Method for selective laser sintering with layerwise cross-scanning

• US 5,155,324 A
• Filed: 11/09/1990
• Issued: 10/13/1992
• Est. Priority Date: 10/17/1986
• Status: Expired due to Fees

• Current Assignee: Carl R. Deckard, James F. Darrah, Joseph J. Beaman
• Original Assignee: Carl R. Deckard, James F. Darrah, Joseph J. Beaman
• Inventors: Beaman, Joseph J., Darrah, James F., Deckard, Carl R.
• Primary Examiner(s): ALBRITTON, CLARENCE
• Application Number:
  US07/611,025
• Time in Patent Office: 704 Days
• Field of Search: 219/121.63, 219/121.64, 219/121.6, 219/121.85, 219/121.65, 219/121.66, 219/121.8, 219/121.82
• US Class Current: 264/497
• CPC Class Codes: B05C 19/00 Apparatus specially adapted for applying particulate materials to surfaces
• CPC Class Codes: B05C 19/008 Accessories or implements for use in connection with applying particulate materials to surfaces; not provided elsewhere in B05C19/00
• CPC Class Codes: B22F 10/10 Formation of a green body
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/366 Scanning parameters, e.g. hatch distance or scanning strategy
• CPC Class Codes: B22F 10/85 for controlling or regulating additive manufacturing processes
• CPC Class Codes: B22F 12/41 characterised by the type, e.g. laser or electron beam
• CPC Class Codes: B22F 2003/1052 assisted by energy absorption enhanced by the coating or powder
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 3/004 Filling molds with powder feeding material to presses in general B30B15/302
• CPC Class Codes: B22F 3/105 by using electric current other than for infrared radiant energy, laser radiation or plasma B22F3/11 takes precedence; by ultrasonic bonding B22F3/115 takes precedence
• CPC Class Codes: B22F 3/26 Impregnating making ferrous alloys by impregnation C22C33/0242
• CPC Class Codes: B22F 7/02 of composite layers B22F7/002 takes precedence
• CPC Class Codes: B23K 2103/30 Organic material
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 2103/52 Ceramics
• CPC Class Codes: B23K 26/08 Devices involving relative movement between laser beam and workpiece
• CPC Class Codes: B23K 26/082 Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• CPC Class Codes: B23K 26/0821 using multifaceted mirrors, e.g. polygonal mirror
• CPC Class Codes: B23K 26/32 : taking account of the properties of the material involved
• CPC Class Codes: B23K 26/324 : involving non-metallic parts
• CPC Class Codes: B23K 26/34 : Laser welding for purposes other than joining
• CPC Class Codes: B29C 35/045 : using gas or flames
• CPC Class Codes: B29C 41/12 : Spreading-out the material on a substrate , e.g. on the surface of a liquid
• CPC Class Codes: B29C 41/46 : Heating or cooling
• CPC Class Codes: B29C 64/153 : using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• CPC Class Codes: B33Y 10/00 : Processes of additive manufacturing
• CPC Class Codes: B33Y 30/00 : Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: C04B 35/64 : Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: C23C 24/08 : by application of heat or pressure and heat C23C24/04 takes precedence
• CPC Class Codes: C23C 24/10 : with intermediate formation of a liquid phase in the layer
• CPC Class Codes: C23C 26/02 : applying molten material to the substrate
• CPC Class Codes: G05B 19/4099 : Surface or curve machining, making 3D objects, e.g. desktop manufacturing
• CPC Class Codes: G05B 19/41 : characterised by interpolation, e.g. the computation of intermediate points between programmed end points to define the path to be followed and the rate of travel along that path G05B19/25, G05B19/31, G05B19/37, G05B19/39, G05B19/40 take precedence
• CPC Class Codes: G05B 2219/49013 : Deposit layers, cured by scanning laser, stereo lithography SLA, prototyping
• CPC Class Codes: G05B 2219/49018 : Laser sintering of powder in layers, selective laser sintering SLS
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

An apparatus and method for producing parts by selective laser sintering are disclosed. The disclosed method selectively sinters a first layer of heat-fusible powder by directing a laser beam so that it scans the first layer in a first direction to sinter a first cross-section of the part. A second layer of the heat-fusible powder is then disposed over the first layer, and the next cross-section of the part is selectively sintered by the laser being scanned in a different direction from the first direction, for example in a direction perpendicular to the first direction. The cross-scanning resulting from scanning in different directions provides parts with structural strength which is not dependent upon orientation, with more uniform surfaces and textures, and with reduced distortion. In addition, each of the layers may have its outlined traced prior to the scanning, to further define the edges of the cross-section.

Claims

1. A method of producing parts, comprising:

disposing a first layer of heat-fusible powder at a target surface;

scanning a selected portion of said first layer with an energy beam in such a manner as to fuse the powder thereat, said scanning of said first layer being done in a first direction;

disposing a second layer of said powder over said first layer after said scanning step; and

scanning a selected portion of said second layer with said energy beam in such a manner as to fuse the powder thereat, said scanning of said second layer being done in a second direction.

2. The method of claim 1, wherein said step of scanning a selected portion of said second layer is also done in such a manner as to fuse the powder in said second layer to a fused portion of said first layer.

3. The method of claim 1, wherein said energy beam is a laser beam.

4. The method of claim 1, wherein said second direction is perpendicular to said first direction.

5. The method of claim 4, further comprising:

disposing a third layer of powder over said second layer of powder after said step of scanning a selected portion of said second layer; and

scanning a selected portion of said third layer with an energy beam in such a manner as to fuse the powder thereat, said scanning of said third layer being done in said first direction.

6. The method of claim 1, further comprising:

disposing a third layer of powder over said second layer of powder after said step of scanning a selected portion of said second layer; and

scanning a selected portion of said third layer with an energy beam in such a manner as to fuse the powder thereat, said scanning of said third layer being done in said first direction.

7. The method of claim 1, further comprising:

after said step of disposing said first layer of powder, tracing the outline of a first cross-section of a part with said energy beam in said first layer in such a manner as to fuse the powder thereat.

8. The method of claim 7, wherein said step of scanning a selected portion of said first layer is performed after said tracing step.

9. The method of claim 1, wherein said scanning steps sinter the selected portions of said first and second layers.

10. A part produced by a method comprising the steps of:

disposing a first layer of heat-fusible powder at a target surface;

scanning a selected portion of said first layer with an energy beam in such a manner as to fuse the powder thereat, said scanning of said first layer being done in a first direction;

disposing a second layer of said powder over said first layer after said scanning step; and

scanning a selected portion of said second layer with said energy beam in such a manner as to fuse the powder thereat, said scanning of said second layer being done in a second direction.

11. The part of claim 10, wherein said step of scanning a selected portion of said second layer is also done in such a manner as to fuse the powder in said second layer to a fused portion of said first layer.

12. The part of claim 10, wherein said energy beam is a laser beam.

13. The part of claim 10, wherein said second direction is perpendicular to said first direction.

14. The part of claim 13, wherein the method further comprises:

disposing a third layer of powder over said second layer of powder after said step of scanning a selected portion of said second layer; and

scanning a selected portion of said third layer with an energy beam in such a manner as to fuse the powder thereat, said scanning of said third layer being done in said first direction.

15. The part of claim 10, wherein the method further comprises:

disposing a third layer of powder over said second layer of powder after said step of scanning a selected portion of said second layer; and

scanning a selected portion of said third layer with an energy beam in such a manner as to fuse the powder thereat, said scanning of said third layer being done in said first direction.

16. The part of claim 10, wherein the method further comprises:

after said step of disposing said first layer of powder, tracing the outline of a first cross-section of a part with said energy beam in said first layer in such a manner as to fuse the powder thereat.

17. The part of claim 16, wherein said step of scanning a selected portion of said first layer is performed after said tracing step.

18. The part of claim 10 wherein said scanning steps sinter the selected portions of said first and second layers.

19. An apparatus for performing selective laser sintering, comprising:

a target surface;

means for disposing a layer of heat-fusible powder at said surface;

an energy source for producing an energy beam, said energy beam having sufficient power to fuse together portions of said heat-fusible powder exposed to said energy beam; and

means for controlling the energy beam from said energy source in such a manner as to scan, in a first direction, a first layer of said powder at said target surface, and to scan, in a second direction, a second layer of powder overlying said first layer of powder.

20. The apparatus of claim 19, wherein said energy source comprises a laser.

21. The apparatus of claim 20, wherein said controlling means comprises:

a mirror for directing said energy beam, said mirror being tiltable responsive to an electrical signal; and

a computer having an output connected to said mirror, for tilting the mirror according to a program stored therein, so that said energy beams scans said first layer in said first direction and said second layer in said second direction.

22. The apparatus of claim 21, wherein said controlling means further comprises:

means for directing the energy beam between said laser and said mirror.

23. The apparatus of claim 21, wherein said stored program further controls said mirror in such a manner that said energy beam traces an outline of a cross-section of said part in said first and second layers.