| 摘要 |
PROBLEM TO BE SOLVED: To provide a solid gun drill which has high tool stiffness. SOLUTION: In the solid gun drill 1, a cutting edge portion 5 of the drill is formed at the tip end of a tubular body 2, which is made of cemented carbide and has a segmental circular section. A continuous back taper is provided from the cutting edge portion 5 toward a driver 3 without a step in order to improve the tool stiffness. The axial length L<SB>1</SB>of outer peripheral relief portions 9a, 9b formed at the cutting edge portion 5 is determined to be shorter than the groove length L<SB>2</SB>of a chip discharging groove 4 in the range from 10 to 50 times of the diameter of the drill. COPYRIGHT: (C)2003,JPO
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