对圆形线材轧扁过程中轧制力公式的研究

扁钢丝应用越来越广泛,国内外对其轧制力公式鲜有研究。本文从轧件变形率、轧件与轧辊的接触面积两方面对斯通公式进行优化,使其适用于圆形截面的线材扁平化轧制。将斯通公式中用高度压下表示的变形率ε改为ε'轧件横截面积表示的变形率,并拟合出ε'与ε的非线性方程;对轧件与轧辊的接触形状做了椭圆的假设并推导出了接触面积影响系数S。结合对斯通公式两方面的改进得出优化后的计算公式。对轧扁过程进行了数值模拟和实验测定,提取轧制力进行结果比较分析,得出改进后的计算公式能够很大程度的提高轧制力计算精度,这对实际工程应用有极大意义。     

冷轧轧制能力计算的新方法

目前,冷轧轧制能力的计算方法。一般采用M.D.斯通公式[1]、[2].尽管手工计算冷轧轧制力很麻烦,总还是一种设计计算求解方法。由于计算技术的迅速发展,借助于微型计算机,使得冷轧轧制能力的计算显得非常简单可行。本文介绍一种冷轧轧制能力计算     

CSP生产线轧制力模型研究

根据Sims公式和Bland-Ford-Hill公式计算了武钢CSP生产线7机架的轧制力,并与实际轧制力对比分析,偏差较大。这是由于CSP线采用了工艺润滑,摩擦状态复杂,现有模型不再适用,为此,针对CSP线建立了新的轧制力数学模型。结果表明,新模型计算值与实测值基本吻合,计算精度较好,预报准确率大幅提高。     

冷轧金属变形阻力曲线的回归及轧制力的电算方法

对于冷轧带钢一般采用斯通公式计算轧制力,为方便计算,提高精度,本文采用牛顿迭代法计算轧辊弹性压扁后的接触弧长,并编制了电算程序。文中还将常用的十一个钢种及四种有色金属的变形阻力曲线运用回归方法,得出的回归方程也编于程序之中。电算结果与实测值作了比较,其误差在工程允许的范围内。     

一种计算椭圆圆孔型影响系数n_k的新方法

轧制力是金属轧制成形过程中的重要技术参数之一。利用有限元软件ANSYS/LS-DYNA建立了椭圆圆孔型轧制过程中的三维刚塑性有限元模型,得到了从咬入到稳定轧制每时刻的压下、宽展及轧制力值。并结合孔型轧制时的一般计算公式,采用MATLAB程序实现数值的拟合,推导出一个简单的计算椭圆圆孔型系统的增压系数的公式,以准确计算孔型轧制过程中的轧制力。并对有限元推导出轧制力公式的计算值和实际轧制得到的轧制力值进行比较,二者的相对误差在4%以内。     

双周经验公式应用于冷轧钢带的轧制力计算

应用双周经验公式计算了冷轧钢带的轧制力,6个实测例子的计算值平均相对误差为16．78％。应用双周经验公式可以简化采利科夫公式运算过程,有推广价值。     

带材轧制力计算新方法

采用一种新的计算方法对带材轧制时的轧制力及前滑进行计算，并与文献中的实测数据及刚－塑性有限元法的计算结果进行了比较，结果表明新计算方法简便有效。     

铝箔轧制力的计算与应用

轧制力计算是轧机设计的基本参数之一,也是编制轧制工艺不可或缺的重要参数.在现有的技术文献中,计算轧制力的公式很多.但是要找到适合现场,快速、准确、简便的计算铝箔轧制的轧制力的计算公式却十分困难.根据现场的实践经验,并参照多家世界知名的轧机制造厂商的轧制力计算结果,总结出了便于现场使用的铝箔和板带轧制力的计算公式.     

基于影响函数法的冷轧带钢轧制力计算

根据经典轧制力模型 ,在考虑轧制力模型与轧辊压扁模型耦合的前提下 ,开发了基于影响函数法的冷轧带钢轧制力计算程序 ,并用实际生产中的采样数据模拟计算了HC轧机各道次的轧制压力分布和总轧制力 ,将所得计算结果与现场实测数据进行比较。结果表明 :所得轧制力计算结果与实测值相近 ,轧制压力分布与实际相符 ,为HC轧机板形控制提供了一种计算轧制力的有效方法。     

方坯料在椭圆孔型中轧制时力能参数的计算

本文按Ritz法求解最小能量方程,得到了方钢在椭圆孔型中轧制时金属的三维位移和应变。按三维变形,应用能量平衡原理推导出轧制力和轧制力矩的计算公式,并对理论公式进行了实验验证,公式计算值与实测值相近。     

盐酸埃他卡林对自发性高血压大鼠肾组织KATP通道基因表达的影响

目的: 从分子生物学水平探讨盐酸埃他卡林(iptakalim hydrohloride, Ipt) 对自发 性高血压大 鼠(spontaneously hypertensive rats, SHR) 肾组织 K_ATP 亚型表达的影响。方法: SHR 于第 12 周龄进入实验, 实验设 Ipt 1、3 和 9 mg°kg^-1°d^-13 个剂量组, 盐酸苯那普利(benazepril) 3 mg°kg^-1°d^-1治疗组及 SHR 空白对照组, 另设同周龄同种属正常血压大鼠(wistarKyoto rat,WKY) 为正常对照组, 灌胃给药每天 1 次,连续 12周, 观察盐酸埃他卡林对血压和肾组织 K ATP亚型表达的影响。结果: SHR肾组织SUR2、Kir6.1、Kir1.1 mRNA 表达较WKY 大鼠明显升高, 盐酸埃他卡林 1、3、9 mg°kg^-1°d^-13 个剂量组治疗后均可明显降低血压同时下调肾脏高表达的 Kir6.1、Kir1.1mRNA 水平, 而对 SUR2 表达无明显影响。结论: 盐酸埃他卡林对 SHR 降压治疗对肾脏的保护作用可能与其影响Kir6.1、Kir1.1 基因表达有关。     

A two phase elastic–plastic self-consistent model for the accumulation of microstrains in Waspaloy

A two phase self-consistent scheme for the accumulation of elastic lattice strains in the nickel-base superalloy Waspaloy is presented. The microstructure is idealised as a set of randomly orientated anisotropic grains which are assumed to be spherical and embedded within a homogenous effective medium which is assigned the properties of the bulk. Each grain is modelled as a medium with the properties of identically aligned cubic γ-Ni with a spherical inclusion of γ′-Ni₃Al. The γ′ is treated as an elastic anisotropic solid, and the γ is modelled as an elastic–plastic single crystal according to the Taylor–Bishop–Hill plasticity theory. The diffraction elastic constants and microstrains accumulated are compared with those found experimentally using neutron diffraction, as previously reported by Stone et al. The predictions are found to be adequate, and in particular the shift of load, as reflected in the microstrain, from the matrix to the precipitate between 3 and 10% plastic strain is reproduced. The implications of these results for the development and use of Reitveld-derived schemes for the measurement of bulk residual stress at spallation sources are discussed.     

工程设计演示文档动态性表述的探讨

在工程投标、方案论证、学术交流中 ,可利用多媒体演示软件制作各类文档。为了充分表达制作人员的思想 ,达到预期目的 ,可采用丰富多彩的动态性表现手法 ,使演示产生很好的效果 ,令听众和观众欣然接受。为此 ,对工程设计演示文档的动态性表述进行了探讨 ,以便能更充分地发挥多媒体演示软件的作用     

The effect of yield criteria on the forming limit curve prediction and the deep drawing process simulation

The increasing application of numerical simulation in the field of metal forming has helped engineers to solve problems one after another to manufacture a qualified formed product in a reduced time. Accurate simulation results are vital for die and product designs. Many factors can influence the final simulation result, the most important of which is a suitable yield criterion. The proposed Forming Limit Curve (FLC), which is used to evaluate the necking risk, differs a lot while different yield criteria used. In this study, the theoretical FLC is calculated using Swift model, which considers three-yield criteria Hill 48, Hill 90 and Hill 93. Also, the simulation processes with two yield criteria, Hill 48 and Hill 90, are carried out with two types of material, SPCC (JIS G3141) and Al6xxx. The strain evolutions of elements located in two trajectories of two materials are investigated and compared. The simulation results are compared with the experimental ones to evaluate the effectiveness of the yield criterion.     

改进的综合等负荷函数法在可逆轧机压下分配中的应用

比较若干种轧制规程设计方法 ,认为改进的综合等负荷函数法适合实验轧机的压下规程设定。参数的改进很好地解决了程序的收敛性 ,并比较各种传统模型找出了最优模型。同时 ,在不同情况下使用不同模型有较好效果。Stone模型和连家创模型的改进拓宽了它们的应用。     

Effect of backfilled stone/brine media on the initial electrochemical performance of aluminum sacrificial anode

Aluminum alloy sacrificial anodes applied to protect the subsea immersed tunnels' steel shells are buried in an unfamiliar inhomogeneous backfilled stone/brine media. To verify its influence, the effect of the backfilled stone (10–12, 6–10, and 3–6 mm)/brine (40 Ω cm) media, denoted as Stone 1, Stone 2, and Stone 3, on the initial electrochemical performance of an Al─Zn─In─Si─Sn─Ti anode is investigated by electrochemical and surface analysis techniques. With decreasing the stone size, the Stones 1–3 media's resistivity increases to 100, 125, and 150 Ω cm, respectively. The backfilled stone/brine media inhibits the anode′s free corrosion and pitting process and accelerates its activation in the initial period. The anode′s capacity and current efficiency decrease slightly; however, the anode′s output current and its transmission are depressed more heavily by decreasing the backfilled stone size. Also, the backfilled stone shields parts of the cathode surfaces, decreases dissolved oxygen concentration, and blocks the diffusion of the anode's dissolution product in the media, resulting in the change of the anode's protective effect.     

各向异性屈服准则对不锈钢板冷弯成型回弹模拟的影响

基于不锈钢板冷弯成型和回弹过程的数值模拟,研究了各向异性屈服准则Hill和YLD89对不锈钢板冷弯成型模拟的影响。模拟结果与试验值的比较表明,屈服准则YLD89较适用于不锈钢板的冷弯成型模拟。     

乙醇对体外培养的2.2.15 细胞中HBV 复制和表达的影响

目的:探讨乙醇对乙型肝炎病毒复制和表达的影响。方法:采用人HBV DNA 转染的细胞株2.2.15 细胞作为研究对象, 以不同浓度的乙醇进行干预, 同时设立阴性对照、3TC 阳性对照, 观察乙醇对HBV 表达和复制影响, 并检测细胞内抗病毒基因MxA 的表达情况。结果:乙醇能够加强培养上清液中乙肝表面抗原、e 抗原以及细胞内核心抗原的表达, 而3TC 组三种抗原均无明显影响;Southern 印迹显示, 乙醇于200 mmol°L^-1时明显加强HBV DNA 的复制, 3TC 于2 μmol°L^-1 浓度时则明显抑制HBVDNA 的复制;乙醇于40 mmol°L^-1 时, MxAmRNA 表达显著加强, 3TC 于2 μmol°L^-1 时MxAmRNA 亦明显表达增加。结论:乙醇能刺激乙肝表面抗原、e 抗原以及核心抗原的表达, 同时细胞内抗病毒基因MxA表达亦增加, 可能与乙醇非特异性增强细胞内酶的活性, 加强细胞内合成代谢有关;乙醇可以促进HBV 复制, 但机制有待研究。     

Effect of final heat treatment on creep behaviors of Zr-Nb-Cu alloy cladding tubes

Creep properties of annealed and stress-relieved Zr-1.1Nb-0.05Cu cladding tubes were studied and compared. The creep rates of Zr-1.1Nb-0.05Cu cladding tubes stress-relieved at 560°C were found to be appreciably higher than those of Zr-1.1Nb-0.05Cu annealed at 700 °C. The stress exponents for steady state creep were observed to be 5.0~7.0 for both stress-relieved and annealed Zr-1Nb-0.05Cu, supporting that the dislocation-climb-controlled creep operates at the intermediate temperatures (450~500 °C). The creep activation energy increased appreciably in the annealed Zr-1.1Nb-0.05Cu alloy compared to those of stress-relieved alloy. The increase of activation energy in the annealed Zr-1.1Nb-0.05Cu alloy is attributed to the decreasing contribution of faster diffusion path such as grain boundaries and dislocations. The creep rate of Zr-1.1Nb-0.05Cu decreased at intermediate temperatures with the increase of grain size with heat treatment, supporting the creep performance can be improved by the modification of microstructure through annealing.     

圆筒件拉深成形临界防皱变压边力加载曲线研究

针对板料拉深成形过程中如何最优控制压边力的难题,文章首先从理论上分析了圆筒件拉深成形过程中法兰上任一点处的承载能力,建立其应力应变平衡关系,从而得到法兰上任一点处的瞬时径向拉应力和周向压应力公式;其次结合法兰起皱有关能量守恒定理和Hill厚向异性理论,推导出了包含摩擦系数和板料厚向异性系数在内的法兰起皱临界最小压边力公式,并分析了各种拉深成形工艺参数对此法兰起皱临界最小压边力大小的影响规律;最后应用数值模拟软件eta/DYNAFORM验证此临界变压边力加载曲线的可行性,并修正其表达形式。最终板厚变化量的均方差计算结果表明,理论推导的起皱临界最小压边力修正加载曲线,不仅比常见的最小压边力恒定加载模式更节省能量,而且其厚度分布也更加合理、均匀。