DRILL BIT Russian patent published in 1997 - IPC

FIELD: mining industry. SUBSTANCE: drilling of bore-hole preferably with return delivery of core material is performed by drill bit having body and mounted on its working end face are strip-type hole cutting and core-making cutting tools. They are fixed from radial displacement respectively by outer and inner undercutting tools. Inner tolls are located in radial holes of body and are made with stepped tail-piece which interacts with end face of main cutting tools. Main and undercutting tools are installed in horizontal plane at angle to each other. Main cutting tools are positioned at acute angle as to body radius. EFFECT: high efficiency. 2 cl, 3 dwg