盾构机焊接/切割机器人研制

针对盾构机盾体结构复杂、焊接耗时长这一问题,设计了全自动焊接/切割机器人。该机器人同时具备焊接/切割功能,能够进行多层多道自动焊接,并满足焊缝自动切割要求;焊接机器人控制系统具有横焊、平焊、立焊三种位置的焊接数据库,每个数据库中层数、道数可灵活设置;具有坡口规划和轨迹存储功能,实现不规则坡口的多层多道自动焊。利用所研发的焊接/切割机器人进行盾体自动焊接及切割试验,试验结果表明,该机器人能够满足盾构机盾体焊缝自动焊接及切割要求。     

面向盾构机制造的移动式焊接机器人的研制

针对盾构机盾体焊接特点研制了适用于盾构机焊接的移动式焊接机器人系统。根据机器人焊接作业需求,设计成分体式结构,焊接机头小巧,方便搬运及安装。该焊接机器人适用于横焊、平焊、立焊3种位置焊接模式,并可以对不同的焊接过程参数进行分类管理;具有多层多道焊的"坡口规划"及焊缝示教等功能,可满足盾构机厚板多层多道自动化焊接。利用研制的移动式焊接机器人在盾构机制造现场进行工艺焊接试验,试验结果证明,该移动式机器人能够满足盾构机盾体厚板焊缝自动焊接要求。     

基于KUKA弧焊机器人的盾构机关键部件焊接工作站

针对盾构机关键零部件的焊接特点,基于KUKA弧焊机器人研制了自动化焊接工作站。利用焊接机器人接触寻位、多层多道焊和电弧跟踪等功能实现盾构机联体刀座工件的自动焊接。焊接实验结果表明,所研制的盾构机关键零部件焊接工作站能够满足离散制造企业的零部件小批量自动化焊接生产。     

厚板弧焊机器人自定义型焊道编排策略

多层多道焊路径的自动规划是实现厚板机器人焊接的关键技术之一.对典型的单面V形和双面K形坡口多道焊路径规划策略进行了研究,建立了基于图形多层多道焊离线规划模块,通过特征建模、焊接顺序、焊道参数及规划类形等设置,系统可自动生成多层多道焊路径的位置和姿态,重点推导了自定义型多道焊路径规划策略,并对单面V形坡口多层多道S形焊缝进行自定义型路径规划,实现了机器人多道焊的仿真和运动程序的快速生成,提高了示教灵活度和效率.     

基于机器人的多层多道马鞍形焊缝自动焊接应用研究

针对含盆形坡口的马鞍形焊缝的多层多道焊,研究了一种基于工业机器人的自动化焊接方法,包括机器人运动轨迹规划、焊道排布、焊枪姿态设定、焊接参数设定、起弧收弧优化、自动排道软件设计等具体内容,并且针对3种不同规格的工件进行了焊接试验。试验结果表明,该方法能充分保证焊接质量和成形效果,同时还具有广泛的适用性。     

钢结构数字化全功能焊接机器人研制

针对钢结构复杂现场的自动化焊接作业需求,开发出四自由度移动焊接机器人.在机械方面进行了小型化、轻量化、模块组合化的设计,解决现场高空作业的快速安装调试和高空搬运的需求;在控制方面,采用焊缝再现示教、参数管理专家数据库、坡口规划数据库等技术,解决野外作业的坡口轨迹跟踪、焊接参数和电源参数的协调控制、大厚钢板坡口自动排道的多层多道焊接等实际问题,并进行了大量焊接试验、工艺评定和产业化推广,建立样板工程.结果表明,所开发的机器人实现了真正意义的钢结构数字化全功能焊接,机器人结构简单轻便、自动化程度高、焊接成形好,焊接质量满足工艺要求,适合于现场安装焊接作业.     

中厚板V形坡口多层多道焊机器人焊接技术研究

针对采用在线示教方式的中厚板V形坡口多层多道焊机器人焊接工艺进行了研究,结合机器人程序中的偏移指令设计了一种新的多层多道焊机器人焊接方法。通过对机器人焊接顺序、焊接路径进行规划,利用简化的焊道截面计算出各个目标点的偏移量,完成对机器人程序的编写。利用机器人离线编程软件Robot Studio以及实际的焊接设备对所提出的方法进行了试验验证。结果表明,该方法可有效减少示教次数,提高焊接效率,焊接后的V型坡口板填充效果以及焊缝成形良好。     

移动式焊接机器人在港珠澳大桥钢主梁大节段中的应用

目前钢箱梁节段组焊仍以手工焊为主,自动化程度低。针对港珠澳大桥组合梁钢主梁节段制作及总拼焊接自动化需求和特点,本公司定制了一种轨道式的移动焊接机器人,具有无盲区焊接、喇叭口焊接等自动焊接功能。针对常用的钢梁焊接形式,开展了立焊、立仰焊、横焊等多种不同工况以及标准坡口和喇叭口等不同坡口形式的机器人自动焊接试验,试验所焊焊缝外观成形和内部质量均符合规范要求。该移动式焊接机器人已在港珠澳大桥组合梁钢主梁中山总拼现场大范围应用,焊缝一次探伤合格率达到99.64%,与手工焊相比,生产效率提高50%,人工成本降低50%,取得了很好的经济和社会效益,可供类似项目借鉴。     

机器人自动脉冲TIG焊J形坡口焊缝填充策略

核电压力容器封头由半球形封头和多个圆管相贯构成,连接的焊缝为J形坡口,轨迹是球管相贯的空间曲线,位于封头内部.由于该焊缝的特殊性,目前普遍采用手工焊接,质量与效率不佳.文中针对核电压力容器封头J形坡口的机器人自动焊接技术提出了一种多层多道焊填充策略.通过焊接结构分析,确定了J形坡口的焊接工艺分区,提出了设定焊接层数、道数的焊接轨迹规划方法,进而提出了焊接工艺参数的设定规则并据此对焊缝形状进行控制.结果表明,应用文中提出的焊缝填充策略及焊缝形状控制方法可获得良好的焊缝成形.     

基于激光传感器的机器人自适应多层多道焊接

针对机器人自动化焊接过程中工件的定位误差、加工误差和激光传感器的安装误差的问题,提出了一种基于线结构视觉激光传感器获取焊缝形状位置信息,并使机器人能够自动调整焊枪位置和姿态来修正误差,同时自适应不同角度焊缝的多层多道路径规划方法。首先进行手眼标定,采用pyqt5在windows系统环境下部署焊接机器人手眼标定软件,把焊道空间点信息从视觉坐标系转换为机器人基坐标系下。然后对工件进行扫描,通过预设定算法完成对实际坐标点的预处理计算,并自适应调节工具坐标系的位姿弥补偏差;最后根据处理得到的焊缝坡口的特征参数和焊接工艺要求,规划多层多道焊接的路径完成焊接。对中厚板碳钢单边V形坡口进行试验,结果表明,该方法具有良好的实用性。     

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。