THREE-FLUTE BALL END MILL

摘要

A three-flute ball end mill, wherein three arc-shaped cutting blades (9) formed in a roughly semi-spherical shape having the center of their trace of rotation on an axis (O) are formed at the crossing ridge parts of three gashes (7) with flanks (8) at the tip of an end mill body (1) rotated about the axis (O) at equal intervals in the circumferential direction. A chisel part (12) is formed by disposing the inner peripheral ends (10) and (11) of the gashes (7) and the arc-shaped cutting blades (9), apart from a rotating center (C), around the rotating center (C) on the axis (O) at the tip of the end mill body (1). Also, chisel blades (13) arranged continuously with the inner peripheral ends (11) of the arc-shaped cutting blades (9) and extending to the rotating center (C) are formed at the crossing ridge line parts at the chisel part (12) between the flanks (8) adjacent to each other in the circumferential direction so as to be positioned approximately along a semi-sphere formed by the trace of rotation of the arc-shaped cutting blades (9). As a result, excellent machining accuracy can be provided while sufficiently securing the strength of the tip part of the end mill body around the rotating center thereof.