Rotary-percussion drill bit with heel row inserts to prevent wedging

Claim 1

IN A ROTARY-PERCUSSION BIT COMPRISING A BIT BODY HAVING A GENERALLY FLAT BOTTOM SURFACE AND A GENERALLY CYLINDRICAL GAGE SURFACE RELIEVED BY LONGITUDINAL GROOVES, A MULTIPLICITY OF WEAR RESISTANT INSERTS SECURED IN SAID BODY WITH CUTTING TIPS PROTRUDING FROM SAID BOTTOM SURFACE AND SPACED APART IN CIRCUMFERENTIAL ROWS, AND A FLUSHING FLUID PASSAGEWAY SYSTEM WHICH INCLUDES INTERCONNECTED INTERNAL PASSAGES EXTENDING LONGITUDINALLY FROM THE TOP TO THE BOTTOM OF THE BIT BODY, THE IMPROVEMENT COMPRISING DISPOSING THE INSERTS OF THE OUTERMOST OF SAID CIRCUMFERENTIAL ROWS AT AN ACUTE ANGLE WITH RESPECT TO THE LONGITUDINAL AXIS OF THE BIT SO THAT THE INNER ENDS OF SUCH INSERTS ARE BURIED WITHIN THE BODY IN SPACED RELATION FROM BOTH THE BOTTOM AND GAGE SURFACES AND THE CUTTING TIPS EXTEND BEYOND BOTH SAID SURFACES AT ABOUT THE INTERSECTION THEREOF.