| 摘要 |
PURPOSE: A center drill having dual point angles is provided to improve the machining accuracy of a workpiece through a structural change regardless of the kind of machining equipment. CONSTITUTION: A center drill(20) having dual point angles comprises a front end part(30) formed in the bottom end of a shank unit. The front end part has first and second front end(31,32). The first and second front ends are concentrically formed and have different point angles(A1,A2) and different diameters(D1,D2) from each other.
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