Solid imaging method and apparatus

• US 5,236,812 A
• Filed: 01/02/1991
• Issued: 08/17/1993
• Est. Priority Date: 12/29/1989
• Status: Expired due to Fees

• Current Assignee: DSM B.V.
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Chamberlin, Bruce A., Vassiliou, Eustathios, Lawton, John A.
• Primary Examiner(s): Bowers, Jr., Charles L.
• Assistant Examiner(s): Chea, Thorl
• Application Number:
  US07/636,869
• Time in Patent Office: 958 Days
• Field of Search: 430/269, 430/320, 430/394, 430/396, 430/327, 430/331, 430/945, 430/935, 156/58, 156/59, 264/22
• US Class Current: 430/327
• CPC Class Codes: B29C 64/135 the energy source being concentrated, e.g. scanning lasers or focused light sources
• CPC Class Codes: B29K 2995/0073 smooth
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing

Abstract

An apparatus and method for fabricating integral three-dimensional objects from contiguous layers of a photosensitive composition in an imagewise manner, with an additional photogelled portion or photohardened wall, or both, surrounding the three-dimensional object.

Claims

1. A method for fabricating an integral three-dimensional object from a multiplicity of cross sectional portions of the object, the cross sectional portions corresponding to photohardened portions of contiguous layers of a photogellable and photohardenable liquid composition, comprising the steps of:

(a) forming a layer of the photohardenable liquid composition;

(b) providing a first exposure of actinic radiation to the layer, adequate to produce a soft gelled area, the soft gelled area surrounding a respective cross sectional portion of the object;

(c) providing imagewise a second exposure of actinic radiation to the cross sectional portion of the object, adequate to imagewise photoharden said portion;

(d) introducing a new layer of photohardenable liquid composition onto the layer subjected to steps (b) and (c);

(e) repeating steps (b) to (d) until all layers of the three dimensional object have been photohardened and all soft gelled areas have formed a soft gelled mass surrounding the three dimensional object, the object being separated from the gelled mass by an interface; and

(f) removing the soft gelled mass in order to recover the three dimensional object.

2. A method as defined in claim 1, further comprising the step of providing a third exposure of actinic radiation to the periphery of the gelled area, after step (a) and before step (d), the third exposure being adequate to photoharden a complete sector of a circumferencial wall, the wall being built to contain the gelled area.

3. A method as defined in claim 1, wherein the first exposure of step (b) is repeatable flood exposure.

4. A method as defined in claim 2, wherein the first exposure is repeatable flood exposure.

5. A method as defined in claim 2, wherein the third exposure is repeatable flood exposure.

6. A method as defined in claim 1 or 2, further comprising the step of providing a fourth exposure of actinic radiation at the interface of the object and the gelled area, said fourth exposure being lower than the first exposure.

7. A method as defined in claim 1 or 2, wherein the layers are formed by curtain coating.

8. A method as defined in claim 1 or 2, wherein the layers are formed by extrusion.

9. A method as defined in claim 1 or 2, wherein the layers are formed by spraying.

10. A method as defined in claim 1 or 2, wherein the layers are leveled by doctoring.

11. A method as defined in claim 1 or 2, wherein the photohardenable composition comprises a plastisol.

12. A method as defined in claim 11, further comprising the step of heat treating the three dimensional object.

13. A method for fabricating an integral three-dimensional object from a multiplicity of cross sectional portions of the object, the cross sectional portions corresponding to photohardened portions of contiguous layers of a photohardenable liquid composition, comprising the steps of:

(a) forming a layer of the photohardenable liquid composition;

(b) forming a complete sector of a peripheral wall of photohardened composition around the respective cross sectional portion of the three-dimensional object by first exposing said complete sector of the peripheral wall to radiation by flood exposure;

(c) providing imagewise a point-by-point exposure of actinic radiation to the cross sectional portion of the object, adequate to imagewise photoharden said cross sectional portion;

(d) introducing a new layer of photohardenable liquid composition onto the layer subjected to steps (b) and (c); and

(e) repeating steps (b) to (d) until all layers of the three dimensional object and all sectors of the peripheral wall have been photohardened.

14. A method as defined in claim 13, wherein the layers are formed by curtain coating,

15. A method as defined in claim 13, wherein the layers are formed by extrusion.

16. A method as defined in claim 13, wherein the layers are formed by spraying.

17. A method as defined in claim 13, wherein the layers are leveled by doctoring.

18. A method as defined in claim 13, wherein the photohardenable composition comprises a plastisol.

19. A method as defined in claim 18, further comprising the step of heat treating the three dimensional object.

20. A method of fabricating a three-dimensional object comprising the steps of:

(a) forming a layer of photohardenable liquid composition;

(b) providing imagewise a first exposure of actinic radiation to the layer, said first imagewise exposure representing a respective cross-sectional portion of the object, and said first imagewise exposure adequate to photoharden the portion imagewise;

(c) providing a second imagewise exposure of actinic radiation to the layer, said second imagewise exposure representing a respective cross-sectional segment of a support region, said second imagewise exposure being adequate to photoharden the segment imagewise, and said segment being separated from the object portion by a gap;

(d) forming a new layer of photohardenable liquid composition on the layer subjected to steps (b) and (c);

(e) repeating steps (b) through (d) until all portions of the object and all segments of the regions have been formed.