Magnetohydrodynamic deposition of metal in manufacturing

Patent metadata

Field	Value
Publication number	US-2017252821-A1
Application number	US-201715451260-A
Country	US
Kind code	A1
Filing date	Mar 6, 2017
Priority date	Mar 3, 2016
Publication date	Sep 7, 2017
Grant date	—

Abstract

Devices, systems, and methods are directed to applying magnetohydrodynamic forces to liquid metal to eject liquid metal along a controlled pattern, such as a controlled three-dimensional pattern as part of additive manufacturing of an object. The magnetohydrodynamic force can be pulsed to eject droplets of the liquid metal to provide control over accuracy of the object being fabricated. The pulsations can be applied in fluid chambers having high resonance frequencies such that droplet ejection can be effectively controlled over a wide range of frequencies, including high frequencies suitable for liquid metal ejection at rates suitable for commercially viable three-dimensional fabrication.

First claim

What is claimed is:

1 . A nozzle for jetting liquid metal, the nozzle comprising:
a housing defining at least a portion of a 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, wherein electric current is conductible from the electrodes into the firing chamber at least at a point substantially adjacent to a discharge orifice of the discharge region, and the electric current intersects the magnetic field in the firing chamber at the point substantially adjacent to the discharge orifice to eject liquid metal from the discharge orifice.

2 . The nozzle of claim 1 , wherein a volume of the fluid chamber between the firing chamber and the discharge orifice is less than about ten percent of a total volume of the fluid chamber.

3 . The nozzle of claim 1 , wherein the volume of the firing chamber is greater than about 50 percent of the total volume of the fluid chamber.

4 . The nozzle of claim 1 , wherein the fluid chamber has an axial length of greater than about 2 mm and less than about 2 cm.

5 . The nozzle of claim 1 , wherein at least one of the electrodes is integrally formed with a portion of the housing defining at least a portion of the fluid chamber such that the at least one electrode and the portion of the housing defining at least one of the fluid chamber are formed of the same material.

6 . The nozzle of claim 5 , wherein at least one of the electrodes is integrally formed with a portion of the housing defining at least the discharge region of the fluid chamber such that the at least one electrode and the portion of the housing defining the discharge region are formed of the same material.

7 . The nozzle of claim 1 , wherein the housing is a rod of electrically conductive material and electric current is conductible between the electrodes along an axis parallel to an axial dimension of the rod.

8 . The nozzle of claim 1 , wherein the firing chamber includes a substantially rectangular cross-section in a plane perpendicular to a direction of travel of liquid metal from the inlet region toward the discharge region, and electric current from the electrodes is conductible into liquid metal along the substantially rectangular cross-section.

9 . The nozzle of claim 1 , further comprising a filter disposed along the fluid chamber and spaced apart from the discharge region.

10 . The nozzle of claim 1 , wherein at least one of the electrodes is formed of tantalum, niobium, or a combination thereof.

11 . An additive manufacturing system, the system comprising:
a nozzle including a housing, one or more magnets, and electrodes, the nozzle defining a fluid chamber having an inlet region and a discharge region, the one or more magnets directing a magnetic field through the housing, and the electrodes defining at least a portion of a firing chamber in the fluid chamber between the inlet region and the discharge region, wherein electric current is conductible from the electrodes such that the electric current intersects the magnetic field in the firing chamber at a point substantially adjacent to a discharge orifice of the discharge region; a robotic system mechanically coupled to the nozzle; an electrical power source in electrical communication with the electrodes; and a controller in electrical communication with the robotic system and the electrical power source, the controller configured to
move the robotic system to position the discharge region of the nozzle in a controlled three-dimensional pattern, and
based on the position of the discharge region along the controlled three-dimensional pattern, to actuate the power source to deliver pulsed current to the electrodes to eject liquid metal from the discharge region to form a three-dimensional object.

12 . The system of claim 11 , wherein the frequency of the pulsed current is less than about 5 kHz at a maximum speed of movement of the discharge region.

13 . The system of claim 11 , wherein the pulsed current has a frequency based on speed of movement of the nozzle.

14 . The system of claim 11 , wherein the pulsed current has a frequency based on one or more features of the three-dimensional pattern.

15 . A method of additive manufacturing, the method comprising:
providing a liquid metal in a fluid chamber at least partially defined by a housing, the fluid chamber having an inlet region and a discharge region; directing a magnetic field through the housing; moving the discharge region in a controlled three-dimensional pattern; and based on the position of the discharge region along the controlled three-dimensional pattern, conducting a pulsed electric current into the liquid metal in a firing chamber within the fluid chamber between the inlet region and the discharge region, wherein the pulsed electric current is at a frequency less than a resonant frequency of the liquid metal in the fluid chamber, and the pulsed electric current is in a direction intersecting the magnetic field in the firing chamber such that pulsation of electric current ejects liquid metal from the discharge region to form a three-dimensional object.

16 . The method of claim 15 , wherein the pulsed electric current is conducted into liquid metal in the firing chamber substantially adjacent to the discharge region.

17 . The method of claim 15 , wherein the resonant frequency of the liquid metal in the fluid chamber is greater than about 10 kHz.

18 . The method of claim 15 , wherein the volume of the firing chamber is greater than about 50 percent of the volume of the fluid chamber.

19 . The method of claim 15 , wherein electrical resistivity of the liquid metal is substantially similar to electrical resistivity of material defining the firing chamber.

Assignees

• Desktop Metal Inc

Inventors

• Sachs Emanuel Michael
• Gibson Mark Gardner
• Hoisington Paul A
• Fontana Richard Remo

Classifications

• B22F2999/00

  Aspects linked to processes or compositions used in powder metallurgy · CPC title

• B33Y30/00

  Apparatus for additive manufacturing; Details thereof or accessories therefor · CPC title

• B33Y50/02

  for controlling or regulating additive manufacturing processes · CPC title

• B33Y10/00

  Processes of additive manufacturing · CPC title

• B22F3/115 Primary

  by spraying molten metal, i.e. spray sintering, spray casting · CPC title