织构化锥形水润滑电主轴轴承-转子系统耦合动力学特性研究

Motorized spindle with water-lubricated bearings is a new direction for future high-speed CNC machine due to its low frictional losses, pollution free and good damping. However, the low load capacity and stiffness due to the low viscosity of the water has limited the stiffness and the processing accuracy of the spindle. To solve the problem, a structure of conical water-lubricated motorized spindle with surface texture is proposed in this research. The following researches will be carried out according to the principle line of “the static performance of the bearing→the 5-DOF dynamic characteristics of the bearing→the rotordynamics of the spindle”: firstly, considering the turbulence, inertial flow, and cavitation appeared in the film of the high-speed, conical, water-lubricated bearing with surface texture, the mathematical model of static characteristics will be established to analyze the effect of surface texture on the static characteristics; secondly, a 5-DOF dynamic characteristics model for the conical water-lubricated bearing with surface texture will be established, aiming at investigating the influence of the surface texture on the dynamic characteristics; finally, a rotordynamic analysis model considering the 5-DOF dynamic characteristics of the conical water-lubricated bearing with surface texture for the flexible rotor system of the spindle will be proposed, in which the coupled rotor-bearing dynamic performance could be studied, and the influence of the surface texture on the dynamic performances of the water-lubricated spindle will be revealed. The expected results will provide theoretical basis for the precise design of the motorized spindle with water-lubricated bearings aimed at high speed, large load-capacity and high stiffness.

水润滑电主轴具有功耗低、无污染、阻尼特性好等优点，是高速数控机床行业的研究热点之一。然而水的低粘度特性导致了轴承的承载力与刚度低，制约主轴刚度的提高，影响机床加工精度。针对此问题，本项目提出织构化锥形水润滑电主轴结构，并以“轴承静态特性→5-DOF动态特性→主轴转子动力学”为主线，开展以下研究：针对高速织构化锥形水润滑轴承膜内的惯性、空化、紊流等复杂流动现象，建立静态特性数学模型，分析复杂流动现象下表面织构对轴承静态特性的影响机制；提出织构化锥形水润滑轴承5-DOF动态特性系数计算模型，阐明表面织构对轴承动态特性系数的影响规律；建立基于织构化锥形水润滑轴承5-DOF动态特性系数的主轴挠性转子动力学模型，研究轴承-转子耦合动力学特性，揭示表面织构对水润滑电主轴动力学特性的影响机制。项目成果可为高速、大承载、高刚度水润滑电主轴的精确设计奠定基础。

本项目针对水润滑轴承承载低、刚度小、制约主轴刚度等问题，提出了采用表面织构改善水润滑轴承润滑性能，开展了高速水润滑轴承润滑机理与表面织构对水润滑轴承-转子系统静动态特性影响的研究。项目的主要研究进展如下：1）建立了综合考虑水膜内紊流、空化、倾斜、热效应等流动状态下水润滑轴承五自由度静、动态特性数学模型，采用有限差分法求解，揭示了水膜流场压力分布、承载力、摩擦力和五自由度刚度、阻尼动态特性系数随运行参数的变化规律。2）提出了一种非对称阶梯槽织构化水润滑轴承结构，研究了非对称阶梯槽对轴承润滑特性的影响机制；基于空化模型、紊流模型，对微沟槽水润滑径向轴承进行三维CFD流场仿真研究及参数化设计，提出了可以显著提高水润滑轴承承载力的微沟槽结构参数及运行条件；建立了微沟槽锥形水润滑轴承静、动态特性数学模型。3）建立了轴承-转子系统动力学模型，提出了临界惯性矩及其计算公式，用以表征转子倾斜稳定性。4）最后设计并搭建了织构化水润滑轴承-转子实验台，实现了织构化水润滑轴承润滑特性多点多物理量实时同步测试，验证了数值模拟方法的准确性。上述研究为织构化水润滑轴承在高转速、大承载电主轴系统中的应用奠定了必要的理论与实验基础。已发表及接收论文6篇，其中SCI论文发表3篇、已接收SCI源刊论文1篇、EI论文发表2篇；参加国内国际会议6次；授权发明专利2项。本项目培养了研究生6人。