| 摘要 |
PROBLEM TO BE SOLVED: To heighten the boring accuracy by avoiding elastic distortion in machining in boring a workpiece easy to bend in a specific burnishing boring tool. SOLUTION: A roughing blade step part 12 is formed on the outer periphery of a shaft 2 extending between one drill groove 4 and one reamer groove 6. Finishing blade step parts 17, 18 are formed extending between the other drill groove 4 and the other reamer groove 7 and between one reamer groove 6 and the other reamer groove 6. The roughing blade step part 12 and the finishing blade step parts 17, 18 have ceiling surfaces 14, 20 and an outer peripheral surface. The dimensional difference W12 between the radii R13, R19 of the outer peripheral surface of the shaft 2 and the radius R15 of the outer peripheral surface of the roughing blade step part 12 is set ranging from 0.1 to 0.15 mm, and the dimensional differences W17, W18 between the radii R13, R19 of the outer peripheral surface of the shaft 12 and the radius R21 of the outer peripheral surface of the finishing blade step parts 17, 18 is set ranging from 0.3 to 0.5 mm. COPYRIGHT: (C)2006,JPO&NCIPI
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