ROCK BIT CUTTER CONES HAVING METALLURGICALLY BONDED CUTTER INSERTS

摘要

A rock bit cutter cone (10) for a drill bit (12) is disclosed wherein hard carbide cutter inserts (26) are metallurgically bonded into an interior core (28) of the cone through a cladding (34). The cladding (34) is bonded on to the exterior surface of the core (28) by a powder metallurgy process. The cladding (34) retains the inserts (26) in the core (28). A thin layer or coating (44) of a suitable metal, preferably nickel, is provided on the carbide insert (26) prior to mounting into the core (28). The coating (44) prevents degradation of the carbide through loss of carbon into the core (28) during the powder metallurgy process and accommodates mismatch of thermal expansion between the cutter insert (26) and the core (28). The interior of the cone is formed to provide bearing surfaces (34, 40) either by conventional techniques, or by powder metallurgy processes. Bearing surfaces formed in the interior of the core by powder metallurgy processes may be hard so as to permit an open bearing structure for the drill bit.