BALL END MILL

摘要

In the ball end mill, at least two end cutting edges (9) are extended to the vicinity of an axis (O) at a tip portion of an end mill main body (1) which rotates around the axis (O). In two gashes (7) in which two end cutting edges (9) adjacent to each other in a circumferential direction are formed, a first gash (7A) on the end mill rotation direction (T) side extends beyond the axis (O) on the tip of the end mill main body (1) and a second gash (7B) on the rear side in the end mill rotation direction (T) does not exceed the axis (O). A first tip flank face (8A) which intersects with the first gash (7A) through a first end cutting edge (9A) is extended toward a second tip flank face (8B) which intersects with the second gash (7B) through a second end cutting edge (9B). A concavely curved surface (10) which is concavely curved and connected to an extended portion (8c) of the first tip flank face (8A) and extends toward the outer periphery side is formed between the extended portion (8c) of the first tip flank face (8A) and the second tip flank face (8B). The second end cutting edge (9B) intersects with the concavely curved surface (10) at an obtuse angle.

主权项

1. A ball end mill comprising:
an end mill main body which rotates around an axis; a plurality of chip discharge grooves formed at intervals in a circumferential direction at an outer periphery of a tip portion of the end mill main body; and a gash which is formed at a tip portion of each of the chip discharge grooves and extends toward an inner periphery side, wherein each end cutting edge of which a rotational locus around the axis having a hemispherical shape is formed at an intersection ridgeline portion between a wall surface facing an end mill rotation direction of the gash and a tip flank face of the tip portion of the end mill main body, which intersects with the wall surface, the hemispherical rotational locus is convex toward the tip side and has a center on the axis, at least two end cutting edges among the end cutting edges are extended to the vicinity of the axis in a tip of the end mill main body, two of the gashes, in which two end cutting edges adjacent to each other in the circumferential direction among these at least two end cutting edges are formed, are formed such that a first gash which is located on the end mill rotation direction side extends beyond the axis on the tip of the end mill main body and a second gash which is located on the rear side in the end mill rotation direction does not exceed the axis on the tip of the end mill main body, a first tip flank face which intersects with a wall surface facing the end mill rotation direction of the first gash through a first end cutting edge out of the two end cutting edges is extended toward a second tip flank face which intersects with a wall surface facing the end mill rotation direction of the second gash through a second end cutting edge out of the two end cutting edges, a concavely curved surface which is concavely curved and connected to an extended portion of the first tip flank face and extends toward the outer periphery side of the end mill main body is formed between the extended portion of the first tip flank face and the second tip flank face, and the second end cutting edge extends in a direction intersecting with the concavely curved surface at an obtuse angle and is connected to the concavely curved surface.