Disc Cutter for an Earth Boring System
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.