Dynamic/Static Characteristic Analysis And Optimal Design For Hobbing Headstock Of Vertical Machining Center

The machine tool plays an important role in the national economy. The industry level of the machine tool reflects the level of industrialization and the comprehensive national power of one country. With the development of the society, the machine tool becomes more and more important for the manufacturing industry. China is a big manufacturing country, but it isn’t a strong one. There is a certain gap in the machine tool between domestic and overseas. At present, the designs of the machine tool elements are mostly based on the experience. After the structural design, the prototype is made to test the performance by the cutting process. On one hand, the design cycle of this design pattern is long. It also has a low material utilization for the design is too conservative. On the other hand, in the design process, the static characteristics are considered much more than the dynamic characteristics. As a result, the study of the dynamic characteristics of machine tools and the application of simulation method are particularly important.On the basis of summing up study on dynamic and static analysis, vibration analysis and structural design of machine tools at home and abroad, this thesis regards the headstock of the hobbing part, one of the important parts of a vertical machining center, as the object of research. In this paper, modal analysis, static analysis and topology optimization were also performed by making use of digital simulation and experiments. The research details are as follows:First, the modal test based on ’Hammering Method’ was performed by DH5922 dynamic signal collection and analysis system and bundled software. Modal analysis based on simulation method was performed by fem software. And the first six natural frequencies and modal shapes were obtained. The reliability of the modal test and accuracy of the finite element model were confirmed by comparing the results of practical and simulation results.Then, vibration test during the free running condition and cutting condition were performed by DH5922 dynamic signal collection and analysis system and bundled software. The main vibration sources were found by means of analyzing the vibration acceleration and displacement. And the corresponding vibration reduction methods were proposed. Other possible vibration resources and the corresponding vibration reduction methods were summed up, that provided the reference for the vibration control of the machine tools.Finally, to get the stress and displacement distributing graph, static analysis based on HyperWorks simulation and analysis platform were performed on the headstock of the hobbing part. The value and position of the maximum stress were confirmed. And the structural safety was also evaluated. The value and position of the maximum displacement were confirmed, and the displacements of the central point of the front and back bearings were emphatically investigated. The results of the static analysis provided reference for structural optimization. The topology optimization based on SIMP method was performed by taking the minimum volume as the optimal object, as well as taking the displacements of the central point of the front and back bearings and maximum stress as the constraints. The 3D model of the headstock of the hobbing part was reconstructed considering the topology optimization result and the manufacturability of the model. And the dynamic and static characteristics of the reconstructed model were investigated. The lightweight was realized on the basis of improving the structure dynamic and static performance by topology optimization.