Directional solidification of polycrystalline diamond compact (PDC) drill bits

Patent metadata

Field	Value
Publication number	US-9993869-B2
Application number	US-201314759510-A
Country	US
Kind code	B2
Filing date	Mar 15, 2013
Priority date	Mar 15, 2013
Publication date	Jun 12, 2018
Grant date	Jun 12, 2018

Abstract

A method of manufacturing a rotary drill bit includes forming a mold having an inner surface and an outer surface, locating a metal mandrel within the mold, packing the mold around at least part of the mandrel with particulate matrix-forming material and installing an insulating material around at least an upper portion of the outer surface. The material is infiltrated in a furnace with a molten binding alloy and the mold including the insulating material is removed from the furnace, directionally solidifying the material and binding alloy in portion of the bit, wherein the directional solidification proceeds from the lower portion of the outer surface in an upward and outward direction to form a solid infiltrated matrix bonded to the mandrel by cooling of the mold with the insulating material disposed around at least the upper portion of the outer surface of the mold.

First claim

What is claimed is:

1. A method of manufacturing a rotary drill bit comprising a bit body having a shank for connection to a drill string and a leading face on which cutters are mounted, the method comprising:
forming a mold assembly, said mold assembly comprising at least a mold for said bit, a connector ring, and a funnel, said mold assembly having an inner surface and an outer surface;
locating a metal mandrel within the mold assembly, packing the mold assembly around at least part of the metal mandrel with particulate matrix-forming material, the metal mandrel positioned between said connector ring and said funnel;
installing an insulating material around at least exterior sides of the outer surface, said insulating material laterally adjacent at least the metal mandrel and the connector ring, but not extending substantially below the connector ring;
infiltrating said matrix forming material in a furnace with a molten binding alloy;
removing the mold assembly including the insulating material on the outer surface from the furnace;
directionally solidifying the matrix forming material and binding alloy in a portion of said bit, wherein said directional solidification proceeds from the lower portion of the outer surface in an upward and outward direction to form a solid infiltrated matrix bonded to the metal mandrel by cooling of the mold assembly with the insulating material disposed at least adjacent the metal mandrel and the connector ring.

2. The method of claim 1 further including removing the insulating material after the internal temperature of the solidifying material in the portion of the bit has cooled to below 1700 degrees F.

3. The method of claim 1 further including forming the mold of graphite.

4. The method claim 3 wherein forming the mold further includes imprinting a layer of sand covering at least an upper portion of the inner surface of the mold wherein said sand further insulates the solidifying material during the cooling of the mold.

5. The method claim 3 wherein forming the mold further includes inserting a secondary mold into the first/primary mold with a layer of sand covering at least the upper portion of the inner surface of the mold wherein said sand further insulates the solidifying material during the cooling of the mold.

6. The method of claim 1 further including forming the mold of sand.

7. The method of claim 1 further including forming the mold of ceramics.

8. The method of claim 1 further including forming the mold of boron nitride.

9. The method of claim 1 wherein the insulating material includes a reflective surface disposed toward at least the upper portion of the outer surface of the mold.

10. The method of claim 1 wherein the insulating material is pre-formed in a plurality of insulation pieces and said method of installing includes assembling said pre-formed insulation pieces to form a substantially cylindrical shape wherein an inner surface of the cylindrical shape conforms to the at least upper portion of the outer surface of the mold.

11. A method of reducing discontinuities in the matrix of a rotary bit body, said bit body having a shank for connection to a drill string and a leading face on which cutters are mounted, the method comprising:
forming a mold assembly, said mold assembly comprising at least a mold for said bit body, a connector ring, and a funnel, said mold assembly, said mold assembly having an inner surface and an outer surface;
locating a metal mandrel within the mold, packing the mold assembly around at least part of the metal mandrel with particulate matrix-forming material, the metal mandrel positioned between said connector ring and said funnel;
installing an insulating material around at least exterior sides of the outer surface, said insulating material laterally adjacent at least the metal mandrel and the connector ring, but not extending substantially below the connector ring;
infiltrating said matrix forming material in a furnace with a molten binding alloy;
removing the mold assembly including the insulating material on the outer surface from the furnace;
cooling of the mold assembly with the insulating material disposed at least adjacent the metal mandrel and the connector ring to form a solid infiltrated matrix bonded to the mandrel;
wherein at least a portion of the solid infiltrated matrix of the bit body proximal to an area of the outer surface of the mold assembly where the insulating material is disposed, has fewer discontinuities than the same area of a bit manufactured by a substantially similar process without insulating material disposed at least adjacent the metal mandrel and the connector ring.

Assignees

• Halliburton Energy Services Inc

Inventors

• Atkins William Brian
• Thomas Jeffrey

Classifications

• B22D19/06

  for manufacturing or repairing tools · CPC title

• B22D27/045 Primary

  Directionally solidified castings · CPC title

• E21B10/42

  Rotary drag type drill bits with teeth, blades or like cutting elements, e.g. fork-type bits, fish tail bits (characterised by wear resisting parts E21B10/46; by conduits or nozzles for drilling fluid E21B10/60; by detachable or adjustable parts E21B10/62) · CPC title

• B22F2007/066

  using impregnation · CPC title

• C22C29/08

  based on tungsten carbide · CPC title