Static and dynamic characteristics of active-head sliders

Active-head sliders with a unimorph piezoelectric actuator for flying height control were experimentally evaluated. It was found that the stroke of the actuator is 1.3 to 1.5 nm/V without flying over the disk. The adjustment amount of flying height is about 1.4 nm/V when the active-head slider is flying over the disk. It was found that flying height could be reduced and decrease from 24 to 10 nm by applying 10 V to the actuator under flying condition. Both the air pressure generated at the active-pad and the impact pressure due to the head/disk contact must be taken into account for precise control of flying height.     

硬盘磁头激光锡球焊接有限元分析

介绍硬盘磁头激光锡球焊接的原理和优点;统计分析了焊接缺陷主要是表现为锡球断路、焊锡过流、锡球分布不对称以及烧焦和锡溅,主要受锡球大小、焊盘相对位置以及有关加工参数的影响。通过有限元模拟,得出最优的锡球直径和焊盘位置参数。生产实践证明,模拟结果数据效果良好,产品合格率增加。     

双滑块驱动2自由度五杆机构的运动特性分析

工业操作常常需要作各种平面曲线运动,不仅对轨迹形状有要求,而且对其运动特性(速度、加速度)也有要求.文中研究一种简易实用的两驱动滑块在同一导轨上运动的2自由度平面五杆机构,推导了该机构运动学正反解计算公式,基于其运动学反解仿真分析了该机构末端操作点行走轨迹满足各类直线、圆轨迹及封闭组合曲线时,两滑块驱动运动规律及特性,为这种简易2自由度操作手的实时控制及工业应用奠定了基础.     

共轭圆柱凸轮轴向滑片压缩机

共轭圆柱凸轮、圆盘、缸套、轴、轴向滑片形成工作容腔，它们既是轴对称的也是面对称的。随着凸轮的转动，滑片受共轭凸轮的约束在圆盘的槽内滑动，基元完成吸气、排气循环。气体的作用力与滑片的惯性作用力相互平衡，卸去轴承的负荷，压缩机运转平稳、振动小。     

Tribological performance of nano-thin fluoropolymer coated sliders

With the increase in recording density, any accumulation on slider surface can cause serious problems, such as high fly–stiction and extensive slider–disk interaction. Therefore, how to mitigate the accumulation on slider surface and thus, improve the stability and reliability of head–disk interface is becoming an important issue. In this work, a nanothin fluoropolymer overcoat with very good oleophobic and hydrophobic properties was applied on slider surface with a dipping process. Tribological performance, such as fly–stiction, normal stiction, and takeoff and landing processes, of the coated sliders was studied. Test results show that although normal stiction is not lowered, normal stiction modulation is reduced obviously by the overcoat. Fly–stiction and its modulation of coated sliders are much smaller than those of uncoated sliders. Coated sliders show much better takeoff and landing performance during contact start stop tests. After tests, the surfaces of tested sliders and disks were examined with an optical microscope, surface reflectance analyzer, and TOF–SIMS to interpret the tribological performance of the coated sliders. It can be concluded that the fluoropolymer overcoat reduces the amount of accumulation on slider surface and thus, improves the tribological performance of the coated sliders.     

轴向滑块凸轮式差速器的运动仿真

利用三维软件对轴向滑块凸轮式差速器各零件进行了三维参数化建模、虚拟装配、干涉检查和模拟仿真，简化了研发过程，缩短了研发周期。降低了研发成本。通过运动仿真还能及时地发现产品设计中存在的问题，提高产品的综合性能。仿真结果表明，该差速器在直线行驶和转弯行驶两种状态下，基本上都能满足“两侧差速轮的角速度之和等于差速器壳角速度的两倍”这一关系。     

Pumping effect of sliders in hard disk systems

The accumulation of contaminants on the slider surface is of paramount importance in hard disk drives because only an ultra small amount of contaminants on the slider surface will cause catastrophic failures for hard disk drives with a spacing between the slider and the hard disk as small as 10 nm, which will be reduced further in the near future to about 5–6 nm in order to attain a recording density of 100 Gbit/in². In this paper the pumping effect of the slider is proposed as one mechanism of the contaminant accumulation on the slider. Analysis of the pumping effect is conducted by considering the adsorption process and the shear flow process on the slider surface in terms of the continuum. It is found that the pumping effect can be divided into two different classifications depending on the value of the parameter λ which is the ratio of the maximum shear flow of the adsorbed film to the maximum adsorption amount: the shear flow rate-controlling pumping effect for λ < 0.1 and the adsorption rate-controlling pumping effect for λ > 0.4. For the shear flow rate-controlling effect, the accumulation rate of the contaminant is directly proportional to the disk surface velocity, while inversely proportional to the flying height of the slider. An erratum to this article can be found at .     

Effects of striated texturing on pivoted gas sliders

The paper is a study of effects of striated, transversely oriented texturing on pivoted gas lubricated sliders. Unlike the author's recent works on texturing, in the present case the complete slider surface is textured. To simplify the analysis, the high bearing number approximation has been used to calculate load carrying capacity and stiffness for just a few macro-geometries. The averaging operators derived for incompressible fluids are also valid for gases [Tønder K. Theory of effects of striated roughness on gas lubrication. In: Proceedings of the JSLE international tribology conference, Tokyo, Japan; 1985. p. 761–6; Weissner S, Tønder K, Talke FE. Surface roughness effects in compressible lubrication. In: Proceedings of the Austrib’98 international tribology conference, Brisbane, Australia; 1998. p. 111–22.]. These have been used here. It is seen that texture in the form of longitudinal furrows is not beneficial for very thin films, when the high bearing number approximation is acceptable. As in Ref. [Tønder K. A simplified assessment of the performance of differentially textured hard disk sliders. Tribol Int 2005;38(6/7):641–5], the study is limited to transverse grooves.The performance of pivoted textured sliders has been compared with that of more conventional designs. Plain textured geometries are found to have stiffness properties somewhat poorer than those of most current slider designs. However, they do possess realistic stiffnesses; this makes the concept of texturing standard slider surfaces rather appealing. It seems probable that texture may provide some damping.Finally, it is suggested that texturing liquid lubricated bearings may, under certain conditions, prevent bearing failure caused by bubble-induced compressibility of the lubricant.     

麦克弗逊前悬架参数灵敏度分析及优化

这里利用多体动力学理论，建立了麦克弗逊前悬架模型，并运用实验设计技术对麦克弗逊前悬架运动特性进行分析。实验设计技术使得我们很方便地找出对悬架系统性能影响最大的设计因子。运用优化设计技术，获得性能良好的悬架系统。     

Development of contact sliders with nanotextures by femtosecond laser processing

The information on the frictional resistance of a self-propelled robotic capsule endoscope moving inside the body is very important for the design and the performance enhancement of such parameters of the capsule endoscope as power consumption, motion control and positioning accuracy. Based on this motivation, the ultimate goal of this research was to develop an analytical model that can predict the frictional resistance of the capsule endoscope moving inside the living body. In this work, experimental investigations of the fundamental frictional characteristics and the viscoelastic behaviors of the small intestine were performed by using custom-built testers and various capsule dummies. The small intestine of a pig was used for the experiments. Experimental results showed that the average frictional force was 10–50 mN and higher moving speed of the capsule dummy resulted in larger frictional resistance of the capsule. In addition, the friction coefficient did not change significantly with respect to the apparent area of contact between the capsule dummy and the intestine, and also the friction coefficients decreased with an increase in the normal load and varied from 0.08 to 0.2. Such frictional behaviors could be explained by the lubrication characteristics of the intestine surface and typical viscoelastic characteristics of the small intestine material. Also, based on the experimental results, a viscoelasticity model for the stress relaxation of the small intestine could be derived.     

粉尘颗粒阵列传感器灵敏度分析

为了更好的实现粉尘颗粒浓度的测量,对阵列式光学传感器的灵敏度场进行了数学建模和分析,对传感器权重系数进行了计算。分析了不同阵列结构传感器的灵敏度系数。最后根据数学模型使用C语言进行了编程计算,并对四种结构的传感器灵敏度进行了仿真分析与图形仿真。     

蒸发波导诊断模式敏感性分析

研究蒸发波导特征量对边界层气象水文要素的敏感性对于评估目前蒸发波导观测设备的精度指标和利用海气耦合数值预报模式预报蒸发波导特征参数的可行性研究具有重要的参考价值。本文介绍了Paulus-Jeske模式(P-J模式)和Babin模式确定蒸发波导高度的方法,并利用P-J模式和Babin模式诊断分析了不同的输入参数对于模式敏感性的影响。结果表明:在稳定层结条件下,Babin模式对于气温的扰动最敏感,P-J模式对于相对湿度的扰动最敏感;在不稳定层结条件下,Babin模式对于海表温度的扰动最敏感。P-J模式对于相对湿度的扰动最敏感。总之,Babin模式对于气象水文要素扰动的敏感性比P-J模式的大。     

Analysis and optimization of dynamic response of air bearing sliders to disk waviness

Flying stability has been becoming more critical for air bearing sliders with extremely low flying height (FH). Therefore, the effects of disk waviness on flying height modulation (FHM) cannot be neglected. This paper presents an analytical study on the mechanism of FHM of air bearing sliders due to disk waviness, and a design optimization for increasing waviness following ability of sliders. An analytical three-degree-of-freedom (3-DOF) model is developed, where the air bearings are modeled as six lumped linear springs and dampers. The purpose of this model is to develop a quantitative understanding of how air bearing sliders respond to disk waviness. The dynamic characteristics of the slider-air bearing system are then analyzed, and the closed-form frequency resonance function (FRF) of FHM to disk waviness is derived. The impact of disk surface features and the positions of the trailing pad, the side pads, the leading pads and the negative pressure center on FHM are also investigated using parametric analysis. The analysis results show that the improvement of the roll-off characteristics of the disk surface waviness can also decrease the FHM. In addition, shortening the distance between the trailing pad pressure center and the head position, moving backward the side pads and leading pads and forward the negative pressure center can increase waviness following ability of the slider. Finally, an air bearing slider is designed according to the proposed design strategies for reducing the FHM due to disk waviness.     

城市客车车身结构灵敏度分析及优化

建立了某客车车身骨架的有限元分析模型,利用ANSYS软件就该车的车身骨架对车身扭转刚度和一阶扭转频率的灵敏度进行分析,根据灵敏度分析结果选择设计变量,以车身扭转刚度和一阶扭转频率为状态变量,以车身骨架总质量为目标函数进行优化.     

Measurement of wear of carbon coated sliders using atomic force microscopy and Raman spectroscopy

Wear of carbon coated sub-ambient pressure “pico” sliders is investigated during sweep testing as a function of interference height, slider design and sliding distance using atomic force microscopy. The wear results from atomic force microscopy measurements are compared with wear measurements of the carbon overcoat using Raman spectroscopy. The effect of interference on wear and disk burnishing is studied using acoustic emission measurements and atomic force microscopy. The results show that wear of a slider is higher for larger interference height and higher stiffness of the air-bearing.     

计算机硬盘磁头滑块的设计与加工研究

研究计算机硬盘磁头滑块承载面结构的设计理论与加工方法。分析了现有磁头滑块的结构特点及其设计理论和设计方法;利用光刻及干法刻蚀的工艺及设备,进行了所设计磁头滑块的微加工;并利用三维表面形貌测量仪对所加工的磁头进行了加工质量分析,给出实验测量值与设计值的比较结果。     

A simplified assessment of the performance of differentially textured hard disk sliders

The recently introduced concept of differentially tailored tribo-devices has been extended to hard disk sliders. In this first paper dealing with the subject, the high bearing number approximation has been used to calculate load carrying capacity and stiffness for a few micro- and macro-geometry combinations. The author has previously shown that the averaging operators derived for incompressible texture are also valid for the compressible case. From this it follows that texture in the form of longitudinal furrows is not beneficial. This introductory study therefore involves transverse grooves only.The predicted performance has been compared with that of more conventional sliders. It is found that the new concept may lead to sliders having stiffness properties better than those of most current slider designs known to the author. It is also argued that the texture of these new surfaces, which should be easy to manufacture, may provide some damping.     

Behavior of ultrathin liquid lubricant films for contact sliders in hard disk drives

In this paper, we describe the behavior of ultrathin liquid lubricant films for contact sliders in hard disk drives. In the experiments, the ultrathin liquid lubricant film behavior is investigated using Zdol and cyclotriphosphazene-terminated PFPE lubricant which have different end groups as a function of lubricant film thickness. The disks are examined with a scanning microellipsometer before and after contact slider experiments. It is found that the lubricant film thickness profiles almost do not change, when the lubricant film thickness is less than one monolayer. It can also be observed that lubricant film thickness instability due to dewetting occurs as a result of slider-disk contacts for the tested lubricants and the films undergo spontaneous redistributions, resulting in significantly nonuniform film thickness profiles, when the lubricant film thickness is thicker than one monolayer. In addition, it is found that the observed behavior of ultrathin liquid lubricant films for cyclotriphosphazine-terminated PFPE lubricant contrasts markedly with that for Zdol. The difference between cyclotriphosphazene-terminated PFPE lubricant and Zdol is only the functional end group. Therefore, it may be concluded that their unstable lubricant behavior depends on the chemical structure of functional end groups.     

Acoustic emission studies of thin film rigid disks and proximity recording sliders and its applications to tribology

This work investigates the flying and contact phenomena of proximity contact recording sliders and their effects on the tribological performance of thin film media by the use of acoustic emission analysis. Proximity contact recording sliders included negative pressure and tri‐rail types of tripad sliders. Mechanical and laser‐induced textured magnetic rigid disks were used in this study. The laser bump heights of laser textured disks were controlled to achieve a desired tribological performance and the relationship between the laser bump heights and acoustic emission energy during drag and start/stop testing for different slider designs was studied. Emphasis was also placed on identifying the critical parameters of media and slider designs for tribological performance improvement. An analysis of the slider body natural frequencies during flying at the operational speed has been demonstrated to be well correlated to the contact behavior at the head‐disk interface. Moreover, the environmental and lubrication effects on the fixed tracking flyability performance were investigated and the acoustic emission data also agreed fairly well with the observed degree of contamination on sliders and degradation on the textured media. This revised version was published online in July 2006 with corrections to the Cover Date.     

Sensitivity analysis of track parameters on train-track dynamic interaction

Dynamic behavior of railway tracks when trains are running is influenced by several factors, i.e. rolling stock, the components of superstructure and their specifications. Usually, features like the sleeper spacing, rail pad stiffness, ballast damping and stiffness have an effect on the dynamic response of the track. The best method to study the dynamic behavior of the track is to model the track assembly and the train as a whole and carry out an analysis of dynamic interaction. Such analysis makes the identification of the track’s dynamic behavior easer and helps to anticipate the deterioration of the track elements, and determines the effects of increase or decrease of mentioned parameters. This paper presents track-train dynamic interaction without considering irregularity of the rail face. A sensitivity analysis was carried out on the selected model. The analysis was undertaken with the view of varying one of the mentioned parameters and the results were presented to further identify the deterioration of the track elements. The results indicate that reducing sleeper spacing, rail pad stiffness, ballast stiffness, and increasing ballast damping reduces wheel-rail, rail-sleeper, and sleeper - ballast contact forces.