WO2022140198A1

WO2022140198A1 - Systems and methods of powder delivery for additive manufacturing

Info

Publication number: WO2022140198A1
Application number: PCT/US2021/064185
Authority: WO
Inventors: Lexian GUO; Matthew David Rosa
Original assignee: Nikon Corporation
Priority date: 2020-12-23
Filing date: 2021-12-17
Publication date: 2022-06-30

Abstract

Additive manufacturing systems are described with temperature control systems, suspension systems, and/or couplings between the powder container and a stationary frame of the system that facilitate vibration of the powder container and agitation of powder in the powder container. A powder supply assembly for an additive manufacturing system that manufactures an object on a build platform from a powder can include a powder container configured to retain a powder and having a supply outlet facing the build platform, and a flow control assembly configured to control a flow of powder from the powder container toward the build platform. Wherein the powder container comprises a temperature control element to maintain the powder container within a selected temperature range.

Description

SYSTEMS AND METHODS OF POWDER DELIVERY FOR ADDITIVE

MANUFACTURING

CROSS REFERENCE TO RELATED APPLICATION

[001] The present application claims the benefit of U.S. Provisional Application No. 63/130,075, filed December 23, 2020. The entire disclosure of U.S. Provisional Application No. 63/130,075 is incorporated herein by reference.

FIELD

[002] The present disclosure pertains to systems and methods of powder delivery for additive manufacturing systems.

BACKGROUND

[003] Additive manufacturing systems or three-dimensional printing systems are used to print three-dimensional objects. Existing three-dimensional printing systems are relatively slow, have a low throughput, are expensive to operate, and/or generate excessive waste. There is a never-ending search to increase the speed, the throughput and reduce the cost of operation for three-dimensional printing systems.

[004] In many additive manufacturing systems, material is applied to the object or workpiece in layers, and fused with the object by, for example, application of heat. Materials such as fine powders can adhere or clump together in supply containers or hoppers, making it difficult to evenly deposit powder layers on the part and maintain consistent powder flow. Additionally, temperature control of the powder delivery system components and the powder itself can present challenges when those components are in thermal contact with the heat source used to fuse the material onto the workpiece. Accordingly, there exists a need for improved additive manufacturing systems.

SUMMARY

[005] Certain embodiments of the disclosure pertain to additive manufacturing systems with coolant circuits, suspension systems, and couplings between the powder container and stationary frame members of the system that facilitate vibration of the powder container and agitation of powder in the powder container. In a representative embodiment, a powder supply assembly for an additive manufacturing system that manufactures an object on a build platform from a powder comprises a powder container configured to retain a powder and having a supply outlet facing the build platform, and a flow control assembly configured to control a flow of powder from the powder container toward the build platform, wherein the powder container comprises a temperature control element to maintain the powder container within a selected temperature range.

[006] In any or all of the disclosed embodiments, the temperature control element is configured to maintain the powder container at a selected temperature below a sintering temperature of the powder.

[007] In any or all of the disclosed embodiments, the temperature control element is configured to maintain the powder container at a temperature of 100° C or greater.

[008] In any or all of the disclosed embodiments, the temperature control element includes a heater.

[009] In any or all of the disclosed embodiments, the temperature control element includes an electronic cooling device.

[010] In any or all of the disclosed embodiments, the temperature control element comprises passages defined in the powder container for conducting a fluid through a body of the powder container.

[Oil] In any or all of the disclosed embodiments, the passages are part of a coolant circuit of a fluid cooling system configured to maintain the powder container within the selected temperature range.

[012] In any or all of the disclosed embodiments, the fluid cooling system is configured to maintain the powder container at or below 100° C.

[013] In any or all of the disclosed embodiments, the fluid cooling system is configured to maintain the powder container at a temperature below a sintering temperature of the powder. [014] In any or all of the disclosed embodiments, the powder container defines a volume configured to retain powder, and the passages of the powder container are offset from the volume along an axis extending in a direction of powder flow through the powder container.

[015] In any or all of the disclosed embodiments, the passages of the powder container are above the volume configured to retain powder.

[016] In any or all of the disclosed embodiments, the powder container comprises first and second side walls, and the passages are defined in the first and second side walls.

[017] In any or all of the disclosed embodiments, the first side wall defines a passage, the second side wall defines a passage, and the passage of the first side wall is in fluid communication with the passage of the second side wall.

[018] In any or all of the disclosed embodiments, the passage of the first side wall is in fluid communication with the passage of the second side wall by a conduit extending between the first side wall and the second side wall.

[019] In any or all of the disclosed embodiments, at least portions of the first and second side walls are angled toward each other in a direction of powder flow through the powder container.

[020] In any or all of the disclosed embodiments, the flow control assembly comprises a vibration generator.

[021] In any or all of the disclosed embodiments, the vibration generator is received within the body of the powder container.

[022] In any or all of the disclosed embodiments, the passages defined in the powder container are first passages, and the vibration generator is received in a second passage defined in the powder container.

[023] In any or all of the disclosed embodiments, the second passage is defined in a sloped portion of a side wall of the powder container.

[024] In any or all of the disclosed embodiments, the powder container comprises a plurality of second passages configured to receive a plurality of vibration generators. [025] In any or all of the disclosed embodiments, the powder container defines a plurality of openings through side walls of the powder container, the openings being in communication with the second passages to provide access to the vibration generators.

[026] In any or all of the disclosed embodiments, the vibration generator is offset from the passages for conducting fluid along a direction of powder flow through the powder container.

[027] In any or all of the disclosed embodiments, the flow control assembly further comprises a mesh screen positioned adjacent an opening of the powder container.

[028] In any or all of the disclosed embodiments, the powder container comprises a multipart assembly.

[029] In any or all of the disclosed embodiments, the powder container comprises a metal material.

[030] In any or all of the disclosed embodiments, the fluid is water, alcohol, a water-alcohol mixture, or oil.

[031] In any or all of the disclosed embodiments, the passages are part of a fluid circuit of a temperature control system operable to heat the powder container and cool the powder container by circulating a heat transfer fluid through the passages.

[032] In any or all of the disclosed embodiments, the temperature control system is configured to circulate the heat transfer fluid through the passages of the powder container to heat the powder container.

[033] In any or all of the disclosed embodiments, the temperature control system is configured to circulate the heat transfer fluid through the passages of the powder container to cool the powder container.

[034] In any or all of the disclosed embodiments, the temperature control system is configured to adjust a temperature of the heat transfer fluid circulating through the passages of the powder container to maintain the powder container within the selected temperature range. [035] In any or all of the disclosed embodiments, the selected temperature range is at or below 600° C, at or below 500° C, at or below 400° C, at or below 300° C, at or below 200° C, or at or below 100° C.

[036] In any or all of the disclosed embodiments, the heat transfer fluid comprises an aqueous liquid, oil, or a liquid organic compound.

[037] In another representative embodiment, an additive manufacturing system comprises the powder supply assembly of any embodiment described herein.

[038] In another representative embodiment, a method comprises producing a three- dimensional object with the additive manufacturing system of any embodiment described herein.

[039] In another representative embodiment, a method comprises controlling a temperature of a powder container of an additive manufacturing system to maintain the powder container within a specified temperature range, controlling a flow of powder from the powder container with a flow control assembly of the additive manufacturing system, and supplying the powder from the powder container toward a build platform of the additive manufacturing system on which an object is manufactured from powder.

[040] In any or all of the disclosed embodiments, the temperature of the powder container is maintained at a temperature below a sintering temperature of the powder.

[041] In any or all of the disclosed embodiments, the temperature of the powder container is maintained at a temperature higher than 100° C.

[042] In any or all of the disclosed embodiments, controlling the temperature of the powder container is performed by an electric heater, an electric cooling device, or any combination thereof.

[043] In any or all of the disclosed embodiments, controlling the temperature of the powder container includes circulating a fluid through passages defined in a body of the powder container. [044] In any or all of the disclosed embodiments, circulating the fluid further comprises circulating the fluid through the passages of the powder container to maintain the powder container at or below 100° C.

[045] In any or all of the disclosed embodiments, circulating the fluid further comprises circulating the fluid through the passages of the powder container to maintain the powder container below a sintering temperature of the powder.

[046] In any or all of the disclosed embodiments, maintaining the powder container within the specified temperature range comprises cooling the powder container, and a temperature of the fluid is 5° C to 25° C.

[047] In any or all of the disclosed embodiments, maintaining the powder container within the specified temperature range comprises heating the powder container, and a temperature of the fluid is 50° C to 400° C.

[048] In any or all of the disclosed embodiments, the fluid comprises an aqueous heat transfer fluid.

[049] In any or all of the disclosed embodiments, the fluid comprises water.

[050] In any or all of the disclosed embodiments, the fluid comprises oil or a liquid organic compound.

[051] In another representative embodiment, a powder supply assembly for an additive manufacturing system comprises a powder container configured to retain a powder, and a flow control assembly configured to control a flow of powder from the powder container, wherein the powder container includes fluid passages defined in a body of the powder container for conducting a heat transfer fluid through the powder container to control a temperature of the powder container.

[052] In another representative embodiment, a powder supply assembly for an additive manufacturing system comprises a powder container configured to retain a powder, and a flow control assembly configured to control a flow of powder from the powder container, wherein the powder container defines passages for conducting a fluid through a body of the powder container to maintain the powder container within a selected temperature range.

[053] In another representative embodiment, a method comprises circulating a fluid through passages defined in a body of a powder container of an additive manufacturing system to maintain the powder container within a specified temperature range, and controlling a flow of powder from the powder container with a flow control assembly of the additive manufacturing system.

[054] In another representative embodiment, an additive manufacturing system comprises a powder supply assembly comprising a powder container configured to retain a powder, and a flow control assembly configured to control a flow of powder from the powder container. The additive manufacturing system further comprises a build platform, and a suspension assembly configured to suspend the powder supply assembly over the build platform to distribute a powder onto the build platform, wherein the suspension assembly and the powder supply assembly are configured to resonate at a frequency of the flow control assembly.

[055] In another representative embodiment, a powder supply assembly for an additive manufacturing system comprises a powder container configured to retain a powder, and a flow control assembly configured to control a flow of powder from the powder container, wherein the powder container comprises a temperature control element.

[056] In another representative embodiment, an additive manufacturing system comprises a build platform, a powder supply assembly configured to distribute a powder onto the build platform, the powder supply assembly comprising a powder container, a suspension assembly configured to suspend the powder supply assembly over the build platform, and a flow control assembly comprising a vibration generator, wherein the suspension assembly and the powder supply assembly are configured to resonate at a frequency of the vibration generator.

[057] In another representative embodiment, an additive manufacturing system comprises a powder supply assembly comprising a powder container, the powder container configured to retain a powder, and a supply frame assembly configured to receive the powder container, wherein the powder container is secured to the supply frame assembly and movable relative to the supply frame assembly to agitate powder in the powder container.

[058] The foregoing and other objects, features, and advantages of the disclosed technology will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[059] FIG. 1A is a simplified side view of an implementation of a processing machine having features of the present embodiment.

[060] FIG. IB is a simplified top view of a portion of the processing machine of FIG. 1A.

[061] FIG. 2 is a simplified side view of another implementation of a processing machine having features of the present embodiment.

[062] FIG. 3 is a simplified side view of still another implementation of a processing machine having features of the present embodiment.

[063] FIG. 4 is a simplified top view of a powder bed assembly.

[064] FIG. 5 is a simplified top view of another implementation of a powder bed assembly.

[065] FIG. 6A is a perspective view of a portion of a powder bed assembly and a powder supply assembly.

[066] FIG. 6B is a cut-away view taken on line 6B-6B in FIG. 6A.

[067] FIG. 6C is a cut-away view of the powder supply assembly of FIG. 6B at a different time.

[068] FIG. 6D is a cut-away view taken from line 6D-6D in FIG. 6A.

[069] FIG. 6E is a simplified top view of the powder supply assembly without powder.

[070] FIG. 6F is a top view of a flow controller.

[071] FIG. 6G is a side view of another flow controller. [072] FIG. 7 is a perspective view of a powder container assembly including coolant passages and a supply frame assembly of a powder supply assembly for an additive manufacturing system, according to another embodiment.

[073] FIG. 8 is a perspective view of the powder container assembly of FIG. 7 received in the supply frame assembly.

[074] FIG. 9A is a top perspective view of the powder container assembly of FIG. 7.

[075] FIG. 9B is a cross-sectional front elevation view of the powder container assembly of FIG. 7 taken along line 9B-9B of FIG. 9A.

[076] FIG. 10 is a perspective view of the powder container assembly of FIG. 7 illustrating coolant passages defined in the powder container.

[077] FIG. 11 is a schematic cross-sectional view of the powder supply assembly of FIG. 7 illustrating fastener connections between the powder container and the supply frame assembly.

[078] FIG. 12 is a perspective view of another embodiment of a powder container assembly including coolant passages.

[079] FIG. 13 is a top, end-on perspective view of the powder container assembly of FIG. 12.

[080] FIG. 14 is a bottom perspective view of the powder container assembly of FIG. 12 and an associated flow control assembly.

[081] FIG. 15 is a magnified side elevation view of a portion of the powder container assembly of FIG. 12 illustrating vibration generators disposed in passages defined in the powder container.

[082] FIG. 16 is a magnified perspective view of a portion of the powder container assembly of FIG. 12 received in a supply frame assembly.

[083] FIG. 17 is a top, end-on perspective view of the powder container assembly of FIG. 12 including coolant fittings and conduits. [084] FIG. 18 is a perspective view of a part of the disassembled powder container assembly of FIG. 17.

[085] FIGS. 19A-19C are perspective views illustrating the flexible modes of a blade flexure, according to one embodiment.

[086] FIGS. 20A-20C are perspective views illustrating the directions or modes in which the blade flexure is relatively inflexible.

[087] FIG. 21 is a schematic diagram illustrating a mass suspended from a support by two blade flexures on one side.

[088] FIG. 22 is a schematic diagram illustrating a mass suspended from supports by two pairs of blade flexures.

[089] FIG. 23 is a perspective view of a lower surface of a powder supply assembly including a suspension system of blade flexures, according to one embodiment.

[090] FIG. 24 is a perspective view of a lower surface of a powder supply assembly including a suspension system of blade flexures, according to another embodiment.

[091] FIG. 25 illustrates straight and curved blade flexures.

[092] FIG. 26 is a graphical output of a finite element analysis model of a powder container and blade flexure suspension system.

[093] FIG. 27 is a schematic diagram illustrating a mass suspended from supports by blade flexures on opposite sides of the mass.

[094] FIG. 28 is a schematic diagram of another embodiment of a spring-mass system including journal bearings.

DETAILED DESCRIPTION

[095] The present disclosure pertains to additive manufacturing systems such as three- dimensional printing systems that are configured to create/build/print a solid object by depositing layers of powder onto the object, and fusing the powder to the object by application of heat. In certain embodiments, the powder material can comprise any of various metals or metal alloys (e.g., steel, aluminum, titanium, etc.). In certain embodiments, the heat source can be a high energy beam, such as an electron beam or other charged particle beam, which can be quickly and accurately directed over the surface of the object to fuse sequential layers of powder to the object. In certain embodiments, the systems described herein can be operated in a vacuum environment to facilitate generation of the electron beam. Thus, components of the system such as the powder supply assembly can be in thermal contact with the electron beam and/or other heat sources in the vacuum environment, and without the convective cooling of ambient air. Accordingly, certain embodiments described herein include temperature control elements such as fluid cooling systems including coolant circuits that extend through components of the powder supply assembly, such as the powder container. Such temperature control elements can maintain the temperature of the powder container, the powder, and/or components of the flow control assembly coupled to the powder container, such as vibration generators, within specified temperature ranges. Maintaining the powder container within a specified temperature range and/or controlling its temperature can include using such fluid circuits to heat the powder container.

[096] Moreover, powders used in additive manufacturing systems such as powders of the exemplary metals noted above can exhibit cohesive properties, causing the powders to clump together and inhibiting powder flow through the powder container. Accordingly, certain embodiments of the disclosure include suspension systems coupled to the powder container and tuned to resonate at an excitation frequency of a flow control assembly of the system. In certain embodiments, the flow control assembly can include one or more vibration generators, and the resonant frequency of the suspension and powder container can be tuned to the frequency of the vibration generators. In certain embodiments, the suspension system can comprise a plurality of blade flexures. In certain embodiments, the suspension assembly can be configured such that the powder container resonates/vibrates primarily along an axis aligned with the direction of powder flow through the powder container, and attenuates vibration in other modes/directions. In certain embodiments, components of the powder supply assembly such as the powder container can be coupled to stationary frame/support members of the system in such a way that the powder container vibrates/moves relative to the stationary support within a selected range of motion. In certain embodiments, the selected range of motion can be established by a difference in the diameter of fasteners coupling the powder container to the stationary frame and openings in the stationary frame though which the fasteners extend. This can allow the powder container to vibrate against the stationary frame, thereby agitating the powder in the powder container and improving powder flow. The features of any of the embodiments described herein can be combined in any combination to provide additive manufacturing systems with temperature control of the powder supply system components, and improved powder flow.

[097] Example 1: Additive Manufacturing S stem

[098] FIG. 1A is a simplified schematic side illustration of a processing machine 10 that may be used to manufacture one or more three-dimensional objects 11. As provided herein, the processing machine 10 can be an additive manufacturing system, e.g. a three-dimensional printer, in which a portion of the powder 12 (powder particles illustrated as small circles) in a series of powder layers 13 (illustrated as dashed horizontal lines) is joined, melted, solidified, and/or fused together to manufacture one or more three-dimensional object(s) 11. In FIG. 1A, the object 11 includes a plurality of small squares that represent the joining of the powder 12 to form the object 11.

[099] The type of three-dimensional object(s) 11 manufactured with the processing machine 10 may be almost any shape or geometry. As a non-exclusive example, the three-dimensional object 11 may be a metal part, or another type of part, for example, a resin (plastic) part or a ceramic part, etc. The three-dimensional object 11 may also be referred to as a “built part”.

[0100] The type of powder 12 joined and/or fused together may be varied to suit the desired properties of the object(s) 11. As a non-exclusive example, the powder 12 may include metal powder grains (e.g., including one or more of titanium, aluminum, vanadium, chromium, copper, stainless steel, or other suitable metals) or alloys for metal three-dimensional printing. Alternatively, the powder 12 may be non-metal powder, a plastic, polymer, glass, ceramic powder, organic powder, an inorganic powder, or any other material known to people skilled in the art. The powder 12 may also be referred to as “material” or “powder particles”.

[0101] A number of different designs of the processing machine 10 are provided herein. In certain implementations, the processing machine 10 includes (i) a powder bed assembly 14; (ii) a pre-heat device 16; (iii) a powder supply assembly 18 (illustrated as a box); (iii) a measurement device 20 (illustrated as a box); (iv) an energy system 22 (illustrated as a box); and (v) a control system 24 (illustrated as a box) that cooperate to make each three- dimensional object 11. The design of each of these components may be varied pursuant to the teachings provided herein. Further, the positions of the components of the processing machine 10 may be different than that illustrated in FIG. 1. Moreover, the processing machine 10 can include more components or fewer components than illustrated in FIG. 1A. For example, the processing machine 10 can include a cooling device (not shown in FIG. 1 A) that uses radiation, conduction, and/or convection to cool the powder 12. Alternatively, for example, the processing machine 10 can be designed without the pre-heat device 16 and/or the measurement device 20.

[0102] A number of different powder supply assemblies 18 are disclosed herein. As an overview, these powder supply assemblies 18 are uniquely designed to accurately, efficiently, evenly, and quickly distribute the powder layers 13 onto the powder bed assembly 14. Further, in certain implementations, the powder supply assembly 18 is centerless, and uniformly distributes a fine layer of the powder 12 over a large and broad powder bed assembly 14. This will improve the accuracy of the built object 11, and reduce the time required to form the built object 11.

[0103] The thickness of each powder layer 13 can be varied to suit the manufacturing requirements. In alternative, non-exclusive examples, one or more (e.g. all) of the powder layers 13 can have a uniform layer thickness (along the Z axis) of approximately twenty, thirty, forty, fifty, sixty, seventy, eighty, or ninety, or one hundred microns. However other layer thicknesses are possible. Particle sizes of the powder 12 can be varied. In one implementation, a common particle size is approximately fifty microns. Alternatively, in other non-exclusive examples, the particle size can be approximately twenty, thirty, forty, sixty, seventy, eighty, or ninety, or one hundred microns.

[0104] A number of figures include an orientation system that illustrates an X axis, a Y axis that is orthogonal to the X axis, and a Z axis that is orthogonal to the X and Y axes. It should be noted that any of these axes can also be referred to as the first, second, and/or third axes. Further, as used herein, movement with six degrees of freedom shall mean along and about the X, Y, and Z axes.

[0105] In FIG. 1A, a portion of the powder bed assembly 14 is illustrated in cut- away so that the powder 12, the powder layers 13 and the object 11 are visible. With the present design, one or more objects 11 can be simultaneously made with the processing machine 10. In FIG. 1A, only one object 11 is visible.

[0106] It should be noted that any of the processing machines 10 described herein may be operated in a controlled environment, e.g. such as a vacuum, using an environmental chamber 23 (illustrated in FIG. 1A as a box). For example, one or more of the components of the processing machine 10 can be positioned entirely or partly within the environmental chamber 23. Alternatively, at least a portion of one or more of the components of the processing machine 10 may be positioned outside the environmental chamber 23. Still alternatively, the processing machine 10 may be operated in non-vacuum environment such as inert gas (e.g., nitrogen gas or argon gas) environment.

[0107] FIG. IB is a simplified top view of a portion of the powder bed assembly 14 of FIG. 1A and the three-dimensional object 11. FIG. IB also illustrates (i) the pre-heat device 16 (illustrated as box) and a pre-heat zone 16A (illustrated with dashed lines) which represents the approximate area in which the powder 12 can be pre-heated with the pre-heat device 16; (ii) the powder supply assembly 18 (illustrated as a box) and a deposit zone 18A (illustrated in phantom) which represents the approximate area in which the powder 12 can be added and/or spread to the powder bed assembly 14 by the powder supply assembly 18; (iii) the measurement device 20 (illustrated as a box) and a measurement zone 20A (illustrated in phantom) which represents the approximate area in which the powder 12 and/or the object 11 can be measured by the measurement device 20; and (iv) the energy system 22 (illustrated as a box) and an energy zone 22A which represents the approximate area in which the powder 12 can be melted and fused together by the energy system 22.

[0108] It should be noted that these zones may be spaced apart different, oriented differently, or positioned differently from the non-exclusive example illustrated in FIG. IB. Additionally, the relative sizes of the zones 16A, 18 A, 20 A, 22 A may be different than what is illustrated in FIG. IB.

[0109] In FIGS. 1A and IB, in certain implementations, the processing machine 10 can be operated so that there is substantially constant relative motion along a moving direction 25 (illustrated by an arrow) between the object 11 being formed and one or more of the pre-heat device 16, the powder supply assembly 18, the measurement device 20, and the energy system 22. The moving direction 25 may include a rotation direction about a rotation axis 25 A. With this design, the powder 12 may be deposited and fused relatively quickly. This allows for the faster forming of the objects 11, increased throughput of the processing machine 10, and reduced cost for the objects 11.

[0110] In the implementation illustrated in FIG.1A and IB, the powder bed assembly 14 includes (i) a powder bed 26 that supports the powder 12 and the object 11 while being formed, and (ii) a device mover 28 (e.g. one or more actuators) that selectively moves the powder bed 26. In this implementation, the device mover 28 rotates the powder bed 26 about the rotation axis 25 A relative to the pre-heat device 16 (and the pre-heat zone 16A), the powder supply assembly 18 (and the deposit zone 18 A), the measurement device 20 (and the measurement zone 20A), and the energy system 22 (and the irradiation zone 22A). This allows nearly all of the rest of the components of the processing machine 10 to be fixed while the powder bed 26 is moved.

[0111] In the simplified schematic illustrated in FIG. 1A and IB, the powder bed 26 includes a build platform 26A and a support side wall 26B. In this embodiment, the build platform 26A is flat disk shaped and has a support surface, and the support side wall 26B is tubular shaped and extends upward from a perimeter of the support surface 26A. Alternatively, other shapes of the build platform 26A and the support side wall 26B may be utilized. In some implementations, the build platform 26A is moved somewhat similar to a piston relative to the support side wall 26B which act like as the piston’s cylinder wall. For example, a platform mover (not shown) can selectively move the build platform 26A downward as each subsequent powder layer 13 is added.

[0112] In another implementation, the build platform 26A is flat, rectangular shaped, and the support side wall assembly 26B are rectangular tube shaped and extends upward around the build platform 26A. Alternatively, other shapes of the build platform 26A and/or support side wall assembly 26B may be utilized. As non-exclusive examples, the build platform 26A can be polygonal-shaped, with the support side wall assembly 26B having the corresponding tubular-shape. In another implementation, the support side wall can be built concurrently as a custom shape around the object 11, while the object 11 is being built.

[0113] The device mover 28 can move the powder bed 26 at a substantially constant or variable angular velocity about the rotation axis 25 A. As alternative, non- exclusive examples, the device mover 28 may move the powder bed 26 at a substantially constant angular velocity of at least approximately 1, 2, 5, 10, 20, 30, 60, 100 or more revolutions per minute (RPM). Stated in a different fashion, the device mover 28 may move the powder bed 26 at a substantially constant angular velocity of between one and one hundred revolutions per minute. As used herein, the term “substantially constant angular velocity” shall mean a velocity that varies less than 10% over time. In one embodiment, the term “substantially constant angular velocity” shall mean a velocity that varies less 0.2% from the target velocity. The device mover 28 may also be referred to as a “drive device”.

[0114] Additionally or alternatively, the device mover 28 may move the powder bed 26 at a variable velocity or in a stepped or other fashion. For example, it may be desired to speed up or slow down the rotation of the powder bed 26 for some sections, either as part of a normal cycle like increase time under pre-heater, or as a smart corrective action during the build (e.g. to repair a defect). The rotation axis 25A may be aligned along with gravity direction, and may be along with an inclination direction about the gravity direction. [0115] In FIG. 1A, the device mover 28 includes a motor 28A (e.g., a rotary motor) and a device connector 28B (e.g., a rigid shaft) that fixedly connects the motor 28A to the powder bed 26. In other embodiments, the device connector 28B may include a transmission device such as at least one gear, belt, chain, or friction drive.

[0116] The powder 12 used to make the object 11 is deposited onto the powder bed 26 in a series of powder layers 13. Depending upon the design of the processing machine 10, the powder bed 26 with the powder 12 may be very heavy. With the present design, this large mass may be rotated at a constant or substantially constant speed to avoid accelerations and decelerations, and the required motion is a continuous rotation of a large mass, with no non- centripetal acceleration other than at the beginning and end of the entire exposure process. The melting process may be performed during the period when the motion is constant velocity motion.

[0117] The pre-heat device 16 selectively preheats the powder 12 in the pre-heat zone 16A that has been deposited on the powder bed 26 during a pre-heat time. In certain embodiments, the pre-heat device 16 heats the powder 12 to a desired preheated temperature in the pre-heat zone 16A when the powder 12 is moved through the pre-heat zone 16 A. The number of the pre-heat devices 16 may be one or plural.

[0118] In one embodiment, the pre-heat device 16 is positioned along a pre-heat axis (direction) 16B and is arranged between the measurement device 20 and the energy system 22. However, the pre-heat device 16 can be positioned at another location.

[0119] The design of the pre-heat device 16 and the desired preheated temperature may be varied. In one embodiment, the pre-heat device 16 may include one or more pre-heat energy source(s) 16C that direct one or more pre-heat beam(s) 16C at the powder 12. Each pre-heat beam 16D may be steered as necessary. As alternative, non-exclusives examples, each preheat energy source 16C may be an electron beam system, a mercury lamp, an infrared laser, a supply of heated air, thermal radiation system, a visual wavelength optical system or a microwave optical system. The desired preheated temperature may be 50% 75% 90% or 95% of the melting temperature of the powder material used in the printing. It is understood that different powders have different melting points and therefore different desired pre-heating points. As non-exclusive examples, the desired preheated temperature may be at least 300, 500, 700, 900, or 1000 degrees Celsius. Energy input may also vary dependent on melt duty of previous layers, specific regions on a layer, or progress though the build.

[0120] The powder supply assembly 18 deposits the powder 12 onto the powder bed 26. In certain embodiments, the powder supply assembly 18 supplies the powder 12 to the powder bed 26 in the deposit zone 18A while the powder bed 26 is being moved to form each powder layer 13 on the powder bed 26.

[0121] In one implementation, the powder supply assembly 18 extends along a powder supply axis (direction) 18B and is arranged between the measurement device 20 and the energy system 22. The powder supply assembly 18 can include one or more powder containers (not shown in FIGS. 1A and IB). The number of the powder supply assemblies 18 may be one or plural.

[0122] With the present design, the powder supply assembly 18 deposits the powder 12 onto the powder bed assembly 14 to sequentially form each powder layer 13. Once a portion of the powder layer 13 has been melted with the energy system 22, the powder supply assembly 18 evenly and uniformly deposits another (subsequent) powder layer 13.

[0123] It should be noted that the three-dimensional object 11 is formed through consecutive fusions of consecutively formed cross sections of powder 12 in one or more powder layers 13. For simplicity, the example of FIG. 1A illustrates only a few, separate, stacked powder layers 13. However, it should be noted that depending upon the design of the object 11, the building process will require numerous powder layers 13.

[0124] A number of alternative powder supply assemblies 18 are described in more detail below. In these embodiments, the powder supply assembly 18 is an overhead powder supply that supplies the powder 12 onto the top of the powder bed assembly 14.

[0125] The measurement device 20 inspects and monitors the melted (fused) layers of the object 11 as they are being built, and/or the deposition of the powder layers 13. The number of the measurement devices 20 may be one or plural. For example, the measurement device 20 can measure both before and after the powder 12 is distributed.

[0126] As non-exclusive examples, the measurement device 20 may include one or more optical elements such as a uniform illumination device, fringe illumination device (structured illumination device), cameras that function at one or more wavelengths, lens, interferometer, or photodetector, or a non-optical measurement device such as an ultrasonic, eddy current, or capacitive sensor.

[0127] In one implementation, the measurement device 20 is arranged between the powder supply assembly 18 and the pre-heat device 16, however, the measurement device 20 may be alternatively located.

[0128] The energy system 22 selectively heats and melts the powder 12 in the energy zone 22A to sequentially form each of the layers of the object 11 while the powder bed 26 and the object 11 are being moved. The energy system 22 can selectively melt the powder 12 at least based on a data regarding to the object 11 to be built. The data may be corresponding to a computer-aided design (CAD) model data. The number of the energy systems 22 may be one or plural.

[0129] In one embodiment, the energy system 22 is positioned along an energy axis (direction) 22B and is arranged between the pre-heat device 16 and the powder supply assembly 18. The design of the energy system 22 can be varied. In one embodiment, the energy system 22 may include one or more energy source(s) 22C (“irradiation systems”) that direct one or more irradiation (energy) beam(s) 22D at the powder 12. The one or more energy sources 22C can be controlled to steer the energy beam(s) 22D to melt the powder 12.

[0130] As alternative, non-exclusives examples, each of the energy sources 22C can be designed to include one or more of the following: (i) an electron beam generator that generates a charged particle electron beam; (ii) an irradiation system that generates an irradiation beam; (iii) an infrared laser that generates an infrared beam; (iv) a mercury lamp; (v) a thermal radiation system; (vi) a visual wavelength system; (vii) a microwave wavelength system; or (viii) an ion beam system. [0131] Different powders 12 have different melting points. As non-exclusive examples, the desired melting temperature may be at least 1000, 1400, 1700, 2000, or more degrees Celsius.

[0132] The control system 24 controls the components of the processing machine 10 to build the three-dimensional object 11 from the computer-aided design (CAD) model by successively melting portions of one or more of the powder layers 13. For example, the control system 24 can control (i) the powder bed assembly 14; (ii) the pre-heat device 16; (iii) the powder supply assembly 18; (iii) the measurement device 20; and (iv) the energy system 22. The control system 24 can be a distributed system.

[0133] The control system 24 may include, for example, a CPU (Central Processing Unit) 24A, a GPU (Graphics Processing Unit) 24B, and electronic memory 24C. The control system 24 functions as a device that controls the operation of the processing machine 10 by the CPU executing the computer program. This computer program is a computer program for causing the control system 24 (for example, a CPU) to perform an operation to be described later to be performed by the control system 24 (that is, to execute it). That is, this computer program is a computer program for making the control system 24 function so that the processing machine 10 will perform the operation to be described later. A computer program executed by the CPU may be recorded in a memory (that is, a recording medium) included in the control system 24, or an arbitrary storage medium built in the control system 24 or externally attachable to the control system 24, for example, a hard disk or a semiconductor memory. Alternatively, the CPU may download a computer program to be executed from a device external to the control system 24 via the network interface. Further, the control system 24 may not be disposed inside the processing machine 10, and may be arranged as a server or the like outside the processing machine 10, for example. In this case, the control system 24 and the processing machine 10 may be connected via a communication line such as a wired communications line (cable communications), a wireless communications line, or a network. In case of physically connecting with wired, it is possible to use serial connection or parallel connection of IEEE1394, RS-232x, RS- 422, RS-423, RS-485, USB, etc. or 10BASE-T, 100BASE-TX, 1000BASE- T or the like via a network. Further, when connecting using radio, radio waves such as IEEE 802. lx, OFDM, or the like, radio waves such as Bluetooth (registered trademark), infrared rays, optical communication, and the like may be used. In this case, the control system 24 and the processing machine 10 may be configured to be able to transmit and receive various types of information via a communication line or a network. Further, the control system 24 may be capable of transmitting information such as commands and control parameters to the processing machine 10 via the communication line and the network. The processing machine 10 may include a receiving device (receiver) that receives information such as commands and control parameters from the control system 24 via the communication line or the network. As a recording medium for recording the computer program executed by the CPU, a CD-ROM, a CD-R, a CD-RW, a flexible disk, an MO, a DVD-ROM, a DVD-RAM, a DVD-R, a DVD + R, a DVD-RW, a magnetic medium such as a magnetic disk and a magnetic tape such as DVD + RW and Blu-ray (registered trademark), a semiconductor memory such as an optical disk, a magneto- optical disk, a USB memory, or the like, and a medium capable of storing other programs. In addition to the program stored in the recording medium and distributed, the program includes a form distributed by downloading through a network line such as the Internet. Further, the recording medium includes a device capable of recording a program, for example, a general-purpose or dedicated device mounted in a state in which the program can be executed in the form of software, firmware or the like. Furthermore, each processing and function included in the program may be executed by program software that can be executed by a computer, or processing of each part may be executed by hardware such as a predetermined gate array (FPGA, ASIC) or program software, and a partial hardware module that realizes a part of hardware elements may be implemented in a mixed form.

[0134] It should also be noted that with the unique designs provided herein, multiple operations may be performed at the same time (simultaneously) to improve the throughput of the processing machine 10. Stated in another fashion, one or more of (i) pre-heating with the pre-heat device 16, (ii) measuring with the measurement device 20, (iii) depositing powder 12 with the powder supply assembly 18, and (iv) melting the powder with the energy system 22 may be partly or fully overlapping in time on different parts of the powder bed 26 to improve the throughput of the processing machine 10. For example, two, three, four, or all five of these functions may be partly or fully overlapping.

[0135] In certain implementations, the powder bed 26 may be moved down with the device mover 28 along the rotation axis 25A in a continuous rate via a fine pitch screw or some equivalent method. With this design, a height 29 between the most recent (top) powder layer 13 and the powder supply assembly 18 (and other components) may be maintained substantially constant for the entire process. Alternatively, the powder bed 26 may be moved down in a step down fashion at each rotation, which could lead to the possibility of a discontinuity at one radial position in the powder bed 26. As used herein, “substantially constant” shall mean the height 29 varies by less than a factor of three, since the typical thickness of each powder layer is less than one millimeter. In another embodiment, “substantially constant” shall mean the height 29 varies less than ten percent of the height 29 during the manufacturing process.

[0136] In this implementation, only the powder bed 26 is primarily moved, while everything else (pre-heat device 16, powder supply assembly 18, measurement device 20, energy system 22) are all fixed, making the overall system simpler. Also, the throughput of a rotary based powder bed 26 system is much higher since one or more steps can be performed in parallel rather than serially.

[0137] In the simplified example of FIG. 1A, the processing machine 10 additionally includes a component housing 30 that retains the pre-heat device 16, the powder depositor 18, the measurement device 20, and the energy system 22. Collectively these components may be referred to as the top assembly. Further, the processing machine 10 can include a housing mover 32 that can be controlled to selectively move the top assembly. The housing mover 32 and the device mover 28 may each include one or more actuators (e.g. linear or rotary). The housing mover 32 and/or the device mover 28 may be referred to as a first mover or a second mover.

[0138] It should be noted that processing machine 10 can be designed to have one or more of the following features: (i) one or more of the pre-heat device 16, the powder supply assembly 18, the measurement device 20, and the energy system 22 can be selectively moved relative to the component housing 30 and/or the powder bed 26 with one or more of the six degrees of freedom; (ii) the component housing 30 with one or more of the pre-heat device 16, the powder supply assembly 18, the measurement device 20, and the energy system 22 can be selectively moved relative to the powder bed 26 with one or more of the six degrees of freedom; and/or (iii) the powder bed 26 can be selectively moved relative to the component housing 30 with one or more of the six degrees of freedom.

[0139] In a specific, alternative implementation, the housing mover 32 can move the top assembly (or a portion thereof) upward (e.g. along and/or transverse to the rotation axis 25A) relative to the powder bed 26 at a continuous (or stepped) rate while the powder 12 is being deposited to maintain the desired height 29.

[0140] Additionally, or alternatively, the housing mover 32 can rotate the top assembly (or a portion thereof) relative to the powder bed 26 about the rotation axis 25A relative to the powder bed 26 during the printing of the object 11. In this implementation, the powder bed 26 can be stationary, rotated about the rotation axis in the clockwise direction, rotated about the rotation axis in the counterclockwise direction, and/or or moved linearly along and/or transverse to the rotation axis 25 A.

[0141] Stated in another fashion, the processing machine 10 illustrated in FIGS. 1A and IB may be designed so that (i) the powder bed 26 is rotated about the Z axis and moved along the rotation axis 25A; or (ii) the powder bed 26 is rotated about the rotation axis 25A, and the component housing 30 and the top assembly are moved along the rotation axis 25A only to maintain the desired height 29. In certain embodiments, it may make sense to assign movement along the rotation axis 25 A to one component and rotation about the rotation axis 25 A to the other.

[0142] FIG. 2 is a simplified side view of another embodiment of a processing machine 210 for making the object 211 with a portion of the powder bed assembly 214 illustrated in cutaway. In this embodiment, the three-dimensional printer 210 includes (i) a powder bed assembly 214; (ii) a pre-heat device 216 (illustrated as a box); (iii) a powder supply assembly 218 (illustrated as a box); (iv) a measurement device 220 (illustrated as a box); (v) an energy system 222 (illustrated as a box); (vi) an environmental chamber 223; and (vii) a control system 224 that are somewhat similar to the corresponding components described above. However, in this embodiment, the powder bed 226 of the powder bed assembly 214 can be stationary, and the housing mover 232 moves the component housing 230 with one or more of the pre-heat device 216, the powder supply assembly 218, the measurement device 220, and the energy system 222 relative to the powder bed 226.

[0143] As a non-exclusive example, the housing mover 232 may rotate the component housing 230 with the pre-heat device 216, the powder supply assembly 218, the measurement device 220, and the energy system 222 (collectively “top assembly”) at a constant or variable velocity about the rotation axis 225A. Additionally or alternatively, the housing mover 232 may move the top assembly along the rotation axis 225 A.

[0144] It should be noted that the processing machine 210 of FIG. 2 may be designed so that (i) the top assembly is rotated about the Z axis and moved along the Z axis to maintain the desired height 233 with the housing mover 232; or (ii) the top assembly is rotated about the Z axis, and the powder bed 226 is moved along the Z axis only with a device mover 228 to maintain the desired height 229. In certain embodiments, it may make sense to assign Z movement to one component and rotation to the other.

[0145] In this embodiment, the powder bed assembly 214 can be generally circular disk shaped or rectangular shaped.

[0146] FIG. 3 is a simplified side view of another embodiment of a processing machine 310 for making one or more object(s) 311 (two are illustrated) with a portion of the powder bed assembly 314 illustrated in cut-away. In this implementation, the three- dimensional printer 310 includes (i) a powder bed assembly 314; (ii) a pre-heat device 316 (illustrated as a box); (iii) a powder supply assembly 318 (illustrated as a box); (iv) a measurement device 320 (illustrated as a box); (v) an energy system 322 (illustrated as a box); (vi) an environmental chamber 323; and (vii) a control system 324 that are somewhat similar to the corresponding components described above. However, in this embodiment, the powder bed 326 includes a platform mover 326C in addition to the build platform 326A and the support side wall 326B. In this implementation, the build platform 326A can be moved linearly downward as each subsequent powder layer is added relative to the support side wall 326B with the platform mover 326C.

[0147] In alternative, non-exclusive implementations, the build platform 326A can have a build area 326D that is (i) flat, circular disk shaped for use with a corresponding support side wall 326B that is circular tube shaped; (ii) flat rectangular shaped for use with a corresponding support side wall 326B that is rectangular tube shaped, or (iii) polygonalshaped for use with a corresponding support side wall 326B that is polygonal tube shaped.

[0148] It should be noted that the processing machine 310 of FIG. 3 may be designed so that (i) one or more of the pre-heat device 316, the powder supply assembly 318, the measurement device 320, and the energy system 322 can be selectively moved relative to the component housing 330 and/or the powder bed 326 with one or more of the six degrees of freedom; (ii) the component housing 330 with one or more of the pre-heat device 316, the powder supply assembly 318, the measurement device 320, and the energy system 322 can be selectively moved relative to the powder bed 326 with one or more of the six degrees of freedom; and/or (iii) the powder bed 326 can be selectively moved relative to the component housing 330 with one or more of the six degrees of freedom.

[0149] FIG. 4 is a simplified top illustration of a powder bed assembly 414 that can be used in any of the processing machines 10, 210, 310 disclosed herein. In this embodiment, the powder bed assembly 414 can be used to make multiple objects 411 substantially simultaneously. The number of objects 411 that may be made concurrently can vary according the type of object 411 and the design of the processing machine 10, 210, 310. In FIG. 4, six objects 411 are made simultaneously. Alternatively, more than six or fewer than six objects 411 may be made simultaneously.

[0150] In FIG. 4, each of the objects 411 is the same design. Alternatively, for example, the processing machine 10, 210, 310 may be controlled so that one or more different types of objects 411 are made simultaneously. [0151] In FIG. 4, the powder bed assembly 414 includes a relatively large support platform 426A, and a plurality of separate, spaced apart, build assemblies 434 that are positioned on and supported by the support platform 426A. The number of separate build assemblies 434 can be varied. In FIG. 4, the powder bed assembly 414 includes six separate build assemblies 414, one for each object 411. With this design, a single object 411 is made in each build assembly 434. Alternatively, more than one object 411 may be built in each build assembly 434. Still alternatively, the powder bed assembly 414 can include more than six or fewer than six separate build assemblies 434.

[0152] In one, non-exclusive embodiment, the support platform 426A with the build assemblies 434 can be rotated like a turntable during printing of the objects 411 in a moving direction 425 about a support rotation axis 425A (illustrated with a “+”, e.g. the Z axis). With this design, each build assembly 434 is rotated about at least one axis 425A during the build process. Further, in this embodiment, the separate build assemblies 434 are spaced apart on the large common support platform 426A. The build assemblies 434 can be positioned on or embedded into the support platform 426A. As non-exclusive examples, the support platform 426A can be disk shaped or rectangular shaped.

[0153] As provided herein, each of the build assemblies 434 defines a separate, discrete build region. For example, each build assembly 434 can include a build platform 434A, and a sidewall assembly 434B. In one embodiment, each build assembly 434 is an open container in which the object 411 can be built. In this design, after the object 411 is printed, the build assembly 434 with the printed object 411 can be removed from the support platform 426A via a robotic arm (not shown in FIG. 4) and replaced with an empty build assembly 434 for subsequent fabrication of the next object 411.

[0154] As non-exclusive examples, each build platform 434A can define a build area 434C that is rectangular, circular, or polygonal shaped.

[0155] In an alternative embodiment, one or more of the build platforms 434A can be moved somewhat like an elevator vertically (along the Z axis) relative to its side wall assembly 434B with a platform mover assembly 434D (illustrated in phantom with a box) during fabrication of the objects 411. Each platform mover assembly 434D can include one or more actuators. Fabrication can begin with the build platform 434A placed near the top of the side wall assembly 434B. The powder supply assembly (not shown in FIG. 4) deposits a thin layer of powder into each build assembly 434 as it is moved (e.g. rotated) below the powder supply assembly. At an appropriate time, the build platform 434A in each build assembly 434 is stepped down by one layer thickness so the next layer of powder may be distributed properly.

[0156] In some embodiments, one or more platform mover assemblies 434D can also or alternatively be used to move (e.g. rotate) one or more of the build assemblies 434 relative to the support platform 426A and each other in a platform direction 434E about a platform rotation axis 434F (illustrated with a “+”, e.g. the Z axis). With this design, each build platform 434A can be rotated about two, separate, spaced apart and parallel axes 425A, 434F during the build process.

[0157] In one, non-exclusive example, the support platform 426A can be rotated (e.g., at a substantially constant rate) in the moving direction 425 (e.g. counterclockwise), and one or more of the build assemblies 434 can be moved (e.g. rotated) relative to the support platform 426A in the opposite direction 434E (e.g. clockwise) during the printing process. In this example, the rotational speed of the support platform 426A about the support rotational axis 425A can be approximately the same or different from the rotational speed of each build assembly 434 relative to the support platform 426A about the platform rotational axis 434F.

[0158] Alternatively, the support platform 426A can be rotated (e.g., at a substantially constant rate) in the moving direction 425 (e.g. counterclockwise), and one or more of the build assemblies 434 can be moved (e.g. rotated) relative to the support platform 426A in the same direction 434E (e.g. counterclockwise) during the printing process.

[0159] FIG. 5 is a simplified top illustration of another implementation of a powder bed assembly 514 that can be used in any of the processing machines 10, 210, 310 disclosed herein. In this implementation, the powder bed assembly 514 can be used to make multiple objects (not shown in FIG. 5) substantially simultaneously. [0160] In FIG. 5, the powder bed assembly 514 includes a relatively large support platform 526A, and a plurality of separate, spaced apart, build assemblies 534 that are integrated into the support platform 526A. The number of separate build assemblies 534 can be varied. In FIG. 5, the powder bed assembly 514 includes four separate build assemblies 534. With this design, one or more objects can be made on each build assembly 534. Alternatively, the powder bed assembly 514 can include more than four or fewer than four separate build assemblies 534.

[0161] In FIG. 5, each build assembly 534 defines a separate build platform 534A that is selectively lowered like an elevator with a platform mover assembly 534D (illustrated in phantom with a box) into the support platform 526 A during the manufacturing process. With this design, the support platform 526A can define the support side wall for each build platform 534A. Fabrication can begin with the build platform 534A placed near the top of the support platform 526A. The powder supply assembly (not shown in FIG. 5) deposits a thin layer of powder onto each build platform 534 A as it is moved (e.g. rotated) below the powder supply assembly. At an appropriate time, each build platform 534A is stepped down by one layer thickness so the next layer of powder may be distributed properly. Alternatively, each build platform 534A can be moved in steps that are smaller than the powder layer or moved in a continuous fashion, rather than in discrete steps.

[0162] In this FIG., each build platform 534A defines a circular shaped build area 534C that receives the powder (not shown in FIG. 5). Alternatively, for example, each build area 534C can have a different configuration, e.g. rectangular or polygonal shaped.

[0163] Additionally, the support platform 526A can be annular shaped and powder bed 526 can include a central, support hub 526D. In this implementation, there can be relative movement (e.g. rotation) between the support platform 526A and the support hub 526D. As a result thereof, one or more of the other components (e.g. the powder supply assembly) of the processing machine (not shown in FIG. 5) can be coupled to the support hub 526D.

[0164] In one, non-exclusive embodiment, the support platform 526A with the build assemblies 534 can be rotated like a turntable during printing of the objects in a moving direction 525 about the support rotation axis 525A (illustrated with a “+”) relative to the support hub 526D. With this design, each build platform 534A is rotated about at least one axis 525 A during the build process.

[0165] In some embodiments, one or more platform mover assemblies 534D can be used to move (e.g. rotate) one or more of the build assemblies 534 relative to the support platform 526A and each other in a platform direction 534E about a platform rotational axis 534F (illustrated with a “+”, e.g. along the Z axis). With this design, each build platform 534A can be rotated about two, separate, spaced apart and parallel axes 525A, 534F during the build process.

[0166] In one, non-exclusive example, the support platform 526A can be rotated (e.g., at a substantially constant rate) in the moving direction 525 (e.g. counterclockwise), and one or more of the build assemblies 534 can be moved (e.g. rotated) relative to the support platform 526A in the opposite, platform direction 534E (e.g. clockwise) during the printing process. In this example, the rotational speed of the support platform 526A about the support rotational axis 525A can be approximately the same or different from the rotational speed of each build assembly 534 relative to the support platform 526A about the platform rotational axis 434F.

[0167] Alternatively, the support platform 526A and one or more of the build assemblies 534 can be rotated in the same rotational direction during the three-dimensional printing operation.

[0168] It should be noted that in FIGS. 4 and 5, a separate platform mover assembly 434D, 534D is used for each build assembly 434, 534. Alternatively, one or more of the platform mover assemblies 434D, 534D can be designed to concurrently move more than one build assembly 434,534.

[0169] FIG. 6A is a perspective view of a portion of a powder bed assembly 614 including at least one build platform 634A, and a powder supply assembly 618 that can be integrated into in any of the processing machines 10, 210, 310 described above. For example, the powder bed assembly 614 and the powder supply assembly 618 can be designed to have one or more the following movement characteristics while powder 612 is being deposited on the build platform 634A: (i) the build platform 634A is stationary; (ii) the build platform 634A is moved relative to the powder supply assembly 618; (iii) the build platform 634A is moved linearly (along one or more axes) relative to the powder supply assembly 618; (iv) the build platform 634A is rotated (about one or more axes) relative to the powder supply assembly 618; (v) the powder supply assembly 618 is stationary; (vi) the powder supply assembly 618 is moved relative to the build platform 634A; (vii) the powder supply assembly 618 is moved linearly (along one or more axes) relative to the build platform 634A; and/or (viii) the powder supply assembly 618 is rotated (about one or more axes) relative to the build platform 634 A. These can be collectively referred to as “Movement Characteristics (i)-(viii)”.

[0170] It should be noted that the powder bed assembly 614 and the powder supply assembly 618 can be designed to have any combination of the Movement Characteristics (i)-(viii). For example, the powder bed assembly 614 and the powder supply assembly 618 can be designed to have one, two, three, four, five, six, seven, or all eight of the Movement Characteristics (i)- (viii). Further, the build platform 634 A can be circular, rectangular or other suitable shape.

[0171] In the implementation illustrated in FIG. 6A, the powder bed assembly 614 is somewhat similar to the implementation illustrated in FIG. 5, and includes a relatively large support platform 626A, a central support hub 626D, and a plurality of separate, spaced apart, build assemblies 634 (only one is illustrated) that are integrated into the support platform 626A. With this design, the support platform 626A with the build assemblies 634 can rotate relative to the support hub 626D, and/or the build assemblies 634 can rotate relative to the support platform 626A.

[0172] Further, in FIG. 6A, the powder supply assembly 618 is secured to the support hub 626D, and cantilevers and extends radially over the support platform 626A to selectively deposit the powder 612 (illustrated with small circles) onto the moving build assemblies 634. Alternatively, or additionally, the powder supply assembly 618 could be designed to be moved (e.g. linearly or rotationally) relative to the build assemblies 634. Still alternatively, the powder supply assembly 618 can be retained in another fashion than via the support hub 626D. For example, the powder supply assembly 618 can be coupled to the upper component housing 30 illustrated in FIG. 1A. [0173] FIG. 6B is a cut-away view of the powder supply assembly 618 taken on line 6B-6B in FIG. 6A.

[0174] With reference to FIGS. 6A and 6B, the powder supply assembly 618 is a top-down, gravity driven system that is shown with a circular shaped build platform 634A. In one implementation, the powder supply assembly 618 includes a supply frame assembly 638, a powder container assembly 640, and a flow control assembly 642 that is controlled by the control system 624 to selectively and accurately deposit the powder 612 onto the build platform(s) 634A. The design of each of these components can be varied to suit the design requirements of processing machine 10, 210, 310. In FIGS. 6A and 6B, the flow control assembly 642 is illustrated as being recently activated and the powder supply assembly 618 is releasing the powder 612 towards the build platform 634 A.

[0175] The supply frame assembly 638 supports and couples the powder container assembly 640 and the flow control assembly 642 to the rest of the processing machine 10, 210, 310. The supply frame assembly 638 can fixedly couple these components to the support hub 626D. In one, non-exclusive implementation, the supply frame assembly 638 includes (i) a riser frame 638 A that is fixedly coupled to and extends upwardly along the Z axis from the support hub 626D; and (ii) a transverse frame 638B that is fixedly coupled to and cantilevers radially away from the riser frame 638 A. It should be noted that either the riser frame 638 A, and the transverse frame 638B can be referred to as a first frame or a second frame.

[0176] The riser frame 638 A is rigid and includes (i) a riser proximal end 638C that is secured to the support hub 626D, and (ii) a riser distal end 638D that is positioned above the support hub 626D. Further, the transverse frame 638B is rigid and includes (i) a transverse proximal end 638E that is secured to the riser distal end 638D, and (ii) a transverse distal end 638F that extends over an outer perimeter of the build platform 634 A. In one, non-exclusive implementation, the riser frame 638 A is right cylindrical shaped (e.g. hollow or solid), and the transverse frame 638 A is rectangular beam shaped. However, other shapes and configurations can be utilized. [0177] Additionally, the transverse frame 638B can include a frame passageway 638G that allows the powder 612 from the flow control assembly 642 to flow therethrough. For example, the frame passageway 638G can be rectangular shaped. Further, the frame passageway 638G can define the supply outlet 639 of the powder 612 from the powder supply assembly 618. The supply outlet 639 is in fluid communication with the powder container assembly 640 and the flow control assembly 642.

[0178] In one embodiment, the supply outlet 639 is positioned above and spaced apart a separation distance 643 from the build platform(s) 634A or uppermost powder layer on the build platform 634A (e.g., facing the build platform). The size of the separation distance 643 can vary depending on the environment around the powder supply assembly 618. For example, the separation distance 643 can be larger if operated in a vacuum environment. As a non-exclusive embodiment, the separation distance 643 can be as small as the largest powder particle size. As a non-exclusive example, the separation distance 643 can be between approximately zero to fifty millimeters.

[0179] Alternatively, the powder supply assembly 618 can be designed so that the supply outlet 639 is directly adjacent to and/or against the build platform(s) 634A or uppermost powder layer on the build platform 634A.

[0180] The powder container assembly 640 retains the powder 612 prior to being deposited onto the build platform(s) 634A. The powder container assembly 640 can be positioned above and coupled to the transverse frame 638B of the supply frame assembly 638. In one nonexclusive implementation, the powder container assembly 640 is open at the top and the bottom, and can include a powder container 640 A that retains the powder 612, and a container base 640B that couples the powder container 640A to the transverse frame 638B with the flow control assembly 642 positioned therebetween. For example, the powder container 640A and the container base 640B can be integrally formed or secured together during assembly. In this implementation, the opening at the top of the powder container assembly 640 is larger than the opening at its bottom. [0181] The size and shape of the powder container 640A can be varied to suit the powder 612 supply requirements for the system. In one non-exclusive implementation, the powder container 640A is tapered, rectangular tube shaped (V shaped cross- section) and includes (i) a bottom, container proximal end 640C that is coupled to the container base 640B, and that is an open, rectangular shape; (ii) a top, container distal end 640D that is an open, rectangular tube shaped and positioned above the proximal end 640C; (iii) a front side 640E; (iv) a back side 640F; (v) a left side 640G; and (vi) a right side 640H. Any of these sides can be referred to as a first, second, third, etc side. The powder container 640A can function as a funnel that uses gravity to urge the powder 612 against the flow control assembly 642.

[0182] In one design, the left side 640G and the right side 640H extend substantially parallel to each other; while the front side 640E and a back side 640F taper towards each other moving from the container distal end 640D to the container proximal end 640C. The sides 640E, 640F can be steep (near vertical). As non-exclusive examples, the angle of taper relative to normal (vertical) can be at approximately 0, 0.5, 1, 2, 4, 6, 8, 10, 20, 30 degrees or other angles. The angle of taper can be determined based upon the characteristics (e.g. size) of the powder particles, the material of the powder particles, the amount of powder to be retained in the powder container 640A and other factors. In certain implementations, the powder container 640A comprises two slopes (walls 640E, 640F) getting closer to each other from one end (top 640D) to the other end (bottom 640C) on which the flow controller 642A is provided, and the at least one vibration generator 642C is provided on the at least one wall 640E, 640F. Stated in another fashion, the powder container 640A comprises two walls 640E, 640F that slope towards each other from a first end 640D to the second end 640C in which the flow controller 642A is located. An angle between two slopes of the walls 640E, 640F can be determined based upon a type of powder 612. As provided herein, the plurality of vibration generators 642C are provided at the both of two walls 640E, 640F. Further, in certain implementations, the flow controller 642A is elongated a first direction (e.g. along the Y axis) that crosses the build platform 634A, and the plurality of vibration generators 642C are provided at the both of two walls 640E, 640F along the first direction. [0183] The container base 640B can be rectangular tube shaped to allow the powder 612 to flow therethrough.

[0184] It should be noted that other shapes and configurations of the powder container 640 A can be utilized. For example, the powder container 640A can have a tapering, oval tube shape, or another suitable shape.

[0185] The control system 424 controls the flow control assembly 642 to selectively and accurately control the flow of the powder 612 from the supply outlet 639 onto the build platform(s) 634A. In one implementation, the flow control assembly 642 includes a flow controller 642A and an activation system 642B. In this implementation, (i) the flow controller 642A can be a flow restrictor such as one or more mesh screen(s) or other porous structure; and (ii) the activation system 642B can include one or more vibration generators 642C that are controlled by the control system 624 to selectively vibrate the powder container 640A. Each vibration generator 642C can be a vibration motor.

[0186] With this design, sufficient vibration of the powder container 640A by the vibration generator(s) 642C causes the powder 612 to flow through the flow controller 642A to the build platform(s) 634A. In contrast, if there is insufficient vibration of the powder container 640A by the vibration generator(s) 642C, there is no flow through the flow controller 642A. Stated in another fashion, the rate (amplitude and frequency) of vibration by the vibration generator(s) 642C can control the flow rate of the powder 612 through the flow controller 642A to the build platform(s) 634A. Generally speaking, no vibration results in no flow of the powder 612, while the flow rate of the powder 612 increases as vibration rate increases. Thus, the vibration generator(s) 642C can be controlled to precisely control the flow rate of powder 612 to the build platform(s) 634A.

[0187] The location of the flow controller 642A can be varied. In FIGS. 6A and 6B, the flow controller 642A is located between the powder container 640A and the transverse frame 638B. Alternatively, for example, the flow controller 642A can be located below the transverse frame 638B near the supply outlet 639. [0188] The number and location of the vibration generator(s) 642C can be varied. In the non-exclusive implementation in FIGS. 6A and 6B, the activation system 642B includes (i) five spaced apart vibration generators 642C that are secured to the front side 640E near the top, container distal end 640D; and (ii) five spaced apart vibration generators 642C (only one is visible in FIG. 6B) that are secured to the back side 640F near the container distal end 640D. These vibration generators 642C are located above the flow controller 642A to vibrate the powder 612 in the powder container 640A. Alternatively, the activation system 642B can include more than ten or fewer than ten vibration generators 642C, and/or one or more of the vibration generators 642C located at different positions than illustrated in FIGS. 6 A and 6B.

[0189] The five vibration generators 642C on each side 640E, 640F can be spaced apart linearly moving left to right. In FIG. 6A, the individual vibration generators 642C on the front side 640E are labeled A-E moving left to right linearly for ease of discussion. With this design, the vibration generators 642C can be independently controlled to control the distribution rate of the powder 612 moving linearly along the power supply assembly 618. This allows for control of the powder distribution radially from near the center to near the edge of the powder bed assembly 614. For example, if more powder 612 is needed near the edge than the center, the vibration generators 642C labelled “D” and “E” can be activated more than the vibration generators 642C labelled “A” and “B”.

[0190] With the present design, when it is desired to deposit the powder 612 onto the build platform 634A, the vibration generator(s) is(are) 642C turned ON to start the vibration motion. At this time, the powder 612 will pass from the powder container 640A through the flow controller 642A to deposit the powder 612. In contrast, when it is desired to stop the deposit of the powder 612, the vibration generators 642C are OFF, and the powder 612 will remain inside the powder container 640A.

[0191] With the present design, a thin, accurate, even layer of powder 612 can be supplied to the build platform(s) 634A without having to spread the powder 612 (e.g. with a rake) using the top-down vibration activated, powder supply assembly 618 disclosed herein. This powder supply assembly 618 is cost-effective, simple, and reliable method for delivering powder 612. Further, it requires a minimal amount of hardware to achieve even powder layers 612 on the build platform(s) 634A.

[0192] In certain embodiments, the flow controller 642A can be grounded to reduce static charges of the metal powder 612.

[0193] Additionally, or alternatively, the powder supply assembly 618 can include one or more heating and/or cooling devices/systems referred to herein as temperature control elements. Representative temperature control elements are indicated at 645A-645D on the inner or outer surface of powder container 640, on the transverse frame 638B, and/or near the separation distance 643. The temperature control elements can comprise, for example, any of a variety of electronic heating and/or cooling devices such as thermoelectric heat pumps (e.g., Peltier devices, thermoelectric coolers (TECs), etc.), preheaters/heaters, fluid cooling systems or portions thereof, and/or combinations of any of the above. For example, in certain embodiments one or more of the temperature control elements can comprise an electronic cooling device such as a TEC device in combination with a preheater. In certain embodiments, different types of temperature control elements can be provided at different locations on the powder supply assembly 618, such as preheaters and/or TEC devices on the surfaces and outlet of the powder container 640, and a fluid cooling system (e.g., including coolant passages) coupled to or extending through the body of the powder container as described in greater detail below.

[0194] The non-exclusive implementation illustrated in FIG. 6B includes (i) one or more temperature control elements (e.g., preheaters) 645A that are positioned near the inner surface of the powder container 640; (ii) one or more temperature control elements (e.g., preheaters) 645B that are positioned near the outer surface of the powder container 640; (iii) one or more temperature control elements (e.g., preheaters) 645C that are positioned on the transverse frame 638B; and (iv) one or more temperature control elements (e.g., preheaters) 645D that are positioned on the transverse frame 638B near the supply outlet 639. With this design, the temperature control elements 645A-645D can be controlled to control the temperature (e.g., preheat) the powder 612 before, during, and/or after passing through the flow controller 642A. Stated in another fashion, the powder container temperature control elements 645A-645D (different from the build pre-heater) can be located around the body of the powder container 640, or possibly, within the container 640. Another option might be an “on-demand” variant that either separately, or in addition to a bulk container 640 temperature control element or heater, locally pre-heats the powder further somewhere near the dispensing process.

[0195] Additionally, or alternatively, the powder supply assembly 618 can be used with a powder recoater (not shown) such as a rake, roller, wiper, squeegee, and/or a brush to further improve the flat powder surface.

[0196] FIG. 6C is a cut-away view of the powder supply assembly 618 similar to FIG. 6B, except in FIG. 6C, the vibration generators 642C are turned off. At this time, no powder 612 is flowing through the flow controller 642A.

[0197] FIG. 6D is a cut-away view taken from line 6D-6D in FIG. 6A, without the powder. Basically, FIG. 6D illustrates the powder supply assembly 618, including a portion of the supply frame assembly 638, the powder container assembly 640, and the flow control assembly 642.

[0198] FIG. 6E is a simplified top view of the powder supply assembly 618, without the powder. FIG. 6D illustrates the powder supply assembly 618, including the powder container assembly 640, and the flow controller 642 A and the vibration generators 642C of the flow control assembly 642.

[0199] FIG. 6F is a top view of one implementation of the flow controller 642A. In this implementation, the flow controller 642A includes a flow structure 642D, and a plurality of flow apertures 642E that extend through the flow structure 642D. In this embodiment, the flow structure 642D is rectangular plate shaped to correspond to the bottom container end 640C (illustrated in FIG. 6B). However, other shapes are possible. For example, the flow structure 642D can be shaped the same as the build platform 634A (illustrated in FIG. 6A) to allow fast and efficient supply of powder to the build platform 634A.

[0200] The flow apertures 642E can have a circular, oval, square, polygonal, or other suitable shape. Further, flow apertures 642E can follow a straight or curved path through the flow structure 642D. Moreover, in this implementation, one or more (typically all) of the flow apertures 642E have an aperture size that is larger than a nominal powder particle size of each of the powder particles 612. In alternative, non- exclusive examples, the aperture size is at least approximately 1, 1.25, 1.5, 1.7, 2, 2.5, 3 or 4 times the nominal powder particle size. Further, in alternative, non-exclusive examples, the aperture size is less than approximately 5, 6, 7, 8 or 10 times the nominal powder particle size. Stated in a different fashion, one or more (typically all) of the flow apertures 642E have an aperture cross-sectional area that is larger than a nominal powder particle cross sectional area of the individual particles of powder 612 (illustrated in FIG. 6A). In alternative, non-exclusive examples, one or more (typically all) of the flow apertures 642E have an aperture cross-sectional area is equal to or larger than the nominal powder cross sectional area of the individual particles of powder 612 by at least, but not limited to, 1, 2, 3, 5, 10, 20, 40, 50, 60, 70, 80, 90, 100, 150, or 200 percent. Stated differently, as non-exclusive examples, the aperture cross- sectional area can be at least approximately ten, twenty, fifty, one hundred, or one thousand times the nominal powder cross-sectional area. Stated in yet another fashion, one or more (typically all) of the flow apertures 642E have an aperture diameter that is larger than a nominal powder particle diameter of the powder particles 612. In alternative, non-exclusive examples, the aperture diameter is at least approximately 1, 1.25, 1.5, 1.75, 2, 3 or 4 times the nominal powder particle diameter. Further, in alternative, non-exclusive examples, the aperture diameter is less than approximately 5, 6, 7, 8 or 10 times the nominal powder particle diameter.

However, depending upon the design, other aperture sizes, diameters or cross-sectional areas are possible.

[0201] FIG. 6G is a side view the flow structure 642D of the flow controller 642A. In this implementation, the flow structure 642D includes one or more mesh screens 642F. In FIG. 6G, the flow structure 642D includes four mesh screens 642F. Alternatively, it can include more than four or fewer than four mesh screens 642F. In this design, the mesh screens 642F combine to define the plurality of spaced apart flow apertures 642E (illustrated in FIG. 6F).

[0202] With reference to FIGS. 6A-6G, in certain implementations, the sizes of flow apertures 642E, the vibration amplitude and/or the vibration directionality of the vibration generator(s) 642C may be adjusted to control the amount of the powder 612 supplied over the build platform 634A. The control system 624 may control the vibration generators 642C based on feedback results from the measurement device 20 (illustrated in FIG. 1A). For example, the measurement device 20 measures (monitors) the condition of the build platform(s) 634A (e.g., the topography of the powder layer, the irregularity of the surface of the powder layer, the geometry of the as-built object 11, the powder quality, the powder temperature, etc.) and the control system 624 controls the vibration generator(s) 642C so as to individually adjust the amount and location of powder 612 deposited on the build platform(s) 634A. Optionally, the flow controller 642A can include a shutter assembly for limiting and controlling a powder deposition area on the build platform 634A. The shutter assembly can be provided at or near the supply outlet 639, and controlled by the control system 624 along with the vibration generator(s) 642C. The powder supply assembly 618 is designed to supply arbitrary amounts of the powder 612 in every area including individual sub-areas (along the radial direction perpendicular to the z-axis) of each build platform 634A. Additional details regarding the three-dimensional printing systems described herein can be found in PCT International Application Publication No. WO2021003271, which is incorporated herein by reference.

[0203] Example 2: Powder Suppl Assembly with Fluid Cooling System

[0204] FIGS. 7 and 8 illustrate another embodiment of a powder supply assembly 700 including a powder container assembly 702, a supply frame assembly 704, and a flow control assembly generally indicated at 706. FIG. 7 illustrates the powder container assembly 702 and the supply frame assembly 704 in a spaced apart relationship, and FIG. 8 illustrates the powder container assembly received by the supply frame assembly.

[0205] Referring to FIG. 7, the powder container assembly 702 can comprise a powder container 703. The powder container 703 can comprise a first end portion 708 and a second end portion 710. The powder container 703 can comprise a first end wall 712 at the first end portion 708, and a second end wall 714 at the second end portion 710. First and second side walls 716 and 718 can extend between the end walls 712 and 714. In the illustrated embodiment, portions of the side walls 716 and 718 can be angled toward each other or inclined in a direction of powder flow through the powder container (e.g., along the z-axis). Thus, the powder container 703 can define a U-shaped or V-shaped interior powder storage volume 760 as described above, and as best shown in FIG. 11. Still referring to FIG. 11, the end walls 712, 714 and the angled portions of the side walls 716, 718 can define an opening/outlet/slot 715 extending along the lower portion of the powder container 703 through which powder can flow out of the powder container. A flow restrictor such as a mesh screen can be positioned beneath the slot 715 of the powder container 703, as described above.

[0206] In certain embodiments, the powder container 703 can comprise a multi-part assembly including separable members or halves 720 and 722. In certain embodiments, the first member 720 can comprise the first side wall 716, a portion of the end wall 712 and a portion of the end wall 714. The second member 722 can comprise the second side wall 718, a portion of the end wall 712, and a portion of the end wall 714. In the illustrated embodiment, the end walls 712 and 714 can comprise respective spacer members 724 and 726 positioned between the members 720 and 722 to increase the length of the end walls 712 and 714, although in other embodiments the end walls 712 and 714 can be formed entirely by the members 720 and 722, and can have any specified length. In certain embodiments, any or all of the various members 720, 722, 724, and/or 726 can be coupled together by fastener such as bolts, screws, or other fastening means.

[0207] In certain embodiments, the flow control assembly 706 can comprise a plurality of agitators or vibration generators, as described above. In the illustrated embodiment, the powder container 703 can define a plurality of passages/bores/tubes/slots/channels 728 configured to receive the vibration generators, which can be configured as vibrator motors in certain embodiments. In the illustrated configuration, the powder container 703 can comprise six passages 728 (also referred to as second passages), with three passages 728 defined in the first side wall 716 and three passages defined in the second side wall 718. In the illustrated embodiment the passages 728 are defined in the angled portions of the side walls 716 and 718 adjacent the powder storage volume 760, although the passages may be formed elsewhere in the structure. In certain embodiments, the side walls 716 and 718 can define openings, slots, etc., in the exterior of the walls that are in communication with the passages 728 to provide access to the passages 728 for, for example, electrical connections to the vibration generators, attachment members/means for securing the vibration generators to the powder container, etc.

[0208] In certain embodiments, it can be advantageous to cool the powder container assembly 702 and/or the flow control assembly 706, such as by circulating a liquid or gaseous coolant through passages defined in the powder container 703. Thus, in certain embodiments the powder supply assembly can include a temperature control element in the form of a fluid cooling system generally indicated at 729. The fluid cooling system 729 can comprise any of a variety of elements, including but not limited to a coolant reservoir, pump(s), coolant lines/conduits, heat exchanger(s), etc. Any or all of the components of the fluid cooling system can be located in the environmental chamber, or outside the environmental chamber, depending upon the particular requirements of the system.

[0209] For example, in the illustrated embodiment the powder container assembly 702 can comprise a coolant circuit generally indicated at 730, which can be a part of the fluid cooling system 729. Referring to FIGS. 7-10, the first side wall 716 of the powder container 703 can comprise a member or portion 732 positioned above and extending from/coupled to the angled portion of the first side wall. The second side wall 718 can comprise a portion 734 positioned above and extending from/coupled to the angled portion of the second side wall 718. Stated differently, the portions 732 and 734 can be offset from the powder-containing volume 760 along the z-axis (FIG. 7), which can extend in the direction of powder flow through the powder container 703 (e.g., powder can flow through the container in a direction along the negative z-axis in FIG. 7) such that the coolant passages are higher than the volume 760. The portions 732 and 724 can be integrally formed with the respective halves 720 and 722 of the powder container, or separately formed and coupled to the powder container according to the particular requirements of the system. As used herein, “integrally formed” refers to a construction that does not require any welds, fasteners or other coupling means for securing two features together.

[0210] Referring to FIG. 10, the portion 732 can define a coolant passage 736 extending along the length of the portion 732, and the portion 734 can define a coolant passage 738 extending along the length of the portion 734. The coolant passages 736 and 738 (also referred to as first passages) can be coupled together in fluid communication by a conduit/tube 740 at the second end portion 710 to form the coolant circuit 730. Referring to FIGS. 7 and 8, couplings/fittings 742 and 744 can be coupled to the passages 736 and 738, respectively, at the first end portion 708, which can connect the coolant circuit 730 to a coolant supply and/or heat exchanger located elsewhere in the assembly (e.g., outside the vacuum environment).

[0211] As noted above, in certain embodiments the additive manufacturing systems described herein can be operated in a vacuum environment, and the powder used to create the printed object/workpiece can be fused to the workpiece by an electron beam, an ion beam, a laser beam, or other energy beam. Heat radiated to the powder supply assembly 702 from the build platform, the energy beam, and/or other objects in the environmental chamber, can be removed by circulating coolant through the coolant circuit 730. In certain embodiments, heat transfer to the coolant can be primarily by conduction through the material of the powder container 703. In certain embodiments, the powder container 703 can comprise materials with relatively high thermal conductivity such as aluminum, steel, copper, etc.

[0212] In certain embodiments, parameters such as the volume flow rate, the diameter and/or surface area of the coolant passages 736 and 738, the type of coolant, etc., can be varied to maintain the powder supply assembly 702, the powder container 703, and/or the flow control assembly 706 within a specified temperature range. For example, in certain embodiments the fluid cooling system 729 can be configured to maintain the powder container 703 and/or the vibration generators at or below the sintering temperature of a specified powder material, such as titanium, copper, steel, etc., to prevent fusing/sintering of powder in the container during prolonged operation of the additive manufacturing system. Stated differently, the temperature of the powder container can be maintained at or below a specified temperature such that the powder maintains a powdery consistency and characteristics associated with powdered materials, such as freely flowing when tilted, for a given material. In certain embodiments, the sintering temperature can be 75% or less of the melting temperature of the powder material. In certain embodiments, the fluid cooling system 729 can be configured to maintain the powder container and/or the vibration generators at or below 600° C, such as at or below 500° C, at or below 400° C, at or below 300° C, at or below 200° C, or at or below 100° C.

[0213] Maintaining the temperature of the powder container 703, and thereby the vibration generators, within the temperature ranges above can also reduce the likelihood of heat-related failure of the vibration generators. Additionally, due to differences in the material of the vibration generators and the powder container 703, heating beyond a specified temperature can also lead to mismatches in the size of the vibration generators relative to the passages 728 in which they are situated. For example, over-expansion of the vibration generators relative to the passages 728 can damage or crush the vibration generators. Differences in size between the vibration generators and the passages 728 can also limit the ability of the vibration generators to vibrate the powder container and agitate the powder, which in turn can impede powder delivery to the workpiece. In certain embodiments, maintaining the temperature of the powder container 703 and/or the vibration generators within the ranges specified above can maintain the spatial relationship between the vibration generators and the passages 728 within specified tolerances. In particular embodiments, maintaining the temperature of the powder container 703 at or below 100° C can prolong the operating life of the vibration generators, and avoid heat-related degradation of the vibration generators and associated wire connections.

[0214] In certain embodiments, the coolant can be a liquid, such as filtered or distilled water, alcohol, a water-alcohol mixture, oil, etc.

[0215] The configuration of the powder container 703 and the coolant circuit 730 shown in FIGS. 7-10 is only one example, and many configurations are possible. For example, in certain embodiments the coolant passages 736 and 738 can be located in the sloped/angled portions of the side walls 716 and 718, e.g., among the passages 728. In certain embodiments, the coolant circuit 730 can extend through passages defined in the end walls 712 and/or 714 instead of, or in addition to, external conduits such as the conduit 740. In certain embodiments, the frame assembly 704 can comprise a liquid circuit instead of, or in addition to, the liquid circuit 730 of the powder container 703. In certain embodiments, the powder container 703 and/or the frame assembly 704 can comprise a coolant jacket or coolant-filled casing or volume of greater volume than the coolant passages 736 and 738, through which coolant can be circulated. In certain embodiments, the passages and fittings of the coolant circuit can be located below the passages for the vibration generators. In certain embodiments, the additive manufacturing system can also comprise a radiation shield member disposed between the powder supply assembly 702 and the energy beam, and/or between the build platform and the powder supply assembly, to limit thermal contact (e.g., by limiting radiative heat transfer) between the powder container assembly 702 and those components. In certain embodiments, the powder container assembly can comprise other temperature control elements in addition to the fluid cooling system, such as thermoelectric coolers and/or heaters as described above.

[0216] Referring again to FIGS. 7 and 8, in certain embodiments the powder container assembly 702 can be coupled to the support frame assembly 704, which can support the powder container assembly within the larger three-dimensional printing system. For example, with reference to FIG. 7, in the illustrated embodiment the supply frame assembly 704 can comprise a plurality of frame members coupled together, namely a first frame member 746 at a first end portion of the supply frame assembly, a second frame member 748 at a second end portion of the supply frame assembly, and third and fourth frame members 750 and 752 extending between the first and second frame members 746, 748 to define a volume sized and shaped to receive the power container 703.

[0217] In certain embodiments, the powder container assembly 702 and the support frame assembly 704 can be coupled together in a manner that permits motion of the powder container 703 relative to the supply frame assembly 704. In certain embodiments, motion of the powder container 703 relative to the powder supply assembly 704 can be within a specified range of motion determined at least in part by the coupling means between the powder container and the supply frame assembly. For example, with reference to FIG. 7, in the illustrated embodiment the powder container assembly 702 can be coupled to the supply frame assembly 704 by bolts/screws/fasteners 754 extending through openings 756 defined in the outer side edges/walls of the first and second frame members 746 and 748. FIG. 11 schematically illustrates a cross-sectional view through the assembled powder container assembly 702 and the supply frame assembly 704 showing representative fasteners 754 disposed in the openings 756 of the supply frame assembly. For ease of illustration, only one fastener 754 and opening 756 are shown on each side of the assembly in FIG. 11, although the system can comprise any number of fasteners and corresponding openings in the powder container and the supply frame assembly depending upon the particular requirements of the system.

[0218] In certain embodiments, the fasteners 754 can have a first diameter DI, and can be received in threaded engagement with corresponding openings schematically illustrated at 758 defined in the powder container 703. The openings 756 of the supply frame assembly 704 can comprise a second diameter D2 that is greater than the first diameter DI. Accordingly, the difference between the second diameter D2 and the first diameter DI can provide for a specified amount of relative movement between the powder container 703 and the supply frame assembly 704. In certain embodiments, the difference between the diameter D2 and the diameter DI can be 50 microns or less, 100 microns or less, 200 microns or less, 300 microns or less, 400 microns or less, 500 microns or less, 1,000 microns or less, from 50 microns to 1,000 microns, 100 microns to 500 microns, 100 microns to 400 microns, 100 microns to 300 microns, 100 microns to 200 microns, etc. Accordingly, during operation of the additive manufacturing system the powder container 703 can move relative to the frame assembly 704 by any of the distances specified above. In certain embodiments, the fasteners 754 can be shoulder bolts/screws. In certain embodiments, the fasteners 754 can comprise heads 755 having a diameter greater than the diameter D2. In certain embodiments the bolt heads 755 can constrain lateral movement of the powder container, although in other embodiments the bolts need not include heads. In certain embodiments, the interior of the supply frame assembly 704 can also be wider and/or longer than the powder container 703 such that there are gaps between the supply frame assembly and the powder container when the powder container is received in the supply frame assembly. In certain embodiments, this can facilitate movement of the powder container relative to the supply frame assembly.

Additionally, in the illustrated embodiment the openings 756 and 758 can be angled such that the fasteners 754 extend perpendicular or substantially perpendicular to the angled portions of the side walls of the powder container, although the fasteners and openings can define any angle with the walls of the powder container.

[0219] In certain embodiments, such relative movement between the powder container 703 and the supply frame assembly 704 can be advantageous to promote powder flow through the powder container 703 and reduce clumping of powder in the powder container. For example, a difference between the diameter DI of the fasteners and the diameter D2 of the openings 756 can allow the powder container to vibrate or rattle against the supply frame 704 during operation of the vibration generators. The rapid impulses imparted to the powder container 703 by vibrating against/contacting the supply frame assembly 704 can agitate the powder in the container, breaking up powder clumps and promoting more even flow of powder from the powder supply assembly onto the workpiece. Such movement or vibrating action can be particularly advantageous when using cohesive powders, such as metal powders having a particle size of 100 pm or less, such as 50 pm or less, and which can be prone to cohesively binding and forming clumps that impede powder flow. In certain embodiments, vibration of the powder container against/relative to the supply frame assembly can be facilitated by tuning the powder supply assembly such that it exhibits a resonance frequency corresponding to the frequency of the vibration generators, as described further below.

[0220] FIGS. 12-18 illustrate another embodiment of a powder supply assembly 800. Referring to FIGS. 12 and 13, the powder supply assembly 800 can comprise a powder container 802 including passages 804 defined in the side walls 806, 808 configured to receive vibration generators 818 (FIG. 15). In certain embodiments, the powder supply assembly can comprise a temperature control element such as a fluid cooling system similar to the system 729 described above. Accordingly, the powder container can further comprise coolant passages 810 and 811 defined in top portions of the side walls 806 and 808, respectively. The side walls 806 and 808 can also define a plurality of openings/slots 812 in communication with the passages 804. With reference to FIG. 15, the slots 812 can facilitate, for example, electrical connections 838 to the vibration generators at 818, fixation of the vibration generators 818 in the passages 804, etc. For example, in certain embodiments the vibration generators 818 can be secured in place in the passages by adhesive (e.g., epoxy) applied through the slots 812. FIG. 14 illustrates a flow restrictor configured as a mesh screen 814 that can be positioned against the lower surface of the powder container 802 to regulate flow of powder through the slot 816 defined between the side walls 806 and 808. FIG. 16 illustrates openings 820 defined in a supply frame assembly 821 configured to receive the powder container 802. The openings 820 can be configured to receive fastener members 840 (FIG. 14) similar to the fasteners 754 to allow vibration/movement of the powder container 802 relative to the supply frame assembly 821 or another external fixation/frame in order to promote powder flow out of the container as described above.

[0221] Referring to FIG. 17, in certain embodiments, the powder supply assembly 800 can define a coolant circuit 822 extending through the coolant passages 810 and 811 and through a conduit 824 connecting the passages 810 and 811 at one end of the powder container, similar to the coolant circuit 730. In certain embodiments, conduits 826 and 828 can extend from the passages 810 and 811. In certain embodiments, the conduits 826 and 828 can extend through the passages 810 and 811 and can be coupled to the conduit 824, for example, by fittings 830 and 832. The coolant circuit 822 can be in fluid communication with a coolant source and/or a heat exchanger elsewhere in the system, as described above. In certain embodiments, the powder container 802 can be formed by separable halves or members 834, 836, which can be coupled or secured together by bolts or other securing means.

[0222] The powder supply assemblies 700 and 800 can be used in combination with any of the additive manufacturing/three-dimensional printing systems and/or related subsystems described herein. In other embodiments, the coolant passages in each side wall of the powder container can be incorporated into separate coolant circuits, and the coolant passages need not be in fluid communication with each other.

[0223] Example 3: Powder Supply Assembly with Powder Level Sensor

[0224] In certain embodiments, the powder supply assemblies and/or powder container assemblies of the three-dimensional printing systems described herein can also include one or a plurality of powder level sensors configured to detect the presence and/or amount and/or height/level of powder contained in the powder container. In certain embodiments, the powder level sensors can be capacitive sensors, such as parallel electrode capacitive sensors, configured to detect a change in capacitance correlating with the presence, absence, and/or height/level of powder in the container.

[0225] For example, referring again to FIGS. 7-10, the powder supply assembly 700 can comprise a powder level sensor 770 coupled to and disposed within the volume of the powder container 703. More particularly, with reference to FIGS. 9A and 9B, the powder level sensor 770 can comprise a first electrode member 772 (also referred to as a first electrode) coupled to the first side wall 716, and a second electrode member 774 (also referred to as a second electrode) coupled to the second side wall 718. The first electrode member 772 can comprise an electrode portion 776 and a coupling or mounting portion 778 (FIGS. 8, 9A, and 9B). As best shown in FIG. 9A, in the illustrated embodiment the electrode portion 776 can comprise extension portions 776A and 776B extending from opposite sides of the mounting portion 778. Referring to FIG. 9B, an insulator member 780A can be positioned between the mounting portion 778 and the first wall 716 of the powder container 703 to electrically insulate/isolate the first electrode member 772 from the powder container, and space the electrode member 772 inwardly away from the first side wall 716.

[0226] The first electrode member 772 can be secured to the powder container by one or a plurality of fasteners. For example, in the illustrated embodiment two fasteners 782A and 782B are disposed through respective grommets or insulative bushings 784 A and 784B. The fasteners and bushings are positioned in respective recesses 785A and 785B (FIG. 9A) defined in the mounting portion 778. As shown in FIG. 9B, the fasteners 782A, 782B extend into and engage the first side wall 716 of the powder container. The bushings 784A, 784B can electrically insulate the first electrode member 772 from the fasteners 782A, 782B, and from the powder container 703.

[0227] The second electrode member 774 can be configured similarly to the first electrode member 772, and can comprise an electrode portion 786 and a mounting portion 788 coupled to the second side wall 718 by fasteners 782C and 782D (FIG. 9A). The fasteners can extend through respective insulative bushings 784C and 784D positioned in corresponding recesses defined in the mounting portion 788. As shown in FIG. 9B, the second electrode member 774 can be spaced inwardly from the second side wall 718 by an insulator member 780B. Referring to FIG. 9A, the second electrode member 774 can also comprise extension portions 786A and 786B extending from opposite sides of the mounting portion 788 parallel with the portions 776A and 776B of the first electrode member.

[0228] Referring again to FIG. 9B, the electrode portion 776 (including the extension portions 776A and 776B) of the first electrode member 772 can comprise an outer surface 790 that extends in the y-z plane of FIG. 9B. The electrode portion 786 (including the extension portions 786A and 786B) of the second electrode member 774 can comprise an outer surface 792 also extending in the y-z plane of FIG. 9B. The surfaces 790 and 792 can be in a parallel, or substantially parallel, opposed arrangement, and spaced apart by a specified distance d (also referred to herein as a gap). The surfaces 790 and 792 can also have the same or substantially the same area (e.g., ± 5%). Accordingly, the electrode members 772 and 774, and in particular embodiments the electrode portions 776 and 786, can form a parallel plate capacitor with a capacitance C given by the following equation, where k is the relative permittivity of the dielectric material between the electrode members, eo is the permittivity of free space, A is the area of the surfaces 790 and 792, and d is the distance/gap width between the surfaces 790 and 792.

[0229] In certain embodiments, the area A can be the area of the surfaces 790 and 792, or can be the total surface area of the portions of the electrodes oriented inwardly toward the interior of the powder container.

[0230] The gap between the electrodes 772 and 774 can be configured to allow powder to flow between the electrodes. In operation, the capacitance C between the first and second electrode members 772, 774 and/or their respective electrode portions 776 and 786, can vary in accordance with the level of the powder bed in the powder container 703. The powder bed level is indicated schematically at 781 in FIG. 9B. For example, as the powder level 781 rises between the electrode portions 776 and 786, the permittivity can increase, resulting in an increased capacitance C. Thus, using the permittivity k of the powder material, the capacitance C that is sensed/determined between the first and second electrode members 772 and 774 can be correlated with the level 781 of the powder bed and/or with the quantity (e.g., volume) of powder in the powder container 703.

[0231] In certain embodiments, the electrode members 772 and 774 can be made from any suitable electrical conductor, such as metals including copper, steel, aluminum, etc. In certain embodiments, the insulator members 780 A and 780B, and/or the insulative bushings 784A-784D, can comprise any suitable electrically insulative, heat resistant material, such as mica, any of various ceramic materials, glass (e.g., fiberglass), etc.

[0232] In certain embodiments, the electrode members 772 and 774 can extend along 50%, 60%, 70%, 80%, 90%, or 100% of the length of the powder container 703. In certain embodiments, the powder container 703 can comprise a plurality of powder level sensors positioned at different locations along the length, width, and/or height of the powder container to detect, for example, variation in the height of the powder bed at different locations in the powder container.

[0233] The powder level sensor 770 can be used in combination with any of the powder supply assemblies and/or additive manufacturing systems described herein.

[0234] Example 4: Powder Suppl Assembly and Suspension with Tuned Resonant Frequency

[0235] In certain embodiments, the powder supply assemblies and/or powder container assemblies of the three-dimensional printing systems described herein can also be configured to resonate at a specified frequency. In certain embodiments, the powder container assembly can be configured to vibrate relative to or against the support frame assembly, as described above. In certain embodiments, the resonant frequency of the powder container assembly can be configured or tuned to correspond to a frequency of the vibration generators. In certain embodiments, the direction of motion/vibration of the powder container assembly can be tuned/controlled to be along an axis that extends in the direction of powder flow through the powder container assembly (e.g., up and down in a system where the powder container is above the workpiece). In certain embodiments, this can significantly increase the amplitude of vibration of the powder supply assembly, which can improve powder flow out of the powder container and/or reduce the quantity, size, and/or power requirements of the vibration generator(s) needed to produce a specified powder flow.

[0236] In certain embodiments, resonance of the powder container assembly at a specified frequency can be achieved by supporting/suspending the powder container assembly or components thereof with a low-stiffness suspension or support system/assembly. One exemplary suspension system can include one or more flexure members coupling the powder container assembly to a rigid or stationary frame, and configured to allow the powder container assembly to move or vibrate relative to the stationary frame in the manner of a spring-mass system.

[0237] Any of various flexure configurations can be used, including, for example, pin flexures, blade flexures, notch flexures, and/or combinations thereof. In certain embodiments, blade flexures can be combined to allow motion of the powder container assembly up and down along the z-axis (see FIG. 22), while constraining motion of the powder container assembly in at least certain other degrees of freedom. For example, FIGS. 19A-19C illustrate the flexible modes of an exemplary blade flexure 902 constrained at one end, namely a primary bending or flexion mode along the z-axis (FIG. 19A), a secondary twisting mode about the x-axis (FIG. 19B), and a secondary twisting mode about the z-axis (FIG. 19C). The cantilevered blade flexure 902 can be relatively inflexible along the y-axis (FIG. 20A), relatively inflexible along the x-axis (FIG. 20B), and relatively inflexible in response to moment/rotation/twisting about the z-axis (FIG. 20C), and thus will not exhibit significant vibration in these modes.

[0238] Utilizing two blade flexures 902 spaced apart along the z-axis to cantilever or support a sprung mass 904 (e.g., a powder container assembly) from a rigid support/frame 912 as in FIG. 21 can provide for oscillatory motion in the primary flexible mode along the z-axis indicated by arrow 906, as well as rotational motion about the x-axis indicated by arrow 908 and at least some rotational motion about the z-axis as indicated by arrow 910. Supporting the sprung mass 904 between two sets of two blade flexures 902 coupled to rigid supports 912 as in FIG. 22 can significantly reduce or eliminate rotational motion of the sprung mass 904 about the z-axis.

[0239] In certain embodiments, the natural resonant frequency of the spring-mass system can be specified/tuned/designed by varying one or more parameters of the flexures 902, such as their length, width, thickness, material type, etc. For example, referring again to FIG. 19A the length L, the width W, and the thickness T can be varied to tune/vary the resonant frequencies of the system. In certain embodiments, the frequency of the mass-spring system can be proportional to

/k. where M is the mass supported k is the spring constant of the blade flexure. In certain embodiments, the stiffness of a blade flexure in the direction along 3 El the y-axis can be — , where E is the modulus of elasticity of the selected material and I is the

area moment of inertia of the flexure cross-section. In certain embodiments, the stiffness of a bh³ blade flexure can be proportional to — , where b is the width of the flexure cross-section, h is

the height of the flexure cross-section, and L is the length of the flexure. In certain embodiments, the frequency of the blade flexure can be proportional to the cube of the thickness (T³). In certain embodiments, the stress in the blade flexure can be proportional to 1

-. In certain embodiments, the length, width, and/or thickness of the blade flexures can be adjusted iteratively using a finite element analysis (FEA) model.

[0240] In certain embodiments, the powder container assembly can be suspended, supported by, or coupled to a suspension comprising an arrangement of blade flexures configured to promote vibration/oscillation/movement of the powder container assembly in one or more specified directions and/or vibration modes. Stated differently, the suspension can be tuned such that it vibrates at a specified resonant frequency (e.g., a fundamental vibrational mode) equal to or substantially equal to a frequency of the vibration generators of the system or other excitation. The suspension can be further configured to damp vibration in other modes, and/or to vibrate at relatively high frequency in other modes such that the powder container assembly exhibits relatively little vibration and/or transient vibration in modes other than the specified mode when excited at the specified frequency. [0241] For example, FIG. 23 illustrates a portion of another embodiment of a three- dimensional printing system 1000 comprising a powder supply assembly comprising a powder container assembly generally indicated at 1002. In FIG. 23 the powder container assembly 1002 is shown in perspective looking upwardly at the lower surface of the powder container 1004 and the flow control mesh 1006. The powder container 1004 and associated components are shown in dashed lines for purposes of illustration. In the illustrated configuration, the powder supply assembly 1002 is shown suspended by a suspension system 1008 comprising a plurality of blade flexures 1016. The blade flexures 1016 can be coupled to constraints 1012 which, in certain embodiments, can be stationary elements/members of the system such as the frame member/plate member 1014, walls of a housing or containment of the additive manufacturing system, or any other relatively stiff, stationary bodies. In certain embodiments, the suspension system 1008 can be configured to suspend the powder container 1004 and/or other elements of the powder supply assembly above the powder bed assembly.

[0242] In FIG. 23, the suspension system 1008 can include six blade flexure members 1016 arranged in pairs, with a first pair of flexure members 1016A and 1016B coupled to and extending between a constraint 1012A and the first end portion 1018 of the powder container 1004. A second pair of flexure members 1016C and 1016D can be coupled to a constraint 1012B and to the first side wall 1020 of the powder container 1004 at or near the second end portion 1022 of the powder container. A third pair of flexure members 1016E and 1016F can be coupled to a constraint 1012C and to the second side wall 1024 of the powder container 1004 on the opposite side of the powder container from the flexure members 1016C and 1016D. In certain embodiments, the first pair of flexure members 1016A and 1016B can be orthogonal to the other flexure members 1016C-1016F. In certain embodiments, the flexure members 1016C-1016F can be parallel or substantially parallel to each other, although other configurations are possible. The number and arrangement of flexure members in the illustrated embodiment can restrict motion of the powder container assembly to motion in one degree of freedom under normal operating conditions, namely motion along the z-axis. [0243] For example, in certain embodiments the spring-mass system including the powder container assembly 1002 and the suspension system 1008 as shown in FIG. 23 can be configured to exhibit a first order or primary mode resonance at 300 Hz along the z-axis. In embodiments in which the flexure members 1016 comprise a length of 210 mm, a width of 36 mm, and a thickness of 2 mm, and comprise 316 stainless steel, the internal stress can be 300 MPa at 3 mm of deflection. In certain embodiments, the powder container 1004 can oscillate at an amplitude of 0.1 mm to 2 mm, 0.1 mm to 1 mm, 2 mm or less, 1 mm or less, etc., during steady state excitation (e.g., at 300 Hz, or any specified excitation frequency).

[0244] In certain embodiments, the flexure members 1016 can comprise any of various metal materials and/or metal alloys, such as steel (e.g., spring steel), titanium, beryllium copper alloys, carbon steel, stainless steel, aluminum, etc., although in other embodiments the flexure members can comprise any material with sufficiently low outgassing properties in a vacuum environment.

[0245] In certain embodiments, the suspension system 1008 can include a fourth pair of flexure members extending from the second end portion 1022 of the powder container parallel or substantially parallel to the flexure members 1016A and 1016B. In certain embodiments, each grouping of flexure members can comprise more than two flexures or fewer than two flexures (e.g., a single flexure) depending upon the particular characteristics desired. For example, FIG. 27 illustrates an alternative spring-mass system in which the mass 904 is suspended between single blade flexures 902 instead of pairs. In certain embodiments, the flexure members of the suspension system 1008 can be arranged to accommodate conduits, fittings, etc., of a liquid coolant circuit 1010 of the powder supply assembly, which can be configured according to any of the embodiments described herein.

[0246] FIG. 24 illustrates another embodiment of the printing system 1000 in which the flexure members 1016 comprise a length of 30 mm, a thickness of 0.5 mm, and a width of 36 mm, and the system has a resonant frequency of 77 Hz in the first/primary mode, and 871 Hz in the second mode (e.g., rotation about the x-axis). In certain embodiments, the flexures can develop an internal stress of 200 MPa at a deflection of 0.5 mm. In certain embodiments, the configuration illustrated in FIG. 24 can oscillate with an amplitude of 0.5 mm when excited with an input frequency of 77 Hz.

[0247] FIG. 25 illustrates an alternative configuration of a flexure member 1016 of the embodiment of FIG. 23 in which the flexure member is folded or curved into an S -curve shape to save space. In certain embodiments, a suspension system 1008 including one or more (e.g., all) flexure members configured as shown in FIG. 25 can exhibit the same or substantially the same vibrational characteristics as straight flexures.

[0248] FIG. 26 illustrates a graphical representation of a finite element analysis (FEA) model of the spring-mass system including the suspension system 1008 and the powder container 1004 configured as shown in FIG. 24. In one embodiment, the powder container 1004 oscillated with an amplitude of 815 mm in the primary mode (along the z-axis in FIG. 24) when excited at the primary mode frequency of 77 Hz.

[0249] FIG. 28 illustrates an alternative embodiment of a spring-mass system 1100 in which the sprung mass 1102 (e.g., a powder container assembly) is constrained from moving in directions other than the direction of the primary mode vibration by constraints configured as journal bearings 1104.

[0250] In other embodiments, one or more of the flexures 1016 can be configured as pin flexures, notch flexures, and/or any other flexure design.

[0251] One or more of the additive manufacturing system embodiments described herein can provide significant advantages over existing additive manufacturing systems. For example, incorporating a coolant circuit into the powder supply assembly can significantly improve temperature control of sensitive components such as the vibration generators, and prevent fusing or sintering of powder in the powder container during sustained operation of the system, especially in a vacuum environment. Mounting the powder container to the supply frame assembly in a manner that permits vibration of the powder container against the frame can promote even, controlled powder flow out of the powder container, and can avoid the formation of powder clumps in the powder container. Additionally, suspending the powder supply assembly from a suspension system tuned to resonate at the frequency of the vibration generators can improve powder flow onto the workpiece by increasing the amplitude of vibrations of the powder container. In certain embodiments, this can allow for a reduction in the size and/or number of vibration generators needed to produce a specified powder flow, with associated reductions in power requirements and heat generation. The vibration generators can also be run at reduced power, which can prolong their life and increase the length of time between maintenance intervals.

[0252] Example 5: Temperature Control of Powder Suppl Assembly

[0253] As described above, in certain embodiments the powder supply assemblies described herein can include one or a variety of temperature control elements such as heaters (e.g., electric heaters), TECs, circulating liquid or fluid systems, etc., to maintain the temperature of the powder container, the powder, and/or various other components of the powder supply assembly within a specified temperature range. The following description refers to the temperature of the powder container for convenience, but it should be understood that maintaining the powder container within the specified temperature range also controls the temperature of powder in the powder container, as well as other components of the powder supply assembly such as the vibration generators.

[0254] In certain embodiments, maintaining the powder container within a specified temperature range can comprise heating the powder container instead of, or in addition to, cooling the powder container. Thus, in certain embodiments the fluid cooling system 729 (FIG. 7) can be operable to heat the powder container 703 as well as cool the powder container. The fluid cooling system 729 can thus be configured to operate as a temperature control system for controlling a temperature of the powder container and associated components. For example, in certain embodiments the temperature control system can circulate a heat transfer fluid such as any of the coolant liquids and gases described above through a fluid circuit (e.g., coolant circuit 730) including the passages 736 and 738 (also referred to as fluid passages) of the powder container 703 (FIG. 10). The heat transfer fluid can be at an elevated temperature to preheat the powder container 703. Such heating can be done prior to dispensing powder from the powder container (e.g., onto the build platform, or to another part of the system). In certain embodiments, it may be advantageous to heat the powder container 703 using a heat transfer fluid at the beginning of an operating session (e.g., before the additive manufacturing system has reached a steady-state operating temperature). As noted above, heat transfer between the powder container 703 and the heat transfer fluid can be primarily by conduction through the body of the powder container. Thus, in certain embodiments the powder container 703 can comprise a material with high thermal conductivity such as any of various metal materials including aluminum, steel, copper, titanium, tungsten, etc., or combinations thereof.

[0255] In certain embodiments, the temperature control system can adjust the temperature of the heat transfer fluid during operation of the additive manufacturing system to maintain the temperature of the powder container within a selected temperature range, such as any of the temperature ranges given above. For example, as components of the additive manufacturing system heat up during sustained operation, the temperature of the heat transfer fluid can be reduced as the need for heating transitions to a need for cooling to maintain the powder container in the selected temperature range. Accordingly, the temperature control system can include components such as heat exchangers, chillers, heaters (e.g., electric heaters), thermostats or other temperature sensor and/or control devices, pumps, condensers, etc., in communication with the fluid circuit. Thus, the heat transfer fluid can be at ambient temperature (e.g., the ambient temperature outside the build chamber, such as 5° C to 25° C), heated above ambient temperature, and/or chilled below ambient temperature, depending upon the particular requirements of the system.

[0256] Representative examples of heat transfer fluids that can be used in combination with the systems described herein include aqueous heat transfer fluids/liquids such as water, alcohol (e.g., ethylene glycol, propylene glycol, etc.), and water-alcohol mixtures. Aqueous heat transfer fluids can be circulated through the powder container 703 at temperatures ranging from -30° C to 100° C (e.g., depending on the type and concentration of any freezing point depressants, such as alcohol). For example, aqueous heat transfer fluids can be circulated through the powder container 703 at temperatures ranging from -10° C to 100 ° C, 0° C to 100° C, 1° C to 100° C, 5° C to 100° C, 5° C to 80° C, 5° C to 50° C, 5° C to 30° C, 100° C or less, 80° C or less, 50° C or less, 30° C or less, etc. In particular embodiments, the heat transfer fluid can comprise water circulated at a temperature of 5° C to 25° C, such as 18° C.

[0257] Representative examples of heat transfer fluids can also include oil, and/or liquid organic compounds including alkyl-containing heat transfer fluids, ether-containing heat transfer fluids, silicone-containing heat transfer fluids, etc. Heat transfer fluids comprising oil or liquid organic compounds can be circulated through the powder container 703 at temperatures ranging from -30° C to 600° C, such as -30° C to 400° C, 0° C to 400° C, 50° C to 400° C, 100° C to 400° C, 100° C to 350° C, 50° C to 350° C, 10° C to 200° C, 10° C to 100° C, 600° C or less, 400° C or less, 350° C or less, 300° C or less, 200° C or less, 100° C or less, etc. In certain embodiments, heat transfer fluids comprising oil or liquid organic compounds can undergo a phase change (e.g., from a liquid to a vapor or vice versa) during circulation through the powder supply assembly, depending upon the particular heating or cooling requirements of the system.

[0258] The flow rate of the heat transfer fluid through the powder container 703 (and/or the temperature control system) can vary depending upon a variety of factors including the selected temperature of the powder container, the heat load, the temperature of the ambient environment in the additive manufacturing system, the diameter of the pipes/conduits, etc. Representative flow rates can range from 0.1 L/min to 2 L/min, such as 0.25 L/min to 2 L/min, 0.25 L/min to 1.5 L/min, 0.5 L/min to 1.5 L/min, 0.5 L/min to 1 L/min, 2 L/min or less, 1.5 L/min or less, 1 L/min or less, etc.

[0259] In certain embodiments, the temperature control system can operate together with other temperature control elements such as heaters, TECs, etc., to heat and/or cool the powder container. In certain embodiments, a controller such as the control system 24 can control operation of the temperature control system (e.g., the temperature of the heat transfer fluid, the flow rate of the heat transfer fluid, etc.) to control the temperature of the powder container and/or maintain the powder container within a specified temperature range. In certain embodiments, the controller can control operation of the temperature control system in conjunction with other temperature control elements such as heaters, TE modules, etc., to control the temperature of the powder container and/or maintain the powder container within a specified temperature range.

[0260] For example, in certain embodiments the temperature in the vicinity around the powder container can change significantly during the manufacture of an object. The radiative heat transfer to the powder container from other objects in the vacuum environment can also change during manufacture of an object, for example, due to changes in the view factor as various components of the system move relative to one another. When the build platform and/or the energy beam/heat source are near the powder container, heat transfer to the powder container can be relatively high (e.g., the components radiating to the powder container can be at a temperature of 500° C to 1,500° C, depending upon the particular material being used to form the object). When the build platform and/or the energy beam move away from the powder container (thereby reducing the view factor with the powder container and/or moving behind other, cooler objects in the chamber), heat transfer to the powder container can be lower (e.g., objects radiating to the powder container can be at a temperature of 500° C or less, such as 300° C or less, 200° C or less, 100° C or less, -30° C to 500° C, -30° C to 300° C, -30° C to 200° C, -30° C to 100° C, 0° C to 100° C, 0° C to 200° C, 0° C to 300° C, 0° C to 500° C, etc.). Thus, in order to maintain a powdered material in the powder container within a selected temperature range, the temperature control system can heat and/or cool the powder container during production of an object as the radiative heat transfer to the powder container changes, and/or as the temperature of the immediate environment around the powder container changes. For example, in certain embodiments it can be advantageous to maintain powdered stainless steel materials at a temperature range of 200° C to 500° C, and the temperature of the powder container can be controlled using the temperature control system and/or various other temperature control elements to alternatingly heat and cool the powder container as the additive manufacturing system operates. Further, it can also be advantageous in certain embodiments to heat the powder container to reduce temperature mismatch between the powder container and the build platform, which can cool the build platform (e.g., when the build platform is adjacent the powder container). [0261] The systems and methods described herein can also be useful for drying powder in the powder container, which can avoid clumping and/or the formation of powder lumps. When drying the powder, the temperature control system (e.g., heaters and/or the heat transfer fluid circuit) can heat the powder container to a specified temperature range (e.g., 100° C or greater).

[0262] Additional Examples of the Disclosed Technology

[0263] In view of the above described implementations of the disclosed subject matter, this application discloses the additional examples enumerated below. It should be noted that one feature of an example in isolation or more than one feature of the example taken in combination and, optionally, in combination with one or more features of one or more further examples are further examples also falling within the disclosure of this application.

[0264] Example 1. A powder supply assembly for an additive manufacturing system that manufactures an object on a build platform from a powder, the powder supply assembly comprising: a powder container configured to retain a powder and having a supply outlet facing the build platform; and a flow control assembly configured to control a flow of powder from the powder container toward the build platform; wherein the powder container comprises a temperature control element to maintain the powder container within a selected temperature range.

[0265] Example 2. The powder supply assembly of any example herein, particularly example 1 , further comprising a supply frame assembly configured to receive the powder container, and wherein the powder container is secured to the supply frame assembly and movable relative to the supply frame assembly to agitate powder in the powder container.

[0266] Example 3. The powder supply assembly of any example herein, particularly example 2, wherein the powder container is secured to the supply frame assembly by fasteners.

[0267] Example 4. The powder supply assembly of any example herein, particularly example 3, wherein the fasteners extend through openings defined in the supply frame assembly, and the openings have a diameter greater than a diameter of the fasteners. [0268] Example 5. The powder supply assembly of any example herein, particularly example 4, wherein a difference between the diameter of the openings and the diameter of the fasteners is 500 microns or less, 400 microns or less, 300 microns or less, 200 microns or less, or 100 microns or less.

[0269] Example 6. An additive manufacturing system comprising the powder supply assembly of any example herein.

[0270] Example 7. The additive manufacturing system of any example herein, particularly example 6, further comprising: a build platform; and a suspension assembly configured to suspend the powder supply assembly over the build platform to distribute a powder onto the build platform, wherein the suspension assembly and the powder supply assembly are configured to resonate at a frequency of the flow control assembly.

[0271] Example 8. The additive manufacturing system of any example herein, particularly example 6 or example 7, wherein the flow control assembly comprises a vibration generator.

[0272] Example 9. The additive manufacturing system of any example herein, particularly any one of examples 6 to 8, wherein the suspension assembly comprises a plurality of flexures.

[0273] Example 10. The additive manufacturing system of any example herein, particularly example 9, wherein the flexures are configured as blade flexures.

[0274] Example 11. The additive manufacturing system of any example herein, particularly examples 9 or 10, wherein the flexures are arranged in pairs.

[0275] Example 12. The additive manufacturing system of any example herein, particularly any one of examples 7 to 11, wherein the suspension assembly is configured to oscillate along an axis extending in a direction of powder flow through the powder container.

[0276] Example 13. The additive manufacturing system of any example herein, particularly any of examples 7 to 12, wherein the suspension assembly is configured to constrain motion of the powder container in directions other than the direction of powder flow through the powder container. [0277] Example 14. The additive manufacturing system of any example herein, particularly any one of examples 6 to 13, further comprising a powder level sensor configured to detect a level of powder in the powder container.

[0278] Example 15. The additive manufacturing system of any example herein, particularly example 14, wherein the powder level sensor comprises two electrodes disposed in the powder container and defining a gap configured such that powder can flow between the electrodes.

[0279] Example 16. A method, comprising producing a three-dimensional object with the additive manufacturing system of any example herein, particularly any of examples 6-15.

[0280] Example 17. An additive manufacturing system, comprising: a powder supply assembly comprising: a powder container configured to retain a powder; and a flow control assembly configured to control a flow of powder from the powder container; a build platform; and a suspension assembly configured to suspend the powder supply assembly over the build platform to distribute a powder onto the build platform, wherein the suspension assembly and the powder supply assembly are configured to resonate at a frequency of the flow control assembly.

[0281] Example 18. The additive manufacturing system of any example herein, particularly example 17, wherein the powder container comprises a temperature control element.

[0282] Example 19. The additive manufacturing system of any example herein, particularly example 17 or example 18, wherein the powder container defines passages for conducting a fluid through a body of the powder container to maintain the powder container within a selected temperature range.

[0283] Example 20. A powder supply assembly for an additive manufacturing system, comprising: a powder container configured to retain a powder; and a flow control assembly configured to control a flow of powder from the powder container; wherein the powder container comprises a temperature control element. [0284] Example 21. The powder supply assembly of any example herein, particularly example 20, wherein the temperature control element is configured to maintain the powder container at a temperature below a sintering temperature of the powder.

[0285] Example 22. The powder supply assembly of any example herein, particularly example 20 or 21, wherein the temperature control element includes a heater.

[0286] Example 23. The powder supply assembly of any example herein, particularly any one of examples 20-22, wherein the temperature control element comprises an electronic cooling device.

[0287] Example 24. The powder supply assembly of any example herein, particularly any one of examples 20-23, wherein the temperature control element comprises a fluid cooling system.

[0288] Example 25. The powder supply assembly of any example herein, particularly example 24, wherein the fluid cooling system comprises a coolant circuit that extends through coolant passages defined in the powder container.

[0289] Example 26. The powder supply assembly of any example herein, particularly example 25, wherein the powder container comprises first and second side walls, the first and second side walls defining coolant passages.

[0290] Example 27. The powder supply assembly of any example herein, particularly example 25 or 26, wherein the coolant passage of the first side wall is in fluid communication with the coolant passage of the second side wall by a conduit extending between the first side wall and the second side wall.

[0291] Example 28. The powder supply assembly of any example herein, particularly example 26 or 27, wherein at least portions of the first and second side walls are angled toward each other in a direction of powder flow through the powder container.

[0292] Example 29. The powder supply assembly of any example herein, particularly any one of examples 20-28, wherein the flow control assembly comprises a vibration generator. [0293] Example 30. The powder supply assembly of any example herein, particularly example 29, wherein the powder container is configured to receive the vibration generator.

[0294] Example 31. The powder supply assembly of any example herein, particularly example 30, wherein the vibration generator is received in a passage defined in the powder container.

[0295] Example 32. The powder supply assembly of any example herein, particularly example 31, wherein the passage is defined in a sloped portion of a side wall of the powder container.

[0296] Example 33. The powder supply assembly of any example herein, particularly examples 30-32, wherein the powder container comprises a plurality of passages configured to receive a plurality of vibration generators.

[0297] Example 34. The powder supply assembly of any example herein, particularly example 33, wherein the powder container defines a plurality of openings through side walls of the powder container, the openings being in communication with the passages to provide access to the vibration generators.

[0298] Example 35. The powder supply assembly of any example herein, particularly examples 25-34, wherein: the powder container defines a volume configured to retain powder; and the coolant circuit is offset from the volume along an axis extending in a direction of powder flow through the powder container such that the coolant circuit is higher than the volume.

[0299] Example 36. The powder supply assembly of any example herein, particularly examples 20-35, wherein the flow control assembly further comprises a mesh screen positioned adjacent an opening of the powder container.

[0300] Example 37. The powder supply assembly of any example herein, particularly examples 20-36, wherein the powder container comprises a multi-part assembly.

[0301] Example 38. The powder supply assembly of any example herein, particularly examples 20-37, wherein the temperature control element is configured to maintain the powder container at a temperature of 600° C or less, 500° C or less, 400° C or less, or 300° c or less.

[0302] Example 39. The powder supply assembly of any example herein, particularly examples 20-38, further comprising a supply frame assembly configured to receive the powder container, and wherein the powder container is secured to the supply frame assembly and movable relative to the supply frame assembly to agitate powder in the powder container.

[0303] Example 40. The powder supply assembly of any example herein, particularly example 39, wherein the powder container is secured to the supply frame assembly by fasteners.

[0304] Example 41. The powder supply assembly of any example herein, particularly example 40, wherein the fasteners extend through openings defined in the supply frame assembly, and the openings have a diameter greater than a diameter of the fasteners.

[0305] Example 42. The powder supply assembly of any example herein, particularly example 41, wherein a difference between the diameter of the openings and the diameter of the fasteners is 500 microns or less, 400 microns or less, 300 microns or less, 200 microns or less, or 100 microns or less.

[0306] Example 43. An additive manufacturing system comprising the powder supply assembly of any example herein, particularly any one of examples 20-42.

[0307] Example 44. The additive manufacturing system of any example herein, particularly example 43, further comprising: a build platform; and a suspension assembly configured to suspend the powder supply assembly over the build platform to distribute a powder onto the build platform, wherein the suspension assembly and the powder supply assembly are configured to resonate at a frequency of the flow control assembly.

[0308] Example 45. The additive manufacturing system of any example herein, particularly example 43 or 44, wherein the flow control assembly comprises a vibration generator. [0309] Example 46. The additive manufacturing system of any example herein, particularly any one of examples 43 to 45, wherein the suspension assembly comprises a plurality of flexures.

[0310] Example 47. The additive manufacturing system of any example herein, particularly example 46, wherein the flexures are configured as blade flexures.

[0311] Example 48. The additive manufacturing system of any example herein, particularly example 46 or 47, wherein the flexures are arranged in pairs.

[0312] Example 49. The additive manufacturing system of any example herein, particularly any one of examples 44 to 48, wherein the suspension assembly is configured to oscillate along an axis extending in a direction of powder flow through the powder container.

[0313] Example 50. The additive manufacturing system of any example herein, particularly any of examples 44 to 49, wherein the suspension assembly is configured to constrain motion of the powder container in directions other than the direction of powder flow through the powder container.

[0314] Example 51. The additive manufacturing system of any example herein, particularly any one of examples 43 to 50, further comprising a powder level sensor configured to detect a level of powder in the powder container.

[0315] Example 52. The additive manufacturing system of any example herein, particularly example 51, wherein the powder level sensor comprises two electrodes disposed in the powder container and defining a gap configured such that powder can flow between the electrodes.

[0316] Example 53. A method, comprising producing a three-dimensional object with the additive manufacturing system of any example herein, particularly any one of examples 43- 52.

[0317] Explanation of Terms

[0318] For purposes of this description, certain aspects, advantages, and novel features of the embodiments of this disclosure are described herein. The disclosed methods, apparatus, and systems are not limiting in any way. Instead, the present disclosure is directed toward all novel features and aspects of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The methods, apparatus, and systems are not limited to any specific aspect or feature or combination thereof, nor do the disclosed embodiments require that any one or more specific advantages be present or problems be solved. The scope of this disclosure includes any features disclosed herein combined with any other features disclosed herein, unless physically impossible.

[0319] Although the operations of some of the disclosed embodiments are described in a particular, sequential order for convenient presentation, it should be understood that this manner of description encompasses rearrangement, unless a particular ordering is required by specific language set forth herein. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed components can be used in conjunction with other components.

[0320] As used in this disclosure and in the claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the term “includes” means “comprises.” Further, the terms “coupled” and “associated” generally mean electrically, electromagnetically, and/or physically (e.g., mechanically or chemically) coupled or linked and does not exclude the presence of intermediate elements between the coupled or associated items absent specific contrary language.

[0321] In some examples, values, procedures, or apparatus may be referred to as “lowest,” “best,” “minimum,” or the like. Such descriptions are intended to indicate that a selection among many alternatives can be made, and such selections need not be better, smaller, or otherwise preferable to other selections.

[0322] In the description, certain terms may be used such as "up," "down," "upper," "lower," "horizontal," "vertical," "left," "right," and the like. These terms are used, where applicable, to provide some clarity of description when dealing with relative relationships. But, these terms are not intended to imply absolute relationships, positions, and/or orientations. For example, with respect to an object, an "upper" surface can become a "lower" surface simply by turning the object over. Nevertheless, it is still the same object.

[0323] Unless otherwise indicated, all numbers expressing frequencies, material quantities, angles, pressures, molecular weights, percentages, temperatures, times, and so forth, as used in the specification or claims are to be understood as being modified by the term

“about.” Accordingly, unless otherwise indicated, implicitly or explicitly, the numerical parameters set forth are approximations that can depend on the desired properties sought and/or limits of detection under test conditions/methods familiar to those of ordinary skill in the art. When directly and explicitly distinguishing embodiments from discussed prior art, the embodiment numbers are not approximates unless the word “about” is recited. Furthermore, not all alternatives recited herein are equivalents.

[0324] Although there are alternatives for various components, parameters, operating conditions, etc., set forth herein, that does not mean that those alternatives are necessarily equivalent and/or perform equally well. Nor does it mean that the alternatives are listed in a preferred order unless stated otherwise.

[0325] In view of the many possible embodiments to which the principles of the disclosed technology may be applied, it should be recognized that the illustrated embodiments are only examples and should not be taken as limiting the scope of the disclosure. Rather, the scope of the disclosure is at least as broad as the following claims and their equivalents. We therefore claim all that comes within the scope and spirit of these claims.

Claims

CLAIMS:

1. A powder supply assembly for an additive manufacturing system that manufactures an object on a build platform from a powder, the powder supply assembly comprising: a powder container configured to retain a powder and having a supply outlet facing the build platform; and a flow control assembly configured to control a flow of powder from the powder container toward the build platform; wherein the powder container comprises a temperature control element to maintain the powder container within a selected temperature range.

2. The powder supply assembly of claim 1 , wherein the temperature control element is configured to maintain the powder container at a selected temperature below a sintering temperature of the powder.

3. The powder supply assembly of claim 1 or claim 2, wherein the temperature control element is configured to maintain the powder container at a temperature of 100° C or greater.

4. The powder supply assembly of any one of claims 1-3, wherein the temperature control element includes a heater.

5. The powder supply assembly of any one of claims 1-4, wherein the temperature control element includes an electronic cooling device.

6. The powder supply assembly of any one of claims 1-5, wherein the temperature control element comprises passages defined in the powder container for conducting a fluid through a body of the powder container.

- 69 -

7. The powder supply assembly of claim 6, wherein the passages are part of a coolant circuit of a fluid cooling system configured to maintain the powder container within the selected temperature range.

8. The powder supply assembly of claim 7, wherein the fluid cooling system is configured to maintain the powder container at or below 100° C.

9. The powder supply assembly of any one of claims 7 or 8, wherein the fluid cooling system is configured to maintain the powder container at a temperature below a sintering temperature of the powder.

10. The powder supply assembly of any one of claims 6-9, wherein: the powder container defines a volume configured to retain powder; and the passages of the powder container are offset from the volume along an axis extending in a direction of powder flow through the powder container.

11. The powder supply assembly of claim 10, wherein the passages of the powder container are above the volume configured to retain powder.

12. The powder supply assembly of any one of claims 6-11, wherein the powder container comprises first and second side walls, and the passages are defined in the first and second side walls.

13. The powder supply assembly of claim 12, wherein: the first side wall defines a passage; the second side wall defines a passage; and the passage of the first side wall is in fluid communication with the passage of the second side wall.

- 70 -

14. The powder supply assembly of claim 13, wherein the passage of the first side wall is in fluid communication with the passage of the second side wall by a conduit extending between the first side wall and the second side wall.

15. The powder supply assembly of any one of claims 12-14, wherein at least portions of the first and second side walls are angled toward each other in a direction of powder flow through the powder container.

16. The powder supply assembly of any one of claims 6-15, wherein the flow control assembly comprises a vibration generator.

17. The powder supply assembly of claim 16, wherein the vibration generator is received within the body of the powder container.

18. The powder supply assembly of claim 17, wherein: the passages defined in the powder container are first passages; and the vibration generator is received in a second passage defined in the powder container.

19. The powder supply assembly of claim 18, wherein the second passage is defined in a sloped portion of a side wall of the powder container.

20. The powder supply assembly of any one of claims 18 or 19, wherein the powder container comprises a plurality of second passages configured to receive a plurality of vibration generators.

21. The powder supply assembly of claim 20, wherein the powder container defines a plurality of openings through side walls of the powder container, the openings being in communication with the second passages to provide access to the vibration generators.

- 71 -

22. The powder supply assembly of any one of claims 16-21, wherein the vibration generator is offset from the passages for conducting fluid along a direction of powder flow through the powder container.

23. The powder supply assembly of any preceding claim, wherein the flow control assembly further comprises a mesh screen positioned adjacent an opening of the powder container.

24. The powder supply assembly of any preceding claim, wherein the powder container comprises a multi-part assembly.

25. The powder supply assembly of any preceding claim, wherein the powder container comprises a metal material.

26. The powder supply assembly of any one of claims 6-25, wherein the fluid is water, alcohol, a water-alcohol mixture, or oil.

27. The powder supply assembly of claim 6, wherein the passages are part of a fluid circuit of a temperature control system operable to heat the powder container and cool the powder container by circulating a heat transfer fluid through the passages.

28. The powder supply assembly of claim 27, wherein the temperature control system is configured to circulate the heat transfer fluid through the passages of the powder container to heat the powder container.

29. The powder supply assembly of any one of claim 27 or claim 28, wherein the temperature control system is configured to circulate the heat transfer fluid through the passages of the powder container to cool the powder container.

- 72 -

30. The powder supply assembly of any one of claims 27-29, wherein the temperature control system is configured to adjust a temperature of the heat transfer fluid circulating through the passages of the powder container to maintain the powder container within the selected temperature range.

31. The powder supply assembly of claim 30, wherein the selected temperature range is at or below 600° C, at or below 500° C, at or below 400° C, at or below 300° C, at or below 200° C, or at or below 100° C.

32. The powder supply assembly of any one of claims 27-31, wherein the heat transfer fluid comprises an aqueous liquid, oil, or a liquid organic compound.

33. An additive manufacturing system comprising the powder supply assembly of any preceding claim.

34. A method, comprising producing a three-dimensional object with the additive manufacturing system of claim 33.

35. A method, comprising: controlling a temperature of a powder container of an additive manufacturing system to maintain the powder container within a specified temperature range; controlling a flow of powder from the powder container with a flow control assembly of the additive manufacturing system; and supplying the powder from the powder container toward a build platform of the additive manufacturing system on which an object is manufactured from powder.

36. The method of claim 35, wherein the temperature of the powder container is maintained at a temperature below a sintering temperature of the powder.

- 73 -

37. The method of claim 35 or claim 36, wherein the temperature of the powder container is maintained at a temperature higher than 100° C.

38. The method of any one of claims 35-37, wherein controlling the temperature of the powder container is performed by an electric heater, an electric cooling device, or any combination thereof.

39. The method of any one of claims 35-38, wherein controlling the temperature of the powder container includes circulating a fluid through passages defined in a body of the powder container.

40. The method of claim 39, wherein circulating the fluid further comprises circulating the fluid through the passages of the powder container to maintain the powder container at or below 100° C.

41. The method of claim 39, wherein circulating the fluid further comprises circulating the fluid through the passages of the powder container to maintain the powder container below a sintering temperature of the powder.

42. The method of any one of claims 39-41, wherein maintaining the powder container within the specified temperature range comprises cooling the powder container, and a temperature of the fluid is 5° C to 25° C.

43. The method of claim 39, wherein maintaining the powder container within the specified temperature range comprises heating the powder container, and a temperature of the fluid is 50° C to 400° C.

44. The method of any one of claims 39-43, wherein the fluid comprises an aqueous heat transfer fluid.

- 74 -

45. The method of any one of claims 39-44, wherein the fluid comprises water.

46. The method of any one of claims 39-43, wherein the fluid comprises oil or a liquid organic compound.

47. A powder supply assembly for an additive manufacturing system, comprising: a powder container configured to retain a powder; and a flow control assembly configured to control a flow of powder from the powder container; wherein the powder container includes fluid passages defined in a body of the powder container for conducting a heat transfer fluid through the powder container to control a temperature of the powder container.