支撑地脚动态特性直接影响机床整机的动态特性,对地脚结合部进行参数辨识可以更准确地建立机床整机动力学模型。该文提出一种地脚结合部等效刚度和阻尼的辨识方法。将某床身试验台的地脚结合部等效为3向弹簧阻尼系统进行动力学建模,通过模态试验得到床身的模态频率与阻尼比,由此辨识出地脚结合部的等效刚度和阻尼。然而,该方法无法直接对任意支撑状态下的地脚等效参数进行辨识。针对这一问题,该文先对均匀质量床身对称支撑状态下的地脚结合部进行参数辨识,然后改变地脚所受正压力的大小,重复参数辨识过程,得出结合部参数与正压力的关系,用于计算任意承重状态下的地脚结合部参数。参数辨识结果表明,地脚结合部等效刚度和阻尼均随着正压力的增大而增大。通过有限元仿真对参数辨识结果进行了验证,考虑地脚参数的有限元模型仿真结果与试验结果一致。

The dynamic behavior of the support directly affects the dynamic behavior of a machine tool. Thus, the support joint parameters are needed for accurate dynamic models of machine tools. This paper presents a method to identify the equivalent stiffness and damping of support joints. A 3-D stiffness-damping model is used to replace the support joint of the machine tool bed in the dynamic model. The support joint parameters are identified by modal testing which shows the natural frequencies and the damping ratios of several vibration mode shapes of the machine tool bed. However, the method is unable to identify the joint parameters for all support states. To solve this problem, this model first identifies the joint parameters for a bed with a uniform mass in the symmetrical support state, and then repeats the modal testing as the normal force on the support joint is changed to relate the joint parameters to the normal force to identify the joint parameters for any support state. The results show that the stiffness and damping both increase with increasing normal force on the support joint. Finite element method (FEM) simulations are used to verify the parameters identification results with the FEM model for the support joint parameters consistent with the experimental results.