Quantitative analysis for effects of structural stiffness on vibration characteristics of machine tool feed system

Abstract

The vibration of the feed system remains a long-standing challenge in a machine. Toward this objective, the effects of bearing stiffness, nut rigidity, coupling stiffness, screw length, screw speed and radial stiffness of worktable on the torsional vibration and axial vibration of the table are explored. In this paper, a mathematical model of multi-degree-of-freedom coupling torsional and axial vibration considering various factors is established by the second Lagrange equation, and simulation analysis and experimental verification are carried out. The effects of the variable lead and variable torsional stiffness of the nut on the torsional vibration of the workbench are analyzed. Results show that nut stiffness is the main factor affecting the vibration of the workbench. As the workbench mass, motor speed, screw length and lead increase, the axial vibration of the workbench increases. In the case of lead change, as the axial stiffness of the nut increases, the effect on the torsional vibration of the workbench is reduced. Under the variable torsional stiffness of the nut, with the increase of the lead, the influence of the lead on the torsional vibration of the workbench will increase. The experimental results provide a reference for further research and provide a theoretical basis for vibration reduction and structural optimization.

Study of dynamic vibration characteristics and suppression of CNC machine tool during operation

“…Additionally, considering various other characteristics of abnormalities among data (such as scarcity and diversity), a new approach is designed to detect abnormal behavior using normal patterns instead of abnormal patterns from machines [17]. Liu [18] discussed the influence of stiffness in nut, coupling, radial, along with the length and speed of screw on table vibration of torsional and axial vibration. The second Lagrangian equation is used to establish freedom of multiple degree for vibration of axial torsional coupled mathematical model which takes various factors into account.…”

“…The influence of variable lead and variable torsional stiffness on the torsional vibration of the table is analyzed. It is observed from the experimental results provide that the design provides future research and theoretical reference for vibration reduction and optimization of structure [18]. Wang, et al used PROOE software to build a THREE-DIMENSIONAL model of a five-axis CNC machine tool.…”

Dynamic analysis of ball screw feed system with abrupt-change-nonlinear drive stiffness

“…Wang et al (2020) proposed differential feed system that can suppress the effect of motor torque harmonics on speed fluctuation of the table and improve speed smoothness at low-speed operation. Liu (2020) quantitative analysis of influence of structural stiffness on the vibration characteristics of the machine feed system. Zhang et al (2019) pointed out when the preload increases, bearing stiffness presents a nonlinear increasing trend and affects natural frequency.…”

Research on the Degradation of the Axial Natural Frequency of the Double-Nut Ball Screw Feed Drive System

“…位置对系统固有频率的影响；WANG 等 [4] 建立了 一个多自由度的非线性动力学模型，研究了不同 螺母位置、不同几何参数下，进给系统承受不同 激励力时的响应情况；LIU 等 [5] 建立了进给系统 的九自由度动力学模型，推导了进给系统沿轴向 与侧向的恢复力函数，研究了激振幅值对进给系 统轴向振动的影响；WANG 等 [6] 基于建立的动力 学方程，设计出了一种带调谐质量阻尼器的新型 结构丝杠，可以用于改善丝杠的时变振动特性； PISLARU 等 [7] 通过建立的混合动力学模型，更加 精确的分析了数控机床进给系统的固有频率以 及动态特性；ZHANG 等 [8] 研究了丝杠在不同预 拉伸量情况下丝杠螺母的接触变形关系，验证了 丝 杠 预 拉 伸 量 对 进 给 系 统 固 有 频 率 的 影 响 ； ZHANG 等 [9] 研究了进给系统固有频率随加速度 变化的情况 ， 得出加 速度 达到一 定值 后会使 系 统固有频率突变的结论； GU 等 [10] 建立了进给系 统的非线性动力学模型，研究了不同激振力、 工作台位置和系统质量等对动态特性的影响； LIU 等 [11] 通过建立的多自由度耦合动力学模型， 研究了多个因素对丝杠轴向与扭转固有频率的 影响；朱坚民等 [12] 基于建立的进给系统有限元模 型，通过计算各结合面接触刚度值，研究了结构 参数对进给系统固有频率的影响。由此可见，现 有关于滚珠丝杠副进给系统的研究多停留在固 有频率与进给系统几何或工作参数的关系建模 上，而对其因磨损导致的固有频率衰退现象的研 究较少。对于经历了长时间运转的滚珠丝杠进给 系统，丝杠、轴承等部件均会产生一定的磨损， CHEN 等 [13] 研究了进给系统滚动功能部件因运 行磨损导致的精度下降情况；ZHOU 等 [14] 研究了 一种基于磨损的新型预紧力衰退评价模型，并将 其应用于导轨预紧力预测；ZHOU 等 [15] 研究了滚 珠丝杠副预紧力因磨损产生的两阶段下降情况。 然而以上研究都并未介绍磨损对进给系统动态 特性的影响，实际上运行磨损还会使得对应部件 的刚度值降低 [16][17][18][19] ，进而导致进给系统固有频率…”