Controlled laser production of elongated articles from particulates

• US 6,429,402 B1
• Filed: 06/02/2000
• Issued: 08/06/2002
• Est. Priority Date: 01/24/1997
• Status: Expired due to Fees

• Current Assignee: Los Alamos National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Milewski, John O., Dixon, Raymond D., Lewis, Gary K.
• Primary Examiner(s): Heinrich, Samuel M.
• Application Number:
  US09/587,183
• Time in Patent Office: 795 Days
• Field of Search: 219/121.6, 219/121.63, 219/121.64, 219/121.65, 219/121.66, 219/121.78, 219/121.82, 219/121.85
• US Class Current: 219/121.63
• 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 10/32 of the atmosphere, e.g. composition or pressure in a building chamber
• CPC Class Codes: B22F 10/36 of energy beam parameters
• CPC Class Codes: B22F 10/73 of powder
• CPC Class Codes: B22F 5/12 of wires of tubes B22F5/10
• CPC Class Codes: B23K 26/34 Laser welding for purposes other than joining
• CPC Class Codes: B29C 2791/005 Using a particular environment, e.g. sterile fluids other than air
• CPC Class Codes: B29C 64/153 using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

It has been discovered that wires and small diameter rods can be produced using laser deposition technology in a novel way. An elongated article such as a wire or rod is constructed by melting and depositing particulate material into a deposition zone which has been designed to yield the desired article shape and dimensions. The article is withdrawn from the deposition zone as it is formed, thus enabling formation of the article in a continuous process. Alternatively, the deposition zone is moved along any of numerous deposition paths away from the article being formed.

Claims

1. A method of forming a wire from materials in particulate form, said method comprising:

(a) defining the shape and dimensions of a wire;

(b) creating control commands effective to form said wire by deposition of molten material along a deposition path in a single axis;

(c) focusing a laser beam at a location within a deposition zone;

(d) providing particulate material to said deposition zone;

(e) forming a pool of molten material in said deposition zone by melting a portion of an article support and said particulate material by means of energy provided by said laser beam;

(f) depositing molten material from said deposition zone on said article support at points along a first portion of said deposition path by moving said deposition zone along said deposition path, where said molten material solidifies after leaving said deposition zone, in order to form a portion of said wire which is adjacent to said article support;

(g) forming a pool of molten material in said deposition zone by melting a portion of said partially formed wire and said particulate material by means of energy provided by said laser beam;

(h) depositing molten material from said deposition zone at points along a second portion of said deposition path by moving said deposition zone along said deposition path, where said molten material solidifies after leaving said deposition zone, in order to continue formation of said wire; and

(i) controlling flow of particulate material into said deposition zone, energy density of said laser beam, speed of withdrawal of said deposition zone from wire being formed, and focal position of said laser beam by means of said control commands as deposition takes place.

3. A method as recited in claim 1 wherein said method is carried out in a controlled atmosphere.

5. A method as recited in claim 1 wherein said deposition zone is exposed to a magnetic field.

7. A method as recited in claim 1 wherein any particulate material escaping unused from said deposition zone is recycled back to a particulate material supply for supplying said deposition zone.

9. A method as recited in claim 1 wherein shape and dimensions of a wire are defined by use of and within a digital computer.

11. A method as recited in claim 1 wherein said control commands are executed by apparatus under control of a digital computer containing a program specifying locations on the deposition path at which the control commands are to be executed.

13. A method as recited in claim 1 wherein said flow of particulate material into said deposition zone, energy density of said laser beam, and speed of movement of said deposition zone along said deposition path are controlled by a computer program for forming a wire created in a digital computer by:

(a) creating a design file containing shape and dimensions of said article;

(b) creating a tool path effective to form the article defined by said design file; and

(c) establishing control commands effective to form said wire and embedding the control commands in the tool path.

15. A method as recited in claim 13 wherein said design file is created by use of a computer-aided design program.

17. A method as recited in claim 13 wherein said tool path with embedded control commands is created by use of an adapted computer-aided manufacturing program.

19. A method as recited in claim 1 further characterized in that:

(a) shape and dimensions of said wire are defined in a digital design file created by use of a computer-aided design program;

(b) a digital cutter location file is created using said design file and an adapted computer-aided manufacturing program;

(c) a digital post-processor specific to laser deposition apparatus is created;

(d) a digital machine operating file is created by operating upon said cutter location file with said post-processor; and

(e) apparatus for moving the deposition zone along a deposition path and executing the control commands is controlled by a digital computer directed by said machine file.

21. A method as recited in claim 1 wherein computer numerical control apparatus is used to move said deposition zone along said deposition path.

23. A method as recited in claim 1 wherein powder composition is varied during formation of a wire.

25. A method as recited in claim 1 wherein at least two powder paths are utilized.

27. A method as recited in claim 25 wherein said powder paths are arranged in pairs, and a first path of a pair is oriented about 180 degrees from a second path of the pair.

29. A method as recited in claim 1 wherein a wire of variable density is formed.

31. A method as recited in claim 1 wherein said control commands comprise commands to:

(a) ramp up laser power;

(b) turn on flow of particulate material;

(c) turn on gas flow;

(d) move deposition head to location where deposition is to begin;

(e) open laser shutter;

(f) dwell in said location for a time sufficient to create a molten pool and begin deposition;

(g) move laser head relative to molten pool while continuing deposition;

(h) close laser shutter;

(i) move deposition head away from wire formed;

(j) turn flow of particulate material off;

(k) turn gas flow off; and

(l) ramp down laser power.

2. A method of forming a wire from materials in particulate form, said method comprising:

(a) defining the shape and dimensions of a wire;

(b) creating control commands effective to form said wire by deposition of molten material along a deposition path in a single axis;

(c) focusing a laser beam at a location within said deposition zone;

(d) providing particulate material to said deposition zone;

(e) forming a pool of molten material in said deposition zone by melting a portion of an article support and said particulate material by means of energy provided by said laser beam;

(f) depositing molten material from said deposition zone on said article support at points along a first portion of said deposition path by moving said article support away from said deposition zone as said molten material solidifies after leaving said deposition zone, in order to form a portion of said wire which is adjacent to said article support;

(g) forming a pool of molten material in said deposition zone by melting a portion of said partially formed wire and said particulate material by means of energy provided by said laser beam;

(h) depositing molten material from said deposition zone at points along a second portion of said deposition path by moving said partially formed wire away from said deposition zone in accordance with said deposition path as said molten material solidifies after leaving said deposition zone, in order to continue formation of said wire; and

(i) controlling flow of particulate material into said deposition zone, and energy density of said laser beam, focal position of said laser beam, and speed of withdrawal of said wire being formed from said deposition zone by means of said control commands as deposition takes place.

4. A method as recited in claim 2 wherein said method is carried out in a controlled atmosphere.

6. A method as recited in claim 2 wherein said deposition zone is exposed to a magnetic field.

8. A method as recited in claim 2 wherein any particulate material escaping unused from said deposition zone is recycled back to a particulate material supply for supplying said deposition zone.

10. A method as recited in claim 2 wherein shape and dimensions of a wire are defined by use of and within a digital computer.

12. A method as recited in claim 2 wherein said control commands are executed by apparatus under control of a digital computer containing a program specifying locations on the deposition path at which the control commands are to be executed.

14. A method as recited in claim 2 wherein said flow of particulate material into said deposition zone, energy density of said laser beam, and speed of movement of said deposition zone along said deposition path are controlled by a computer program for forming a wire created in a digital computer by:

(a) creating a design file containing shape and dimensions of said article;

(b) creating a tool path effective to form the article defined by said design file; and

(c) establishing control commands effective to form said wire and embedding the control commands in the tool path.

16. A method as recited in claim 14 wherein said design file is created by use of a computer-aided design program.

18. A method as recited in claim 14 wherein said tool path with embedded control commands is created by use of an adapted computer-aided manufacturing program.

20. A method as recited in claim 2 further characterized in that:

(a) shape and dimensions of said wire are defined in a digital design file created by use of a computer-aided design program;

(b) a digital cutter location file is created using said design file and an adapted computer-aided manufacturing program;

(c) a digital post-processor specific to laser deposition apparatus is created;

(d) a digital machine operating file is created by operating upon said cutter location file with said post-processor; and

(e) apparatus for moving the deposition zone along a deposition path and executing the control commands is controlled by a digital computer directed by said machine file.

22. A method as recited in claim 2 wherein computer numerical control apparatus is used to move said wire away from said deposition zone.

24. A method as recited in claim 2 wherein powder composition is varied during formation of a wire.

26. A method as recited in claim 2 wherein at least two powder paths are utilized.

28. A method as recited in claim 26 wherein said powder paths are arranged in pairs, and a first path of a pair is oriented about 180 degrees from a second path of the pair.

30. A method as recited in claim 2 wherein a wire of variable density is formed.

32. A method as recited in claim 2 wherein said control commands comprise commands to:

(a) ramp up laser power;

(b) turn on flow of particulate material;

(c) turn on gas flow;

(d) move deposition head to location where deposition is to begin;

(e) open laser shutter;

(f) dwell in said location for a time sufficient to create a molten pool and begin deposition;

(g) move wire being formed relative to molten pool while continuing deposition;

(h) close laser shutter;

(i) move wire formed away from deposition head;

(j) turn flow of particulate material off;

(k) turn gas flow off; and

(l) ramp down laser power.

33. An apparatus for forming a wire from materials in particulate form, said apparatus comprising:

(a) a means for defining the shape and dimensions of a wire, said means being capable of creating control commands effective to form a wire by depositions of molten material along a deposition path in a single axis;

(b) a feed mechanism for introducing particulate material into a deposition zone;

(c) a laser positioned to focus a laser beam into said particulate material in said deposition zone;

(d) a supporting and drawing device for moving said wire away from said deposition zone; and

(e) a controller for controlling flow of said particulate material, energy density of said laser beam, focal position of said laser beam, and speed of withdrawal of wire being formed from said deposition zone by using said control commands.

34. An apparatus for forming an wire from materials in particulate form, said apparatus comprising:

(a) a means for defining the shape and dimensions of a wire, said means being capable of creating control commands effective to form a wire by depositions of molten material along a deposition path in a single axis;

(b) a feed mechanism for introducing particulate material into a deposition zone;

(c) a laser positioned to focus a laser beam into said particulate material in said deposition zone;

(d) a supporting device for holding said wire in said deposition zone;

(e) a means for moving said deposition zone along said deposition path away from said wire;

(f) a controller for controlling flow of said particulate material, energy density of said laser beam, focal position of said laser beam, and speed of withdrawal of said deposition zone from wire being formed by using said control commands.