CUTTING INSERT, TOOL BODY ON WHICH SAID CUTTING INSERT MAY BE MOUNTED, AND REPLACEABLE-BLADE-TYPE BALL-END MILL PROVIDED THEREWITH

摘要

Provided is a cutting insert for a replaceable-blade-type ball-end mill in a three-blade configuration compatible with all cutting blades using a single type. The intersecting ridge lines of the top surface (2) and side surfaces (4a, 4b) of a cutting insert (1) have two opposing arcuate primary cutting blades (8, 10), and the intersecting ridge lines of the bottom surface (3) and side surface (4a) have a single arcuate primary cutting blade (9). One (8) of the cutting blades on the top surface and the cutting blade (9) on the bottom surface are on one side surface in relation to the middle line (ML), and the other cutting blade (10) on the top surface is on the other side surface. The length (L1) between the two cutting blades (8, 10) on the top surface is greater than the length (L2) between the cutting blade (9) on the bottom surface and the intersecting ridge line (11). When viewed in a cross section substantially perpendicular to the middle line, the angle (α) formed by the top surface and a straight line (L3) connecting the cutting blade (8) on the top surface on one side surface (4a) and the cutting blade (9) on the bottom surface is different from the angle (β) formed by the top surface and a straight line (L4) connecting the cutting blade (10) on the top surface on the other side surface (4b) and the intersecting ridge line (11) on the bottom surface.