| 摘要 |
There is provided a drilling tool having a substantially columnar tool body to be rotated around an axial line, a cutting edge located at a front end portion of the tool body, and a chip suction hole which is formed inside the tool body in a direction of the axial line for sucking chips generated by the cutting edge. The chip suction hole has a main hole portion extending toward a drill base along the axial line, a narrow hole portion located at a front end of the main hole portion, the narrow hole portion having a cross section smaller than that of the main hole portion and a suction opening located at a front end of the narrow hole portion and opened in the vicinity of the cutting edge, the suction opening having a cross section larger than that of the narrow hole portion.
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