Method and system for producing complex-shape objects

• US 6,046,426 A
• Filed: 07/08/1996
• Issued: 04/04/2000
• Est. Priority Date: 07/08/1996
• Status: Expired due to Term

• Current Assignee: Sandia Corporation (Martin Marietta Corporation)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Keicher, David M., Schanwald, Lee P., Jeantette, Francisco P., Romero, Joseph A.
• Primary Examiner(s): Evans, Geoffrey S.
• Application Number:
  US08/676,547
• Time in Patent Office: 1,366 Days
• Field of Search: 219/121.63, 219/121.64, 219/121.65, 219/121.66, 219/121.83, 219/121.6, 219/121.62, 219/121.84, 264/400, 264/402, 264/409, 264/497, 427/554, 427/556, 427/555, 427/596, 427/597
• US Class Current: 219/121.63
• CPC Class Codes: B01F 23/32 by introducing solids in gas volumes
• CPC Class Codes: B01F 33/406 in receptacles with gas supply only at the bottom B01F33/405 takes precedence
• CPC Class Codes: B01F 35/7141 using measuring chambers moving between a loading and unloading position, e.g. reciprocating feed frames
• CPC Class Codes: B22F 10/25 Direct deposition of metal particles, e.g. direct metal deposition [DMD] or laser engineered net shaping [LENS]
• CPC Class Codes: B22F 10/85 for controlling or regulating additive manufacturing processes
• CPC Class Codes: B22F 12/41 characterised by the type, e.g. laser or electron beam
• CPC Class Codes: B22F 12/52 Hoppers
• CPC Class Codes: B22F 12/53 Nozzles
• CPC Class Codes: B22F 12/55 Two or more means for feeding material
• CPC Class Codes: B22F 12/90 Means for process control, e.g. cameras or sensors
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: B23K 26/144 the fluid stream containing particles, e.g. powder
• CPC Class Codes: B23K 26/1464 Supply to, or discharge from, nozzles of media, e.g. gas, powder, wire
• CPC Class Codes: B23K 26/1482 Detachable nozzles, e.g. exchangeable or provided with breakaway lines
• CPC Class Codes: B29C 41/36 Feeding the material on to the mould, core or other substrate
• CPC Class Codes: B29C 41/52 Measuring, controlling or regulating
• CPC Class Codes: B29C 64/153 using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• 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: Y02P 10/25 Process efficiency

Abstract

A method and system are provided for producing complex, three-dimensional, net shape objects from a variety of powdered materials. The system includes unique components to ensure a uniform and continuous flow of powdered materials as well as to focus and locate the flow of powdered materials with respect to a laser beam which results in the melting of the powdered material. The system also includes a controller so that the flow of molten powdered materials can map out and form complex, three-dimensional, net-shape objects by layering the molten powdered material. Advantageously, such complex, three-dimensional net-shape objects can be produced having material densities varying from 90% of theoretical to fully dense, as well as a variety of controlled physical properties. Additionally, such complex, three-dimensional objects can be produced from two or more different materials so that the composition of the object can be transitioned from one material to another.

Claims

1. A system for producing three-dimensional, net-shape objects from powdered material, comprising:

a) a deposition stage;

b) a growth surface which moves in accord with the deposition stage;

c) a laser configured to direct a laser beam onto the growth surface;

d) a molten region on the growth surface, generated by the action of the laser beam thereon, comprising;

1) melted material from the growth surface; and

,

2) powdered material which melts on incorporation into the molten region;

e) a delivery system comprising;

1) a passageway therethrough whereby said laser beam can be transmitted substantially without attenuation;

2) a plurality of nozzles circumferentially positioned about said passageway and aligned so as to produce a converging flow of a propellant gas and powdered material mixture such that the apex of such converging flow is substantially directed at said molten region;

3) a manifold which distributes said propellant gas and powdered material mixture to said plurality of nozzles,

f) a powder feeder supplying the manifold of said delivery system with a substantially continuous and uniform flow of a propellant gas and powdered material mixture; and

,

g) means for translating the delivery system relative to the deposition stage and for depositing layers comprising melted and resolidified powdered material so as to form three-dimensional, net-shape objects.

2. The system of claim 1, wherein the three-dimensional net-shape objects have a density of at least 90% of the theoretical density of the powdered material.

3. The system of claim 1, further including a closed chamber adapted to house said delivery means and the deposition stage.

4. The system of claim 1, wherein the laser includes means for positioning the focal plane of the laser beam at a substantially fixed distance from the growth surface during deposition.

5. The system of claim 4, wherein said positioning means includes:

a) triangulation means for determining the distance to the growth surface from the focal plane of the laser beam; and

b) means for vertically translating the focal plane of the laser beam to maintain the fixed distance.

6. The method of claim 1, wherein the three-dimensional net-shape objects have a density substantially equal to the theoretical density of the powdered material.

7. The system of claim 1, further including means for removing unincorporated powdered material from the growth surface.

8. The system of claim 1, further comprising:

a) at least two powder feeders, each providing a substantially continuous and uniform flow of different propellant gas and powdered material mixtures to a combination mixer; and

,

b) the combination mixer having inputs for said different propellant gas and powdered material mixtures, an output for the combined flow leading to the delivery system, and a regulating system to control the amount of each said mixture combined to make up said combined flow.

9. The system of claim 8, wherein each powder feeder comprises:

a) a pressurized hopper adapted to store the powdered material;

b) a rotary feeder wheel rotatably mounted with the hopper, wherein the rotary feeder wheel has a plurality of flow passageways therethrough positioned in concentric rings about the feeder wheel and each flow passageway is sized to transport a measured amount of powdered material from the hopper;

c) a slotted propellant gas inlet positioned beneath the rotary feed wheel a adapted to direct a flow of propellant gas through the flow passageways when the slotted propellant gas inlet and the flow passageways cone into registry;

d) a propellant gas and powdered material mixture outlet positioned above the rotary feeder wheel and substantially in vertical alignment with the slotted propellant gas inlet;

e) a propellant gas in fluid communications with the slotted propellant gas inlet; and

f) means for rotating the rotary feeder wheel whereby when a flow passageway containing a measured amount of powdered material comes into registry with the slotted propellant gas inlet and the propellant gas and powdered material mixture outlet, a substantially continuous and uniform flow of a propellant gas and powdered material mixture is directed to said delivery system.

10. The system of claim 1, wherein said powder feeder comprises:

a. a hopper adapted for storing powdered material;

b. a rotary feeder wheel rotatably mounted with the hopper and having a plurality of flow passageways sized to transport a measured amount of powdered material spaced in concentric rings thereabout;

c. a slotted propellant gas inlet positioned beneath the rotary feeder wheel and adapted to direct a flow of propellant gas through the flow passageways when the slotted propellant gas inlet and the flow passageways come into registry;

d. a propellant gas and powdered material mixture outlet, positioned above said rotary feeder wheel and in vertical alignment with said slotted propellant gas inlet; and

e. means for rotating the rotary feeder wheel and for transporting the measured amount of powdered material from the hopper via the flow passageways such that when the flow passageways, slotted propellant gas inlet, and the propellant gas and powdered material mixture outlet are all in registry, a substantially uniform and continuous flow of propellant gas and powdered material mixture is directed to said delivery system.

11. The system of claim 1, further including flow sensing means for measuring the rate of flow of powdered material from said powder feeder.

12. The system of claim 1, further including means for determining the temperature of the molten region.

13. The system of claim 12, wherein said means for determining temperature comprises a pyrometer coaxially aligned with the laser beam.

14. The system of claim 12, further including means for regulating laser power based on the temperature of the molten region.

15. The system of claim 1, further including means for regulating the temperature of the molten region.

16. The system of claim 1, further including an automated controller to direct the translation of said delivery system relative to the deposition stage.

17. The system of claim 16, wherein said automated controller also regulates the temperature of the molten region.

18. The system of claim 16, wherein said automated controller also maintains the focal plane of the laser beam at a substantially fixed distance with respect to the growth surface.

19. The system of claim 16, wherein said automated controller also regulates the power level of the laser.

20. The system of claim 1, wherein the powdered material is selected from the group consisting of metals, ceramics, glasses and plastics.

21. The system of claim 1, wherein said propellant gas is selected from the group consisting of:

nitrogen-containing gases, carbon-containing gases, inert gases, oxidizing, and reducing gases.

22. The system of claim 1, wherein said translation means comprises:

a) means for translating the deposition stage in a horizontal plane; and

b) means for translating the focal plane of the laser beam in a vertical plane.

23. The system of claim 1, wherein said delivery system further comprises means for injecting a shield gas coaxial with the converging flow of powdered material.

24. A method for producing three-dimensional, net-shape objects from powdered material, comprising the steps of:

a) forming a molten region on a growth surface by directing a laser beam thereon;

b) generating a substantially continuous and uniform flow of a propellant gas and powdered material mixture;

c) converting said flow into a converging flow by spraying said flow through a plurality of nozzles circumferentially positioned about the laser beam;

d) incorporating a portion of the powdered material contained in said converging flow into the molten region by positioning the apex of the converging flow proximate to said molten region; and

,

e) translating the molten region so as to deposit layers comprising melted and resolidified powdered material so as to form a three-dimensional, net-shape object.

25. The method of claim 24, further including regulating the power level of the laser so as to regulate the temperature of the molten region.

26. The method of claim 25, further including obtaining a measure of the temperature of the molten region with an optical pyrometer.

27. The method of claim 24, wherein the powdered material is selected from the group consisting of metals, ceramics, glasses and plastics.

28. The method of claim 24, wherein the three-dimensional net-shape objects have a density of at least 90% of the theoretical density of the powdered material.

29. The method of claim 28, wherein the density is substantially equal to the theoretical density of the powdered material.

30. The method of claim 24 wherein the step of generating a substantially continuous and uniform flow of a propellant gas and powdered material mixture further comprises:

a) pressurizing a hopper adapted to store the powdered material;

b) transporting a measured amount of powdered material from the hopper with a rotary feeder wheel rotatably mounted with said hopper, wherein the rotary feeder wheel has a plurality of flow passageways therethrough positioned in concentric rings about the feeder wheel, each flow passageway being sized to transport a measured amount of powdered material from the hopper; and

,

c) rotating the rotary feeder wheel whereby when a flow passageway containing a measured amount of powdered material comes into registry with a source of propellant gas, a substantially continuous and uniform flow of a propellant gas and powdered material mixture is generated.

31. A system for producing three-dimensional objects from powdered material, comprising:

a) a deposition stage;

b) a growth surface which moves in accord with the deposition stage;

c) a laser configured to direct a laser beam onto the growth surface;

d) a molten region on the growth surface, generated by the action of the laser beam thereon, comprising;

1) melted material from the growth surface; and

,

2) powdered material which melts on incorporation into the molten region;

e) a delivery system, comprising;

1) a passageway therethrough whereby said laser beam can be transmitted substantially without attenuation;

2) a plurality of nozzles circumferentially positioned about said passageway and aligned so as to produce a converging flow of a propellant gas and powdered material mixture such that the apex of such converging flow is substantially directed at said molten region;

3) a manifold which distributes said propellant gas and powdered material mixture to said plurality of nozzles;

f) a powder feeder supplying the manifold of said delivery system with a substantially continuous and uniform flow of a propellant gas and powdered material mixture; and

,

g) means for translating the delivery system relative to the deposition stage and for depositing layers comprising melted and resolidified powdered material so as to form three-dimensional objects.

32. The system of claim 31, wherein the three-dimensional objects are bulk materials.

33. A method for producing three-dimensional objects from a plurality of powdered materials and their combinations, comprising the steps of:

a) forming a molten region on a growth surface by directing a laser beam thereon;

b) generating a plurality of substantially continuous and uniform mixture flows, each said mixture flow comprising a propellant gas and at least one of the plurality of powdered materials;

c) combining the plurality of substantially continuous and uniform mixture flows into a predetermined master flow, the composition of which is determined by regulating the amount of each of the plurality of substantially continuous and uniform mixture flows that is combined into said master flow;

d) converting said master flow into a converging flow by spraying said master flow through a plurality of nozzles circumferentially positioned about the laser beam;

e) incorporating a portion of the mixed powdered materials contained in said converging flow into the molten region by positioning the apex of the converging flow proximate to said molten region; and

f) translating the molten region so as to deposit layers comprising melted and resolidified powdered materials so as to form a three-dimensional object.