| 摘要 |
PROBLEM TO BE SOLVED: To provide a drill capable of continuously executing more cutting work of a high-tensile steel plate. SOLUTION: The drill 1 has a substantially columnar shaped drill body 2 having a rake face 4 therein and rotated around the axis O, and a chisel 7 is projected from a flank 6 at a fore end of the drill body 2. The chisel root angleθwhich is an angle formed by a cutting blade 5 formed of the rake face 4 and the flank 6, and a chisel cutting blade 7b continuous to the cutting blade 5 and formed by the rake face 4 and the chisel 7 is formed to be larger than 151.6°. Further, the chisel root length W is formed to be≤5.0 mm. COPYRIGHT: (C)2011,JPO&INPIT
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