直线导轨进给机构动态特性参数测试方法

Test Method of Dynamic Characteristic Parameters of Feeding Mechanism

依据机械阻抗原理,提出一种有限元计算与实验测试相结合的方法,确定带滚珠丝杠副的直线导轨进给机构的动态特性参数.把进给机构分为三个子结构建立其动力学模型,利用有限元谐响应方法计算单个部件上测点之间的频响函数;通过实验测定装配后的结构上测点之间的传递函数;应用频响函数识别法求解进给机构在三个方向上的刚度和阻尼参数.将识别出的刚度与阻尼值代入进给机构的有限元模型,计算所得模态频率和振型与模态实验所测结果一致,各阶固有频率的平均相对误差为2.43%.本方法既发挥了有限元方法计算单个零件动力学特性的准确性,又避免了实验测量单个大型零件频响函数的不便,具有良好的工程实用价值.

Based on principles of mechanical impedance,a new method which combines the finite element method with experimental tests is presented to determine the dynamic characteristic parameters of the feeding mechanism with the linear guideway and ball screw.Firstly,the feeding mechanism is divided into three sub-structures to establish its dynamic model,and the frequency response functions between the measured points on a single component are calculated by finite element method.Then the transfer functions after the assembly are determined by experimental testing.Finally,the identification of frequency response function is applied to compute the stiffness and damping in three directions.After taking the identified values of stiffness and damping into the finite element model,the natural frequency and mode shape from calculation are consistent with the results of the experiment,and the average relative error of each order natural frequency is 2.43%.This method exploits the advantage of accuracy using finite element method to calculate the dynamic characteristics of individual component and thereby avoids the inconvenience arising from experimental test.Thus,it has good practical value.