| 摘要 |
PROBLEM TO BE SOLVED: To divide chips excellently at the time of low depth of cut and a low feed rate, by forming a pair of hollows on a nose part of a throwaway tip, symmetrically relative to a bisector for roughly bisecting the nose part. SOLUTION: Hollows 16 are formed on the further outside of a tip than projections 13. The hollows 16 are a pair of hollows having elliptic shapes, and are positioned symmetrically relative to a straight line for roughly bisecting a nose part 7, and the distance between two major axes of the elliptic shapes increases as they separate from the nose head, and the elliptic arc of an opening part is arranged nearly along the boundary between a land part 9 of the nose part 7 and an inclined part 10. In the region of low depth of cut, chips produced at the nose part 7 are deformed immediately by the hollows 16. The hollows 16 lead the flow of the chips to a lower position of the inclined part 10, and makes it collide surely with the projections 13, to thereby enlarge the deformation. Hereby, the chips are divided excellently.
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