极端工况油垫可倾式静压推力轴承润滑机理与动压效应研究

Large vertical CNC processing equipments work under the extreme conditions such as high speed, heavy duty and micro clearance, the clearance oil film temperature of hydrostatic thrust bearing rise sharply, lubricating oil viscosity decline sharply, oil film grow thin quickly, together with bearing friction pair uneven deformation, local bearing friction pair appear boundary lubrication or dry friction, and then happen tribology failure. To solve the key problem, the tilting type static pressure oil pad is put forward to compensate hydrostatic bearing capacity by using dynamic pressure, and then improve the lubrication properties and tribology failure characteristics. Based on computational fluid dynamics and advanced lubrication theory, a lubrication performance model with coupling action between static pressure and dynamic pressure is established. With the help of discretization methods such as finite difference and finite volume, the effect of the supporting type, size and deformation of the pad, connection mode of the pad and the base on hydrostatic thrust bearing capacity, deformation, temperature, dynamic pressure and tribology failure synergy is studied through collaborative optimization design the static dynamic pressure, and experimental verification, and other means, and the general influence law is given, in order to solve the common problems of extreme conditions hydrostatic thrust bearing capacity shortage and tribology failure phenomenon occurred, and reveal the law of reasonable coordination of static pressure and dynamic pressure, and clarify its lubrication mechanism, thus to improve hydrostatic bearing capacity, rotational speed, rotating accuracy and stability, and reduce the tribology failure of China's large-scale high-speed heavy duty vertical CNC machining equipment.

大型立式数控加工装备在高速、重载和微间隙极端工况下，静压推力轴承间隙油膜温度骤升、润滑油粘度急剧下降、油膜迅速变薄、加之支承摩擦副变形不均匀、局部出现边界润滑或干摩擦，进而发生摩擦学失效。为攻克此关键难题，提出将静压油垫设计成可倾型式，利用动压补偿静压承载力不足，提高其润滑性能和抗摩擦学失效特性。依据计算流体动力学和先进润滑理论建立静动压耦合作用的润滑性能模型，借助有限差分和有限元体积等离散化方法，通过静动压协同优化设计，以及实验验证等手段，研究油垫支承型式、尺寸、变形及与底座连接方式对静压推力轴承承载力、变形、温度、动压和摩擦学失效的影响，并给出一般影响规律，揭示动、静压合理匹配规律，阐明其润滑机理，解决极端工况下静压推力轴承承载力不足和易发生摩擦学失效等共性问题，从而提高我国大型高速重载立式数控加工装备静压轴承承载能力、旋转速度、旋转精度和稳定性、以及降低摩擦学失效现象发生。

重载高速运转工况条件下，静压支承的高刚度、高稳定性要求间隙油膜极薄，在微间隙中润滑介质受到强剪切与挤压，达到了一种极端工况。在这种极端工况下，经典液体静压推力轴承设计原理和性能分析已不能正确反映真实的工作状况，常用的润滑理论亦不能解释这些现象。高速重载工况下油膜剪切发热和支承油膜压力增大，油膜变薄，局部形成边界润滑或干摩擦，进而经常出现摩擦学失效现象，并且旋转速度越高摩擦学失效的概率越大、周期也越短。因此，寻求改进极端工况条件下静压推力轴承的新手段和方法，对我国超大超重型立式车床等数控装备静压推力轴承承载能力和旋转速度提高、整机设计水平的提高，延长其寿命、降低故障发生及早预防，并扩大其应用范围均具有重要意义。.针对我国大型高速重载立式数控加工装备所使用的静压推力轴承在极端工况条件下迫切需要解决的承载力不足、摩擦学失效、高精度、稳定性等关键性难题，设计了新型油垫可倾式静压推力轴承结构，揭示了可倾式油垫的连接方式、支承型式及变形对轴承承载力、温升、油膜厚度、润滑介质流态等协同影响，找出了能改进其性能的可倾式油垫的连接方式、支承型式及变形，利用其所产生的动压力补偿了静压润滑性能的不足，为改进静压推力轴承的设计、高精度稳定运行和维护提供科学依据，以提高其工作效率，延长其使用寿命，扩大其应用范围。技术成果已在齐重数控装备股份有限公司所生产的3.5米及以上系列数控立式车床、立式磨齿机、数控滚齿机、双柱立式车铣床、单柱移动立式车铣床、双柱立式车削加工中心、立式铣车复合加工中心等产品上得到具体应用，静压回转工作台支承精度和稳定性进一步提高，旋转线速度提高近三倍，取得了良好的经济效益和社会效益。.发表相关论文16篇，其中SCI和EI收录10篇，北大中文核心期刊6篇，授权发明专利4项，授权实用新型专利8项。该项目执行期间获得黑龙江省科技进步奖二等奖和三等奖各1项。