Selective laser sintering powder recycle system

• US 7,887,316 B2
• Filed: 02/27/2009
• Issued: 02/15/2011
• Est. Priority Date: 03/09/2005
• Status: Active Grant

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Inventors: Cox, Brian David
• Primary Examiner(s): EWALD, MARIA VERONICA
• Application Number:
  US12/394,573
• Publication Number:
  US 20090169664A1
• Time in Patent Office: 718 Days
• Field of Search: 425/174.4, 425/375, 425/215, 425/217, 264/113, 264/308, 264/401, 264/497
• US Class Current: 425/215
• CPC Class Codes: B01F 23/69 Mixing systems, i.e. flow charts or diagrams; Arrangements, e.g. comprising controlling means
• CPC Class Codes: B01F 25/50 Circulation mixers, e.g. wherein at least part of the mixture is discharged from and reintroduced into a receptacle
• CPC Class Codes: B01F 25/83 with receptacles provided with fixed guiding elements therein, e.g. baffles; Cross-mixers comprising crossing channels for guiding the falling particles
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/322 of the gas flow, e.g. rate or direction
• CPC Class Codes: B22F 10/73 of powder
• CPC Class Codes: B22F 12/52 Hoppers
• CPC Class Codes: B22F 12/55 Two or more means for feeding material
• CPC Class Codes: B22F 12/63 Rollers
• CPC Class Codes: B29B 17/0005 Direct recuperation and re-use of scrap material during moulding operation, i.e. feed-back of used material
• CPC Class Codes: B29C 64/153 using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• CPC Class Codes: B29C 64/357 Recycling
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 40/00 Auxiliary operations or equipment, e.g. for material handling
• CPC Class Codes: Y02P 10/20 Recycling
• CPC Class Codes: Y02P 10/25 Process efficiency
• CPC Class Codes: Y02W 30/62 Plastics recycling; Rubber recycling

Abstract

A method and apparatus for forming three-dimensional objects by laser sintering that includes the use of dense phase pneumatic conveying to internally recycle overflow powder, and to thoroughly blend overflow, recovered and virgin powder to provide a consistent powder feed mix to a laser sintering machine. Overflow powder from the laser sintering machine is recovered and recycled back into the laser sintering machine for reuse. The approach results in a compact and reliable powder recycle system with complete blending and minimum attrition to the handled powder.

Claims

1. A laser sintering powder recycle system comprising:

(a) a laser sintering machine in which a layerwise build process is performed to produce at least one three-dimensional object, the laser sintering machine comprising a dense phase conveying device for transferring an amount of overflow powder from a receiving device within the laser sintering system directly to a powder feed hopper within the laser sintering system, wherein the overflow powder is kept within the laser sintering system;

(b) a breakout station for receiving a part cake that includes the three-dimensional object from the laser sintering machine and an amount of unfused powder surrounding the three-dimensional object, the breakout station comprising a separation device for separating the unfused powder into recovered powder and spent powder and further comprising a dense phase conveying device for transferring the recovered powder from the breakout station to the powder feed hopper of the laser sintering system;

(c) a virgin powder supply from which virgin powder is transferred to the powder feed hopper of the laser sintering system; and

(d) a powder processing unit that comprises;

(i) a recovered powder inlet for receiving the recovered powder from the breakout station;

(ii) a virgin powder inlet for receiving the virgin powder from the virgin powder supply;

(iii) a blender vessel for blending and storing combinations of recovered powder and virgin powder; and

(iv) a dense phase conveying device for transferring the combined recovered and virgin powder from the blender vessel to the powder feed hopper of the laser sintering machine.

2. A system according to claim 1 wherein the virgin powder supply is in flow communication with a dense phase conveying device for transferring the virgin powder from the virgin powder supply to the powder processing unit.

3. A system according to claim 1 wherein the powder processing unit comprises a virgin powder storage vessel into which virgin powder is transferred from the virgin powder supply.

4. A system according to claim 3 wherein the virgin powder storage vessel comprises a cone in cone blender device.

5. A system according to claim 3 wherein a dense phase conveying device transfers the virgin powder in the virgin powder storage vessel to the blender vessel.

6. A system according to claim 1 wherein the powder processing unit comprises a recovered powder storage vessel that stores and blends quantities of recovered powder.

7. A system according to claim 6 wherein the recovered powder storage vessel comprises a weighing device to accurately weigh the powder contained in the vessel.

8. A system according to claim 1 wherein the blender vessel comprises a weighing device to accurately weigh the powder contained in the vessel.

9. A breakout station for use with a laser sintering machine in which a layerwise build process is performed to produce at least one three-dimensional object from powder deposited by a powder feed hopper, the breakout station comprising:

(a) a worktable for receiving a part cake that includes the three-dimensional object from the laser sintering machine and an amount of unfused powder surrounding the three-dimensional object;

(b) a separation device for separating the unfused powder into recovered powder and spent powder; and

(c) a dense phase conveying system for transferring the recovered powder from the separation device to powder feed hopper,

wherein the breakout station further comprises a screw feeder to feed the unfused powder from the worktable to the separation device and wherein the dense phase conveying system is in flow communication with a powder processing unit that blends the recovered powder with a virgin powder before transferring the blended powder to the powder feed hopper.