Study On Dynamic Characteristics Of NC Machine Tools Linear Guide Joint

As a precision linear guide components in machine tools, linear guide rail pair has been widely used in all kinds of high precision, high speed, large complex equipment with less wear, high precision characteristics, strong carrying capacity, such as CNC machine, combination machine tools. The dynamic characteristics of linear guide joints directly affect the dynamic characteristics of machine tools. So the dynamic parameters of CNC machine tool linear guide joints is studied by the theory and experiment,then the parameters are provided to establish the linear guide mathematical model.Read through many literature, summarized and dynamic performance of linear guide research status of the main problems, introduced the current combination of surface dynamics on the main research methods, presents a set of theoretical research, experimental dynamics, finite element modal analysis combined with dynamic analysis methods.First of all, the spring and damping were used to simulate the guide joints. Basing on the detailed analysis of the contacting deformation of guide, the dynamic model of joints was established and Hertz contact theory and finite element methods were applied to solve it. At the same time, according to guide working conditions, the joints test bench was designed and manufactured, The dynamic characteristics (mainly the stiffness and damping) were tested by LMS dynamic testing device (Belgian LMS company produced).Then, by the test bench, the kinds of dynamic characteristics were tested under changing the load or speed. The optimization method and the LMS modal analysis software were used to identify the stiffness and damping values of joints under different loads. The effect of loading and the relative movement speed of joints factors on the characteristic parameters were summarized.Finally, according to the test results and the influence law, the parameters identified were used to the mathematical model of VL855 NC machine tool in ANSYS Workbench for modal analysis. At the same time, the whole machine tool applied the vibration test of MIMO technology to get the actual dynamic characteristics. The theoretical analysis results and the experimental results have a consistency error which verified that the parameter identification method is feasible and correct. By using this method, the identified parameters had high precision.The method can be applied to other types of machine tools combined with the dynamic characteristics of the joints. So the results can provide reference for later machine tool design data, then to shorten the product development cycle.