Patent attributes
A ball endmill having a cylindrical tool body and ball-nosed end cutting edges each of which includes a first portion and a second portion continuous to the first portion. The first and second portions are located at a radially inner portion of each ball-nosed end cutting edge in a distal end view. The first portion is convex in a direction of rotation of the tool body and has a first radius of curvature seen in a distal end view. A ratio of the first radius of curvature to an outside diameter of the cylindrical body is between 0.025 and 0.10. The second portion is convex in the direction of the rotation of the tool body and has a second radius of curvature as measured in the distal end view. The second radius of curvature is larger than the first radius of curvature.
