数字化焊接电源系统特征分析

现代焊接电源逐步走向数字化焊接电源，由于工作环境的特殊性，其实现相对困难。在此分析数字化焊接电源国内外发展现状和数字化电源的特点，针对目前研究的数字化TIG焊机详细介绍了其全部的结构组成，并根据研究过程中遇到的具体问题，总结了在实现数字化焊接电源过程中必需考虑的综合问题，并在此基础上，讨论了焊接电源控制的控制规律，提出了数字化综合系统平台的思想，指出了DSP(数字信号处理器)在数字化电源和数字化综合系统平台中的优越性和特殊性。     

弧焊电源焊接参数预置系统的发展

阐述了弧焊电源的发展历程,指出与传统的模拟电源相比,数字化弧焊电源的优势和在实际生产中存在的不足。在数字化电源的基础上介绍了弧焊电源焊接参数预置系统的研究现状,详细说明基于模拟电路、单片机、DSP及其他控制方法的预置系统,并分析基于各种控制方法的预置系统的优缺点。预测焊接参数预置系统的发展方向,应使其具有通用性,设计出不依赖于电源的独立焊接参数预置系统,一种预置系统可控制多类焊接电源。     

数字信号处理器DSP主控GMAW焊接

阐述了焊接过程信息数字处理控制思想，实际研究了数字信号处理器9DSP）在CO2气体保护焊机中的应用，将数字信号处理器（DSP）在送丝系统的柔性化调节，引弧和收弧模式，焊接参数的一元化自调节等方面的应用作了研究和试验，通过研究和样机试验，建立了一套焊接电源的数字化，信息化，柔性化控制平台，并探讨了数字信号处理器（DSP）在CO2焊接领域中的应用优点和前景，并提出了DSP主控GMAW焊接电源全系统框图，试验证明该系统工作稳定可靠，较好地满足了工艺性能，实现了焊机控制的数字化。     

基于ARM控制的多功能数字化逆变焊接电源

针对目前传统焊接电源存在的问题.主要讨论了多功能逆变焊接电源由模拟化向数字化改进的设计方法.介绍了硬件电路和软件系统的设计思路,包括如何用ARM处理器实现逆变焊接电源的数字化控制、主电路的设计、控制系统软件功能的设计和实现,最后对设计的样机进行了工艺试验.结果表明.基于ARM的数字化多功能逆变焊接电源具有较好的受控能力,能够满足高质量焊接的需要.     

基于CO2焊接系统的CAN总线设计

针对CAN总线技术在数据传输中具有实时性和灵活性等特点,并能构成分布式系统可靠性高和成本低等优点,设计了以CAN总线为通信,以ARM为控制芯片的数字化CO2焊接电源系统.编程实现了整个焊接系统的数字化控制.详细说明了CAN总线电路的设计、CAN总线的通信协议设计.对实现焊接系统的智能化控制具有一定的指导作用.     

数字化焊接电源系统的特征

介绍了数字化焊接电源系统的概念。分析总结了数字化焊接电源系统的特征和发展方向，提出了数字化焊接电源系统的主要研究内容。指出了数字化焊接电源系统交城为焊接电源的发展趋势。     

ARM处理器在焊接电源数字化控制系统中的应用

基于ARM处理器的弧焊电源的数字化控制,采用LPC2131控制器,通过不同特性控制与时序控制,使IGBT逆变式弧焊电源具有多功能的用途,主要可以实现手工焊、直流TIG、脉冲TIG和MAG焊等焊接方法.LPC2131主要用于不同焊接方法的时序控制、焊接给定参数与反馈参数的采样、PID和模糊控制算法的运算以及PWM的输出与调制控制,从而实现多功能焊接电源的数字化控制.提出基于嵌入式系统,实现焊接电源人机界面的优化、远程监控与多台焊接电源间的网络化的管理.     

基于倍福软PLC的多工位自动氩弧焊机

介绍散热器生产中氩弧焊机的自动化改造方案.系统采用智能数字化焊接技术、软PLC技术和伺服控制技术实现氩弧焊机在生产过程中的多工位自动控制和焊接.智能数字焊机能够实现电弧电流、焊接电流的数字化控制,提高了焊机的能源转换效率和焊接电弧质量.利用倍福TwinCAT软件实现一台PC机模拟四台软PLC技术,实现单主机多控制工位的设计.同时运用了先进的电子凸轮技术和伺服控制系统实现焊机的准确定位,有效克服了焊接过程中产生的误差,提高了氩弧焊机的焊接准确度.最后研究了装置控制系统的抗干扰问题.实际应用表明,该系统性价比高,安装和接线简单,易操作且控制精度高,大大提高焊接效率.     

数字信号处理器在CO2焊接中的应用

阐述了焊接过程信息数字处理控制思想。对数字信号处理器（DSP）在CO2气体保护焊机中的应用：送丝系统的柔性化调节、引弧和收弧模式、焊接参数的一元化自调节等方面进行了探讨。通过研究和样机试验，建立了一套焊接电源的数字化、信息化、柔性化控制平台，并探讨了数字信号处理器（DSP）在CO2焊接领域中的应用优点和前景。试验证明，该系统工作稳定可靠，较好地满足了工艺性能，基本实现了焊机控制的数字化。     

数字化弧焊逆变电源实时状态监测与管理

基于双数字信号处理器(DSP)的数字化弧焊逆变电源上,实现了嵌入式实时操作系统(RTOS)μC/OS-II (micro controller operating system-II)的成功移植和应用.在对焊接过程中的众多事务进行功能明确的任务划分、多任务调度、多状态监测的基础上,实现了对电源工作状态的实时监控以及对电源的输入输出模块、逆变模块和焊接外设等故障做出快速准确的判断和保护处理,保障了焊接电源的工作可靠性和安全性.并且通过多任务协调配合,实现了各个工作状态与用户的实时友好交互,提高了电源系统的故障准确辨识率及其可操作性,解决了弧焊逆变电源实时状态以及整机的数字化综合管理问题.     

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.     

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.