Cutting insert
A cutting insert capable of performing groove machining while efficiently fragmenting chip is provided. A cutting insert 10 includes a front cutting edge 111 , a pair of side cutting edges 113 , a pair of corner cutting edges 112 each connecting the front cutting edge and a corresponding one of the side cutting edges, corner rake surfaces 122 extending from the corner cutting edges 112 , and a protrusion part 150 protruding from the corner rake surfaces 122 and provided with a flat boss surface 160 at a leading end. Corner wall surfaces 180 extending from the boss surface 160 toward the corner rake surfaces 122 are formed at the protrusion part 150 . At least a part of the corner wall surfaces 180 has a tilt angle of 40° or larger relative to the boss surface 160.
1 . A cutting insert used for groove machining, the cutting insert comprising:
a front cutting edge;
a pair of side cutting edges;
a pair of corner cutting edges each connecting the front cutting edge and a corresponding one of the side cutting edges;
corner rake surfaces extending from the corner cutting edges; and
a protrusion part protruding from the corner rake surfaces and provided with a flat boss surface at a leading end, wherein
an entirety of the boss surface is flat,
corner wall surfaces extending from the boss surface toward the corner rake surfaces are disposed at the protrusion part,
at least a part of the corner wall surfaces has a tilt angle of 40° or larger relative to the boss surface,
the corner wall surfaces each includes a first corner wall surface and a second corner wall surface, the first corner wall surface being a part on the boss surface side, the second corner wall surface being a part on the corner rake surface side,
a tilt angle of the second corner wall surface relative to the boss surface is smaller than a tilt angle of the first corner wall surface relative to the boss surface, and
an entirety of the first corner wall surface continuously extends away from the corner rake surface and toward a plane which includes the flat boss surface.
2 . The cutting insert according to claim 1 ,
wherein, when viewed in a direction perpendicular to the boss surface,
at least one of the first corner wall surface and the second corner wall surface protrudes in a circular arc shape toward the corner cutting edges.
3 . The cutting insert according to claim 1 ,
wherein a first part being provided with the front cutting edge, the side cutting edges, the corner cutting edges, the corner rake surfaces, and the protrusion part, and
a second part being held by a holder of a cutting tool are joined to each other.
4 . The cutting insert according to claim 3 , wherein the first part is formed of a material containing cubic boron nitride.
5 . The cutting insert according to claim 1 , wherein an entirety of the second corner wall surface continuously inclines away from the corner rake surface towards the first corner wall surface and the plane which includes the flat boss surface.
6 . The cutting insert of claim 1 , wherein an entirety of the second corner wall surface is between the corner cutting edge and the flat boss surface.