upper gas stream (74) via one or more gas delivery devices coupled to the lower gas inlet (98) and the upper gas inlet (78); and A focused energy beam is applied to at least a portion of the bed of powder material (28) deposited on the build platform (22) to form a solidified layer.

9. The method according to claim 8, characterized in that in, The lower gas flow (114) is directed along the contoured surface (118) via the Coanda effect.

10. The method according to claim 8, characterized in that in, The contoured surface (118) includes a concave portion (160) disposed upstream of a convex portion (162), wherein a mid-portion of the contoured surface (118) extends tangentially between the concave portion (160) and the convex portion (162) at an angle relative to the build platform.

11. The method according to any one of claims 8 to 10, characterized in that Further including: The lower gas stream (114) and the upper gas stream (74) are discharged from the chamber (20) via a gas outlet (132) provided in a second side wall (80) of the chamber (20) opposite the first side wall (54).

12. The method according to any one of claims 8 to 10, characterized in that in, Supplying the lower gas flow (114) includes supplying the lower gas flow (114) at a first flow velocity, the first flow velocity being between 1 meter per second and 15 meters per second.

13. The method according to any one of claims 8 to 10, characterized in that Further comprising adjusting the operating speed of the one or more gas delivery devices when a flow parameter of the lower gas stream (114) deviates from a target parameter by a predetermined threshold amount.

14. The method according to claim 10, characterized in that in, The radius of curvature (170) of the concave portion (160) and the radius of curvature (172) of the convex portion (162) are each between 0.5% and 200% of the length (104) of the chamber (20).

15. The method according to any one of claims 8 to 10, characterized in that in, Supplying the upper gas flow (74) includes supplying the upper gas flow (74) at a flow velocity between 0.1 meters per second and 10 meters per second.

Images