| 摘要 |
PROBLEM TO BE SOLVED: To provide a drill capable of preventing entanglement of chips, by reducing generation of a cutting burr of a workpiece outlet, in a boring tool. SOLUTION: The boring tool has a primary cutting edge 1 on the drill tip, and has a tip angle half angleθ1 and a flank 3 like an ordinary drill. A secondary cutting edge 2 is a curve having a concave curve, and has a flank 4. An inclinationγ2 to the drill axis (c) in an intersection 11 between the secondary cutting edge 2 and a drill large diameter part 5, is set to 5°to 20°. COPYRIGHT: (C)2006,JPO&NCIPI
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