超声悬浮轴承径向承载特性分析及实验研究

发布时间：2018-05-09 13:37

本文选题：压电驱动 + 超声悬浮　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：非接触式悬浮支撑是高转速精密传动系统中重要的减摩途径。基于压电驱动的超声悬浮技术是一种能够有效降低摩擦并且易于控制的新型悬浮支撑技术。由于超声悬浮技术衍生出的超声悬浮轴承克服了传统非接触式悬浮支撑的局限,在高转速精密传动系统的非接触悬浮支撑领域优势显著。本文以高转速、低摩擦为目标,通过对悬浮承载特性进行理论建模和实验测试,对新型超声悬浮轴承的径向承载特性开展深入研究。开展非均匀气膜径向承载特性研究,分析不同悬浮位置处的非均匀挤压气膜的结构。基于非线性声学理论,从振动形式、平均能量和运动受力三个角度解释悬浮机理。基于流体动力学理论中的理想流体雷诺方程,采用数值分析的方法对二阶非线性抛物线型偏微分方程进行差分求解,计算非均匀气膜气压分布。分析压电换能器驱动特性参数、流场介质物流属性及辐射面轮廓结构对悬浮承载特性的影响,选取合适的压电换能器结构参数及超声悬浮轴承工况条件。从流体微元的平衡方程和运动方程出发,推导沿运动方向上的惯性项并对理想流体雷诺方程进行修正,考虑惯性效应对边界气膜处压力进行分析。建立服从正态分布规律的表面粗糙度随机分布函数,对非均匀气膜结构进行修正,基于平均流量模型重新推导同时考虑流体微元惯性、表面形貌及稀薄效应因素的悬浮力模型,分析修正后的压力流量因子随表面纹向系数和粗糙度标准差的变化规律及表面形貌对悬浮承载特性的影响。对高速回转工况下的气膜悬浮力模型和动态摩擦力矩进行修正,揭示回转转速对气膜悬浮承载特性影响。基于超声悬浮轴承的工作原理及对非均匀气膜悬浮承载特性的分析,研制超声悬浮轴承原理样机。结合梅森等效电路,建立了纵弯复合型压电换能器的声电等效网络模型。借助有限元法对压电换能器进行模态分析和谐响应分析。采用阻抗分析仪验证压电换能器声电等效网络模型的正确性,并依据阻抗模和相位角的测试结果对压电换能器进行阻抗匹配。搭建单换能器式和组合换能器式超声悬浮轴承测试系统,对超声悬浮轴承开展静态悬浮承载特性及回转工况下动态承载特性的测试实验,验证悬浮力理论模型的正确性和揭示回转转速对转子轴心轨迹及摩擦力矩的影响规律。
[Abstract]:Non-contact suspension support is an important way to reduce friction in high-speed precision transmission system. Ultrasonic suspension technology based on piezoelectric drive is a new type of suspension support technology which can effectively reduce friction and is easy to control. Because the ultrasonic suspension bearing derived from ultrasonic suspension technology overcomes the limitation of traditional non-contact suspension support, it has a significant advantage in the field of non-contact suspension support of high-speed precision transmission system. With the aim of high speed and low friction, the radial bearing characteristics of new ultrasonic suspension bearing are studied by theoretical modeling and experimental test. The radial bearing characteristics of non-uniform film are studied and the structure of non-uniform extrusion film at different suspension position is analyzed. Based on the theory of nonlinear acoustics, the suspension mechanism is explained from three angles: vibration form, average energy and moving force. Based on the Reynolds equation of ideal fluid in the theory of fluid dynamics, the second order nonlinear parabolic partial differential equation is solved by numerical analysis, and the gas pressure distribution of non-uniform film is calculated. The effects of driving characteristic parameters of piezoelectric transducer, flow field medium logistics properties and radiation profile on suspension bearing characteristics are analyzed. Appropriate piezoelectric transducer structure parameters and operating conditions of ultrasonic suspension bearing are selected. Based on the equilibrium equation and motion equation of fluid element, the inertial term along the direction of motion is derived, and the Reynolds equation of ideal fluid is modified, and the pressure at the boundary gas film is analyzed considering the inertial effect. The random distribution function of surface roughness is established, and the structure of non-uniform gas film is modified. Based on the average flow model, the suspension force model considering the inertia, surface morphology and rarefaction effect of fluid microelement is rededuced. The variation law of the modified pressure flow factor with the surface ripple coefficient and the roughness standard deviation and the influence of the surface morphology on the bearing characteristics of the suspension are analyzed. The film suspension force model and dynamic friction torque under high speed rotating condition were modified to reveal the influence of rotary speed on the bearing characteristics of film suspension. Based on the working principle of ultrasonic suspension bearing and the analysis of the bearing characteristics of non-uniform film suspension, a prototype of ultrasonic suspension bearing principle is developed. Combined with Mason equivalent circuit, the acoustoelectric equivalent network model of longitudinal bending composite piezoelectric transducer is established. Modal analysis and harmonic response analysis of piezoelectric transducer are carried out by means of finite element method. The acoustoelectric equivalent network model of piezoelectric transducer is verified by impedance analyzer, and the impedance matching of piezoelectric transducer is carried out according to the measurement results of impedance mode and phase angle. The testing system of ultrasonic suspension bearing with single transducer and combined transducer is built. The static and dynamic load bearing characteristics of ultrasonic suspension bearing are tested. The correctness of the suspension force model is verified and the influence of rotating speed on the axis trajectory and friction moment of rotor is revealed.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH133.3

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