METHODS OF FORMING BODIES FOR EARTH-BORING DRILLING TOOLS COMPRISING MOLDING AND SINTERING TECHNIQUES, AND BODIES FOR EARTH-BORING TOOLS FORMED USING SUCH METHODS

• US 20100154587A1
• Filed: 12/22/2008
• Published: 06/24/2010
• Est. Priority Date: 12/22/2008
• Status: Active Grant

• Current Assignee: Baker Hughes Holdings LLC (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Eason, Jimmy W.
• Granted Patent: US 9,139,893 B2
• Time in Patent Office: Days
• US Class Current: 75/230
• CPC Class Codes: B22F 1/102 Metallic powder coated with organic material
• CPC Class Codes: B22F 2003/247 Removing material: carving, cleaning, grinding, hobbing, honing, lapping, polishing, milling, shaving, skiving, turning the surface
• CPC Class Codes: B22F 2005/001 Cutting tools, earth boring or grinding tool other than table ware
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 3/004 Filling molds with powder feeding material to presses in general B30B15/302
• CPC Class Codes: B22F 3/10 Sintering only
• CPC Class Codes: B22F 3/225 by injection molding
• CPC Class Codes: B22F 3/24 After-treatment of workpieces or articles B22F3/1146 takes precedence
• CPC Class Codes: B22F 5/00 Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
• CPC Class Codes: C22C 1/051 Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor
• CPC Class Codes: C22C 29/02 based on carbides or carbonitrides

Abstract

Methods of fabricating bodies of earth-boring tools include mechanically injecting a powder mixture into a mold cavity, pressurizing the powder mixture within the mold cavity to form a green body, and sintering the green body to a desired final density to form at least a portion of a body of an earth-boring tool. For example, a green bit body may be injection molded, and the green bit body may be sintered to form at least a portion of a bit body of an earth-boring rotary drill bit. Intermediate structures formed during fabrication of an earth-boring tool include green bodies having a plurality of hard particles, a plurality of matrix particles comprising a metal matrix material, and an organic material that includes a long chain fatty acid derivative. Structures formed using the methods of fabrication are also disclosed.

Claims

1. A method of fabricating a body of an earth-boring tool, comprising:

forming a powder mixture by mixing hard particles, matrix particles comprising a metal matrix material, and an organic material;

mechanically injecting the powder mixture into a mold cavity having a shape corresponding to at least a portion of a body of an earth-boring tool;

applying pressure to the powder mixture within the mold cavity to form a green body; and

sintering the green body to form at least a portion of a body of an earth-boring tool.

2. The method of claim 1, wherein forming a powder mixture further comprises selecting the organic material to comprise a long chain fatty acid derivative.

3. The method of claim 1, further comprising:

forming the mold cavity in a water soluble mold; and

dissolving the mold in a polar solvent after forming the green body to remove the green body from the mold cavity.

4. The method of claim 3, further comprising forming the water soluble mold to comprise at least one of polyvinyl alcohol (PVA) and polyethylene glycol.

5. The method of claim 1, further comprising selecting the hard particles to comprise a material selected from the group consisting of diamond, boron carbide, boron nitride, aluminum nitride, silicon nitride, and carbides or borides of W, Ti, Mo, Nb, V, Hf, Zr, Si, Ta, and Cr.

6. The method of claim 5, further comprising selecting the matrix particles to comprise a metal selected from the group consisting of iron, nickel, cobalt, titanium, aluminum, copper-based alloys, iron-based alloys, nickel-based alloys, cobalt-based alloys, titanium-based alloys, and aluminum-based alloys.

7. The method of claim 1, further comprising coating the hard particles and the matrix particles with the organic material prior to injecting the powder mixture into the mold cavity.

8. The method of claim 1, wherein applying pressure to the powder mixture comprises applying a pressure of between about 10 pounds per square inch (about 0.07 megapascals) and about 100 pounds per square inch (about 0.7 megapascals).

9. The method of claim 8, wherein applying pressure to the powder mixture comprises packing the powder mixture within the mold cavity to a packing density of about 80% by volume or more.

10. The method of claim 1, further comprising at least substantially isostatically compressing the green body prior to sintering the green body to form at least a portion of body of an earth-boring tool

11. The method of claim 1, wherein the hard particles and the matrix particles comprise a first group of particles having a first average particle size, a second group of particles having a second average particle size about seven times greater than the first average particle size, and a third group of particles having an average particle size about thirty five times greater than the first average particle size.

12. The method of claim 1, wherein injecting the powder mixture into a mold cavity comprises injecting the powder mixture into a mold cavity having a shape corresponding to at least a portion of a bit body for an earth-boring rotary drill bit.

13. The method of claim 1, further comprising selecting the organic material of the powder mixture to comprise less than about 5% by weight of the powder mixture.

14. The method of claim 1, further comprising forming the hard particles and the matrix particles to be at least substantially spherical.

15. The method of claim 1, wherein mechanically injecting the powder mixture into the mold cavity comprises forcing the powder mixture through a barrel using a rotating screw within the barrel.

16. The method of claim 1, wherein mechanically injecting the powder mixture into the mold cavity comprises forcing the powder mixture through a pot by longitudinally displacing a piston within the pot.

17. A method of fabricating a bit body of an earth-boring rotary drill bit, comprising:

injection molding a green bit body comprising a plurality of hard particles, a plurality of matrix particles comprising a metal matrix material, and an organic material; and

sintering the green bit body to form an at least substantially fully dense bit body of an earth-boring rotary drill bit.

18. The method of claim 17, further comprising:

partially sintering the green bit body to form a brown bit body;

machining the brown bit body; and

sintering the brown bit body to a desired final density.

19. The method of claim 17, wherein machining the brown bit body comprises:

machining at least a portion of a cutting element pocket in a surface of the brown bit body; and

securing at least one cutting element within the cutting element pocket.

20. The method of claim 17, further comprising selecting the organic material to comprise a long chain fatty acid derivative.

21. The method of claim 17, wherein injection molding the green bit body comprises injection molding the green bit body in a water soluble mold.

22. The method of claim 21, further comprising dissolving the mold in a polar solvent after forming the green body to remove the green body from the mold cavity.

23. The method of claim 21, further comprising forming the water soluble mold to comprise at least one of polyvinyl alcohol (PVA) and polyethylene glycol.

24. An intermediate structure formed during fabrication of a body of an earth-boring tool, comprising:

a green body having a shape corresponding to a body of an earth-boring tool and comprising;

a plurality of hard particles;

a plurality of matrix particles comprising a metal matrix material; and

an organic material comprising a long chain fatty acid derivative.