| 摘要 |
PROBLEM TO BE SOLVED: To restrain an increase in manufacturing cost and attain stability to breakage in deep hole work of a small diameter drill with sintered diamond used for boring a hole of a hard fragile material. SOLUTION: In this small diameter drill, the axial directional length of a flute is 2 to 20 times a diameter of a tip cutting edge, and the axial directional length of a body is longer by 30% or more than the axial directional length of the flute. A diameter of the body is set smaller than the diameter of the tip cutting edge in a range up to a shank side tail end part of the body from the shank side tail end part of the flute, and cutting performance is improved in the deep hole work more than a conventional drill, and the breaking is little caused by preventing reduction in tool rigidity. Manufacture is also facilitated, and an increase in the manufacturing cost is restrained. COPYRIGHT: (C)2004,JPO
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