Magnetohydrodynamic deposition rate control for metal manufacturing

Patent metadata

Field	Value
Publication number	US-2017252827-A1
Application number	US-201715451308-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. An electric current delivered to produce the magnetohydrodynamic forces can be controlled between a pulsed electric current and a direct electric current to change the rate of liquid metal ejection from a nozzle. For example, the electric current can be switched between a pulsed electric current and a direct electric current based at least in part on a position of the nozzle along the controlled pattern, providing accuracy of liquid metal deposition along portions of the pattern having more detail and providing speed of liquid metal deposition along portions of the pattern having less detail.

First claim

What is claimed is:

1 . 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 pattern; and delivering electric current between electrodes defining at least a portion of a firing chamber within the fluid chamber between the inlet region and the discharge region, the electric current intersecting the magnetic field in the liquid metal in the firing chamber to eject liquid metal from the discharge region; and based on the position of the discharge region along the controlled pattern, controlling the electric current between pulsed current and direct current to form an object.

2 . The method of claim 1 , wherein the controlled pattern is a three-dimensional pattern and the object is a three-dimensional object.

3 . The method of claim 1 , wherein the electric current is controlled to be pulsed current along a boundary of the object being formed.

4 . The method of claim 1 , wherein the electric current is controlled to be direct current as the discharge region moves along an excursion within a boundary of the object being formed.

5 . The method of claim 1 , wherein a frequency of the pulsed current is less than a resonance frequency of the liquid metal in the fluid chamber.

6 . The method of claim 1 , wherein a frequency of the pulsed current is based on speed of movement of the discharge region.

7 . The method of claim 1 , wherein a frequency of the pulsed current is based on distance from an edge of the controlled pattern.

8 . The method of claim 1 , wherein a frequency of the pulsed current is less than about 5 kHz at a maximum speed of movement of the discharge region.

9 . The method of claim 1 , wherein switching from the pulsed current to the direct current increases a mass flow rate of liquid metal ejected from the discharge region.

10 . A computer program product comprising non-transitory computer executable code embodied in a non-transitory computer readable medium that, when executing on one or more processors, performs the steps of:
moving a discharge region of a nozzle in a controlled pattern; delivering electric current between electrodes defining at least a portion of a firing chamber in fluid communication with the discharge region, the electric current intersecting a magnetic field in a liquid metal in the firing chamber to eject the liquid metal from the discharge region; and based on the position of the discharge region along the controlled pattern, controlling electric current delivered into the liquid metal in the firing chamber, wherein the electric current is controlled between pulsed current and direct current to form an object.

11 . The computer program produce of claim 10 , wherein the electric current is controlled to be pulsed current along a boundary of the object being formed.

12 . The computer program produce of claim 10 , wherein the electric current is controlled to be direct current as the discharge region moves along an excursion within a boundary of the object being formed.

13 . The computer program produce of claim 10 , wherein a frequency of the pulsed current is based on speed of movement of the discharge region.

14 . The computer program produce of claim 10 , wherein a frequency of the pulsed current is based on distance from an edge of the controlled pattern.

15 . The computer program produce of claim 10 , wherein a frequency of the pulsed current is less than about 5 kHz at a maximum speed of movement of the discharge region.

16 . An additive manufacturing system, the system comprising:
a nozzle including a housing, a magnet, and electrodes, the housing defining at least a portion of a fluid chamber, the fluid chamber having an inlet region and a discharge region, the magnet disposed relative to the housing with a magnetic field of the magnet extending through the housing, and the electrodes defining at least a portion of a firing chamber within the fluid chamber between the inlet region and the discharge region, the electrodes positioned relative to the magnet such that electric current delivered between the electrodes intersects the magnetic field in the firing chamber; a robotic system mechanically coupled to the nozzle and movable to position the discharge region; an electrical power source in electrical communication with the electrodes of the nozzle; and a controller in electrical communication with the electrical power source, the controller configured to
move the robotic system to position the discharge region in a controlled pattern,
deliver electric current from the electrodes into a liquid metal in the firing chamber,
based on the position of the discharge region along the controlled pattern, control electric current delivered into liquid metal in the firing chamber, wherein the electric current is controlled between pulsed current and direct current to form an object.

17 . The system of claim 16 , wherein the electric current is controlled to be pulsed current along a boundary of the object being formed.

18 . The system of claim 16 , wherein the electric current is controlled to be direct current as the discharge region moves along an excursion within a boundary of the object being formed.

19 . The system of claim 16 , wherein a frequency of the pulsed current is based on speed of movement of the discharge region.

20 . The system of claim 16 , wherein a frequency of the pulsed current is based on distance from an edge of the controlled pattern.

Assignees

• Desktop Metal Inc

Inventors

• Sachs Emanuel Michael
• Fontana Richard Remo

Classifications

• B22F2999/00

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

• B22F3/115 Primary

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

• B33Y50/02

  for controlling or regulating additive manufacturing processes · CPC title

• B33Y30/00

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

• B33Y10/00

  Processes of additive manufacturing · CPC title