链传动啮合冲击理论分析及有限元模拟

Theoretical Analysis and Finite Element Simulation of the Meshing Impact of Roller Chain Drive

啮合冲击是引发链传动产生振动、噪声以及链条零部件发生疲劳损坏的主要原因,因此,精确地分析与计算啮合冲击载荷是进行轮齿强度计算以及链传动系统动力学研究的重要内容.为此,建立了链轮轮齿滚子间啮合冲击动力学模型,计算了啮合冲击力幅值;采用赫兹接触理论,对齿面接触应力进行了静态条件下的理论计算;建立了套筒滚子链传动系统有限元模型,采用三维弹性接触问题有限元分析方法,对轮齿滚子间的啮合冲击效应进行了精确模拟,分析了具有标准齿廓形状轮齿滚子瞬时啮合时,冲击载荷变化规律及应力分布情况.计算结果表明:在动态条件下轮齿滚子作为弹性体发生冲击接触时,接触区域变形并非理想的长方形区域;轮齿齿面的冲击接触力分布是不均匀的;在理论接触区域两侧冲击应力较大;在考虑了链轮齿形、间隙及弹性变形等多种影响因素的条件下,动态冲击载荷远大于静态条件下的理论计算值.

Meshing impact is the main reason for vibration,noise and fatigue damage of parts in chain drives.Therefore,accurate analysis and calculation of the meshing impact load are important both for tooth strength calculation and the research on dynamics of chain system.In this paper,the dynamic model of the meshing impact between sprocket tooth and roller has been developed and the amplitude of meshing impact force has been calculated.The theoretical contact stress on the tooth surface under static condition has been calculated using Hertz contact theory.The finite element model of roller chain drive system has been developed and the effect of meshing impact has been simulated accurately with finite element method for 3-D elastic contact problems.The variation of impact load and the distribution of stresses have been analyzed when instantaneous meshing effect occurs between roller and sprocket tooth with standard geometry.Calculation results show that the contact deformation under impact effect is not an ideal rectangular,when the tooth and roller are considered elastic bodies under dynamic condition.The distribution of impact force on the tooth surface is much uneven and the impact stresses on both sides of the theoretical contact region are greater.It is also observed that the dynamic impact load is much larger than the theoretical value under static condition when various factors such as the standard geometry of sprocket tooth,clearance and elastic deformation are taken into consideration.