DRILL Russian patent published in 2013 - IPC B23B51/02 B28D1/14 E21B10/42 

FIELD: process engineering.

SUBSTANCE: invention relates to machine building and may be used in drills for drilling concrete or other stone structures, rocks, etc. Said drill comprises shank with clamping lug and drilling head arranged at the end opposite said clamping lug. Said head comprises, at least, three, preferably three blades, shaped to wings in top view. Every blade comprises cutting rib at top side formed by lead chipping edge and rear side. Cutting ribs converged in central zone with center at drill axis. One long cutting rib extends in said central zone through drill axis and comprises proportionate transitional section extending beyond drill axis. Long cutting ring makes drill blade about drill axis that comprises two radially outer ends extending axially from drill blade so that rear side of one cutting rib and that of another cutting rib make flute-like recess in central zone while long cutting rib cross said recess.

EFFECT: higher drilling speed, longer life.

26 cl, 16 dwg