Stereolithographic supports

• US 20030178750A1
• Filed: 04/09/2003
• Published: 09/25/2003
• Est. Priority Date: 01/28/2000
• Status: Active Grant

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Inventors: Manners, Chris R., Kulkarni, Rajeev B.
• Granted Patent: US 6,797,351 B2
• Time in Patent Office: Days
• US Class Current: 264/401
• CPC Class Codes: B29C 64/129 characterised by the energy source therefor, e.g. by global irradiation combined with a mask
• CPC Class Codes: B29C 64/40 Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: Y10T 428/15 Sheet, web, or layer weakened to permit separation through thickness

Abstract

An improved stereolithographic process for forming three-dimensional objects using an improved support structure is disclosed. The support structure is formed by using differential curing of the liquid media material to form solid supports with weak points at selected locations to facilitate support removal from a three-dimensional object and minimize post-processing.

Claims

1. A method of forming a three-dimensional object using stereolithography to stimulate a liquid medium to selectively change state to a solid to form the three-dimensional object comprising:

(a) retaining in a container a liquid state medium capable of transformation to a solid state upon the selective application of energy to stimulate a change of state;

(b) receiving a data description of an object to be formed;

(c) manipulating the received data to optimize the data for use in selectively applying energy to stimulate the change of state of the liquid medium to form an object; and

(d) selectively applying the energy to the liquid medium in the container to form the three-dimensional object layer by layer, the object having support structure with an intermediate region connecting interfacing regions, the support structure contacting the object at at least a down-facing interfacing region, the support structure selectively having different energy levels applied to it at at least the down-facing interfacing region than do the intermediate region and the object to thereby create weak points with less solidification in the solid state transformed liquid medium than the intermediate region and the three-dimensional object at at least the down-facing interfacing regions to facilitate ease of removal of the support structure from a completed three-dimensional object.

2. The method according to claim 1 further comprising providing the support structure with an up-facing interfacing region, the up-facing interfacing region contacting the three-dimensional object and having weak points with less solidification in the solid state transformed liquid medium than the intermediate region and the three-dimensional object to facilitate ease of removal of the support structure from the completed three-dimensional object.

3. The method according to claim 1 further comprising providing the support structure with vertically extending strands, the strands further having at least a down-facing interfacing region that contacts the three-dimensional object.

4. The method according to claim 3 further comprising providing two orthogonally intersecting sides to each strand, one side being an object interfacing side and a second side being a non-interfacing side.

5. The method according to claim 4 further comprising graphically patterning the two orthogonally intersecting sides into triangles.

6. The method according to claim 3 further comprising connecting adjacent strands with projections to reinforce the support structure.

7. The method according to claim 6 further comprising reinforcing the support structure with triangular braces.

8. The method according to claim 1 further comprising using a laser to selectively apply energy to the liquid medium.

9. The method according to claim 8 further comprising using a photopolymer resin as the liquid medium.

10. The method according to claim 1 further comprising using an elevatable platform in the container to raise and lower the three-dimensional object in the liquid medium.

11. The method according to claim 9 further comprising selectively applying the laser to selectively cure the photopolymer to form the three-dimensional part with support structure, the part and the support structure being differentially cured so that the part and the support structure have different thicknesses, the thicknesses being the least at the interfacing regions.

12. A stereolithographic part formed by selective stimulation of a liquid medium to a solid state comprising:

(a) at least one support structure with an intermediate region connecting opposing interfacing regions, the interfacing regions contacting the part at interfacing boundaries;

(b) the solid state intermediate region having a first solid cure depth; and

(c) the interfacing regions having a second solid cure depth, the second solid cure depth being sufficiently less than the first solid cure depth to create weak points where the support structure is easily separable from the part.

13. The part according to claim 12 wherein the interfacing regions further comprise up-facing interfacing regions and down-facing interfacing regions.

14. The part according to claim 13 wherein the part has a third solid cure depth greater than the second solid cure depth.

15. The part according to claim 14 wherein the support structure further comprises vertically oriented strands.

16. The part according to claim 15 wherein the strands each have the opposing interfacing regions connected to an object interfacing side.

17. The part according to claim 16 wherein the strands each have an object non-interfacing side orthogonally intersecting the object intersecting side.

18. The part according to claim 16 wherein the object non-interfacing side and the object intersecting side are graphically patterned triangles.

19. The part according to claim 17 wherein adjacent vertically oriented strands are connected and reinforced with at least one projection extending therebetween.

20. The part according to claim 13 wherein the support structure is reinforced with triangular braces.

21. The part according to claim 12 wherein the support structure to reinforce the part includes gussets.

22. The part according to claim 21 wherein the gussets are formed from horizontal strips and angular strips connected to the part, the strips being separated by spaces to facilitate drainage of the liquid medium during part generation.