Helical chisel insert for rock bits

Abstract

An insert for an earth boring drill bit, such as a PDC rock bit or a roller cone rock bit, is provided. The insert includes a base integrally joined to a top section, the top section having a first flank that curves in a substantially helical manner about a longitudinal axis of the insert to join a crest.

1 . An insert for an earth boring drill bit having a base integrally joined to a top section, the top section having a first flank that curves in a substantially helical manner about a longitudinal axis of the insert to join a crest. 
   
   
       2 . The insert of  claim 1 , further comprising a polycrystalline diamond compact (PDC) insert. 
   
   
       3 . The insert of  claim 2 , wherein the earth boring device is a PDC rock bit. 
   
   
       4 . The insert of  claim 1 , further comprising a second flank that curves in a substantially helical manner about the longitudinal axis of the insert to join the crest. 
   
   
       5 . The insert of  claim 4 , further comprising a degree of twist in a range from about  0 ° to about 90°. 
   
   
       6 . The insert of  claim 5 , wherein the flanks curve in either a substantially clockwise manner or a substantially counterclockwise manner. 
   
   
       7 . The insert of  claim 6 , further comprising a tungsten carbide insert (TCI). 
   
   
       8 . The insert of  claim 6 , further comprising a diamond enhanced TCI. 
   
   
       9 . The insert of  claim 6 , wherein the earth boring device is a rotary cone rock bit. 
   
   
       10 . The insert of  claim 6 , wherein the earth boring device is a PDC rock bit. 
   
   
       11 . The insert of  claim 5 , further comprising a timing mark. 
   
   
       12 . A drill bit for boring an earth formation, the drill bit comprising a plurality of helical chisel inserts. 
   
   
       13 . The drill bit of  claim 12 , wherein the drill bit further comprises a PDC drill bit. 
   
   
       14 . The drill bit of  claim 12 , further comprising a rotary cone rock bit having a plurality of cutters for plowing the formation in a selected direction, wherein each cutter has a circumferential outermost heel row with helical chisel inserts positioned thereon. 
   
   
       15 . The drill bit of  claim 14 , wherein each cutter has a circumferential second row with helical chisel inserts positioned thereon 
   
   
       16 . The drill bit of  claim 15 , wherein the helical chisel insert further comprises a base integrally joined to a top section, the top section having a leading flank and a trailing flank that curve in a substantially helical manner about a longitudinal axis of the insert to join an elongated crest. 
   
   
       17 . The drill bit of  claim 16 , wherein the elongated crests of the helical chisel inserts positioned on the heel row are substantially in line with the direction of plowing of the formation. 
   
   
       18 . The drill bit of  claim 17 , wherein the elongated crests of the helical chisel inserts positioned on the second row are substantially in line with the direction of plowing of the formation. 
   
   
       19 . The drill bit of  claim 16 , wherein a broad side of the elongated crests of the helical chisel inserts positioned on the heel row substantially face the direction of plowing of the formation. 
   
   
       20 . The drill bit of  claim 19 , wherein a broad side of the elongated crests of the helical chisel inserts positioned on the second row substantially face the direction of plowing of the formation. 
   
   
       21 . A method for drilling an earth formation, comprising the steps of:
 providing a rotary cone cutter having a plurality of cutters, wherein each cutter has an axis of rotation for plowing the formation in a direction, and comprises an outermost heel row and a second row;   positioning a first set of helical chisel inserts on the heel row; and   positioning a second set of helical chisel inserts on the second row, wherein the helical chisel inserts each comprise a base integrally joined to a top section, the top section having a leading flank and a trailing flank that curve in a substantially helical manner about a longitudinal axis of the insert to join an elongated crest.   
   
   
       22 . The method of  claim 21 , further comprising the steps of:
 aligning the elongated crests of the first set of helical chisel inserts at an azimuth direction from about 30 degrees to about 60 degrees from the axis of rotation of the cutter; and   aligning the elongated crests of the second set of helical chisel inserts at an azimuth direction from about 300 degrees to about 330 degrees from the axis of rotation of the cutter.   
   
   
       23 . The method of  claim 21 , further comprising the steps of:
 aligning the elongated crests of the first set of helical chisel inserts at an azimuth direction from about 300 degrees to about 330 degrees from the axis of rotation of the cutter; and   aligning the elongated crests of the second set of helical chisel inserts at an azimuth direction from about 30 degrees to about 60 degrees from the axis of rotation of the cutter.   
   
   
       24 . The method of  claim 21 , further comprising the steps of:
 aligning the elongated crests of the first set of helical chisel inserts and the second set of helical inserts substantially in line with the direction of plowing of the formation.   
   
   
       25 . The method of  claim 21 , further comprising the steps of:
 aligning the elongated crests of the first set of helical chisel inserts and the second set of helical chisel inserts substantially perpendicular to the direction of plowing of the formation.