A TWO-PRONG ROTARY BIT,ESPECIALLY FOR USE WITH ROOF DRILLS,AND INSERT THEREFOR

摘要

A two-prong rotary drill bit, especially for use with mine roof drills comprises a supporting body 14 defining prong portions with an insert on each prong. Each of the inserts has a cutting portion facing in the direction of rotation formed with two planar faces 26 converging towards the cutting direction whereby when viewed in a direction parallel to the axis of rotation, each will have a cross sectional configuration which is generally wedge-shaped.