PROBLEM TO BE SOLVED: To cut a workpiece provided with a convex part such as a dental prosthesis having a large curvature radius and a fine uneven shape part by one end mill body.SOLUTION: A cutter part 3 is provided at the tip of an end mill body 1 rotated about an axis O. At the tip of the cutter part 3, a spherical bottom blade 7 having a central angle θ of less than 180° at which a rotation locus about the axis O has a center C on the axis O is formed. From the outer peripheral end P of the bottom blade 7 to a rear end side, a convex surface outer peripheral blade 8 that has a curvature radius R larger than that of the bottom blade 7 on a cross-section along the axis O and that comes into contact with the bottom blade 7 at the outer peripheral end P of the bottom blade 7 to swell to the outer peripheral side closer to the rear end, and then is recessed is formed.SELECTED DRAWING: Figure 4COPYRIGHT: (C)2017,JPO&INPIT【課題】歯科補綴物のような曲率半径の大きな凸曲面部分と、細かい凹凸形状をなす部分とを備えた被加工物を、1つのエンドミル本体によって切削加工を行う。【解決手段】軸線O回りに回転されるエンドミル本体1の先端部に切刃部3が設けられており、この切刃部3の先端には、軸線O回りになす回転軌跡が軸線O上に中心Cを有する中心角θが180°未満の球面状の底刃7が形成されるとともに、底刃7の外周端Pから後端側にかけては、この底刃7の外周端Pにおいて底刃7に接して後端側に向かうに従い外周側に膨らんだ後に内周側に凹む、軸線Oに沿った断面において底刃7よりも曲率半径Rの大きな凸曲線状の外周刃8が形成されている。【選択図】図4
