基于机器视觉的多类型工件测量系统研究

综合应用光电技术、数字图像处理技术和计算机技术,以薄片型机械零部件为主要测量对象,开发-套工件尺寸测量系统,主要包括照明系统、图像采集系统、图像处理系统和尺寸测量系统.根据检测要求,采用Canny算法进行边缘检测粗定位和8个方向模板的改进亚像素检测技术获得工件精确轮廓信息,再对轮廓进行分割和选择,采用Hough变换完成...     

基于LabVIEW的图像识别系统在油泵焊接生产线中的应用

随着计算机等相关技术的发展,图像处理技术越来越多地应用于焊接工业生产质量监控中。利用基于LabVIEW技术的图像处理软件IMAQVision,对被测工件图像进行图像增强、模版匹配、二值化处理、形态学处理等一系列图像处理及图像识别,从而设计出可以在线检测柴油机油泵锁紧垫片安装质量的目标图像识别系统。实验结果表明,设计的系统完成了预定目标,有较好的实际应用价值。     

基于图像处理的数字刀具测量仪实验研究

研究了一种基于数字图像处理技术的高精密刀具测量仪。仪器使用红色LED光源垂直照射被测刀具,CCD数码相机采集刀具图像并转换成数字信号,通过通用串行总线接口传入计算机并由数字图像处理软件进行处理。图像处理软件采用一种改进的自动调焦算法实现大范围快速调焦,采用一种新的相机标定方法求解精确的标定参数,采用一种复合型亚像素边缘检测算法提取刀具边缘。仪器具有精度高和自动化程度高等优点,为数控加工中心的高精密加工提供了保证。实验结果证明:仪器的重复性测量精度可达3μm。     

图像增强型X射线工业电视系统工艺参数优选与系统灵敏度提高

在仅有图像增强器而不具备数字图像处理单元的Ｘ射线工业电视系统上，进行各种工艺参数的实验优选，并采用选择小焦点射源，散射屏蔽等措施，提高系统检测灵敏度。实验证明，系统检测灵敏度可以高速提高到小于２％，使图像增强型Ｘ射线工业电视系统成功地应用于液化石油气钢瓶焊接生产线。     

基手LabVIEW的图像识别系统在油泵焊接生产线中的应用

随着计算机等相关技术的发展，图像处理技术越来越多地应用于焊接工业生产质量监控中。利用基于LabVIEW技术的图像处理软件IMAQVision，对被测工件图像进行图像增强、模版匹配、二值化处理、形态学处理等一系列图像处理及图像识别，从而设计出可以在线检测柴油机油泵锁紧垫片安装质量的目标图像识别系统。实验结果表明，设计的系统完成了预定目标，有较好的实际应用价值。     

基于立体视觉的坐标网格分析法

坐标网格分析法作为一种物理模拟技术 ,已在金属塑性成形的生产中被广泛应用 ,但传统的手工测量方法存在工作量大和精度低的缺点。该文针对板料成形中常用的三维圆形坐标网格系统 ,提出一种新的基于图像处理和立体视觉技术的网格应变自动测量分析方法 ,并开发了相应软件 ,成功地测绘出变形工件的应变等值线图和板料成形极限图。实验结果表明 ,该方法可以使板料应变的测量速度和精度均得到提高     

基于数字图像处理技术的溶渣泡沫高度检测方法

提出一种基于数字图像处理技术的溶渣泡沫高度检测方法。该方法由CCD摄像头将采集到的溶渣泡沫影像经图像采集卡转换成数字图像,然后由计算机经图像处理后得到溶渣泡沫的轮廓线,并由轮廓线背景的刻度线直接得出溶渣泡沫各处的实际高度。实验结果表明,该检测原理可行,对实现溶渣泡沫高度的在线检测具有指导意义。     

金属零件熔积成形过程形状质量的可视化诊断

利用单目视觉技术进行熔积成形过程监测;借助数字图像处理技术对熔积层形貌信息进行处理获得熔积层的宽度信息;以图像处理获得的熔积层缺陷点像素坐标为源头,通过文中建立的空间定位数学模型还原其三维空间位置信息,最后进行熔积层检测试验.结果表明,文中提出的单目视觉定位数学模型和数字图像处理算法能够准确的对熔积层宽度进行非接触地实时监测,并能够对可能出现的缺陷点进行快速的识别与准确的定位.因此文中方法能够实时调整与优化快速成形过程中的熔积工艺参数,保证制件形状与尺寸精度.     

液压油污染度CCD显微检测系统

研制了一种新型液压油污染检测系统.采用柯拉远心光路照明原理,使被测油液得到充分均匀照明.综合CCD光电显微成像和计算机数字图像处理技术,运用最佳阈值分割和轮廓提取相结合的图像数据处理方法,实现了污染颗粒图像边缘的精确检测.对实际液压油进行抽样实验,其测试精度达到国际标准的要求.     

油液监测技术中磨粒图像处理的研究进展北大核心

对油液监测技术中的磨粒图像特点深入分析,在此基础上,总结磨粒图像处理的方法,包括磨粒图像的模糊图像恢复、图像去噪、图像分割、磨粒特征提取。分别阐述了这4种方法在处理磨粒图像时能够达到的实验结果、遇到的一些问题及解决方案,得出在模糊图像恢复和图像去噪的基础上可以更好地完成图像分割,进一步可更好地完成磨粒特征提取,概述了运用这4种方法在机械磨损状态监测中可帮助了解机器的磨损状态、磨损程度、磨损部位、磨损类型等。结合目前的工作进展,总结磨粒图像处理技术的发展进程,提出磨粒图像处理技术仍然是状态监测中一项具有挑战的课题,并对磨粒图像处理技术的各个方向提出相应的展望。     

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.