Method and apparatus for production of high resolution three-dimensional objects by stereolithography

• US 5,184,307 A
• Filed: 03/31/1989
• Issued: 02/02/1993
• 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: Smalley, Dennis R., Hull, Charles W., Lewis, Charles W., Tarnoff, Harry L., Spence, Stuart T., Nguyen, Hop D., Harlow, Richard A., Remba, David Z., Vorgitch, Tom J., Albert, David J., Stinebaugh, Phil
• Primary Examiner(s): RUGGIERO, JOSEPH F
• Application Number:
  US07/331,644
• Time in Patent Office: 1,404 Days
• Field of Search: 364/468, 364/474.05, 364/474.24, 364/476, 364/518, 364/521, 364/522, 264/22, 264/308, 264/40.1, 264/24, 264/241, 264/255, 425/174, 425/174.4, 427/43.1, 427/54.1, 156/58, 156/59, 156/273.3, 156/273.5, 156/275.5, 156/272.2, 156/378, 156/379.6, 156/379.8, 156/379.9
• US Class Current: 700/182
• CPC Class Codes: B29C 64/124 using layers of liquid which are selectively solidified
• CPC Class Codes: B29C 64/135 the energy source being concentrated, e.g. scanning lasers or focused light sources
• CPC Class Codes: B29C 64/386 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: B29C 64/40 Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof
• CPC Class Codes: B29K 2995/0073 smooth
• 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 50/00 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes
• 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 stereolithography system for generating a three-dimensional object by creating a cross-sectional pattern of the object to be formed at a selected surface of a fluid medium capable of altering its physical state in response to appropriate synergistic stimulation by impinging radiation, particle bombardment or chemical reaction, information defining the object being specially processed to reduce curl and distortion, and increase resolution, strength, accuracy, speed and economy of reproduction even for rather difficult object shapes, the successive adjacent laminae, representing corresponding successive adjacent cross-sections of the object, being automatically formed and integrated together to provide a step-wise laminar buildup of the desired object, whereby a three-dimensional object is formed and drawn from a substantially planar surface of the fluid medium during the forming process.

Claims

1. A system for producing a three-dimensional object comprising:

means for deriving data descriptive of cross-sections of the object from data descriptive of the object, including at least some skin data descriptive of at least part of at least one cross-section;

a container containing at least in part material capable of selective physical transformation upon exposure to the synergistic stimulation;

means for successively providing layers of said material;

means for selectively exposing said layers of said material to said synergistic stimulation in accordance with said data descriptive of said cross-sections of said object to form successive object cross-sections; and

control means for obtaining said cross-sectional descriptive data from said deriving means, and utilizing said data to control said means for successively providing said layers, and said means for selectively exposing said layers, to produce said three-dimensional object comprising said successively formed cross-sections.

2. The system of claim 1, wherein said deriving means derives at least some flat skin data descriptive of at least part of at least one cross-section.

3. The system of claim 1, wherein said deriving means derives at least some near-flat skin data descriptive of at least part of at least one cross-section.

4. The system of claim 1, wherein said deriving means derives at least some up-facing skin data descriptive of at least part of at least one cross-section.

5. The system of claim 1, wherein said deriving means derives at least some down-facing skin data descriptive of at least part of at least one cross-section.

6. A system for producing a three-dimensional object comprising:

means for producing synergistic stimulation;

means for deriving data descriptive of cross-sections of the object from data descriptive of the object, wherein said synergistic stimulation induces a corresponding cure width, and said deriving means derives at least some data descriptive of at least part of at least one cross-section and then offsets at least some of said data to at least partly compensate for said cure width;

a container containing at least in part material capable of selective physical transformation upon exposure to the synergistic stimulation;

means for successively providing layers of said material;

means for selectively exposing said layers of said material to said synergistic stimulation in accordance with said data descriptive of said cross-sections of said object to form successive object cross-sections; and

control means for obtaining said cross-sectional descriptive data from said deriving means, and utilizing said data to control said means for successively providing said layers, and said means for selectively exposing said layers, to produce said three-dimensional object comprising said successively formed cross-sections.

7. A method for producing a three-dimensional object comprising the steps of:

deriving data descriptive of cross-sections of the object from data descriptive of the object including deriving at least some skin data descriptive of at least part of at least one cross-section;

producing synergistic stimulation;

containing a material capable of selective physical transformation upon exposure to the synergistic stimulation;

successively producing layers of said material;

selectively exposing said layers of said material to said synergistic stimulation in accordance with said data descriptive of said cross-sections of said object to successively form object cross-sections; and

utilizing the cross-sectional descriptive data to control said successive producing, and selective exposing steps set forth above to produce said three-dimensional object comprising said successively formed object cross-sections.

8. The method of claim 7, further comprising deriving at least some flat skin data descriptive of at least part of at least one cross-section.

9. The method of claim 7, further comprising deriving at least some near-flat skin data descriptive of at least one cross-section.

10. The method of claim 7, further comprising deriving at least some up-facing skin data descriptive of at least one cross-section.

11. The method of claim 7, further comprising deriving at least some down-facing skin data descriptive of at least one cross-section.

12. A method for producing a three-dimensional object comprising the steps of:

producing synergistic stimulation, wherein said synergistic stimulation induces a corresponding cure width;

deriving data descriptive of cross-sections of the object from data descriptive of the object, including deriving at least some data descriptive of at least part of at least one cross-section, and offsetting at least some of said data to at least partly compensate for said cure width;

containing a material capable of selective physical transformation upon exposure to the synergistic stimulation;

successively producing layers of said material;

selectively exposing said layers of said material to said synergistic stimulation in accordance with said data descriptive of said cross-sections of said object to successively form object cross-sections; and

utilizing the cross-sectional descriptive object to control said successive producing, and selective exposing steps set forth above to produce said three-dimensional object comprising said successively formed object cross-sections.

13. A system for producing a three-dimensional object comprising:

means for deriving data descriptive of cross-sections of the object from data descriptive of the object, said data comprising a plurality of datum, and each datum comprising at least a beginning endpoint and an ending endpoint and representing a path to be taken by a beam of synergistic stimulation between the beginning and ending endpoints;

means for producing said beam of said synergistic stimulation;

a container containing, at least in part, material capable of selective physical transformation upon exposure to the beam of synergistic stimulation;

means for successively producing layers of said material;

means for successively exposing said layers of said material to said beam of synergistic stimulation in accordance with said data descriptive of said cross-sections of said object to successively form object cross-sections, the beginning and ending endpoints of each datum of said data being derived before the beam of synergistic stimulation begins tracing the path represented by the datum; and

control means for controlling said means for successively producing said layers, and said means for selectively exposing said layers, to produce said three-dimensional object comprising said successively formed object cross-sections.

14. The system of claim 13, wherein said data descriptive of the object comprises at least some polygons having vertices substantially spanning a surface of the object, and said deriving means rounds at least some of said vertices to slicing planes spaced along a slicing axis.

15. The system of claim 13, wherein said data descriptive of said object comprises at least some polygons having vertices substantially spanning a surface of the object, and said deriving means rounds at least some of said vertices to planes offset from slicing planes spaced along a slicing axis.

16. The system of claim 13, wherein said driving means derives at least some of said data which describes at least one cross-section having a variable thickness.

17. The system of claim 13, wherein at least one cross-section has a border surrounding an interior and said deriving means first derives data descriptive of said border of said at least one cross-section, and then derives data descriptive of said interior of said at least one cross-section utilizing a fill parameter.

18. The system of claim 13, wherein said deriving means derives at least some skin data descriptive of at least part of at least one cross-section.

19. The system of claim 13, wherein said deriving means derives at least some flat skin data descriptive of at least part of at least one cross-section.

20. The system of claim 13, wherein said deriving means derives at least some near-flat skin data descriptive of at least part of at least one cross-section.

21. The system of claim 13, wherein said deriving means derives at least some up-facing skin data descriptive of at least part of at least one cross-section.

22. The system of claim 13, wherein said deriving means derives at least some down-facing skin data descriptive of at least part of at least one cross-section.

23. The system of claim 13, wherein said deriving means scales at least some of said data descriptive of said cross-sections.

24. The system of claim 13, wherein said deriving means derives at least some cross-hatch data descriptive of at least part of at least one cross-section.

25. The system of claim 13, wherein said beam of synergistic stimulation induces a corresponding cure width, and said deriving means derives at least some vector data descriptive of at least part of at least one cross-section, and offsets at least some of said vector data to at least partly compensate for said cure width.

26. The system of claim 13, wherein said deriving means derives at least some vector data descriptive of at least one cross-section, and orders said vector data into blocks of vector data descriptive of said at least one cross-section.

27. The system of claim 13, wherein said deriving means derives at least some boundary data descriptive of at least part of at least one cross-section.

28. The system of claim 13 wherein at least one cross-section has a boundary encircling an internal portion, and the deriving means derives the data descriptive of the cross-sections by first generating data descriptive of the boundary of the at least one cross-section from the object descriptive data, and then mathematically generating data descriptive of the internal portion of the at least one cross-section from the data descriptive of the boundary of the at least one cross-section.

29. The system of claim 13 wherein at least one cross-section has a boundary encircling an internal portion, and the deriving means derives vector data descriptive of the at least one cross-section, by first generating boundary vector data descriptive of the boundary of the at least one cross-section from the object descriptive data, and then generating internal vector data descriptive of the internal portion of the at least one cross-section in a manner which is substantially resistant to misplacement of internal vector data.

30. The system of claim 13, wherein said data descriptive of the object comprises polygons substantially spanning a surface of the object, the polygons having vertices, and said deriving means rounds at least some of said polygon vertices to slicing planes spaced along a slicing axis.

31. The system of claim 13, wherein said data descriptive of the object comprises polygons substantially spanning a surface of the object, the polygons having vertices, and said deriving means rounds at least some of said polygon vertices to planes offset from slicing planes spaced along a slicing axis.

32. A system for producing a high-resolution reproduction of an object made up of stacked cross-sections of cured polymer, the system comprising:

converting means for converting CAD/CAM data descriptive of the object into data descriptive of cross-sections of the object;

laser means for producing a laser beam;

directing means for controllably directing the laser beam to draw a cross-section of the object using said cross-sectional data on the surface of a layer of liquid photopolymer, which layer of liquid photopolymer is situated with respect to already-cured stacked cross-sections of cured polymer such that the layer of liquid photopolymer cures to form a cross-section which adheres to the already-cured stacked cross-sections;

situating means for controllably situating the already cured stacked cross-sections with respect to the layer of liquid photopolymer; and

control means coupled to the converting means, the directing means, and the situating means for a) obtaining the cross-sectional data;

b) using said data to control the directing means and the situating means to form the stacked cross-sectional reproduction of the object out of cured photopolymer.

33. The system of claim 32 wherein the reproduction is within a tolerance of plus or minus 50 mils of the object.

34. The system of claim 33 wherein the reproduction is within a tolerance of plus or minus 5 mils of the object.

35. The system of claim 32 wherein the converting means converts the CAD/CAM data into vector data for at least one cross-section of the object, which vector data is used to control the movement of the laser beam on the surface of the liquid photopolymer.

36. The system of claim 35 wherein the vector data for at least one cross-section comprises a selected one of border vector data descriptive of the border of the cross-section, skin vector data descriptive of any outward surface portion of the cross-section, and hatch vector data descriptive of any interior solid portion of the cross-section.

37. The system of claim 36 wherein the skin vector data comprises flat skin vector data descriptive of flat outward surfaces on the cross-section, and near flat skin vector data descriptive of slanted outward surfaces on the cross-section.

38. The system of claim 35 wherein the vector data for said at least one cross-section is representative of a plurality of vectors, wherein each vector is comprised of a head and a tail endpoint, and a direction which points from the tail to the head endpoint, and the vector data further includes vector orientation information.

39. The system of claim 38 wherein the vector data is hatch vector data which comprises data representative of a selected one of vectors pointing in the X-direction, vectors pointing in the Y-direction, vectors pointing in both the X- and a Y-directions, and vectors pointing in directions which are 60 degrees and 120 degrees from the X-direction.

40. The system of claim 35 wherein the vector data is skin vector data which comprises data representative of a selected one of vectors pointing in the X-direction, and vectors pointing in the Y-direction.

41. The system of claim 35 wherein the vector data is border vector data which is representative of a plurality of border vectors situated to form a loop.

42. The system of claim 35 wherein the vector data comprises border vector data and a selected one of hatch and skin vector data, wherein the selected one of said hatch and skin vector data is generated from the border vector data.

43. The system of claim 42 wherein the border vector data includes border vector orientation information, and wherein the selected one of said hatch and skin vector data is generated by overlapping the border vector data with a plurality of spaced paths, and starting and stopping the generation of the selected one of said hatch and skin vector data at the intersection of a path with the border vector data, utilizing the border vector orientation information.

44. The system of claim 32 wherein the CAD/CAM data comprises a plurality of polygons which substantially surface the object.

45. The system of claim 44 wherein the CAD/CAM data is overlayed with a plurality of spaced slicing planes, wherein each slicing plane comprises a gird of spaced points, and wherein at least one polygon vertex is rounded to at least one of said points on any of said planes such that rounding error is minimized.

46. The system of claim 45 wherein the spacing between the slicing planes is variable.

47. The system of claim 44 wherein the CAD/CAM data also includes polygon orientation information.

48. The system of claim 45 wherein the rounding of the vertices of at least one polygon causes the flipping of at least one polygon and the system detects and corrects for the flipping of the at least one polygon utilizing the polygon orientation information.

49. The system of claim 44 wherein the CAD/CAM data is overlayed with a plurality of slicing planes spaced along a slicing axis, and the system derives border vector data for at least one cross-section from the intersection of at least one slicing plane with at least one polygon.

50. The system of claim 44 wherein the CAD/CAM data is overlayed with a plurality of planes offset from slicing planes spaced along a slicing axis, and the system drives border vector data for at least one cross-section from the intersection of at least one plane, which is offset from at least one slicing plane, with at least one polygon.

51. The system of claim 35 wherein the vector data is used to produce an oversized reproduction of an object, which reproduction is sanded down in a post-processing step.

52. The system of claim 35 wherein the vector data is used to produce an undersized reproduction of an object, which reproduction is coated with liquid photopolymer and cured in a post-processing step.

53. The system of claim 35 wherein the vector data is an average of the vector data of claims 51 and 52, which vector data is used to produce a reproduction of an object which is not sanded or filled in a post-processing step.

54. The system of claim 38 wherein the vector data is border vector data which is selectively offset for beam width compensation.

55. The system of claim 54 wherein the border vector data represents a loop of border vectors, and wherein the endpoints of the border vectors in the loop are successively offset to compensate for cure width by approximately one-half the cure width in a direction determined by utilizing the vector orientation information.

56. The system of claim 55 wherein the cure width is determined automatically by the system, and used for beam width compensation without manual intervention.

57. The system of claim 55 wherein the endpoints of the border vectors in a loop are successively offset by about one-half of the cure width, wherein the border vectors are then recomputed and pairwise checked for crossover with the other border vectors in the loop, and wherein the offsetting of the endpoints is backed up to eliminate crossover if it is detected.

58. A process for high resolution reproduction of an object, made up of stacked cross-sections of cured photopolymer, comprising the steps of:

converting CAD/CAM data descriptive of the object, and comprising a plurality of triangles which substantially surface the object, wherein substantially all of said plurality of triangles have vertices which join other triangles only at their vertices, into vector data descriptive of cross-sections of the object;

directing a laser beam to successively draw cross-sections on the surface of layers of liquid photopolymer using said descriptive cross-sectional data, which layers are situated with respect to already-cured stacked cross-sections which adhere to the already cured cross-sections; and

successively situating the already-cured stacked cross-sections with respect to said layers of liquid photopolymer;

wherein said reproduction is formed from said successively formed object cross-sections.

59. A process for high resolution reproduction of an object, made up of stacked cross-sections of cured photopolymer, comprising the steps of:

converting CAD/CAM data descriptive of the object, and comprising a plurality of polygons which substantially surface the object, into data descriptive of cross-sections of the object, which data includes at least some vector data, said converting step including generating a selected one of border vector data descriptive of the border of at least one cross-section, hatch vector data descriptive of an interior solid of at least one cross-section, and skin vector data descriptive of an exterior surface of at least one cross-section;

directing a laser beam to successively draw cross-sections on the surface of layers of liquid photopolymer using said descriptive cross-sectional data, which layers are situated with respect to already-cured stacked, cross-sections so that the layers cure to successively form cross-sections; and

successively situating the already-cured stacked cross-sections with respect to said layers of liquid photopolymer;

wherein said reproduction is formed from said successively formed object cross-sections.

60. The process of claim 59 wherein the converting step comprises the substeps of:

overlaying the CAD/CAM data with a plurality of spaced slicing planes, wherein at least one slicing plane comprises a grid of spaced points, wherein at least one polygon has vertices, and wherein at least one polygonal vertex is rounded to at least one of said points on any of said planes such that rounding error is minimized; and

generating vector data descriptive of at least one cross-section utilizing the intersection of at least one slicing plane with at least one polygon.

61. The process of claim 60 wherein the spacing of the slicing planes is variable.

62. The process of claim 60 wherein the rounding of the at least one polygonal vertex causes the flipping of at least one polygon, and the generating substep includes correcting for the flipping of the at least one polygon.

63. The process of claim 59 wherein the vector data is border vector data derived from the intersection of at least one slicing plane with at least one polygon.

64. The process of claim 59 wherein the vector data is border vector data derived from the intersection of at least one plane offset from at least one slicing plane spaced along a slicing axis, with at least one polygon.

65. The process of claim 59 further including a post-processing step wherein the CAD/CAM data is converted into vector data for producing an oversized reproduction of an object, which reproduction is sanded down in said post-processing step.

66. The process of claim 59 further including a post-processing step wherein the CAD/CAM data is converted into vector data for producing an undersized reproduction of an object, which reproduction is coated with liquid photopolymer and cured in said post-processing step.

67. The process of claim 59 wherein the vector data is the average of the vector data of claims 65 and 66, and the reproduction is not filled or sanded in a post-processing step.

68. The process of claim 59 wherein the vector data is descriptive of vectors, each having a head and a tail endpoint, a direction pointing from the tail to the head endpoint, and includes vector orientation information.

69. The process of claim 68 wherein the converting step includes the substeps of generating vector data which is border vector data, and ordering the data so that the vectors represented by the data are placed in a loop.

70. The process of claim 68 wherein the converting step includes the substeps of:

overlaying the border vector data with spaced paths;

at each point where a path intersects at least one border vector;

performing a selected one of initiating the generation of a selected one of a hatch vector and a skin vector, stopping the generation of a selected one of a hatch vector and a skin vector, and continuing the generation as is, as determined at least partly by the vector orientation information of the at least one border vector which is intersected.

71. The process of claim 59 wherein the vector data is hatch vector data which is descriptive of hatch vectors pointing in a selected one of the X-direction, the Y-direction, both the X- and Y-directions, and directions which are 60 degrees and 120 degrees to the X-direction.

72. The process of claim 59 wherein the vector data is skin vector data which is descriptive of skin vectors pointing in a selected one of the X-direction, and the Y-direction.

73. The process of claim 59 wherein the converting step includes the substep of compensating for a cure width induced by the laser.

74. The process of claim 68 wherein the vector data comprises at least some vector data, and the compensation substep comprises selectively offsetting the endpoints of the border vectors to compensate for cure width.

75. The process of claim 74 wherein the compensating substep further includes the substeps of ordering the border vector data so that the vectors represented by the data form a loop;

and

successively offsetting each endpoint of the border vectors in the loop to displace the vectors by approximately one-half the cure width in a direction of determined by the vector orientation information of the border vectors;

recalculating the border vectors after each offsetting substep, and performing a pairwise comparison of the border vectors in the loop to detect a crossover; and

if a crossover is detected, selectively backing off the offsetting of the endpoints until the crossover is eliminated.

76. The process of claim 73 wherein the compensating substep further includes automatically measuring the beam profile and deriving the cure width for use in beam width compensation.

77. A system for producing a three-dimensional object comprising:

means for deriving data descriptive of cross-sections of the object from data descriptive of the object, at least one of the cross-sections having a boundary encircling an internal portion, by first generating data descriptive of the boundary of the at least one cross-section, which includes boundary orientation information, from the object descriptive data, and then generating data descriptive of the internal portion of the at least one cross-section from the boundary descriptive data and the boundary orientation information;

a container for containing a material capable of selective physical transformation upon exposure to synergistic stimulation;

means for forming successive layers of the material;

means for producing the synergistic stimulation;

means for selectively exposing the layers of the material to the synergistic stimulation in accordance with the data descriptive of the cross-sections to successively form object cross-sections; and

control means for controlling the deriving means, the forming means, and the selective exposing means to produce said object from said successively formed object cross-sections.

78. A method for producing a three-dimensional object comprising the steps of:

driving data descriptive of cross-sections of the object from data descriptive of the object, including deriving first data descriptive of a down-facing region and second data descriptive of a non-down-facing region within at least one cross-section;

containing a material capable of selective physical transformation upon exposure to synergistic stimulation;

associating the data descriptive of the cross-sections with building parameters, including associating the first data with first building parameters, and the second data with second building parameters, wherein the first building parameters may differ from the second building parameters;

successively forming layers of the material;

producing synergistic stimulation;

selectively exposing the layers of the material to the synergistic stimulation in accordance with the data descriptive of the cross-sections, and in accordance with the associated building parameters, to generate successive object cross-sections; and

producing said object from said successively formed object cross-sections;

whereby said at least one object cross-section is formed in said object with a down-facing region and a non-down-facing region, the down-facing region being formed with first characteristics determined by sai first building parameters, the non-down facing region being formed with second characteristics determined by said second building parameters which may differ from said first characteristics.

79. A method for producing a three-dimensional object comprising:

deriving data descriptive of cross-sections of the object from data descriptive of the object, said data including a plurality of datum, and each datum comprising at least a beginning endpoint and an ending endpoint and representing a path to be taken by a beam of synergistic stimulation between the beginning and ending endpoints;

producing said beam of said synergistic stimulation;

containing, at least in part, material capable of selective physical transformation upon exposure to the beam of synergistic stimulation;

successively producing layers of said material;

selectively exposing said layers of said material to said beam of synergistic stimulation in accordance with said data descriptive of said cross-sections of said object, to successively form object cross-sections, the beginning and ending endpoints of each datum included in said plurality being derived before the beam of synergistic stimulation begins tracing the path represented by that datum; and

utilizing said data descriptive of said cross-sections to control said successive producing and selective exposing steps set forth above to produce said three-dimensional object comprising said successively formed object cross-sections.

80. The method of claim 79, wherein said data descriptive of said object comprises at least some polygons having vertices substantially spanning a surface of the object, and said deriving step includes the substep of rounding at least some of said vertices to slicing planes spaced along a slicing axis.

81. The method of claim 79, wherein said data descriptive of said object comprises at least some polygons having vertices substantially spanning a surface of the object, and said deriving step includes the substep of rounding at least some of said vertices to planes offset from slicing planes spaced along a slicing axis.