| 摘要 |
PROBLEM TO BE SOLVED: To perform high efficient rough cutting, and also, to keep the surface coarseness of a processing side satisfactory. SOLUTION: While forming six sheets of perimeter cutting edges 15... on the periphery of a body of a tool 11, six sheets of near circular-arc form of R cutting edges 19... which follow the perimeter cutting edges are formed in the tip part of the body of the tool 11. In the section which intersects perpendicularly with the axis line O, a diametrical rake angleαof the perimeter cutting edges 15 is set -20 deg.<=α<=0 deg., and, a diametrical rake angleβof the R cutting edge 19 is setα<β<=5 deg.. To workpiece which is made from high hardness material, the R cutting edges 19... and the perimeter cutting edges 15 are made to act simultaneously and rough cutting is performed.
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