System, method, and apparatus for contoured thrust surfaces between thrust washer and head for roller cone drill bit

Abstract

A thrust washer located between the thrust surfaces of the head and the cone of a drill bit allows for radial rotation between the cone, thrust washer, and head during drilling operations. The thrust washer also accommodates axial rotation between the cone and the head. The mating thrust surfaces between the thrust washer and the head are contoured to allow the thrust washer to rotate axially with the cone, and provide increased bearing contact between the thrust washer and the cone.

1 . An earth boring bit, comprising:
 a bit body having a bit leg;   a bearing head on the bit leg, the bearing head having a bearing head axis, a thrust face, and a cylindrical bearing surface concentric with the bearing head axis;   a roller cone having a cone axis and mounted to the bearing head for rotation relative to the bearing head, the roller cone having a thrust face; and   a thrust washer located between and in dynamic engagement with the thrust faces of the bearing head and roller cone, the thrust washer having a thrust face that is non-orthogonally contoured and complementary in shape to the thrust face of one of the bearing head and the roller cone to increase bearing contact between the thrust washer and the roller cone.   
   
   
       2 . A earth boring bit according to  claim 1 , wherein the thrust faces of the thrust washer and bearing head are formed on a spherical radius. 
   
   
       3 . A earth boring bit according to  claim 1 , wherein the thrust faces of the thrust washer and the bearing head are complementary in shape. 
   
   
       4 . A earth boring bit according to  claim 1 , wherein the thrust faces of the thrust washer and the roller cone are complementary in shape. 
   
   
       5 . A earth boring bit according to  claim 1 , wherein the thrust face of the thrust washer is convex, and the thrust face of the bearing head is concave. 
   
   
       6 . A earth boring bit according to  claim 1 , wherein the thrust face of the thrust washer is concave, and the thrust face of the bearing head is convex. 
   
   
       7 . A earth boring bit according to  claim 1 , wherein the thrust washer has a second thrust face that is flat and parallel to the thrust face of the other of the bearing head and the roller cone. 
   
   
       8 . A earth boring bit according to  claim 1 , wherein the thrust washer permits radial rotation between the roller cone and the thrust washer, and accommodates axial rotation between the roller cone and the bearing head with respect to the bearing head axis. 
   
   
       9 . A earth boring bit according to  claim 1 , wherein the thrust washer is formed from a material selected from the group consisting of stainless steel, bronze, carbide-containing materials, and diamond. 
   
   
       10 . A earth boring bit according to  claim 1 , further comprising a pin mounted to and extending between the thrust washer and one of the bearing head and the roller cone for preventing radial rotation therebetween. 
   
   
       11 . An earth boring bit, comprising:
 a bit body having a plurality of bit legs;   a bearing head on each of the bit legs to define a plurality of bearing heads, each bearing head having a bearing head axis, a thrust face, and a cylindrical bearing surface concentric with the bearing head axis;   a roller cone having a cone axis and mounted to each of the bearing heads to define a plurality of roller cones for rotation relative to the bearing heads, each roller cone having a thrust face; and   a thrust washer located between respective ones of the bearing heads and roller cones to define a plurality of thrust washers, the thrust washers being in dynamic engagement with the thrust faces of respective ones of the bearing heads and roller cones, and each thrust washer having a thrust face that is non-orthogonally contoured and complementary in shape to the thrust face of a respective one of the bearing heads to increase bearing contact between the thrust washer and the roller cone, such that the thrust washers permit radial rotation between the roller cones and the thrust washers, and accommodate axial rotation between the roller cones and the bearing heads with respect to the bearing head axes.   
   
   
       12 . A earth boring bit according to  claim 11 , wherein the thrust faces of the thrust washers and bearing heads are formed on a spherical radius. 
   
   
       13 . A earth boring bit according to  claim 11 , wherein the thrust faces of the thrust washers are convex, and the thrust faces of the bearing heads are concave. 
   
   
       14 . A earth boring bit according to  claim 11 , wherein the thrust faces of the thrust washers are concave, and the thrust faces of the bearing heads are convex. 
   
   
       15 . A earth boring bit according to  claim 11 , wherein the thrust washers have second thrust faces that are flat and parallel to the thrust faces of respective ones of the roller cones. 
   
   
       16 . A earth boring bit according to  claim 11 , wherein the thrust washers are formed from a material selected from the group consisting of stainless steel, bronze, carbide-containing materials, and diamond. 
   
   
       17 . A earth boring bit according to  claim 11 , further comprising a pin mounted to and extending between each of the thrust washers and respective ones of the bearing heads to define a plurality of pins for preventing radial rotation between respective ones of the thrust washers and bearing heads. 
   
   
       18 . An earth boring bit, comprising:
 a bit body having a plurality of bit legs;   a bearing head on each of the bit legs to define a plurality of bearing heads, each bearing head having a bearing head axis, a thrust face that is concave in shape, and a cylindrical bearing surface concentric with the bearing head axis;   a roller cone having a cone axis and mounted to each of the bearing heads to define a plurality of roller cones for rotation relative to the bearing heads, each roller cone having a thrust face; and   a thrust washer located between respective ones of the bearing heads and roller cones to define a plurality of thrust washers, the thrust washers being in dynamic engagement with the thrust faces of respective ones of the bearing heads and roller cones, and each thrust washer having a thrust face that is convex and complementary in shape to the thrust face of a respective one of the bearing heads to increase bearing contact between the thrust washer and the roller cone, such that the thrust washers permit radial rotation between the roller cones and the thrust washers, and accommodate axial rotation between the roller cones and the bearing heads with respect to the bearing head axis.   
   
   
       19 . A earth boring bit according to  claim 18 , wherein the thrust faces of the thrust washers and bearing heads are formed on a spherical radius, and the thrust washers have second thrust faces that are flat and parallel to the thrust faces of respective ones of the roller cones. 
   
   
       20 . A earth boring bit according to  claim 18 , wherein the thrust washers are formed from a material selected from the group consisting of stainless steel, bronze, carbide-containing materials, and diamond; and further comprising a pin mounted to and extending between each of the thrust washers and respective ones of the bearing heads to define a plurality of pins for preventing radial rotation between respective ones of the thrust washers and bearing heads.