Drill bit with seal having spheres in a matrix seal material

Abstract

A drill bit can include a seal which seals against a drill bit surface, the seal including a matrix seal material and a plurality of hollow spheres in the matrix seal material. Another drill bit can include a seal with a matrix seal material, spheres being more dense in a portion of the matrix seal material as compared to in the matrix seal material outside of the portion, and the portion of the matrix seal material being in dynamic sealing contact with a drill bit surface during operation. A drill bit can include a seal between a cone and a journal, the seal comprising a matrix seal material and a plurality of spheres in the matrix seal material, the matrix seal material comprising nitrile.

What is claimed is: 
     
         1 . A drill bit, comprising:
 a seal which seals against a drill bit surface, the seal comprising a matrix seal material and a plurality of hollow spheres in the matrix seal material.   
     
     
         2 . The drill bit of  claim 1 , wherein the hollow spheres comprise hollow microspheres. 
     
     
         3 . The drill bit of  claim 1 , wherein the hollow spheres comprise hollow glass spheres. 
     
     
         4 . The drill bit of  claim 1 , wherein the hollow spheres are more dense in a portion of the matrix seal material, as compared to in the matrix seal material outside of the portion. 
     
     
         5 . The drill bit of  claim 4 , wherein the portion of the matrix seal material contacts a journal of the drill bit. 
     
     
         6 . The drill bit of  claim 4 , wherein the portion of the matrix seal material contacts a cone of the drill bit. 
     
     
         7 . The drill bit of  claim 4 , wherein the portion of the matrix seal material is in dynamic contact with at least one of a journal of the drill bit and a cone of the drill bit during operation. 
     
     
         8 . The drill bit of  claim 1 , wherein the matrix seal material comprises at least one of nitrile and hydrogenated nitrile. 
     
     
         9 . The drill bit of  claim 1 , wherein the hollow spheres have a hardness less than a hardness of at least one of a journal of the drill bit and a cone of the drill bit. 
     
     
         10 . A drill bit, comprising:
 a seal including a matrix seal material, spheres being more dense in a portion of the matrix seal material as compared to in the matrix seal material outside of the portion, and the portion of the matrix seal material being in dynamic sealing contact with a drill bit surface during operation.   
     
     
         11 . The drill bit of  claim 10 , wherein the spheres comprise hollow spheres. 
     
     
         12 . The drill bit of  claim 10 , wherein the portion of the matrix seal material contacts a journal of the drill bit. 
     
     
         13 . The drill bit of  claim 10 , wherein the portion of the matrix seal material contacts a cone of the drill bit. 
     
     
         14 . The drill bit of  claim 10 , wherein the matrix seal material comprises at least one of nitrile and hydrogenated nitrile. 
     
     
         15 . The drill bit of  claim 10 , wherein the spheres have a hardness less than a hardness of the drill bit surface. 
     
     
         16 . The drill bit of  claim 10 , wherein the seal seals between a cone and a journal of the drill bit. 
     
     
         17 . The drill bit of  claim 16 , wherein the portion of the matrix seal material is in dynamic contact with at least one of the journal and the cone during operation. 
     
     
         18 . The drill bit of  claim 10 , wherein the spheres comprise hollow microspheres. 
     
     
         19 . The drill bit of  claim 10 , wherein the spheres comprise hollow glass spheres. 
     
     
         20 . A drill bit, comprising:
 a journal;   a cone which rotates about the journal; and   a seal between the cone and the journal, the seal comprising a matrix seal material and a plurality of spheres in the matrix seal material, the matrix seal material comprising nitrile.   
     
     
         21 . The drill bit of  claim 20 , wherein the spheres comprise hollow microspheres. 
     
     
         22 . The drill bit of  claim 20 , wherein the spheres comprise hollow glass spheres. 
     
     
         23 . The drill bit of  claim 20 , wherein the spheres are confined to a portion of the matrix seal material. 
     
     
         24 . The drill bit of  claim 23 , wherein the portion of the matrix seal material contacts the journal. 
     
     
         25 . The drill bit of  claim 23 , wherein the portion of the matrix seal material contacts the cone. 
     
     
         26 . The drill bit of  claim 23 , wherein the portion of the matrix seal material is in dynamic contact with at least one of the journal and the cone during operation. 
     
     
         27 . The drill bit of  claim 20 , wherein the nitrile comprises hydrogenated nitrile. 
     
     
         28 . The drill bit of  claim 20 , wherein the spheres have a hardness less than a hardness of at least one of a journal of the drill bit and a cone of the drill bit.