Anti-Tracking Feature for Rock Bits

Abstract

The harmful effects of tracking are reduced for a drill bit having roller cones with at least one of the outermost rows of active teeth containing one or more teeth having a height that does not extend to the height of at least one of the outermost rows on another roller cone on the bit. The crest on this tooth may have a length in a circumferential direction that is wider than an overall width of the tooth in the outer to inner direction. The invention may be used on any cutter row, not just the outermost row. The design may be used on a different roller cone or row, or more than one cutter row. The anti-tracking feature may be located between the leading and trailing edges of the tooth on one or more roller cones.

1 .- 25 . (canceled) 
     
     
         26 . An earth boring bit, comprising:
 a body having at least one bearing pin with an axis;   a cone rotatably mounted to the bearing pin, the cone having a cutting surface;   a disk fanned on an outward portion of the cutting surface of the cone, the disk having a circular edge extending circumferentially around the cutting surface of the cone concentric with the axis, the disk having slots formed therein spaced around a circumference of disk and extending generally radially relative to the axis, defining individual heel row teeth; and   an adjacent row of teeth machined on the cutting surface of the cone adjacent and inward from the heel row teeth, each of the teeth in the adjacent row being generally pyramidal in configuration.   
     
     
         27 . The bit according to  claim 26 , wherein each of the teeth of the adjacent row has a leading flank and a trailing flank sloping toward each other to define a crest. 
     
     
         28 . The bit according to  claim 26 , wherein each of the slots has opposed side walls that are substantially parallel with each other. 
     
     
         29 . The bit according to  claim 26 , wherein a circumferential width of each of the heel row teeth measured at the edge of the disk is greater than a circumferential width of each of the heel row teeth measured at a base of the slots. 
     
     
         30 . The bit according to  claim 26 , wherein the edge of the disk defines a circumferentially extending crest of each of the heel row teeth. 
     
     
         31 . The bit according to  claim 26 , wherein the disk has a conical outer surface, and the slots extend into the outer surface to define outer flanks for each of the heel row teeth. 
     
     
         32 . The bit according to  claim 26 , wherein the disk has a conical inner surface, and the slots extend into the inner surface to define inner flanks for each of the heel row teeth. 
     
     
         33 . An earth boring bit, comprising:
 a body having at east a plurality of bearing pins, each having a bearing pin axis;   first, second and third cones, each rotatably mounted on one of the bearing pins, each of the cones having a cutting surface;   a disk formed on an outward portion of the cutting surface of the first cone, the disk having a circular edge extending circumferentially around the cutting surface of the cone concentric with the axis, the disk having slots formed therein spaced around a circumference of the disk and extending generally radially relative to the axis, defining individual first cone heel row teeth;   the edge of the disk defining a circumferentially extending crest for each of the first cone heel row teeth, each of the first cone heel row teeth having a greater circumferential width measured at the crest than at bases of the slots;   the slots in the disk defining leading and trailing flanks for each of the first cone heel row teeth;   an adjacent row of teeth machined on the cutting surface of the first cone adjacent and inward from the first cone heel row teeth, each of the teeth in the adjacent row being generally pyramidal in configuration; and   the second and the third cone having heel row teeth with a circumferential width measured at a crest that is less that a circumferential width measured at a base of each of the heel row teeth of the second and third cones.   
     
     
         34 . The bit according to  claim 33 , wherein a height of each of the heel row teeth of the second and third cones, measured from the bases to the crests, is greater than a height of the first cone heel row teeth, measured from the bases to the crests of the heel row teeth. 
     
     
         35 . The bit according to  claim 33 , wherein the crests of the heel row teeth of the second cone have a length extending from an inward to outward direction that is greater than a circumferentially extending width. 
     
     
         36 . The bit according to  claim 33 , wherein each of the slots has opposed side walls that are substantially parallel with each other. 
     
     
         37 . The bit according to  claim 33 , wherein the disk has a conical outer surface, and the slots extend into the outer surface to define outer flanks for each of the first cone heel row teeth. 
     
     
         38 . The bit according to  claim 33 , wherein the disk has a conical inner surface, and the slots extend into the inner surface to define inner flanks for each of the first cone heel row teeth. 
     
     
         39 . An earth boring bit, comprising:
 a body having at least a plurality of bearing pins, each having a bearing pin axis;   first, second and third cones, each rotatably mounted on one of the bearing pins, each of the cones having a cutting surface;   a disk formed on an outward portion of the cutting surface of the first cone, the disk having a circular edge extending circumferentially around the cutting surface of the cone concentric with the axis, the disk having slots formed therein spaced around a circumference of the disk and extending generally radially relative to the axis;   an adjacent row of teeth machined on the cutting surface of the first cone adjacent and inward from the disk, each of the teeth in the adjacent row being generally pyramidal in configuration;   the second and the third cone having first and second cone heel row teeth, respectively;   the second and third cone heel row teeth having crests that are a distance from the bearing pin axis greater than an outer diameter of the disk.   
     
     
         40 . The bit according to  claim 39 , wherein a circumferential distance between adjacent ones of the slots is greater at an edge of the disk than at a base of the slots. 
     
     
         41 . The bit according to  claim 39 , wherein each of the slots has opposed sides that are generally parallel with each other. 
     
     
         42 . The bit according to  claim 39 , wherein the heel row teeth of the second cone are pyramidal in shape. 
     
     
         43 . The bit according to  claim 39 , wherein the heel row teeth of the third cone have crests that are elongated and have lengths perpendicular to a direction of rotation of the cone.