| 摘要 |
A hexahedral-shaped cutting insert has a concavely curved upper surface, a lower surface, a plurality of side surfaces connecting the two, and a central hole passing through the upper and lower surfaces. Cutting edges are formed at intersections between the upper surface and the side surfaces, and corner cutting edge portions are formed at borders of two adjacent cutting edges. Cutting edge height is largest at corner cutting edge portions and smallest in the middle portions. In an inward direction of the insert from a cutting edge, the upper surface has a land portion, a downward inclined surface, a bottom surface, and a seating surface portion. A plurality of semispherical protrusions are formed on border portions between the downward inclined surface and the bottom surface, and at least one corner cutting edge portion has a corner bottom surface surrounded by an outwardly facing arcuate protrusion connecting two adjacent semispherical protrusions. |
