Spirally and/or radially serrated superhard cutter

Abstract

A cutter for use with a drill bit includes: a substrate for mounting in a pocket of the drill bit and made from a cermet material; and a cutting table made from a polycrystalline superhard material, mounted to the substrate at an interface, having a working face opposite from the interface, and having at least four serrations formed in the working face and a side thereof. Each serration has a pair of base edges and an apical edge extending above the base edges at the side of the cutting table. Each edge extends radially or spirally from the side of the cutting table to a central portion of the working face. The edges all converge at the center of the working face.

1 . A cutter for use with a drill bit, comprising:
 a substrate for mounting in a pocket of the drill bit and made from a cermet material; and   a cutting table made from a polycrystalline superhard material, mounted to the substrate at an interface, having a working face opposite from the interface, and having at least four serrations formed in the working face and a side thereof,   wherein:
 each serration has a pair of base edges and an apical edge extending above the base edges at the side of the cutting table, 
 each edge extends radially or spirally from the side of the cutting table to a central portion of the working face, and 
 the edges all converge at the center of the working face. 
   
     
     
         2 . The cutter of  claim 1 , wherein a maximum height of the apical edges relative to the respective base edges ranges between one-tenth of a millimeter and one millimeter. 
     
     
         3 . The cutter of  claim 1 , wherein an apical angle of each serration ranges between one-hundred degrees and one-hundred seventy degrees. 
     
     
         4 . The cutter of  claim 1 , wherein:
 each edge extends from the side of the cutting table to a center of the working face, and   the apical edges are coplanar with the center of the working face.   
     
     
         5 . The cutter of  claim 1 , wherein:
 the cutting table has at least ten of the serrations, and   the serrations extend around an entirety of the side of the cutting table.   
     
     
         6 . The cutter of  claim 1 , wherein each serration shares the base edges with adjacent serrations. 
     
     
         7 . The cutter of  claim 1 , wherein each serration has a triangular front face and triangular side faces. 
     
     
         8 . The cutter of  claim 1 , wherein the substrate has a keyway formed in an edge thereof for orienting or indexing the serrations. 
     
     
         9 . The cutter of  claim 1 , wherein each apical edge is sharp. 
     
     
         10 . The cutter of  claim 1 , wherein each apical edge is rounded and has a radius ranging between one-eighth and three-fourths of a maximum width of the respective serration. 
     
     
         11 . The cutter of  claim 1 , wherein the substrate has a bump formed in or mounted to a back face thereof for orienting or indexing the serrations. 
     
     
         12 . A bit for drilling a wellbore, comprising:
 a shank having a coupling formed at an upper end thereof;   a body mounted to a lower end of the shank; and   a cutting face forming a lower end of the bit and comprising:
 a blade protruding from the body; and 
 the cutter of  claim 1 , 
   wherein the substrate is mounted in the pocket formed in the blade.   
     
     
         13 . The bit of  claim 12 , wherein the cutting face further comprises a backup shear cutter mounted in a second pocket formed in the blade. 
     
     
         14 . The cutter of  claim 1 , wherein each edge extends radially from the side of the cutting table to a center of the working face. 
     
     
         15 . The cutter of  claim 1 , wherein each edge extends spirally from the side of the cutting table to a center of the working face. 
     
     
         16 . The cutter of  claim 1 , wherein each edge extends spirally for a first portion of the respective serration and radially for a second portion of the respective serration. 
     
     
         17 . The cutter of  claim 16 , wherein:
 each first portion and the respective second portion are connected at a respective junction, and   each junction is staggered relative to junctions of adjacent serrations.   
     
     
         18 . The cutter of  claim 1 , wherein:
 the central portion of the working face is recessed relative to the side of the working face, and   each edge extends radially or spirally and declines vertically from the side to the central portion of the working face.   
     
     
         19 . The cutter of  claim 18 , wherein:
 the apical edges have a first maximum height relative to the base edges and a second maximum height relative to the central portion, and   the second maximum height is greater than the first maximum height.   
     
     
         20 . The cutter of  claim 18 , wherein each edge extends radially from the side of the cutting table to the central portion of the working face. 
     
     
         21 . The cutter of  claim 18 , wherein each edge extends spirally from the side of the cutting table to the central portion of the working face. 
     
     
         22 . The cutter of  claim 18 , wherein each edge extends spirally for a first portion of the respective serration and radially for a second portion of the respective serration. 
     
     
         23 . The cutter of  claim 18 , wherein the cutting table further has a chip-breaker formed in the central portion of the working face and having a jagged and non-planar periphery. 
     
     
         24 . The cutter of  claim 23 , wherein:
 the serrations are outer serrations, and   the cutting table further has at least four inner serrations are formed in the chip-breaker.   
     
     
         25 . The cutter of  claim 24 , wherein:
 an inner portion of the chip-breaker is recessed relative to the periphery thereof, and   the inner serrations extend radially and decline vertically from the periphery to the inner portion of the chip-breaker.   
     
     
         26 . The cutter of  claim 25 , wherein the inner serrations extend radially from the side of the cutting table to the inner portion of the chip-breaker. 
     
     
         27 . The cutter of  claim 25 , wherein the inner serrations extend spirally from the side of the cutting table to the inner portion of the chip-breaker. 
     
     
         28 . The cutter of  claim 25 , wherein the inner serrations extend spirally for a first portion thereof and radially for a second portion thereof.