| 摘要 |
PROBLEM TO BE SOLVED: To provide a multiblade end mill capable of preventing the occurrence of deficiency of a cutting edge in the vicinity of a rotation center and providing an increased life. SOLUTION: In a multiblade end mill 1, twisted cutting edges 2 and 2 having cemented carbide cutting edge integrally formed at a ball part 7 are constituted such that their cutting edge ridges coincide with a rotation center 0 of the multiblade end mill 1. Meanwhile, tip cutting edges 3 and 3 formed of a rigid sintered substance consisting mainly of cubic boron nitride sintered substance (PCBN) and formed on one end side of a tip 11 fixed at seat surfaces 10 and 10 by brazing are constituted that its cutting edge ridge is missed in the vicinity of the rotation center 0. Thus, when cutting is effected by the multiblade ball end mill 1, since cutting of the vicinity of the rotation center is effected by the cemented carbide twisted cutting edges 2 and 2 excellent in toughness, deficiency of the cutting edge can be prevented from occurring. Since cutting of the outer peripheral side is effected by the rigid sintered substance tip cutting edges 3 and 3 excellent in wear resistance, the multiblade ball end mill 1 providing an increased life can be provided.
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