Layer manufacturing using electrostatic imaging and lamination

• US 6,376,148 B1
• Filed: 01/17/2001
• Issued: 04/23/2002
• Est. Priority Date: 01/17/2001
• Status: Expired due to Fees

• Current Assignee: Nanotek Instruments Group, LLC
• Original Assignee: Nanotek Instruments, Inc.
• Inventors: Liu, Jun Hai, Jang, Bor Zeng
• Primary Examiner(s): GOODROW, JOHN L
• Application Number:
  US09/764,025
• Time in Patent Office: 461 Days
• Field of Search: 430/11, 430/14, 430/15, 430/18, 430/22, 430/97, 430/124, 156/273.1, 425/174.8 E
• US Class Current: 430/124.4
• CPC Class Codes: B22F 10/14 by jetting of binder onto a bed of metal powder
• CPC Class Codes: B22F 10/32 of the atmosphere, e.g. composition or pressure in a building chamber
• CPC Class Codes: B22F 12/13 to preheat the material
• CPC Class Codes: B22F 12/41 characterised by the type, e.g. laser or electron beam
• CPC Class Codes: B22F 12/50 Means for feeding of material, e.g. heads
• CPC Class Codes: B22F 12/90 Means for process control, e.g. cameras or sensors
• CPC Class Codes: B29C 64/40 Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof
• 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: B33Y 70/00 Materials specially adapted for additive manufacturing
• CPC Class Codes: B33Y 70/10 Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
• CPC Class Codes: G03G 13/22 Processes involving a combination of more than one step according to groups G03G13/02 - G03G13/20 G03G13/01 takes precedence
• CPC Class Codes: G03G 15/224 Machines for forming tactile or three dimensional images by electrographic means, e.g. braille, 3d printing
• CPC Class Codes: G05B 19/4099 Surface or curve machining, making 3D objects, e.g. desktop manufacturing
• CPC Class Codes: G05B 2219/49013 Deposit layers, cured by scanning laser, stereo lithography SLA, prototyping
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

A solid freeform fabrication method and related apparatus for fabricating a three-dimensional object from successive layers of a primary body-building powder material and a binder powder in accordance with a computer-aided design of the object, the method including: (a) providing a work surface; (b) feeding a first layer of the primary body-building powder material to the work surface; (c) operating an electrophotographic powder deposition device to create a binder powder image in accordance with this design; (d) transferring this binder powder image to the first layer of body-building powder; (e) applying energy sources to fuse the binder powder, forming a binder fluid to permeate through the first layer of body-building powder for bonding and consolidating the powder particles to form a first cross-section of the object; (f) feeding a second layer of the primary body-building powder onto the first layer and repeating the operating, transferring, and applying steps to form a second cross-section of the object; (g) repeating the feeding, operating, transferring, and applying steps to build successive layers in a layer-wise fashion in accordance with the design for forming the multiple-layer object; and (h) removing un-bonded powder particles, causing the 3-D object to appear.

Claims

1. A solid freeform fabrication method for fabricating a three-dimensional object from successive layers of a primary body-building powder material and a binder powder in accordance with a computer-aided design of the object, said method comprising:

(a) providing a work surface;

(b) feeding a first layer of said primary body-building powder material to said work surface;

(c) operating an electrophotographic powder deposition means to create a transferable binder powder image in accordance with said design;

(d) transferring said transferable binder powder image to said first layer of primary body-building powder material;

(e) applying energy means to fuse said binder powder, forming a binder fluid to permeate through said first layer of primary body-building material for bonding and consolidating the powder particles in said first layer to form a first cross-section of said object;

(f) feeding a second layer of said primary body-building powder material onto said first layer and repeating the operating, transferring, and applying steps to form a second cross-section of said object;

(g) repeating the feeding, operating, transferring, and applying steps to build successive layers in a layer-wise fashion in accordance with said design for forming multiple layers of said object; and

(h) removing un-bonded powder particles in said multiple layers, causing said 3-D object to appear.

2. A method for fabricating a three-dimensional object as set forth in claim 1, wherein said steps of applying energy means comprise pre-heating a layer of primary body-building powder material to a temperature above the melting point of said binder powder.

3. A method for fabricating a three-dimensional object as set forth in claim 1, wherein said binder powder comprises a resin composition that can be cured or hardened with heat, ultra violet light, electron beam, ion beam, plasma, microwave, X-ray, Gamma ray, or a combination thereof.

4. A method for fabricating a three-dimensional object as set forth in claim 1, wherein said steps of applying energy means are carried out in such a manner that said successive layers are affixed together to form a unitary body of said 3-D object.

5. A method for fabricating a three-dimensional object as set forth in claim 1, wherein said fused binder fluid is allowed to solidify once permeating through the gaps between powder particles of a layer of primary body-building material.

6. A method for fabricating a three-dimensional object as set forth in claim 1, wherein said electrophotographic powder deposition means comprises devices selected from the group consisting of a corona discharging device, capacitor dot matrix charging device, thin photoconductive layer, scanning laser imaging device, charge cleaning device, and combinations thereof.

7. A method for fabricating a three-dimensional object as set forth in claim 1, wherein said primary body-building powder material is selected from the group consisting of fine polymeric, glassy, metallic, ceramic, and carbonaceous particles, and combinations thereof.

8. A method for fabricating a three-dimensional object as set forth in claim 7, wherein said powder further comprises ingredients for imparting desired physical or chemical properties to said 3-D object.

9. A method for fabricating a three-dimensional object as set forth in claim 1, comprising the further steps of:

providing a control means operably connected to said electro-photographic powder deposition means; and

supplying the control means with design data including the boundaries of each cross-sectional region of said object.

10. A method for fabricating a three-dimensional object as set forth in claim 1, comprising the further steps of:

providing a control means having a computer; and

supplying the overall dimensions of the object to the computer, the computer determining the boundaries of each cross-sectional region of the object.

11. A method for fabricating a three-dimensional object as set forth in claim 1, wherein said feeding of powder layers is accomplished by using a dispensing means comprising a rotating drum.

12. A method for fabricating a three-dimensional object as set forth in claim 1, wherein the powder feeding step comprises the steps of:

positioning a powder-dispensing means at a predetermined initial distance from said work surface;

operating and moving said powder-dispensing means relative to said work surface along selected directions in an X-Y plane to dispense and deposit a thin layer of powder on said work surface, said X-Y plane of an X-Y-Z Cartesian coordinate being defined to be substantially parallel to said work surface and the Z-axis being perpendicular to said X-Y plane; and

after a cross-section of said object is built in said layer, moving said work surface away from said powder-dispensing means along said Z-direction by a predetermined distance to allow for the feeding and building of a subsequent layer.

13. A method as defined in claim 1, further comprising the steps of:

creating a geometry of said three-dimensional object on a computer with said geometry including a plurality of data points defining the object;

generating programmed signals corresponding to each of said data points in a predetermined sequence; and

operating said electro-photographic powder deposition means and moving said work surface relative to said electro-photographic powder deposition means in response to said programmed signals.

14. A method as defined in claim 1, further comprising the steps of:

creating a geometry of said three-dimensional object on a computer with said geometry including a plurality of layer-wise data sets defining the object;

each of said data sets being coded with a selected powder material composition;

generating programmed signals corresponding to each of said data sets in a predetermined sequence;

for each layer to be built, operating a powder-dispensing means to feed a current powder layer of said selected powder material composition onto said work surface or a previously fed layer;

operating said electro-photographic powder deposition means in response to said programmed signals to create a binder powder image and transfer said binder powder image onto said current layer to bond and consolidate a cross-section of said object in said layer; and

repeating said steps of operating a powder-dispensing means and said electro-photographic powder deposition means to build a multi-material 3-D object.

15. A method as defined in claim 1, further comprising

using dimension sensor means to periodically measure dimensions of the object being built;

and

using a computer to determine the thickness and outline of individual layers of powder materials in accordance with a computer aided design representation of said object;

said computing step comprising operating said computer to calculate a first set of logical layers with specific thickness and outline for each layer and then periodically re-calculate another set of logical layers after periodically comparing the dimension data acquired by said sensor means with said computer aided design representation in an adaptive manner.

16. A method as defined in claim 1, further comprising the operations of burning off said binder after step (h) thereby forming a 3-D porous body and impregnating said porous 3-D body with a solidifying liquid material to form a solid 3-D object.

25. A method of claim 1, further comprising additional step of charging a layer of said primary body-building powder material with charges of opposite polarity to those charges created by said electro-photographic powder deposition means to facilitate transfer of a binder powder image to said layer of primary body-building powder material.

17. A solid freeform fabrication apparatus for making a three-dimensional object from multiple layers of solid powder and binder materials, said apparatus comprising:

(a) a work surface to support said object while being built;

(b) a powder-dispensing means at a predetermined initial distance from said work surface, said dispensing means having an outlet directed to said work surface for feeding successive layers of a body-building powder material onto said work surface one layer at a time;

(c) an electro-photographic powder deposition means disposed at a distance from said work surface for providing binder powder images onto said successive layers of a primary body-building powder material, one layer at a time;

(d) energy means in energy-supplying relation to said work surface and multiple layers of materials thereon for consolidating said multiple layers; and

(e) motion devices coupled to said work surface, said powder-dispensing means, and said electro-photographic powder deposition means for moving said powder-dispensing means and said electro-photographic powder deposition means relative to said work surface in a plane defined by first and second directions and in a third direction orthogonal to said plane to dispense and deposit said multiple layers of a primary body-building powder and binder materials, one layer at a time, for forming said 3-D object.

18. Apparatus as set forth in claim 17, wherein said powder-dispensing means comprises a powder-feeding drum.

19. Apparatus as set forth in claim 17, further comprising:

a computer-aided design computer and supporting software programs operative to create a three-dimensional geometry of said 3-D object, to convert said geometry into a plurality of data points defining the object, and to generate programmed signals corresponding to each of said data points in a predetermined sequence;

said computer being electronically linked to said electro-photographic powder deposition means for sending said programmed signals thereto to create said binder powder images; and

a motion controller electronically linked to said computer and said motion devices;

said motion controller being operative to actuate said motion devices in response to said programmed signals for said data points received from said computer.

20. Apparatus as set forth in claim 19, further comprising:

sensor means electronically linked to said computer and operative to periodically provide layer dimension data to said computer;

supporting software programs in said computer operative to perform adaptive layer slicing to periodically create a new set of layer data comprising data points defining the object in accordance with said layer dimension data acquired by said sensor means, and to generate programmed signals corresponding to each of said data points in a predetermined sequence.

21. Apparatus as set forth in claim 17, wherein said electro-photographic powder deposition means comprises devices selected from the group consisting of a corona discharging device, capacitor dot matrix charging device, thin photoconductive layer, scanning laser imaging device, charge cleaning device, and combinations thereof.

22. Apparatus as set forth in claim 17, wherein said powder-dispensing means and/or said work surface are provided with heating means for pre-heating the primary body-building powder material.

23. Apparatus as set forth in claim 17, wherein said energy means is selected from the group consisting of infrared, induction heating, dielectric heating, microwave heating, hot-air convective heating, and traditional conduction heating sources, ultra violet, X-ray, Gamma-ray, electron beam, laser beam, ion beam, plasma, and combinations thereof.

24. Apparatus as set forth in claim 17, wherein said work surface is provided with a protective environment.

26. A method for making a three-dimensional object from layers of primary body-building porous substrate and a binder powder, said method comprising the steps of:

positioning a work surface in proximity to, and at a predetermined initial distance from, means for storing and supplying said body-building porous substrate layers;

feeding a first layer of said body-building porous substrate onto said work surface;

electro-photographically depositing an image of a binder powder material onto selected areas of said first layer of body-building porous substrate;

applying energy means to said first layer for consolidating the body-building substrate material and the binder in said selected areas for building a cross-section of said object;

repeating said feeding, depositing, and applying steps to form a plurality of layers, each of said layers being integrally bonded to the next adjacent of said layers by said applying steps to form an integral 3-D body imbedded in a stack of binder-free portions of porous substrate serving as a support structure; and

removing said support structure, causing said 3-D object to appear.

27. A method according to claim 26, wherein said layers of porous substrate are pre-heated to a pre-selected temperature.

28. A method according to claim 26, further comprising additional step of charging a layer of said primary body-building porous substrate with charges of opposite polarity to those charges created by said electro-photographic powder deposition means to facilitate transfer of a binder powder image to said layer of primary body-building porous substrate.