CONE DRILL BIT Russian patent published in 2003 - IPC

FIELD: drilling equipment with bubble aeration. SUBSTANCE: cone drill bit has passages in legs to supply air from central hole of nipple to bearing assemblies for their cooling. Air is discharged only partially through clearances between end face of cone and leg and major air current is guided into outlet passages going from base of pilot pin to back of leg outwards, is directed at angle upwards to wall of hole to improve face cleaning from cuttings. They have minimal total area of cross-sections of inlet passages of leg satisfying relation S_cl+ΣS_i≥S_in, where S_i is minimal area of cross-section of i-th outlet passage of leg; S_cl is area of clearance between end face of cone and leg; S_in is total area of inlet passages of leg. Design of cone drill bit with improved air circulation ensures more qualitative cooling of bearing assemblies and more efficient cleaning of face from cuttings which results in increased strength of bearing assembly, speed of drilling and driving. EFFECT: enhanced operational reliability of cone drill bit. 2 dwg