冷轧薄板闪光对焊机电源控制系统

从冷轧薄板酸洗生产线中闪光对焊机的电源控制系统入手,具体分析了其硬件结构和在闪光阶段、项锻阶段的控制方法,重点对在闪光前期、闪光后期和顶锻时期焊接变压器二次侧电压和晶闸管导通角的改变情况进行了研究.生产实践证明,应用了该电源控制系统的闪光对焊机很好地满足了冷轧薄板的对焊技术要求.     

冷轧薄钢板专用闪光焊机控制方法

针对冷政薄钢板生产的特点,设计了冷轧薄钢板专用闪光焊机的总体结构.分析了冷轧薄钢板专用闪光焊机控制系统,包括冷轧薄钢板闪光焊机动夹具送进速度的控制,动夹具位置的控制以及顶锻控制.动夹具送进速度控制曲线由动夹具送进速度分量函数、灵敏度分量函数和焊接电流分量函数构成.动夹具位置的控制是根据不同的闪光模式,计算出动夹具的位移函数,借助动夹具的位移函数来控制动夹具的运动位置.通过控制焊接时动夹具位置来实现顶锻过程.     

基于DSP的无头轧制专用焊机电源的数字化设计

介绍了一种基于数字信号处理器(DSP)控制的无头轧制专用焊机电源的研制.具体讨论了DSP芯片控制焊机电源的硬件电路设计,重点介绍了闪光焊机电源主回路的数字同步和触发电路、控制电路的键盘和显示、保护电路等.提出了DSP控制的无头轧制专用焊机电源信息控制思想,建立了焊机电源数字化、信息化、柔性化的平台.试验表明,该焊机电源能够满足无头轧制系统中时闪光焊机的大电流低电压的工艺要求,实现了焊机控制的数字化.     

我国固定式钢轨闪光焊机发展与应用

在我国16个长钢轨焊接基地中,大部分生产线采用了GAAS80系列钢轨闪光焊机,另有成都铁路局、广铁集团等单位的焊轨基地生产线采用了少量K系列固定式钢轨闪光焊机。本文介绍了我国长钢轨焊接基地应用的几种固定式钢轨闪光焊机和我国自主研发的固定式钢轨闪光焊机,详细分析了各型焊机的历史发展、技术参数、机械结构、电源系统和工艺特点。结合我国当前铁路发展的趋势,未来固定式钢轨闪光焊机将朝自动化、智能化和信息化方向发展。     

液压技术——在闪光焊机上的应用

闪光焊机是冷轧带钢厂的一台重要设备。它主要布置在酸洗线入口处,将热轧来的钢卷焊接起来,使带钢进行连续酸洗。一九八二年八月在太钢第六轧钢厂,对1700闪光焊机进行焊接工艺考验。对不同厚度的带钢连续焊了百多条焊缝,其中     

数字化闪光焊机的研制

介绍了一种由80C196KB单片机构成的全自动焊机数字控制系统的软、硬件设计.焊接电源采用六相半波晶闸管整流电路,焊机外特性的控制是通过电压反馈方式进行数字PI调节完成.在连续闪光过程控制时采用电液伺服阀实现了对闪光曲线的控制,通过串行通信接口与焊接电源系统交换数据.在控制过程中的参数采集均通过光电隔离,避免了大功率焊机在焊接过程中的电磁干扰对控制系统的影响.     

基于Simulink的大功率闪光焊机的电源仿真

针对大截面钢坯闪光焊接的特点,分析了大功率闪光焊机电源的工作原理,其主电路采用变压器初级调压、次级整流的拓扑结构.建立了基于Simulink功率模块的具有非线性特征的主电路模型和动态电阻负载模型.动态电阻主要由焊件的电阻和焊件端面之间的接触电阻组成.仿真结果表明,建立的主电路模型和动态电阻负载模型能够较为真实地模拟闪光对焊的动态过程,推动了大功率闪光焊机电源系统的数字化建模和仿真的研究水平.     

基于模糊PID的闪光焊机液压系统的压力同步控制研究

介绍了闪光焊机的液压系统的组成及其工作原理,建立了闪光焊机液压系统的数学模型。针对闪光焊接的顶锻阶段,提出了一种基于二级模糊自调整PID的控制模型,第一级模糊PID控制应用于基准通道,第二级模糊PID控制应用于同步通道,实时地调整PID参数以达到系统的同步运动,该控制方法有效减少了两个系统的压力动态同步误差。     

基于遗传算法的无头轧制技术闪光焊机行走系统

介绍了无头轧制闪光焊机的行走系统的组成及其工作原理,建立了闪光焊机行走系统的数学模型.提出了一种基于遗传算法和神经网络PID相结合的控制方法,该算法用GA(遗传算法)优化BP网络的初始连接权系数,得到一组较佳的BP网络初始权值的参数组合,再通过BP算法,实现PID参数的在线调整.仿真结果表明,经过GA对网络初始权值优化后,闪光焊机行走系统的输出响应能够快速的跟踪输入的信号,使系统具有精确的同步性能.     

程序控制晶体管焊接电源

本文介绍 TP801—Z80单板微型计算机控制晶体管焊接电源的硬件结构及其操作原理。同其它控制方法相比,电路功能多,设计简单,安装调试不复杂,特点是通过软件的修改,就可以改变控制系统的结构和性能。可用于各种脉冲的 TIG、MIG 焊,等离子脉冲焊以及 CO_2短路过渡焊接。使许多专用自动焊机的控制和电源通用化,缩短专用自动焊机的研制周期,降低研制成本。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.