Design And Optimization Of Parallel C - Type Gantry Milling Machine Frame Structure

3-(2SPS) parallel machine is different from previous parallel machines. Its rack (fixed platform) uses an open structure in order to obtain a larger work space. This design will decrease the whole machine’s stiffness compared to most closed structure parallel machine. Therefore, take the rack as the research object and carry out its corresponding structure design, simulation and optimization. The main work is as follows:(1) Take the position analysis and force analysis of the 3-(2SPS) parallel machine. Based on a given working parameters and load cases, the force situation of the six ball hinges are obtained which lay a foundation for the whole rack static analysis.(2) According to the rack manufacturing solution, using the modular concept to design the rack which contains the upper supports, main column and the lower supports. Among this three components, make a detail introduction of the column’s design.(3) First of all, analyze the static performance of the column and get the conclusion that the column’s stiffness is insufficient. Finally, the column’s static stiffness meets the requirements through the structure improvement and size optimization. At the same time, the optimal design dimension of the rack’s cross section is obtained.(4) After the column’s stiffness meets the requirement, analyze the static and dynamic performance of the whole rack. Through static analysis, the reason of insufficient rigidity and the rack’s weak area are found. Then some corresponding improvement suggestions is proposed. In the dynamic analysis, the rack’s dynamic performance is presented by taking modal analysis and harmonic response analysis.(5) The structure improvement of the rack is taken based on the results of its static and dynamic performance. Though adjusting the column’s design size, increasing the inner ribs of the upper supports and making a detail design of the column’s back plate, the rack’s the static stiffness and dynamic performance finally meet the requirements of machine design precision.