Parameter Identification And Experimental Study On The Dynamic Characteristics Of The Joint Surface Of The Ball Screw Nut

With the development requiring high speed, high precision and good stability of CNC machine tools, the dynamic performance of feed system of machine tool is getting better. Ball screws were regarded as one of the key parts in feed system, whose dynamic characteristics directly affected the dynamic performance of feed system, even the machine tool. So the study on the dynamic characteristics of angular contact ball bearings played an important role.Firstly, in this paper, the testing theory of dynamic parameters about ball screws joint surface was introduced, and single degree of freedom vibration test model was established. An identification program of dynamic parameters was compiled based on modal parameter identification theory of Levy method. The feasibility of universal experimental device and accuracy of identification program was verified by modal test.Secondly, the axial loading mechanism and the pre-stretching mechanism were developed and the universal experimental device was designed. The force sensor for pre-stretching was manufactured and standardized. Then, use a shaker to incentive workbench and identify dynamic parameters.Thirdly, lots of joint surface based parameters data were obtained by analysis of experimental. The effects of dynamic parameters about ball screws joint surface were analyzed under different axial load, pre-stretching load and workbench position based on the generating mechanism of combing interface contact stiffness and damping. Then dynamic parameters database of joint surface about ball screws in the feed system was established.Finally, taking the horizontal feed system of machine tool SGM50A as an engineering application example, the modal parameters of workbench were obtained by modal test. The experimental and finite element analysis results were compared, which indicated that the error of natural frequency could be controlled within12.3%in the axial direction of ball screws when combing interface of ball screws was considered, while in the other way error is26.1%. It also proved that the dynamic parameters obtained from universal experimental device and testing system was accurate and reliable. So, the data could be provided for designers to establish the finite element model accurately, and even supply the theory basis about the optimization of feed systems and overall machine tools in future.