TWO KINDS OF VARIANT IN SHAPE MEMORY MATERIAL

In shape memory materials,that have been trained to have a two way shape memory effect(TWSM),themartensitic variants are classified into two groups,i.e.,preferentially oriented variants and self-accommodatingvariants.Applied stress may promote or constrain the transition of preferentially oriented variants and so changetransformation temperatures but has no essential effect on self-accommodating variants.According to the pointof view mentioned above,some experimental phenomena during thermocycling of a TWSM device may be ex-plained,such as the absence of synchronization between the plot of resistance change.temperature and the plotof memory strain vs.temperature.     

型内感应加热铝-钢双金属复合界面的研究

双金属复合铸件外圈采用铸造铝合金，内圈选取碳素结构钢，采用型内感应加热工艺进行复合。造型时内层钢套预先放置在砂型中，复合时将包含有钢套的砂型整体放人到感应圈内采用中频感应原理对钢套进行预热，达到预定温度后浇注并继续进行加热，复合层将基体钢套包覆后停止加热。所得到的双金属复合铸件结合界面为完全冶金结合，复合层组织为连续分布FeAl3与Fe2Al5中间化合物，界面结合强度为76．4MPa。     

Vogel—Fulcher定律与玻璃转变温度的关系

通过在不同加热速度，不同坩埚材料和不同样品质量条件下测定Ｉｎ，Ｚｎ，Ｓｎ，Ｐｂ等元素的熔点，校正了加热速度对差示扫描量热仪显示温度的影响。根据对仪器温度校正的结果，研究了Ｎｉ３３Ｚｒ６７，Ｚｒ６５Ａｌ７．５Ｎｉ１０Ｃｕ１５Ｃｏ２．５，Ｐｔ６９．０Ｎｉ９．６Ｐ２１．４，聚醚砜和聚苯乙烯等材料的玻璃转变的动力学特征。     

轧钢加热炉节能技术现状和展望（二）

在介绍我国轧钢加热炉的现状及节能工作发展的基础上，着重介绍了用于加热炉的一批成熟、行之有效的节能技术，如炉型改造、燃烧技术、烟气余热回收、炉料热送热装等；并对今后如何抓好轧钢加热炉的节能工作提出建议。     

金属材料直接接触加热熔化过程的研究

采用准稳态法对电加热管直接接触加热金属材料的熔化过程进行了研究，获得了金属材料在熔化过程的温度分布、界面移动规律以及电加热管表面温度的变化与表面热负荷的关系，并通过试验验证了电加热管在金属熔化过程中表面温度的变化规律。理论计算结果表明，当电热管加热功率密度较大时，其表面温度和金属材料温度均不会大幅度升高；理论和试验结果的比较表明，电热管表面温度的理论计算结果和试验结果较为一致。     

A new thermomechanical model of cutting applied to turning operations. Part I. Theory

In this paper, an analytical approach is used to model the thermomechanical process of chip formation in a turning operation. In order to study the effects of the cutting edge geometry, it is important to analyse its global and local effects such as the chip flow direction, the cutting forces and the temperature distribution at the rake face. To take into account the real cutting edge geometry, the engaged part in cutting of the rounded nose is decomposed into a set of cutting edge elements. Thus each elementary chip produced by a straight cutting edge element, is obtained from an oblique cutting process. The fact that the local chip flow is imposed by the global chip movement is accounted for by considering appropriate interactions between adjacent chip elements. Consequently, a modified version of the oblique cutting model of Moufki et al. [Int. J. Mech. Sci. 42 (2000) 1205; Int. J. Mach. Tools Manufact. 44 (9) (2004) 971] is developed and applied to each cutting edge element in order to obtain the cutting forces and the temperature distributions along the rake face. The material characteristics such as strain rate sensitivity, strain hardening and thermal softening, the thermomechanical coupling and the inertia effects are taken into account in the modelling. The model can be used to predict the cutting forces, the global chip flow direction, the surface contact between chip and tool and the temperature distribution at the rake face which affects strongly the tool wear. Part II of this work consists in a parametric study where the effects of cutting conditions, cutting edge geometry, and friction at the tool–chip interface are investigated. The tendencies predicted by the model are also compared qualitatively with the experimental trends founded in the literature.     

国产中频加热电源装置在管端加厚机上的应用

宝山钢铁股份有限公司钢管分公司管端加厚机的管端局部加热装置原采用德国提供的中频感应加热电源装置,因长期运行致使其性能老化,不能满足生产要求,现已采用国产装置替代。介绍了该国产装置的组成、特点及控制回路原理。实践证明,国产装置同样具有稳定可靠、控制精确、保护功能齐全等特点。使用该国产装置已取得较好的经济效果。     

A new thermomechanical model of cutting applied to turning operations. Part II. Parametric study

In Part I of this work, Molinari and Moufki [Int. J. Mach. Tools Manufact., this issue], an analytical model of three-dimensional cutting is developed for turning processes. To analyse the influences of cutting edge geometry on the chip formation process, global effects such as the chip flow direction and the cutting forces, and local effects such as the temperature distribution and the surface contact at the rake face have been investigated. In order to accede to local parameters, the engaged part in cutting of the rounded nose is decomposed into a set of cutting edge elements. Thus each elementary chip, produced by a straight cutting edge element, is obtained from an oblique cutting process defined by the corresponding undeformed chip section and the local cutting angles. The present approach takes into account the fact that for each cutting edge element the local chip flow is imposed by the global chip movement. The material characteristics such as strain rate sensitivity, strain hardening and thermal softening, the thermomechanical coupling and the inertia effects are considered in the modelling. A detailed parametric study is provided in this paper in order to analyse the effects of cutting speed, depth of cut, feed, nose radius and cutting angles on cutting forces, global chip flow direction and temperature distribution at the rake face. The influence of friction at the tool–chip interface is also discussed.     

Smith模糊PID匀速升温控制策略研究

针对电加热炉匀速升温过程模型建立困难、调节过程滞后等问题,提出了一种基于炉体散热补偿的Smith模糊PID控制算法。通过炉体散热补偿建立针对被控量升温速率的一阶线性纯滞后模型;采用Smith预估器消除纯滞后特性带来的影响,提高系统的稳定性,加快调节过程;引入模糊PID控制,克服Smith预估补偿环节鲁棒性差的弱点,实现参数的自适应调整,并提高了稳态精度,实现了高精度的匀速升温控制。试验结果表明,该控制策略的控制偏差低于5%,明显优于常规PID控制。     

油井电磁清蜡器中电磁-热耦合场的数值模拟

为了减少感应加热对电磁清蜡器腔管的热蚀,提高电磁清蜡器的使用寿命,在分析油井电磁清蜡器感应加热过程的基础上,利用ANSYS的APLD语言建立了电磁清蜡器的电磁热耦合场有限元模型.重点对油井电磁清蜡器处理腔管中的电磁—热耦合场进行了仿真分析,得出了腔管内外壁的温度分布规律.仿真结果表明:电磁感应加热5s,钢管表面温度升高至175.128℃;加热10s钢管表面温度达到了343.286℃,避免了常规电阻式加热钢管明显的温升滞后现象,体现了电磁感应加热的升温速度快的特点,20s后钢管内的温度分布比较均匀,钢管总体温度在490～ 569℃的范围内,钢管内壁与钢管表面温差在77.323℃以下.