Analysis of the machine tool dynamic characteristics in manufacturing space based on the generalized dynamic response model

摘要

Machine tool dynamic characteristics are seriously affected by the changes of the machining poses and the spindle bearing joints dynamic properties. As these changes contribute much more complexity and uncertainty for predicting the machine tool dynamic characteristics accurately, a new method is developed to research the changing regularity of the whole machine tool dynamic characteristics in generalized manufacturing space. In this method, the dynamic flexibilities at the spindle nose of x, y, and z directions in the focused frequency range are taken to represent the whole machine tool dynamic characteristics. The response surface method (RSM) and the orthogonal experiment design method are combined to establish the generalized dynamic response model, which contains the information of the spatial poses and the spindle bearing dynamic parameters. To establish this model, the simulations arranged by the orthogonal design are conducted by utilizing the dynamic model modified approach based on the validated finite element model (FEM) of the whole machine tool. With evaluating the fitting degree of this generalized dynamic response model, it can be used to predict the dynamic characteristics in the manufacturing space. Furthermore, an algorithm based on the established model is proposed to calculate the effect factors acting on the whole machine tool dynamic characteristics, which are caused by the changes of the spindle bearing dynamic parameters. The proposed analytical method has been applied in a three-axis vertical machining center to establish its generalized dynamic response model. The dynamic flexibilities at the spindle nose in the generalized manufacturing space are predicted, and they are validated by the dynamic experiments. With the calibrated model, effect factors of the spindle bearing joints are also obtained. All the predicted results support a theoretical basis on the optimal process routes planning, and the proposed analytical method can lay a foundation for further study on the dynamic information of the tool point.