ULTRA HARD INSERT CUTTERS FOR HEEL ROW ROTARY CONE ROCK BIT APPLICATIONS

摘要

ULTRA HARD INSERT CUTTERS FOR HEEL ROW ROTARY CONE ROCK BIT APPLICATIONS A rotary cone rock bit for drilling boreholes in an earthen formation has one or more rotary cones rotatively retained on a journal bearing connected to the rock bit body. These rotary cones have a plurality of tungsten carbide inserts and a gage row of tungsten carbide inserts for drilling the hole diameter. A circumferential heel row has extended ultra hard shaped cutters spaced within the heel row. Each of the shaped cutters has a cutting edge that shears a borehole wall formed by the formation as the rotary cone rotates against a bottom of the borehole formed by the formation. The shaped cutters serve to maintain the borehole diameter and to divert formation debris away from bearing surfaces formed between the rotary cone and the journal bearing. Preferably the ultra hard cutters have a polycrystalline diamond cutting edge.