CUTTING-SHEARING DRILLING BIT Russian patent published in 2002 - IPC

FIELD: rock-cutting tools of cutting-shearing action; applicable, mainly, in drilling of blast holes in rocks of opencasts and in drilling of deep holes. SUBSTANCE: cutting-shearing drilling bit has a body and ribs, axles secured in ribs, rock-cutting discs installed on axles eccentrically relative to rotation axes with the help of eccentric bushings. Plane of cutting faces of rock-cutting discs is located at an angle to the body diametrical plane. Drilling bit has pairs of rock-cutting discs. One pair is installed on axles whose one end is secured in legs and its other end in ribs at an angle to diametrical plane of the body with inclination towards drilling bit rotation axis. The other pair of rock-cutting discs is installed on axles secured in parallel ribs of body central diametrical plane. Discs installed in legs are large than those installed in ribs by a factor of 1.5-2. Said drilling bit allows extension of rational application of drilling bits with disc rolling cutters in drilling of hard rocks by varying position of rock-cutting discs relative to the body at which combined cutting-shearing action on rock is provided with elements of crushing action in periphery zone (most difficult to cut from mass) of hole bottom. EFFECT: simplified design, reduced cost as compared with cutting drilling bits, higher efficiency of application of cutting-shearing drilling bits. 2 cl, 2 dwg