Dynamic/Static Characteristics Analysis And Optimal Design Of Square Ram Of Gantry Machining Center

The machine tool is the key manufacturing equipment for the machanical manufacturing industry. With the development of manufacturing industry, it is extensively applied to equipment manufacturing, transportation, petrol chemical industry, the aerospace industry, national defense industry and so on. So there is more of requirement for its performance, quality and quantity. The level of machine tool industry and penetration has become an important indicator of measuring a country’s comprehensive national strength and industrial modernization. China is a big manufacturing country of machine tools, as well as consumption, rather than a strong one. The traditional structure technology is dominantly based on experience analogy, which is conservative and only focus on its static nature while ignoring the dynamic nature, resulting in a little lower design ability, and it’s difficult to meet the requirement of high speed, efficiency, precision and flexibility.On the basis of summing up study on dynamic and static analysis, optimization and vibration analysis of machine tools structure at home and abroad, this thesis regards the square ram, one of the important parts of the Gantry Machining Center, in regret, as the object of research. In this paper, Finite Element modal analysis, Static characteristics analysis and optimization were performed by means of the finite element analysis software ANSYS Workbench; Test modal analysis and vibration test were also experimented by dynamic signal analyzers. The research details are as follows:First, the first part of the study is about the modal analysis and modeling. In this part, test modal analysis was experimented by dynamic signal analyzers to get the vibration and frequency of square ram. And then the modification model of square ram was obtained by adopting the combined method of experimental analysis and finite element modeling.Then, the second part of the study is about static analysis and optimization. In order to reduce the weight of the square ram and improve its performance, overall size optimization and local shape optimization were performed by means of the finite element analysis software ANSYS Workbench. First, sensitivity analysis was implemented on the critical dimensions of the square ram. Secondly, size optimization was conducted on the selected dimensions based on the sensitivity analysis results. Finally, static analysis was taken again to determine the location of the maximum total deformation, where the local shape optimization was finally performed to achieve the objectives.Finally, the vibration sources and the structure weakness were found out by means of free running experiment and cutting experiment at different spindle speed. Also, some decreasing vibration methods were proposed, which offers reference and basis for reforming the structure of angularly deflecting milling head and enhancing machining accuracy.