| 摘要 |
An end mill is provided to improve the cutting efficiency and the surface roughness of the cut surface of a machined object by dulling the angle of the edge. In an end mill, a plurality of outer peripheral blades(3) and gulleys(5) are spirally formed at the circumferential portion of the lower side of a cylindrical rod(2). A bottom blade(7) having an inclination from the central portion toward the outer end is formed at a lower potion of the outer peripheral blade. A planar surface section is formed at an end portion of the bottom blade which meets the outer peripheral blade.
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