Machine tool and workpiece inner surface machining method using the machine tool

a a aa To provide a machine tool not only capable of machining an inner surface of a workpiece into a spherical surface but also capable of machining a bearing surface including a flat surface and machining the combination of a spherical surface and a flat surface, and to provide a workpiece inner surface machining method using the machine tool. A machine tool includes: a workpiece holding mechanism holding the workpiece ; a tool having a supporting member and a cutting tool which is supported to be pivotable about a pivot axis b located on a plane perpendicular to an axis a of the supporting member and has a cutting edge at least at one end; an axial feed mechanism rotating the supporting member about the axis a and moving the supporting member in a direction of the axis a; a pivot driving mechanism pivoting the cutting tool about the pivot axis b; and a machining control mechanism controlling a pivot angle θ of the cutting tool decided by the pivot driving mechanism and a rotation speed and a position in the axis a direction of the supporting member decided by the axial feed mechanism , so as to make a machining point P by the cutting edge move along a desired machining line.