Disc Cutter for an Earth Boring System

Abstract

In one aspect of the present invention a disc cutter for an earth boring system includes an axle and a sintered polycrystalline ceramic disc disposed about and forming a continuous perimeter around the axle. The disc cutter may be attached to a drill bit comprising a body, working face and plurality of blades. Another aspect of the present invention comprises a method of forming a disc cutter including providing a can of a generally cylindrical shape with a central axis, positioning a column of disposable material, carbide, and crystalline grains in such a manner so when put under high temperature and high pressure a compact in the shape of a disc cutter may be formed and a column from the center axis may be removed. Another method for forming a disc cutter comprises forming a plurality of compacts and bonding the compacts together in a generally toroidal shape.

1 . A method of forming a disc cutter, comprising:
 providing a first can comprising a generally cylindrical shape and a central axis;   positioning a first carbide substrate inside and coaxial with the first can;   disposing crystalline grains inside the first can and forming a continuous perimeter around the first carbide substrate;   applying high temperature and high pressure to the first can to form a first compact; and   removing a column from the first compact along the central axis.   
     
     
         2 . The method of  claim 1 , wherein the first carbide substrate comprises an axially hollow region. 
     
     
         3 . The method of  claim 2 , wherein a disposable material is disposed within the axially hollow region of the first carbide substrate. 
     
     
         4 . The method of  claim 3 , wherein the disposable material comprises salt, silicon oxide, aluminum oxide, or tungsten carbide. 
     
     
         5 . The method of  claim 1 , wherein the first can comprises an axially hollow region. 
     
     
         6 . The method of  claim 5 , wherein a disposable material is disposed within the axially hollow region of the first can. 
     
     
         7 . The method of  claim 1 , wherein removing a column comprises blasting, abrasive lapping, abrasive grinding, or electric discharge machining. 
     
     
         8 . The method of  claim 1 , further comprising:
 providing a second can comprising a generally cylindrical shape and a central axis;   positioning a column of disposable material inside and coaxial with the second can;   positioning a second carbide substrate comprising a toroidal shape coaxial with the second can and encircling the second column;   disposing crystalline grains inside the second can and intermediate the second carbide substrate and the column of disposable material;   applying high temperature and high pressure to the second can to form a second compact; and   bonding the first carbide substrate to the second carbide substrate.   
     
     
         9 . The method of  claim 8 , wherein the bonding the first carbide substrate to the second carbide substrate comprises:
 heating the first compact causing it to expand;   depositing the second compact within the first compact; and   cooling the first compact causing it to shrink around the second compact.   
     
     
         10 . A method of forming a disc cutter, comprising:
 providing a can comprising a generally cylindrical shape and a central axis;   positioning a column of disposable material along the axis of the can;   positioning a carbide substrate comprising a toroidal shape coaxial with the can and encircling the column;   disposing crystalline grains inside the can and intermediate the carbide substrate and the column of disposable material;   disposing crystalline grains inside the can and forming a continuous perimeter around the carbide substrate;   applying high temperature and high pressure to the can to form a compact; and   removing the column from the compact.   
     
     
         11 . A method of forming a disc cutter, comprising:
 providing a can;   disposing crystalline grains inside the can;   positioning a carbide substrate adjacent the crystalline grains;   applying high temperature and high pressure to the can to form a compact;   repeating the preceding steps to form a plurality of compacts; and   bonding the compacts together.   
     
     
         12 . The method of  claim 11 , further comprising removing a column from a center of the bonded compacts. 
     
     
         13 . The method of  claim 12 , wherein removing the column comprises blasting, abrasive lapping, abrasive grinding, or electric discharge machining. 
     
     
         14 . The method of  claim 11 , wherein the bonding the compacts together comprises bonding the carbide substrates of each compact. 
     
     
         15 . The method of  claim 14 , wherein the bonding the compacts together further comprises brazing the carbide substrates of each compact. 
     
     
         16 . The method of  claim 11 , wherein the bonding the compacts together comprises bonded the compacts such that they form a generally cylindrical shape. 
     
     
         17 . The method of  claim 16 , wherein the cylindrical shape is axially hollow. 
     
     
         18 . The method of  claim 17 , wherein the compacts each comprise a sintered polycrystalline ceramic external layer which are flush with each other after brazing. 
     
     
         19 . The method of  claim 11 , wherein the can comprises a generally annular sector shape. 
     
     
         20 . The method of  claim 19 , wherein the generally annular sector shape is formed by pressing the can around the carbide substrate.