环形气垫震击机构最佳工况的参数选择

本文通过对环形气垫震击机构的功能转换及工况分析,提出了最佳震击工况模式,论述了各技术参数对震击工况的影响,并结合实测资料,对震击机构理论示功图作了全面分析,建立以放大系数α和超越系数θ为特性值的环形气垫震击机构设计计算法。     

中大型闭式压力机气垫缓冲结构的设计与计算

中大型闭式压力机气垫由于气垫力较大,如无缓冲功能,将使机床产生很大的振动,导致机床故障率上升,模具寿命下降,产品合格率也会随之受到影响。为此,以理论计算为基础,实际试验数据为依据,合理设计缓冲机构,效果良好。     

气垫造型机

遵照毛主席关于“自力更生,艰苦奋斗,破除迷信,解放思想”的伟大教导,我们分析、比较了气动震压式造型机、弹簧缓冲气动微震造型机及美国、日本的气垫柱塞式造型机等的优缺点,结合本厂情况,于1973年相继设计了气垫撞击震压式和气垫敲击压震式造型机试验机各一台,于1974年6月投入生产。设计时要求如下: 1.力求结构     

气垫式连续退火炉设计计算

介绍了气垫炉的基本工作原理和设备组成,对气垫炉炉体结构进行设计计算。     

数控液压气垫探析

探析了使单动机械压力机具有深拉深功能且压边力可调的数控液压气垫之控制原理、典型结构、工作功能及性能特点。     

气体辅助挤出中影响气垫形成及稳定性因素分析

对一种新型挤出技术———气辅挤出中的气垫层形成及其稳定性影响因素进行了实验研究和分析,对气体压力的研究表明,当气体压力高于熔体压力时,气流就会影响到挤出口模内熔体的流动,使挤出物表面出现竹节状突起,但气体压力太低时(实验条件下低于0.2MPa)形成不了稳定的气垫膜层;气体流量的大小影响到气垫层的厚度和气垫层内气体的速度,并可通过调整气体流量控制挤出物的截面尺寸;气体温度影响到气垫层的稳定,为保持稳定的气垫层,气体温度应保持和口模温度一致。     

铝带材热处理气垫炉内流动漂浮过程 数值模拟及结构优化

基于洛阳某铝厂设计的气垫炉结构,建立了气垫炉整体的三维物理数学模型,运用流固耦合FSI分析方法,得到了铝带材热处理气垫炉内的流场分布和铝带材表面的压力分布,以及带材在气垫炉内漂浮换热过程中的变形量。以减小漂浮过程中铝带材的变形量为目的,对气垫炉内导流板和狭缝喷嘴宽度进行改造,结果表明,改造后铝带材最大形变量为13.2 mm,较改造前减少了22.2 mm。     

手动调节行程的压力机气垫

压力机的气垫主要用来压边与顶件.根据气垫的行程能否调节,可将气垫分成可调和不可调的.通过设计采用标准气缸替代专用气垫,减少了加工零件,缩短了生产周期,并将气垫行程由原电动调节改为手动调节,大大降低了生产成本,从而提高了经济效益.     

数控液压气垫探析

探析了使单动机械压力机具有深拉深功能且压边力可调的数控液压气垫之控制原理，曲型结构，工作功能及性能特点。     

气垫炉漂浮技术研究综述

随着汽车工业的迅速发展,利用铝合金薄板替代汽车上钢材已成为汽车轻量化的一个必然趋势,而气垫炉漂浮技术是制约汽车用铝合金薄板生产的关键问题之一。目前关于气垫炉漂浮技术的研究较少,分别从气垫炉的简介及发展历史、漂浮技术的关键问题、气垫炉漂浮技术展望等几个方面对漂浮技术进行了评述。特别是针对漂浮技术的压力系数、流体与带材流固耦合、喷嘴与流场、带材漂浮高度和气垫炉设备等关键问题进行了分析,对未来的研究发展进行了展望。     

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).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

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.     

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.