Simulation of Temperature and Flow Field by Three Dimension Finite Element Method for Castex Process of AS Wire

Convefltionalextrudingtechnologiesmostlyatilizethelinearmovementofchiefcylinderinhydraulicpressurecrocktopushthemetalintheextrudingcontainertodeformplastically.Inordertorealizecontinuousextensioningottheingotextrusiontechnology(extrusionwithoutremain...     

Establishment and Application of A Mathematical Model for Rectangular Billet Continuos Casting

A two dimension unsteady heat transfer model is established for rectangular billet casting. Solidification process of liquid steel in secondary cooling zone was analyzed using direct difference method. The influence of operation parameters including casting speed and temperature of liquid steel was investigated. Experimental results have been used for increasing the casting speed.     

Mathematical model of solidification for round CC billets

A coupled mathematical model was established to simulate the whole solidification process of round billet continuous casting for wheel steel using piecewise linear functions of heat flux density in the mold, the secondary cooling zone and the withdrawing-straightening zone. The calculated results were consistent with the measured data showing that the model accords with the practice. The surface temperature and the solidified shell thickness of round billets are more strongly influenced by casting speed than by casting temperature. The holding zones have effect on surface temperature, which is more obvious for the 450 mm round billet. The relation between casting temperature/speed and solidification end is expressed as a linear function. The solidification end is located after straightening machine.     

钴基合金气门座圈缩松缺陷分析及改进措施

对某型号船用柴油发动机进气门座圈在生产过程中出现缩松缺陷的质量问题进行分析，从型壳的相关制作工艺和铸件的浇注工艺出发，找出缩松缺陷的产生原因，并提出相应的改进措施:采用红壳浇注，适当降低冷却速度；调整金属液出炉温度及浇注温度；增加内浇道截面积；增加内浇道与气门座圈型腔之间的圆角半径。结果表明，改进生产工艺后，缩松导致的缺陷率由原先的12%左右下降到0.5%以下。     

基于有限差分法的单晶热型连铸凝固过程的数值模拟

采用有限差分法对金属单晶热型连铸凝固过程的温度场进行数值模拟,对不同工艺组合下的液固界面曲线进行分析和比较,确定了连铸速度、冷却水流量、冷却距离、铸型温度等主要工艺参数对液固界面位置和形状的影响,其中连铸速度对凝固界面形状的影响不大,但对其位置的影响较大;改变冷却水流量和冷却距离均可调节冷却强度,相比之下,冷却距离对液固界面的影响更大;铸型温度对固液界面位置的影响较大,应进行准确控制。实际操作中可采用较小的冷却距离,同时适当提高连铸速度,保持铸型温度略高于金属熔点。     

CSP结晶器内钢液流动及凝固的数值模拟

应用数值模拟方法,建立CSP漏斗型结晶器内钢液流动及凝固传热耦合模型。针对结晶器内铸坯角部受到强冷的特点,对结晶器内热流密度采用修正方程进行计算,分析热流密度修正系数对铸坯凝固坯壳表面温度计算精度的影响。通过比较不同拉坯速率下结晶器内钢液凝固的特点,研究凝固坯壳对结晶器内钢液流动行为的影响。结果表明,采用热流密度修正系数后,铸坯凝固坯壳角部温度的计算值与实际情况更相符;提高拉坯速率可使铸坯凝固坯壳厚度减小;拉坯速率较大时凝固坯壳厚度随铸坯距弯月面距离的增大基本呈线性增长,拉坯速率为3m/min时,凝固坯壳在生长过程中厚度的增长有短暂的停滞现象;凝固坯壳对钢液流动的影响较大,主要是由钢液有效流动区域减少及两相区额外动量阻损造成的。     

Generalized constructal optimization for the secondary cooling process of slab continuous casting based on entransy theory

Based on constructal theory and entransy theory,a generalized constructal optimization of a solidification heat transfer process of slab continuous casting for a specified total water flow rate in the secondary cooling zone was carried out.A complex function was taken as the optimization objective to perform the casting.The complex function was composed of the functions of the entransy dissipation and surface temperature gradient of the slab.The optimal water distribution at the sections of the secondary cooling zone were obtained.The effects of the total water flow rate in the secondary cooling zone,casting speed,superheat and water distribution on the generalized constructal optimizations of the secondary cooling process were analyzed.The results show that on comparing the optimization results obtained based on the optimal water distributions of the 8 sections in the secondary cooling zone with those based on the initial ones,the complex function and the functions of the entransy dissipation and surface temperature gradient after optimization decreased by 43.25%,5.90%and 80.60%,respectively.The quality and energy storage of the slab had obviously improved in this case.The complex function,composed of the functions of the entransy dissipation and surface temperature gradient of the slab,was a compromise between the internal and surface temperature gradients of the slab.Essentially,it is also the compromise between energy storage and quality of the slab.The"generalized constructal optimization"based on the minimum complex function can provide an optimal alternative scheme from the point of view of improving energy storage and quality for the parameter design and dynamic operation of the solidification heat transfer process of slab continuous casting.     

镶铸复合金属材料热容量控制与研究

镶铸复合金属材料是将不同的金属材料采用镶铸工艺使它们连在一起,利用基体材料的高温液体将另一种金属合金表面熔化．使它们产生冶金结合或部分冶金结合．如何控制金属液体的温度以及合金块的结构尺寸,是本文论述复合金属材料热容量的内容．     

影响亚包晶钢铸坯表面纵裂纹的因素研究

采用金相、扫描电镜、连续测温等方法对亚包晶钢铸坯表面纵裂纹产生原因进行了系统研究,研究结果表明:当钢水过热度35℃和15℃浇铸时,铸坯表面纵裂纹发生率明显提高;随着拉速的增加铸坯纵裂纹发生率呈上升趋势;在同一拉速条件下,铸坯内弧比外弧更易于生成凹陷和裂纹;结晶器铜板热流密度不均是铸坯纵裂纹产生的主要原因,并在二冷区进一步扩展。     

Numerical Simulation of Al-Si Alloys Filling in EPC Processes

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工艺因素对消失模铸造充型前沿气膜的影响研究

运用数值模拟技术对简单板型铸铁件的消失模铸造过程进行了数值模拟,分析讨论了浇注温度、模样密度及负压度对消失模铸造中液态金属流动前沿气膜的厚度和气膜压力的影响.结果表明:消失模铸造液态金属流动前沿气膜厚度及压力随模样密度、液态金属的浇注温度的增大而增大,随沙箱的真空度的增大而减小.     

小方坯连铸二冷配水对凝固与传热的影响

研究小方坯连铸在二次冷却过程中的坯壳凝固情况,建立了传热过程的二维非稳态数学模型,计算出在整个连铸过程中温度变化和温度场分布,并得出在二冷区铸坯凝固速度与换热系数的关系.     

不锈钢板坯连铸温度场及凝固末端位置的研究

采用有限元法计算了不锈钢板坯在连铸时凝固过程中温度场及坯壳的生长随时间的变化，讨论了过热度，拉速及二冷配水量对温度场及凝固末端位置的影响。结果表明，影响铸坯温度场和凝固末端位置的主要因素是拉速和二冷配水，而过热度影响较小。     

Effects of Suspension Casting on Solidification Process of GCr15 Steel Ingot

The mechanism of inoculation in the case of suspension casting process has been studied through solidification kinetics. The effect of suspension casting process on temperature field, solidification rate, temperature gap of crystallization, effective distribution coefficient of solute and nucleation frequency during solidification process in steel ingot were discussed on the base of experiments. It has been found that the suspension casting process can increase both cooling at and solidification rate of steel ingot, improve the temperature field and solute distribution, narrow the temperature gap of crystallication, and increase the nucleation frequency. Thus, the solidification time can be shorten, the solute can be well distributied, the shrinkage porosity can be reduced and the grain of crystallization can be fined.     

镁合金汽车方向盘压铸成型工艺的数值模拟

在对镁合金汽车方向盘压铸件进行工艺分析的基础上,利用流体动力学软件Flow-3D对所设计的浇铸系统进行充型、缺陷和温度场分布的数值模拟,并根据模拟结果分析了各方案的优缺点,确定出该产品较合理的压铸工艺方案.结果表明:金属液从镁合金汽车方向盘的法兰外成端三条内浇道注入,并设溢流槽和排气槽是较佳的工艺方案.     

Mechanism of Flowing Stop of Al-Si Alloys in EPC Process

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液态模锻6061铝合金轮毂组织及性能

采用液态模锻成型时,为了研究铝合金轮毂不同部位的微观组织和力学性能,利用金相显微镜和拉伸试验机对液态模锻6061铝合金轮毂不同部位的组织及性能进行了研究.结果表明:外轮缘处晶粒最细小,而轮辐部位的晶粒最粗大;外轮缘的抗拉强度和伸长率最高,可以分别达到371 MPa和16%,轮辐部位的抗拉强度强度和伸长率最低,分别为346 MPa和9%.轮辋处的合金晶粒大小不一,且部分晶粒被拉长变形,这是由于该处糊状金属流动产生的冲刷和挤压所致.     

液态挤压工艺ANN/GA建模与优化研究

利用人工神经网络方法(ANN)建立了工艺系统模型,用遗传算法(GA)对过程参数进行优化, 实验结果与预测值吻合良好, 为预测和控制该工艺成形质量提供了行之有效的手段。     

7050铝合金热挤压成形过程的有限元模拟

针对传统工程机械用销轴数量多、重量大、工况差等不足,以7050高强轻质铝合金代替传统钢质材料,采用DEFORM-3D有限元分析软件,对7050铝合金热挤压成形过程进行有限元数值模拟,分析了挤压载荷、金属流动速率、等效应变、等效应力和温度场等参量的变化规律。结果表明,销轴的热挤压变形过程可分为4个阶段,即挤压填充阶段、开始挤出阶段、稳定挤压阶段和终了挤压阶段;工件内部等效应变分布横向均匀性较好,除了尾部变形不均匀外,其他部位应变分布基本一致;在挤压凹模模口处形成死区,工件内部等效应力达到最大值。     

硬铝合金半连续铸造过程数值模拟及裂纹倾向性研究

对凝固过程中流场、应力场、温度场及微观组织形态进行数值模拟,能帮助工艺设计人员分析不同时刻凝固过程的温度分布、金属流态、结晶晶粒尺寸、应力分布等重要物理参数,从而预测疏松、偏析、夹杂及热裂纹等缺陷.在结晶器下方设置区域冷却装置,控制区域冷却装置刮水板的作用位置,能够阻挡冷却水沿铸锭下流,实现区域冷却的效果.通过研究温度场、应力场分布规律,分析铸锭裂纹产生的原理,能够从宏观上阐明铸锭内部裂纹的形成原因及寻找有效的调节控制方法.