Method of and apparatus for making a three-dimensional object by stereolithography

• US 5,711,911 A
• Filed: 06/07/1995
• Issued: 01/27/1998
• Est. Priority Date: 04/18/1988
• Status: Expired due to Term

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Inventors: Hull, Charles W.
• Primary Examiner(s): Tentoni, Leo B.
• Application Number:
  US08/473,834
• Time in Patent Office: 965 Days
• Field of Search: 264/308, 264/401, 425/174.4, 156/272.8, 156/273.3, 156/273.5, 156/275.5, 156/307.1, 156/379.6, 427/510, 427/512, 427/553, 427/554, 427/555, 118/620, 250/492.1, 364/468, 364/476, 364/468.27, 365/106, 365/107, 395/119
• US Class Current: 264/401
• CPC Class Codes: B29C 64/135 the energy source being concentrated, e.g. scanning lasers or focused light sources
• CPC Class Codes: B29C 64/40 Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof
• CPC Class Codes: B29C 67/02 Moulding by agglomerating B29C67/20 takes precedence
• 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: B33Y 50/02 for controlling or regulating additive manufacturing processes
• CPC Class Codes: B44B 1/006 using computer control means
• CPC Class Codes: G01J 1/4257 applied to monitoring the characteristics of a beam, e.g. laser beam, headlamp beam monitoring arrangements for lasers in general H01S3/0014
• CPC Class Codes: G03F 7/0037 Production of three-dimensional images
• CPC Class Codes: G03F 7/70416 2.5D lithography
• CPC Class Codes: G05B 2219/49013 Deposit layers, cured by scanning laser, stereo lithography SLA, prototyping
• CPC Class Codes: G06T 17/00 Three dimensional [3D] modelling, e.g. data description of 3D objects
• CPC Class Codes: G06T 17/10 Constructive solid geometry [CSG] using solid primitives, e.g. cylinders, cubes
• CPC Class Codes: G06T 17/20 Finite element generation, e.g. wire-frame surface description, tesselation

Abstract

An improved method for stereolithographically making an object by alternating the order in which similar sets of vectors are exposed over two or more layers. In another method, a pattern of tightly packed hexagonal tiles are drawn. Each tile is isolated from its neighboring tiles by specifying breaks of unexposed material between the tiles. Using an interrupted scan method, vectors are drawn with periodic breaks along their lengths. In another method, modulator and scanning techniques are used to reduce exposure problems associated with the acceleration and deceleration of the scanning system when jumping between vectors or changing scanning directions.

Claims

1. A method for forming at least a portion of a three-dimensional object on a layer-by-layer basis from a medium solidifiable upon selective exposure to synergistic stimulation according to data representations corresponding to said three-dimensional object, comprising the steps of:

a) applying a layer of flowable material capable of solidification upon exposure to synergistic stimulation onto any previously solidified layer of the three-dimensional object;

b) selectively exposing said layer to synergistic stimulation to form a layer of said three-dimensional object;

c) repeating steps a) and b) for subsequent layers until at least the portion of said three-dimensional object is formed and wherein the steps of exposing said layers further comprise exposing at least a portion of at least one layer with interrupted, non-overlapping points of exposure to synergistic stimulation such that said at least portion is solidified as substantially discrete and non-overlapping regions.

2. The method of claim 1 wherein the step of selectively exposing said at least one layer further comprises selectively applying sufficient synergistic stimulation to solidify said discrete, non-overlapping points of exposure to a depth of at least one layer thickness.

3. The method of claim 1 wherein the step of selectively exposing said at least one layer further comprises selectively exposing at least a portion of a boundary of said at least one layer with a continuous exposure before selectively exposing an interior portion of said at least one layer with non-overlapping points of exposure.

4. The method of claim 1 wherein the step of selectively exposing said at least one layer further comprises selectively exposing at least a portion of a boundary of said layer with a continuous exposure after selectively exposing an interior portion of said at least one layer with non-overlapping points of exposure.

5. The method of claim 2 further comprising the step of staggering the locations of said discrete, non-overlapping points of exposure on every other layer such that said discrete points of exposure on one layer are centered above non-exposed regions on an adjacent layer.

6. An improved method for forming at least a portion of a three dimensional object on a layer by layer basis from a medium solidifiable upon exposure to synergistic stimulation, of the type wherein successive layers of the medium are applied and selectively solidified to form layers of the three-dimensional object, and wherein the solidified layers of the three-dimensional object are adhered together to form said three-dimensional object, each layer of the medium having a desired thickness and being selectively solidified through the scanning of synergistic stimulation corresponding to a cross-section of the object, the improvement comprising:

scanning at least a portion of at least one layer with synergistic stimulation as discrete points of exposure such that at least one layer of the three-dimensional object is formed at least partially by non-overlapping discrete regions of solidified material.

7. The method of claim 6 further comprising the step of curing the discrete points of exposure to a depth greater than the desire thickness to ensure adhesion between at least two adjacent layers.

8. The method of claim 7 further comprising the step of curing the discrete points of exposure such that adhesion occurs between cross-sections of at least two previous layers.

9. The method of claim 6 further comprising the step of scanning said at least one layer with a continuous path of exposure on at least a portion of the at least one layer to form an outside facing surface of the three-dimensional object.

10. The method of claim 9 wherein the step of scanning said continuous path of exposure on the at least one layer occurs prior to scanning discrete points of exposures on the at least one layer.

11. The method of claim 6 wherein the step of scanning the layer further comprises uniformly spacing the discrete points of exposure on the at least one layer.

12. The method of claim 11 wherein the at least one layer is a plurality of layers and further comprising the step of staggering the locations of the discrete points of exposure on a layer such that the locations are shifted from the locations of discrete points of exposure on a previous layer.

13. The method of claim 12 wherein the step of staggering further comprises locating the points of exposure on a layer such that the points of exposure are centered between points of exposure on a previous layer and a subsequent layer.

14. The method of claim 6 wherein the discrete non-overlapping points of exposure are bullet shaped when solidified.

15. The method of claim 6 wherein the step of scanning further comprises spacing the discrete non-overlapping points of exposure in hexagonal formations such that each point of exposure has six immediately adjacent points of exposure.

16. An improved apparatus for forming at least a portion of a three-dimensional object on a layer-by-layer basis from a medium solidifiable upon exposure to synergistic stimulation, comprising means for forming successive layers of the medium and means for selectively solidifying cross-sectional layers of the three-dimensional object, wherein the solidified cross-sectional layers of the three-dimensional object are adhered together to form said at least portion of the three-dimensional object, each layer of the medium having a desired thickness and being selectively solidified through the scanning of synergistic stimulation corresponding to a cross-section of the object, the improvement comprising:

a means for exposing at least a portion of at least one layer with synergistic stimulation as discrete, non-overlapping points of exposure such that said cross-sectional layer is at least partially formed with some solidified regions separated by unsolidified regions of the medium.

17. The apparatus of claim 16 herein the means for scanning further comprises means for spacing the scanned points of exposure on said layer by a distance not substantially greater than a solidified diameter of the points of exposure.

18. The apparatus of claim 17 further comprising means for curing the points of exposure to a depth greater than a layer thickness to ensure adhesion between at least two adjacent cross-sectional layers.

19. The apparatus of claim 16 further comprising means for scanning said layers with a continuous path of exposure on at least a portion of an outside facing surface of said at least one layer.

20. The apparatus of claim 19 further comprising means for scanning said continuous path of exposure prior to scanning an interior portion of said at least one layer with discrete points of exposure.

21. The apparatus of claim 16 wherein the at least one layer is a plurality of layers and further comprising means for locating the points of exposure on each layer such that the locations are shifted from locations of the points of exposure on a previous layer.

22. The apparatus of claim 20 further comprising means for staggering the exposures on subsequent layers such that the points of exposure on a given layer are centered over an unsolidified region of a previous layer and below an unsolidified region of a next layer.

23. An improved method for forming at least a portion of a three dimensional object on a layer by layer basis from a medium solidifiable upon exposure to synergistic stimulation, of the type wherein successive layers of the medium are applied and selectively solidified to form layers of the three-dimensional object, and wherein the solidified layers of the three-dimensional object are adhered together to form said three-dimensional object, each layer of the medium having a desired thickness and being selectively solidified through the scanning of synergistic stimulation corresponding to a cross-section of the object the improvement comprising:

scanning at least at least one portion of a layer with synergistic stimulation using vector data wherein the exposure of the medium is interrupted at a plurality of intermediate points along at least one vector.