Roller tooth bit with heel row cutter inserts.

摘要

A milled tooth rotary cone rock bit, as it is operated in a borehole, brings the heel of each cone into contact with the borehole wall when the gage row milled teeth wear. The heel row of each cone is relieved and tungsten carbide chisel inserts (134) are equidistantly placed within the relieved heel recess. The heel row inserts cooperate with the gage row milled teeth (129) and progressively cut more of the gage of the borehole as the row of milled teeth on the gage of the cone wear. Moreover, the gage row milled teeth are partially hardfaced leaving relieved areas on the cutting side of each tooth to enhance the cutting action of the gage row of each cone. <IMAGE>