Superhard insert and an earth boring tool comprising same

Abstract

A superhard insert for a rotary earth borer tool comprises a cutter end having a peripheral cutter edge, at least part of the peripheral cutter edge being defined by a plurality of edges of a plurality of alternate hard and superhard regions. The edges of the superhard regions are arranged spaced apart from each other and are separated by edges of hard regions. The hardness of each hard region is at most 50% of the hardness of each superhard region.

1 . A superhard insert for a rotary earth borer tool, comprising a cutter end having a peripheral cutter edge, at least part of the peripheral cutter edge being defined by a plurality of edges of a plurality of alternate hard and superhard regions, the edges of the superhard regions arranged spaced apart from each other and separated by edges of hard regions; the hardness of each hard region being at most 50% of the hardness of each superhard region. 
     
     
         2 . A superhard insert as claimed in  claim 1 , wherein the cutter end comprises a hard central region remote from the peripheral cutter edge, the central hard region including a raised or boss portion operable to deflect chips formed of a material being bored or degraded away from the cutter end. 
     
     
         3 . A superhard insert according to  claim 1 , wherein at least one superhard region has an identification marking. 
     
     
         4 . A superhard insert according to  claim 1 , comprising a plurality of spoke formations projecting radially outward, each spoke comprising a superhard structure. 
     
     
         5 . A superhard insert according to  claim 1 , wherein one or more or each of the at least one of the superhard regions has generally converging or generally diverging sides when viewed in a plan view of the cutter end. 
     
     
         6 . A superhard insert according to  claim 1 , wherein the Vickers hardness of each superhard region is at least 40 GPa. 
     
     
         7 . A superhard insert according to  claim 1 , wherein one or more or each of the superhard regions comprises PCD material. 
     
     
         8 . A superhard insert according to  claim 1 , wherein the at least one of the plurality of superhard regions comprises PCD material comprising diamond grains having mean diamond grain contiguity of at least about 60.5 percent. 
     
     
         9 . A superhard insert according to  claim 1 , wherein the at least one of the plurality of superhard regions comprises PCD material having an interstitial mean free path of at least 0.05 microns and at most 1 micron. 
     
     
         10 . A rotary drill bit comprising a superhard insert as claimed in  claim 1 . 
     
     
         11 . An earth boring tool comprising rotary drill bit as claimed in  claim 10 .