| 摘要 |
PROBLEM TO BE SOLVED: To cut a workpiece well while preventing the formation of burrs and high edges even in the case of cutting the workpiece with a metal layer on one side. SOLUTION: Out of a plurality of first spacers 15, 15A provided on a first shaft body 11, the first spacer 15A provided between upper cutting blade bodies 13, 14 of one set, and upper cutting blade bodies 13, 14 of the adjacent set, i.e., the first spacer 15A provided between the respective sets, is provided with lead-in parts 20 for allowing lead-in of lower cutting blade bodies 16, 17. The lead-in part 20 is formed in gradually recessed shape toward the end part from the center part in the axial direction of the surface of the first spacer 15A. COPYRIGHT: (C)2005,JPO&NCIPI
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