BLADE DRILL BIT TO DRILL ROCK HAVING ALTERNATING RIGIDITY Russian patent published in 2008 - IPC E21B10/42 

FIELD: mining, particularly fork-type rotary drill bits, for example fish tail bits with detachable blades.

SUBSTANCE: drill bit comprises body with connection thread and cleaning agent channel, stepped blades installed on the body so that blades define positive front angle with drill bit axis. The blades are reinforced with hard-alloy teeth. End surfaces of all steps are beveled and inclined at 18-22° angles to drill bit rotation direction. Peripheral part of blade has thickened area. End of rear half of thickened area is under end of front half thereof in height direction. Distance between rear and front half ends is equal to half of tooth projection over blade body.

EFFECT: increased service life due to increased average mechanical drilling speed.

3 dwg