DRILLING BIT Russian patent published in 1997 - IPC

FIELD: mining engineering. SUBSTANCE: invention is applicable in drilling bits for drilling holes with air and gas, in expanders, and in other drilling tools. Drilling bit contains casing with nipple and blow channels wherein, by the aid of stop and sealing means, valve units are installed consisting of protective shell, locking member of any shape (e.g. spherical), and return spring with rod. The two latter are protected against slurry particles by protective case with cellular bottom-screen. Protective case, in its upper part, has sealing and stopping members providing easily and quickly replacing entire unit by another with required open flow area. EFFECT: improved design. 3 cl, 2 dwg