Radius endmill and machine tool using the same, and designing method and machining method of radius endmill

A radius endmill, comprising:

• a tool body having
• a bottom surface at a distal end portion thereof,
• a side surface, and
• a side circular arc edge provided on the side surface thereof,
• wherein the side circular arc edge is formed starting from a third position defined at a third corner point in the side surface forming a tangential line in a direction parallel to a central axis line of the tool body, and terminating on a fourth position at a fourth corner point intersecting with the bottom surface of the tool body at the distal end portion, in a vertical section including the central axis line, in which the side circular arc edge forms a discontinued radius of curvature interrupted at the intersection with the bottom surface, and
• an angular range of the side circular arc edge from the third position in the side surface to the fourth position intersecting with the bottom surface is equal to or less than 30° in the vertical section.

A radius endmill, comprising:

• a tool body having
• a bottom surface at a distal end portion thereof,
• a side surface,
• a bottom circular arc edge provided on the bottom surface at an outer periphery thereof, and
• a side circular arc edge provided on the side surface thereof,
• wherein the bottom circular arc edge is formed starting from a first position defined at a first corner point in the bottom surface forming a tangential line and perpendicularly intersecting a central axis line of the tool body, and terminating on a second position at a second corner point intersecting with the side surface of the tool body, in a vertical section including the central axis line, in which the bottom circular arc edge forms a discontinued radius of curvature interrupted at the intersection with the side surface,
• the side circular arc edge is formed starting from a third position defined at a third corner point in the side surface forming a tangential line in a direction parallel to the central axis line, and terminating on a fourth position at a fourth corner point intersecting with the bottom surface of the tool body at the distal end portion, in the vertical section including the central axis line, in which the side circular arc edge forms a discontinued radius of curvature interrupted at the intersection with the bottom surface,
• an angular range of the bottom circular arc edge from the first position in the bottom surface to the second position intersecting with the side surface is equal to or less than 30° in the vertical section, and
• an angular range of the side circular arc edge from the third position in the side surface to the fourth position intersecting with the bottom surface is equal to or less than 30° in the vertical section.