| 摘要 |
PROBLEM TO BE SOLVED: To provide a throwaway reamer preventing generation of damage in a prepared hole by a cutting blade in the case the reamer is extracted from the prepared hole finish worked in a workpiece. SOLUTION: In this throwaway reamer, providing a throwaway chip 8 protruded to an external peripheral side of a tool main unit rotated around an axial line C in its tip end part and providing a guide pad protruded to the external peripheral side of the tool main unit to be extended in a direction of the axial line C, a land 8d having a circular arc surface (arc-shaped external peripheral surface) 8e of radius R2 of rotation with a center C1 serving as the center is provided, in a manner wherein a radius of rotation with the axial line C serving as the center is gradually lessened as the land goes toward a rearward side of a cut rotational direction T from a cutting blade 8a, in a rake face 8b facing the external peripheral side of the tool main unit of the throwaway chip 8. A width E of the land 8d is set to within a range from 0.01 mm to a half the thickness of the throwaway chip 8.
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