POWDERED MATERIALS

Cross Reference to Related Applications

[001] This non-provisional patent application claims priority to U.S. Provisional Application Serial Number 62/564,492, Entitled "HIGH CAPACITY APPARATUS FOR LAYERED MANUFACTURING FROM POWDERED MATERIALS" by Jonas Van Vaerenbergh et al., filed on September 28, 2017, incorporated herein by reference under the benefit of U.S.C. 119(e).

Field of the Invention

[002] The present disclosure concerns an apparatus and method for the digital fabrication of three dimensional (3D) articles utilizing powder materials. More particularly, the present disclosure concerns a very compact and high capacity powder handling system.

Background

[003] Three dimensional (3D) printing systems are in rapidly increasing use for purposes such as prototyping and manufacturing. One type of three dimensional printer utilizes a layer-by-layer process to form a three dimensional article of manufacture from powdered materials. One challenge with this process is to design a system for fabricating large articles. This is particularly an issue when certain portions of a printing system must be operated in a vacuum or with a controlled atmosphere.

Brief Description of the Figures

[004] FIG. 1 is a isometric illustration of an exemplary three dimensional printing system. In this view a front door is removed to illustrate components within a lower vacuum chamber.

[005] FIG. 2 is a front view of an exemplary three dimensional printing system.

In this view a front door is removed to illustrate components within a lower vacuum chamber.

[006] FIG. 3 is an isometric schematic illustration of modules for storing and transporting powder.

[007] FIG. 4 is an isometric illustration of a build module atop a powder storage module with a front panel removed for illustrative purposes.

[008] FIG. 5A is a side view of a vertical powder transport module.

[009] FIG. 5B is a more detailed view of a lower end of the vertical powder transport module.

[0010] FIG. 5C is an image of a lower portion of a helical screw used for powder transport.

[0011] FIG. 6 is an isometric illustration of an upper portion of a build module along with a vertical transport module, a fixed hopper, and a translating powder coater.

[0012] FIG. 7A depicts an initial state of a three dimensional printing system with a full powder storage module prior to the beginning of a printing operation. [0013] FIG. 7B depicts the beginning of the printing operation.

[0014] FIG. 7C depicts a later stage of the printing operation.

[0015] FIG. 7D depicts a completed printing operation.

[0016] FIG. 8 is an isometric schematic illustration of exemplary modules for storing and transporting powder.

Summary

[0017] In a first aspect of the disclosure, a three dimensional printing system for fabricating a three dimensional article of manufacture in a layer-by-layer manner includes a build module, a powder storage module, a powder transport conduit, a vertical powder transport module, and a powder layering apparatus. The build module has a lateral side and includes a vertically displaceable build platform for receiving layers of powder during the fabrication of the three dimensional article of manufacture. The powder storage module is located at least partially below the build module. The powder storage module has a lateral side and defines an internal volume for holding powder. The powder transport conduit transports the powder to a lateral location that is laterally offset from the lateral side of the powder storage module. The vertical powder transport module is laterally offset from the lateral side of the build module and the powder storage module and includes a lower end for receiving powder from the lateral location and an upper end having a laterally extending powder outlet. The powder layering apparatus is configured to receive the powder from the laterally extending powder outlet and to form layers of the powder over the build platform.

[0018] In one implementation the build module includes a central build chamber containing the vertically displaceable build platform and an overflow chamber between the build chamber and the lateral side of the build module. The overflow chamber can extend around all four sides of the central build chamber. Alternatively the overflow chamber can include two or more separate chambers.

[0019] In another implementation the powder storage module has a lower portion that is adjacent to the powder transport module. The powder transport module is horizontal and contains a motorized rotating helical screw. The powder transport module receives powder from the lower portion of the powder storage module. The rotating helical screw transports the powder laterally to the lateral location.

[0020] In yet another implementation the internal volume of the powder storage module includes a portion that tapers downwardly toward a powder outlet. The powder transport conduit is a vibratory chute that slopes downwardly and laterally from the powder outlet to the lateral location.

[0021] In a further implementation the powder transport conduit includes an

extension of the internal volume of the powder storage module. The extension of the internal volume couples to the vertical powder transport module.

[0022] In a yet further implementation a powder tank is located at the lateral location. The powder transport conduit couples a lower portion of the powder storage module to the powder tank. The vertical transport module extends upwardly from the powder tank.

[0023] In another implementation the vertical powder transport module is a

vertical tube with an internal helical screw whereby motorized rotation of the internal screw raises the powder up through the tube.

[0024] In yet another implementation the powder layering apparatus includes a fixed hopper and a translating dispenser, the laterally extending powder outlet dispenses powder into the fixed hopper, the fixed hopper dispenses powder into the translating dispenser. The translation dispenser is configured to form layers of powder while moving in either of two opposing directions. [0025] In a further implementation the three dimensional printing system includes a vacuum chamber that contains the build module, the storage module, the powder transport conduit, the vertical powder transport module, and the powder layering apparatus. The three dimensional printing system also includes a gas handling system that backfills the vacuum chamber with a non-oxidizing gas such as nitrogen or argon.

[0026] In a second aspect of the disclosure a system for fabricating a three

dimensional article of manufacture in a layer-by-layer manner includes a build module, a powder storage module, a powder transport conduit, a powder tank, a vertical powder transport module, a fixed hopper (rail-mounted but fixed during operation), and a translating powder coater. The build module has a lateral side and includes a vertically displaceable build platform for receiving layers of powder during the fabrication of the three dimensional article of manufacture. The powder storage module is located at least partially below the build module. The powder storage module has a lateral side, defines an internal volume for holding powder, and includes a lower portion that receives powder from the internal volume. The powder transport conduit receives powder from the lower portion of the powder storage module and transports the powder to the powder tank. The vertical powder transport module is laterally offset from the lateral sides of the build module and the powder storage module and includes a lower end for receiving powder from the powder tank and an upper end having a laterally extending outlet. The fixed hopper is positioned above the build module. An upper portion of the hopper receives powder from the laterally extending outlet of the vertical powder transport module. The hopper extends downwardly to a dispensing end. The dispensing end of the hopper is positioned above the build module proximate to the lateral side. The powder coater moves laterally across the build module for depositing layers of powder upon the build platform, the powder coater receives powder by positioning under the dispensing end of the fixed hopper. [0027] In one implementation the build module includes a central build chamber containing the vertically displaceable build platform and an overflow chamber portion between the build chamber and the lateral side of the build module. The powder coater parks or stops over the overflow chamber portion to receive powder from the dispensing end of the hopper.

Detailed Description of the Preferred Embodiments

[0028] FIG. 1 is an isometric illustration of an exemplary three dimensional (3D) printing system 2 with some features missing for illustrative purposes. In describing three dimensional printing system 2, mutually orthogonal axes X, Y, and Z will be used. The axes X and Y will be referred to as "lateral" axes. The direction -X is left and +X is right. The direction +γ is toward the back and the direction -Y is toward the front. The axis Z will be referred to as a "vertical" axis with +Z being an upward direction and -Z being a downward direction.

[0029] The three dimensional printing system 2 has a main chassis 4 and

peripheral components such as high powered laser engine 6 and gas handling system 8. High powered laser engine 6 includes one or more high powered lasers that can output laser optical power from hundreds of watts to more than 1000 watts for the purpose of the high speed melting of metal powder layers. The output from laser engine 6 is an optical signal that is carried by a fiber optical path into the main chassis 4. The gas handling system 8 is configured to evacuate a chamber within the main chassis 4 and to backfill it with a non- oxidizing or inert gas such as argon or nitrogen.

[0030] FIG. 2 is a front schematic view of the three dimensional printing system 2 with some features missing for illustrative purposes. The instant description refers to both FIGS. 1 and 2. The main chassis 4 is divided into two main sections including an upper optics section 10 and a lower vacuum chamber section 12. The upper optics section 10 includes scanner components 14 which include the endpoints of fiber optics carrying power from laser engine 6 and scanning optics. Separating upper optics section 10 from the lower vacuum chamber section 12 are transparent windows 16. Transparent windows 16 allow optical power to pass from scanner components 14 to the lower vacuum chamber 12. The transparent windows 16 protect the scanner components 14 from vapors generated in lower vacuum chamber 12 as metal powder is melted.

[0031] The upper optics section 10 is configured for calibration and servicing of the scanner components 14. The upper optics section 0 is configured to shuttle all or portions of scanner components 14 in a backward (+Y) direction so that they can be calibrated. The upper optics section 10 is also configured to shuttle the transparent windows 16 in a forward (-Y) direction so that they can be cleaned.

[0032] The lower vacuum chamber 12 contains modules for transporting powder and for storing and handling powder to be processed by the scanner components 14. The lower vacuum chamber 12 includes a build module 18, a storage module 20, a powder transport conduit 22, a vertical powder transport module 24, a fixed hopper (rail mounted for ease of removal and replacement but fixed during operation) 26, and a translating powder coater 28. The combination of the fixed hopper 26 and the translating powder coater 28 can be referred to as a powder layering apparatus (26 and 28).

[0033] The main chassis 4 can also include a port 31 for coupling an external source of metal powder to one or more of the modules for transporting and storing powder within the lower vacuum chamber 12. In some embodiments port 31 can be used to remove powder from the lower vacuum chamber 12 or to add additional powder to the powder transporting systems or storage module 20.

[0034] FIG. 3 depicts the modules for storing and transporting powder in more detail. The build module 18 includes lateral sides 30 including a left lateral side 30L and a right lateral side 30R. The storage module 20 includes lateral sides 32 including a left lateral side 32L and a right lateral side 32R. In the illustrated embodiment, the left lateral sides 30L and 32L are substantially coplanar and the right lateral sides 30R and 32R are substantially coplanar. Storage module 20 is at least partially below the build module 18 and, in the illustrated embodiment, modules 18 and 20 form an integral unit with common lateral sides 30 and 32.

[0035] At a lower end of the storage module 20 is a powder outlet 34 at which an inlet end 36 of the powder transport conduit 22 is positioned. In one embodiment the outlet 34 can include a valve. In the illustrative embodiment the powder transport conduit 22 is a vibratory chute 22 that slopes downwardly and laterally from inlet end 36 to an outlet end 38. The outlet end is coupled to a small powder tank 40 which is positioned at a lateral location. Rising upwardly from the powder tank 40 is the vertical powder transport module 24. The vertical powder transport module 24 is parallel to and in close proximity to but spaced apart from the left lateral sides 30L and 32L of the build module 18 and powder storage module 20 respectively. The vertical powder transport module 24 extends upwardly from a lower end 42 that is coupled to the powder tank 40 and to an upper end 44 that is above the fixed hopper 26. Extending laterally and downwardly from the upper end 44 is a laterally extending outlet 46 that is positioned to transfer powder down into an inlet 48 of the fixed hopper 26. The fixed hopper has an upper end 50 with inlet 48 and a lower dispensing end 52. The lower dispensing end 52 is positioned over a portion of the build module 18 that is proximate to the left lateral side 30L.

[0036] FIG. 4 is an isometric drawing depicting the build module 18 and powder storage module 20 in greater detail with a front panel removed. Build module 18 includes a vertically displaceable build platform 54 upon which layers of powder are to be dispensed and selectively melted. Build platform 54 is raised and lowered by a central piston 55. Displaceable build platform 54 moves vertically within a central build chamber 56. On the left and right lateral sides of central build chamber 56 are two overflow chamber portions 58L and 58R. Left overflow chamber portion 58L is between the left lateral side 30L and the central build chamber 56. Right overflow chamber portion 58R is between the central build chamber 56 and the right lateral side 30R. In one embodiment the overflow chamber 58 is one continuous chamber on all four sides of the central build chamber 56.

[0037] At least partially below (or directly below) the build module 18 is the

powder storage module 20. Powder storage module 20 defines an internal chamber volume 60 for storing powder. The powder storage module 20 includes sloped surfaces 62 that slope downwardly and inwardly toward the powder outlet 34. The sloped surfaces 62 define at least a portion of the internal chamber volume 62 that tapers downwardly to the powder outlet 34. Each of the overflow chambers 58 has a valve 59 that allows powder in each overflow chamber 58 to be released into the internal chamber volume 62 as desired.

[0038] FIGS. 5A-C are various views of the vertical powder transport module 24.

FIG. 5A is a side view of the entire vertical powder transport module 24 in isolation. FIG. 5B is a more detailed view of the lower end 42 of the vertical powder transport module 24. The vertical powder transport module 24 includes a outer vertical tube 64 with a helical screw 66. FIG. 5C illustrates a lower portion of the helical screw 66. The helical screw 66 includes a long internal portion 68 that extends through the vertical tube 64 and an external portion 70 that extends beyond the vertical tube 64. The long internal portion 68 has an outer diameter that is less than an inner diameter of the vertical tube 64. There is a clearance between the long internal portion 68 outer diameter and the inner diameter of the vertical tube 64 to minimize crushing and grinding of powder during vertical transport of the powder up through the vertical powder transport module 24. In the exemplary embodiment, the external portion 70 has an outer diameter that is greater than the outer diameter of the long internal portion 68 to improve efficiency of moving powder up into the vertical tube 64. [0039] In operation, the external portion 70 of helical screw 66 extends down into the powder tank 40. A motor rotates the helical screw 66 which in turn functions as an "Archimedes Screw" to transport powder from the powder tank 40 and up to the laterally extending outlet 46.

[0040] FIG. 6 depicts an upper portion of the build module 18, an upper portion of the vertical powder transport module 24, the fixed hopper 26, and the translating powder coater 28. As shown, the hopper 26 has an upper end 50 with an inlet 48 for receiving powder from the laterally extending outlet 46 of the vertical powder transport module 24. The upper end 50 of the hopper 26 has a sieve through which the powder passes before being released by the lower dispensing end 52. The lower dispensing end 52 extends from front to back (along Y) over the left overflow chamber portion 58L.

[0041] The translating powder coater 28 extends front to back (along Y) along the full span of the central build chamber 56 and translates back and forth along X to deposit each layer of powder. The translating powder coater 28 parks over the left overflow chamber portion 58L so as to be under the lower dispensing end 52 of hopper 26 when it requires a recharge of more powder. The powder coater 28 is capable of depositing layers of powder when moving in either the right (+X) or left (-X) direction.

[0042] FIGS. 7A-D are highly schematic figures illustrating a sequence of

operating the three dimensional printing system 2 to form a three dimensional article of manufacture 72. FIG. 7A depicts an initial state of the system 2 when the internal chamber volume 60 of the powder storage module 20 is initially full of metal powder.

[0043] FIG. 7B depicts the beginning of operation. Powder is transported out of the internal chamber volume 60, up the vertical powder transport module 24, and to the hopper 26. The hopper 26 has dispensed powder into the powder coater 28. Powder coater 28 has been dispensing layers of metal powder that are melted and fused by scanner components 14. In the process of dispensing layers of powder, the powder coater 28 levels each layer, with excess powder falling into the overflow chamber portions 58L and 58R.

[0044] FIG. 7C depicts continued operation and FIG. 7D depicts completed

operation. In the depicted completion, the internal chamber volume 60 is completely or nearly empty, the overflow chamber portions 58L and 58R are nearly full, and the three dimensional article of manufacture 72 is fully formed.

[0045] Although FIGS. 7A-D are highly schematic, they are suggestive of a

design alternative. In this alternative, a sloped surface 62 of the internal chamber volume 60 slopes down to an extension of the internal volume that provides a powder transport conduit 22 coupled to the a vertical powder transport module 24 at a lateral location which defines a powder tank 40.

[0046] The overall geometry of powder flow illustrated in this system 2 is (1)

laterally from below the powder storage module 20 to a left lateral side, (2) vertically up along the left lateral sides (30L and 32L), (3) laterally and

downwardly into the hopper 26, (4) downwardly into the powder coater 28, and then laterally from the powder coater 28 over the build platform 54. In an alternative embodiment, the powder flow could be to a right lateral side, vertically up along the right lateral side (30R and 32R), and to a fixed hopper that is above the right lateral side 30R of the build module 30. Then the powder coater 28 would receive powder from the hopper 26 while being parked over the right overflow chamber 58R.

[0047] In other embodiments, the powder coater 28 can move from front to back (+/- Y directions). For such an implementation, certain powder transport features such as the vertical powder transport module 24 and the lower dispensing end of the hopper 26 can be located at the back or front of the build chamber 56. [0048] FIG. 8 is an isometric schematic illustration of an exemplary embodiment of the modules for storing and transporting powder. The embodiment of FIG. 3 is an alternative to the more preferred embodiment of FIG. 8. In comparing elements, like elements generally indicate like functions, but the specific implementations may be different. Improvements in the FIG. 8 embodiment include a horizontal powder transport conduit 22 that spatially allows for a larger capacity storage module 20 for the same overall physical size of the lower vacuum chamber 12.

[0049] The powder transport unit 22 includes a motorized and rotating helical screw 74 that enables a horizontal transport of powder from a lower portion 76 of the storage module 20 to the powder tank 40. Helical screw 74 is similar to the helical screw 66. Thus, helical screw transportation moves powder from the lower portion 76 of the storage module 20 to the hopper 26. The helical screw transport is driven by motors 78 and 80 that rotate helical screws 74 and 66 respectively.

[0050] The specific embodiments and applications thereof described above are for illustrative purposes only and do not preclude modifications and variations encompassed by the scope of the following claims.