三辊行星斜轧机力能参数计算

论述了三辊行星斜轧机利用锥形轧辊轧制时的力能参数计单方法,包括变形区形状、接触线方程、接触弧长和接触面积,以及轧制力、轧制力矩的理论计算和数学模型。     

三辊行星轧机轧辊的不干涉条件

本文用共轭曲面法建立的轧辊不干涉条件,理论上是精确的,不干涉条件简单、实用,与一般设计方法相比轧辊直径可加大15%~20%.     

Carbothermal Solid State Reduction of Stable Metal Oxides

The paper considers carbothermal solid state reduction of manganese, titanium and aluminium oxides in argon, helium and hydrogen. The difference in reduction in helium and argon was reflected by different diffusion coefficients of gaseous reactants and products, which are much higher in helium than in argon. When carbothermal reduction took place in hydrogen, it was involved in the reduction process by reducing oxides to suboxides and forming methane. Manganese and titanium oxides were reduced to carbide Mn₇C₃ and oxycarbide Ti(O_xC_1‐x) correspondingly, while products of alumina reduction included carbide Al₄C₃ and vapours of Al and Al₂O, which were re‐oxidised to Al₄O₄C outside the reactor and deposited in the lower temperature zone. Gas atmosphere had a profound effect on the extent and rate of reduction. This effect was different in reduction of different oxides. Reduction of manganese oxides was the fastest in hydrogen, and faster in helium than in argon. Reduction of titania in argon and helium proceeded with about the same rate and was much faster in hydrogen than in the inert atmospheres. The rate and extent of alumina reduction in hydrogen and helium were higher than in argon, although no significant difference was observed in alumina reduction in hydrogen and helium. This reflects differences in reduction mechanisms, which are discussed in the paper.     

三辊定减径机轧后钢管弯曲的原因分析

无缝钢管经过三辊定减径机轧制生产工序后,有时会产生弯曲,影响产品质量和深加工.通过研究管材纵轧变形机理,从摩擦系数、变形抗力和前滑等几个方面分析了轧辊辊径、轧辊硬度、轧件温度的变化对三辊定减径机轧后钢管弯曲产生的影响.     

轧件宽度对热轧带钢轧机弹跳的影响

 轧机的弹跳方程是AGC控制系统不可缺少的模型,但轧制过程中轧机的实际弹跳与轧件的宽度有关,当轧件宽度显著偏离全辊面宽度时,轧机的弹跳也会严重偏离预压靠方法得到的结果。采用影响函数法分析了轧件宽度对轧机弹跳的影响,计算结果表明随着轧件宽度的减小,轧机弹跳宽度补偿量增加;随着轧制力的增加,轧机弹跳宽度补偿量增加。根据影响函数法计算结果,建立便于工程应用的轧机弹跳宽度补偿回归模型。     

Novel Process for Solid State Reduction of Metal Oxides and Hydroxides

Recently the reductive expansion synthesis (RES) method was introduced as a means to create nano- and sub-micron metal particles and alloys by rapid heating of physical mixtures of urea with a metal nitrate. In the present work the generality of the RES method was demonstrated by creating metal micron and sub-micron particles from oxide and hydroxide precursors, and outlining the impact of temperature, precursor ratio, and gas flow rate on the product. For example, precursor selection impacted the temperature required for complete reduction, the amount of carbon present, and the size of the metal particles. For complete NiO reduction to micron scale particles, high urea content and a high temperature [ca. 1073 K (800 °C)] were required. In contrast, Ni(OH)₂ was reduced to metal at far lower temperatures. Moreover, the Ni particles formed from NiOH were sub-micron (ca. 200 nm) in size and carbon encapsulated. Other parameter variations had a similarly significant impact. Indeed, the reciprocal relationship between inert gas flow rate and the extent of reduction supports the supposition that the primary mechanism of reduced metal particle formation is the reduction of metal oxide particles by gases produced by urea decomposition. Collectively these and other findings indicate the RES method can be manipulated to create a range of micron and sub-micron reduced metal particle architectures appropriate for different applications.     

Study of Grinding Ball Quality Properties During Manufacture in a Screw Rolling Mill

Metallurgist - The governing effect of macrostructure quality on impact resistance is established by experiment for grinding balls 50 and 60 mm in diameter prepared by screw rolling. It is shown...     

中厚板轧机的刚度与轧件宽度的关系

为得到有工程实用价值的横向刚度模型,利用正常生产中的过程操作数据分析了2 500 mm中厚板轧机在不同轧件宽度下的弹跳特性.研究结果表明,在轧制不小于半个辊面宽度范围内的板带时,刚度的减小是非线性的,而且轧机辊面越宽,刚度相对于板宽的衰减越显著.     

Study of Kinetics of Mill Scale Reduction: For PM Applications

In the deep drawing process, material of blank is transformed into the desired complicated shape by a punch. In this paper, a technique for increasing the drawability of AA1200 aluminium alloy cylindrical cups has been developed. Effects of die and punch geometry including die and punch fillet radius, on limiting drawing ratio (LDR), drawing load with respect to punch stroke and strain of the cup wall have been investigated numerically for optimal process design. A commercial finite element simulation package, ANSYS 14.0, is used in order to determine the optimum limiting drawing ratio. An experimental setup is built accordingly with a half cone angle of 18°. In the experimental and finite element analysis, AA 1200 alloy sheets are used. The effects of the original blank thickness (t = 2 mm) on the various LDR and punch load are numerically investigated. The present process successfully produces cylindrical cups with drawing ratio of 2.64.     

钼还原过程相变化研究

采用钼酸铵直接氢还原及钼酸铵先焙解然后再分段氢还原两种不同的还原方法进行了钼粉还原。通过Ｘ射线衍射方法分析了两种工艺还原过程中的反应序列及相变化规律，并讨论了不稳定相Ｍｏ４Ｏ１１对于钼粉还原过程的影响。     

Theoretical and Experimental Study of Non-Steady-State Pipe Reduction Process Using a Tesa 20-102 Mill

Metallurgist - We describe the results of an experimental study of longitudinal and transverse variations in wall thickness at the ends of pipes after rolling in a stretch-reducing mill (SRM). We...     

立式行星磨启动阶段的动力学研究

针对立式行星磨启动阶段不同转速下的载荷特点,利用多体动力学软件与有限元分析软件联合仿真,得到基于精确动力学仿真结果的行星磨磨辊系统的应力状态。根据分析结果,提出确定立式行星磨实际操作参数的依据。     

秦国东周青铜器矿料来源研究

甘肃东部及关中地区是秦文化遗址分布的密集区,这一地区发现的秦国青铜器对于研究其风格、冶铸技术、矿料来源等问题具有重要的价值。对已发表的礼县、凤翔、陇县、陈仓、秦陵等地秦国青铜器铅同位素数据进行整理分析。结果表明：春秋时期,秦国青铜器矿料特征相近,主要来自大冶铜绿山、皖南沿江及小秦岭一带。春秋早、中、晚期表现出明显的交替,这一变化与中原及汉淮地区趋于同步。战国晚期秦陵出土青铜器的矿源不同于秦国其它遗址,这一时期矿料来源地与小秦岭一带关系密切。研究结论揭示了东周时期秦国与南方地区的楚国、曾国在青铜资源流通方面的交流互动。     

低温非平衡条件下氧化铁还原顺序研究

研究了低温条件下(＜570℃)CO和H2还原氧化铁的动力学机理.结果表明:实际还原过程属于非平衡态过程,它的还原机理与还原气体的成分相关.当还原气体中CO(或H2)的含量不能满足Fe3O4 CO(H2)→3FeO CO2(H2O)反应进行的要求时,氧化铁的还原顺序为Fe2O3→Fe3O4→Fe;如果还原气体成分满足此要求,Fe2O3→Fe3O4→Fe和Fe2O3→Fe3O4→FeO→Fe两种还原顺序将同时存在.     

含碳锰团块固态还原的研究

采用反应逸出气体缸外吸收法对含碳锰团块的固态还原进行研究。结果表明，还原温度是影响还原的主要因素；在试验条件下，锰的还原并不充分，而铁的还原非常完全，铁的金属化率在１１００℃时，达９７％以上，而添加ＫＣｌ和ＢａＣｌ２盐类对还原有明显促进作用。     

Study of Transient and Steady-State Stages During Two-High and Three-High Screw Rolling of a 12Kh18N10T Steel Workpiece

Metallurgist - Test rolling is performed for austenitic steel 12Kh18N10T workpieces in two-high and three-high screw rolling mills. Differences are determined for the nature of change in hardness...