| 摘要 |
PURPOSE:To prevent vibration occurrence for improving cutting performance and a finished surface by setting a helix angle of at least one cutting blade of an end mill to be different from helix angles of other cutting blades. CONSTITUTION:A helix angle, between two cutting blades 13a, 13c positioned with the rotary center O placed in-between among four cutting blades 13a-13d formed on the edge part of an end mill body 11, is made to be theta2, and another helix angle between the other two cutting blades 13b, 13d is made to be theta2 while setting the relation between them to be theta1<theta2. Frequency of vibration caused when the respective cutting blades cut a work acts as in such a way as offsetting each other for preventing vibration from occurring on the end mill body, so that cutting performance can be improved.
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