Managing powder mobility in binder jetting for additive manufacturing

Patent metadata

Field	Value
Publication number	US-10486363-B2
Application number	US-201916243966-A
Country	US
Kind code	B2
Filing date	Jan 9, 2019
Priority date	Jan 9, 2018
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

Devices, systems, and methods are directed to the use of vapor phase change in binder jetting processes for forming three-dimensional objects. In general, a vapor of a first fluid may be directed to a layer of a powder spread across a build volume. The vapor may condense to reduce mobility of the particles of the powder of the layer. For example, the condensing vapor may reduce the likelihood of particle ejection from the layer and, thus, may reduce the likelihood of clogging or otherwise degrading a printhead used to jet a second fluid (e.g., a binder) to the layer. Further, or instead, the condensing vapor may increase the density of the powder in the layer which, when repeated over a plurality of layers forming a three-dimensional object, may reduce the likelihood of slumping of the part during sintering.

First claim

What is claimed is:

1. A method for managing powder mobility in binder jet additive manufacturing, the method comprising:
spreading a layer of a powder across a build volume, the powder having a mobility for particles of the powder as the layer of the powder is spread across the build volume;
directing a first fluid in a vapor phase toward the layer;
condensing the first fluid from the vapor phase to a liquid phase to reduce the mobility of the particles of the powder;
delivering a second fluid along the layer in a controlled two-dimensional pattern associated with a portion of a three-dimensional object to be formed within the layer; and
for each layer of a plurality of layers, repeating the steps of spreading a respective layer of the powder, directing the first fluid in the vapor phase toward the respective layer, condensing the first fluid from the vapor phase to the liquid phase to reduce mobility of the particles of the powder along the respective layer, and delivering the second fluid along the respective layer, wherein at least the second fluid operates to bind at least some of the powder in the plurality of layers to define a three-dimensional object in the build volume.

2. The method of claim 1 , wherein, for each layer, condensing the first fluid from the vapor phase to the liquid phase precedes delivering the second fluid to the respective layer.

3. The method of claim 1 , wherein at least a portion of each layer of the powder is at a temperature less than a dew point of the first fluid in a gaseous environment above the respective layer.

4. The method of claim 1 , wherein the first fluid includes one or more of water, acetone, toluene, methyl ethyl ketone, ethanol, isopropyl alcohol, and n-butyl acetate.

5. The method of claim 1 , wherein directing the first fluid in the vapor phase to each layer of the powder includes issuing the first fluid in the vapor phase from an outlet section defined by an evaporator over the respective layer.

6. The method of claim 5 , further comprising moving the evaporator and respective layer relative to one another as the first fluid in the vapor phase issues from the outlet section toward the given layer.

7. The method of claim 1 , wherein directing the first fluid in the vapor phase to each layer of the powder includes delivering the first fluid in the vapor phase along a span of at least one dimension of the respective layer.

8. The method of claim 1 , wherein a void space is defined between particles of the powder in the plurality of layers and the first fluid in the liquid phase fills greater than about 0.1 percent of the void space and less than about 10 percent of the void space.

9. The method of claim 1 , wherein the first fluid in the vapor phase is at a temperature less than a boiling point of the first fluid.

10. The method of claim 1 , wherein the first fluid in the vapor phase is at a temperature greater than or equal to a boiling point of the first fluid.

11. The method of claim 1 , wherein directing the first fluid in the vapor phase to each layer of the powder includes forming a mixture of the vapor phase of the first fluid with a carrier gas, the carrier gas different from the vapor phase of the first fluid, and delivering the mixture toward the respective layer.

12. The method of claim 11 , wherein forming the mixture of the vapor phase of the first fluid with the carrier gas includes sparging the carrier gas through the first fluid.

13. The method of claim 11 , wherein the carrier gas includes one or more of nitrogen, argon, or air.

14. The method of claim 1 , wherein directing the first fluid in the vapor phase to each layer of the powder includes forming liquid droplets of the first fluid and vaporizing the liquid droplets of the first fluid to form the first fluid in the vapor phase.

15. The method of claim 14 , wherein forming the liquid droplets of the first fluid includes atomizing a liquid phase of the first fluid.

16. The method of claim 15 , wherein atomizing the liquid phase of the first fluid includes one or more of ultrasonic atomization, hydraulic atomization, or gas atomization.

17. The method of claim 14 , wherein the liquid droplets have an average size of greater than about 5 microns and less than about 100 microns.

18. The method of claim 14 , wherein directing the first fluid in the vapor phase to each layer of the powder further includes dispersing the liquid droplets in a distribution gas, and vaporizing the liquid droplets of the first fluid in the distribution gas to form a mixture of the first fluid in the vapor phase and the distribution gas.

19. A system for controlling powder mobility in binder jet additive manufacturing, comprising:
a print box defining at least a portion of a build volume;
a spreader above the print box, the spreader and the print box movable relative to one another to spread a layer of a powder along the build volume;
a printhead defining at least one ejection orifice directed toward the print box; and
an evaporator including a housing and a heater, the housing defining an inlet section, an outlet section, and a flow path extending therebetween, and the heater in thermal communication with the flow path, wherein the spreader, the outlet section, the at least one ejection orifice, and the print box are movable in coordination with one another such that a vapor heated along the flow path by the heater is issuable from the outlet section of the evaporator to the layer of the powder in advance of a liquid delivered from the at least one ejection orifice of the printhead to the layer of the powder.

20. The system of claim 19 , wherein the inlet section has a first open area, the outlet section has a second open area, and a ratio of the second open area to the first open area is greater than about 10:1 and less than about 5,000:1.

21. The system of claim 19 , wherein the print box is stationary and the spreader, the printhead, and the outlet section of the evaporator are movable in coordination with one another over the print box.

22. The system of claim 19 , wherein at least a portion of the flow path between the inlet section and the outlet section is nonlinear.

23. The system of claim 19 , wherein the evaporator further includes an atomizer disposed along the inlet section and in fluid communication with the outlet section via the flow path.

24. The system of claim 23 , wherein the atomizer is one or more of an ultrasonic atomizer, a hydraulic atomizer, or a gas atomizer.

25. The system of claim 23 , wherein the atomizer further comprises a gate selectively movable relative to the flow path to control fluid flow through the outlet section.

26. The system of claim 19 , wherein the evaporator further comprises a humidity probe positioned to measure humidity of a fluid issuing from the outlet section of the evaporator.

27. The system of claim 19 , wherein the outlet section includes a slit spanning at least one dimension of the build volume as the outlet section is over the print box.

28. The system of claim 19 , further comprising a controller in electrical communication with the spreader, the printhead, and the evaporator, the controller including one or more processors and a non-transitory, computer-readable storage medium having stored thereon computer executable instructions for causing one or more processors to
move the spreader and the print box rela

Assignees

• Desktop Metal Inc

Inventors

• Sachs Emanuel Michael
• Hudelson George
• Hoisington Paul A
• Renner Christopher Benjamin
• Vaillancourt Keith Roy
• Moynihan Edward Russell

Classifications

• B28B1/001

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