高速角接触球轴承油气润滑温升特性研究

油气润滑系统广泛应用于高速滚动轴承,油气润滑条件下轴承温升特性与温度场分布是影响轴承极限转速与动态工作稳定性的重要因素.基于高速滚动轴承摩擦学与两相流理论,以角接触球轴承为研究对象,建立了油气润滑条件下轴承与流体域之间的流固耦合模型.利用流体仿真软件Fluent对油气润滑条件下高速角接触球轴承与流体之间的传热方式及温度场分布进行了数值模拟分析,得到了轴承与轴承腔体的温度场分布.并进一步研究了供油量、润滑油粘度、轴承转速和载荷对轴承温升的影响,得到了油气润滑参数等与轴承温度场热平衡之间的关系.结果 表明:轴承转速与径向载荷是影响高速滚动轴承生热量与温升的主要因素,轴承内部温度场分布不均匀,对于特定工况存在最佳供油量与润滑油黏度使轴承温升最小.     

基于STAR-CCM+的高速角接触球轴承喷油润滑研究

喷油润滑系统广泛应用于高速滚动轴承,喷油润滑条件下轴承温升特性是影响轴承动态工作稳定性的重要因素。基于两相流理论,以71904C角接触球轴承为研究对象,建立全轴承模型,采用旋转坐标系描述各组件运动,分析滚动轴承在不同参数下喷油润滑的两相流与传热效率的影响规律。结果表明：随着轴承转速增加,轴承搅拌力矩也相应增加,导致轴承内部温度升高;润滑油运动黏度增加,轴承内部流场搅拌力矩增加,导致轴承温度升高;轴承喷油速度增加,内部流场温度呈现先增加后降低趋势,因此存在一个最佳喷油速度使得轴承温升最低。     

角接触球轴承的温度场分析

研究轴承的发热、传热过程,可为轴承动态油膜的热失稳研究提供理论支持。建立滚动轴承油气或油雾润滑下的热节点传热模型,利用热网络法建立温度场计算模型,并考虑轴承转速、载荷、离心力和自旋对温升的影响,计算出各节点的温度。结果表明,角接触球轴承的热生成与轴承转速、载荷、离心力和自旋有关,转速越高,载荷越大,则轴承的温升越高;随着转速增大,离心力和自旋对温升的影响增大,尤其高速情况下,离心力和自旋对轴承温升的影响不可忽略。     

机床主轴轴承热诱导预紧力自补偿方法

针对高速机床主轴轴承在主轴转速、负载及初始预紧力影响作用下,产生附加热诱导预紧力的问题,提出一种基于分离式隔圈的机床主轴轴承热诱导预紧力自补偿方法,实现了主轴轴承热诱导预紧力自补偿。首先,建立了主轴单元热结构耦合分析模型,分析了不同温度及载荷下,分离式隔圈的轴向相对位移;其次,利用高速机床主轴轴承试验平台研究了补偿前后不同主轴转速和初始预紧力下主轴单元振动和轴承温升的变化规律。结果表明,隔圈相对位移随温度成线性变化,而初始预紧力对其几乎没有影响;且采用分离式隔圈相较于传统的一体式隔圈,主轴单元振动略有增加,但轴承温升显著减小,说明所设计分离式隔圈能够有效降低热诱导预紧力。     

高速机床主轴轴承预紧力理论分析

预紧力的大小直接影响机床主轴动态特性,传统的定压预紧已不能满足现代高速化机床主轴的性能需要,预紧力可控成为主轴技术的重要发展方向.采用有限元法,完成了高速主轴系统温度场分析,给出了预紧力和轴承温升的对应关系,以推荐的轴承温升为控制目标,确定高速段轴承预紧力;以轴承的疲劳寿命为设计目标,获得低速段轴承预紧力.以某高速机床主轴为例,分析并计算了预紧力随转速变化的关系曲线,研究结果表明:高速机床主轴轴承预紧力理论分析方法可行,为机床主轴的预紧力控制提供了依据.     

高速电主轴热态特性仿真分析

在分析电主轴温度场理论的基础上,建立某高速磨床电主轴系统的有限元模型,计算了电主轴热特性分析的边界条件,利用有限元软件ANSYS Workbench分析其热态特性,得到了主轴系统的稳态温度场分布和热变形情况;同时分析计算了不同转速对主轴系统温升及热变形的影响.结果表明:主轴转速越高,相应主轴单元的温升变化及主轴热变形也越大.此分析为改善电主轴温度场分布及减小热变形提供了理论依据.     

高速精密主轴轴承热特性的计算及分析

轴承的发热变形是影响高速精密主轴系统刚度和加工精度的重要因素。本文采用节点网络法，对以电主轴轴承、主轴、轴承座为一体的系统建立了温度场计算模型，求出了系统各关键节点的温升情况，分析了转速、切削力、润滑方式等因素对节点温度的影响，得出了若干有意义的结论。     

高速角接触球轴承热特性和机械特性研究

基于动力学和摩擦生热理论,建立高速角接触球轴承热机完全耦合有限元模型,分析了滚动轴承的高速运动特性、温度分布、动刚度等,并与理论计算结果和试验结果对比.之后分析了轴承在不同转速下的温度和轴向变形,得到轴承在高速运行状态下的机械特性和热特性规律.分析结果表明:轴承内圈转速增大会导致各部件温度升高和轴承动刚度减小.另外,通...     

高速脂润滑滚动轴承密封结构优化与漏脂试验*

针对高速脂润滑滚动轴承密封过早失效的问题,建立油封的热-应力耦合有限元模型,研究油封主要参数和轴承工况参数对油封唇口的最高温度和最大接触应力的影响规律,对油封结构参数进行优化,利用强化温升漏脂试验台进行试验验证。结果表明：高速脂润滑滚动轴承油封密封性能的研究应该考虑温度的影响;唇口的最高温度随轴向过盈量、橡胶材料硬度、密封面摩擦因数、轴承转速和轴承腔内温度的增大而增大;最大接触应力随轴向过盈量和橡胶材料硬度的增大而增大,随密封面摩擦因数、轴承转速和轴承腔内温度的增大变化不大;密封结构优化后,平均漏脂率下降了56.7%,平均温升下降了54.3%。     

基于材料热特性的轴承预紧力自调节设计方法

采用滚动轴承支承的机床主轴在转速上升过程中摩擦发热产生温度变化,引起轴承预紧力变化限制了机床转速。提出材料热特性轴承预紧力自动调节方法,该方法是根据温度变化时金属材料受热伸长的特性,通过分析机床主轴转速上升时摩擦功率损耗产生的热量,建立主轴温度场模型。采用有限元计算主轴工作温升引起的热变形,按照两种金属材料受热伸长的差值,建立温差与位移关系的数学模型,并求解应用双金属材料结构设计参数。仿真计算结果表明,通过使用轴承预紧力自调节方法,可以有效地扩大机床转速范围,应用在加工中心的主轴上,主轴最高转速由2.5 kr/min 提高到了3 kr/min,取得了明显的效果。     

Thermal model of high-speed spindle units

For the purpose to facilitate development of high-speed spindle units (SUs) running on rolling bearings, we have developed a beam element model, algorithms, and software for computer analysis of thermal characteristics of SUs. The thermal model incorporates a model of heat generation in rolling bearings, a model of heat transfer from bearings, and models for estimation of temperature and temperature deformations of SU elements. We have carried out experimental test and made quantitative evaluation of the effect of operation conditions on friction and thermal characteristics of the SUs of grinding and turning machines of typical structures. It is found out that the operation conditions make stronger effect on SU temperatures when rpm increases. A comparison between the results of analysis and experiment proves their good mutual correspondence and allows us to recommend application of the models and software developed for design and research of high-speed SUs running on rolling bearings.     

The Performance of a Hybrid Ceramic Ball Bearing Under High Speed Conditions with the Under-Race Lubrication Method

Large bore (150 mm) hybrid ceramic ball bearings and all-M50 steel bearings were tested with under-race lubrication to compare the heat generation and the temperature rise at speeds up to 2.25 million DN. Furthermore, oil shut-off tests were carried out with both bearings over 2.25 million DN.

The experimental results of the heat generation for both bearings were nearly the same at an axial load of 19.6 kN. at 34.3 kN, the heat generation of the hybrid bearing was lower than that of the M50 steel bearing at low speed. The heat generation of both bearings gradually approached each other with increasing speed and became nearly equal at a speed of 15,000 rpm. The survivability of the hybrid bearing in the oil shut-off test was superior to that of the M50 bearing. These experimental results were explained by the calculation results using a computer analysis software which simulates the kinematics and the performance of ball bearings.     

THD Analysis of Rolling Piston and Journal Bearings in Rotary Compressors

A numerical analysis of the thermohydrodynamic lubrication of a rolling piston and two misaligned journal bearings in a rotary compressor has been carried out. The temperature rise of the oil film was calculated according to the transient energy equation of viscous fluid, and coupled analysis with the hydrodynamic lubrication of the rolling piston and journal bearings was conducted by using the finite element method and finite difference method. The distributions of the pressure and temperature rise of the oil film for several cycles were calculated. The analysis results show that for the journal bearings, the temperature of the oil film rises with the increase in pressure, the highest temperature appears around the region of the maximum pressure, whereas for the rolling piston bearing, there is a sharp peak in the temperature distribution. The maximum temperature in the oil film varies periodically with the rotation of the crankshaft, and after several cycles the balance between viscous heating and heat dissipation is achieved. The thermal analysis results were compared with those of the isothermal analysis. It is found that the difference in lubrication performance between the thermal and isothermal cases is relative small, due to the mild temperature rise in the bearing system.     

滚动轴承内部温度状态监测技术

在摩擦学和传热学理论的基础上,建立了滚动轴承温度场数值仿真模型,对轴承内部温度的分布进行了研究,获得了环境温度、工作载荷和润滑脂容积比变化时轴承温度的修正公式。并以轴承的振动和润滑脂温度为监测参数,建立了轴承状态监测系统。运用温度分布规律对测点温度进行了修正,有效地消除了环境温度、工作载荷以及润滑脂容量变化对报警准确性的影响。     

高速电主轴轴承热分析与实验研究

根据高速电主轴角接触球轴承中滚动体的运动情况,分析其受力状态,并考虑轴承预加载荷对滚动体在高速旋转状态下陀螺力矩的平衡效果,应用Palmgren经验公式计算轴承整体的摩擦热,然后依据传热学理论建立轴承的温升热模型,并用热网络法建立其热阻抗网络图,最后用120MD60Y6油雾润滑型电主轴的轴承进行试验验证.结果表明,轴承温升主要受转速、润滑油量、供气压力及载荷的影响,在主轴启动的初始阶段温升变化最快,且润滑油量和供气压力对轴承温升有一个最佳的适用范围.     

Thermal characteristics of a CNC feed system under varying operating conditions

In high-speed and high-precision feed systems, thermal positioning errors are mainly caused by the non-uniform temperature variations and resulting time-varying thermal deformations under different operating conditions. The research presented here ultimately aims to develop a generic method capable of evaluating the thermal characteristics (such as temperature rise of heat sources, thermal positioning error) of the feed system induced by varying operating conditions (feed speed, cutting load and preload of ball screw). The thermal contact resistance between the balls and the inner and outer rings of supporting bearing is calculated using the Hertzian theory and JHM method. Experiments were carried out on a high-speed feed system experimental bench, and the influences of operating conditions on temperature rises of supporting bearings and ball screw nut were analyzed. Based on a WNN-NARMAL2 model, the relationship between temperature rise of supporting bearings and operating conditions was established. Furthermore, with the temperature of the ball screw nut set to be a moving heat source load, the temperature and thermal deformation distributions of the ball screw were simulated. The work described lays a solid foundation for thermal error prediction and compensation of a feed system under varying operating conditions.     

基于热网络法的行星减速器温度场研究

通过对行星减速器中的齿轮、轴承等摩擦副的生热分析以及对减速箱整体的传热分析,借助热网络法,获得行星减速器工作过程中的温度场数据.分析热源与各节点热量的产生和传递关系,确定减速器中的最高温度及其所在位置,探索实际工作过程中由于温度上升、热栽荷集中而导致齿轮齿面、轴承中滚动体和滚道表面胶合的原因,揭示其发热机理,预测系统的...