滚珠丝杠进给系统动态特性集中质量建模与仿真

为了研究高速滚珠丝杠进给系统的动态特性,提出一种改进的集中质量建模方法,该方法考虑了滚珠丝杠进给系统基座的质量、柔性及进给系统部件间反向间隙对系统动态特性的影响,并完善了滚珠丝杠进给系统集中质量模型等效参数的计算方法。以MAG某加工中心X轴滚珠丝杠进给系统为实验对象,对该集中质量模型建模方法进行实验验证,仿真结果与实测结果具有相同数量的特征频率,且特征频率的误差在5%以内。滚珠丝杠进给系统的仿真分析表明,螺母位置改变引起的进给系统固有频率变化将影响伺服系统的稳定性,滚珠丝杠进给系统中的反向间隙会激励部件产生高频振动,给进给系统带来不利影响。

Dynamic Characteristics Modeling and Simulation of Ball Screw Feed Drive System Based on Lumped Mass Model

High speeds and acceleration create high reactive forces between the moving mass and the stationary bodies of the ball screw feed drive system and excite the structure which causes undesired vibrations. Therefore, it is necessary to have an accurate dynamic model of the feed drive system for machine design and controller tuning. An optimized dynamic modelling and simulation method of a ball screw feed drive was presented based on the lumped mass model. The mass and the rigidity of the ball screw feed drive basis were considered in this new model and the calculation method of the equivalent parameters was optimized. Simulative and experimental examinations were conducted based on an X -axial ball screw feed drive system on a MAG machining center and the presented method was proved to be accurate because of the same eigenfrequency number and the limited error (less than 5%) between the simulated and measured eigenfrequencies of the ball screw feed drive system. Based on this model the vibration characteristic of a ball screw feed drive system was studied. The simulation results showed that the natural frequency change caused by the nut position change affected the stability of the servo system, and the backlash of feed drive system encouraged the components to produce high-frequency vibration and made the servo system unstable.