Enhanced Drill Bit Lubrication Apparatus and Method

Abstract

Lubricating nutating single cone drill bit ( 10, 100 ) includes bit shank ( 12, 112 ) with axially skewed journal ( 18, 118 ) rotatably retaining cutter body ( 22, 122 ). Bearings ( 26, 28, 30, 32; 126, 128, 130, 132 ) can enable rotation of cutter body ( 22, 122 ). Lubricant can be dispensed to a gap between journal ( 18, 118 ) and cutter body ( 22, 122 ) from lubricant chamber ( 76; 176, 179 ) having plunger ( 80; 180, 183 ), the gap bounded by first ( 66, 166 ) and second ( 68, 168 ) radial dynamic seals. Fluid passage ( 90, 190 ) extending through bit ( 10, 100 ) can communicate with fluid inlet port ( 88, 188 ) on proximal end ( 16, 116 ) of bit shank ( 12, 122 ). Fluid passage ( 90, 190 ) can further communicate with first fluid outlet port ( 98, 198 ) on distal end ( 36, 136 ) of journal ( 18, 118 ) and with second fluid outlet port ( 94, 194 ) formed on lateral portion of bit shank ( 12, 112 ).

1 . A lubricating nutating single cone drill bit comprising:
 a bit shank having a drill string connection on a proximal end and an axially skewed journal on a distal end;   at least one bearing rotatably retaining a cutter body on the axially skewed journal;   a plurality of cutter elements affixed to a distal end of the cutter body so that a tip of each cutter element is forward an intersection of a central axis of the bit shank and an axis of rotation of the cutter body and a first chordal distance to the tip of each cutter element from the axis of rotation of the cutter body is longer than a second chordal distance to said tip of each cutter element from the central axis of the bit shank;   a lubricant chamber in communication with a fluid inlet port and the at least one bearing; and   a plunger in the lubricant chamber to inhibit the ingress of an annulus fluid.   
   
   
       2 . The lubricating nutating single cone drill bit of  claim 1  further comprising a distal end of the axially skewed journal extending through an opening in the cutter body and a fluid outlet port in the distal end of the axially skewed journal in communication with a fluid passage in the bit shank, the fluid passage in communication with a second fluid inlet port in the proximal end of the bit shank. 
   
   
       3 . The lubricating nutating single cone drill bit of  claim 2  further comprising a second fluid outlet port on an exterior of the bit shank in communication with the fluid passage. 
   
   
       4 . The lubricating nutating single cone drill bit of  claim 1  wherein the at least one bearing comprises at least one ball bearing disposed between a first channel formed in the axially skewed journal and a second channel formed in an interior of the cutter body. 
   
   
       5 . The lubricating nutating single cone drill bit of  claim 1  wherein the axially skewed journal comprises a narrow portion at a distal end and a thrust shoulder adjacent the narrow portion. 
   
   
       6 . The lubricating nutating single cone drill bit of  claim 5  wherein the at least one bearing comprises a thrust bearing disposed between the thrust shoulder of the axially skewed journal and a thrust shoulder in an interior of the cutter body. 
   
   
       7 . The lubricating nutating single cone drill bit of  claim 6  wherein an aperture formed in the thrust shoulder of the axially skewed journal is in communication with the thrust bearing and the lubricant chamber to provide lubrication. 
   
   
       8 . The lubricating nutating single cone drill bit of  claim 6  wherein the at least one bearing further comprises at least one radial bearing disposed between the axially skewed journal and the cutter body. 
   
   
       9 . The lubricating nutating single cone drill bit of  claim 1  further comprising a first radial dynamic seal disposed between a proximal end of the cutter body and the axially skewed journal. 
   
   
       10 . The lubricating nutating single cone drill bit of  claim 9  further comprising a second radial dynamic seal disposed between the distal end of the cutter body and the axially skewed journal. 
   
   
       11 . The lubricating nutating single cone drill bit of  claim 4  further comprising a ball bearing passage connecting the first channel and the lubricant chamber to allow the insertion of the at least one ball bearing therethrough. 
   
   
       12 . The lubricating nutating single cone drill bit of  claim 11  further comprising a ball bearing retention sleeve disposed in the lubricant chamber adjacent the ball bearing passage to retain the at least one ball bearing between the first and the second channel and to allow passage of a lubricant from the lubricant chamber. 
   
   
       13 . The lubricating nutating single cone drill bit of  claim 3  wherein at least one of the fluid outlet ports comprises a jetting nozzle. 
   
   
       14 . The lubricating nutating single cone drill bit of  claim 1  wherein the plunger further comprises:
 a longitudinal bore extending therethrough; and   a plug sealed within the longitudinal bore.   
   
   
       15 . The lubricating nutating single cone drill bit of  claim 1  wherein the axially skewed journal is integral with the distal end of the bit shank. 
   
   
       16 . The lubricating nutating single cone drill bit of  claim 15  wherein the lubricant chamber and the fluid inlet port are in the bit shank. 
   
   
       17 . The lubricating nutating single cone drill bit of  claim 1  wherein the axially skewed journal is connected to the distal end of the bit shank. 
   
   
       18 . The lubricating nutating single cone drill bit of  claim 17  wherein the lubricant chamber is in the axially skewed journal and the fluid inlet port is on an exterior surface of the axially skewed journal. 
   
   
       19 . The lubricating nutating single cone drill bit of  claim 17  wherein the axially skewed journal is threadably engaged to the distal end of the bit shank. 
   
   
       20 . The lubricating nutating single cone drill bit of  claim 17  wherein the distal end of the bit shank comprises an axially skewed shaft. 
   
   
       21 . A method of assembling a lubricating nutating single cone drill bit comprising:
 providing a bit shank having a drill string connection on a proximal end and an axially skewed journal on a distal end;   rotatably retaining a cutter body on the axially skewed journal with at least one bearing, the cutter body having a plurality of cutter elements affixed to a distal end of the cutter body so that a tip of each cutter element is forward an intersection of a central axis of the bit shank and an axis of rotation of the cutter body and a first chordal distance to the tip of each cutter element from the axis of rotation of the cutter body is longer than a second chordal distance to said tip of each cutter element from the central axis of the bit shank; and   providing a lubricant chamber in communication with a fluid inlet port and the at least one bearing, a plunger disposed in the lubricant chamber.   
   
   
       22 . The method of  claim 21  further comprising disposing a lubricant into the lubricant chamber. 
   
   
       23 . The method of  claim 21  further comprising attaching the axially skewed journal to the distal end of the bit shank. 
   
   
       24 . The method of  claim 21  wherein the lubricant chamber and the fluid inlet port are in the bit shank. 
   
   
       25 . (canceled) 
   
   
       26 . The method of  claim 21  wherein the step of disposing the lubricant into the lubricant chamber further comprises:
 retaining the plunger adjacent the fluid inlet port;   disposing the lubricant through a longitudinal bore in the plunger; and   sealing the longitudinal bore in the plunger with a plug.   
   
   
       27 . (canceled)