ROTARY DRILL BIT WITH CUTTING INSERT FOR ENGAGING EARTH STRATA

摘要

#$%^&*AU2014201702B220170706.pdf#####ABSTRACT OF THE DISCLOSURE A rotary drill bit for engaging an earth strata material includes a cutting insert attached to an axial forward end of an elongate drill bit body. The cutting insert includes an elongate insert body rotatable about a central axis with a pair of symmetrical halves symmetrical about the central axis, each symmetrical half comprising: a leading face; a top surface having a primary relief surface; a web thinning gash extending between the leading face and the primary relief surface, the web thinning gash having a debris evacuation portion centrally disposed adjacent the central axis and a distal transition portion disposed adjacent the debris evacuation portion; a first leading cutting edge at the intersection of the leading face and the primary relief surface; and a second leading cutting edge at the intersection of the web thinning gash and the primary relief surface of the top surface.1/7 IA 150 50 2 3 4 54 44 A 1 1810 2012 FIG. 1 A16 | A