06148936 is referenced by 72 patents and cites 11 patents.

A rotary drill bit is manufactured by a powder metallurgy process by placing a metal mandrel in a mold, packing the mold with particulate matrix-forming material, infiltrating the material with a molten binding alloy, and cooling the assembly to form a solid infiltrated matrix bonded to the mandrel. The mandrel comprises an outer part surrounded by the matrix-forming material and an inner part, secured to the outer part but out of contact with the matrix-forming material. The outer part of the mandrel is formed from a material having thermal characteristics close to those of the matrix, so as to reduce the tendency for the matrix to crack under thermal stress, while the inner part of the mandrel is formed from a precipitation-hardening material, the strength and hardness of which increases in the infiltration process and the subsequent heating/cooling cycle for brazing the cutters on to the drill bit. The threaded shank of the drill bit is formed directly on the inner part since it will have sufficient strength and hardness for this purpose.

Title
Methods of manufacturing rotary drill bits
Application Number
9/244471
Publication Number
6148936
Application Date
February 4, 1999
Publication Date
November 21, 2000
Inventor
Andrew Bell
Eastington
GB
Stephen Martin Evans
Standish
GB
Agent
Jeffery E Daly
Assignee
Camco International
GB
IPC
E21B 10/62
E21B 10/08
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