| 摘要 |
A drill of the present invention includes a first cutting edge and a second cutting edge each located at a front end of a cylindrical cutting part; a first flute and a second flute connected to the first cutting edge and the second cutting edge, respectively, in which the first and second flutes are positioned helically from a front end to a rear end on a peripheral section of the cutting part; and a first land and a second land each extended from the front end to the rear end on the peripheral section of the cutting part, in which the first and second lands are being located portions between the first flute and the second flute, respectively. The first flute and the second flute are separately extended from the front end to the rear end. The cutting part includes a first region in which a diameter of an inscribed circle in a cross section perpendicular to a rotation axis of the cutting part increases in a direction away from the front end and toward the rear end. A method of cutting a workpiece using the drill is also provided. |
