Experimental Investigation on the Bush Inner Surface Temperature of a High Speed Spiral Oil Wedge Sleeve Bearing

The temperature of bush inner surface temperature is measured by using infrared thermometer and transparent bearing,and temperature rise is measured by using thermocouple. The influence of rotating speed and axial location on the bush inner surface temperature is studied,and the influence of supply pressure and rotating speed on the temperature rise is analyzed. The results show the bush inner surface temperature and temperature rise of spiral oil wedge hydrodynamic bearing increase with the increase of rotation speed. In axial direction,the temperature is higher around the oil return hole. The temperature rise decreases with the increase of supply pressure. The highest temperature of bush inner surface and temperature rise are higher at higher speed,so the temperature rise is the fundamental reason which restricts the increase of rotation speed for high speed sleeve bearing.

A Study of High-Temperature and High-Pressure Experiment of Correlativity between Deformational System of Au-Bearing Rocks and Element Adjustment

Modelling of migration and accumulation of elements Au and Ag in rocks under temperatures of 350–450°C and a confining pressure of 300 MPa and axial pressure of 100–150 MPa is conducted. It is found that the contents of gold and silver get higher in metallic sulphides such as pyrite, chalcopyrite and sphalerite as well as in quartz and muscovite, and get lower in chlorite, biotite, seriate, albite and calcite, showing that tectono-dynamics is one of the important factors for petrogenesis and metallogenesis.

Comparative Studies on Low Noise Greases Operating under High Temperature Oxidation Conditions

Oxidation induction time(OIT) testing by differential scanning calorimetry(DSC) was used to evaluate the oxidation resistance of lubricating greases. Under the high temperature condition, bearing noise was detected when grease passed the initial stable stage of oxidation. The chemical and physical structure of grease samples before and after high temperature oxidation were also analyzed by FT-IR spectrometry and scanning electron microscopy(SEM), then the effects of oxidation at high temperature on bearing noise were investigated. It is found out that for lithium greases, oxidation of base oil and thickener is the main reason responsible for the increasing bearing noise. As regards the polyurea greases, the change of fiber microstructure at high temperature is the main reason for the increasing bearing noise.

Modeling of Rolling Contact Friction of Ball Bearings at Elevated Temperature

In order to predict the rolling friction coefficient and analyze the effects of material compatibility on the friction coefficient at elevated temperature(from room temperature to 600℃),a theoretic computation model was developed based on bearing's elastic contact hysteresis and related material characteristic parameters.Some examples were carried out to verify the feasibility of the model.The research results show that the material compatibility has significant effects on rolling friction coefficient,especially the modulus of elasticity and the expansion coefficient of material,and results also show the rolling friction coefficient of the matched pair between GCr15 and Si3N4 is the smallest comparing with that between GCr15 and M50(or ASP-23,or GCr15) when making GCr15,M50,ASP-23,and Si3N4 materials as bearing's rolling balls and GCr15 material as bearing's inner and outer rings.Further research indicates that the working temperature also has played an important role in the rolling friction coefficient of the ball bearing,moreover,the friction coefficient of the matched pair of M50 and Si3N4 behaves most stably at elevated temperature.

Infuence of Mg on Thermoplasticity of High-Temperature Stainless Bearing Steel Cr_(14)Mo_4

Through the addition of appropriate amount of Mg （0.01-0.01 5 wt%） to the stainless bearing steel Cr14Mo4, the high-temperature thermoplasticity of steel was improved. The mechanism has been uncovered that the added Mg plays an important role in refining and uniforming the carbide precipitations in the steel. It has been found that the segregation of trace Mg is the key to improve the dispersed carbide. Moreover, considerable segregation of Mg in steel during annealing was evidenced by the theoretic analysis.

M50高温轴承钢表面TiN涂层与镀银层对磨的摩擦特性

以航空发动机主轴轴承引导面与保持架之间的异常磨损为背景,研究了M50钢及M50钢表面沉积Ti N涂层与保持架材料镀银层之间对磨时的摩擦特性,分析了干摩擦条件下相对滑动速度、接触应力及其交互作用对摩擦系数随时间变化的影响规律。采用SEM观察了摩擦表面的形貌,并用EDS对表面成分进行了分析。结果表明,摩擦系数随时间逐渐增大,存在明显的转变点;在低滑动速度和较低接触应力时,摩擦系数可以长时间维持在0.15~0.25较低水平,在较高滑动速度和较高接触应力时,摩擦系数很快上升到0.5左右,在试验选择的参数范围内,该转变时间与接触应力P和滑动速度V的乘积PV值基本上呈线性关系;高速大接触应力摩擦时,M50钢表面会受到硬质颗粒的作用产生划伤,而Ti N涂层对M50钢具有良好的防护作用,可以明显延缓高摩擦系数出现的时间,阻止M50钢中碳化物脱落,防止表面磨损。

高速精密角接触陶瓷球轴承设计及试验研究

针对某数控机床主轴轴承低极限转速及低DN值(轴承内径和轴承转速的乘积)的问题,为解决机床主轴轴承高极限转速的问题,满足高DN值、高极限转速及精度P4级的要求,设计开发了一款高速电主轴精密角接触陶瓷球轴承,并进行了轴承温升和振动试验。首先,根据轴承的使用环境选取了角接触陶瓷球轴承主参数,并为降低高转速下轴承发热量选取了合适的轴承材料;然后,利用建立的角接触球轴承动力学模型并联立动力学微分方程进行了求解,以摩擦力矩为目标函数对轴承球径和内外沟曲率半径系数进行了正交优化选取,还进行了动力学和疲劳寿命分析;最后,开展了角接触陶瓷球轴承的极限转速试验,进行了温升和振动分析,验证了该轴承温升和振动指标满足设计要求。研究结果表明:优化后得到轴承的球径D w为6.35 mm、内沟曲率半径系数f i为0.55、外沟曲率半径系数f e为0.52;计算优化后角接触陶瓷球轴承的最大接触应力不超过2100 MPa,滚动体与保持架的最大作用力不超过3 N,保持架受到的等效应力及极限转速下轴承疲劳寿命为84.5 h左右,均满足设计使用要求;且优化后的角接触陶瓷球轴承最小摩擦力矩为102.0331 N·mm;优化后轴承的最高温度为56℃,振动加速度不高于19.6 m/s^(2)。该轴承满足超精密数控机床高速电主轴的应用需求,同时提高了国内现有高速电主轴的极限转速。

劣化润滑脂对新能源汽车电机轴承性能的影响

为研究不同劣化时期润滑脂对新能源汽车电机轴承性能的影响,并选取合适的润滑脂,采用试验的方法,研究了两种候选润滑脂及其对轴承性能的影响。首先,采用静态热劣化法获得了21组不同劣化时期的润滑脂样品,并分析了润滑脂样品的锥入度、分油率等特性变化;然后,在考虑轴承工况的基础上,利用高速轴承漏脂温升性能试验机等设备试验研究了不同劣化时间润滑脂对轴承漏脂、温升、振动和噪音等性能的影响;最后,综合分析了润滑脂的劣化及其对轴承性能的影响,为新能源汽车电机轴承选择了合适的润滑脂。研究结果表明:A型润滑脂的性能更稳定,其非工作锥入度变化率为32.53%,分油率在0~0.053%范围内波动,其特性变化均小于B型润滑脂;两种劣化润滑脂均导致轴承外圈温度升高、轴承振动速度和噪音增大,但B型润滑脂对轴承振动速度和噪音的影响较大,其部分高频增加900%、噪音升高27%。因此,综合考虑润滑脂的分油率、锥入度,以及润滑脂对轴承温升、振动和噪音等使用性能的影响,推荐A型润滑脂为新能源汽车电机轴承润滑介质。该研究结果对新能源汽车电机轴承润滑介质的选择具有较为重要指导意义。

冻融和高温作用下CFRP布粘贴页岩砖黏结性能变化

为研究冻融和高温作用下碳纤维增强塑料布(carbon fiber reinforced plastic sheet,简称CFRP布)粘贴页岩砖黏结性能的变化规律,对冻融环境、高温(60℃)环境、冻融和高温环境循环作用下,页岩砖、CFRP布和环氧树脂胶的材料性能进行测试,并对CFRP布粘贴页岩砖单面剪切性能的变化规律进行试验研究。结果表明:页岩砖、CFRP布和环氧树脂在冻融和高温循环作用下的材料性能受到较大影响,经历3次大循环作用后,页岩砖的抗压强度降低了31.62%,CFRP布的抗拉强度和弹性模量分别下降了44.38%和42.28%,环氧树脂的抗拉强度和弹性模量分别下降了32.45%和35.36%;冻融和高温循环作用对CFRP布粘贴页岩砖的单面剪切性能影响最明显,其次是单独冻融循环作用的影响,单独高温的影响最小。给出不同侵蚀环境下CFRP布粘贴页岩砖的单面剪切承载力计算公式,可以准确地计算不同环境下CFRP布粘贴页岩砖的单面剪切承载力。

Comparison of microstructure and property of high chromium bearing steel with and without nitrogen addition

Microstructure and property of bearing steel with and without nitrogen addition were investigated by microstructural observation and hardness measurement after different heat treatment processing. Based on the microstructural observation of both 9Cr18 steel and X90N steel, it was found that nitrogen addition could effectively reduce the amount and size of coarse carbides and also refine the original austenite grain size. Due to addition of nitrogen, more austenite phase was found in X90N steel than in 9Cr18 steel. The retained austenite of X90N steel after quenching at 1050℃ could be reduced from about 60% to about 7 9% by cold treatment at -73℃ and subsequent tempering, and thus finally increased the hardness up to 60 HRC after low temperature tempering and to 63 HRC after high temperature tempering. Furthermore, both the wear and corrosion resistance of X90N steel were found much more superior than those of 9Cr18 steel, which was attributed to the addition of nitrogen. It was proposed at last that nitrogen alloying into the high chromium bearing steel was a promising way not only to refine the size of both carbides and austenite, but also to achieve high hardness, high wear property and improved corrosion resistance of the stainless bearing steel.

电磁冲击处理对M50轴承钢显微组织与强韧性的影响

建立了电-磁-热多场耦合的电磁冲击仿真模型,利用该模型预测了电磁冲击过程中试样表面的温度变化过程,分析了电磁冲击处理对材料强韧性的影响,并利用扫描电子显微镜(SEM)和电子背散射衍射(EBSD)对材料内部微观结构和断口形貌进行了表征和分析。结果表明:该模型成功预测了电磁冲击过程中试样表面的温度变化过程,且预测值与测量值吻合良好;合适的电磁冲击处理工艺(EST2)可以使材料具有较好的综合力学性能且有效提高材料性能的一致性,在保持平均抗拉强度基本不变的前提下,试样的断后伸长率提高了17.2%,冲击韧性提高了5.5%,屈服强度和抗拉强度一致性分别提高了52.8%和59.9%,冲击韧性一致性提高了42.6%。

高温磁悬浮轴承-转子系统建模与动力学分析

在多电航空发动机中,主动磁悬浮轴承因其耐高温、非接触等特性可以突破温度对支承部位的限制,使支承部位能够更靠近燃烧室.为探究温度对磁悬浮轴承转子系统动态特性的影响规律,提出一种高温磁悬浮轴承转子系统动力学建模方法.通过仿真得到转子在不同温度下的温度分布,并使用多项式拟合转子轴向温度分布;基于有限元方法推导柔性转子单元的动力学模型,引入温度影响,建立考虑温度影响的磁悬浮轴承转子系统整体动力学模型,并通过模态试验验证模型的准确性;基于理论动力学模型分析系统的动态特性.结果表明:温度升高会导致转子的前三阶支承模态频率下降,增大各阶幅频响应幅值;当温度从常温升至450℃时,转子的前三阶弯曲支承模态频率分别降低了3.818%、5.670%、3.183%,前三阶弯曲模态幅频响应幅值分别升高了83.4%、34.4%、24.1%.

大尺寸均质化M50轴承钢坯的构筑成形

针对大尺寸M50轴承钢锭中液析碳化物粗大的问题,提出采用金属构筑成形技术制备大尺寸均质化M50轴承钢坯的新思路。通过基元加工、真空封焊、高温变形、保温扩散和多向锻造工艺制备了80 mm×80 mm×1000 mm的M50轴承钢构筑坯料。拉伸和疲劳性能的试验结果表明,M50轴承钢构筑界面实现了完全冶金结合,其力学性能达到与基体相当的水平,通过构筑成形技术制备的均质化M50轴承钢坯的疲劳性能显著优于采用一体化冶炼工艺制备的大尺寸M50轴承钢坯。

航发轴承套圈电磁辅助轧制成形残余应力和组织演变

8Cr4Mo4V轴承钢被广泛应用于航空发动机主轴轴承,其热轧成形过程中易出现晶粒粗大等缺陷,导致强韧性不足。冷轧成形可实现晶粒细化,提高轴承钢的综合力学性能,具有巨大应用潜力,但8Cr4Mo4V轴承钢的碳含量和合金含量较高,冷轧过程中易产生微纳损伤和应力集中等缺陷。提出了电磁能场辅助轴承钢冷轧成形的创新技术思路,研究电磁辅助轧制对8Cr4Mo4V轴承钢残余应力和组织演变的影响。结果表明,电磁辅助轧制可调控轴承钢位错密度,减少碳化物与相界处的位错缠结,使残余应力均匀化并提高拉伸性能,实现8Cr4Mo4V轴承钢细晶低损伤成形。

船舶柴油机主轴承温度过高问题的处置及预防工作方案

船舶柴油机在使用过程中,主轴承突发故障时有发生,主要表现现象为主轴承温度过高。如未能及时有效处理,将严重影响柴油机的正常运行。本文从故障机理的角度出发,研究主轴承温度过高的各项成因,并分析故障的各种表现形式。基于滑油温度过高、滑油压力过低或无压力、曲轴箱中出现异常敲击声等主要的附加故障特征,本文分析故障发生后的主要危害,重点探讨故障的处置流程和排除方法,进而提出故障预防方案,为船舶柴油机的安全使用与维护提供理论依据。

高温环境Si_(3)N_(4)陶瓷与M50钢材料的球盘配副与润滑油量对摩擦学行为的影响研究

针对耐高温轴承的高温润滑问题,采用SRV-Ⅳ微动摩擦磨损试验机对轴承用材料Si_(3)N_(4)陶瓷和M50钢展开了高温控油摩擦磨损试验,之后对不同的配副方式进行了高温足量油、乏油的摩擦磨损对比试验.控油试验结果表明:200℃、足量油润滑条件下,Si_(3)N_(4)(球)-M50(盘)配副相较于M50钢自配副具有更低的摩擦系数和盘磨损率.M50钢自配副磨损率更容易受到润滑油量的影响.这是由于Si_(3)N_(4)(球)-M50(盘)配副的M50盘表面在摩擦过程中生成了稳定的含磷摩擦反应膜,而M50钢自配副的磨损以磨粒磨损为主,化学反应膜容易被破坏,且磨粒浓度会受到润滑油量的影响.不同配副对比试验结果表明:200℃、3μL油量下,仅M50(球)-Si_(3)N_(4)(盘)配副长摩1 h未发生润滑失效,且能够保持较低的磨损率,除摩擦过程中产生的反应膜能够起到保护作用外,M50钢球表面化学反应膜成膜面积更小,成膜不易受乏油条件的影响也是重要原因.

龙凤山气田易漏井不承压泡沫水泥浆固井技术

中国石化龙凤山地区面临井温高、地层承压能力低、周期长、承压堵漏成本高等系列固井技术难题,导致固井周期长、费用高且固井质量无法保证等。为解决上述问题,在分析工区现有固井工艺的基础上,提出了不承压泡沫水泥浆固井设计思路,形成了龙凤山地区不承压泡沫水泥浆固井工艺,建立了泡沫水泥浆井内密度及恒密度注气固井计算方法与固井工艺;优选了发泡剂、降失水剂和早强剂等泡沫水泥浆关键外加剂,开发了新型低密度泡沫水泥浆体系,耐温性可达到120℃以上,泡沫半衰期大于420 s、水泥浆30 min失水32 mL、48 h强度13.3 MPa,各项性能均可满足中石化龙凤山气田高温、深井固井要求;形成了适合于龙凤山气田泡沫水泥浆固井技术。现场11口井应用表明,该项技术能够有效提高固井质量,避免了固井前承压、分级或尾管固井作业,平均节约承压堵漏周期7 d以上,经济效益显著。龙凤山气田泡沫水泥浆固井技术对解决中国石化其他工区深井、高温井固井漏失、承压堵漏等难题具有重要借鉴意义和可持续性推广价值。

电脉冲辅助冷却的M50钢热环轧组织性能调控

热环轧是目前M50钢制轴承套圈的主流制造工艺,其工艺流程较长,长时间的保温导致晶粒粗大且耗时耗能。将电脉冲工艺与热环轧工艺相结合,提出电脉冲辅助轴承套圈热环轧冷却(EP-HRR)的新方法,研究了不同峰值电流辅助下热环轧试样的组织与力学性能演变。结果表明:脉冲电流可降低M50钢相变发生的活化能,促进奥氏体再结晶,有助于缓解轧制过程中的局部应力集中;随着峰值电流增大,变形晶粒向回复晶粒转变,进而向再结晶晶粒转变,这归因于脉冲电流非热效应下再结晶所需自由能的降低以及再结晶形核速率的提升;高峰值电流辅助M50钢制轴承套圈热环轧冷却有助于降低试样的各向异性及截面硬度,电脉冲辅助冷却一定程度上可起到回火功效。

高速液压缸导向套静压支承温度场分析

高速液压缸是电液伺服控制系统的执行元件,其导向套静压支承结构具备优良的导向性能、抗偏载力、低摩擦力,可以大大影响系统的控制精度以及动静态性能。通过理论分析得到不同工况会引起静压支承油膜的温度变化,而温度变化对导向套静压支承的承载力影响很大。应用Fluent对液压缸活塞杆导向套处静压支承的温度场进行建模仿真,分析活塞杆偏心量、入口流量、活塞杆移动速度与油膜温度的关系以及油膜的温升与油膜承载力的关系。结果表明:随着偏心量的增大,轴向封油面的温升越来越大,同时温升较大的面积占比增多;入口流量与温升成正比关系;活塞杆往复直线运动带动液压油运动,油膜产生温升;同时,油膜温度升高,油膜支承力减小,导向套静压支承性能降低。

汽车高速驱动电机轴承高低温试验机

新能源电动汽车驱动电机轴承的性能及寿命是用户和轴承生产厂家非常重视的问题,驱动电机轴承出厂前需进行一系列相关检测。为满足轴承出厂前的检验要求,研制出一台驱动电机轴承试验机,主要由试验主体、试验台架、加载系统、驱动系统、高低温环境发生系统以及电气测控系统组成。通过6206深沟球轴承的装机试验,试验过程中试验机整体运转平稳,各测量参数显示正常,试验后轴承的各项尺寸精度指标满足产品设计要求。