Solid freeform fabrication of structurally engineered multifunctional devices

• US 7,509,240 B2
• Filed: 10/10/2002
• Issued: 03/24/2009
• Est. Priority Date: 10/15/2001
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Das, Suman, Santosa, James K, Hollister, Scott J, Krebsbach, Paul H
• Primary Examiner(s): Shah; Kamini S
• Assistant Examiner(s): Alhija; Saif A
• Application Number:
  US10/268,359
• Publication Number:
  US 20030074096A1
• Time in Patent Office: 2,357 Days
• Field of Search: 703/5
• US Class Current: 703/1
• CPC Class Codes: B29C 64/153 using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• CPC Class Codes: B29C 64/188 involving additional operations performed on the added layers, e.g. smoothing, grinding or thickness control surface shaping B29C59/00; after-treatment of articles without altering their shape B29C71/00
• 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 80/00 Products made by additive manufacturing

Abstract

A selective laser sintering technique and system are provided for producing a heterogeneous product. The selective laser sintering technique and system is generally comprised of generating a computer model of the product and processing the model to obtain numerous cross-sectional representations of the model. The cross-sectional representations are manufactured layer by layer to create the product. Specifically, numerous different powders having a variety of properties are placed within nozzles positioned above a deposition bed using a hopper. Using the computer model as a guide, the different powders are placed at different positions on the deposition bed to form each layer of the device. The deposited powders are consolidated, micromachined, and milled using one or more lasers to create the product. Using this selective laser sintering technique a wide variety of heterogenous products may be produced, such as the following: 1) bio-implants, 2) small scale energy production, storage and conversion devices, 3) devices that exploit anomalous material behavior, and 4) nanocomposites.

Claims

1. A selective laser sintering method for producing a heterogeneous product in which a model of said heterogeneous product is generated using a computer and said model is processed using an electronic processing device to obtain a plurality of cross-sectional layer representations of said model, said method comprising:

positioning an array of tapered delivery nozzles adjacent to a material deposition bed wherein said tapered delivery nozzles have a half angle less than 10.2 degrees;

filling said array of tapered delivery nozzles with different materials, said materials differing in at least one of composition and deposition properties using at least one hopper, said filling step comprised of disposing said different materials within a funnel of said hopper such that said materials pass though an aperture, said materials further passing through an elongated portion of a standpipe connected to said aperture and coming to rest within another portion of said standpipe; and

injecting a fluid through an aeration part located proximate said another portion to selectively cause said materials to exit said hopper through a terminal portion;

directing said nozzle array to various positions relative to said deposition bed;

disposing said materials simultaneously upon said deposition bed at said various positions;

consolidating said deposited materials with a laser source to form a consolidated cross-sectional layer; and

micromachining said consolidated cross-sectional layer with a pulsed laser source to form each of said plurality of cross-sectional layer representations of said model.

2. The method of claim 1, further comprising determining said various positions by processing said plurality of said cross-sectional layer representations using a control computer.

3. The method of claim 1, further comprising laser ablation of said cross-sectional layer representations to further define said features of said heterogeneous product.

4. The method of claim 1, further comprising introducing vibrational forces to at least one of said nozzles and said hopper.

5. The method of claim 1, further comprising providing said array as a sectional array having a size sufficient to cover a pre-selected partial portion of said deposition bed.

6. The method of claim 1, further comprising providing said array as a bed length array having a size sufficient to extend across an entire length of said deposition bed.

7. The method of claim 1, further comprising positioning said nozzles in a staggered configuration within said array.

8. The method of claim 1, further comprising the step of seeding said heterogeneous product with at least one of a drug, a protein, a gene, a virus, and any combination thereof.

9. The method of claim 1, wherein said materials are at least one of powders, liquids, particulate suspensions, and pastes.

10. The method of claim 1, further comprising varying a shape of a deposition opening of said nozzles to deposit a material line of a desired shape.

11. The method of claim 1, further comprising using said selective laser sintering method to produce a heterogeneous biomedical composite implant.

12. The method of claim 1, further comprising using said selective laser sintering method to produce at least one of a polymer-polymer composite, a polymer-biofactor composite, a polymer-ceramic composite, a polymer-biofactor-ceramic composite, a polymer-metal biomedical composite, a polymer-metal-ceramic composite, and a polymer-metal-biofactor- ceramic composite.

13. The method of claim 1, further comprising using said selective laser sintering method to produce one of either an energy production device, a storage device, a conversion device, or a nano- composite device.

14. The method of claim 1, wherein said nozzles further comprise micropipettes.

15. A selective laser sintering method for producing a heterogeneous product in which a model of said heterogenous product is generated using a computer and said model is processed using an electronic processing device to obtain a plurality of cross-sectional layer representations of said model, said method comprising:

positioning an array of tapered delivery nozzles adjacent to a material deposition bed, wherein said tapered delivery nozzles have a half angle less than 10.2 degrees;

filling said nozzle array with different materials, said materials differing in at least one composition and deposition properties; and

wherein said filling said tapered delivery nozzles with said materials using at least one hopper, said filling step comprised of disposing said materials within a funnel of said hopper such that said materials pass through an aperture within said funnel, said materials further passing through an elongated portion of a standpipe connected to said aperture and coming to rest within an angled portion of said standpipe; and

injecting a fluid through an aeration part located proximate said angled portion to selectively cause said materials to exit said hopper though a terminal portion at a controlled rate;

directing said tapered delivery nozzles to various positions relative to said deposition bed and disposing said materials simultaneously upon said deposition bed at said various positions to form each of said plurality of cross-sectional layer representations of said model;

consolidating said materials disposed upon said deposition bed; and

micromachining at least one of said consolidated cross-sectional layer representations with a pulsed laser source to form said heterogeneous product, wherein said consolidation and micromachining steps are performed using a closed-loop laser spot temperature control system that modulates laser power based on feedback from an in-situ emissivity measuring pyrometer.

16. The method of claim 15, further comprising laser ablation of said materials disposed upon said deposition bed to further define said features of said heterogeneous product.

17. The method of claim 16, wherein said laser ablation step is performed using a closed loop laser spot temperature control system that modulates laser power based on feedback from an in-situ emissivity measuring pyrometer.

18. The method of claim 15, further comprising determining said various positions by processing said plurality of said cross-sectional layer representations using a control computer.

19. The method of claim 15, further comprising introducing vibrational forces to at least one of said nozzles and said hopper.

20. The method of claim 15, wherein said materials are at least one of powders, liquids, pastes, and particulate suspensions.

21. The method of claim 15, wherein said nozzles further comprise micropipettes.

22. A selective laser sintering apparatus for producing a heterogenous product using a computer to generate a model of said heterogenous product and an electronic processing device to obtain a plurality of cross-sectional layer representations of said model, said system apparatus comprising:

an array of tapered delivery nozzles;

a deposition bed located adjacent said tapered delivery nozzles; and

a control device adapted to direct said array of tapered delivery nozzles to different positions relative to said deposition bed and controlling a deposit of materials simultaneously from said tapered delivery nozzles to said different positions upon said deposition bed;

wherein said tapered delivery nozzles have a half angle less than 10.2 degrees;

a hopper for filling said tapered delivery nozzles with said materials, said hopper comprised of;

a funnel;

a disk bonded within said funnel, said disk having numerous pores, said pores sized to permit passage of gas while restricting passage of said materials and an aperture; and

at least one aeration part positioned below said disk and a closed-loop laser spot temperature control system that modulates laser power based on feedback from an in-situ emissivity measuring pyrometer operable to consolidate and micromachine said deposit of materials.

23. The apparatus of claim 22, wherein said different positions are determined by said control device upon processing said plurality of cross-sectional layer representations.

24. The apparatus of claim 22, further comprising:

a laser adapted to consolidate said deposited materials to form said plurality of cross-sectional layer representations.

25. The apparatus of claim 22, wherein vibrational forces are introduced to at least one of said nozzles and said hopper.

26. The apparatus of claim 22, further comprising:

a standpipe extending from said funnel at a point below said disk, said standpipe comprised of;

a first portion;

a second portion extending from said first portion at an angle;

a third portion extending from said second portion at an angle; and

a second aeration part formed in at least one of said first, second, and third portions.

27. The apparatus of claim 22, wherein said array is a sectional array having a size sufficient to cover a pre-selected partial portion of said disposition bed.

28. The apparatus of claim 22, wherein said array is a bed length array that spans an entire length of said deposition bed.

29. The apparatus of claim 22, wherein said nozzles are positioned in a staggered configuration within said array.

30. The apparatus of claim 22, wherein said delivery nozzles are micropipettes.

31. The apparatus of claim 22, wherein said laser is modulated using a closed-loop laser spot temperature control system that modulates laser power based on feedback from an in-situ emissivity measuring pyrometer.

32. The apparatus of claim 22, wherein said nozzles comprise a filling point and a deposition opening.

33. The apparatus of claim 32, wherein a shape of said deposition opening is varied to deposit a material line of a desired shape.

34. The apparatus of claim 22, wherein said materials are at least one of powders, liquids, pastes, and particulate suspensions.

35. A device for filling tapered nozzles of a selective laser sintering system with materials, said device comprising:

a hopper for filling said tapered nozzles with said materials, said hopper comprised of;

a funnel having an aperture;

a disk bonded within said funnel, said disk having numerous pores, said cores sized to permit passage of gas while restricting passage of said materials;

a standpipe extending from said funnel and communicating with said aperture;

a stop valve disposed along said standpipe; and

an aeration portion disposed proximate said stop valve, said funnel is arranged to fill an array of tapered nozzles, said tapered nozzles having a half angle less than 10.2 degrees and vibrational forces are applied to at least one of said standpipe and to said nozzle to assist in movement of said materials though said device.

36. The device of claim 35, wherein said stop valve further comprises a portion of said standpipe angled relative to another portion of said standpipe extending from said funnel.

37. The device of claim 36, wherein said portion of said standpipe is angled at about 90 degrees relative to said another position.

38. The device of claim 36, wherein said portion further comprise an elbow of said standpipe.

39. The device of claim 38, further comprising a terminal portion of said standpipe extending at an angle relative to said elbow portion.

40. The device of claim 39, wherein said angle further comprises about a 90 degree angle.

41. The device of claim 35, wherein said funnel further comprises a sidewall and a disk connected to said sidewall, said disk including a plurality of pores therein.

42. The device of claim 41, wherein said pores are sized to permit gas to pass therethrough while preventing said materials from passing therethrough.

43. The device of claim 42, further comprising a second aeration part in communication with said pores.

44. The device of claim 35, wherein said materials are at least one of powders, liquids, pastes, and particulate suspensions.

45. The device of claim 35, wherein said nozzles further comprise micropipettes.

46. A device for filling tapered nozzles of a selective laser sintering system with materials, said device comprising:

a plurality of hoppers for filling said tapered nozzles with said materials, each of said plurality of hoppers comprised of;

a funnel having an aperture;

a disk bonded within said funnel, said disk having numerous pores, said pores sized to permit passage of gas while restricting passage of said materials a standpipe extending from said funnel and communicating with said aperture;

a stop valve disposed along said standpipe; and

an aeration portion disposed proximate said stop valve, wherein each said funnel fills a respective one of said tapered nozzles, said tapered nozzles having a half angle less than 10.2 degrees and wherein vibrational forces are applied to at least one of said standpipe and to said tapered nozzles to assist in movement of said materials though said device.