精密车床主轴动态特性对系统稳定性的影响

Effect of spindle dynamics on system stability in super-precision machining center

根据精密车削中心切削细长零件的特点,利用系统动力学和线性稳定性理论,建立切削系统稳定性数学分析模型,明确了稳态切削区域与主轴转速和切削深度等切削参数的关系;根据这一数学模型,借助于稳定性耳图,进一步应用试验方法研究了精密车削中心主轴部件的动态特性对系统稳定性的影响.研究表明,随着工件悬臂长度增加,切削系统的稳态临界切深呈现下降的趋势,但并不是线性关系,在局部会出现稳态临界切深增加的情况.主轴夹紧力对系统稳定性的影响取决于系统刚度和阻尼的耦合变化,总的趋势是系统的刚度随着夹紧力增大而增加,但夹紧力增加会降低系统的阻尼,当阻尼的减少超过刚度的增加时,夹紧力增加将会降低系统的稳态切削深度.

The model of the system stability is developed for the machining of long slender parts in super-precision machining center. Based on this model, the effect of dynamic performance of the entire machining system, which is determined by the interrelated dynamics of spindle structure and workpiece, on the system stability is systematically investigated using impact testing techniques. The test results show that the general trend of the stable critical cutting depths is declined with the workpiece length increasing. But it is not a linear function. When the damping increment outweighs the stiffness declining, the stable critical cutting depth increases in some length range. The effect of spindle clamping force on system stability depends on the coupling change of stiffness and damping. Whether the higher clamping force is beneficial for system stability depends on whether the gain in stiffness is greater than the loss in damping.