Region-Based Supports for Parts Produced by Solid Freeform Fabrication

• US 20090072447A1
• Filed: 09/17/2008
• Published: 03/19/2009
• Est. Priority Date: 09/17/2007
• Status: Active Grant

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Inventors: Wang, Hongqing V., Hull, Charles W., West, John Corbin, Mojdeh, Medhi, Kulkarni, Rajeev
• Granted Patent: US 8,046,097 B2
• Time in Patent Office: Days
• US Class Current: 264/401
• 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 50/02 for controlling or regulating additive manufacturing processes

Abstract

Methods for generating supports (30) for parts (50) produced by solid freeform fabrication (“SFF”) are disclosed. The method includes defining a plurality of layers (L) that make up the part, and for each layer, determining those regions (R) that require support. The method also includes merging the regions for the different layers (L) into one or more common regions that require support, and providing at least one support for each of the one or more common regions. The result is that fewer supports are used as compared to conventional SFF fabrication methods.

Claims

1. A method of supporting on a build pad a part formed by solid freeform fabrication (SFF), comprising:

defining a plurality of layers that make up the part;

for at least one layer, determining regions that require support by determining one or more portions of the layer that are self-supporting;

merging regions of different layers into one or more common regions for the part; and

providing at least one support for the one or more common regions.

2. A method in accordance with claim 1, wherein the regions are defined by one or more pixels, and further comprising:

for at least one layer, analyzing a steepness associated with the one or more pixels and identifying those pixels having associated therewith a sufficient steepness to be deemed self-supporting.

3. A method in accordance with claim 2, wherein analyzing steepness includes establishing steepness in orthogonal directions within the layer, and deeming those pixels having a threshold steepness in both orthogonal directions within the layer to be self-supporting.

4. A method in accordance with claim 1, wherein the one or more common regions have an associated size, and wherein providing the at least one support for the common regions includes:

providing the at least one support with a cross-sectional area in a range between about 0.1% and about 10% of the size of the corresponding common region.

5. A method in accordance with claim 1, further comprising:

removing the part from the build pad;

removing from the part the at least one support for the one or more common regions; and

removing a part abnormality formed by the at least one support.

6. A method in accordance with claim 1, wherein providing the at least one support comprises:

identifying one or more local maxima of the part;

identifying at least one island associated with the local maxima;

identifying a largest cross-section for the island and a corresponding number of pixels for the largest cross-section for the island; and

defining a total number of support pixels required to adequately support the island.

7. A method in accordance with claim 6, wherein the total number of support pixels required to adequately support the island is at least 1% of the number of pixels of the largest cross-section of the corresponding island.

8. A method in accordance with claim 1, further comprising:

providing at least one support for at least one local maximum.

9. A method in accordance with claim 8, further comprising:

calculating a centroid for the one or more common regions; and

providing at least one support at the centroid.

10. A method in accordance with claim 9, further comprising:

providing a number NS of surface supports, wherein;

NS=NT−

(NM+NC),

where NT is a total number of support pixels required, NM is a number of local maxima support pixels required, and NC is a number of centroid pixels required.

11. A method in accordance with claim 1, wherein the at least one support has a cross-sectional size of between 4×

4 pixels and 16×

16 pixels.

12. A method in accordance with claim 1, wherein the at least one support has a base at a build pad and an anchor at the part, wherein the base has a larger cross-sectional size than that of the anchor.

13. A method of determining one or more geometries for one or more supports for a part produced by solid freeform fabrication, the method comprising:

determining a general surface of the part to which the one or more supports join to the part;

dividing the surface into a plurality of regions that require at least one support; and

calculating a cross-sectional area of the at least one support for the region that contacts the part based upon a ratio of a size of the region to a size of the cross-sectional area.

14. A method according to claim 13, wherein the size of the cross-sectional area for the at least one support is between about 0.1% and about 10% of the size of the corresponding region.

15. A method in accordance with claim 14, wherein the size of the cross-sectional area for the at least one support is about 2% of the size of the corresponding region.

16. A method in accordance with claim 13, wherein the cross-sectional area of a portion of the support distant from the part is different than the cross-sectional area of the support that contacts the part.

17. A method in accordance with claim 13, wherein the cross-sectional area of the support that contacts the part is based upon the size of the region being supported.

18. A method in accordance with claim 13, further comprising:

forming the at least one support for the region.

19. A method of generating support structures for a three-dimensional part formed by solid freeform fabrication relative to a build pad, comprising the steps of:

slicing a part model to generate part voxels;

creating two-dimensional layer data and pixel data from the part voxels;

determining support anchor locations from the layer data and pixel data;

creating support voxels; and

generating the support structures on the build pad based on the support voxels.

20. A method in accordance with claim 19, wherein generating the support structures includes for one or more of the support structures, forming a support base attached to the build pad, and a support tip attached to the part, including forming the support base to be larger than the support tip.

21. A method in accordance with claim 20, further comprising forming the support tip to be smaller than a single pixel.

22. A method in accordance with claim 20, further comprising forming the support tip to have no more than a single pixel within ten layers or fewer from the part.

23. A method in accordance with claim 20, wherein the support tip is anchored to the part at an anchor that is one to four layers deep into the part.