ROLLER BIT

FIELD: rock breaking tools. SUBSTANCE: roller bit includes arms making body of bit, rolling cutters mounted in bearing assemblies and nozzle with cone internal hydraulic conduit located in central hole of body. Six longitudinal slits are made in wall of nozzle. Three equal slits with larger areas of outlet sections which expand along length from center to periphery of roller bit are arranged uniformly and are strictly directed into spaces between rolling cutters and three equal slot-shaped slits with smaller areas of outlet sections have identical width and are directed with inclination to surfaces of rolling cutters and their axes in plan are displaced with reference to axes of rolling cutters in direction of rotation of bit through angle alpha = 15/25°. Summary areas of outlet sections of larger and smaller slits are interrelated by following relationship SigmaFl.a/SigmaFs.a = (2,0/3,5), where SigmaFl.a and SigmaFs.a are summary areas of outlet sections of correspondingly larger and smaller slits, sq mm. EFFECT: coverage with jet action of entire surface of face, improved cleaning of rolling cutters from driven rock, counteraction to balling at bit, rational distribution of flows of flushing fluid, increased technical and economic indices of drilling and raised operational reliability of roller bit. 2 dwg