DRILL BIT FOR PERCUSSION-ROTARY DRILLING Russian patent published in 1997 - IPC

FIELD: well drilling. SUBSTANCE: drill bit has a case made in the form of a tail and head with through central hole. Upper portion of the hole is of truncated cone shape. Large base of the cone is placed on head face. Cylindrical insertion pieces of hard alloy are placed over periphery of the head. Head diameter is 3 - 4 times as large as that of insertion piece diameter. Large base radius of the cone corresponds to the distance from drill bit axis to the insertion pieces. Angle of the conical opening apex is within 45 to 90 degrees. EFFECT: higher efficiency of the drilling. 4 dwg, 1 tbl