SOLID IMAGING APPARATUS AND METHOD

• US 20080169589A1
• Filed: 09/17/2007
• Published: 07/17/2008
• Est. Priority Date: 01/17/2007
• Status: Active Grant

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Inventors: Gregory, Richard O., Hull, Charles W., Sperry, Charles R., Scott, Suzanne M., McNamara, Dennis F., Mojdeh, Mehdi, Pappas, William J., Partanen, Jouni
• Granted Patent: US 7,614,866 B2
• Time in Patent Office: Days
• US Class Current: 264/494
• CPC Class Codes: B29C 64/106 using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
• CPC Class Codes: B29C 64/35 Cleaning
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor

Abstract

A solid imaging apparatus is provided that includes a replaceable cartridge containing a source of build material and an extendable and retractable flexible transport film for transporting the build material layer-by-layer from the cartridge to the surface of a build in an image plane. An operator using the device needs merely to remove a spent cartridge and replace it with a fresh cartridge to continue solid imaging virtually uninterrupted. The apparatus also includes the capability of withdrawing and inserting an imager without the operator having to perform a separate alignment step. A brush attached to the transport film and forming part of the cartridge provides for intra-layer removal of excess uncured build material. If desired, the apparatus can produce a fully reacted build. A high intensity UV source cures the build between layers. An injection molded build pad is designed to hold a build in an inverted position for improving the build. The invention also provides for tilting the build elevator to reduce air entrainment and for releasing the build from the image plane.

Claims

1. A solid imaging apparatus for creating a build layer-by-layer, said apparatus comprising:

a) an image plane assembly comprising a rigid surface transparent to solid imaging radiation;

b) a build platform located adjacent to said rigid transparent surface on one side thereof for receiving a build pad and supporting a build thereon, said build platform elevatingly disposed with respect to said rigid transparent surface;

c) at least one source of solid imaging radiation for illuminating said rigid transparent surface opposite said build platform;

d) an elevator for moving said build platform with respect to said rigid transparent surface;

e) a cartridge comprising;

(i) a cartridge housing;

(ii) a source of solid imaging build material contained in said cartridge housing; and

(iii) an extendable and retractable reciprocating transport surface contained in said cartridge housing and transparent to solid imaging radiation for transporting build material layer-by-layer from said source of build material to said image plane between said build platform and said rigid transparent surface, whereby said elevator moves said build platform for supporting a build and build pad into and out of solid imaging contact with the build material on said transport surface for illumination from said at least source of solid imaging radiation through said rigid surface and said transport surface; and

f) a controller in controlling communication with said apparatus, whereby a build is alternately coated and imaged with layers of solid imaging build material.

2. The apparatus of claim 1 wherein said at least one source of solid imaging radiation comprises an imager source selected from the group consisting of laser scanners, ultraviolet projectors, liquid crystal display projectors, light emitting diode projectors, liquid crystal on silicon projectors, digital light processing projectors, and combinations of one or more of these projectors.

3. Apparatus of claim 2 further comprising a supporting frame for said imager and wherein said imager comprises an imager housing, said supporting frame and said imager housing having corresponding alignment fixtures whereby said imager is imagingly aligned for imaging a build.

4. Apparatus of claim 1 wherein said cartridge further comprises an extendable and retractable cleaning assembly for removing excess uncured build material from a build surface, said cleaning assembly affixed to said transport surface at a leading end thereof.

5. Apparatus of claim 4 wherein said cleaning assembly comprises a rotatable brush contained in a brush housing.

6. Apparatus of claim 5 wherein said brush housing further comprises one or more seals for sealing said cleaning assembly within said cartridge housing, thereby substantially precluding ingress of radiation and egress of build material.

7. The apparatus of claim 4 further comprising at least one source of ultraviolet (“

UV”

) radiation sufficient to provide a secondary cure of a build.

8. The apparatus of claim 7 wherein said source of UV radiation sufficient to provide a secondary cure of a build provides from about 0.5 to 3 J/cm2.

9. The apparatus of claim 7 wherein said build platform and the build pad allow ultraviolet radiation to reach the build and said apparatus further comprises at least a halo source of ultraviolet radiation for secondary cure of the vertical surfaces of a build and a hood source of ultraviolet radiation for secondary cure of a build located opposite said platform from said image plane.

10. The apparatus of claim 1 further comprising mirrors for folding the image from said imaging source for illuminating said rigid transparent surface.

11. The apparatus of claim 1 further comprising a pair of mirrors for folding the image from said imaging source for illuminating said rigid transparent surface, one of which pair of mirrors receives the image from said imager and transmits the image to the other mirror, the other mirror in turn transmitting the image for illuminating said rigid transparent surface.

12. The apparatus of claim 11 wherein said other mirror is a reciprocating mirror.

13. Apparatus of claim 1 further comprising a vacuum source in vacuum communication between said transport surface and said rigid transparent surface.

14. Apparatus of claim 1 further comprising a vacuum source in vacuum communication with said build platform for retaining a build pad thereon.

15. Apparatus of claim 1 wherein said elevator comprises independent drives on at least two sides of said build platform.

16. Apparatus of claim 15 wherein said elevator further comprises a compression switch for registration of said build platform parallel to said rigid transparent surface.

17. Apparatus of claim 16 wherein said elevator further comprises a homing switch to indicate that the build platform has reached its uppermost limit.

18. Apparatus of claim 1 further comprising a housing for said image plane assembly, radiation source, build platform, and cartridge.

19. Apparatus of claim 1 wherein said rigid transparent surface is a sheet of glass having an upper and a lower surface and said image plane assembly further comprises a supporting frame having upper and lower surfaces for said glass sheet, said glass sheet supporting frame comprising a vacuum path for vacuum communication from a source thereof to the upper surface of said glass sheet, said frame supporting said upper surface of said glass sheet sufficiently below said upper surface of said frame to retain said transport surface.

20. Apparatus of claim 19 wherein said frame comprises slopes at opposite ends thereof for engaging said transport surface.

21. Apparatus of claim 1 further comprising a motor for extending said transport surface from said cartridge and a motor for retracting said transport surface.

22. Apparatus of claim 21 wherein said transport surface comprises a pull strap connected to a leading edge of said transport surface and said apparatus further comprises a tractor for extending said transport surface by pulling said strap across said rigid transparent surface and a solenoid poppet for lifting said transport surface off said rigid transparent surface.

23. A method for solid imaging to produce three-dimensional objects, said method comprising the steps of:

a) transporting a layer of solid imaging build material from a source thereof to an image plane;

b) contacting a build surface with the layer of build material;

c) imaging the layer in the image plane to solidify imaged portions of the layer onto the build surface;

d) returning uncured build material remaining on the transport surface to source thereof; and

e) repeating steps (a) through (d) to produce three-dimensional object.

24. The method of claim 23 further comprising the steps of removing excess uncured build material from the build surface after imaging the layer and irradiating the imaged layer with ultraviolet light.

25. The method of claim 23 wherein the step of contacting a build surface with the layer of build material comprises tilting the build on approaching the layer and the method further comprises the step of tilting and removing the build after imaging the layer.