| 摘要 |
Since a bottom diameter d of a plurality of helix flutes 16 is increased from a tool tip toward a shank 12, breakage strength is improved and high-load or high-efficiency processing with deep cutting dimensions is enabled along with a longer tool life while higher tool rigidity suppresses flexural deformation, thereby further improving machining accuracy. Lands 18 of peripheral cutting edges 20 consist only of peripheral relieving portions and therefore increase flute width dimensions of the helix flutes 16 between the lands 18, i.e., width dimensions of chip pockets so that the chip pockets with a sufficient size can be ensured regardless of the increase in the flute bottom diameter d, and a slope can be disposed on a flute bottom while suppressing clogging of chips, thereby improving the breakage strength. |
