GE has found a way to automatically refill powder hoppers on 3D printers.
A powder bed 3D printer can have hours of work remaining and still run short of powder. That’s the problem being solved through a European patent application from General Electric Company, EP4834569A2. It proposes a material supply configuration that refills the printer’s powder delivery system without opening the 3D printer at all.
Consider a typical powder bed 3D printer: A supply piston raises a small amount of powder above the working surface, where a recoater pushes and spreads it across the adjacent build area. The build platform drops slightly, and the process repeats. Eventually, the supply compartment needs replenishing, but all of this takes place inside the build chamber, a controlled environment.
In the patent GE’s proposed system connects that powder compartment to a larger supply.
Powder starts its journey in a reservoir and is carried with gas through a tube to a conveyance hopper. A filter separates the powder from the gas, allowing the powder to collect. From there it drops into a smaller dosing hopper, which feeds an inclined chute leading to the supply compartment beside the build area.
Then the piston does something quite interesting.
When the piston moves down, its upper surface drops below the chute opening in the supply compartment’s sidewall. Powder can flow in under gravity. When the piston rises, it lifts the accumulated powder toward the working surface while closing off the opening with its own sidewall.
The piston is therefore doing two jobs: delivering powder for recoating and controlling when the supply compartment can refill. The filing also describes optional valves and sensors for more control and tuning.
There’s another opening connected to an excess powder return. The recoater can push unused powder across a sieve into this return, where it can flow back into the supply compartment when the piston lowers again. The sieve is intended to grab larger bits before they re-enter the feed.
A camera or other sensor could identify contaminated or unwanted material. The controller would open a trapdoor in the working surface, allowing the recoater to sweep the offending material into a separate collection bin rather than spreading it across the next layer.
So, in all the machine would replenish powder, recover some unused material and remove suspicious material without requiring an operator to intervene at any point in the process.
GE proposes level sensors to trigger replenishment from the main reservoir, vibrators to encourage stubborn powder to flow, and gas handling equipment that could help maintain a controlled atmosphere. One piston configuration intends to move between its operating positions in less than two seconds. That’s quick.
I suspect the hardest part of this proposal would be the powder flow. Fine powders don’t always flow as easily as liquids, particularly through chutes, curves, sieves, etc. The patent’s many provisions for vibration, purge gas and cleaning suggest GE has probably considered those complications, though.
If implemented (and that’s likely given that GE has patented it), we could see machines themselves handle routine powder refills inside a closed enclosure, while the operator merely has to keep the reservoir topped up.
Via Espacenet
