ROLLER BIT FOR DRILLING HOLES WITH BLOWING BY COMPRESSED AIR Russian patent published in 1997 - IPC

FIELD: mining industry. SUBSTANCE: roller cutting bit has body with nipple and blowing passages, lugs with cutters attached to body, nozzles installed in blowing passages, and located in them is sludge-protection locking member. This member has cone of elastic-resilient material with annular protrusion. Installed in inner space of cone is framework made in the form of truncated cone with open ends and openings in side surface. Framework is installed so that its flange rests on bit body shoulder. Cone is provided with non-return valve made in the form of flat hose with slot located beyond outlet hole of nozzle. Nozzle is secured to bit body by axial detent. Annular protrusion is located between bit body shoulder and upper end of nozzle. Distance L from axis of axial detent to body shoulder is correlated with distance l from detent axis to nozzle upper end and height h of annular protrusion by following expression: L <l + h. Inner surface of nozzle can be of permanent or varying cross section, with reduction of cross-section towards nozzle outlet hole. Bit of this design with sludge-protection member reliably protects inner space of bit in drilling dry and flooded wells. EFFECT: high efficiency. 1 cl, 3 dwg