| 摘要 |
PROBLEM TO BE SOLVED: To cut a minimal dimensional light alloy workpiece accurately in the minimum number of processes. SOLUTION: An end mill 1 is a two-flute end mill into which a shank 2 and a body 3 are united. A body 3 has a middle part 5 and a cutting part 6 via the first and second taper parts 4a and 4b whose diameters become smaller and smaller in two steps. A projecting edge 9, which is projected out from the outside diameter of a peripheral cutting edge 7 of the cutting part 6, is provided at the corner of an end cutting edge 8. The projecting edge 9 is a rectangle and structured with a short side connected without a step for the end cutting edge 8 and a long side with a step for the peripheral cutting edge 7. The projecting amount of the projecting edge 9 (short side) is 4 to 6% of the outside diameter of the peripheral cutting edge 7 of the cutting part 6. The edge length of the projecting edge 9 (long side) is 3 to 5 times of the projected amount. A recessed edge 10 configured at the circular cutting edge is provided at the step part between the projecting edge 9 and the peripheral cutting edge 7.
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