Abstract: A mounting seat bottom surface facing a holder rotation direction; a first mounting seat wall surface (3b) facing an outer peripheral side of the holder main body (1), and a first relief portion (3d) on a corner portion where they intersect, are formed on an outer peripheral portion of a tip of a holder main body (1) rotated in a direction around an axis, on the inner peripheral side of the first mounting seat wall surface (3b), an inclined face (6) is formed in a range from an end edge (3b1) of the first mounting seat wall surface (3b) to 2 mm or less in the inner peripheral side, and the inclined face (6) being retracted toward the posterior end side in the axial direction as being extended toward the inner peripheral side, and an inclination angle ? is 20° or more and 50° or less.

Abstract: A cutting insert includes a rake face configuring one of polygonal surfaces, a seating surface configuring the other one of the polygonal surfaces, and a side surface connecting the rake face and the seating surface to each other. The cutting insert has a cutting edge portion including a main cutting edge located in a side portion of the rake face, a subsidiary cutting edge connected to the main cutting edge, and a corner cutting edge connected to the subsidiary cutting edge and located in a corner portion of the rake face. The side surface includes a flank face and a connection surface which are adjacent to each other in a thickness direction via a boundary line. The connection surface is located on the seating surface side, and is located outside than an extension line of the flank face.

Abstract: A detachable cutting insert for an indexable rotary cutting tool, has a cutting edge portion that includes a major cutting edge continuous with a first end of a first corner edge near a short-side-direction side surface, which is formed into a straight line. The cutting insert has a first minor cutting edge that is continuous with a second end of the major cutting edge, which is formed into a circular arc. The cutting insert has a second minor cutting edge that is continuous with a third end of the first minor cutting edge, which is formed into a straight line. In a cross-sectional view of a rake face of the second minor cutting edge, perpendicular to the second minor cutting edge, a cross-sectional ridgeline of the rake face of the second minor cutting edge is formed into a convex shape protruding above a cross-sectional ridgeline of a reference plane.

Abstract: A cutting insert includes a rake face configuring one of polygonal surfaces, a seating surface configuring the other one of the polygonal surfaces, and a side surface connecting the rake face and the seating surface to each other. The cutting insert has a cutting edge portion including a main cutting edge located in a side portion of the rake face, a subsidiary cutting edge connected to the main cutting edge, and a corner cutting edge connected to the subsidiary cutting edge and located in a corner portion of the rake face. The side surface includes a flank face and a connection surface which are adjacent to each other in a thickness direction via a boundary line. The connection surface is located on the seating surface side, and is located outside than an extension line of the flank face.

Abstract: In the cutting insert of the present invention, the cutting edge portion includes: a first corner edge; a major cutting edge continuous with a first end portion (S1) of the first corner edge near the short-side-direction side surface and formed into a straight line; a first minor cutting edge continuous with a second end portion (S2) of the major cutting edge and formed into a circular arc; and a second minor cutting edge continuous with a third end portion (S3) of the first minor cutting edge and formed into a straight line. In a cross-sectional view of a rake face of the second minor cutting edge perpendicular to the second minor cutting edge, a cross-sectional ridgeline of the rake face of the second minor cutting edge is formed into a convex shape protruding above a cross-sectional ridgeline of a reference plane.