Molten metal jetting for additive manufacturing

Patent metadata

Field	Value
Publication number	US-2017087632-A1
Application number	US-201615275849-A
Country	US
Kind code	A1
Filing date	Sep 26, 2016
Priority date	Sep 24, 2015
Publication date	Mar 30, 2017
Grant date	—

Abstract

In molten metal jetting, where droplets of metal are jetted to 3D print a part, each layer may be traversed each successive layer with a normalizing grinding wheel or other leveling device such as a layer to level each successive layer, and/or the melt reservoir or printing chamber may be filled with an anoxic gas mix to prevent oxidation.

First claim

What is claimed is:

1 . A method of molten metal jetting for additive manufacturing, comprising:
feeding a wire of solid metal material along a material feed path; melting the solid metal material to molten metal in a melt reservoir; pressurizing the melt reservoir to a predetermined pressure insufficient to eject droplets; generating a pressure oscillation in the molten metal in the melt reservoir to force at least one of jetting of the molten metal through a nozzle and formation of molten metal droplets by surface tension at the nozzle; driving the nozzle to relatively move with respect to a build plate in at least three degrees of freedom; forming successive layers of solidified metal by accumulation of the molten metal droplets impacting a previously deposited layer of solidified metal and cooling thereon; and traversing each successive layer with a normalizing grinding wheel to level each successive layer.

2 . The method according to claim 1 , wherein the normalizing grinding wheel is driven to traverse with its rotating axis entirely within a plane parallel to a plane in which a layer is formed.

3 . The method according to claim 1 , wherein the normalizing grinding wheel is connected to and moved with the nozzle.

4 . The method according to claim 1 , wherein the normalizing grinding wheel removes sufficient material to shave both peaks and valleys in an irregular surface.

5 . The method according to claim 4 , wherein the normalizing grinding wheel removes 10-80% of the deposited solidified metal height.

6 . The method according to claim 1 , wherein a contact surface consisting of a line along the width of the grinding wheel is traversed over an area of no more than 125% of the area of the previously deposited solidified metal layer.

7 . The method according to claim 1 , wherein one of an inert gas supply and an inert gas generator supplies an inert gas to shield the molten metal from oxidation.

8 . The method according to claim 7 , wherein the supply of inert gas is shared among at least two of the following:
a. an inert gas feed to maintain an oxidation-free environment in the melt reservoir, b. an inert gas feed to maintain an oxidation-free environment in a print chamber, and c. an inert gas feed to maintain an oxidation shield extending between the nozzle and the build plate and about the molten droplets as they are jetted.

9 . A method of molten metal jetting for additive manufacturing, comprising:
feeding a wire of solid metal material along a material feed path; melting the solid metal material to molten metal in a melt reservoir; pressurizing the molten metal in the melt reservoir to a predetermined pressure insufficient to eject droplets; supplying inert gas to shield the molten metal from oxidation from one of an inert gas supply and an inert gas generator; generating a pressure oscillation in the molten metal in the melt reservoir to force at least one of jetting of molten metal through a nozzle and formation of molten metal droplets by surface tension at the nozzle; driving the nozzle to relatively move with respect to a build plate in at least three degrees of freedom; and forming successive layers of solidified metal by accumulation of the molten metal droplets impacting a previously deposited layer of solidified metal and cooling thereon.

10 . The method according to claim 9 , further comprising:
loading the melt reservoir by introducing an initial charge of unmelted material to the melt reservoir; feeding inert gas into a print head; introducing an oxide removal agent; heating the print head to activate the oxide removal agent; and purging metal and oxidized metal from the print head.

11 . The method according to claim 10 , wherein purging metal and oxidized metal from the print head includes purging metal and oxidized metal from the print head by feeding additional oxide removal agent, metal, and inert gas into the nozzle.

12 . The method according to claim 9 , further comprising:
before removing a part, associated with a locked/unlocked state of an electronic interlock on a sealed door, purging an anoxic chamber by at least one of removing oxygen from and flowing inert gas into the anoxic chamber.

13 . The method according to claim 9 , further comprising:
before removing a part, associated with a locked/unlocked state of an electronic interlock on a sealed door, purging the melt reservoir by at least one of removing oxygen from and flowing inert gas into the melt reservoir.

14 . The method according to claim 9 , further comprising:
before beginning printing, associated with a locked/unlocked state of an electronic interlock on a sealed door, purging an anoxic chamber by at least one of removing oxygen from and flowing inert gas into the anoxic chamber.

15 . The method according to claim 9 , further comprising:
before beginning printing, associated with a locked/unlocked state of an electronic interlock on a sealed door, purging the melt reservoir by at least one of removing oxygen from and flowing inert gas into the melt reservoir.

16 . The method according to claim 9 , further comprising:
before beginning printing, associated with a locked/unlocked state of an electronic interlock on a sealed door, purging the melt reservoir by flowing anoxic gas through the melt reservoir in a gaseous volume in excess of a melt reservoir volume.

Assignees

• Markforged Inc

Inventors

• Mark Gregory Thomas

Classifications

• B22F10/22

  Direct deposition of molten metal · CPC title

• B22F12/53

  Nozzles · CPC title

• B22F12/55

  Two or more means for feeding material · CPC title

• B22F12/20

  Cooling means · CPC title

• B22F10/43

  characterised by material · CPC title