| 摘要 |
<p>Provided is a ball end mill comprising coolant holes, which makes it possible to increase the capacity of a chip-discharging pocket without having to shorten a short blade more than necessary, and to obtain ample chip-discharging properties even when large cuts are made in roughing processing. A plurality of hemispherical cutting blades (7) for which the rotational trajectory about an axis (O) is centered on the axis (O) are formed spaced apart in the peripheral direction at a distal end section of an end mill body (1), which is rotated about the axis (O). Some of the cutting blades (7) are long blades (7A), which are intersected over the axis (O) of a distal end of the end mill body (1), and the remainder are short blades (7B) having an inner peripheral end (P) at a position apart from the axis (O). Coolant holes (9) are formed in the end mill body (1), and the coolant holes (9) are opened on an extended line of the short blades (7B) going toward the axis (O) from the inner peripheral end (P) of the short blades (7B) at the distal end section of the end mill body (1) as seen from the distal end in the axis (O) direction.</p> |
