Means for mounting a roller cutter on a drill bit.

摘要

A rotary drill bit (10) having a roller cutter (28) retained on a journal (24) by an externally threaded retainer ring (52) mounted within an annular groove (48) in the journal (24). The radii (R1, R2) formed at the inner and outer corners of the groove (48) are designed by suitable formulas to provide adequate strength for the journal (24) including the flange (50) adjacent the groove (48).