Structural Design Of The Fixed Connection And The Headstock In Machine Tools

Machine tool industry is the foundation of the manufacturing industry. Structural design for fixed connection and its supporting members are important links in the process of machine tool design. With the development of manufacturing industry, the experiential analogism method and evaluation index cannot meet the design requirements of fixed connection and machine tool completely. Considering problems of structural design for fixed connection and supporting members, this article completed fixed connection structural classification. The design method of bolt layout area in fixed connection is put forward based on the topology optimization. A multi-objective optimization model of connection structural parameters is established for the headstock, and the response surface method is used to determine arrangement parameters and connection structure size. The structural design of the headstock has been completed based on the fixed connection using structural optimization design method of supporting members. Specific works are as follows:(1) Kinds of fixed connection structures in machine tools are classified as embedded structure and flange structure. Performance analysis has been carried out to study the influence of different structural form and fixed connection structural parameters. Static performance analysis of two structural form has been carried out and find that the just mass ratio of embedded structure is bigger than that of flange structure in normal (Z) direction and (Y) direction. Comparing the influence of bolt diameters and bolt arrangement spacing to the stiffness of the connecting structure find that bolt layout spacing is the main factor.(2) Considering the static and dynamic performance of fixed connection and its supporting members, the analysis has been carried out to study the influence of load form and size to bolt layout region by topology optimization technology. The bolt layout region design method is put forward based on topology optimization technology, and the optimization design of bolt layout region of the headstock is completed using the method.(3) A multi-objective optimization model of the fixed connection structure is established with the fixed connection structure of headstock in machine tools, and the structural parameters optimization design process based on response surface method is proposed. Three bolt layout forms are proposed based on the bolt layout region, and bolt arrangement parameters and embedded structure parameters have been optimized based on the response surface method with workbench platform. Finally, a new connection structural model is constructed. Through the comparative analysis of new and original connection structure, displacements of the spindle in the pre and post end of the headstock are reduced by 12% and 33% while the dynamic frequency increased by 5%.(4) The evaluation indexes, just mass ratio CQ、CH and natural frequency, of the structural optimization for supporting members are used to evaluate static and dynamic performance of the headstock.Then the structural design of the headstock is completed based on the structure of fixed connection schemes using structural optimization design method of supporting members. The comparative analysis has been made to the original and new headstock. The weight of the headstock loss of 2.4% and the just mass ratio is increased by about 10% in front of the headstock while the just mass ratio is increased by more than 2.3%. The fundamental frequency of headstock increased by 3.5%.