CUTTING INSERT, TIP EXCHANGING TYPE BALL END MILL, END MILL BODY OF TIP EXCHANGING TYPE BALL END MILL

摘要

To reliably prevent displacement movement at a cutting time without damaging a strength of a cutting insert.SOLUTION: A cutting insert 1 comprises: a rake face; a seating surface 3 which is directed to a side opposite to the rake face, and is seated on an insert attachment seat; and a flank 4 which extends around the rake face and the seating surface 3. Two cutting blades 5, 6, which comprise circular arc-shaped cutting edge parts 5a, 6a which extend in a circular arc-shape, and linear cutting edge parts 5b, 6b which contact the circular arc-shaped cutting edge parts 5a, 6a, are formed at an intersection ridge line part between the rake face and the flank 4. A groove part 8 having a wall surface 8b, which can contact a protrusion which projects from a bottom surface of the insert attachment seat, is formed on the seating surface 3, and the groove part 8 has a width narrow part 9 in which a groove width becomes gradually narrow as going from one end side toward the other end side in an extension direction of said groove part 8.SELECTED DRAWING: Figure 3