BORING BIT FOR ROTARY DRILLING Russian patent published in 1997 - IPC

FIELD: boring bits applicable in drilling boreholes in coal and rocks with hardness f equalling up to 8 to Protodyakonov scale. SUBSTANCE: boring bit for rotary drilling has body with shank, two wings and hard metal inserts. Each insert has main blade edge in form of asymmetric broken line with point of bend in the wing cop, rear face parallel to diametric plane and blade face with recess having inclined walls which form obtuse angle and rib located on the rear side of each wing from its top to the plane of contact of body with spiral drill rod. Contact plane is located perpendicular to axis of rotation of boring bit, its body and drill rod. Below the contact plane boring bit has strengthening-and-connecting plane-curved minishank located between the body and shank. EFFECT: higher efficiency. 4 cl, 3 dwg ЫЫЫ1