DRILL Russian patent published in 2006 - IPC B28D1/14 B23B51/00 

FIELD: mechanical engineering.

SUBSTANCE: drill comprises main cutting blades provided with the main cutting edges whose shape provides its inner end to be located at the center of rotation of the drill. The external end of the cutting edge is located at the circumference described by the periphery of the cutting blades when they rotate. The auxiliary cutting blades have the auxiliary cutting edges whose shape allows the inner end of the cutting blade to be at a distance from the center of rotation in the radial direction. The outer end of the auxiliary cutting blade is located at a distance from the circumference toward the center of rotation. The grinding surface is interposed between the auxiliary cutting edge and the center of rotation. The surface is located at a distance from the auxiliary cutting edge in the inward direction and is inclined to the back side of the auxiliary cutting blade.

EFFECT: enhanced efficiency of drilling.

9 cl, 4 dwg