【作者】 唐正强；

【导师】 夏伟；

【作者基本信息】 华南理工大学 ， 机械制造及其自动化， 2014， 博士

【摘要】 信息技术的不断发展对信息存储容量及存储安全性能的要求越来越高。超高密度存储硬盘的出现，使得磁头越来越贴近磁盘盘面，目前使用的硬盘中磁头与磁盘之间的飞行高度仅为几个纳米左右。硬盘正常工作时磁头的加载、卸载、动态飞行及寻址等动作会引起窝点与挠臂发生微小相对位移，导致窝点与挠臂的微动磨损，破坏窝点与挠臂间的接触面，影响磁头浮块的动态飞行能力。窝点与挠臂之间的微动磨损还会产生磨削颗粒，这些颗粒散落在硬盘里，容易卷入磁头与磁盘之间的微小间隙引起接触碰撞，损坏磁头组件与盘面，造成永久的数据丢失。硬盘在受到外界激振力作用时，更容易引起磁头磁盘的剧烈碰撞，从而加剧窝点与挠臂之间的微动磨损。特别是当硬盘处于充氦环境中时，稀薄的氦气在磁头受到挠动时能提供的阻尼作用有限，相同的激振力作用下，磁头磁盘的接触碰撞力远远大于处于空气环境中的硬盘。目前针对磁头磁盘接触碰撞过程中引起的窝点与挠臂之间的微动磨损研究很少。结合悬架有限元模型、浮块与盘面间的动态气浮轴承模型以及磁头磁盘接触碰撞模型，研究了当磁头与磁盘发生接触碰撞时引起的窝点与挠臂之间的动态接触力变化，研究了材料属性对窝点与挠臂动态接触力的影响，模拟了硬盘工作状态下受外界干扰时磁头的动态响应，模拟了较为真实工作状态下窝点与挠臂的动态接触力，为窝点与挠臂间微动磨损数值模拟奠定了基础。在目前较为新兴的充氦硬盘技术中，提出了使用氦-空混合气体来代替纯氦的方法。研究了氦-空混合气体的物理性质，结合动态气浮轴承模型以及粗糙磁头磁盘接触碰撞模型研究了在不同氦气比例下，磁头的动态飞行性能和磁头与磁盘接触碰撞性能。该模拟计算中使用了较新的气浮面设计，通过有限单元法求解了复杂气浮面上各节点的飞行高度和气浮压强。研究了磁盘速度对50%充氦环境中磁头与磁盘接触碰撞的影响。研究发现，氦-空混合气体代替纯氦在冲击载荷下能提供较好的阻尼作用，减少磁头与磁盘间剧烈的接触碰撞。建立了适用于微纳米量级幅值运动的微动磨损实验平台，通过实验方法研究了窝点与挠臂在不同载荷下的微动磨损行为，比较了激光抛光工艺对窝点微动磨损性能的影响。通过力传感器和激光测振仪采集数据与处理，获得了摩擦力-位移微动图和摩擦系数随着微动循环次数增加而演变的结果；通过扫描电镜的测量，计算并比较了抛光与非抛光窝点磨损体积。研究表明，载荷会引起微动磨损区域转变而导致不同的表面损伤机理；表面粗糙度在较小载荷时对磨损体积的影响可忽略不计，但在较大载荷和较长时间的微动磨损中，激光抛光窝点可以显著减小磨损体积；计算了窝点动态微动磨损系数，为后续的微动磨损模拟奠定了研究基础。建立了窝点与挠臂的二维微动磨损模型，应用了实验中获得的摩擦系数及动态磨损系数。采用了改进的Archard磨损方程递进地计算了窝点与挠臂的局部磨损深度，研究并确定了最优的微动循环增量步，极大的减少了模型计算时间。运用该模型预测了不同载荷和微动循环次数下窝点与挠臂的磨痕形貌、接触压强及应力分布等。通过跟实验结果比较，表明该二维模型预测趋势跟实验结果一致但是误差较大，因模型计算较快可以用来定性研究几何尺寸和材料属性对窝点与挠臂微动磨损性能的影响。在二维微动模型基础上，建立了窝点与挠臂的三维微动磨损模型。推导了适应于不同微动位移的局部磨损公式，提出了自适应动态微动循环增量步方法，使以往耗时较长的三维微动磨损模拟在普通计算机上得以实现。通过跟实验结果对比，表明三维模型能更准确地预测窝点与挠臂的微动磨损表面形貌，误差为8.5%。因此，窝点与挠臂的三维微动磨损模型可为悬架窝点与挠臂的研究设计工作提供重要的理论指导。更多还原

【Abstract】 The requirements of information storage density and safety increase with the increasingdevelopment of information technology. The gap between a slider and a disk is becomingsmaller and smaller in an ultra-high density disk. The current flying height is on the order of afew nanometers. The load, un-load, flying and searching performance of the slider will causethe un-stability of the head gimbal assembly, inducing a reciprocate micro-displacement at thedimple/gimbal interface. The reciprocate displacement is treated as fretting wear, whichaffects not only the dimple/gimbal interface but also the flying ability of the slider. In addition,contamination particles are more like to generate and cause serious contact at the head/diskinterface, which will damage the mechanical components disk surface, causing un-restoreddata lost. The head/disk contact is more likely to happen since the head/disk gap is only a fewnanometers if there is an impulsive force. The contact will accelerate the damage of thedimple/gimbal interface. If a hard disk drive is filled with helium instead of air, the dampingeffect is reduced due to helium density is far smaller than air. In this case, larger contact forceat the head/disk interface will be happen compare to air filled disks.Through the literature searching, little information is available about the contact of thedimple/gimbal interface induced by slider/disk contact, especially in helium environment.Therefore, a finite element suspension model, an air bearing model and a slider/disk contactmodel are combined to investigate the contact and friction forces at the dimple/gimbalinterface, especially when the slider and disk contact happens. The effect of dimple materialon the dynamic response of the dimple/gimbal contact is studied as well. The results showthat the contact and friction forces reach their maximum when the slider/disk contact happens.These maximum forces can be used for the fretting wear experiment and simulation as inputparameters.One of the newest technologies of hard disk drives is the helium-filled drives. Instead ofusing pure helium, the using of helium-air gas mixtures is proposed. The physical propertiesof the helium-air gas mixtures are first studied. The slider/disk contact model with surfaceroughness is implemented into the air bearing simulator. The slider dynamic flyingcharacteristic and the slider/disk contact performance in different helium-air gas mixtures areinvestigated. In this simulation, a new design air bearing surface was meshed and the finiteelement method is used to calculate the air bearing pressure and the flying height of each node.The effect of disk velocity on the slider/disk contact in a50%helium50%air gas mixture issimulated. The results show that the helium-air gas mixtures can provide enough damping when there is an external force applying on the slider. Thus, smaller contact force at theslider/disk interface is obtained.An experimental set-up for micro and nano-scale displacement was built. The frettingwear of the dimple and gimbal under different normal loads were carried out and the effect oflaser polishing on the fretting wear results is studied. Using the measurements from a load celland two Laser Doppler Velocimetries, friction-displacement loops and friction coefficient as afunction of the number of fretting wear cycles are obtained. The dimensions of wear scars ondimples were measured by scanning electron microscopy and the wear volume is calculated.The results show that normal load determines fretting wear regime, leading to differentsurface failures. The effect of laser polishing on the dimple/gimbal fretting wear can beneglected if the normal is small. However, if the normal load is bigger and the fretting weartime is longer, laser polished dimple can reduce the wear volume.The two-dimensional fretting wear model of the dimple and the gimbal was built. Thefriction coefficient and wear coefficient obtained from the experimental results areimplemented in this model. Local wear depth of each node is calculated using the modifiedArchard’s wear equation. An optimal fretting wear incremental cycle is determined and thesimulation time is greatly reduced. The model can be used to predict the wear profiles, thecontact pressure and the stress distribution of the dimple and the gimbal under differentnormal loads. The results show that the trends of the simulation are similar to theexperimental results. However, the relative error is big. In this case, the model can be used toqualitatively investigate the effect of geometric and material parameters on the dimple/gimbalfretting wear behavior due to the less calculation time.Based on the two-dimensional model, a three-dimensional model for the dimple and thegimbal fretting wear is built. A new local wear equation is deduced; a coordinates updatingmethod for the finite element model is suggested and an adapted fretting wear incrementalcycles is first proposed. Using these methods, it is possible to calculate the three-dimensionalfretting wear model on a normal computer. The model can accurately predict the wear profilesof the dimple and the gimbal. Comparing with the experimental results, the relative error isonly8.5%. Therefore, the simulation results can be a useful guidance for the dimple andgimbal design.更多还原