Using CAD geometric variation approach machining complex workpiece by a 3-SPR parallel machine tool

A novel CAD geometric variation approach is proposed for machining the complex workpiece, caving letter on a 3D free-form surface, and milling cam by a 3-SPR parallel machine tool. First, a simulation mechanism of the 3-SPR parallel manipulator is created, and a workspace of the moving platform is constructed by the 3-SPR simulation mechanism. Second, the tool path guiding plane with complex workpiece and the simulation mechanism of the 3-SPR parallel machine tool are combined to form the whole simulation mechanism. Third, the extension of the active legs and the position of the moving platform are solved automatically and visualized dynamically by using simulation mechanism. Finally, the formulae for solving displacement kinematics of the 3-SPR parallel machine tool are derived. The results of the simulation mechanism are verified by kinematic analytic results. The CAD geometric variation approach is straightforward without compiling any program.