| 摘要 |
PROBLEM TO BE SOLVED: To eliminate increase of the cutting resistance by smoothly curling chips generated by a thinning cutting blade part to excellently keep the chip discharging property. SOLUTION: A thinning part 20 continued to an inner peripheral end side of the cutting blade 14 is formed in a tip side of the inner wall surfaces 13A and 13B of a chip discharging groove 13. The thinning part 20 is formed into a valley shape having a recessed valley bottom part 24 with a curve extended toward the inner peripheral end of the cutting blade 14. Curvature radius of the recessed curve formed by cross section of the valley bottom part 24 is set to increase toward the outer peripheral side. COPYRIGHT: (C)2004,JPO&NCIPI
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