基于Kriging预测模型的五轴机床动态特性场分析

Analysis of Dynamic Characteristic Field of Five‑Axis Machine Tool Based on Kriging Method

为了准确预测机床的加工空间动态特性,首先,建立双转台五轴机床不同加工空间的动力学模型和Kriging预测模型;其次,根据试验模态分析结果,修正了机床滑动结合面的刚度,分析了81个工作位置的机床模态;最后,选取机床动态特性变异函数,基于三维Kriging预测模型分析了双转台五轴机床不同加工空间的系统固有频率。结果表明:随着摆台摆角的变化,双转台五轴机床加工空间中的系统固有频率变化范围为46.2~52.9 Hz;当摆台摆角为0°时,系统固有频率最小;当摆台摆角为45°时,振动幅值最大;机床的加工空间动态特性预测能够为加工路径规划和刀具姿态选择提供技术支持。

During the machining process,the rigidity and natural frequency of the dual-turn-table five-axis ma⁃chine tool change with the variation of the tool space attitude and the space position of the machine tool compo⁃nents,affecting the machining surface accuracy of the workpiece.In order to accurately predict the dynamic char⁃acteristics,this paper establishes one dynamic model and another Kriging prediction model of the different ma⁃chining space of the dual-turntable five-axis machine tool.According to the measured modal analysis results,the stiffness of the machine tool sliding joint surface is corrected,and 81.The machine tool modalities of two work⁃ing positions are selected,and the dynamic characteristic variation function of the machine tool is finally select⁃ed.Based on the three-dimensional Kriging prediction model,the natural frequency of the system in different processing spaces of the dual-turntable five-axis machine tool is analyzed.Results illustrate that with the change of the swing angle of the pendulum,the variation range of the system natural frequency in the machining space of a dual-turntable five-axis machine tool is between 46.2 Hz and 52.9 Hz.The lowest natural frequency of the system corresponds to the pendulum angle of 0°and 45°.The vibration amplitude is the largest;the prediction of the dynamic characteristics of the machining space of the machine tool can provide technical support for machin⁃ing path planning and tool posture selection.