Study On Static And Dynamic Characteristic Of A Tripod Parallel Universal Platform

Parallel Kinematics Machine (PKM) is a new kind of manufacture equipment comes into the world in the middle of90s. Compared with conventional series machine tool, it is higher rigidity, load-bearing ability and precision, lower weight, simpler structure, and so on. Thus, PKM becomes an important development direction of new type of machine tool. The static and dynamic characteristic of parallel machine tool is one of the most important characteristic of machine tool evaluation. They directly affect the machining accuracy of machine tools and machining processing quality. Based on the preliminary study, the static and dynamic characteristic of a novel parallel mechanism, tripod parallel universal platform, is studied in this paper which can provide causes for the improvement and development.The conception, characteristics and development condition of PKM are summarized, and the advantages, disadvantages and the main developing direction of PMT are discussed. On this basis, the static and dynamic characteristic of the tripod parallel universal platform are analyzed in detail by the use of the relevant software in this paper. Then the weak point of the platform is identified, the stiffness and nature frequency are calculated, and the improvement is proposed.First, the structure of the platform is designed by the used of PROE. Then, the solid model is imported into ANSYS to change it into the needed infinite element model by necessary process. In static mechanical properties analysis, the static characteristic of the parallel platform is analyzed by the used of ANSYS software, considering the characteristics of parallel platform under the static load, to find the stress and strain diagram of the whole platform in different postures, and then to find the stress distribution rules. In the static stiffness analysis, the stiffness finite element analyze of the platform is made based on the theory of the static stiffness of the parallel platform. Then the deformation map and the stiffness value of the whole machine are got in different postures. The stiffness distribution rule and affection factor is analyzed. At last, finite element modal analysis theory and modal analysis functions of ANSYS software are used to study its nature frequency of vibration modes.