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

• US 5,174,931 A
• Filed: 04/27/1990
• Issued: 12/29/1992
• Est. Priority Date: 09/26/1988
• Status: Expired due to Term

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Inventors: Lewis, Mark A., Almquist, Thomas A., Lewis, Charles W., Liran, Abraham, Jacobs, Paul F., Modrek, Borzo
• Primary Examiner(s): Tentoni, Leo B.
• Application Number:
  US07/515,479
• Time in Patent Office: 977 Days
• Field of Search: 264/22, 264/40.1, 264/40.2, 264/236, 264/308, 264/347, 425/135, 425/140, 425/141, 425/147, 425/162, 425/174, 425/174.4, 156/64, 156/272.8, 156/273.3, 156/273.5, 156/275.5, 156/307.1, 156/378, 156/379.6, 156/538, 427/8, 427/53.1, 427/54.1, 427/356, 427/358, 118/100, 118/120, 118/407, 118/413, 118/421, 118/423, 118/429, 118/620, 118/693, 118/694, 118/720, 118/500, 73/293, 73/305, 73/312, 73/317, 73/319, 73/320, 73/322.5, 250/432 R, 250/492.1, 250/577, 340/619, 340/623, 340/624, 340/625
• US Class Current: 264/401
• 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 64/135 the energy source being concentrated, e.g. scanning lasers or focused light sources
• CPC Class Codes: G01F 23/2921 for discrete levels
• CPC Class Codes: G01F 23/366 using optoelectrically actuated indicating means
• CPC Class Codes: G05D 9/12 characterised by the use of electric means
• CPC Class Codes: Y10T 156/17 Surface bonding means and/or assemblymeans with work feeding or handling means

Abstract

Apparatus and methods for stereolithographically forming a three-dimensional object includes a vessel for holding a building material and a smoothing member for forming a uniform coating over a previously formed layer of the object. The smoothing member has a plurality of blades. The smoothing member is swept over a previously formed layer of the object, in at least two directions. Different clearances between the lower surface of the smoothing member and the upper surface of the previously formed layer are used to provide a uniform coating for a subsequent layer over the previously formed layer. The sweeping velocity of the smoothing member can be varied. Retractable needles are attached to the smoothing member for adjusting a blade gap between the lower surface of the smoothing member and the surface of the building material.

Claims

1. An apparatus for stereolithographically forming a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object is formed over a previously formed layer of the object, comprising:

a) a vessel for holding a building material having a working surface and the building material selectively physically transformable upon exposure to prescribed synergistic stimulation;

b) means for forming a uniform coating of desired thickness over the previously formed layer, including;

a smoothing element having a plurality of substantially separate members on a lower surface thereof;

means for sweeping the smoothing members over the previously formed layer; and

c) means for applying a prescribed pattern of synergistic stimulation to the building material at the working surface to form the subsequent layer.

2. The apparatus of claim 1 further comprising means for holding the working surface substantially constant.

3. The apparatus of claim 1 wherein the smoothing element comprises a winged element.

4. The apparatus of claim 1 wherein the smoothing element comprises a trident blade.

5. An apparatus for stereolithographically forming a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object is formed over a previously formed layer of the object, comprising:

a) a vessel for holding a building material having a working surface and the building material selectively physically transformable upon exposure to prescribed synergistic stimulation;

b) means for forming a uniform coating over the previously formed layer, including;

a smoothing member;

means for sweeping the smoothing member in a direction different from a direction of sweeping during a previous sweep of the smoothing member; and

c) means for applying a prescribed pattern of synergistic stimulation to the building material at the working surface to form the subsequent layer.

6. The apparatus of claim 5 further comprising means for holding the working surface substantially constant.

7. The apparatus of claim 5 further comprising means for forming a uniform coating over a second previously formed layer in preparation for forming a second subsequent layer of the object, including means for sweeping the smoothing member wherein the different direction of sweeping occurs during the uniform coating process over the second previously formed layer.

8. An apparatus for stereolithographically forming a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object having a layer thickness is formed over a previously formed layer of the object, comprising:

a) means for holding a volume of building material having a working surface wherein the building material is capable of selective transformation upon exposure to prescribed synergistic stimulation;

b) means for forming a uniform coating over the previously formed layer including means for sweeping a smoothing member over the previously formed layer with a value of a clearance between a lower surface of the smoothing member and an upper surface of the previously formed layer which is different from the layer thickness; and

c) means for applying a prescribed pattern of synergistic stimulation to the building material at the desired working surface to transform at least a portion of the building material to form the subsequent layer.

9. The apparatus of claim 8 wherein the means for forming a uniform coating further comprises:

a) means for sweeping a smoothing member a first time over the previously formed layer with a first value of a clearance between a lower surface of the smoothing member and an upper surface of the previously formed layer;

means for sweeping the smoothing member a second time over the previously formed layer with a second value of a clearance between the lower surface of the smoothing member and the upper surface of the previously formed layer; and

c) means for causing the first and second values of clearance to be different and at least one of the first and second values of clearance to be different from the layer thickness.

10. The apparatus of claim 8 further comprising means for holding the working surface substantially constant.

11. An apparatus for stereolithographically forming at least a portion of a three-dimensional object wherein at least a first subsequent layer and a second subsequent layer of the three-dimensional object are formed over a first and second previously formed layer of the object, respectively, comprising:

a) means for holding a volume of building material having a working surface wherein the building material is capable of selective transformation upon exposure to prescribed synergistic stimulation;

b) means for forming a unfirm coating of desired thickness over the previously formed layer in preparation for forming the first subsequent layer of the three-dimensional object including means for sweeping a smoothing member over the first previously formed layer at least once with a first smoothing member velocity;

c) means for applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the first subsequent layer;

d) means for forming a uniform coating of desired thickness over the second previously formed layer in preparation for forming the second subsequent layer of the three-dimensional object including means for sweeping a smoothing member over the second previously formed layer at least once with a second smoothing member velocity;

e) means for causing the first and second smoothing member velocities to be different; and

means for applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the first subsequent layer.

12. The apparatus of claim 11 further comprising means for holding the working surface substantially constant.

13. An apparatus for stereolithographically forming a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object is formed over a previously formed layer of the object, comprising:

a) means for holding a volume of building material having a working surface wherein the building material is capable of selective transformation upon exposure to prescribed synergistic stimulation;

b) means for forming a unfirm coating of desired thickness over the previously formed layer including;

means for sweeping a smoothing member over the previously formed layer at least once with a first smoothing member velocity,

means for sweeping the smoothing member at least once with a second smoothing member velocity,

means for causing the first and second smoothing member velocities to be different; and

c) means for applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the subsequent layer.

14. An apparatus for stereolithographically forming a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object is formed over a previously formed layer of the object, comprising:

a) means for holding a volume of building material having a working surface wherein the building material is capable of selective transformation upon exposure to prescribed synergistic stimulation;

b) means for forming a unfirm coating of desired thickness over the previously formed layer including;

means for sweeping a smoothing member at least once over the previously formed layer with a first value of a clearance between a lower surface of the smoothing member and an upper surface of the previously formed layer,

means for sweeping a smoothing member at least once over the previously formed layer with a second value of a clearance between a lower surface of the smoothing member and the upper surface of the previously formed layer,

means for causing the second value of clearance to be less than the first value of clearance; and

c) means for applying a prescribed pattern of synergistic stimulation to the building material at the desired working surface to transform at least a portion of the building material to form the subsequent layer.

15. The apparatus of claim 14 further comprising means for holding the working surface substantially constant.

16. An apparatus for stereolithographically forming a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object is formed over a previously formed layer of the object, comprising:

a) a vessel for holding a building material having a working surface and selectively transformable upon exposure to prescribed synergistic stimulation;

b) means for forming a unfirm coating of desired thickness over the previously formed layer including;

means for sweeping a smoothing member over the previously formed layer,

adjustment means attached to the smoothing member for adjusting its vertical position,

needles attached to the smoothing member for adjusting a gap between a lower surface of the smoothing member and the working surface; and

c) means for applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the subsequent layer.

17. The apparatus of claim 16 further comprising means for holding the working surface substantially constant.

18. The apparatus of claim 16 wherein the needles are retractable.

19. A method for stereolithographically forming at least a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object is formed over a previously formed layer of the object, comprising the steps of:

a) holding a volume of building material having a working surface wherein the building material is capable of selective transformation upon exposure to prescribed synergistic stimulation;

b) forming a unfirm coating over the previously formed layer including sweeping a smoothing member in a direction different from a direction of sweeping during a previous sweep of the smoothing member; and

c) applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the first subsequent layer.

20. The method of claim 19 wherein the building material is a photopolymer.

21. The method of claim 19 further comprising the step of holding the working surface of the building material substantially constant.

22. A method for stereolithographically forming at least a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object having a layer thickness is formed over a previously formed layer of the object, comprising the steps of:

a) holding a volume of building material having a working surface wherein the building material is capable of selective transformation upon exposure to prescribed synergistic stimulation;

b) forming a unfirm coating of desired thickness over the previously formed layer including sweeping a smoothing member over the previously formed layer with a value of a clearance between a lower surface of the smoothing member and an upper surface of the previously formed layer which is different from the layer thickness; and

c) applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the subsequent layer.

23. The method of claim 22 further comprising the steps of:

sweeping a smoothing member over the previously formed layer a first time with a first value of a clearance between a lower surface of the smoothing member and an upper surface of the previously formed layer; and

sweeping the smoothing member a second time over the previously formed layer with a second value of a clearance between a lower surface of the smoothing member and the upper surface of the previously formed layer.

24. The method of claim 22 wherein the building material is a photopolymer.

25. The method of claim 22 further comprising the step of holding the working surface of the building material substantially constant.

26. A method for stereolithographically forming at least a portion of a three-dimensional object wherein at least a first subsequent layer and a second subsequent layer of the three-dimensional object are formed over a first and second previously formed layer of the object, respectively, comprising the steps of:

a) holding a volume of building material having a working surface wherein the building material is capable of selective transformation upon exposure to prescribed synergistic stimulation;

b) forming a unfirm coating of desired thickness over the previously formed layer in preparation for forming the first subsequent layer of the three-dimensional object, including sweeping a smoothing member over the first previously formed layer at least once with a first smoothing member velocity;

c) applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the first subsequent layer;

d) forming a unfirm coating of desired thickness over the second previously formed layer in preparation for forming the second subsequent layer of the three-dimensional object including sweeping a smoothing member over the second previously formed layer at least once with a second smoothing member velocity different from the first smoothing member velocity; and

c) applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the second subsequent layer.

27. The method of claim 26 wherein the building material is a photopolymer.

28. The method of claim 26 further comprising the step of holding the working surface of the building material substantially constant.

29. A method for stereolithographically forming at least a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object is formed over a previously formed layer of the object, comprising the steps of:

a) holding a volume of building material having a working surface wherein the building material is capable of selective transformation upon exposure to prescribed synergistic stimulation;

b) forming a unfirm coating of desired thickness over the previously formed layer including;

sweeping a smoothing member at least once over the previously formed layer at a first velocity;

sweeping the smoothing member at least once over the previously formed layer at a second velocity;

wherein the first and second velocities are different; and

c) applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the subsequent layer.

30. A method for stereolithographically forming at least a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object is formed over a previously formed layer of the object, comprising the steps of:

a) holding a volume of building material having a working surface wherein the building material is capable of selective transformation upon exposure to prescribed synergistic stimulation;

b) forming a unfirm coating of desired thickness over the previously formed layer including;

sweeping a smoothing member a first time over the previously formed layer with a first value of a clearance between a lower surface of the smoothing member and an upper surface of the formed layer,

sweeping the smoothing member a second time over the previously formed layer with a second value of a clearance between the lower surface of the smoothing member and the upper surface of the previously formed layer, wherein the second value of the clearance is less than the first value of the clearance; and

c) applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the subsequent layer.

31. The method of claim 30 wherein the building material is a photopolymer.

32. The method of claim 30 further comprising the step of holding the working surface of the building material substantially constant.

33. A stereolithography system for forming at least a portion of a three-dimensional object, comprising:

a tank for holding a bath of pulverizable fluid, the bath having an upper surface;

an object support;

means to apply a coating of pulverizable fluid over a surface of a last-formed object layer supported by the object support;

means for displacing the coating over the surface of the last-formed object layer above the upper surface of the bath of pulverizable fluid;

means to strike off excess pulverizable fluid from the applied coating to provide a smoothed layer of pulverizable fluid of desired thickness over the surface of the last-formed object layer; and

means to apply a curing media in a predetermined pattern to the smoothed layer of pulverizable fluid to form a next object layer;

whereupon said portion of said three-dimensional object is provided comprising said next object layer situated over the surface of the last-formed object layer.

34. The stereolithography system of claim 33 wherein the means to strike off is a doctor blade.

35. The stereolithography system of claim 34 further comprising means to move the doctor blade in a horizontal plane.

36. A method of forming at least a portion of a three-dimensional object, comprising the steps of:

holding a bath of pulverizable fluid in a tank, the bath having an upper surface;

applying a layer of said polymerizable fluid over a surface of a last-formed object layer supported by a support;

moving the support to displace said layer of said polymerizable fluid applied over said surface of said last-formed object layer above the upper surface of said bath;

smoothing the layer of polymerizable fluid on said surface of said last-formed object layer to a desired thickness by striking off any excess polymerizable fluid from the applied layer; and

applying a curing media in a preselected pattern onto the smoothed layer of polymerizable fluid to sufficiently cure the layer so that it forms a next layer of the object;

whereupon said portion of said three-dimensional object is provided comprising said next layer of said object situated over the surface of the last-formed layer of said object.

37. The method of claim 36 wherein the curing media is radiation selected from the group consisting of ultraviolet radiation, infrared radiation, visible light, electron beams, x-rays, and gamma rays.

38. The method of claim 37 wherein the polymerizable fluid is curable with ultraviolet radiation and the curing media is ultraviolet radiation.

39. The method of claim 36 wherein the layer of polymerizable fluid is applied to said surface of said last-formed object layer supported by the support by submerging the surface into the bath of polymerizable fluid.

40. The method of claim 36 wherein the applied layer of polymerizable fluid is raised out of the bath and excess polymerizable fluid is struck off by means of a horizontally moving doctor blade to form a smoothed layer of polymerizable fluid of the desired thickness on said surface of said last-formed object layer.

41. The method of claim 36 wherein the support is lowered into the bath after the layer of polymerizable fluid is smoothed so that the surface of the smoothed layer of polymerizable fluid is coincident with the bath surface.

42. The method of claim 41 wherein after the surface of the smoothed layer of polymerizable fluid is at the level of the bath surface, the smoothed layer is subjected to curing media.

43. The method of claim 42 wherein after the smoothed layer is subjected to curing media, the support is further lowered into the bath of polymerizable fluid so that a subsequent layer of polymerizable fluid can flow onto said next layer of said object.

44. The method of claim 36 wherein a plurality of thin layers of polymerizable fluid are applied, leveled, and cured to form a three-dimensional object.

45. The method of claim 36 wherein the curing media is ultraviolet radiation emitted from a HeCd laser at a wavelength between approximately 300 to 350 nanometers and from about 10 to about 30 milliwatts of power.

46. The method of claim 40 wherein the doctor blade moves at a speed of from about 0.25 to about 10 inches per second.

47. The method of claim 36 wherein the thickness of the layer of polymerizable fluid which is polymerized by the application thereto of curing media ranges from about 0.005 to about 0.04 inch.

48. A stereolithographically system for forming at least a portion of a three-dimensional object comprising a next layer of the three-dimensional object situated over a previously formed layer, said next layer having a desired thickness and said previously formed layer having an upper surface, comprising:

a) means for holding a volume of building material;

b) means to apply a coating of building material, said coating including excess material over at least a portion of the upper surface of the previously formed layer of the object;

c) means for displacing the previously formed layer relative to a desired working surface so that the upper surface of the previously formed layer is positioned above a level which is below the desired working surface by the desired thickness of the next layer;

d) means to displace material of said coating of building material to provide a smooth coating of building material of the desired thickness over the previously formed layer, while the upper surface of the previously formed layer is positioned above the level which is below the desired working surface by the desired thickness of the next layer;

e) means for relatively positioning the upper surface of the previously formed layer to be substantially at the level which is below the desired working surface by the desired thickness of the next layer; and

f) means for applying a prescribed pattern of synergistic stimulation to the building material at the desired working surface in order to transform at least a portion of the building material, whereby the next layer is formed over the previously formed layer.

51. The stereolithography system of claim 48 further comprising at least one computer control system for controlling at least one of the means for applying the prescribed pattern and the means for displacing.

49. A method for stereolithographically forming at least a portion of a three-dimensional object comprising a next layer of the three-dimensional object situated over a previously formed layer of said object, comprising the steps of:

a) holding a volume of building material capable of selective physical transformation upon exposure to prescribed synergistic stimulation;

b) forming a uniform coating of desired thickness over the previously formed layer including sweeping a smoothing member at least twice above the previously formed layer; and

c) applying a prescribed pattern of synergistic stimulation to the building material at the desired working surface in order to transform at least a portion of the building material, whereby said portion of said three-dimensional object is formed comprising the next object layer formed over the previously formed layer.

50. A method for stereolithographically forming at least a portion of a three-dimensional object comprising a next layer of the three-dimensional object situated over a previously formed layer of said object, comprising the steps of:

a) holding a volume of building material capable of selective physical transformation upon exposure to prescribed synergistic stimulation;

b) forming a uniform coating of desired thickness over the previously formed layer including sweeping a smoothing member at least once above the previously formed layer; and

c) applying a prescribed pattern of synergistic stimulation to the building material at a desired working surface in order to transform at least a portion of the building material, whereby the next object layer is formed over the previously formed layer after waiting at least for the smoothing member to complete sweeping across the previously formed layer;

whereby said portion of said three-dimensional object is formed comprising said next layer situated over the previously formed layer.

52. A stereolithographically system for forming at least a portion of a three-dimensional object comprising a next layer of the three-dimensional object situated over a surface of a previously formed layer of the object, comprising:

a) means for holding a quantity of building material capable of selective physical transformation upon exposure to synergistic stimulation;

b) means for forming a uniform coating of material over the previously formed layer including a sweepable member having a lower edge which sweeps out a plane above a plane of a desired working surface; and

c) means for selectively applying a prescribed pattern of synergistic stimulation to the building material at the desired working surface in order to transform at least a portion of the building material, whereby said portion of said three-dimensional object is formed comprising said next object layer formed over said previously formed layer.

53. A stereolithography system for forming at least a portion of a three-dimensional object, comprising:

a container for holding a volume of material capable of physical transformation upon exposure to synergistic stimulation;

an object support;

means to apply a coating of said material over a surface of a last-formed object layer supported by the object support;

means for relatively displacing the last-formed object layer so that said coating when applied is displaced above a desired working surface;

means to displace material in the applied coating, when said coating is displaced above said desired working surface, to provide a smoothed layer of material of desired thickness over the surface of the last-formed object layer; and

means to apply said synergistic stimulation in a predetermined pattern to the smoothed layer of material while the upper surface of the smoothed layer is located at the desired working surface to form a next object layer;

whereupon said portion of said object is provided comprising said next object layer situated over the surface of the last-formed object layer.

54. A method of forming at least a portion of a three-dimensional object, comprising the steps of:

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

applying a layer of said material over a surface of a last-formed object layer supported by a support;

relatively displacing said last-formed object layer so that said layer when applied is displaced above a desired working surface;

smoothing said displaced layer of material to a desired thickness by displacing material from the layer to provide a smoothed layer; and

applying said synergistic stimulation in a prescribed pattern onto the smoothed layer of material to sufficiently transform the layer so that it forms a next layer of the object;

whereupon said portion of said three-dimensional object is provided comprising said next object layer situated over said surface of said last-formed object layer.