| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To efficiently carry out work to drill holes with various hole diameters larger than the tool diameter of a drilling tool with respect to nonferrous metal such as aluminum. <P>SOLUTION: The drilling tool comprises a tool main body 10 that is rotatable, provided on a tip part with a front surface main cutting blade 11 radially extended over a rotation center, and a front surface subsidiary cutting blade 12, radially extended without reaching the rotation center, with a torsional groove 13 formed along an outer circumferential part, and an outer circumferential cutting blade 14 formed along the torsional groove. The tip angleθof the tool main body is set to make 180°<θ≤210°, and the core thickness d with respect to the tool diameter D is set to make 0.4≤d/D≤0.65. The front surface main cutting blade is set to deflect from the rotation center toward the rotation direction upstream side as it is in a radially parallel state. The drilling tool is rotated to be axially fed, while the drilling tool is revolved along a circular track smaller than the tool diameter D for drilling. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
