| 摘要 |
<p>A multiple-edged ball end mill which is equipped with a shank part, a cutting edge part having a ball part, and at least three cutting edges each having a ball edge. Therein: concave inclined edges integrally extend from the tips of each ball edge in the vicinity of the rotational centre of the tip of the ball part as far as the rotational centre; each concave inclined edge has an arch-shaped section which is at least curved rearward to the rotational direction; each concave inclined part is inclined at an inclination angle (alpha) of 0.5-3° relative to the plane perpendicular to the rotational axis, such that the rotational centre is located rearward in the rotational axis direction; the proportion, in the radial direction, of the length of arch-shaped section in each of the concave inclined parts is 20-100%; in each of the cutting edges, the width, in the circumferential direction, of the flank surface at the connection point between the concave inclined edge and the ball edge is 20-80% of the maximum width, in the circumferential direction, of the ball edge; and the length (X), in the radial direction, of each of the concave inclined edges is 1.25-3.75% of the cutting diameter (D) of the cutting edge part.</p> |
