应用液体静压轴承的QP-3立式内圆切片机研制成功

在半导体材料切割机上运用液体、气体静压技术是国外近年来的趋势。它使材料切割机具有精度高,运动平稳,噪声小等特点,能显著提高半导体器件前工序的质量并为后工序创造良好的条件。1445所研制了能够切割φ100直径的半导体材料的QP-3型立式内圆切片机。该机为了自动取片需要大直径中空的主轴,为了满足整机的要求及提高设备精度,QP-3型立式内圆切片机采用了大直径(径向支承直径φ240mm,止推支承平均直径φ270mm)、高转速(主轴转速为2100转/分,径向支承线速度为26.4米/秒,止推支承平均线速度为30米/秒)的液体静压支承的主轴。该主轴静压系统采用了单独供油的止推支承和径向支承,两     

液体静压轴承-主轴系统静态性能的研究

本文以小孔节流四油垫液体静压轴承——主轴系统为例,研究了供油压力、主轴转速、主轴轴线倾斜、轴承温升以及加载角等对静压轴承——主轴系统性能的影响;研究了静压径向轴承的静态性能的计算方法,并通过对一台MBM52W型外圆磨床静压轴承——主轴系统的分析计算,获得了一些有价值的结果。     

超精密空气静压主轴的模态试验分析

以超精密空气静压主轴为研究对象,运用模态试验方法分析其动力学特性,获得结构的模态参数及径向、止推轴承气压变化对转子各阶频率的影响,为修正主轴的动力学仿真模型提供了参考,为评价和优化主轴性能、提高静压支承技术水平提供了支持。     

高速精密轧辊磨头液体止推轴承油膜性能的数值分析

高速精密轧辊磨头止推轴承的性能是影响轧辊磨床加工稳定性和精度的重要因素。Roynolds方程是滑动轴承油膜压力计算的基础,文中基于有限差分法,对Roynolds方程进行量纲一化处理,并借助MATLAB软件强大的符号运算、数值计算及图形可视化处理功能,进行编程计算,求解了高速精密轧辊磨头止推轴承油膜的完整二维流动Roynolds方程。求解结果表明:液体静压止推轴承具有很高的承载能力和较高的油膜刚性,保证了磨头主轴的旋转精度和运动精度。研究结果对于高速轧辊磨床的整体设计具有一定的参考价值。     

立式双立柱数控工作台的安装工艺设计

数控双立柱车床主轴安装高精度双列短圆柱滚子轴承以保证工作台径向跳动,主轴上部装有大承载推力轴承,用于卸去工作台一部分重力,保证工作台端面跳动。主轴调整的好坏直接关系到机床加工精度。工作台一般采用静压导轨结构,为了保证工作台静压导轨的精度和油膜刚度,要求工作台静压导轨油膜间隙控制在0.03~0.04 mm内,使工作台和工作台底座有良好的接触,才能保证工作台静压导轨的正常使用。主轴精度及工作台和工作台底座配合精度的调整,对机床工作精度起着决定性的作用。立式双立柱车床精度的调整,重点在机床主轴精度调整方面。阐述主轴轴承间隙调整和卸荷垫调整方法。按此方法调整装配能有效保证工作台的工作精度。     

内圆磨床使用液体动静压轴承主轴外挂液压站的小型化设计

M2110普通内圆磨床采用液体动静压滑动轴承主轴代替原配置的滚动轴承主轴，主轴径向跳动及轴向窜动精度可提高3个挡次。但液体动静压滑动轴承主轴需要外带液压站，有占地面积大、外带循环油管等不足。通过测量循环时油温设计及确定降温元件、确定油箱最小体积及选取各液压元件、确定液压站附挂内圆磨床位置，实现了外带液压站设计的小型化，可达到主轴改进后内圆磨床一体化的设计效果。     

腔内孔式回油液体静压轴承

一、前言实践证明,液体静压轴承能适应高精度、高效率和重型的机床主轴系统的性能要求,因此,液体静压轴承在这三种类型机床上得到了广泛的应用。而过去广泛采用的定压式静压轴承中,可变节流形式的静压轴承,其油膜刚度较高,但结构比较复杂,在中小型机床上应用受到一定的限制。能否设法在固定节流形式的基础上,经济合理地提高油膜刚度,这就是我们设计和试验新的型式静压轴承的指导思想。同时,我们在新结构的设计中,还考虑了主轴挠度在轴承油膜范围内对油膜刚度的影响,而将主轴挠度的不利因素转化为对提高油膜刚度的有利因素。新的结构型式——腔内孔式回油液体静压轴     

基于流固耦合的插齿机静压主轴结构优化设计

液体静压轴承由于具有较高的旋转精度和油膜刚度等特点广泛应用于精密、高速插齿机主轴上,然而主轴往复运动引起的发热以及摇杆对主轴侧向作用力的周期性变化将导致静压油膜刚度发生变化,从而影响加工精度。针对大齿宽长行程插齿机YKW51160的静压主轴刚度不足问题,建立油膜有限元分析模型,采用静压油腔边缘倒角和回字形油腔2种结构优化设计方案以提高静压油膜刚度和承载能力;基于流固耦合方法对优化后的静压轴承承载能力以及油膜刚度进行分析验证。仿真和实例计算结果表明:优化后的轴承承载能力和油膜刚度最大提升12%和12.3%,满足摇杆对主轴径向周期性的冲击所需的承载能力和油膜刚度要求。     

SFEZ120铣削头主轴装配要点及其分折

本文在分析SFEZ120铣削头主轴结构的基础上,着重阐述了主轴前后轴承获得合理预紧的方法,并深入探讨了通过合理布置前后轴承在主轴圆周方向上的方位,使主轴定心直径相对其两轴承位置的径向跳动和两轴承(成套轴承)内圈的径向跳动三者作用尽可能抵消,以达到提高整个主轴系统装配精度的方法和预期效果。其次也介绍了装配过程中应注意的其他要领和方法。     

基于ANSYS-FLUENT的高精密液体静压径向轴承动静态特性研究

以液体静压轴承为支撑的电主轴是高精密数控机床的一个最为关键的组成部件。静压轴承润滑油膜的压力分布、刚度和温度场的分布直接影响数控机床的加工精度。基于液体静压技术理论,对轴承的流量、静压腔压力和刚度进行数值计算。基于ANSYS-FLUENT联合仿真平台,以液体静压径向轴承的润滑油膜为研究对象,对其压力场、流场和温度场分布等进行了静态和瞬态的研究,仿真结果与数值计算结果取得了很好的一致性。分析表明,静压腔内的润滑油的压力和温度分布不会因为主轴的转速变化而发生明显的变化,而周向封油边和轴向封油边是压力和温度变化的敏感位置。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.