Abstract
A novel 5-degrees-of-freedom (DOF) 3SPS+RRPU parallel machine tool (PMT) and a novel 5-DOF 2SPS+RRPRR PMT are proposed for a three-dimensional (3D) free-form surface normal machining. A computer aided design (CAD) variation geometry approach is adopted for solving the extension/rotation of linear/rotational actuators and the pose of the two PMTs during machining. First, two simulation mechanisms are created by the CAD variation geometry technique for the 3SPS+RRPU PMT and the 2SPS+RRPRR PMT, respectively. Second, a 3D free-form surface and a guiding plane of tool path are constructed above the moving platform of the simulation mechanism. Third, the tool axis of the simulation PMT is kept normal to the 3D free-form surface, and two 5-DOF simulation PMTs are created. Finally, in the light of the two prescribed tool paths, the extension/rotation of linear/rotational actuators, and the pose of the PMTs are solved automatically and visualized dynamically.