| 摘要 |
PROBLEM TO BE SOLVED: To reduce lowering of sharpness while securing the cutting edge strength of a throwaway tip. SOLUTION: This tip 1 is substantially square plate-like, and two pairs of cutting edges non-parallel to the top face are taken as first and second short cutting edges 6, 7 and first and second long cutting edges 8, 9. The corner angle of two corner cutting edges 10 clamping the first short cutting edge 6 is 90 deg. or smaller, the other corner cutting edge 11 is 90 deg. or smaller, and the corner cutting edge 13 is an obtuse angle. A part rather close to the fourth corner cutting edge 13 of the first long cutting edge 8, and a part rather closer to the second corner cutting edge 11 of the second long cutting edge 9 are provided with reinforcing parts 15. One of two same tips projecting toward the tip of the tool body 21 takes the second long cutting edge 9 as a front cutting edge, and takes the first short cutting edge 6 as an outer peripheral cutting edge, and the reinforcing part 15 of the second long cutting edge 9 is positioned on the inner peripheral side of the tool. The other takes the first short cutting edge 6 as a front cutting edge, and takes the first long cutting edge 8 as an outer peripheral cutting edge, and the reinforcing part 15 of the first long cutting edge 8 is positioned on the tool base end side.
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