MATERIAL SUPPLY FOR MAGNETOHYDRODYNAMIC METAL MANUFACTURING

• US 20170252828A1
• 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, Gibson, Mark Gardner, Fontana, Richard Remo
• Granted Patent: US 10,603,718 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. A feeder system can provide a continuous or substantially continuous supply of a solid metal to the nozzle to facilitate a correspondingly continuous or substantially continuous process for ejecting liquid metal as part of a commercially viable manufacturing process.

Claims

1. A manufacturing system, the system comprising:

a nozzle including

a housing defining a fluid chamber, the fluid chamber having an inlet region and a discharge region,

one or more magnets disposed relative to the housing with a magnetic field of the magnet directed through the housing, and

electrodes defining at least a portion of a firing chamber within the fluid chamber between the inlet region and the discharge region, the electrodes arranged relative to the magnet such that electric current flowing between the electrodes intersects the magnetic field in the firing chamber to eject liquid metal from the discharge region; and

a robotic system coupled to the nozzle and movable to position the discharge region along a controlled pattern; and

a feeder system engageable with a metal wire, the feeder system actuatable to direct the metal wire into the fluid chamber, via the inlet region, as liquid metal is ejected from the discharge region along the controlled pattern to form an object.

2. The system of claim 1, wherein the feeder system includes a plurality of rollers engageable with the metal wire, the plurality of rollers rotatable to feed the metal wire into the fluid chamber.

3. The system of claim 1, further comprising a heater in thermal communication with the fluid chamber.

4. The system of claim 3, wherein the heater includes an induction heater.

5. The system of claim 1, wherein the feeder system is actuatable to direct the metal wire into the inlet region at a variable rate, the variable rate based at least in part upon a rate of liquid metal ejection from the discharge region.

6. The system of claim 1, further comprising a sensor directed toward the inlet region, the sensor configured to detect an interface between the metal wire and the liquid metal along a predetermined axial distance on each side of the inlet region, and the sensor in electrical communication with the feeder system to change a rate of movement of the metal wire into the inlet region based on a signal received from the sensor.

7. The system of claim 6, wherein the sensor is configured to detect a discontinuity between the metal wire and the liquid metal along the predetermined axial distance on each side of the inlet region.

8. The system of claim 6, wherein the predetermined axial distance on each side of the inlet region is substantially equal to one-half of a maximum dimension of the inlet region.

9. The system of claim 6, wherein the sensor includes one or more of machine vision and an optical break-beam sensor.

10. The system of claim 1, further comprising a wiper movable relative to the inlet region to remove debris adjacent to or within the inlet region.

11. The system of claim 1, further comprising a source of pressurized gas actuatable to disperse pressurized gas relative to the inlet region to remove debris adjacent to or within the inlet region.

12. The system of claim 11, wherein the source of pressurized gas is arranged to direct pressurized gas through the inlet region in a direction toward the discharge region.

13. A method of manufacturing, the method comprising:

directing a metal wire toward a fluid chamber at least partially defined by a housing, the fluid chamber having an inlet region and a discharge region;

melting a portion of the metal wire to a liquid metal, wherein an interface between the metal wire and the liquid metal is adjacent to the inlet region;

delivering the liquid metal from the fluid chamber to a firing chamber at least partially defined by electrodes, the firing chamber within the fluid chamber between the inlet region and the discharge region; and

applying a magnetohydrodynamic force to the liquid metal in the firing chamber, wherein the metal wire is directed into the fluid chamber at a rate sufficient to maintain continuous contact between the metal wire and the liquid metal at the interface as the liquid metal is ejected from the discharge region by the magnetohydrodynamic force.

14. The method of claim 13, wherein the interface is outside of the housing.

15. The method of claim 13, wherein the interface is within a predetermined axial distance on each side of the inlet region.

16. The method of claim 15, wherein the predetermined axial distance is about one-half of a maximum axial dimension of the inlet region.

17. The method of claim 13, further comprising mechanically removing debris in and adjacent to the inlet region.

18. The method of claim 17, wherein mechanically removing debris includes moving a wiper relative to the inlet region.

19. The method of claim 13, further comprising pneumatically removing debris in and adjacent to the inlet region.

20. The method of claim 19, wherein pneumatically removing debris includes directing pressurized gas through the inlet region in a direction toward the discharge region.

21. The method of claim 13, further comprising electrically removing debris in and adjacent to the inlet region, wherein electrically removing debris includes directing a pulse of electric current between the electrodes in a direction relative to a magnetic field to create, in the liquid metal, a magnetohydrodynamic force in a direction from the firing chamber toward the inlet region.