CUTTING INSERT AND EXCHANGEABLE-BLADE CUTTING TOOL

摘要

A cutting insert and an indexable insert-type cutting tool includes a cutting edge (6A) formed on each of a pair of side ridge portions of at least one of the side faces, the pair of side ridge portions being a portion intersecting the side face and a pair of polygonal faces (2), wherein an insert main body (1) is formed in the shape of having front-back inversion symmetry which is 180° rotationally symmetrical with respect to a line of symmetry (N) passing through the center of the side faces; a flank face adjacent to the cutting edge (6A) is formed on the side face in the vicinity of each of the pair of polygonal faces (2), when each of the pair of polygonal faces (2) is used as a rake face; each of the flank faces is formed in the shape of a twisted face in which a flank angle with respect to the cutting edge (6A) gradually increases in a positive angle side while each of the flank faces becoming close to a second corner portion (B) from a first corner portion (A), the first corner portion and the second corner portion being alternately located in a circumferential direction of the pair of polygonal faces (2) at a side ridge portion where the cutting edge (6A) is formed; the pair of side ridge portions on which the cutting edge (6A) is formed intersect each other in such a manner that the second corner portion (B) of one side ridge portion protrudes outside the other side ridge portion when the polygonal face (2) is viewed from the front thereof.