| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball end mill with coolant holes which can obtain ample chip-discharging properties even when large cuts are made in roughing processing by increasing the capacity of a chip-discharging pocket without shortening a short blade more than necessary.SOLUTION: 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 circumferential direction at a distal end part 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 part of the end mill body 1 as seen from the distal end in the axis O direction. |
