冷轧张力辊处带钢弯曲力计算公式推导

为了精确地进行张力控制,需要准确计算带钢在张力辊处的弯曲变形力消耗。本文以变形应力和应变基本理论为基础,结合弯曲变形时的特殊条件,将上述理论引入冷轧带钢在张力辊处的弯曲变形分析。详细对带钢在张力辊处的弯曲变形进行了受力和变形分析,最终推导出带钢在发生弹性弯曲、弹塑性弯曲时不同的弯曲力公式。     

圆管无模弯曲加工极限及断面扁平化实验

进行了圆管无模弯曲的基础实验研究。在无模弯曲实验研究的基础上,研究了变形区宽度等参数对圆管材极限弯曲半径的影响,分析了弯曲成形诸因素对圆管扁平化的影响。研究结果表明:在变形宽度一定的情况下,圆管扁平化随着相对弯曲半径的增加而减小;在弯曲半径一定的情况下,随着变形宽度的减小,圆管扁平化减小;圆管加工极限值随着变形宽度的增加而增加;加工极限值与相对变形宽度基本呈线性关系。     

球扁钢轧后冷却弯曲变形理论分析

对球扁钢轧后冷却过程中产生弯曲变形的原因进行了分析,弯曲变形是轧制过程中不一致的压下率和冷却过程中不均匀的温度场相互作用的结果。球头的压下率比腹板小,将导致球扁钢产生弯向腹板方向的变形;腹板的冷却速度比球头快,将导致球扁钢产生弯向球头方向的变形。要根据球扁钢弯曲变形的实际表现形式,分析引起弯曲变形的主要决定因素,采取诸如调整轧制道次压下量分配、对球头进行快速冷却等针对性措施,控制和减小球扁钢的弯曲变形。     

平整机辊系变形的有限元分析

通过对辊系变形的模拟,分析了轧制条件下对工作辊弯曲变形、支撑辊弯曲变形及接触应力的影响,借助大型有限元分析软件ANSYS的手段,对辊系进行了弹性力学结构分析,得出了在轧制过程中辊系的变形情况及载荷分布等详细直观的分析结果。     

百米U75V钢轨矫直前冷却过程弯曲变形的有限元分析

通过研究百米钢轨冷却的边界条件,采用三维瞬态非线性有限元法计算分析了百米U75V平直钢轨矫直前冷却过程中的弯曲变形变化规律。结果表明,平直钢轨在冷却过程中的弯曲变形是一个循环反复的过程,但钢轨最终是弯向轨头的;在考虑钢轨与冷床摩擦作用的情况下,平直钢轨终冷后,其变形特点是中间平直、两端弯曲,端部弯曲范围约为18 m。     

大直径硬质合金圆盘切刀烧结坯的变形控制

为了解决直径大、厚度小硬质合金圆盘切刀烧结坯椭圆变形和弯曲变形的问题，本研究探讨了压制料盒设计、石墨舟皿槽型设计、烧结涂料选择和涂刷方式等因素对烧结坯变形的影响。结果表明，缩小料盒存料空间、增加进料面积、减小出料口面积的料盒设计能有效改善制粒料下料不均现象，进而改善产品的椭圆变形，外径椭圆变形值可降至0.3mm，内径椭圆变形值可降至0.4mm；通过石墨舟皿的槽型设计，增强烧结过程中烧结坯表面与炉内气氛的接触，有利于防止烧结坯的弯曲变形；采用惰性氧化物取代含碳有机物涂料对石墨烧结舟皿进行防黏处理，可使烧结坯弯曲变形值降至0.1 mm；对石墨舟皿进行双面涂刷对烧结坯弯曲变形控制的效果优于单面涂刷。     

板带轧制头部弯曲机理的研究

对板带轧制过程中产生的头部弯曲从理论上进行了研究。结果表明：简单对称轧制过程中轧件不会产生头部弯曲;对于异步轧制而言,轧制过程是轧件压缩、剪切和弯曲变形的复合变形过程,由于金属的流变状态和力学状态的不对称,全后滑产生的不均匀应力导致轧件头部易产生弯曲。     

热轧钢板头部弯曲行为的人工神经网络预报模型

根据单机架2500四辊可逆式轧机钢板轧制的实测数据,采用人工神经网络方法建立了钢板头部弯曲行为预报模型。结果表明,轧制过程钢板头部弯曲的人工神经网络计算值与实测值符合;当轧件上下表面温度相差较大时,上下表面温差、变形区形状特征和变形程度是影响轧件头部弯曲的主要因素。对于厚的成品板,减小道次压下量可减小弯曲;对薄成品板,增加道次压下量可减小弯曲。     

高压电机转子主轴断裂的修复实践

针对高压电机主轴断裂修复过程中容易产生焊接弯曲变形的问题进行了分析,提出了具体的修复方案。通过采用销孔定位更换轴头保护焊接的方法,很好地解决了主轴断裂焊接弯曲变形问题。     

双钟机械炉顶高炉料钟拉杆弯曲变形事故分析与处理

针对安钢5号300m^3高炉大料钟拉杆弯曲变形，导致大钟关闭不严、炉顶压力波动大，严重影响高炉炉况顺行的实际情况，分析了大料钟拉杆发生弯曲变形的原因，探讨了快速更换拉杆的可行性方案。     

Within-child associations between family income and externalizing and internalizing problems.

Within-child associations between family income and child externalizing and internalizing problems were examined using longitudinal data from the NICHD Study of Early Child Care and Youth Development (2004a, 2004b; N = 1,132). Variations in income effects were estimated as a function of whether families were poor, whether mothers were partnered, and the number of hours mothers and their partners were employed. On average, children had fewer externalizing problems during times when their families' incomes were relatively high than during times when their families' incomes were relatively low; the estimated benefits of increased income were greatest for children who were chronically poor. For both externalizing and internalizing problems, income was most strongly associated with problems when chronically poor children's mothers were partnered and employed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

FeCuNbSiB粘结磁体的制备及磁性能研究

通过2种途径将熔体快淬法制得的FeCuNbSiB非晶薄带制成环状粘结磁体。一是将非晶薄带进行晶化处理,再将晶化后的薄带粉碎成不同粒度的粉末,然后与粘结剂相混合制成粘结磁体。二是将非晶薄带直接粉碎成不同粒度的粉末,再将此粉末进行晶化处理,将晶化后的磁粉与粘结剂相混合制成粘结磁体。分析了磁粉粒度和模压压力对粘结磁体性能的影响。并对两种粘结磁体的性能进行比较。结果表明,第一种方法制备的粘结磁体的性能优于第二种。     

铸坯内部缺陷对钢板分层形成的影响

探测和解剖分析了断面有中心裂纹缺陷的铸坯;用扫描电镜等分析了依照探伤图谱所选轧后钢板分层缺陷明显部位的金相组织、缺陷形态和微区成分;指出了其沿轧向分布的铁素体带及其内部的条状或片状硫化物是中厚板分层的主要成因;给出了铸坯内部轧制时焊合及修复的边界条件。     

Reliability of Settlement Prediction—Case History

A geotextile-reinforced embankment was built over soft ground. Staged construction and vertical prefabricated drains were used to obtain strength gain via consolidation of the foundation material. Settlement and pore pressure were measured as a part of construction control. Settlement, differential settlement, and rate of consolidation were predicted by simple models. Uncertainties in the predictions were evaluated to assess the reliability of the predictions. The estimated errors were compared with the measured values, and major contributors to prediction errors were identified.     

钢管标准化工作的思考

综观钢管专业领域内的国内、国际现状和发展趋势,重点介绍了钢管专业标准化工作基本情况、作用和主要成绩;对目前标准化工作存在的主要问题及原因进行分析;指出在国内、国际环境下对标准化工作提出的要求;深入探讨钢管专业标准化工作的重点任务、领域及重点项目。     

D200—Ⅱ型离心风机振动故障诊断和处理

简介了D200—II型离心风机振动故障情况,分析了故障原因,阐述了采取的处理措施,说明了处理后的运行效果,总结了经验教训。     

Evaluation of Flexural Behavior and Serviceability Performance of Concrete Beams Reinforced with FRP Bars

Flexural behavior and serviceability performance of 24 full-scale concrete beams reinforced with carbon-, glass-, and aramid-fiber-reinforced-polymer (FRP) bars are investigated. The beams were 3,300?mm long with a rectangular cross section of 200?mm in width and 300?mm in depth. Sixteen beams were reinforced with carbon-FRP bars, four beams were reinforced with glass-FRP bars, two beams were reinforced with aramid-FRP bars, and two were reinforced with steel, serving as control specimens. Two types of FRP bars with different surface textures were considered: sand-coated bars and ribbed-deformed bars. The beams were tested to failure in four-point bending over a clear span of 2,750?mm. The test results are reported in terms of deflection, crack-width, strains in concrete and reinforcement, flexural capacity, and mode of failure. The experimental results were compared to the available design codes.     

抑制剂对超细WC-Co硬质合金性能的影响

采用高能球磨、真空烧结工艺制备超细WC-Co硬质合金。研究了抑制剂的预磨时间对WC-10Co硬质合金粒度及烧结试样性能的影响。对比了相同抑制剂配比对Co含量不同的硬质合金性能的影响以及稀土对硬质合金性能的影响。结果表明:通过对晶粒长大抑制剂的预磨,其粒度明显细化。加入预磨时间为120 h的抑制剂,WC-10Co硬质合金的平均粒度为0.3μm,硬度达到92.1 HRA。相同抑制剂配比的硬质合金,硬度和致密度随Co含量的降低而增大。稀土氧化物Y2O3的加入,有利于改善硬质合金的性能。     

热处理对纳米氧化锆粉末性能的影响

采用共沉淀法制备纳米ZrO2粉末,对其进行不同温度下的热处理,并对经过热处理的粉末进行物理性能及形貌的测试分析。对经过热处理的粉末进行等离子球化处理,并对其形貌进行观测。采用等离子喷涂方法制备ZrO2涂层,对涂层形貌进行观测。结果表明在适当温度对ZrO2进行热处理可提高粉末松装密度、流动速率及表面光洁度,提高粉末和涂层的综合性能。     

电流变流体和磁流变流体在工程上的应用

阐述了ER和MR流体的组成及发展过程，并对它们的物理和化学性能进行了对比分析，总结了现有ER和MR流体的理论计算模型、应用领域和应用状况，提出了ER和MR流体阻尼装置的分类方法及使用时应注意的几个问题，最后对ER和MR流体现存的问题和发展方向作了分析和展望。