Cutting structure for single roller cone drill bit

Abstract

A roller cone drill bit is disclosed which includes a bit body adapted to be coupled to a drill string. A bearing journal depends from the bit body. A single roller cone is rotatably attached to the bearing journal. The roller cone is formed from steel and includes a plurality of cutting elements disposed at selected positions about the cone. At least one of the cutting elements has an extending body which has a first end coupled to the roller cone and a distal end extending away from the cone. The extending body is formed from steel. A super hard element is coupled to the distal end of the extending body to form a super hard cutting face for the cutting element.

1 . A drill bit, comprising: 
 a single rotatable cone; and    at least one cutting element disposed on the cone, the at least one cutting element comprising: 
 an extending body formed of steel and having a first end connected to the cone and a distal end extending away from the cone,  
 a super hard element coupled to the distal end of the extending body and forming at least part of a cutting surface of the cutting element.  
   
   
   
       2 . The bit of  claim 1 , wherein the extending body comprises a milled steel tooth formed on the cone.  
   
   
       3 . The bit of  claim 1 , wherein the extending body comprises an insert body disposed in a socket formed in the cone.  
   
   
       4 . The bit of  claim 1 , wherein the at least one cutting element is disposed in a bottom contacting zone on the cone.  
   
   
       5 . The bit of  claim 1 , wherein the extending body has an extension length of at least about 12 mm.  
   
   
       6 . The bit of  claim 1 , wherein the super hard element extends from the distal end of the extending body by at least about 2 mm.  
   
   
       7 . The bit of  claim 1 , wherein the super hard element comprises at least one selected from the group of diamond, cubic boron nitride, and carbide.  
   
   
       8 . The bit of  claim 1 , wherein the super hard element comprises a body of super hard material bonded to a substrate.  
   
   
       9 . The bit of  claim 1 , wherein the super hard element is press fit in a socket formed in the extending body.  
   
   
       10 . The bit of  claim 1 , wherein the super hard element is coupled to the extending body by brazing.  
   
   
       11 . The bit of  claim 1 , wherein the super hard element comprises a generally convex shaped surface.  
   
   
       12 . The bit of  claim 1 , wherein the extended body is tapered at the distal end.  
   
   
       13 . The bit of  claim 1 , further comprising a layer of hardfacing disposed on at least a portion of the extending body.  
   
   
       14 . The bit of  claim 1 , further comprising: 
 a bit body adapted to be coupled to a drill string; and    a bearing journal depending from the bit body,    wherein the single roller cone is formed of steel and rotatably mounted on the bearing journal, the at least one cutting element is disposed on the roller cone in a bottom contacting zone, and the extending body of the at least one cutting element comprises a milled steel tooth formed on the cone.    
   
   
       15 . The bit of  claim 13 , wherein the super hard element is disposed in a socket formed at the distal end of the extending body, the extending body extends from the cone surface by at least about 10 mm, and the super hard element extends from the distal end of the extending body by at least about 2 mm.  
   
   
       16 . The bit of  claim 1 , further comprising: 
 a bit body adapted to be coupled to a drill string;    a bearing journal depending from the bit body,    wherein the single roller cone is formed of steel and rotatably mounted on the bearing journal, and the at least one cutting element is disposed in a bottom contacting zone on the cone, the at least one cutting element comprising an insert disposed in a socket formed on the cone.    
   
   
       17 . The bit of  claim 16 , wherein the super hard element is disposed in a socket formed at the distal end of the extending body, the extending body extends from the cone surface by at least about 10 mm and the super hard element extends from the distal end of the extending body by at least about 2 mm.  
   
   
       18 . A method for making a drill bit, comprising: 
 rotationally coupling a single roller cone to a journal depending from a drill bit body,    providing at a selected position on the cone at least one cutting element having an extending body formed from steel and a super hard element coupled to a distal end of the extending body forming at least a part of an outer surface of the cutting element.    
   
   
       19 . The method of  claim 18 , further comprising covering at least a portion of the outer surface of the extended body with hardfacing material.  
   
   
       20 . A drill bit, comprising: 
 a single rotatable cone; and    a plurality of cutting elements disposed on the cone, the plurality of cutting elements comprising a first set of cutting elements disposed in a first region of the cone and a second set of cutting elements disposed in a second region of the cone, wherein at least one of the cutting elements in the first region comprises: 
 an extending body formed of steel and having a first end connected to the cone and a distal end extending away from the cone,  
 a super hard element coupled to the distal end of the extending body and forming at least part of a cutting surface of the cutting element.