| 摘要 |
PROBLEM TO BE SOLVED: To provide a cylindrical hole boring tool attached to a drill using a battery and capable of performing proper boring work. SOLUTION: The number of cutting chips 20 is three and the rake angleαof each cutting chip is set to over 10 degrees, preferably 15 to 20 degrees. A chamfered part 42 is formed in the edge of the flank 24 of the cutting chip in the outer side of a radial direction. A cut chip pocket 26 formed in the front side of the cutting chip is plotted into the rake face 22 of the cutting chip, a cut chip deflecting surface inclined from the middle part of the rake face to upward and forward sides (on the basis of the condition that one end of a cylindrical hole boring tool is facing downward), and overhead surface subsequent to the deflecting surface and a surface inclined from the overhead surface to downward and forward sides.
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