ROTARY DRILLING BIT WITH CALIBRATING PLATFORMS, WHICH HAS INCREASED CONTROLLABILITY AND REDUCED WEAR Russian patent published in 2012 - IPC E21B10/26 

FIELD: mining.

SUBSTANCE: rotary drilling bit includes housing, rotation axis, blades; at least one of the blades has calibrating platform with external surface; external surface has edge located upstream the well shaft and provided with front edge restricted with the first radius and rear edge restricted with the second radius; at that, the above radii are not equal at their measurement in the plane passing perpendicular to the bit rotation axis. As per some designs the bit includes recessed section or cut-out formed in external surface at least of one calibrating section and having reduced radius and general configuration of parallelogram. As per the other designs the bit has two unequal axial conicities on external surface of calibrating section, which are located so that they adjoin the front and rear edges respectively. As per the other design, external surfaces of teeth are located in radial conical configuration passing from the place near front edge of calibrating platform to rear edge of calibrating platform.

EFFECT: improvement of the bit controllability during formation of inclined-directed well shaft without deterioration of transverse stability; reduction of wear of calibrating platform; enhancement of the bit capability of forming the well shaft having in general the constant inner diameter.

44 cl, 12 dwg