Optimizing loading path and die linetype of large length-to-diameter ratio metal stator screw lining hydroforming

In order to meet the high temperature environment requirement of deep and superdeep well exploitation, a technology of large length-to-diameter ratio metal stator screw lining meshing with rotor is presented. Based on the elastic-plasticity theory, and under the consideration of the effect of tube size, material mechanical parameters, friction coefficient and loading paths, the external pressure plastic forming mechanical model of metal stator screw lining is established, to study the optimal loading path of metal stator lining tube hydroforming process. The results show that wall thickness reduction of the external pressure tube hydroforming(THF) is about 4%, and three evaluation criteria of metal stator screw lining forming quality are presented: fillet stick mold coefficient, thickness relative error and forming quality coefficient. The smaller the three criteria are, the better the forming quality is.Each indicator has a trend of increase with the loading rate reducing, and the adjustment laws of die arc transition zone equidistance profile curve are acquired for improving tube forming quality. Hence, the research results prove the feasibility of external pressure THF used for processing high-accuracy large length-to-diameter ratio metal stator screw lining, and provide theoretical basis for designing new kind of stator structure which has better performance and longer service life.

Construction of Solidus Lines of Binary Metal Systems Having a Low Solubility of Components in the Solid Phase

The paper presents the calculation results on the construction of solidus lines of phase diagrams for some binary metal systems based on cadmium, zinc and tellurium. The investigations have been carried out using the phase equilibrium thermodynamics and known liquidus lines. By the calculation method the solidus lines of phase diagrams of the Cd-Na, Cd-Tl, Te-Ga, Te-As, Te-Cu and Zn-Sn systems were constructed in the temperature range from the base component melting point to the eutectic transformation temperature. In the Cd-Tl, Te-As, Te-Cu and Zn-Sn systems a retrograde solubility of the second component in the solid phase was observed. The temperature and maximum solubility values at the retrograde behavior of solidus lines, as well as, the limiting solubility values of components at eutectic transformation in the systems based on Cd, Zn and Te were determined.

A cluster line approach to finding new Fe-B-Y-Nb-Zr bulk metallic glasses

The glass forming ability of the [(Fe12/13Y1/13)100?xBx]96Nb2Zr2 (x=9–26) system was investigated using a series of cluster lines. Three types of clusters, an icosahedron (Fe12Y), a capped Archimedes anti-prism (Fe8B3) and a capped trigonal prism (Fe9B), as well as a binary eutectic (Fe83B17) were considered. Bulk glassy alloy rods of 3 mm in diameter were synthesized using a copper mold suction-casting method. The glass transition temperature was observed for all samples in the boron range of 15.9at%-25.7at%, with the alloy at 15.9at% of boron having the best thermal properties. The ferrous-based bulk metallic glasses (BMG) obtained have high reduced glass transition temperatures with the maximum reaching 0.63 and large supercooled liquid regions with the maximum reaching 111 K. Magnetic testing revealed a large value of coercive force and remanent magnetization, being 11 kA/m and 0.1 T, re- spectively.

Signal processing for real-time identification of similar metals by laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy(LIBS) is regarded as a promising technique for realtime sorting of scrap metals due to its capability of fast multi-elemental and in-air analysis. This work reports a method for signal processing which ensures high accuracy and high speed during similar metal sorting by LIBS. Similar metals such as aluminum alloys or stainless steel are characterized by nearly the same constituent elements with slight variations in elemental concentration depending on metal type. In the proposed method, the original data matrix is substantially reduced for fast processing by selecting new input variables(spectral lines) using the information for the constituent elements of similar metals. Specifically, principal component analysis(PCA) of full-spectra LIBS data was performed and then, based on the loading plots, the input variables of greater significance were selected in the order of higher weights for each constituent element. The results for the classification test with aluminum alloy, copper alloy,stainless steel and cast steel showed that the classification accuracy of the proposed method was nearly the same as that of full-spectra PCA, but the computation time was reduced by a factor of 20 or more. The results demonstrated that incorporating the information for constituent elements can significantly accelerate classification speed without loss of accuracy.

Resolution of an esophageal leak and posterior gastric wall necrosis with esophageal self-expandable metal stents

The use of weight reduction surgeries has increased over the years with a higher proportion of these surgeries being sleeve gastrectomies,this has been associated with some complications including staple line leaks.We report a 32-year-old male who had undergone a laparoscopic gastric band surgery and subsequently a laparoscopic sleeve gastrectomy,this was complicated by both an staple line leak at the gastroesophageal junction as well as a large(> 4 cm) posterior gastric wall defect due to gastric wall necrosis. We used two co-axially inserted self-expandable stents(SEMS) in the management of this patient,5 stents were used over repeated endoscopy sessions and 20 wk. Both defects had resolved without the need for surgical intervention.This is the first reported case were SEMS are used for both a staple line leak as well as a gastric wall defect.We also review the literature on the use of SEMS in the management of leaks post weight reduction surgeries.

特高压GIL绝缘子用微米氧化铝-氧化硅共混环氧复合材料的性能研究

特高压气体绝缘金属封闭输电线路(GIL)电压等级高、输送容量大,对绝缘子耐受电、热、力综合作用能力的要求更高。本研究通过分别掺杂微米级氧化铝、氧化硅和氧化铝-氧化硅共混填料的方式制备了环氧复合材料,对共混体系力学、热学和电气性能等进行测试分析。结果表明:随着氧化铝填料体积占比的提高,复合材料的综合力学性能提升,微米氧化铝/环氧复合材料综合力学性能最佳。掺杂两种填料有助于提升共混体系的导热和耐电弧性能,但会略微降低玻璃化转变温度和增大热膨胀系数,当氧化铝和氧化硅填料体积比为1∶1时,复合材料的耐电弧时间可达186.63 s,导热系数可达1.198 W/(m·K)。随着氧化硅填料体积占比提高,环氧复合材料的介电常数减小,电气强度升高,体积电阻率增大,介质损耗减小。微米氧化硅/环氧复合材料工频电气强度最高,可达36.63 kV/mm。

Glass formation of ternary Sm-based Sm-Al-Co bulk metallic glasses

Ternary Sm-based Sm-Al-Co alloys at specific compositions designed using an e/a- and cluster-related criteria exhibit high glass forming abilities and form bulk glassy rods of 3 mm in diameter by a copper mold suction-casting method. Four composi- tions of bulk metallic glasses (BMGs) are Sm50Al25Co25, Sm52Al24Co24, Sm54Al23Co23 and Sm56Al22Co22, which all satisfy a constant conduction electron concentration of 1.5. Among them, the BMG exhibiting the largest reduced glass transition temperature (Trg) is Sm50Al25Co25, which reaches 0.648. The glass transition temperature Tg and the onset crystallization temperature Tx of this alloy are respectively 579 and 640 K at a heating rate of 20 K/min.

面向钣金混流生产线的仿真优化研究

文章以某电梯钣金加工公司的钣金混流生产线为背景,通过虚拟仿真方法对钣金生产环节中的投产序列和瓶颈问题进行优化。首先,根据某电梯门板生产线的实际生产状况,建立生产线的仿真模型,以工件完工时间、设备空闲时间和设备总切换时间为目标,基于遗传算法,优化钣金混流生产线的投产序列;其次,通过分析缓存区添加位置和容量对钣金生产线产量的影响,解决生产线堵塞、利用率不平衡等问题。结果表明,对生产线的优化有效,经优化后的投产序列相比原始投产序列整体时间缩短约15%,通过适宜的缓存区设置,各工位设备平均利用率提高了9.6%,产量提高了14.15%。

耐火材料的抗碱侵蚀性研究进展

碱侵蚀是高炉、回转窑、匣钵等高温装置重要部位损毁的主要原因,不同于熔渣导致的溶解侵蚀和物理冲刷导致的蚀损,碱侵蚀有着其特殊的作用机制。本文首先介绍了碱的物理性质并计算了其与耐火氧化物反应的吉布斯自由能和体积效应,以此为出发点综述了碱对典型高温装置关键部位的侵蚀过程及机制,并概述了碱性耐火材料、铝硅系耐火材料、非氧化物耐火材料、新型合成材料抗碱侵蚀的研究与应用新进展,同时对比了几种国内外抗碱侵蚀标准或方法,最后对耐火材料抗碱侵蚀性研究提出了几点建议。

输电线路短路电流对埋地管道电位抬升及抑制方法研究

针对城市中输电线路与埋地油气金属管道临近问题,通过建立架空导/地线-杆塔-接地网-埋地管道一体化电磁场计算模型,综合考虑导线和避雷线对金属管道的感性耦合影响以及杆塔入地电流对管道的阻性耦合影响。基于此模型研究土壤电阻率、临近距离、管道参数、交叉跨越角度以及不同供流方式对金属管道电位、防腐层耐受电压的影响规律,并开展管道电位抬升的抑制方法研究,可以为输电线路发生接地短路故障时临近燃油(气)管道安全防护提供指导。

基于电子式电压互感器边界特性分析的35 kV配网输电线路单端暂态量保护方案及其整定

随着分布式电源广泛接入配电网,传统三段式电流保护方案的性能严重劣化。单端暂态量边界保护由于具备不依赖电源特性等突出优势,有望成为改善主动配电网保护配置性能的有效方案,但其需依附于线路边界强健的滤波作用。为此,该文研究发现,可利用智能变电站和智能开闭所中电子式电压互感器、金属氧化物避雷器与其余设备杂散电容共同作为线路边界,其优异的高频滤波作用能够为暂态量保护方案的设计奠定基础;其次,利用区内外故障时电压行波高频频带能量差异构造保护判据,并基于整定门槛与动作时序的合理配合形成单端暂态量阶段式保护方案;最后,基于PSCAD仿真平台验证所提方案的有效性、灵敏性与可靠性,其可与电流保护方案协同互济以强化主动配电网继电保护方案的动作性能。

金属封严环数字孪生几何模型框架的开发与应用

金属封严环广泛应用于航空发动机密封系统,其型面成形质量对飞行器高性能、高可靠服役具有重要影响。然而,薄壁、复杂的异形截面与封闭的环形结构等导致其在几何质量检测方面存在以下问题:其一,成形结果严重依赖于破坏性抽样终检,实际产品均未经过完整质量检测;其二,成形过程无几何质量检测手段,无法及时发现成形缺陷,轮廓几何数据的缺失,使工艺优化设计困难。因此,提出一种金属封严环数字孪生几何模型框架,该框架包括:物理空间、虚拟空间、交互空间与服务,可提供在机测量平台标定、截面轮廓测量、点云数据预处理、截面几何特征计算、三维数模快速构建、三维型面动态测量与偏差计算等连续成形质量在线检测技术,建立起反映金属封严环成形过程中变化的数字孪生几何模型,从而为金属封严环成形质量的检测、分析、预测以及后续工艺优化设计所需的基础数据获取等提供支撑。在此基础上,研制了在线检测模拟试验装置与数字孪生软件,介绍了金属封严环数字孪生几何模型的应用情况。

16MnCr5钢导向毂开裂原因分析

经锻造、正火、渗碳、淬火和回火的16MnCr5钢导向毂磨削后发现圆柱面有断续的周向裂纹。为查明裂纹的形成原因,对导向毂进行了化学成分检测、锻造质量检验、金相检验和硬度测定。结果表明:导向毂开裂是锻造时发生不均匀的金属流动从而形成紊乱的流线以及终锻温度太低所致。

输电线路金具表面电沉积锌-镍-金刚石复合镀层的性能

[目的]对输电线路金具进行适当的表面处理有利于延长其使用寿命,为电力系统的安全运行提供保障。[方法]采用扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)、电化学分析和摩擦磨损试验,对比了纯Zn、Zn-Ni合金和Zn-Ni-金刚石复合镀层的微观形貌、元素成分、相结构、耐蚀性和耐磨性。[结果]在研究的3种镀层中,Zn-Ni-金刚石复合镀层表面最平整致密,主要由γ-Ni_(5)Zn_(21)相和δ-Ni_(3)Zn_(22)相组成,耐蚀性和耐磨性最佳。[结论]Zn-Ni-金刚石复合电沉积在金具表面防护方面具有良好的应用前景。

使用晶圆级键合技术制备金属微结构

使用金属材料的晶圆级键合技术可以制备半封闭结构的金属矩形微同轴线。基于柔性金属衬底的晶圆级键合技术,制备了金属矩形微同轴结构。通过选择合适的对准标记和键合工艺,实现了≤10 μm的对准误差。通过多个金属矩形微同轴线的微组装,初步展示了使用单层金属矩形微同轴线构建射频开关矩阵单元的能力。

交直流输电管道绝缘运行安全关键技术

交直流输电管道具有电压等级高、电磁辐射小、敷设灵活性强等优势,在超特高压输电领域弥补了架空线路和电缆铺设的局限性,具有广泛应用前景。影响输电管道运行安全的首要因素是绝缘故障,而其中两大重要诱因是内部微粒的荷电运动和气固界面的电荷积聚。该文系统化梳理国内外相关研究,包括微粒运动与电荷积聚的时空交互、微粒与电荷积聚耦合下的放电物理机制、绝缘子性能增强设计方法、微粒抑制技术等。在此基础上总结出亟待解决的两个关键难题以及需要攻克的技术瓶颈。针对荷电微纳粉尘随机动力学特性与其诱发微弱放电的物理机制,在测量基础上须突破粉尘可视化探测瓶颈,并发展粉尘动力学行为仿真方法,以及基于飞秒瞬态光谱特征的放电检测技术。针对基于电荷调控机制的主动式微粒活性抑制理论,须开发新型涂层材料的精准制备与稳定涂覆工艺,提出主动式微粒协同抑制方法,探索智能输电管道全生命周期数字孪生技术。上述问题的有效解决,可为提升交直流输电管道绝缘安全运行水平提供理论基础和技术支撑。

重型商用车平衡轴支架铁型覆砂铸造工艺设计与优化

以某重型商用车平衡轴支架为研究对象,根据平衡轴支架的结构特点与质量要求,初步设计了平衡轴支架的铁型覆砂铸造工艺方案并进行样件试制。样件剖切结果发现在平衡轴根部厚大区域出现了较为严重的缩孔缩松缺陷。利用AnyCasting软件对平衡轴支架铸件的充型与凝固过程进行模拟仿真,仿真结果预测的铸件缩孔缩松位置与实际情况相一致。基于平衡轴支架充型与凝固过程及铸件缺陷产生原因的分析,对初始铸造工艺方案进行优化。优化后的仿真结果显示平衡轴支架铸件的缩孔缩松缺陷已基本消除。根据优化后的铸造工艺方案再次进行样件试制,样件剖切结果表明原平衡轴根部厚大区域的缩孔缩松缺陷已完全消除,平衡轴支架铸件内部质量满足要求。

高精度内花键加工方案优化

输入轴内花键精度直接影响整车的噪音、振动及舒适性。针对影响内花键累积公差和跳动公差等问题,通过试制过程中数据收集以及工艺验证,对高精度内花键加工工艺进行优化。结果表明,齿坯加工工艺、拉花键装夹方式、拉床精度水平是影响内花键精度的关键因素。

浅析钢质模锻件金属流线的取样及评定

目前锻件金属流线缺少相应的国际、国家或者行业标准,介绍了金属流线的定义和常见缺陷,论述了锻件金属流线试样制备的要求、检验面位置如何选取、试样的加工要求以及试样腐蚀的流程和注意事项等,以期能够有效地解决因取样位置差异造成的金属流线判定不准确的问题,为钢质模锻件金属流线的判定提供统一的规范,填补国内外钢质模锻件金属流线检验与判定标准的缺失。

三支柱绝缘子的设计与研究

气体绝缘金属封闭输电线路(GIL)是一种可以克服输电走廊复杂环境限制、实现城市中心大容量输电的高电压电力传输设备。GIL主要包括三支柱绝缘子、微粒捕捉器、壳体及导体等。三支柱绝缘子作为GIL的关键零部件之一,其电气性能及机械强度直接影响着GIL的运行稳定性。从GIL整体结构设计入手,详细论述了550 kV GIL三支柱绝缘子的优化设计过程,并以电磁场理论为基础对三支柱电场进行仿真解析。通过引入“电场面积”的概念,对比不同尺寸下三支柱沿面电场强度阶梯下的面积大小,得出最优结构。该设计解决了三支柱绝缘子沿面放电的问题,为GIL的开发及应用提供参考。