| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an end mill having a small diameter of 2 mm or less, preventing occurrence of chatter or damage even when an actual cutting depth is shallower than a recommended one, improved in cuttability, having a long service life and improved in processing accuracy.SOLUTION: There is provided an end mill in which a diameter is 2 mm or less, a bottom blade 13 has a concave angle from an outer peripheral end toward an axial center, and a horning face 17 is formed on the ridge line of a rake face 14 and a flank 16. The horning face 17 is formed on a projectingly curved face being a part of ellipsoid disposing a long axis so that a cross section orthogonal to the ridge line passes through the horning face 17 in at least outer peripheral end of the bottom blade 13. The horning face is formed so that when the major axis of the ellipsoid is defined as 2a and the minor axis as 2b, a/b becomes gradually small in the range of 6 to 1 as proceeding to the inside in the radial direction of the bottom blade 13.</p> |
