Dynamic Analysis And Simulation Of Synchronous Dual Ball Screw Feeding System Used In A Milling-turning Compound Machining Center

With the rapid development of computer numerical control (CNC) machine tools, higher requirements for high speed, heavy load, highly precision and high efficiency of machining centers are required. Under the condition of high speed and heavy load, the dynamic performance of transmission system of machining center has great influence on the positioning accuracy and machining quality of the whole machining center.Therefore, it is important for us to perform the dynamic analysis and study for transmission system.This paper focus on the double-drive feed system of milling combined machining center. On the premise of assuring stable feed and machining accuracy of worktable at high speed and heavy load, the dynamic analysis and simulation of transmission are employed based on the finite element method and virtual prototype technology. Furthermore, several major research results are show as follows:1. The whole machine model of milling combined machining center is established. According to the influence of structure features and the center of gravity of the beam on transmission system, the model is simplified reasonability, and the model of double-drive-feed system is got. Moreover, the foundation for the finite element analysis and simulation is provided.2. The dynamic model of double-drive-feed system is established. Based on the consideration of each joint surface and the displacement or perturbation along different directions on beam, the equivalent stiffness and equivalent damp are calculated by the means of integral method proposed by Takashi Yoshimura. Beside, the natural mode is calculated based on the kinetic equation established by Lagrange energy method.3. The mode analysis and harmonic response analysis are performed for double-drive-feed model. Comparing the numerical results obtained by mode analysis with theoretical analysis, the reasonability of model established by simplified method can be got. Beside, the frequency value of resonance is got by harmonic response analysis. Moreover, the improving suggestions for weak link of double-drive-feed system can be got by analysis the map of model shape.4. The ball screw is simplified as flexible based on the virtual prototype technology. The rigid-flexible coupling model of double-drive-feed system is established by ADAMS. The motion simulation of the system is performed in ADAMS, and the acceleration curve of the beam is obtained, finding that the mid-position of the two load screws easily produce vibration. Besides, the optimization of the parameter for the span between the two load screws is employed under the objective function of the maximum of amplitude-frequency curve at any points on the beam, so the reasonable location dimension of the span is got.