| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent cracks on impact of thermal damage and swarfs during heat-proof alloy cutting.SOLUTION: Front and back polygonal faces 2 have a rake face on one side and a seating face on the other side, and a main cutting edge 5B of a cutting blade 5 comprises: a first region L with a constant rake angle; a second region M with the rake angle getting smaller; and a third region N with a constant rake angle smaller than in the first region L in the order from one end of a corner edge 5A, where the polygonal faces 2 have a protrusion 11 and projections 12 formed with spaces from the cutting blade 5 to make the protrusion 11 project from the cutting blade 5 and comprise a top face 11A perpendicular to the insert thickness direction and a peripheral surface 11B that slopes toward the inside of the polygonal faces 2 according as it directs to the top face 11A to have a projective end 11C facing the corner edge 5A in a plan view, so that the projection 12 keeps the surface convex-shaped with a projection height lower than the protrusion 11 and higher than the main cutting edge 5B and positioned on the opposite side of the corner edge 5A with respect to the projective end 11C, and at least a part of the projection 12 positioned inside of the second region M.</p> |
