基于双目视觉的机器人快速示教系统

针对工业机器人传统示教方式存在示教难、示教慢的问题,基于双目视觉提出构建机器人快速示教系统。该系统将双目视觉模块固接在机器人末端工具上,减小示教范围限制;设计出一种带有特征板和位姿测量杆件的手持示教装置,用于对设定点进行快速位姿示教;采用最小二乘法实现特征板到位姿测量杆件末端的平移参数标定。该系统通过双目视觉模块采集手持示教装置特征板图像,并进行图像处理获得末端点的位姿信息;将该位姿信息转换到机器人基坐标系下,实现机器人示教再现。搭建川崎RS010NA六自由度工业机器人的双目视觉快速示教系统,进行空间25点的示教复现测试,机器人示教复现位置平均误差为2.427 mm;采用移动示教后,平均位置误差下降25.3%;测试结果表明该系统具备可行性,且移动示教可以提高示教复现精度。     

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。     

焊接自动线和焊接机器人

用于球罐焊接的柔性导轨焊接机器人研究 针对大型球罐焊接的工程实践,开发出系列柔性轨道焊接机器人,实现球罐的全位置多道多层焊接;并针对研制过程中的难点对焊接机器人锁紧机构的设计、在线焊缝轨迹示教、在线全位置焊接参数控制、自主学习开放式专家系统进行详细说明。实践证明,该柔性导轨焊接机器人能够较好地完成复杂工件的多种焊缝的现场焊接,尤其是球罐全位置焊接的工艺要求。     

焊接自动线和焊接机器人

用于球罐焊接的柔性导轨焊接机器人研究 针对大型球罐焊接的工程实践,开发出系列柔性轨道焊接机器人,实现球罐的全位置多道多层焊接;并针对研制过程中的难点对焊接机器人锁紧机构的设计、在线焊缝轨迹示教、在线全位置焊接参数控制、自主学习开放式专家系统进行详细说明。实践证明,该柔性导轨焊接机器人能够较好地完成复杂工件的多种焊缝的现场焊接,尤其是球罐全位置焊接的工艺要求。     

用于球罐焊接的柔性导轨焊接机器人研究

针对大型球罐焊接的工程实践,开发出系列柔性轨道焊接机器人,实现球罐的全位置多道多层焊接;并针对研制过程中的难点对焊接机器人锁紧机构的设计、在线焊缝轨迹示教、在线全位置焊接参数控制、自主学习开放式专家系统进行详细说明.实践证明,该柔性导轨焊接机器人能够较好地完成复杂工件的多种焊缝的现场焊接.尤其是球罐全位置焊接的工艺要求.     

基于激光视觉的薄板焊缝跟踪方法研究北大核心

由于示教型焊接机器人在进行汽车薄板件连续焊工艺时存在装夹误差和热变形等问题,导致焊缝实际轨迹与示教轨迹存在较大误差。为提高焊接质量,基于焊接机器人构建激光视觉焊缝检测跟踪系统,提出基于目标估计准则的焊缝跟踪算法,实时跟踪焊缝中心点三维位置变化。以传统图像处理法提取初始帧焊缝特征点,通过改进的孪生神经网络对强干扰下的焊缝特征点进行跟踪提取。通过坐标转换得到机器人基坐标系下的焊缝中心特征点三维坐标。结果表明:该算法能精确提取跟踪焊缝特征点,平均误差为0.48 mm,平均帧率为90帧/s,优于传统图像处理方法和基于相关滤波的方法,能够实现快速准确的跟踪。     

遥控焊接力觉遥示教点间变迁控制技术

在遥控焊接力觉遥示教过程中,为实现遥控焊接自主遥示教,需要对遥示教点间状态变迁技术进行基础研究.根据焊缝辨识模型,确定示教点位置,通过共享技术调整好示教点的姿态,辨识记忆好第一个焊缝示教点,向下一个示教点变迁控制,主要包括示教点z方向变迁控制和示教点在xSy平面内方向变迁控制.并对摩擦力对遥示教点间变迁影响进行分析,证明了摩擦力的存在会在xSy平面内减小机器人进给计算量,在z方向使Fz增加,但是在遥示教自适应控制准许范围内,不会影响焊缝辨识逻辑.通过遥示教变迁控制技术,实现了遥示教点间自动变迁,为自主遥示教创造条件.     

钢结构全位置焊接机器人的研究与开发

介绍了一组适用于钢结构焊接的GDC型全位置焊接机器人.该焊接机器人具有在线焊缝轨迹示教、在线全位置焊接参数示教、离线焊接参数设置等智能控制手段,可适应不规则焊缝的轨迹跟踪,实现多层多道焊及全位置焊的自动化焊接,并可灵活方便地完成多台焊接机器人的焊接参数设置.GDC-1型焊接机器人已成功应用于"奥运鸟巢工程"现场焊接,可在建筑铜结构焊接工程中推广应用.     

焊接自动线和焊接机器人

钢结构全位置焊接机器人的研究与开发;焊接机器人的初始焊接位置视觉导;基于轨迹编程的示教式焊接机器人控制技术;三相低频焊机主电路的控制模型与软件流程;不锈钢钎焊管理信息系统的开发     

焊接自动线和焊接机器人

钢结构全位置焊接机器人的研究与开发;焊接机器人的初始焊接位置视觉导;基于轨迹编程的示教式焊接机器人控制技术;三相低频焊机主电路的控制模型与软件流程;不锈钢钎焊管理信息系统的开发     

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.     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.