| 摘要 |
In the present invention, outer-peripheral blades of a formed end mill have small-diameter blade parts and large-diameter blade parts. An imaginary line obtained by lining up the deepest points of the groove bottom of a chip discharge groove, which appears in a horizontal cross-sectional view perpendicular to the axis of an end mill body, in the direction in which the chip discharge groove extends is used as a virtual groove-bottom line. In a side view seen from the radial direction orthogonal to the axis of the end mill body, a groove torsion angle formed between the virtual groove-bottom line and the axis is set as being equal to or greater than 0° at the axial-direction distal-end part of the chip discharge groove, and gradually increases from the distal-end part toward the axial-direction base-end side. |
