【作者】 江桂云；

【导师】 张根保；

【作者基本信息】 重庆大学 ， 机械制造及其自动化， 2009， 博士

【摘要】 随着现代机械设备向大型化、高速、高精度、重载等方向发展,液体润滑动静压轴承得到越来越广泛的应用。动静压轴承在其静压油腔的进油路上采用节流器作为调节元件,节流器对动静压轴承的静、动态性能起着重要的作用。为了解决传统节流方式中固定节流器承载性能及油膜刚性差、可变节流器的动态特性较差等问题,本文创新性地提出了一种新型节流方式的动静压轴承——基于液压伺服控制的动静压轴承,该轴承采用液压伺服控制方式实现了节流方式由固定节流或可变节流到按需可控节流的转变。本文的研究成果及主要内容如下:①分析了液压伺服控制动静压轴承系统的组成及工作原理,建立了轴承力学性能的雷诺方程;采用有限差分法对不同节流方式下的静压、动静压轴承的静态性能进行了求解,采用MATLAB软件计算轴承油膜压力场;建立动静压轴承的静态性能解析法模型,实现了解析计算;采用FLUENT软件求解轴承的静态性能;对上述三种方法的求解进行了对比分析。实例证明,三种方法均能有效求解轴承的压力场及静态特性,三油腔动静压轴承和三油腔阶梯动静压轴承相比于四油腔静压轴承具有较高的承载能力和油膜刚性,液压伺服控制的动静压轴承具有较高的油膜刚性和承载能力。②建立了动静压轴承温度场的数学模型,对能量方程进行离散及迭代计算,分别采用数值计算法和流体力学分析软件FLUENT求解几种结构形式的动静压轴承的温度场分布。实例结果表明:两种方法计算出来的结果接近,比较符合实际运行工况。③阐述了动静压轴承油膜刚度和油膜阻尼形成的机理,提出了8个动力特性系数,探讨了动力特性系数的求解方法——有限差分法和作图解析法,有效地求解了不同节流方式下和不同腔形结构的静压、动静压轴承动力特性系数。实例结果表明:两种方法计算结果比较接近;三油腔阶梯动静压轴承具有较高的油膜刚度和阻尼系数,能大大提高轴承的运行性能。此外,还分析了轴承主轴在受到外界扰动时轴心运动轨迹的数学模型,推导了动载作用下主轴轴心轨迹的运动方程。实例计算表明:当主轴在恒定载荷作用下受到外界干扰时,在干扰消除后,轴心按一定轨迹回到原有初始平衡位置。④研究静压轴承节流机理,建立了毛细管、小孔、薄膜反馈、滑阀反馈节流方式下静压轴承的承载性能及油膜刚度解析式,并通过实验验证上述节流方式下轴承的承载能力及油膜刚性。提出了采用流量平衡方程法和线性化法推导上述四种节流方式下轴承的动态特性传递函数,得到动态特性方块图,实现动态仿真。仿真结果表明:固定节流方式下轴承的动态性能较好,而可变节流方式下轴承的动态响应速度偏慢、动态超调量偏大。⑤分析研究液压伺服控制动静压轴承的动态特性。首先从分析单自由度液压伺服控制的静压轴承入手,建立了相应的动态特性数学模型;其次,采用线性化法和动力特性系数相结合的方法推导两自由度液压伺服控制的动静压轴承动态特性方块图。在此基础上,探索前后径向轴承、主轴等多自由度交叉耦合的主轴转子系统动态特性传递函数的分析求解方法,实现了一系列的仿真分析。仿真结果表明:液压伺服控制的静压、动静压轴承具有较为理想的动态特性。本文开展的液压伺服控制动静压轴承设计理论中的研究方法和研究成果,对于开发适用于高速、高精度、重载等领域的新型动静压轴承提供了重要的参考及理论价值,是液体润滑轴承理论创新的一次探索,对于轴承设计理论将产生重要的推动作用。更多还原

【Abstract】 With the development of the modern mechanical equipment to large-scale, high speed, high precision, heavy load, etc. liquid lubrication hybrid bearings become more and more widely be used. On the entrance to hydrostatic oil recesses, the throttleers are used as regulate elements, and the throttleers play an important role in the static and dynamic performance of the hybrid bearings. For the bearing performance and the oil film rigidity of the fix throttleer are not very good and the dynamic characteristics of the variable throttleer is poor, The paper creatively puts forward to a kind of hybrid bearings with new type of throttle----based on the hydraulic servo control system. The hybrid bearing changes the way of fixed throttle and variable throttle to throttle by need. The main works and results are as follows:①By analyzing the composition and work principle of the hydraulic servo control system of the hybrid bearings, the Reynolds equation of the mechanical properties of the hybrid bearings were established. Finite difference method is adopted to solve the static performance of the hybrid bearings with different throttle ways and hydraulic servo control, MATLAB software was used to calculate the pressure field of the oil film. Analytical models for the static performance of the hybrid bearings were established to realize the analytic calculation. FLUENT software was applied to analyze and solve the static performance of the hybrid bearings. According to the comparative analysis of three methods above, all the methods can effectively solve the pressure field and static performance of the hybrid bearings, and compared with hydrostatic bearings with four oil recesses, the hybrid bearings with three oil recesses and the ladder hybrid bearings with three oil recesses have higher bearing capacity and oil film rigidity, and the hybrid bearing controlled by the hydraulic servo system has higher bearing capacity and oil film rigidity.②The mathematical model of the temperature field of the hybrid bearing was established, the energy equation was discreted and iterative calculated. Then the temperature field distribution of the several forms hybrid bearings respectively were calculated by numerical calculation and FLUENT. The examples show that the results of two methods are close to each other and agree with the actual operating conditions.③The formation mechanism of oil film rigidity and damping of hybrid bearing were analysed, and eight dynamic characteristics coefficients were put forward and the solving methods of the dynamic characteristics coefficients were discussed ---- finite difference method and drawing analytic method, and the coefficients of the hydrostatic bearings and the hybrid bearings were solved based on different throttle ways and different cavity shapes. The results of the two methods are close to each other, the ladder hybrid bearings with three oil recesses have higher oil film rigidity and damping coefficients and could greatly improve the performance of the bearings. Besides, the mathematical model of spindle axes locus with external disturbance was built, the movement equation of the spindle axes locus was derived when dynamic load was exerted to the spindle. Examples show that the axes will move when external disturbance is exerted to the constant load spindle, axes can come back to the original balance location after the disturbance was eliminated.④In order to deeply study the throttle mechanism of the hydrostatic bearing, the analytic equation of the bearing performance and the oil film rigidity for different throttle methods such as capillary, holes,film feedback, slide valve feedback throttle were established, and the bearing performance and oil film rigidity of the bearings with the throttle methods mentioned above were verified through experiment. According to the lack of study of dynamic performance of the bearings in different throttle ways, the dynamic transfer functions of the hydrostatic bearings throttled by throttle methods mentioned above were derived through the flow balance equations and the linearlization method, and the dynamic characteristics block diagrams were gained. The simulation results show that the dynamic characteristics of the hydrostatic bearing throttled by fixed throttle is better than variable throttle, the dynamic response of the hydrostatic bearings in variable throttle is slowly and the dynamic overshoot is large, which provided the important theory basic for the study of hydraulic servo control throttle method.⑤In order to generally analyze the dynamic characteristics of the hybrid bearings controlled by hydraulic servo system. Firstly, the mathematical models of the dynamic characteristics of the single degree of freedom hydraulic servo-controlled hydrostatic bearings were established. Seconedly, the dynamic characteristics block diagram for the two degrees of freedom hybrid bearing is derived by combinating the linear method with the method of dynamic characteristics of coefficients. lastly, the solution methods of the dynamic characteristics of spindle rotor system for several degrees of freedom cross-coupled such as radial bearings and spindles were quested, a series of simulation analysis were obtained. The simulation results show that the hydrostatic bearing and the hybrid bearing controled by hydraulic servo system have a more satisfactory dynamic characteristics.The study methods and the results of the new type throttle theory in the thesis provide important reference and theoretical value for the new hybrid bearings of the fields such as high speed and high precision, heavy load. It is a quest for the theory innovation of the liquid lubricant bearings, It will play an important role in the design theory of bearing.更多还原