| 摘要 |
PROBLEM TO BE SOLVED: To provide a throw-away tip particularly suited for cutting of stainless steels by providing a breaker groove with a low cutting resistance and an improved cutting edge strength. SOLUTION: A cross section shape of a breaker groove 8 is constituted from a cutting edge to a center part in the order of, lands 9 (rake angleθ1) each having positive rake angles, a first inclined plane 10 (rake angleθ2), a second inclined plane 11 (rake angleθ3), and a an erected surface 12, and a relationship thereof isθ2>θ1>=θ3>0. Also, a projection 7 extending from the center part is formed on the corner. Furthermore, the rake anglesθ1 of the lands 9 are formed larger at the corner and smaller at a center part of a main cutting edge 2, and widths w of the lands 9 are formed narrower at the corner and wider at the center part of the main cutting edge 2.
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