DRILL BIT Russian patent published in 2001 - IPC

FIELD: drill bit applicable in compressed air drilling. SUBSTANCE: drill bit comprises body with air courses for hole bottom cleaning and cooling of cone bearings and check valves installed in hollows bored in body perpendicular to air courses. Check valves are made in the form of spring-loaded pistons with retainers and guide. Piston is cylindrical in shape with bevelled end oriented with its top towards its lower part and held in such position by guide formed by longitudinal recess on piston side surface and rod installed in recess and secured in drill bit body. Value of axial motion of piston is limited by retainer installed coaxially to piston for interaction of its internal end face with protrusion of piston bevelled end. Retainer has flexible spacer secured on side of air course. Piston diameter on side of air course of end face is equal to or larger than diameter of air course in zone of their conjugation. EFFECT: increased footage per bit and rate of penetration. 3 cl, 2 dwg