基于HNC的液压同步控制实验台构建

针对大型液压机液压系统的多液压缸同步运动问题,提出了使用HNC实现精确同步控制的解决方案。阐述了液压实验台控制原理以及其硬件、软件构成。该方案控制系统实现了液压实验平台的正常运行,通过实验数据分析,基于HNC的液压同步控制系统同步精度为0.05 mm,稳态误差小,且简单易用。     

基于HNC的液压同步控制实验台构建

针对大型液压机液压系统的多液压缸同步运动问题,提出了使用HNC实现精确同步控制的解决方案.阐述了液压实验台控制原理以及其硬件、软件构成.该方案控制系统实现了液压实验平台的正常运行,通过实验数据分析,基于HNC的液压同步控制系统同步精度为0.05 mm,稳态误差小,且简单易用.     

支架试验台四缸同步控制系统的设计

液压支架试验台在工作中受液体压缩、泄漏、阻尼等的影响,特别是受外载力的时变性及运动行程较大等因素的影响,实现多个液压缸的高精度同步控制有很大难度。以液压支架试验台升降液压缸系统为研究对象,分析升降液压缸的工作状态和运动特性,提出一种采用电液比例阀实现四缸同步控制的设计方案,采用主从式的控制策略,并建立系统的同步控制数学模型。MATLAB仿真和实验结果显示:该控制系统有很好的同步性,基本上满足目前液压支架试验台的同步精度要求。     

基于LabVIEW的双液压缸同步控制系统的开发

针对液压缸同步要求,构建了基于Lab VIEW的实时采集控制系统。该系统利用采集卡实现了对主、从液压缸位移的实时检测,通过增量式PID结合控制卡实现了对从液压缸位移的闭环控制,从而保证了从液压缸对主液压缸的实时跟踪,达到同步控制的目的。测试结果表明:该控制系统能够很好地控制主、从液压缸的位移,同步精度高,完全符合实际使用需求。     

万吨液压机五缸同步控制系统设计

在液压传动系统中,同步控制要求非常普遍,但大流量、高精度、多执行器同步,一直是一个较难解决的问题.由于液压系统的液体压缩、泄漏、阻尼等特点,尤其是在外载力较大和外载力不断变化及设备本身的不平衡与设备运动行程较大的因素下,实现多个液压缸较高的同步精度有很大难度.文中介绍了采用模糊控制和PID控制相结合的方法,对万吨液压机的五缸同步控制系统进行了设计,经实验证明,该控制方法对该液压机的五缸同步控制是成功的.     

基于HNC的四角调平液压实验台构建和分析

针对大型液压机等液压系统的多液压缸同步运动问题,提出了使用HNC实现精确同步控制的解决方案。阐述了液压实验台控制原理以及系统硬件、软件构成。该系统实现液压实验平台的正常运行,分析了实验所得数据。实验结果表明HNC在液压控制系统中应用精度很高。     

基于灰色预测理论的双液压缸同步控制研究

为解决双液压缸协调同步控制问题,根据灰色预测理论,设计了灰色预测前馈控制器。研究典型的双液压缸同步系统,并在此基础上建立了单液压回路前馈控制器和双缸同步系统灰色预测控制器。实验结果表明：在灰色预测控制下的液压缸工作曲线平滑,液压缸工作稳定。在所设计的极端实验中,两液压缸运动误差能够控制在15 mm以内,验证了基于灰色预测理论的双液压缸同步控制设计的可行性。     

基于状态重构理论的液压系统的同步控制

为了解决多液压缸伺服机构在联合驱动时的同步控制精度问题,提出了一种基于状态重构理论的液压伺服系统同步控制方法.仿真实验结果表明,该方法可以快速地实现多液压缸的同步控制,在半物理仿真实验系统上也得到了相同的结果.     

舞台升降液压泵控缸同步控制系统研究

研究重型升降舞台同步控制系统,该闭环同步控制系统以比例变量泵作为控制元件,以非对称液压缸为输出元件,以位移传感器作为反馈元件,实现对输出位移的同步控制.建立该泵控缸系统的数学模型,以MATLAB/SIMULINK为开发工具,建立仿真模型并进行仿真分析.结果表明该控制系统能满足重型舞台同步升降控制的要求,系统简单且节能.     

Fuzzy-PID控制在80MN液压机同步控制系统中的应用

在液压传动系统中,同步控制要求非常普遍,但大流量、高精度、多执行器同步,一直是一个较难解决的问题.由于液压系统的液体压缩、泄漏、阻尼等因素影响,尤其在大行程、大负荷情况下,实现多个液压缸高精度同步有很大难度.为此,采用模糊PID控制技术对液压机同步控制系统进行设计.实际应用表明:该系统具有运行稳定、同步精度高、性能良好等特点.     

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.     

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.