Processing Center-state Analysis Of The Whole Test Mode And The Main Junction Parameters Identification Method

With the development of modern science and technology and the improvement of manufacturing technique and advanced tool, machine tool should have the capabilities of high production efficiency and accuracy .In order to fulfill the requirements of the modern production, The structure of machine tools should have satisfactory dynamic characteristics.Today the analysis and study of dynamic characteristics of structure occupy an important place on design and manufactory of new type machine tools.Experimental modal analysis is such kind of a method which provides a base for amending system structure by extracting system modal parameters from experiments.Study and engineering application of lathe structure dynamic characteristic have already made very great progress, but to the specific machine tool, the dynamic analysis taking improving its machining accuracy as specific goal still includes a lot of theories needing to be solved and technological problem.Based on the project "modern design method research of machining center of boring and milling" sponsored by Yunnan Province Natural Science Fund, the dynamic characteristics for the complexity of machine center is studied in this paper with combination method of theoretical and experiment model for the purpose to improve the rotate speed and the stability of machining center.The theory and its application such as modeling, dynamic experiment, parameter identification for the whole machine and for joints were comprehensively and systematically studied in this paper.The main work of the article is as follow:(1) The actuality of dynamic characteristics research for machine tools' structure was analyzed roundly and systematically, and the problem and shortage was pointed out.(2) Based on the theory of modal analysis, experiment skill, parameter identification and signal analysis, an experiment system of correlated dual-input was set up.With proper exciting method and equipment, the actual force in machining process was better simulated.Several test schemes which include monitoring sensor, oscillation and data sampling analysis system, together with the equipmentadjustment, debugging and parameter setting, were detailed in the paper.Afterwards, dynamic tests to machining center were processed by using sine wave excitation, pseudo random excitation and impact experiment methods.(3) The frequency-domain parameter identification method was used after the experiments, through which system mode parameters, system characteristic curve and system mode shape were obtained.The system dynamic characteristics were exposed well by curve fitting validity.(4) Through the analysis of the main modes of structure, the principal parts producing the vibration were obtained.The suggestion to machine tools' structure optimal design was submit.(5) Dynamic tests on main shaft system, main shaft-frame- bed system and entire machine were conducted.Frequency Response Functions(FRFs) of each part were obtained, the way and algorithm to identify the parameter of joints was analyzed, which become the foundation of joints parameter identification.