The Modal Analysis And Optimal Design Of A Certain Horizontal Machining Center

In recent years, fast-growing automobile industry in China has created a great demand of car parts processing and manufacturing. The fierce market competition requires the manufacturing develop in a precise, speed and effective way. As the basic tool of equipment manufacturing industry, the machine tool plays a significant role in the development. At present, there are a variety of machine tools in China; however, due to the lack of the key technologies and the use of new techniques lags behind the foreign companies, the high-end product market is still controlled by them. Thus, in the tide of the industry 4.0, it is important for us to develop an excellent machine tool production. The performance of the machine tools depends on its dynamic characteristic. It is inevitable that dynamic characteristics analysis will merge into the process of designing the machine tools and replace the traditional static analysis.Based on The Science and Technology Major Projects of Liaoning Province, the purpose of this study is to improve the performance of a new precision horizontal machining center model by studying on its dynamic characteristics. First, on the basis of introducing the modal test principle, the natural frequencies, mode shapes and damping ratios of the subject were obtained through the experimental modal analysis method. Second, an accurate simulation model of the machine tool was gained by processing the bolt joint surface between the column and bed through Masataka Yoshimura method, and the model was also verified by comparing the simulation and experimental results. Finally, the study made the harmonic response analysis through using the same model, and two weak links, the machine frame structure and the foundation, were found by analysing the modal and harmonic response results, which pointed out the optimization direction of dynamic performance.To improve the dynamic performance, first, the optimal combination of the frame structure's five parameters was obtained by means of parametric design, sensitivity analysis and response surface optimization method. Then, the optimal installation position of the pressing-plates was gained by orthogonal test method, and the method also reached a conclusion that increasing the bolt joint surface stiffness between the pressing-plates and bed is beneficial to improve the overall machine dynamic performance. After the synthesis optimization, the natural frequencies of overall machine had been improved on average by 34.5%, and the highest harmonic response peak had been fallen by 25.3%, which provided a reference for the machine tool upgrading.