| 摘要 |
PROBLEM TO BE SOLVED: To prevent the mouth of a shank forming a pipe shape being closed by cement or foreign matter in cutting liquid, in a drilling tool such as a gun drill and a gun reamer. SOLUTION: A blind hole 5 having a larger diameter d than the diameter D of a shank 2 is bored from the rear end of a driver 3. The shank 2 is passed through a junction hole 6 provided at the tip of the driver 3 while having a diameter almost equal to D, and is joined with its tip protruded in the blind hole 5.
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