MOLTEN MATERIAL INTERFACES FOR MAGNETOHYDRODYNAMIC METAL MANUFACTURING

• US 20170252829A1
• Filed: 03/06/2017
• Published: 09/07/2017
• Est. Priority Date: 03/03/2016
• Status: Active Grant

• Current Assignee: Desktop Metal, Inc.
• Original Assignee: Desktop Metal, Inc.
• Inventors: Sachs, Emanuel Michael
• Granted Patent: US 10,639,718 B2
• Time in Patent Office: Days
• CPC Class Codes: B05B 5/025 Discharge apparatus, e.g. electrostatic spray guns
• CPC Class Codes: B22F 10/00 Additive manufacturing of workpieces or articles from metallic powder apparatus or devices therefor B22F12/00
• CPC Class Codes: B22F 10/22 Direct deposition of molten metal
• CPC Class Codes: B22F 10/32 of the atmosphere, e.g. composition or pressure in a building chamber
• CPC Class Codes: B22F 10/38 to achieve specific product aspects, e.g. surface smoothness, density, porosity or hollow structures
• CPC Class Codes: B22F 12/10 Auxiliary heating means
• CPC Class Codes: B22F 12/17 to heat the build chamber or platform
• CPC Class Codes: B22F 12/20 Cooling means
• CPC Class Codes: B22F 12/53 Nozzles
• CPC Class Codes: B22F 12/70 Gas flow means
• CPC Class Codes: B22F 12/90 Means for process control, e.g. cameras or sensors
• CPC Class Codes: B22F 2009/0892 casting nozzle; controlling metal stream in or after the casting nozzle
• CPC Class Codes: B22F 2202/06 Use of electric fields
• CPC Class Codes: B22F 2203/03 for feed-back
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/003 Apparatus, e.g. furnaces in general F27B
• CPC Class Codes: B22F 3/115 by spraying molten metal, i.e. spray sintering, spray casting
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes
• CPC Class Codes: B41J 2/14 : Structure thereof only for on-demand ink jet heads
• CPC Class Codes: B41J 2002/041 : Electromagnetic transducer
• CPC Class Codes: B41J 2202/04 : Heads using conductive ink
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

Devices, systems, and methods are directed to applying magnetohydrodynamic forces to liquid metal to eject liquid metal from a nozzle along a controlled pattern, such as a controlled three-dimensional pattern as part of additive manufacturing of an object. Electrodes used to deliver electric current across a firing chamber of the nozzle are formed of the same material as the liquid metal being ejected from the nozzle. For example, respective interfaces between the electrodes and the liquid metal can be molten material. Forming the electrodes and the liquid metal of the same material can facilitate, for example, ejecting liquid metals having high melt temperatures.

Claims

1. A method of manufacturing, the method comprising:

providing a liquid metal in a firing chamber at least partially defined by electrodes, the firing chamber in fluid communication with a discharge region defined by a housing supporting the electrodes;

directing a magnetic field into the liquid metal in the firing chamber; and

delivering electric current from the electrodes into the liquid metal in the firing chamber in a direction intersecting the magnetic field in the firing chamber to eject the liquid metal from the discharge region to form an object, wherein the electrodes and the liquid metal are formed of the same material at a respective interface between each electrode and the liquid metal.

2. The method of claim 1, further comprising moving the discharge region in a controlled three-dimensional pattern, the discharge region in fluid communication with the firing chamber, wherein delivering the electric current from the electrodes into the liquid metal in the firing chamber is based on the position of the discharge region along the controlled three-dimensional pattern.

3. The method of claim 1, further comprising, away from the respective interface of each electrode and the liquid metal, cooling each electrode, the cooling forming a respective temperature gradient in each electrode.

4. The method of claim 3, wherein the temperature gradient in each electrode maintains the respective interface between the electrode and the liquid metal within respective recesses defined by the housing, each interface remaining in the respective recess as the liquid metal is ejected from the discharge region.

5. The method of claim 4, wherein each recess extends in a direction radial to a direction of travel of the liquid metal toward the discharge region.

6. The method of claim 4, wherein cooling each electrode includes forced convection cooling of each electrode along a portion of each electrode away from the respective interface with the liquid metal.

7. The method of claim 6, wherein forced convection cooling of each electrode includes adjusting a rate of a cooling fluid based at least in part on a rate of liquid metal ejected from the discharge region.

8. The method of claim 1, wherein providing the liquid metal in the firing chamber includes directing the liquid metal from an inlet region defined by the housing to the firing chamber, the direction of travel of the liquid metal from the inlet region to the firing chamber intersecting the magnetic field and the electric current in the firing chamber.

9. The method of claim 8, wherein an axial length of the firing chamber is more than half of an axial length from the inlet region to the discharge region.

10. The method of claim 8, wherein the axial length from the inlet region to the discharge region is greater than about 2 mm and less than about 2 cm.

11. A system for jetting liquid metal, the system comprising:

electrodes defining at least a portion of a firing chamber, an electric current conductable into liquid metal in the firing chamber between the electrodes;

one or more magnets disposed relative to the electrodes with a magnetic field of the magnet extending through the firing chamber and intersecting the electric current in the firing chamber; and

a housing defining at least one portion of a fluid chamber, the fluid chamber having an inlet region, a discharge region, and recesses, wherein the electrodes are disposed in the recesses such that the firing chamber is within the fluid chamber between the inlet region and the discharge region and a maximum radial dimension of the firing chamber is greater than a maximum radial dimension a portion of the fluid chamber adjacent to the firing chamber.

12. The system of claim 11, further comprising a metal supply movable into the fluid chamber, the metal supply and the electrodes formed of the same material.

13. The system of claim 12, further comprising a heat source in thermal communication with the metal supply in or adjacent to the fluid chamber to form liquid metal movable into the firing chamber.

14. The system of claim 11, wherein the housing has a higher melting temperature than the material of the electrodes.

15. The system of claim 11, wherein at least one portion of each electrode extends outside of the housing in a direction away from the firing chamber.

16. The system of claim 11, further comprising a heat sink coupled to at least one portion of each electrode away from the firing chamber.

17. The system of claim 16, wherein the heat sink includes a fluid movable away from the at least one portion of each electrode to cool at the least one portion of each electrode.

18. The system of claim 11, wherein the firing chamber has an axial length greater than 50 percent of an axial length of the fluid chamber.

19. The system of claim 11, wherein the axial length of the fluid chamber is greater than about 2 mm and less than about 2 cm.