| 摘要 |
PROBLEM TO BE SOLVED: To provide a stepping rotating cutting device such as a stepping drill smoothening outflow of chips for preventing chip packing to reduce breakage accidents during processing due to the chip packing. SOLUTION: Steps in a tool radial direction are formed in a groove 13 on an outer circumference of a small radial part 11 of a stepping drill 10 and in a groove 14 of a large radial part 12 to be a subland structure. An outer circumferential rakeγ1 of the small radial part 11 is set 0 deg. or more and an outer circumferential rakeγ2 of the large radial part 12 is set 0 deg. or less for making a moderate angular difference between both the rakes to prevent chips of the small radial part 12 and of the large radial part 12 from flowing into the groove 14 and 13 sides respectively.
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