Simplified stereolithographic object formation methods of overcoming minimum recoating depth limitations

• US 6,179,601 B1
• Filed: 05/10/1999
• Issued: 01/30/2001
• Est. Priority Date: 08/29/1997
• Status: Expired due to Term

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Inventors: Kruger, Theodore R., Manners, Chris R., Nguyen, Hop D.
• Primary Examiner(s): Tentoni, Leo B.
• Application Number:
  US09/307,935
• Time in Patent Office: 631 Days
• Field of Search: 264/308, 264/401, 264/497, 700/120, 425/174.4, 425/375
• US Class Current: 425/174.4
• 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 41/36 Feeding the material on to the mould, core or other substrate
• CPC Class Codes: B29C 64/124 using layers of liquid which are selectively solidified
• 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

Abstract

A rapid prototyping and manufacturing (e.g. stereolithography) method and apparatus for making high resolution objects utilizing low resolution materials which are limited by their inability to reliably form coatings of a desired thickness. The formation of coatings of such materials is limited to a Minimum Recoating Depth (MRD), when formed over entirely solidified laminae, which is thicker than the desired layer thickness or object resolution. Data manipulation techniques result in layers of material (and laminae) of the object being categorized as non-consecutive primary layers (laminae) and secondary layers (laminae) positioned intermediate to the primary layers (laminae). Substantially, all portions of primary laminae are exposed in association with primary layers and portions of the secondary laminae are formed in association with their respective secondary layers while other portions of the secondary laminae are formed in association with primary layers so as to form the object with a higher resolution than that dictated by the spacing between the primary layers. Recoating techniques are described which can be used when the thickness between consecutive layers is less than a leading edge bulge phenomena that results from the use of a particular recoating device such that direction of sweeping and/or order of sweeping of the recoating device is varied between consecutive primary layers.

Claims

1. An apparatus for forming from a build material at least a portion of three-dimensional object from a plurality of adhered laminae, comprising in combination:

means for forming successive layers of material adjacent to any last formed layers of material in preparation for forming subsequent laminae of the object;

a data manipulation system for identifying at least a portion of non-consecutive layers as primary layers and for identifying layers intermediate to the primary layers as secondary layers;

an exposure system for exposing the build material to prescribed stimulation, in association with the primary layers, to form substantially all portions of laminae associated with the primary layers and to form portions of laminae associated with the secondary layers and for exposing at least a portion of the material to prescribed stimulation, in association with the secondary layers, to form at least some outward-facing portions of the laminae associated with the secondary layers;

such that at least a portion of the three-dimensional object is formed from a plurality of adhered laminae with an object resolution substantially equal to or better than the resolution defined by a thickness between successive layers.

2. The apparatus of claim 1 wherein the means for forming successive layers forms every other layer as a primary layer.

3. The apparatus of claim 1 wherein the means for forming successive layers forms the at least some outward-facing portions of the laminae associated with the secondary layers so as to include substantially all outward-facing portions of the laminae associated with the secondary layers.

4. The apparatus of claim 1 wherein the means for forming successive layers form the at least some outward-facing portions of the laminae associated with the secondary layers so as to include up-facing portions of the laminae associated with the secondary layers.

5. The apparatus of claim 1 wherein the exposure system exposes the build material using vector data and when exposing laminae of build material in association with the secondary layers of boundaries, downward facing regions and up-ward facing regions associated with the secondary layers are also exposed.

6. The apparatus of claim 5 wherein the exposure system exposes laminae of build material so that the boundaries exposed in association with the secondary layers include down-facing boundaries, up-facing boundaries, and continuing boundaries.

7. The apparatus of claim 1 wherein the means for forming successive layers and the exposure system creates a spacing between successive layers that is less than a minimum recoating depth (MRD) which is considered desirable for forming coatings over entirely solidified laminae.

8. The apparatus of claim 7 wherein the means for forming successive layers and the exposure system creates a spacing between successive primary layers that is at least as large as the MRD of the material.

9. The apparatus of claim 7 wherein the data manipulation system tailors data representing the object to account for a minimum solidification depth of the medium being greater than the thickness between successive layers.

10. The apparatus of claim 1 wherein the means for forming successive layers forms every 4th layer as a primary layer.

11. The apparatus of claim 1 wherein the means for forming successive layers and the exposure system creates layers such that spacing between the primary layers is variable.

12. The apparatus of claim 1 wherein the build material is a photopolymer.

13. The apparatus of claims 1 wherein the exposure system exposes build material simultaneously when forming successive layers.

14. The apparatus according to claim 1 wherein the exposure system further includes a laser.

15. The apparatus according to claim 11 wherein the means for forming successive layers of build material further includes a movable support platform and a recoating device.

16. The apparatus according to claim 15 wherein the recoating device employs a vacuum.

17. An apparatus for forming from a build material at least a portion of a three-dimensional object from a plurality of adhered laminae, comprising in combination:

means for forming successive layers of build material adjacent to any last formed layers of build material in preparation for forming subsequent laminae of the object, a portion of the successive layers being primary layers spaced one from the other and some being secondary layers positioned intermediate to the primary layers, wherein a spacing between successive primary layers is greater than or equal to an MRD of the material and the spacing between successive layers is less than the MRD of the material;

means for selectively exposing the primary layers to form at least majority portions of primary laminae including at least a portion of the external boundary regions of the laminae in association therewith and for selectively exposing the secondary layers to form at least minority portions of the secondary laminae in association therewith such that

the exposure of the primary layers and secondary layers results in adhesion of laminae to previously formed laminae so as to form at least a portion of the object from a plurality of adhered laminae with a resolution substantially equal to or better than the resolution defined by a thickness between successive layers.

18. An apparatus for forming from a build material at least a portion of a three-dimensional object from a plurality of adhered laminae, comprising in combination:

means for forming successive layers of build material adjacent to any last formed layers of material in preparation for forming subsequent laminae of the object;

data manipulation means for

(i) identifying a portion of non-consecutive layers as primary layers;

(ii) identifying layers intermediate to the primary layers as secondary layers;

(iii) identifying continuing regions of the object as regions which are neither up-facing nor down-facing; and

(iv) identifying outward-facing-regions of the object as regions which are either up-facing, down-facing or both;

means for exposing at least portions of build material to prescribed stimulation, in association with the primary layers, to form at least portions of laminae associated with the primary layers and to form portions of laminae associated with the secondary layers and for exposing at least portions of the build material to prescribed stimulation, in association with the secondary layers, to form at least a portion of the outward-facing regions of the laminae associated with the secondary layers;

a such that exposure of interior portions of continuing regions associated with the primary layers and the secondary layers occurs substantially in association with only the primary layers or in association with exposure of outward-facing portions associated with the secondary layers, to thereby form at least a portion of the three-dimensional object from a plurality of adhered laminae with an object resolution substantially equal to or better than the resolution defined by a thickness between successive layers.

22. The apparatus of claim 18 wherein the build material is a photopolymer.

19. Apparatus for forming from a build material at least a portion of a three-dimensional object from a plurality of adhered laminae, comprising in combination:

forming successive layers of build material adjacent to any last formed layers of build material in preparation for forming subsequent laminae of the object, a portion of the successive layers being primary layers spaced one from the other by an odd number of secondary layers positioned intermediately therebetween;

means for selectively exposing the primary layers to form at least majority portions of primary laminae in association therewith and to form at least portions of the secondary laminae and for selectively exposing the secondary layers to form at least minority portions of the secondary laminae in association therewith such that the exposure of the primary layers and secondary layers results in adhesion of laminae to previously formed laminae so as to form the at least portion of the object from a plurality of adhered laminae; and

a recoating device used during forming the primary layers and at least some of the secondary layers wherein the recoating device sweeps at or near a surface of the build material a desired number of times such that the sweeping directions and/or order of sweeping over successive primary laminae vary.

23. The apparatus of claim 19 wherein the build material is a powder material that is selectively solidified in layers.

24. The apparatus of claim 19 wherein the build material is a liquid photopolymer material that is selectively solidified in layers.

20. Apparatus for forming from a build material at least a portion of a three-dimensional object from a plurality of adhered laminae, comprising the steps of;

means for forming successive layers of build material adjacent to any last formed layers of build material in preparation for forming subsequent laminae of the object, a portion of the successive layers being primary layers spaced one from the other by an even number of secondary layers positioned intermediately therebetween;

means for selectively exposing the primary layers to form at least majority portions of primary laminae in association therewith and to form at least portions of secondary laminae and for selectively exposing the secondary layers to form at least minority portions of the secondary laminae in association therewith such that the exposure of the primary layers and the secondary layers results in adhesion of laminae to previously formed laminae so as to form at least a portion of the object from a plurality of adhered laminae; and

a recoating device used during forming the primary layers and at least some of the secondary layers sweeps at or near a surface of the material a desired number of times such that sweeping directions over successive primary laminae occur in different directions or a different order of directions, and a different number of sweeps of the recoating device are made over at least two laminae within a group of laminae comprising a primary lamina, a next consecutive primary lamina and all secondary laminae therebetween.

21. Apparatus for forming from a build material at least a portion of a three-dimensional object from a plurality of adhered laminae, comprising in combination:

a data manipulation system for identifying a portion of non-consecutive cross-sections as primary cross sections and identifying cross-sections intermediate to the primary cross-sections as secondary cross-sections;

means for forming, in association with the primary cross-sections, substantially all portions of laminae associated with the primary cross-sections and forming portions of laminae associated with secondary cross-sections; and

for forming, in association with the secondary cross-sections, at least some outward-facing portions of the laminae associated with the secondary cross-sections including at least some of any flat up-facing or flat down-facing regions such that at least a portion of the three dimensional object is formed from a plurality of adhered laminae with an object resolution substantially equal to or better than the resolution defined by a thickness between successive layers.