CUTTING INSERT AND EXCHANGEABLE-BLADE CUTTING TOOL

摘要

This cutting insert and exchangeable-blade cutting tool have a front-back inversion symmetrical insert main body (1) such that a cutting edge (6A) is formed at each of a pair of side edges intersecting a pair of polygonal surfaces (2) at at least one side surface, and that is 180° rotationally symmetrical with respect to a line of symmetry (N) passing through the center of the side surface. At the side surface, the flanks of the cutting edge (6A) when the pair of polygonal surfaces (2) are each cutting faces are formed at the sides towards the pair of polygonal surfaces (2). At the side edges to which the cutting edge (6A) is formed, the flanks are formed in a twisted surface shape resulting from the flanks with respect to the cutting edge (6A) gradually becoming larger to the positive angle side from one corner section (A) to another corner section (B) that alternate in the circumferential direction of the pair of polygonal surfaces (2). When the pair of side edges to which the cutting edge (6A) is formed are seen from a direction facing the polygonal surfaces (2), the other corner section (B) of one side edge is mutually intersecting in a manner so as to protrude to the outside of the other side edge.