Structural Analysis And Design Of The Supporting Part And Fixed Joint Department Of Machine Tool

With the rapid development of equipment manufacturing industry, demands for performance and structure of machine tool, which is from machining, are higher than before. The equivalent model of the fixed joint department, which is an important part, is the foundation of structural analysis and design of machine tool. The modern methods, such as topological optimization and size optimization are applied to the design of the supporting part and fixed joint department of machine tool, which shortens development period highly and improves the market competitiveness. The structural analysis and design of the supporting part and fixed joint department of machine tool has been achieved in this paper combined with the requirement of the project. The main works are contained as follows:(1) The characteristics of supporting part and fixed joint department are analyzed. Based on summing up the common equivalent model of the joint department, the equivalent model of preload-contact element is put forward with contact element used in contact area and preload element applied in the middle of bolts.(2) The load cases of the column are analyzed, and the evaluation indicator of the static performance of supporting part and fixed joint department of machine tool is put forward. The finite element model of the column is built and analyzed, in which the elastic restraint of preload-contact element is used. Parameter sensitivity analysis is carried out for cell size, preload and friction coefficient that have influences on static performance calculation of the column.(3) The distribution principle of bolt for the fixed joint department of machine tool is introduced and the fixed joint department is designed and arranged by the means of topology optimization. The finite element model of the column is built based on the elastic restraint of GAP element. The topology optimization is completed which based on optimal objectives:the weighted compliance objective of multi load cases and multi objective of static and dynamic state. The design of structural concept, rib plate scheme and technical improvement is achieved based on the result of topological optimization.(4) The evaluation indicator of the size optimization of supporting part is brought forward, with the size optimization problem of siding and rib plate of the column carried out. The multi-objective and multi-parameter size optimization model for the fixed joint department is established by means of size optimization. Parameter sensitivity analysis is carried out, and dimensions which affected the object are chosen to be as the optimal design variables.(5) The stiffness of the new column plan for the common condition, top and bottom limit condition improves13%,18.7%and17.8%separately with the mass reduced5.3%compared to the original one. The ratio of stiffness and mass of the new column plan for the common condition, top and bottom limit condition increases21.3%,29.9%and28.4%. Results indicate that the static performance of the column improves efficiently with mass reduction. The change of dynamic performance is very small with3.3%,0.3%and3.5%decrease of the first three natural frequencies, which meet the dynamic requirements of the column. Through the research in this paper, the method of light-weight design of supporting part of machine tool has been basically formed.