A Research About Dynamic Parameter Identification Of A Machine Fixed Combination

Today, the equipment manufacturing industry is developing rapidly, the processingperformance of CNC machine tools also put forward higher requirements, especially thedynamic performance of machine tools itself. Studies have shown that the joints of machinetools have signicant influence on the dynamic behaviour of machine tools due to creation ofstiffness and damping. How to predict the kinetic parameters of machine tools accurately atthe design stage is the primary key issues to resolve during the process of machine tools`design and reconstruction. However, the processing of joints has been the key problems toinfluence the dynamic design and simulation accuracy in the dynamic modeling of machinetools. Based on this critical issue, this paper carried out the following research:Establish a bolted-joint element model which is the common representative joints in themachine structure. This model took the coupling relationship between the DOFs of everynode of joint element into account, which can simulate the dynamic characteristics of jointsmore accurately and improve the simulation accuracy of machine tools.Based on the dynamic characteristics of experiments in the unit area of joint surface,using the Ji-cun-yun-xiao method to identify the dynamic parameters of the joint surface. Firstof all, establish the dynamic model of the joint surface; secondly using the Ji-cun-yun-xiaomethod to identify the normal and tangential stiffness and damping of machine tools whichhave the joint surface; then we will model and modal analysis to machine tools in the finiteelement analysis software using the parameters which are get by the Ji-cun-yun-xiao method.Modal test on the machine tools by using the DASP modal test system to get the naturalfrequency and damping ratio from a fixed combination of machine tool by analysising thefrequency response function that was measured, so we could get the modal graph of themachine tool. Contrast to the natural frequency of the finite element modal analysis andmodal testing to verify the effectiveness of this method using modal test results as abenchmark when the modal graph are similar.It can reduce the experimental and ensure accuracy by using this method to identifyparameters for a fixed junction of machine tools, this method which provide an importantbasis for transformation and optimization of machine tools can be directly applied to theactual structure of machine tools.