| 摘要 |
PROBLEM TO BE SOLVED: To machine a plurality of grooves at the same time by suppressing cutting resistance. SOLUTION: First to eighth cutting edge parts 4 to 11 are arranged in a row with suitable intervals in between along an axial direction of a tool main body which is rotatable around an axis. Each of the first to fourth cutting edge parts 4 to 7 has two cutting edges arranged with a 180 deg. intetval and arranged in a row provided with a 90 deg. phase difference between each of the cutting edge parts 4 to 7. Each of the fifth to eighth cutting edge parts 8 to 11 has three cutting edges arranged with a 120 deg. interval and arranged in a row provided with a 60 deg. phase difference between each of the cutting edge parts 8 to 11. By this, a plurality of grooves is formed at the same time, and also cutting resistance is suppressed during cutting work because the plurality of cutting edge parts have different phases and the cutting work is suppressed from being performed at the same time for reducing impact during the cutting work.
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