滚动轴承最佳工作游隙的确定

滚动轴承工作过程中,轴承的热变形将改变轴承的工作游隙,使轴承实际工作性能背离设计者的设计思想,这里从理论上深入研究和分析了热变形对滚动轴承工作游隙的影响,并研究了装配应力及旋转速度对游隙变化的影响,研究成果可根据轴承的实际工作温度、旋转速度、装配应力,计算出合适的初始游隙,进而可以保证轴承在具体的工作条件下处于最佳的工作游隙状态.     

YKK500-2电机轴承工作游隙计算

滚动轴承工作过程中,由于热变形将引起轴承工作游隙的变化,使轴承实际工作在不合理的游隙区间。本文分析了热变形与滚动轴承工作游隙的关系,浅谈了装配预紧力及转速对游隙变化的影响。研究结论可用于指导轴承的使用者根据轴承的实际工作温度、转速、装配时应力大小,计算选择合适的初始游隙与轴承和轴的配合公差,从而保证轴承在长期稳定运行时处于合理的工作游隙。     

高温场对滚动轴承游隙的影响

建立了滚动轴承在高温热场中的保温筒有限元模型,运用ANSYS分析了其在高温场中的温度分布,并结合摩擦学和传热学理论分析其在高温场中的径向变形规律,计算其径向游隙减小量。结果表明:在高温场中,滚动轴承的径向游隙随环境温度的升高而减小,对游隙影响较大的是内圈沟道的变形,且300℃以后游隙减小量的变化趋向平缓。     

大型轧机滚动轴承延寿理论与方法研究

通过对轧机辊系机构的活动度分析。3维接触问题边界元解析、滚道热凸度分析和轴承座振动分析等。提出考虑结构弹性变形、热变形和运动副间隙时保证轧辊轴承内部均载的自适应均载原理和治烧延寿方法。本法在高刚度轧机滚动轴承治烧延寿实践中取得良好成效。     

高速加工中心电主轴热态特性研究

高速加工过程中,由电机生热及滚动轴承的摩擦生热而引起的电主轴的温升及热变形是影响加工中心精度的关键因素.对高速加工中心电主轴的热态特性进行了分析研究,详细论述了电主轴内部两大热源的生机理以及电主轴单元的传热机理最后总结并提出了改善电主轴单元热态特性的措施.     

基于混合编程的高速滚动轴承热分析软件的开发

高速滚动轴承的摩擦生热已成为影响其工作寿命和可靠性的重要因素。总结了计算机高级编程语言Visual Basic(简称VB)和FORTRAN以及有限元软件ANSYS的特点,结合3者各自的优点以及高速滚动轴承的热分析理论,采用混合编程的方法,开发了高速滚动轴承热分析软件,使用该软件能够方便地完成高速球轴承和高速圆柱滚子轴承的热分析,有效地预测轴承组件在复杂工况条件下的工作温度场。     

数控卧轴平面磨床砂轮主轴-轴承系统的热-结构耦合分析

以某型数控卧轴矩台平面磨床为研究对象,对其砂轮主轴-轴承系统进行了温度分布与热变形的有限元仿真。基于滚动轴承热态特性理论与传热学理论,利用ANSYS Workbench软件对主轴-轴承系统进行稳态和瞬态的温度场仿真,得到了轴承滚子与内外圈滚道温度随时间的变化规律;根据热-结构耦合分析理论和温度场仿真结果,对主轴-轴承系统进行了热-结构耦合分析,得到了主轴在径向、切向与轴向3个方向的热位移与热应力的变化规律,从而揭示了由轴承摩擦产生的热效应造成的温度升高与主轴产生热变形及热位移之间的关系。     

高速重载滚动轴承接触应力和变形的有限元分析

建立了高速重载滚动轴承接触应力和变形的三维分析模型,在对模型的边界条件进行合理假设的条件下,采用ANSYS软件对滚动轴承的接触应力和变形进行了分析计算,编制了参数化计算程序,方便、直观.地得出了轴承内、外圈以及滚动体不同部位的应力和变形.计算结果与赫兹理论解具有较好的一致性,表明模型的建立以及约束条件的设置准确、合理.计算结果为滚动轴承的设计和优化提供了依据,计算方法也便于工程应用.     

机械制造文摘

在刚性较高的精密机床上加工时,其加工误差主要是由于主面轴承和液压系统的温升,产生热变形所致。文中列举了许多精密机床(如坐标镗床、镗杆机等)的主轴热变形量及其对加工误差影响的实验数据;主轴的支承型式及轴承的精度等级不同,其热变形量也不一样。如:主轴支承采用A、C 级滚动轴承,空载时主轴受力端在水平方向的热变形量为3～5微米,若用(?)级轴承则为6～15微米,采用滑动轴承为18～30     

内装式电主轴电机的发热和温升问题

电主轴电机的功率损耗发热和高速滚动轴承的摩擦发热所产生的热变形严重影响了机床的加工精度,改善电主轴的温升和发热状况是当前电主轴研究的一大内容.就相关问题有针对性地提出了几种具体的处理措施.     

止推滑动轴承的温度场和热变形分析

通过对止推滑动轴承的传热学、摩擦学研究，建立了该轴承相应的稳态温度场和热变形的三维热分析有限元模型，并运用ANSYS分析了轴承处于热平衡状态时的温升和热变形。研究结果表明，对于井下用止推滑动轴承，由于其摩擦产生的热量很大，在地面常温下设计时应考虑到热变形对轴承间隙的影响。     

Study on thermal induced preload of ball bearing with temperature compensation based on state observer approach

The internal contact feature and thermal induced dynamic preload is essential for ball bearing, which is one of the key issues for thermal instability and stuck problems at high rotation speed. This paper presented a thermo-mechanical coupling model for angular contact ball bearing with preload and temperature compensation, for the purpose of dynamic preload monitoring. Based on the verified thermal balance equations, thermal deformation and thermal induced preload were achieved and feedback to the original local approach of heat generation calculation. Then, the nonlinearity and uncertainty heat transfer characteristic was considered via a state observer to verify the calculation process. The state variable of bearing’s temperature rise was defined and a state observer with proportional-integral term was designed. The difference between experimental data and calculation result was feedback by the observer to control the heat transfer and preload solving process. Thus, the real-time temperature rise, thermal deformation, and dynamic preload of bearing’s internal assemblies were obtained.     

A thermal analysis of strip-rolling in mixed-film lubrication with O/W emulsions

Increase of both roll and strip surface temperatures can significantly affect a rolling process, roll conditions and strip mechanical properties. A comprehensive thermal analysis in cold rolling, especially in a mixed film regime, is needed to understand how thermal fields develop in roll and strip during rolling. It requires a simultaneous solution of the mixed film model for friction in the roll bite and the thermal model for roll and strip thermal fields. This paper presents a numerical procedure to analyse strip rolling process using lubrication with oil-in-water (O/W) emulsions. The thermal model includes the effect of heat generation due to the strip deformation and frictional shear stress at the asperity contacts. The numerical analysis employs a coupled thermal model and a mixed film lubrication model for calculating the friction and the asperity deformation in the bite. The thermal model considers the initial temperatures of the roll and strip, temperature rise due to the strip plastic deformation and friction. While the O/W mixed-film lubrication model takes into account the effect of surface roughness and oil concentration (%vol) of the emulsion. The thermal effect is analysed in terms of strip surface temperature and roll temperature, which are influenced by rolling parameters such as reduction, rolling speed, oil concentration in the emulsion. The results of the parametric study indicate that the effect of oil concentration on the thermal field is relatively small compared to that of reduction ratio and rolling speed. The reduction ratio increases the maximum interface temperature in the roll bite. In the mixed film regime, rolling speed also increases the maximum interface temperature and alters the temperature field of the strip. The numerical procedure was validated against known experimental data and can readily be extended to hot rolling or used to analyse roll strip temperature subjected to different cooling system.     

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.     

高速角接触球轴承稳态温度场的数值模拟及实验研究

工程应用中,高速滚动轴承由于发热引起的失效严重影响设备的正常工作,因此研究轴承的温度场至关重要.以高速机床主轴上常用的B7010C/P4Y轴承为研究对象,用整体法分析轴承的生热量,使用热网络法建立轴承稳态温度计算模型,求解不同转速、载荷和润滑油温度下的轴承温度.结果表明:各节点温度与载荷和转速成正比,钢球节点处温度最高...     

大偏心下滑动轴承热弹流润滑状态及特性*

滑动轴承在大偏心条件下工作时，热效应及弹性变形使得油膜润滑状态发生变化，进而影响摩擦特性。为此建立耦合轴瓦弹性变形、轴颈轴瓦粗糙峰接触、油膜温度分布及黏温-黏压关系的滑动轴承混合润滑模型，采用有限差分法求解得到不同工况下油膜压力场、温度场分布，分析热效应及弹性变形对润滑状态转变及轴承各特性参数的影响；搭建实验台测量试件内表面温度分布，测试结果验证了计算模型的正确性。结果表明：大偏心时热效应和弹性变形使得油膜润滑状态出现转化；粗糙峰的接触使摩擦热增加，且在最小油膜处形成温度峰值；热效应和轴瓦弹性变形使得接触压力峰值集中在轴承两端，承载能力和摩擦力均有所下降。     

Thermal Error Compensation of the Wear-Depth Real-Time Detecting of Self-Lubricating Spherical Plain Bearings

The spherical plain bearing test bench is a necessary detecting equipment in the research process of self-lubricating spherical plain bearings. The varying environmental temperatures cause the thermal deformation of the wear-depth detecting system of bearing test benches and then affect the accuracy of the wear-depth detecting data. However, few researches about the spherical plain bearing test benches can be found with the implementation of the detecting error compensation. Based on the self-made modular spherical plain bearing test bench, two main causes of thermal errors, the friction heat of bearings and the environmental temperature variation, are analysed. The thermal errors caused by the friction heat of bearings are calculated, and the thermal deformation of the wear-depth detecting system caused by the varying environmental temperatures is detected. In view of the above results, the environmental temperature variation is the main cause of the two error factors. When the environmental temperatures rise is 10.3 °C, the thermal deformation is approximately 0.01 mm. In addition, the comprehensive compensating model of the thermal error of the wear-depth detecting system is built by multiple linear regression (MLR) and time series analysis. Compared with the detecting data of the thermal errors, the comprehensive compensating model has higher fitting precision, and the maximum residual is only 1 μm. A comprehensive compensating model of the thermal error of the wear-depth detecting system is proposed, which provides a theoretical basis for the improvement of the real-time wear-depth detecting precision of the spherical plain bearing test bench.     

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.     

计入热变形影响的内燃机主轴承热流体动力润滑分析

根据动载滑动轴承热流体动力润滑理论,结合热变形矩阵法,提出一种考虑热变形因素影响时的内燃机主轴承热流体动力润滑分析方法,阐述该方法的基本理论和控制方程,探讨热变形因素对主轴承工作时的轴心轨迹、润滑油流量、最大油膜压力和最小油膜厚度等状态参量的影响情况.结合一主轴承实例进行数值仿真分析,仿真分析结果发现,计入热变形影响因素后,同未考虑热变形影响时分析得到的结果相比,轴心运动轨迹发生了很大变化,平均润滑油流量和一个载荷周期内的最大油膜压力均明显增加,一个载荷周期内的最小油膜厚度明显减小,润滑油平均温升则稍有减小.内燃机主轴承在工作时受各种热源因素的影响会产生热变形,在主轴承设计以及内燃机润滑系统供油量设计过程中考虑这种变形因素的影响是很有必要的.     

Thermal reliability research on entire roller-embedded shapemeter roll

The reversible cold-strip flatness was detected by an entire roller-embedded shapemeter roll. During detection, the contact condition of the interference fit surface (between the top surface of the framework and the inner hole surface of the roll body) changes with increasing thermal deformation. This, in turn, affects the thermal reliability of the roll. Temperature field and thermal deformation models of the shapemeter roll were established based on heat transfer and thermal elasticity theory; the temperature difference, thermal displacement difference, and the interference fit value associated with the interference fit surfaces were derived from these models. A seven-pass cold reversible rolling process in a 1050 cold rolling mill was experimentally and theoretically analyzed. These analyses revealed that the temperature difference between the interference fit surfaces is largest (maximum value 20 °C) during the third rolling pass and normal functioning of the shapemeter roll is prevented. This occurred only in the third rolling pass. An optimal design model of the initial interference fit value was developed to ensure contact between the interference fit surfaces. The optimum results showed that an initial interference fit value of 0.06 mm yields a maximum temperature difference of only 5 °C in the third rolling pass. More importantly, the shapemeter roll functions normally and its thermal reliability is improved.