ROCK-CUTTING HARD-ALLOY INSERT FOR CONE DRILL BITS Russian patent published in 1997 - IPC

FIELD: rock-cutting tools, in particular, cone drill bits. SUBSTANCE: working head of insert is formed by crossing of hemispherical surface and two secant planes forming angle in excess of 130 deg. Located on the top of working head between secant planes is boss. Radius R of curvature of boss generating line, radius $$$ of generating line of hemispherical surface and radius r of curvature of generating line of boss in cross-section square to its length are related to each other as R $$$ r. Height h of working head is related to boss length and diameter d of insert cylindrical base as follows d $$$ 1.5L $$$ 2h. The given design of insert allows creation of high stress concentration in rock with preservation of more low level of stress-deformed state of insert material. EFFECT: higher efficiency. 4 dwg