Development of an automatic polishing system for aluminum wheel-hub surface

To improve polishing quality and cope with the shortage of skilled workers for aluminum wheel-hub surface polishing, an automatic surface polishing system with hierarchical control based on the teaching-playback method was presented. Multi-axis cutter location data （CL data） were generated with the teaching method. First, a helical tool path and a flexible polishing tool were adopted to achieve high quality and high efficiency; next, the initial irregular data were processed into continuous polishing CL data. The important factor affecting polishing quality, namely the interpolation cycle in the multi-axis CL data was calculated based on a constant removal rate. Results from polishing experiments show that the quality of automatic machine polishing is better and stabler than manual polishing.     

橡胶轮研磨中心高效抛光自由曲面的技术

Polishing is an important finishing process in die and mold manufacturing.Hand polishing takes long time and much labor.Efforts are made to automate the polishing process while keeping accuracy.Recently grinding centers have been developed,which are used for free surface polishing in the present work.The new polishing technique applies the same cutting locus as used in the cutting process to remove only cusp height effectively,keeping the form accuracy generated in the cutting process.     

单晶蓝宝石衬底磨粒抛光技术研究现状

结合单晶蓝宝石衬底磨粒抛光工艺的最新研究进展,从磨粒加工的去除过程出发,综述了应用于单晶蓝宝石衬底抛光的游离、固结、半固结磨料抛光工艺的材料去除模型、工艺特点及各因素影响规律,从材料去除率和表面质量的角度对不同的磨粒抛光工艺展开了分析。根据单晶蓝宝石衬底的应用需求和目前抛光方法存在的不足,指出了蓝宝石衬底超精密抛光技术的下一步研究方向。     

Modeling of polishing process for electric stainless-steel kettle

The market of stainless electric steel kettles is growing significantly, but the main mechanism for polishing kettles via traditional handwork operations limits the growth of electric kettle manufacturing. Based on the successful multi-tool automatic polishing system for electric stainless steel kettles, regression analysis and orthogonal tests were employed to construct a polishing process model, with a purpose to improve the automatic polishing technology for electric stainless steel kettles. The model reveals the relationship between the surface roughness and processing parameters including gringding depth, abrasive tangent speed, workpiece rotating speed and axial feeding speed. Simulation and experimental results are in agreement,which shows that this modeling method is feasible in practice, and it can also be used as a guidance for planning automatic polishing process of electric stainless-steel kettles.     

Singapore international education hub and its dilemmas: the challenges and makings for cosmopolitan learning

ABSTRACT

Higher education in Asia is massifying at an exceptional pace and scale. In this paper, I ask how practices and discourses which inform the internationalization of Singapore’s higher education can provide opportunities for developing cosmopolitan learning that it claims to provide. Cosmopolitan learning is closely related to cross-border student mobility and plays an important role in shaping the international students’ identities, aspirations and worldviews. Based on a recent study in Singapore of a group of international students from various parts of Asia and Europe, this paper attempts to bring the theoretical and grounded realities of cosmopolitan learning in an Asian context into the fore. The aim of the paper is to provide a useful frame for rethinking the purpose of international education for cosmopolitan learning in an increasingly interconnected world that is strewn with ambivalence, and what that means in the context of Singapore as an erudite nation-state critical to building Asian education hub aspirations.     

Evolution of Surface Oxide Film of Typical Aluminum Alloy During Medium-Temperature Brazing Process简

The evolution of the surface oxide film along the depth direction of typical aluminum alloy under medium-temperature brazing was investigated by means of X-ray photoelectron spectroscopy （XPS）. For the alloy with Mg content below 2.0wt%, whether under cold rolling condition or during medium-temperature brazing process, the en-richment of Mg element on the surface was not detected and the oxide film was pure Al2O3. However, the oxide film grew obviously during medium-temperature brazing process, and the thickness was about 80 nm. For the alloy with Mg content above 2.0wt%, under cold rolling condition, the original surface oxide film was pure Al2O3. However, the Mg element was significantly enriched on the outermost surface during medium-temperature brazing process, and MgO-based oxide film mixed with small amount of MgAl2O4 was formed with a thickness of about 130 nm. The alloy-ing elements of Mn and Si were not enriched on the surface neither under cold rolling condition nor during medium-temperature brazing process for all the selected aluminum alloy, and the surface oxide film was similar to that of pure aluminum, which was almost entire Al2O3.     

四轮驱动混合动力电动汽车牵引力控制仿真

设计了四轮驱动混合动力电动汽车的构型,并根据其驱动特性制定了牵引力控制方式和协调控制策略,最后运用Matlab/Simulink对附着系数左右分离的特殊路面进行起步与全负荷加速仿真。仿真结果表明,四轮驱动混合动力电动汽车在牵引力控制系统作用下,其驱动性能得到明显的改善,且各控制器亦能根据不同路面和行车工况进行适当调节,保证了四轮驱动混合动力电动汽车的起步加速性、通过性和车身稳定性。     

用作珠光颜料基材的片状氧化铝的制备

以十八水合硫酸铝作为铝源,采用熔盐法制备了片状六方形氧化铝晶体．通过激光粒度仪、XRD和光学显微镜等检测手段,系统考察了复合熔盐的用量,磷化剂的用量,钛盐的用量,煅烧过程的升温速率以及添加晶种等对晶体的生长过程的影响．研究结果表明：在熔盐与铝盐的比例为4,磷化剂的用量为1．0％,钛盐的用量为1．O％的情况下,可以制备出具有粒径为12μm的六角片状氧化铝．     

Structure optimization of the dispensing house in a combustion train for a thermal bake-out aluminum reduction cell

1. Introduction The bake-out and start-up technologies of aluminum reduction cells is one of the important factors affecting the service life of cells. The service life of cells is of importance to economic benefit in aluminum reduction cells production. Especially for big prebaked cells, the study on bake-out and start-up is even more important. The present methods of bake-out include aluminum fluid bake-out, coke granule bake-out and graphite bake-out [1,2]. The disadvantage of aluminum ba…     

A perspective of microplasma oxidation （MPO） and vapor deposition coatings in surface engineering of aluminum alloys

IntroductionInrecentyears,improvingthewearlifeofAl-basedalloyscomponentsinheavysurfacecontactconditionsbytheapplicationofmicroplasmaoxidation(MPO)coatingshasprovensuccessfulundertechnicalandeconomicconsideration.MPOtechnologyhasrecentlybeentakenasarapid,novelandeffectivemeanstoprovidethickceramiccoatingswithexcellenthardnessandload-bearingcapacityforlightalloymaterials,particularlyaluminumalloys[1].TheMPO,alsocalledplasmaelectrolyticoxidation(PEO),isanadvancedtechnologyforroutineanodizing…     

一种化简二次曲面方程的新方法

利用平面上的坐标轴旋转变换消去两坐标变量的混乘项,再用空间中的移轴变换化简二次曲面方程,得到了化简二次曲面方程的一种新方法,依此方法易见曲面在给定坐标系中的位置。     

铝合金车轮动态径向疲劳试验仿真分析与寿命预测

动态径向疲劳试验是评测铝合金车轮安全性的三大性能试验之一,采用有限元方法实现试验的仿真分析和疲劳寿命预测,能够减少物理试验次数,提高车轮设计研发效率.基于ANSYS Workbench平台,考虑轮胎充气压力对仿真结果的影响,建立了试验仿真有限元模型,实现了15×6JJ铝合金车轮动态径向疲劳试验的仿真分析,运用S-N疲劳分析方法得到了径向试验载荷下车轮的疲劳寿命及损伤分布情况.研究结果表明,轮缘、胎圈座和辐条根部后侧是疲劳损伤的主要集中部位,需要进行设计改进.     

Electrical conductivity and corrosion resistance of ZnFe2O4-based materials used as intert anode for aluminum electrolysis

ZnFe₂O₄ and ZnFe₂O₄-based materials were tested to obtain the electrical conductivity and corrosion resistance in melting bath for aluminum electrolysis. The results proved that adequate additives, such as Ni₂O₃ CuO, Cu, ZnO and CeO₂ would increase the electrical conductivity, and the ZnFe₂O₄-based anodes with these additives were of good corrosion resistance. The current density on anode, the mole ratio of NaF/AlF₃ (MR) and the content of alumina in the bath effect the anode corrosion rate in different way. Project supported by the Science Foundation of Liaoning Province, P. R. China (95 – 156)     

Modified surface tension model for free surface flow with single-phase lattice Boltzmann method

A single-phase lattice Boltzmann model with modified surface tension is developed in this paper to solve the problem of high-density-ratio free surface flow.The computational efficiency and accuracy are both enhanced.The restriction to the relaxation factor （which needs to be smaller than 1） is circumvented by the new surface tension algebra,due to its rational physical nature compared with the treatment of Xing,Buther and Yang in their paper （Comp.Mater.Sci.,2007,39（2）：282-290）.The proposed stable surface tension scheme is applied to simulate the free deformation of a square droplet with surface tension effect and the process of a droplet impinging on a liquid film.The numerical solution for free deformation of a droplet agrees well with thermodynamic principles,and also achieves high accuracy in comparison with Xing,et al.＇s model.Three typical impinging modes are successfully obtained with the new scheme,and another particular mode found by Wang and Chen is also successfully simulated.The evolutions of liquid crown agree well with the power law related to time.     

Control method for exoskeleton ankle with surface electromyography signals

This paper is concerned with a control method for an exoskeleton ankle with electromyography (EMG) signals. The EMG signals of human ankle and the exoskeleton ankle are introduced. Then a control method is proposed to control the exoskeleton ankle using the EMG signals. The feed-forward neural network model applied here is composed of four layers and uses the back-propagation training algorithm. The output signals from neural network are processed by the wavelet transform. Finally the control orders generated from the output signals are passed to the motor controller and drive the exoskeleton to move. Through experiments, the equality of neural network prediction of ankle movement is evaluated by giving the correlation coefficient. It is shown from the experimental results that the proposed method can accurately control the movement of ankle joint. Project supported by the National High-Tech R&D Program (Grant No.2006AA04Z224), the Innovation Program of Shanghai Municipal Education Commission (Grant No.08ZZ48), and the Shanghai Leading Academic Discipline Project (Grant No.Y0102)     

熔体处理易拉罐用铝材的中间退火组织与性能

探讨了经高效熔体处理的易拉罐用铝材中间退火后的再结晶组织、力学性能及制耳倾向的变化规律。结果表明 :经 430℃保温 1h后空冷 ,铝板材的再结晶晶粒组织细小均匀 ,平面塑性各向异性△γ>0且达到最低值 ,断口中的韧窝无明显的大块夹杂与缩气孔存在 ,断裂方式以穿晶微孔聚集型为主 ,综合力学性能较好。     

高效熔剂净化对提高A356铝合金冶金质量和性能的作用

用自行设计的高效排杂净化熔剂对A356铝合金进行净化处理，并用OM、SEM及拉伸性能试验等探讨了该熔剂的净化效果及对提高该材料力学性能的作用。结果表明：RJ-5熔剂的密度和熔点都较其他几种熔剂低，其在特定的过滤处理工艺条件下的排杂净化效果显著，除杂率和气孔降低率分别达52．26％和86．05％；还同时兼有细化和变质的作用，从而使材料的力学性能、尤其是塑性得到了较大幅度的提高(δ的提高幅度达187％)     

高效熔体处理对易拉罐用铝材铸态组织和性能的影响

用高效熔体处理技术制备试验用易拉罐用铝材，探讨了该技术对其铸态组织与力学性能的影响规律。结果表明：高效熔体处理可有效改善和提高易拉罐用铝材的冶金质量，与未处理相比，除杂率与针孔降低幅度分别为71．05％和94．49％，平均晶粒尺寸仅为76．5μm；晶界处第二相为(Al，Fe，Mn，Mg，Si，RE)或(A1，Fe，Mn，RE)复合相，呈短小骨骼状或小球状，晶内(A1，Mg)相呈细小颗粒状；拉伸断口为穿晶微孔聚集型断裂，与未处理相比，抗拉强度与伸长率分别提高16．6％及90．2％。     

Approximate Tangent Plane Method for Calculating Surface Deformation in Elastic Contact Problems

lintroductionThenumericalsolutionofsurfacedeformationinthi-eedimensionalelasticcontactproblemsisthebasisofanalysisofnon-HertziancontactproblemsandtwodimensionalEHLproblems.Mostnumericalmethodsofsurfacedefol.lnationcalculationsubjectedtoanolinalpressuredis…     

Inverse method for the determination of elastic properties of coating layers by the surface ultrasonic waves

INTRODUCTION The elastic properties of coating layers in coating materials are very important in the design and evaluation for engineering purpose. They can serve as ground knowledge in the selection of surface coatings for particular applications, and can be used to monitor the quality of physical processes (Every, 2002). Therefore, estimation of the elastic properties of coating layers is of great practical value. Much effort has been put into measuring the material properties of coatin…