DRILLING BIT Russian patent published in 2006 - IPC E21B10/36 

FIELD: well drilling equipment, particularly percussion drill bits adapted to drill in fractured ground.

SUBSTANCE: drilling bit comprises body with cleaning channels, connection liner and working head with diametrical groove for hard-alloy inserts receiving. The drilling bit is also provided with limiter made as at least one hollow removable bush installed in the cleaning channel so that hollow removable bush position may be adjusted relative working drilling bit end. The removable bush has drive made as screw pair and providing axial bush movement. The drive is arranged in body interior.

EFFECT: increased advancing speed due to hard-alloy insert chippage prevention.

5 cl, 2 dwg