| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball end mill that has a higher cutting speed, improved machining efficiency and a prolonged tool lifetime while sufficiently securing cutting edge strength and wear resistance of an outer peripheral blade although an end mill body is formed of ceramic.SOLUTION: A ball end mill comprises: an end mill body 2 made of ceramic; an outer peripheral blade 6 formed at a ridge of intersection of a wall face, facing a tool rotating direction T, of a chip discharge groove 4 formed on an outer periphery of the end mill body 2 and an outer peripheral surface of the end mill body 2; a bottom blade formed at a ridge of intersection of the wall face of the chip discharge groove 4 and a tip end face of the end mill body 2, being in a convex arc shape convex to a front end outer peripheral side of the end mill body 2, and smoothly connecting with a tip of the outer peripheral blade 6 to extend from the tip onto an axis O. At least the outer peripheral blade 6 between the outer peripheral blade 6 and bottom blade has a radial rake angle (angle α) set to a negative angle, the radial rake angle of the outer peripheral blade 6 being -20° to -10°.SELECTED DRAWING: Figure 4 |
