基于VC的旋转电弧窄间隙MAG焊多信息融合焊缝跟踪系统

针对窄间隙旋转电弧MAG焊焊缝跟踪的需要以及单一传感器的不足,采用Visual C++开发了基于电弧传感和视觉传感的多信息融合焊缝跟踪系统。电弧传感采用NIPCI-6251数据采集卡、电流/电压传感器、电弧位置传感器结合NI的measurement studio软件,实现了对每个电弧旋转周期内电弧信号的获取,进而实现积分法、极值法、粗糙集等电弧传感方法。视觉传感利用图像采集卡、电弧位置传感器和CCD摄像机,获取电弧旋转到左右坡口侧时的焊接图像,实现焊缝偏差的检测。而焊缝跟踪是综合电弧传感焊缝偏差和视觉传感焊缝偏差的基础上进行焊缝纠偏。为提高系统运行效率,采用多线程方法实现电弧传感、视觉传感的同步采集和技术;利用CTimer控件实现焊缝偏差的多信息融合分析、显示和记录。系统的构建为进一步的多信息融合控制、焊接质量控制奠定基础。     

旋转电弧水下药芯焊丝电弧焊的智能化焊接系统

论述了基于旋转电弧传感的湿法水下电弧焊V形坡口焊缝跟踪技术.搭建了基于旋转电弧传感器的水下焊缝自动跟踪试验系统的硬件平台,确定了浅水水下湿法药芯焊丝焊接(FCAW))的工艺参数.利用焊接电流区间积分差值法进行焊枪水平偏差和竖直偏差的判别,通过数字信号处理来提高信号的稳定性、可靠性和一致性;通过理论和试验数据的分析,得到了水平和竖直方向的偏差判别方法;设计了模糊控制器和复合PID控制器,通过不同条件下的试验证明了以上工作的有效性.     

窄间隙CO2气体保护焊的磁控焊缝跟踪方法

针对单道多层窄间隙焊接中的焊缝对中和变侧壁宽度的侧壁融合的问题，建立了窄间隙CO2气体保护焊的电弧长度数学模型. 通过MATLAB仿真出电弧长度和焊接电流变化曲线，模拟焊接电流在两侧壁发生突变的特点，提出一种横向跟踪方法. 以1/4周期内电流变化斜率Ki>C的时间点作为电弧到达侧壁的标记，累计电弧从焊枪中心摆动到此时的脉冲数NL和NR，对NL和NR进行相关运算得到横向偏差信息，以数字电位计AD51113为基础设计了电磁传感器磁场强度调节装置. 结果表明，利用系统进行的焊缝跟踪效果良好，磁场调节效果稳定，为窄间隙CO2气体保护焊的跟踪提供一种新的解决方案.     

GMAW焊高速旋转电弧传感信号特征分析

电弧传感直接使用焊接电信号进行焊缝跟踪,旋转电弧还可用于改善焊缝成形,具有重要的应用价值.基于气保护熔化极焊接(GMAW)的数学模型以及焊丝端部的运动学模型,对旋转电弧传感的电流信号进行了模拟.在不同焊接参数下进行了焊接试验,采集了电流波形.结果表明,数值模拟结果与实际焊接电流波形吻合.电弧传感电流波形左右半周的不对称性与焊炬偏差成正比.电弧旋转频率越高,电流变化幅度越小.旋转半径越大,电流波形的不对称性越明显.研究结果对于高速旋转电弧传感系统的设计具有指导意义.     

基于数学模型的窄间隙MAG焊焊缝偏差分析

针对MAG焊焊缝跟踪过程中存在的焊缝偏差问题,建立基于粗糙集原理的窄间隙MAG焊焊缝偏差分析数学模型。偏差数学模型由数据采集、决策准则、数据预处理和模型简化四部分组成。基于数学模型的焊缝偏差分析不仅可以充分挖掘模型本身的信息,还具有直观性强和易于理解等优点。结果表明,利用所建立的数学模型能够有效地预测焊缝偏差,且具有较高的焊接定位精度。本研究对于焊缝偏差的识别和预测具有一定的指导意义,同时也为电弧控制器的设计提供了重要参考依据。     

一种用于焊缝跟踪的磁控电弧传感器

针对目前机械式电弧传感器普遍存在的易磨损、噪声大且稳定性差等问题,提出了将磁场控制电弧的技术应用于焊缝跟踪;设计了磁控电弧传感器,对其基本原理进行了详细阐述,并依据电磁场理论和磁控电弧规律分析了相关影响参数.对通过霍尔传感器获取的焊接电流信号采用了巴特沃思滤波器硬件滤波和小波分析的电流信号软件处理相结合的信号处理方法,对磁控摆动电弧、未加磁场电弧和机械旋转电弧三种情况下的实测电流信号进行了分析比较,应用有效区间双重去极值积分比较法提取实际焊缝坡口的偏差信息.结果表明,磁控电弧传感器用于焊缝跟踪正确可行,跟踪效果好,为目前对焊缝跟踪技术的研究提供了新的方向.     

侧向风场作用下横向焊接旋转电弧传感及焊缝跟踪

文中利用侧向风场的吹袭作用来抑制横焊熔池的下淌,研究了在侧向风场作用下焊缝成形质量和旋转电弧的传感特性. 提出了一种基于平面拟合的焊枪偏差和电极高度检测算法,实现了同一电流信号下焊枪偏差和电极高度的同时检测. 结果表明,适当控制侧风流量有助于抑制熔池下淌、改善焊缝成形. 但是随着风速的增加,焊接电弧的熄弧率升高、电弧传感的准确性降低. 针对焊接电流的噪声干扰,还设计了软阈值小波滤波算法,并开发了相应的模糊控制算法对焊枪偏差和电极高度进行调节,初步实现了横焊焊缝的成形控制和跟踪.     

磁控电弧传感器对埋弧焊熔宽的影响

以磁控电弧传感器模型为基础,建立了磁控电弧传感器焊缝跟踪系统的细丝埋弧焊熔宽数学模型.利用该数学模型研究横向交变磁场下焊缝熔宽的变化规律,选取模型中的主要参数进行焊接试验,得到励磁频率和励磁电流对焊缝熔宽影响规律曲线,并将仿真模拟结果与实际焊接试验结果进行比较分析.结果表明,熔宽随励磁电流的增大而增大,随励磁频率的增大而减小;模拟结果和实际焊接试验结果基本吻合,从而验证了所建模型的正确性,为磁控传感器和细丝埋弧焊焊缝跟踪系统的设计和开发提供必要的理论指导.     

改进的积分差值法在焊枪工作角检测中的应用

焊枪工作角的检测是改善焊接质量和实现焊缝跟踪的重要因素.文中首先建立了焊枪工作角和偏差变化与旋转电弧弧长变化的数学模型,并进行Matlab仿真;其次,介绍了焊枪工作角检测理论,通过采用对区间加权的焊枪电流积分差值法,从旋转电弧信号中获取反映焊枪姿态信息的特征值,最后,在理论推导和仿真的基础上,得到了焊枪工作角检测与焊缝偏差无关的结论.     

基于正交试验旋转电弧传感器焊缝跟踪工艺参数的优化

为了实现基于旋转电弧传感器的焊缝跟踪,并获得良好质量的焊缝,需要通过试验去确定最佳焊接参数。为了减少焊接试验的工作量、降低研制成本,采用正交试验设计法合理安排Q235钢板的机器人焊接工艺评定试验,以数理统计方法分析各焊接参数对焊缝质量影响的主次顺序。研究了旋转电弧传感器的旋转频率、焊炬高度、焊炬旋转半径和焊接电流四个主要影响因素对焊缝成形、电流信号特征和抗拉强度的影响,为后续的焊缝跟踪提供优化的焊接参数。     

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.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。