高速电主轴用脂润滑轴承性能试验

以高速磨削电主轴用角接触陶瓷球轴承B7005C/HQ1P4为研究对象,分别在油雾润滑和脂润滑下对轴承进行高速性能试验,通过对比分析转速、载荷与温升的关系研究了脂润滑轴承的高速性能。结果表明,在循环水冷却的条件下,转速低于40 000 r/min或dmn值小于1.44×106mm.r/min时,高速电主轴可以使用脂润滑陶瓷球轴承。     

高速机床主轴用陶瓷球轴承动态性能试验分析

对高速磨床主轴用陶瓷球轴承B7005C／HQ1P4在不同转速、载荷及润滑条件下的运转特性进行试验，结果表明：电主轴在80000r／min的转速下仍能正常运转；在起始温度、转速、润滑及冷却相同的条件下，陶瓷球轴承较钢制轴承摩擦力矩小、温升低；在润滑不充分的情况下，陶瓷轴承具有良好的运转特性。     

电主轴用高速角接触陶瓷球轴承的开发

本文从轴承力学方面，分析了电主轴用陶瓷球轴承和钢球轴承的高速性能指标，如单位接触面积压力、刚度、旋滚比、摩擦力矩和功耗、比摩擦功。通过计算分析，得出了钢球轴承转速为６００００ｒ／ｍｉｎ的指标，与陶瓷球轴承转速为３０００ｒ／ｍｉｎ的指标相近。因此可安全地使用脂润滑的陶瓷球轴承代替传统用油雾润滑的钢球轴承。本研究具有明显的经济效益和社会效益，对我国今后开发陶瓷轴承提供了理论依据。     

全陶瓷球轴承油润滑特性及其对服役性能影响规律

相比于金属球轴承,全陶瓷球轴承在极端工况下的服役性能更加突出。为了揭示全陶瓷球轴承油润滑特性,提高全陶瓷球轴承的运转性能与使用寿命,以6208CE氮化硅全陶瓷深沟球轴承为例,对其在油润滑工况下所表现出的摩擦、振动、温升等特性进行试验研究,探讨供油量对全陶瓷球轴承润滑状态的影响,并对试验后的全陶瓷球轴承接触微区表层进行解析。研究发现：全陶瓷球轴承油润滑服役过程中,在某个特定工况下存在一个最佳供油量,使得轴承可实现全膜润滑,从而表现出最好的摩擦、振动、温升等特性;小于最佳供油量时,为乏油状态,轴承接触微区存在油-固混合润滑状态;大于最佳供油量时,过多润滑油液会产生的黏滞阻力;相比于载荷,轴承的转速对最佳供油量的取值具有决定性影响。研究成果对于揭示全陶瓷球轴承油润滑特性,丰富其润滑理论与方法具有一定指导意义。     

润滑油黏度对全陶瓷球轴承腔体温度场分布规律的影响

为揭示全陶瓷球轴承在油润滑条件下内部温度场分布及变化情况,提高全陶瓷球轴承的运转性能与使用寿命,以7007C氮化硅全陶瓷角接触球轴承为研究对象,利用仿真软件模拟分析不同工况和润滑油黏度条件下全陶瓷球轴承腔体内部温度场及润滑油的分布状态;在轴承寿命试验机上进行相同条件下全陶瓷球轴承的动态特性试验,研究在油润滑工况下全陶瓷球轴承的温升特性。结果表明：随着轴承转速的提高,全陶瓷球轴承腔体内温度呈增大趋势,腔体内润滑油体积分数呈减小趋势;更换不同黏度润滑油发现随着润滑油黏度的增大,全陶瓷球轴承腔体内温度场呈现先减小后增大的趋势,存在最优黏度值使全陶瓷球轴承腔体温度达到最小值,轴承服役性能表现最佳。研究成果为实际生产中全陶瓷球轴承最优润滑油的选择提供了技术参考。     

基于电容法的脂润滑球轴承弹流膜厚影响因素研究*

采用电容法对脂润滑球轴承的弹流膜厚影响机制进行了研究，分别在不同轴承转速、轴向载荷、润滑脂类型以及滚珠数量条件下对弹流膜厚值进行测量。结果表明：轴承转速的提升会导致温度的变化，虽然不同润滑脂具有不同的剪切稳定性，但所有润滑脂的标准化膜厚值变小，即导致更恶劣的乏油程度；载荷的变化仅对剪切稳定性低的润滑脂的弹流膜厚值有影响；而轴承滚珠数量减半后，在每个滚珠所受载荷不变的情况下，润滑脂所受剪切作用减少，导致轴承的乏油程度更加严重。研究表明，脂润滑球轴承的弹流膜厚值受到多因素的影响，需要对不同情况进行单独分析。     

微小卫星用陶瓷轴承脂润滑姿控飞轮的性能试验

为解决微小卫星姿态控制执行元件—姿控飞轮的轻量化、高效支撑及润滑问题,提出了应用脂润滑陶瓷轴承为微小卫星姿控飞轮提供支撑和润滑的方法。试验研究了陶瓷轴承脂润滑姿控飞轮的启动、摩擦功耗、温度特性、抗振动性能及寿命特性,试验结果显示:与同型号钢制球轴承相比,陶瓷球轴承在静态摩擦力矩及功耗方面性能更优良,可以有效减小姿控飞轮的启动电流和摩擦功耗。陶瓷轴承脂润滑姿控飞轮在-30～50℃具有良好的启动性能,低于卫星最低工作温度20℃时仍能保持良好的启动特性,无冷焊问题,完全满足卫星发射时抵抗振动的要求。振动试验后的姿控飞轮在4年的地面真空试验中功耗电流变化率在有真空度和温度变化的影响下小于1%,验证了陶瓷轴承脂润滑姿控飞轮使用寿命优于4年,满足国内微小卫星对姿控飞轮轻量化和使用寿命的要求。     

关于陶瓷球轴承应用的试验研究

陶瓷球轴承具有良好的机械性能和热性能,但由于试验验证不充分等因素,使得其在国内航空发动机上的应用还处于起步阶段。通过开展转速试验、润滑试验、加减速试验和断油试验,来验证钢球轴承与陶瓷球轴承在不同工况下的工作性能,对比分析试验过程中两种轴承的外圈温度和轴承座振动变化情况,得出陶瓷球轴承在航空发动机工况下各项工作性能均优于钢球轴承的结果。     

混合式陶瓷轴承沟道结构参数的简化算法

以目前钢轴承的结构参数合理正确和轴承滚动体与内外圈滚道在相同的接触应力及接触面积作用下具有相近的接触疲劳寿命及发热为前提 ,以相同负荷作用下 ,混合式陶瓷球轴承与相应钢轴承的接触应力和接触面积相等为依据 ,给出了混合式陶瓷球轴承内外圈沟道结构参数的简化计算方法。以 6 2 0 9深沟球轴承为例 ,对相应的混合式陶瓷球轴承的沟道曲率半径进行了计算 ,以计算结果制造的混合式陶瓷球轴承的运转性能完全能够满足使用要求     

润滑脂对轴承噪声影响因素探讨

引起轴承噪声的原因很多,主要来自轴承本身,如材质、设计制造、加工精度、内外圈及滚动体的表面形貌和装配等,其次来自所选用的润滑剂。目前,80以上的轴承采用润滑脂润滑,因此,研究润滑脂对轴承噪声的影响,开发密封轴承专用的低噪声润滑脂是非常必要的。1　试验1.1　润滑脂在大多数密封轴承的润滑中12-羟基硬脂酸锂基脂应用最广。因此,本试验采用12-羟基硬脂酸锂基润滑脂,其基础油采用天然矿物油、合成烃油和酯类油,添加剂采用抗氧剂和防锈剂。1.2　试验轴承国产单列深沟密封球轴承,型号为6200、6204、6206和6308。1.3　噪声的测试轴承的…     

涡轮增压器高速混合陶瓷球轴承发热及其效率研究

建立了高速混合陶瓷球轴承和滑动轴承的发热计算模型,对发热量进行计算,分析了混合陶瓷球轴承发热的影响因素.对使用混合陶瓷球轴承和滑动轴承的涡轮增压器总效率进行对比试验,结果表明,使用混合陶瓷球轴承的涡轮增压器的总效率和极限转速均有显著提高.     

卫星姿态控制飞轮轴承不同润滑状态下功耗分析

为了满足卫星姿态控制飞轮低功耗、小波纹力矩、长寿命的要求，对不同液体润滑剂润滑条件下飞轮轴承的功耗、温升变化，以及润滑脂润滑条件下不同脂用量对稳速时温升及挥发损失的影响进行了分析。实验结果表明：减少润滑剂的用量功耗和温升都小于润滑剂正常用量时；减少润滑脂的用量轴承润滑功耗更加稳定，但温升较大；高速下要考虑轴和轴承座的散热问题，以降低热平衡温度；润滑剂用量的减少导致挥发率变大，挥发寿命很短，但在真空、密闭环境中其挥发是相当小的，减少润滑剂用量是可行的。     

Friction torque in grease lubricated thrust ball bearings

Thrust ball bearings lubricated with several different greases were tested on a modified Four-Ball Machine, where the Four-Ball arrangement was replaced by a bearing assembly. The friction torque and operating temperatures in a thrust ball bearing were measured during the tests. At the end of each test a grease sample was analyzed through ferrographic techniques in order to quantify and evaluate bearing wear.A rolling bearing friction torque model was used and the coefficient of friction in full film lubrication was determined for each grease, depending on the operating conditions.The experimental results obtained showed that grease formulation had a very significant influence on friction torque and operating temperature. The friction torque depends on the viscosity of the grease base oil, on its nature (mineral, ester, PAO, etc.), on the coefficient of friction in full film conditions, but also on the interaction between grease thickener and base oil, which affected contact replenishment and contact starvation, and thus influenced the friction torque.     

Prediction of the friction torque in grease lubricated angular contact ball bearings using grey system theory

The development of special grease makes it possible for angular contact ball bearings to operate at high speed and temperature; however, as an important performance parameter, friction torque of bearings lubricated with grease is much greater than that of bearings lubricated with oil-air, and heat generation due to frictional loss is also greater, so it is necessary to predict the friction torque occurring in grease lubricated angular contact ball bearings. Based on grey system theory, a new prediction methodology for bearing friction torque is proposed which capitalizes on the notion that the information about friction torque of angular contact ball bearing is generally poor, incomplete and uncertain. A grey prediction model, GM (1, N) model, is presented to predict the friction torque in grease lubricated angular contact ball bearings. Several experiments on the friction torque of grease lubricated angular contact ball bearings were conducted to model and validate the effectiveness of the GM (1, N) model through on-line and off-line approaches. Experimental results show that about 90% of bearing friction torque under varying speed can be predicted in the on-line prediction; above 85% of bearing friction torque under varying speed and different loads can be predicted in the off-line prediction. Comprehensive analysis shows that, the GM (1, N) model performs very well for both modeling data and model validation data under different loads, varying bearing speed and work cycles, the proposed methodology can be used to predict bearing friction torque with good accuracy and robustness.

     

Frictional power loss in solid‐grease‐lubricated needle roller bearing

The use of solid grease as a lubricant, in comparison with standard grease or oil, is a pre‐requisite when needle roller bearings undergo a high‐speed oscillating motion and when access to the bearing is difficult for maintenance purposes. This paper examines the frictional power loss of a solid‐grease‐lubricated needle roller bearing. First set of measurement result reveals that the test bearing has higher frictional power loss as compared with other bearings with conventional lubrications, due to the high viscosity of the solid grease. Furthermore, measurements are compared with the Palmgren and SKF models. For improving these models, the parameters of the models are updated on the basis of the measurement data. A second set of measurement result shows that the use of oil (kept at higher temperature) in addition to solid grease significantly reduces the frictional power loss. The reduction is due to the decrease in operational viscosity of the solid grease. Copyright © 2012 John Wiley & Sons, Ltd.     

Grease Lubrication of Ultra-High Speed Rolling Contact Bearings

The failure mechanisms of grease lubricated ball bearings operating in the DN range from 1.0 × 10⁶ to 2.0 × 10⁶ was studied. A new rig capable of controlled operation of 20 and 25 mm ball bearings at speeds up to 100,000 rpm is described. Ball separator design seems to be a very important factor and a lightweight single piece machines outer ring controlled ball separator appeared to give the best results. In general, mechanical factors such as vibration, bearing design, bearing fit and tolerances, dynamic balance, load alignment, etc., have more influence on the performance of the bearings studied than gross grease variables. Under ideal conditions it is indicated that adequate lubrication with grease is possible for periods over 100 hours. However, under the test conditions generally in existence in the ultra high speed rigs grease lubrication was only adequate for very short periods.

Grease compositional factors leading to better performance are smooth texture and hard consistency. At the temperature investigated diester type oil was slightly superior to mineral oil and greatly superior to silicone oil.     

Temperature rise of double-row tapered roller bearings analyzed with the thermal network method

Based on generalized Ohm׳s law, the thermal network model (TNM) is developed for double-row tapered roller bearing lubricated with grease, which is commonly used in high-speed railway. The load distribution and kinematic parameters in bearing are obtained by developing a quasi-static model. The temperature of bearing at different speeds, filling grease ratios and roller large end radius are investigated. The results show that large rotating speed and filling grease ratio result in high temperature rise, especially at roller large end/flange contacts. Besides, an optimal roller large end radius is presented and its mechanism has been explored.