可控节流液体静压主轴回转精度提升的机理研究

Research on the Mechanism of Improving Hydrostatic Spindle Rotating Accuracy with Controllable Restrictor

可控节流技术可以显著提高液体静压主轴的刚度和回转精度,在工程上已得到实验证实,但是液体静压主轴在可控节流条件下是如何提高回转精度的过渡过程一直不明确。利用现有的液体静压主轴理论,还不能定量解释可控节流静压主轴从不平衡状态到平衡状态、以及稳态回转误差显著缩小的过渡过程。在考虑轴颈惯性力和非线性油膜力的基础上,根据可控节流器的工作原理和节流特性,建立了可控节流液体静压主轴动态轴心轨迹的理论模型,利用该模型进行数值模拟对过渡过程中的一系列物理现象做出了合理的定量解释。研究发现,在轴承结构参数和液压系统参数相同的条件下,可控节流主轴相比于固定节流可以显著缩短轴心轨迹的过渡过程响应时间、减小轴颈偏心位移、降低主轴稳态回转误差,从理论上揭示了可控节流器可以提高液体静压主轴油膜刚度和回转精度的物理机理。

Experiments have shown that a new controllable restrictor technology can significantly improve the stiffness and radial accuracy of hydrostatic spindles,but the transient process of the journal radial accuracy improvement is unrevealed.Since the existing theories can hardly explain the transient process of journal stabilization and radial error reduction,a novel numerical journal orbit model is developed on theories of journal inertial force,nonlinear oil film force,controllable restrictor principle,and restrictor parameters.By the new model,transient physical phenomenon during the journal stabilizing process can be numerically simulated and quantitively analyzed.The journals of controllable restrictor hydrostatic spindles and constant restrictor hydrostatic spindles are calculated,assuming they have the same hydrostatic journal bearing parameters and the same hydraulic system parameters.The results illustrate that controllable spindle could vastly reduce the orbit stabilizing time,the journal eccentricity,and the static radial error motion.Hence,the mechanism of the bearing oil film stiffness increment and radial accuracy improvement on the controllable restrictor hydrostatic spindles can be theoretically interpreted by the program.