DRILLING BIT Russian patent published in 1999 - IPC

FIELD: bore-hole drilling equipment. SUBSTANCE: relates to percussive-rotary drilling machinery and actually to drilling tools intended for operation with immersed pneumatic hammer which can be used for driving bore-holes in hard rock matter. Drilling bit has head-piece fortified with hard-alloy inserts, and cylindrical tail-piece with central exhaust passage, longitudinal recesses and longitudinal teeth in its side surface having outcome to end face of tail-piece and made in the form of straight-side spline cutting. Recess is made in tail-piece which is coaxial with generant of side surface. External diameter of this recess is larger than or equal to diameter of tail-piece over longitudinal recesses. Aforesaid embodiment of drilling bit is simplified in design and is of higher strength. EFFECT: higher efficiency. 1 cl, 6 dwg