螺旋面扇形瓦推力轴承势动力润滑性能分析

提出了一种适用于推力轴承的新型瓦－螺旋面扇形瓦,并对其热动力润滑性能进行了分析。螺旋面瓦与平面瓦比较,因此本身具有一定的斜度而具有许多特点,如油膜厚度大,承载能力大,剪切速率低,粘性耗散小,温升较小,功耗少而且制造加工容易等,因此可以很好地取代平面扇形瓦。     

螺旋面扇形固定瓦推力轴承润滑性能分析

为研究螺旋面扇形固定瓦推力轴承的润滑性能,建立了柱坐标下螺旋面扇形瓦油膜厚度方程,计入工质离心力,采用数值方法对比研究了螺旋面瓦与斜-平面瓦轴承润滑性能,分析了结构参数及周向、径向油膜厚度比对螺旋面瓦轴承承载能力、功耗,润滑油温升、泄漏量的影响。结果表明:在相同结构参数及运行条件下,螺旋面瓦轴承承载能力大于斜-平面瓦,温升低于斜-平面瓦;对于螺旋面瓦轴承,合理的周向、径向油膜厚度比分别为2.5、1.5。按最优油膜厚度比设计的轴承,可使其承载能力提高的同时降低功耗和温升。     

斜螺旋面—平面组合扇形固定瓦推力轴承的性能

本文对斜螺旋面一平面扇形组合瓦推力轴承性能和润滑油离心效应进行了分析,取得反映离心力影响程度的无量纲数的判断值和瓦面斜面部位的周向与径向间隙比的最佳搭配关系,系统地给出了这类轴承的设计计算用线图和资料。图9表6参4     

圆形可倾瓦与扇形瓦推力轴承性能的比较

应用有限元程序分别对圆形瓦和扇形瓦推力轴承在中心支承条件下的性能进行了计算。并根据计算结果对两种瓦形的轴承性能作了比较。其结果和实验结论比较一致。最后得出圆形瓦轴承比扇形瓦轴承在某些方面有一定的优越性。     

螺旋面瓦推力轴承承载能力分析

建立不同结构参数的螺旋面瓦推力滑动轴承润滑模型,并用FLUENT软件进行仿真计算,研究油膜厚度、瓦面螺距以及转速对轴承承载性能的影响规律,为螺旋面瓦推力轴承的设计提供理论基础。结果表明,油膜最高温度随着螺距以及油膜厚度的增加而减小;轴向承载力随着油膜厚度的增加而降低,当最小油膜厚度和转速固定时,存在最优的瓦面升高比使得轴承承载力最大,瓦面升高比为1.4;油膜最高温度与承载力均与转速呈直线型关系;螺旋面瓦的承载力远高于平面瓦。     

速度对扇形可倾瓦推力轴承润滑性能的影响研究

采用数值分析方法研究速度对扇形可倾瓦推力轴承润滑性能的影响,分析速度对最小油膜厚度、最大油膜压力、最高油膜温度、功率损失和流量等参数的影响规律,得到了速度与扇形可倾瓦推力轴润滑参数的关系。结果表明:最小油膜厚度在一定的速度范围内随速度呈线性变化,且随着速度的增加而增加;最大油膜压力随速度的增大产生波动性变化,但最终逐渐稳定到某一具体值;随着速度的增加温度升高;瓦功耗和瓦流量随速度的增加基本上呈线性增加变化。     

船用水润滑推力轴承扇形推力瓦润滑性能数值分析

采用数值分析方法研究了船用水润滑推力轴承扇形推力瓦的润滑性能问题,计算得出了水膜厚度、压力分布、推力瓦位移场和温度场的三维分布规律.研究表明:在推力瓦不同位置有着较大温度差,水膜最大厚度和最大压力、推力瓦最高温度和最大变形均出现在推力瓦周向出水口的位置.     

基于CFD的水润滑斜－平面瓦推力轴承承载能力分析

水润滑斜-平面推力轴承用水作为润滑介质,传统油润滑斜-平面推力轴承的计算公式及图表不再适用。基于计算流体动力学(CFD)理论,建立不同的水膜润滑模型并进行仿真计算,在水槽尺寸一定时,分析最小水膜厚度、瓦块中径上瓦斜面升高比、瓦块中径上斜面和平面之比以及转速对某斜-平面瓦推力轴承承载力的影响。结果表明:水膜的厚度是影响水膜承载力的主要因素,水润滑斜-平面瓦轴承轴向承载力随着水膜厚度的减小而增加;当水槽尺寸、最小水膜厚度以及转速一定,瓦斜面占长比为0.7、瓦斜面升高比为2时,轴承承载能力最大;在靠近水槽的轴承壁面上产生了空化现象;对于某个特定结构的轴瓦,推力环转速的变化不影响水膜压强中心的位置。     

阶梯面固定瓦推力轴承结构改进及性能分析

针对瓦面上沿内、外径同时设置阻流边的阶梯面扇形固定瓦推力轴承，就其基本参数阻流边宽度对轴承性能的影响进行了计算和分析，并提出了该参数的最佳值。     

基于MATLAB的阿基米德螺旋面法线和切平面的求解研究

提出了一种基于MATLAB的阿基米德螺旋面法线和切平面的求解方法。该方法首先阐述了螺旋面原理,然后对其法线和切平面求解进行了推导,同时解决了在求解过程中关于MATLAB转换坐标时保证θ0的对应值这一重要问题,最后通过运行实例验证该求解方法。实验结果表明该方法具有可行性和正确性。     

大型机床垫板类铸件工艺改进的研究

垫板是大型机床的重要部件的组成部分,多年来因其铸造成品率较低,不能满足生产的需求。通过优化垫板的铸造工艺,改进浇注系统,合理的设置补缩冒口,对容易出现缺陷的部位进行有效的补缩,提高了铸件成品的合格率,降低了生产成本。     

Dependence of pad performance on its texture in polishing mono-crystalline silicon wafers

Mono-crystalline silicon wafers are important materials in the semiconductor industry for fabricating integrated circuits and micro-electro-mechanical systems. To ensure high surface integrity of polished wafers, the effect of pad texture and its variation on the pad performance needs to be understood. This paper studies experimentally the dependence of pad performance on its texture deterioration by investigating its correlation with polishing time, polishing pressure, and material removal rate. The study concludes that material removal rate decreases as the cylindrical cell structure of a pad is gradually deteriorated, that there is a pad life limit beyond which polishing quality can no longer be maintained, and that the workable pad life can be extended to a certain degree by applying higher polishing pressure.     

Predicting the Material Removal in Polishing: The Applicability of Two Types of Statistical Models

This article develops two statistical rough surface models to investigate the material removal rate in surface polishing. Model I implies that the contact between two surfaces is equivalent to that between a composite surface and a plane; but Model II is without the equivalent surface concept. The prediction differences of the two models were first investigated with the aid of contact mechanics. The analysis shows that the relative error of the predictions by the two models could be minimized by considering the interactions between asperities, and that this error increases with the separation of the mean planes, but decreases with the asperity density, asperity radius and standard deviation of the asperity height. By extending the models to study the material removal rate in polishing, it was found that asperity interaction is an important factor in a statistical modelling of polishing, and that with a given separation of the reference planes of the pad and workpiece surfaces, the material removal rate increases with the volume concentration of abrasive particles and varies with the pad roughness. The study also showed that the microstructure of a polishing pad has a significant effect on the material removal rate of a polishing.     

RZS盘式制动器制动倍率的研究

介绍了RZS盘式制动器的常用工作制动、停放制动和手动释放3种工况下的工作原理。分析和计算了该制动器的自由度,并根据两侧闸瓦间隙值的不同初始状态,确定了各运动铰点在制动前后的位置。对各零部件进行了静力学分析,得到了作用在推盘活塞上的压缩空气力和制动力之间的关系式。研究和比较了闸瓦间隙补偿前后的制动倍率变化规律。计算结果表明：闸瓦间隙值的微小变化会导致制动力产生较大波动。     

DRESSING CHARACTERISTICS OF ORIENTED SINGLE DIAMOND ON CMP POLYURETHANE PAD

Diamond conditioners or dressers are commonly used to dress polishing pads that are applied in the chemical mechanical polishing (CMP) of silicon wafers for integrated circuits. In this work the fundamental characteristics of dressing action on the polyurethane pad are investigated for dressing by a single diamond with various shapes (point-cutting, line-cutting and face-cutting), and the polishing rates of silicon dioxide by the resulting pad are studied. Experimental results reveal that a groove with ridges on both side walls is formed as the diamond is moved over the pad. The cutting action dominates when the point-cutting is responsible for dressing. On the contrary, the plowing action plays a major role under face-cutting. A large spring back reduces the protrusion of the diamond in contact with the pad surface as groove depth is smaller than dressing depth. The use of point-cutting is beneficial since it results in the least damage to the pad and a higher but less variable polishing rate.     

弹性金属塑料轴瓦压缩性能的实验研究

弹性金属塑料轴瓦是大型水轮发电机推力轴承的关键性部件，其性能的好坏直接影响到整个系统运行的动态品质。本文通过对金属塑料轴瓦实际模型的压缩性能进行实验研究，发现其压缩弹性模量与巴氏合金轴瓦等金属材料者不同，不是一个固定的常数，而是随着压力的增大，其弹性模量也逐渐地增大。     

Factors influencing the dressing rate of chemical mechanical polishing pad conditioning

The primary consumables in the chemical mechanical polishing (CMP) process are the polishing pad and the slurry. Among those consumables, the polishing pad significantly influences the stability of the process and the cost of consumables (CoC). Furthermore, the small holes on the pad surface will be filled by the reactant from the CMP process, and the surface of the pad will deposit hard glazing gradually. The glazing not only reduces the ability of absorbing slurry of the pad, but it also causes scratching on the work piece. In order to maintain the stability of the CMP process and return to an ideal pad surface status, we must condition the pad according to a regular time schedule. At the same time, if we use different pad conditioning factors, the dressing rate of the CMP pad will be different. Most important of all, we have to decrease the pad material abrasion due to the pad conditioning process. In conclusion, if we can understand the influence of the dressing rate and conditioning factors effectively, it will be useful for maintaining CMP process stability, extending pad life, and reducing CoC and non-processing time.     

纳米聚集氧化硅固定磨料抛光布的抛光特性

针对传统磨料的固定磨料抛光布容易在加工表面产生划伤,以及材料去除效率低等问题,提出了采用微米级球形聚集氧化硅粒子的固定磨料抛光布。将纳米聚集氧化硅粒子添加到抛光布中,用pH为10.5的碱性水溶液替代传统的抛光液,进行了Si基板的的抛光加工试验。与传统采用不规则形状天然氧化硅及球形熔融氧化硅固定磨料抛光布进行了比较,得到了纳米聚集氧化硅的固定磨料抛光布的加工特性,并讨论了它的基本参数对加工特性的影响。实验得到了与现行纳米抛光液(重量百分比为3%,pH=10.5)相同的材料去除率,加工表面粗糙度降低了约30%。与传统不规则形状天然氧化硅磨料抛光布相比,纳米聚集氧化硅抛光布的磨料为球形,弹性系数仅为其1.4%~60%,因此不易划伤抛光表面。与熔融氧化硅抛光布相比,纳米聚集氧化硅抛光布在pH为10.5的碱性水溶液中磨料表面可吸附的[-OH]离子提高了25倍,使得液相化学去除作用增大至去除率的70%以上。另外,随着纳米聚集氧化硅的微米粒径的增大,固定磨料抛光布的纳米级加工表面粗糙度几乎不变,但对前加工面表面粗糙度的去除能力明显增大,表现出微米粒径效应。     

Analysis of heavy duty tilting-pad journal bearing taking into account pad distortion and possible adoption of rubber pad segments

In this work a comparative study has been made between the thermo-hydrodynamic performance of a three shoe tilting-pad journal bearing with rigid and elastic pads subjected to unbalance load. A case study of a bearing adopting three rubber pad segments has also been studied. The distortion of the elastic pad is introduced into the distribution of the film thickness through an iterative scheme to assess its effect on the load carrying capacity of the bearing. A finite element mesh is used to calculate the distortion of the elastic pad while a finite difference mesh is used to calculate the pressure field in the lubricant film. Results have shown a number of interesting conclusions regarding the adoption of rubber pad segments instead of tilting-pads. There is an increase in minimum oil film thickness when using elastic pad or even rubber pad segments compared with rigid pads. Also the maximum pressure and load carrying capacity are not significantly affected.     

3#TRT发电机组推力瓦温度超标原因分析及处理

3#TRT发电机组至07年投产以来,由于高炉炉况不稳定,一直低负荷运行,推力瓦温度也在正常范围内。近年来,随着炉况逐步恢复,负荷逐渐增大,推力瓦温度已超出规定值。文中通过对该缺陷原因分析及处理,收到明显效果,为今后处理类似缺陷积累了经验。