| 摘要 |
PROBLEM TO BE SOLVED: To provide a cutting insert having a flat plate-like insert body of which the four sides can be used as cutting edges, and in which the cutting edges are polishable.SOLUTION: A cutting insert 20 includes a flat plate-like insert body 21. The insert body 21 has four cutting edges 22a to 22d. The shape of the cutting blades 22a to 22d when seen from a normal direction of lateral surfaces 21c and 21d of the insert body 21, forms an involute curved line expanding outside with respect to the insert body 21. The insert body 21 has flanks 23a to 23d. A cross-sectional shape along a lateral surface 21c of the flanks 23a and 23b is the same as the shape of the cutting edges 22a and 22b. A cross-sectional shape along the lateral surface 21d of the flanks 23c and 23d is the same as the shape of the cutting edges 22c and 22d. The insert body 21 further has a flat surface 25a provided on a top face 21a, and a flat surface 25b provided on a lower surface 21b. |
