Roller cone drill bit journal with asymmetric ball race and extended friction race

Abstract

The present disclosure relates to roller cone drill bit journals with asymmetric ball races and extended friction races. The disclosure also relates to methods of forming such journals, and methods of finishing these journals to produce finished journals with symmetric ball races.

1 . A roller cone drill bit journal comprising:
 a ball race;   a friction race; and   a protuberance that extends the friction race into an area to be occupied by the ball race in a finished journal and that renders the ball race in the journal asymmetric.   
     
     
         2 . The roller cone drill bit journal of  claim 1  further comprising a weld pool located on or within the protuberance. 
     
     
         3 . The roller cone drill bit journal of  claim 1  further comprising a weld pool and bearing material located on the friction race. 
     
     
         4 . The roller cone drill bit journal of  claim 1 , wherein the protuberance is circular or ovoid in cross-section. 
     
     
         5 . The roller cone drill bit journal of  claim 1 , wherein the protuberance is angular in cross-section. 
     
     
         6 . The roller cone drill bit journal of  claim 1 , wherein the protuberance extends into the ball race of the journal by up to 90% of the diameter of the ball race in the finished journal. 
     
     
         7 . The roller cone drill bit journal of  claim 1 , wherein the protuberance extends into the ball race of the journal by at least 0.05% of the diameter of the ball race in the finished journal. 
     
     
         8 . A method of forming a journal for a roller cone drill bit, the method comprising:
 forming a journal, comprising:
 a ball race; 
 a friction race: and 
 a protuberance that extends the friction race into an area to be occupied by the ball race in a finished journal and that renders the ball race in the journal asymmetric; 
   welding bearing material to the friction race using a weld pool; and   removing the protuberance and any weld pool or bearing material located on or in the protuberance to form a symmetric ball race.   
     
     
         9 . The method of  claim 8 , wherein the protuberance is circular or ovoid in cross-section. 
     
     
         10 . The method of  claim 8 , wherein the protuberance is angular in cross-section. 
     
     
         11 . The method of  claim 8 , wherein the protuberance extends into the ball race of the journal by up to 90% of the diameter of the ball race in the finished journal. 
     
     
         12 . The method of  claim 8 , wherein the protuberance extends into the ball race of the journal by at least 0.05% of the diameter of the ball race in the finished journal. 
     
     
         13 . The method of  claim 8 , wherein, during welding, the weld pool is placed on top of the protuberance. 
     
     
         14 . The method of  claim 8  wherein, during welding, the weld pool melts at least a portion of the protuberance. 
     
     
         15 . The method of  claim 8 , wherein, during welding, the weld pool replaces at least a portion of the protuberance. 
     
     
         16 . The method of  claim 8  wherein, during welding, the weld pool reaches a temperature sufficiently high to damage the ball race if the weld pool contacts the ball race. 
     
     
         17 . The method of  claim 8 , wherein, during welding, the weld pool does not contact the ball race. 
     
     
         18 . The method of  claim 8 , wherein the bearing material is at least 1% thicker along the at least an area of the friction race than in an otherwise identical bit with no protuberance. 
     
     
         19 . The method of  claim 8 , wherein the bearing material is at least 1% thicker along the entire friction race than in an otherwise identical bit with no protuberance. 
     
     
         20 . The method of  claim 8 , wherein removing the protuberance and any weld pool or bearing material located on or in the protuberance comprises machining.