| 摘要 |
PROBLEM TO BE SOLVED: To permit the working with a large amount of cutting by recessing a blade tip of each cutting blade of a step type cutter in the axial direction and the radial direction. SOLUTION: Stepped cutting blades 1a, 1i, 1j of a step type cutter are fixed to the periphery of a cutter body. A blade tip of each cutting blade is formed with a stage difference (recessed part) (a) in the axial direction and a stage difference (b) in the radial direction. The step-like stage difference (recessed part) (a) of each cutting blade is formed several times as large as a step-like stage differenceΔd of each cutting blade. In the case where the cut amount of each cutting blade is expressed withΔd, the number of blade is expressed with N and the number of step of each cutting blade is expressed with (n), the cut variable (d) in the axial direction is obtained with an equation (d)=Δd×N×n. Consequently, cut amount in the axial direction per one blade can be secured large while restricting the fed amount small, or the cut amount in the radial direction per one blade can be secured large. With this structure, efficient cutting is realized.
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