A novel hybrid machine tool integrating a symmetrical redundantly actuated parallel mechanism: Design, kinematics, prototype and experiment

Abstract

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.