A Novel Hybrid Machine Tool Integrating a Symmetrical Redundantly Actuated Parallel Mechanism : Design, Kinematics, Prototype and Experiment

Hybrid machine tools are suitable for machining structural components with complex geometries due to their merits of flexible posture adjustment and quick dynamic response. This paper proposes a novel hybrid machine tool with 5-axis machining capability by integrating a newly invented redundantly actuated parallel mechanism (RAPM). For this purpose, a screw theory based type synthesis methodology is proposed to synthesize a RAPM with a topology of 2PRU-(2PRU)R. The synthesized RAPM is conceptually designed as a spindle head, which is characterized by symmetrical limb arrangement and usage of only PRU-type kinematic chains. The spindle head is further integrated with a two-sliding gantry to construct a novel 5-axis hybrid machine tool. The kinematic performances of position and singularity of the proposed hybrid machine tool are analyzed. After then, a laboratory prototype of the hybrid machine tool is engineered and an open-architecture numerical control system is developed to perform 5-axis machining tasks. The large orientation capacity and 5-axis machining capability of the hybrid machine tool are verified by some motion experiments and machining tests