CROWN BIT FOR DRILLING WITH PERFORATOR Russian patent published in 1996 - IPC

FIELD: drilling tools; hard-alloy insert rolling-cutter bits for rotary pneumatic (percussive-rotary) drilling; applicable in drilling and blasting operations. SUBSTANCE: crown bit for drilling with perforator has body consisting of head with conical side surface, shank and cylindrical-and-spherical inserts installed at angle to crown axis and located on end face of head over its periphery. Peripheral side surface of cylindrical-and-spherical inserts has area which is essentially spreading the side conical surface of the head. In this case, radius drawn from the center of Spherical surface of each insert of point of intersection of conical and spherical surfaces of insert located in radial section of crown forms with plane perpendicular to crown axis the angle of 30-45 deg. In so doing inserts are to be installed at angle of 10-20 deg to crown axis. EFFECT: higher serviceability of drilling tool due to reduced breakage of hard-alloy inserts and reduced intensity of their wear over periphery. 6 dwg, 1 tbl