| 摘要 |
An improved solid cemented carbide ball nose end mill is provided which enables a cutting of a quenched or hardened difficult-to-machine material without any chipping or break of edge under the condition of a high speed and high load cutting. The improved end mill comprises a substantially semi-spherical ball nose portion provided with such cutting edges as to form a virtually S-shaped symmetrical configuration as viewed from the tip end and a tool body integral with said ball nose portion and having a peripheral cylindrical portion being provided with no peripheral cutting edge and a shank at the rear end thereof. The cutting edges extending from the tip end of the ball nose portion to the respective terminals positioned at the furthest at the vicinity of the border between the ball nose portion and the tool body are formed in the ball nose portion only. Preferably, each of a rake angle and a relief angle of the cutting edge is set between 0 DEG and -10 DEG , and between 6 DEG and 16 DEG , respectively, further the cutting edges are coated with a titanium-aluminum nitride based material film.
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