Zonal method solution of radiative heat transfer in a one-dimensional long roller-hearth furnace in CSP

A radiative heat transfer mathematical model for a one-dimensional long furnace was set up in a through-type roller-hearth furnace （TTRHF） in compact strip production （CSP）. To accurately predict the heat exchange in the furnace, modeling of the complex gas energy-balance equation in volume zones was considered, and the heat transfer model of heating slabs and wall lines was coupled with the radiative heat transfer model to identify the surface zonal temperature. With numerical simulation, the temperature fields of gas, slabs, and wall lines in the furnace under one typical working condition were carefully accounted and analyzed. The fundamental theory for analyzing the thermal process in TI＇RI-IF was provided.

THE 3-D BOUNDARY ELEMENT METHOD OF ROLLER BEARING BY PLATE ELEMENT ANALOGUE

The mill roller bearing is made up of an internal ring, middlerolls and an external ring, the analysis of which is a multi-bodiescontact problem. In this paper, based on the three-dimensionalelastic contact BEM without friction, and using the structuralcharacteristics of roller bearings, middle rolls are de- scribed byelastic plate units of different shapes, which is placed on theinternal ring.

A MIXED METHOD OF DETERMINING THETHERMAL STRESS FOR COLD ROLLER

A mixed method which combines the recent developed finite analytical method and the boundary fitting coordinate transformation method was used first to calculate the temperature field and thermal stress field of the cold roller in this paper. The following results are obtained by the calculation: thermal stresses σr=0, σθ=σz are maximum tension stress on the inner surface of the cold roller and σr=0, |σθ|=|σz| are maximum compression stress on the outer surface of the cold roller in the steady and unsteady case. Effectiveness and validity of the mixed method are checked with steady coil roller problems having theoretical solutions. The results show that good agreement is achived between the calculated value and theoretical solution,and the mixed method used in the paper is very workable. The mixed method is also useful in solving the steady and unsteady thermal stress field proplems of the hot -rolled for the reversing rolling mill and the continous rolling mill.

Effect of roller shapes on strip buckling in a continuous annealing furnace

The effect of roller shapes on strip buckling in a continuous annealing furnace was focused on. The tensile stress distribution, the transverse compressive stress, and the critical buckling stress of the strip were studied by the finite element method （FEM） when the flat roller, crown roller, single taper roller, and double taper roller were used, respectively. Simulation results show that strip buckling is most likely to occur with the crown roller, then the double taper roller, and finally the single taper roller. Also, strip buckling can not occur when the flat roller is used. Considering strip snaking, the single taper roller and double taper roller are suggested in the continuous annealing fur-nace. The double taper roller with a better strip snaking-prevention ability should be applied in the sections with high strip temperature, and the single taper roller with a better buckling-prevention ability should be used in the sections with low strip temperature.

Structure and electrochemical properties of hypo-stoichiometric hydro-gen storage alloys prepared by twin-roller rapid quenching process

The stoichiometric alloy MlB5.0 and the hypo-stoichiometric alloy MlB4.85 were prepared by twin-roller rapid quenching process, and their structure and electrochemical properties were studied. The results of XRD show that both of the alloys have a typical single-phase hexagonal CaCus-type structure. The cell volume of the hylpo-stoichiometric alloy M1B4.85 is slightly larger than that of the stoichiometric alloy M1B5.0, although its lattice constant cla is smaller. Under 2 C discharging rate, i.e. 640 mA/g, the M1B4.85 has a discharge capacity of 320 mAh/g, which is higher than that of the M1Bs.o, 312 mAh/g. Nevertheless, the capacities of the M1B4.85 and the M1Bs.o decline 24.7% and 20.2% after 400 cycles, respectively. The relationship of electrochemical performances of the alloys with their structures is discussed.

Stiffness of high-speed cylindrical roller bearing subjected to radial force and bending moment

Presents a practical way of calculation for stiffness of cylindrical roller bearing based on traditional quasistatic analytical methods subject to radial force and bending moment,which take into consideration the effect of such factors as thickness of oil elastohydrodynamic film,pressure,shear force,friction force of cage,centrifugal force and slides,taken into consideration and presents the results of stiffness calculation with a typical example with an aeroengine cylindrical roller bearing were given in the paper.And,discusses the effect of major parameters’influence on stiffness.

基于层次分析法的TBM滚刀评价方式

[目的]为了减少TBM(硬岩隧道掘进机)在高磨蚀性岩层中掘进时的换刀次数,以及选出最适用于高磨蚀性岩层的滚刀,提出一种基于层次分析法的滚刀评价方法。[方法]建立了滚刀磨损失效危害评价模型;选取7个磨损失效类型因素,基于层次分析法建立了滚刀磨损失效危害评价模型和比较判断矩阵,计算出各失效类型危害的占比;以广佛东环城际铁路大源站至太和站区间线路为例,对4个常用品牌的滚刀进行定量分析;建立风险评价分值表,分析4个品牌的滚刀在使用过程中的失效影响评价值。[结果及结论]高磨蚀岩层中的滚刀非正常磨损占比为23.29%,正常磨损占比为76.71%。c品牌和d品牌滚刀的失效影响评价值分别为7.141和4.816,远小于a品牌滚刀的失效影响评价值7.587和b品牌滚刀的失效影响评价值9.058。d品牌滚刀的相对磨损速率大于c品牌滚刀,因此c品牌滚刀最适用于高磨蚀性岩层。a品牌滚刀适用于硬度极大的岩层,b品牌滚刀不推荐使用,d品牌滚刀适用于硬度较小的岩层。

Torsional Vibration of Roller Oscillating Tooth Gear Drive

Torsional vibration of roller oscillating tooth gear drive (ROTGD) is studied in this paper. On the basis of conservation law for kinetic energy and potential energy, the mathematical expressions are developed which describe transformation of moment of inertia of inertial components into input shaft. Also, the formula is derived which expresses transformation of contact stiffness of elastic components into input shaft torsional stiffness. Besides, torsional vibration model of ROTGD is presented by using the transfer matrix method, and natural frequencies and vibration mode shapes are determined. Eventually, an example is given.

Model Building of Backup Roller Diameter Effect Rate in 4-High Mill

Software for calculating the strip profile in 4-high hot rolling mill was developed using influence coefficient method. Regularity of backup roller diameter effect rate was studied systematically using the software. The results show that backup roller diameter effect rates decrease versus the increase of strip width, increase significantly versus the increase of backup roller diameter and obscurely increase versus the increase of reduction. The difference between backup roller diameter effect rate and it is reference value increases versus strip width increasing. When backup rollers diameter is set to be 1.64 m and strip width is 1.85 m, the error of strip profile calculated using the model of backup roller diameter effect rate reference value will be 3.55μm. Based on the results, reference values of roller diameter effect rate and six power polynomial fitting coefficients of modification coefficients were determined considering coherent parameters. The high precision model of backup roller diameter effect rate was established. When the model is used to predict strip profile, the accuracy is less than 5.0 μm.

Profiled Cylindrical Roller Design in Consideration of Grinding Undercut Effect

In this paper, the effect of the grinding undercut of the raceways on the longitudinal pressure distribution of the profiled rollers, which are the most popular axial profile employed by the bearing manufacturers, was discussed. Based on the profiled roller geometrical equations and numerical calculation of three dimensional elastic contact problems of finite length, a new numerical method for calculating the crown drop evaluation considering the effect of grinding undercut was used. The analyses of two structure case, that roller length is greater or less than raceway width, were carried out and compared with each other. The Results show that the width of grinding undercut must be considered in determining the crown drop of rollers.

带式输送机不停机托辊更换车结构设计及特性分析

为提高煤矿带式输送机在更换损坏托辊时的维护效率,减小人工更换产生的安全风险,文中设计了一种可在带式输送机不停机状态下进行托辊更换的更换车。针对不停机更换托辊的工作要求,确定更换车的更换方案,并建立三维模型。采用D-H参数法建立更换车机械手的连杆坐标系,通过MATLAB软件机器人工具箱建立机械手模型,并用蒙特卡洛法确定机械手的工作空间,结果表明,其运动范围满足槽型托辊组3个托辊的更换。采用ADAMS软件对机械手拆卸和安装托辊过程进行仿真,得到损坏托辊和备用托辊的位移曲线,结合夹取结构的运动曲线和运行轨迹,结果表明,机械手的工作过程平稳流畅。采用ANSYS软件对更换车工作中关键受力部件支撑臂和支撑托辊架进行有限元分析,结果表明:两部件强度满足工作要求,保证更换车工作的可靠性。

基于有限元的热力耦合场匣钵运动分析与优化

为解决装有锂离子电池正极材料的匣钵在辊道窑烧结过程中易出现异常横向运动使匣钵破损的问题,本研究通过分析匣钵异常运动特性的影响因素对其进行优化。首先,利用Solidworks软件建立辊道-匣钵传动系统简化模型,对匣钵进行受力分析,推导出匣钵发生异常横向运动的原因是辊棒的弹性变形;其次,通过Abaqus软件进行有限元仿真,对比分析热力耦合场和重力场下匣钵的位移曲线以及辊棒的受力情况。结果表明,与重力场相比,热力耦合场的辊棒弹性变形量更大,且热力耦合场匣钵横向位移在0~1 s内相对重力场增大,而在1~5 s内相对重力场减小,说明在温度和重力共同作用下所引起的辊棒弹性变形是导致匣钵异常横向运动的主要原因。在此基础上,设计了一种匣钵传动机构,包括辊棒支撑机构、匣钵夹紧装置及匣钵挡齐装置,并通过对比生产验证了改进机构的可行性。本研究对在辊道窑烧结过程中匣钵异常横向运动的影响因素进行分析并提供了一种改进机构,有助于推进锂离子电池正极材料生产设备的发展。

行星滚柱丝杠螺纹副-齿轮副同步啮合动态滑动特性

为揭示行星滚柱丝杠螺纹副-齿轮副同步啮合动态滑动特性,推导了行星滚柱丝杠滑动角计算方法,建立了行星滚柱丝杠数值模型,验证了滑动角计算方法的准确性。首先,基于节圆偏移产生机制,建立了滑动角运动学分析模型,通过与数值解对比,验证其准确性;在此基础上,分析了丝杠转速、螺母负载对滑动角大小以及螺纹副、齿轮副滑动距离的影响规律。结果表明,滑动角随着丝杠转速、螺母负载的增大而增大;滚柱-丝杠侧滑动距离远大于滚柱-螺母侧,且均随着丝杠转速、螺母负载的增大而增大;齿轮副滑动距离随丝杠转速增大而减小,随螺母负载增大而增大。

不同工艺条件对低锡量镀锡板耐蚀性的影响

为了提高镀锡板的耐蚀性,更好地满足客户的使用需求,分别研究了助溶剂浓度、合金层厚度、钝化膜厚度和配辊工艺对2.8 g/m2锡层的镀锡板耐蚀性的影响。结果表明,对于2.8 g/m2镀层的镀锡板,助溶剂浓度越低,镀锡板耐蚀性越好;合金层和钝化膜厚度越厚,镀锡板耐蚀性越好;不同的配辊工艺造成基板粗糙度的差异,粗糙度越大,尖峰分布范围越广,锡层分布越不均匀,镀锡板的耐蚀性越差。

翁结水库碾压混凝土重力坝动力特性及其抗滑稳定分析

重力坝是水利工程中最常用的主要水工建筑物之一,混凝土重力坝在地震作用下的动力稳定是坝工设计中的重要问题.本文以翁结碾压混凝土重力坝为对象,取位于河谷中的7、8号溢流坝段和9号非溢流坝段,建立三维有限元模型,通过计算分析了碾压混凝土重力坝在不同工况下的应力变形规律及抗滑稳定性.结果表明:静力荷载作用下,坝体位移符合重力坝一般规律,坝踵主拉应力范围较小;动力荷载作用下,位移等响应在坝顶达到最大,符合鞭鞘效应特征,同时坝体残余位移较小,坝体在一些部位出现瞬时拉应力超标现象,坝基塑性区未发生贯通;对7、8号坝段和9号坝段在建基面及碾压层面进行抗滑稳定验算,坝体坝基均满足稳定要求.

圆锥滚子轴承套圈辗扩成形有限元模拟

环件辗扩是轴承套圈的主要成形方法,加工质量直接影响轴承的使用性能。以圆锥滚子轴承为例,基于DEFORM建立套圈径向辗扩有限元模型,通过试验验证了模型的正确性,并分析了初始辗扩温度、芯辊进给速度和主动辊转速对套圈等效应变和温度的影响,结果表明:初始辗扩温度、芯辊进给速度增大,套圈等效应变减小;主动辊转速增大会使套圈等效应变增加;芯辊进给速度和主动辊转速增大,套圈温度升高且温度分布更均匀。

基于DOE分析法的打叶复烤长梗得率工艺优化

[目的]优化打叶复烤长梗得率工艺,提高烟草打叶复烤长梗得率。[方法]以陕甘产区的中部烟配打模块为供试材料,以打叶流量、三打打辊转速、四打打辊转速为研究对象,采用全因子试验设计及DOE,探索打叶流量、三打打辊转速和四打打辊转速对长梗得率的影响,并构建相应的数学回归模型。[结果]打叶流量、三打打辊转速、四打打辊转速3个因子主效应及打叶流量与三打打辊转速间的交互作用对长梗得率均有显著影响,而打叶流量与四打打辊转速间的交互作用、三打打辊转速与四打打辊转速间的交互作用对长梗得率均没有显著影响。长梗得率与打叶流量、三打打辊转速、四打打辊转速及打叶流量与三打打辊转速间的交互作用四者间存在有效的回归模型。最优的指标参数为打叶流量9500 kg/h、三打打辊转速650 r/min、四打打辊转速750 r/min,平均长梗得率达到最大值15.2850%,合意度最好。[结论]长梗得率与打叶流量、三打打辊转速和四打打辊转速存在一定的回归关系,通过回归关系确定了最佳长梗得率的打叶流量、三打打辊转速和四打打辊转速指标参数。

基于线结构光的牵伸罗拉工作面圆跳动测量方法

针对牵伸罗拉工作面圆跳动的人工测量精度不稳定、效率低等问题,课题组提出了基于线结构光的牵伸机罗拉工作面圆跳动测量方法。通过线结构光获取牵伸罗拉工作面的条纹图像,在条纹图像预处理的基础上采用Steger算法提取条纹图像的中线点云数据;建立基于点云的牵伸罗拉工作面圆跳动测量模型;通过构建虚拟平面,得到牵伸罗拉的圆跳动值。实验结果表明:课题组所提出测量方法的绝对误差在0.01 mm之内,小于传统测量方法的绝对误差,提高了测量精度。

基于离散单元法的双辊餐厨垃圾破碎机产物粒径影响因素仿真分析

餐厨垃圾的处理包括对餐厨垃圾实施破碎、压榨、分选等操作,以实现固体破碎、固液分离、油水分离,进而达成无害化处理或资源回收利用目的。双刀辊破碎装置是实现餐厨垃圾固体破碎的高效设备之一,其作用是将大块物料粉碎成粒径细小且均匀的物料颗粒,以便于进行后续处理和存储运输。基于离散单元法,采用仿真软件EDEM的Edinburgh Elasto-Plastic Adhesion和Tavares UFRJ Breakage接触模型,模拟了双辊转速分别为10、15、20、25、30 rad/s和物料颗粒初始半径分别为10、15、20、25、30 mm时破碎装置的工作情况。结果表明:刀辊转速和初始颗粒半径都对破碎装置的破碎效率及出料颗粒粒径分布具有显著影响;双辊转速越快,完成破碎作业所需时间越短但出料颗粒里小粒径占比会降低;入料半径15 mm时作业效率最高,而入料半径30 mm时出料颗粒里小粒径颗粒占比最高。

基于有限元的风电机组双列调心滚子轴承变精度建模方法

为提高风电机组主轴双列调心滚子轴承接触应力的计算精度,以某2 MW陆上风电机组主轴双列调心滚子轴承为研究对象,提出一种基于有限元的轴承变精度建模方法,通过建立低精度的轴承模型得到其接触应力分布,再根据最大接触应力位置建立关键区域的高精度子模型,实现最大接触应力的精确计算。通过对位移、接触应力的收敛性验证得到最佳子模型宽度和网格数量,并通过虚拟阻尼法的收敛性、子模型精度、最大接触应力以及径向游隙对内、外圈最大接触应力的影响验证了模型的正确性。