| 摘要 |
PROBLEM TO BE SOLVED: To reduce chipping of an R-part of a tip blade by eliminating chatter with respect to a member having high strength and difficult-to-cut property, and reducing the resistance of a member to be cut against a cutting blade while keeping cutting performance high. SOLUTION: A tool body 12 includes a plurality of the tip blades 16 arranged in the radial direction from a center on a ball-shaped tip part and a plurality of side blades 18 continued to the tip blades. Elliptically continuous irregularities are formed in such a manner that the tip blades 16 and side blades 18 as the irregularities have the long axes of cross-section elliptical-contour-lines of the irregularities directed toward an axis line A of the tool body, the differences H<SB POS="POST">1</SB>between the crests and valleys in the irregularities 22 of the tip blades 16 are 0.1-0.15 mm, pitches P<SB POS="POST">1</SB>of the tip blades are 0.8-1.0 mm, the differences H<SB POS="POST">2</SB>between the crests and valleys in the side blades 18 are 0.3-0.5 mm, pitches P<SB POS="POST">2</SB>are formed to be 1.2-1.5 mm, and helical angles α of helical flutes 20 with respect to the axis line A are formed to be 15-30°. COPYRIGHT: (C)2012,JPO&INPIT
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