DRILL INSERT AND THROWAWAY DRILL USING IT

摘要

PROBLEM TO BE SOLVED: To improve discharging performance of chips without any sacrifice in cutting performance, in a throwaway drill to be used for punching a small- diameter hole. ;SOLUTION: In a throwaway drill 10, a drill insert provided with an inner cutting edge 2 and an outer cutting edge 3 is mounted by a fixing bolt 13. A pocket 14 for discharging large chips is secured on the upper part (on the rotational direction side) of a cutting face 4 of the inner cutting edge 2 by deviating the position of the central axis of the fixing bolt 13 from the position of the central axis of the holder 11 in the direction of the outer cutting edge 3.;COPYRIGHT: (C)1999,JPO