DRILLING BIT Russian patent published in 2006 - IPC E21B10/02 E21B10/48 

FIELD: rock drilling equipment, particularly core bits adapted to drill fractured rock and rock having variable hardness.

SUBSTANCE: drilling bit comprises body with slits formed in lower part thereof. The slits are inclined in direction opposite to body rotation direction and divide the body into sectors reinforced with concentrically arranged cutters. The drilling bit also has guiding bush with connection thread arranged in body interior. The sectors are arranged in steps and the leading sectors are reinforced with rock-cutting members having lesser wear resistance and lesser bending resistance in comparison with other drilling bit sectors. To provide this the leading sectors have reduced cross-sections. The cross-sections are reduced by forming unloading radial channels arranged at slit bases or by imparting trapezoid shapes to the leading sectors, wherein the bases of trapezoid sectors are arranged from connection thread side.

EFFECT: increased efficiency of rock cutting due to stepped face creation, possibility to cut rock of different hardness with cuts having different wear resistance.

5 cl, 3 dwg