Cutting insert

Abstract

In a cutting insert, a cutting edge is formed on a peripheral border of a rake face; a protruding section is formed on the rake face; a pair of convex sections is formed so as to extend toward the cutting edge; the convex sections face toward a corner portion; the convex sections include first wall surfaces and second wall surfaces; the first wall surfaces and the second wall surfaces are inclined surfaces that are inclined toward the rake face as those are farther from ridgelines intersecting with each other; and the intersection ridgelines intersect with a wall surface of the protruding section, at a position lower than a top portion of the protruding section in the corner portion side.

1 . A cutting insert, wherein:
 a cutting edge having a corner portion is formed on a peripheral border of a rake face of an insert body;   a protruding section is formed on the rake face inside the corner portion so as to protrude at a distance away from the cutting edge;   a pair of convex sections is formed on both sides of the corner portion divided by a bisector in the range from a wall surface of the protruding section to the rake face so as to extend toward the cutting edge;   the convex sections face toward the corner portion of the cutting edge;   the convex sections include first wall surfaces that more separated from each other to extend toward both ends of the corner portion, respectively, as the first wall surfaces are farther from the wall surface of the protruding section and closer to the cutting edge, and second wall surfaces that extend toward the cutting edge adjoined to the both ends of the corner portion by intersecting with the first wall surfaces;   the first wall surfaces and the second wall surfaces are inclined surfaces that are inclined toward the rake face as those are farther from ridgelines intersecting with each other; and   the intersection ridgelines intersect with the wall surface of the protruding section, at a position lower than a top portion of the protruding section in the corner portion side.   
   
   
       2 . The cutting insert according to  claim 1 , wherein
 a tilt angle of the second wall surfaces in a cross section orthogonal to the cutting edge adjoined to the both ends of the corner portion is smaller than a tilt angle of the first wall surfaces in the cross section orthogonal to the intersection ridgelines.   
   
   
       3 . The cutting insert according to  claim 1 , wherein
 the second wall surfaces are formed as a convex curve surface curved toward the rake face.   
   
   
       4 . The cutting insert according to  claim 1 , wherein
 the wall surface of the protruding section facing to the corner portion between the first wall surfaces of the pair of convex sections is formed as a convex curve surface curved along the corner portion.   
   
   
       5 . The cutting insert according to  claim 1 , wherein
 a rib section having a lower protrusion height than the convex section and a narrower width than a distance between the first wall surfaces is formed along the bisector between the first wall surfaces of the pair of convex sections on the rake face inside the corner portion.   
   
   
       6 . The cutting insert according to  claim 5 , wherein:
 the protrusion height of the top portion in the protruding section is a higher planar surface than the cutting edge in the corner portion;   the wall surface of the protruding section is an inclined surface that is gradually uplifted toward the top portion as it gets closer to the inside of the corner portion;   the rake face inside the corner portion includes a positive rake face that is gradually recessed as it gets closer to the inside of the corner portion; and   a protruding ridge portion of the rib section is formed at a distance away from the cutting edge and extends so as to be parallel to the top portion, be gradually uplifted with a lower inclination than the wall surface of the protruding section, or be gradually recessed with a lower inclination than the positive rake face, toward the inside of the corner portion from the positive rake face that is a position closer to the cutting edge than the convex section in a direction of the bisector.   
   
   
       7 . The cutting insert according to  claim 5 , wherein:
 the protruding section is a planar surface in which the protrusion height of the top portion is higher than the cutting edge in the corner portion;   the wall surface of the protruding section is an inclined surface that is gradually uplifted toward the top portion as it gets closer to the inside of the corner portion;   the rake face inside the corner portion includes a positive rake face that is gradually recessed as it gets closer to the inside of the corner portion and a flat rake face inside the positive rake face; and   a protruding ridge portion of the rib section is formed at a distance away from the cutting edge and extends so as to be gradually uplifted with a lower inclination than the wall surface of the protruding section toward the inside of the corner portion from the flat rake face.