Downhole tool bearing system containing diamond enhanced materials

Abstract

Downhole tool bearings are provided with diamond enhanced materials. The diamond enhanced materials comprise diamond grains in a matrix of tungsten or silicon carbide. A brazed diamond grit or diamond particles coated with a reactive braze may be utilized for bearing applications. Bearing rings formed at least in part with diamond enhanced material are installed on at least one of the bearing pin journal, the nose and the cone cavity. The bearing rings may be continuous rings or partial rings and attached to the journal pin or cone cavity. These may include thrust bearings, rollers, roller race, balls and ball races made of diamond enhanced material. These bearing surfaces also are formed at least in part with diamond enhanced material and attached to portions of the journal or cone bearing surfaces.

1 . A downhole tool for subterranean mining applications, comprising:
 a body having a bearing pin extending along an axis, the bearing pin having a journal surface and a nose surface with a smaller diameter than that of the journal surface;   a rotatable element rotatably mounted to the bearing pin and having a cavity slidingly engaging the journal and nose surfaces; and   a diamond enhanced bearing system between the bearing pin and the rotatable element having at least one load carrying bearing surface formed at least in part with diamond enhanced material.   
   
   
       2 . A downhole tool according to  claim 1 , wherein the diamond enhanced material comprises one of:
 diamond grains in a matrix of tungsten carbide;   a high temperature, high pressure sintered silicon bonded polycrystalline diamond;   a low pressure, low concentration diamond enhanced polycrystalline material;   an aluminum nitride intermetallic bonded diamond and carbide composite;   a brazed diamond grit; and   diamond particles coated with a reactive braze.   
   
   
       3 . A downhole tool according to  claim 1 , wherein the diamond enhanced material comprises 30% to 70% diamond by volume, with a grain size of 5 to 250 microns. 
   
   
       4 . A downhole tool according to  claim 1 , wherein the diamond enhanced material comprises diamond enhanced tungsten carbide and is about 5% to 25% diamond by volume. 
   
   
       5 . A downhole tool according to  claim 1 , wherein the diamond enhanced material is unsintered and has an open porosity of about 9%, and a principle binder phase comprising βSiC with some free Si. 
   
   
       6 . A downhole tool according to  claim 1 , wherein the diamond enhanced material is one of diamond enhanced WC and diamond film. 
   
   
       7 . A downhole tool according to  claim 1 , wherein the bearing surface has a diamond enhanced bearing surface installed on at least one of the journal, the nose and the cavity. 
   
   
       8 . A downhole tool according to  claim 7 , wherein the diamond enhanced bearing surface comprises a plurality of bearing rings that are formed at least in part with diamond enhanced material. 
   
   
       9 . A downhole tool according to  claim 8 , wherein the bearing rings are installed on the journal surface, the nose surface and in the cavity. 
   
   
       10 . A downhole tool according to  claim 1 , wherein the bearing surface is attached with one of brazing, soldering, adhesives and mechanical locking by shrink fitting, pinning, splinning or keyways. 
   
   
       11 . A downhole tool according to  claim 1 , wherein the bearing surface is a partial ring and discontinuous. 
   
   
       12 . A downhole tool according to  claim 1 , wherein the bearing surface comprises ring sections. 
   
   
       13 . A downhole tool according to  claim 1 , wherein the bearing surface comprises at least one of a thrust bearing made of diamond enhanced material, a roller, a roller race surface, a ball and a ball race surface made of diamond enhanced material. 
   
   
       14 . A downhole tool according to  claim 1 , wherein channels are formed in the bearing surface. 
   
   
       15 . A rolling cone earth boring drill bit for attachment to a drill string, comprising:
 a body having a bit leg extending therefrom with a bearing pin extending along an axis, the bearing pin having a main journal surface and a nose surface with a smaller diameter than that of the main journal surface;   a cone rotatably mounted to the bearing pin and having a plurality of cutting elements, a cavity slidingly engaging the main journal and nose surfaces; and   a diamond enhanced bearing system between the bearing pin and the cone comprising at least one bearing ring formed at least in part with diamond enhanced material.   
   
   
       16 . A rolling cone drill bit according to  claim 15 , wherein the diamond enhanced material comprises one of:
 diamond grains in a matrix of tungsten carbide;   a high temperature, high pressure sintered silicon bonded polycrystalline diamond;   a low pressure, low concentration diamond enhanced polycrystalline material;   an aluminum nitride intermetallic bonded diamond and carbide composite;   a brazed diamond grit; and   diamond particles coated with a reactive braze.   
   
   
       17 . A rolling cone drill bit according to  claim 15 , wherein the diamond enhanced material comprises diamond enhanced tungsten carbide and is about 5% to 25% diamond by volume; and
 the diamond enhanced material is unsintered and has an open porosity of about 9%, and a principle binder phase comprising βSiC with some free Si having 30% to 70% diamond by volume, with a grain size of 5 to 250 microns.   
   
   
       18 . A rolling cone drill bit according to  claim 15 , wherein the diamond enhanced material is one of diamond enhanced WC and diamond film. 
   
   
       19 . A rolling cone drill bit according to  claim 15 , wherein the bearing ring is installed on at least one of the main journal surface, the nose surface and the cavity of the cone. 
   
   
       20 . A rolling cone drill bit according to  claim 15 , wherein the bearing ring comprises a plurality of bearing rings that are formed at least in part with diamond enhanced material. 
   
   
       21 . A rolling cone drill bit according to  claim 20 , wherein the bearing rings are installed on both the main journal surface, the nose surface and on the cavity of the cone. 
   
   
       22 . A rolling cone drill bit according to  claim 15 , wherein the bearing ring is attached with one of brazing, soldering, adhesives and mechanical locking by shrink fitting, pinning, splinning or keyways 
   
   
       23 . A rolling cone drill bit according to  claim 15 , wherein the bearing ring is a partial ring and discontinuous. 
   
   
       24 . A rolling cone drill bit according to  claim 15 , wherein the bearing ring comprises ring sections, and channels are formed in the ring sections. 
   
   
       25 . A rolling cone drill bit according to  claim 15 , wherein the bearing ring comprises at least one of a thrust bearing made of diamond enhanced material, a roller, a roller race surface, a ball and a ball race surface made of diamond enhanced material.