| 摘要 |
Since a pair of first spiral flute 24 and second spiral flute 26 disposed in a drill main body 12 of an indexable drill 10 is subjected to a hardening heat treatment and then mirror-finished through cutting by ball end mills 30 and 32, friction of flute inner surfaces is reduced and chips are favorably discharged. This suppresses wear, blade chipping, breakage etc., due to clogging of chips and improves durability (tool life) even in a deep hole machining indexable drill 10 having longer flute length L. An increase in cutting resistance due to clogging of chips is suppressed so that stable hole machining can be performed, and limiting machining conditions for enabling the hole machining are alleviated so that a machinable range is expanded. |
