| 摘要 |
A ball end mill exhibiting extremely excellent practicality in which machining surface roughness can be improved while prolonging the lifetime. On the outer circumference of a tool body, a plurality of spiral chip discharge grooves are formed from the distal end toward the proximal end of the tool, and a ball blade (15) is provided at the intersection ridge line of the face of the chip discharge groove and the flank (14) at the distal end of the tool body. In such a ball end mill, two or more ball blades (15) are provided at the tip of the ball end mill, and one groove (20) having a substantially V-shaped or U-shaped cross-section and extending outward from the center (O') of rotation of the tool is provided between respective ball blades (15) at the distal end of the tool.
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