梯度石墨铸铁玻璃模具液态模锻模拟与仿真

为解决传统砂型铸铁玻璃模具铸件工艺出品率低、缩孔缩松等问题,采用液态模锻工艺成型,通过不同的冷却条件实现铸件石墨形态呈梯度分布。利用Procast对液态模锻过程的温度场和凝固场模拟,对缩孔缩松缺陷进行了预测,对浇注温度、冷却方式、浇口尺寸等关键工艺参数进行了调整优化,并根据热分析观点对铸件不同部位组织进行预测。结果表明,液态模锻可以有效减少缩孔缩松等铸造缺陷。     

界面传热系数对铸造凝固过程温度场的影响

为研究重力铸造和反重力铸造凝固过程中铸件/铸型间界面传热系数对温度场的影响,利用ANSYS有限元软件模拟了铸造凝固过程的温度场,并将模拟数据与实际测量的温度进行了对比.研究结果表明：无论是重力浇铸,还是凝固压力为17.12 kPa和30.90 kPa的反重力浇铸,对于模拟温度场与实际测量的温度场的接近程度,考虑界面传热系数要优于不考虑界面传热系数;随着凝固压力的增大,铸型/铸件界面的传热能力提高,铸件凝固速度增加,凝固时间缩短.     

高速列车转向架中心销铸造过程数值模拟

CRH380中心销是高速列车向架的关键铸件,射线探伤要达到一级标准,要求有先进的铸造工艺做保证,为此必须对铸造工艺进行优化。首先采用华铸CAE软件对初步设计的铸造工艺进行模拟,而后选择最佳工艺方案进行浇注实验,对铸件毛坯进行射线探伤、正十字解剖检查内部质量。结果表明,对于CRH380中心销铸件,采用单侧进水、热节处放置顶冒口的传统浇注工艺方案,浇注过程中卷气易在铸件中形成气孔,只在热节处安放冒口时在平板处易形成缩松;将铸件中部的中空锥体铸成实体,使热结集中并向平板方向移动,强制造成顺序凝固的条件,而后采用只设顶冒口浇注工艺方案,则除锥体心部外有少量的缩松外,其他部分没有缩松、缩孔、夹杂等缺陷,射线探伤评定为一级。铸造过程数值模拟结果与实际铸造结果基本吻合。     

铝合金壳体低压铸造工艺优化研究

采用有限元数值模拟方法,模拟铝合金壳体件的低压铸造充型和凝固过程,预测出铸件内部缺陷并提出改进工艺。研究结果表明,在砂芯位置2处嵌冷铁可消除凝固缺陷,这对该零件的低压铸造生产提供了理论指导和试验前提。     

Al-Si合金(A357)重力铸造充型及凝固过程模拟

利用多通道数据采集系统对铸件特定部位的温度进行测量,以掌握该点的凝固和补缩,并利用O lym pu s金相显微镜观察铸件关键部位的宏观组织,进而分析其凝固方式.用商业化模拟软件Z-C ast对铝合金拉伸试棒充型及凝固过程进行模拟,对实际浇注实验中测试点的温度场进行模拟,并将模拟结果与实验结果进行比较.结果表明,当金属铸型的预热温度较低时,必须采用较高的浇注温度才能够使铸型充满,试棒在凝固过程能够得到有效补缩,从而消除了由于糊状凝固造成的显微缩松.铸造模拟软件Z-CA ST能够准确的模拟铝合金铸件充型凝固过程,提供较准确的流场、温度场信息,预测缺陷及其出现位置.     

铸造CAE技术在航天产品上的应用及发展前景

铸件的凝固过程是一个复杂的高温、动态、瞬时的变化过程,在这个过程中缩孔、疏松等铸造缺陷会相继出现。利用铸造CAE技术可以在生产前发现这些缺陷的具体位置和大小,将质量隐患消灭在计算机模拟的反复比较优化中;并可有效地控制生产成本,提高铸件质量,使铸件获得很高的性价比。通过介绍铸造CAE技术在推动传统铸造向现代铸造发展中发挥的重要作用,以及在北京航星机器制造公司及其它相关企业中的应用情况,阐述了铸造CAE技术在航天产品铸造生产中广阔的应用前景。     

天然无定形石墨砂的性能及应用研究

本文较详细地研究了天然无定形石墨砂的性质及其在铸造生产中的应用,研究表明,研究表明,石墨砂具有良好的导热性和蓄热性,在铸造生产中可以促进铸件的方向性凝固,防止铸件粘砂、夹砂等缺陷。应用前最广阔。     

阶梯式浇注系统的设计原理和新计算法

前言对于中、大型铸件正确地应用阶梯式浇注系统可以做到:充型平稳,避免因压头过高而造成的严重喷射现象,金属自下而上充满型腔,有利于气体排除,不易形成气孔、冲砂等缺陷;铸件上部温度高于下部,这样的温度分布有利于顺序凝固,使铸件组织致密,并可避免浇不足、冷隔等缺陷;内浇道多而分散,避免了内浇道附近的局部过热现象等。但要求在铸件上的几个高度面上开设有内浇道的这种浇注系统浇注后,金属液体首先只从最底层内浇道     

涡轮增压器叶轮低压铸造工艺设计及优化

采用UG NX8.0对某涡轮增压器叶轮的三维立体图进行有限元网格划分,应用ProCAST对铝合金叶轮的低压铸造充型过程和凝固过程进行数值模拟,利用VisualCAST对产生的缺陷进行可视化的对比,分析浇注温度、模具温度及压力-时间参数对铝液充型状态和凝固顺序的影响,并获得合适的低压铸造工艺参数。对试铸样品进行检测,结果表明:利用ProCAST可对叶轮的低压铸造工艺进行定量优化。     

钛合金离心铸造缩孔缺陷物理模拟研究

为了深入研究钛合金离心铸造缩孔缺陷,采用微晶蜡作为物理模拟介质,按照相似准则,模拟了离心力场下钛合金凝固成形过程中缩孔缺陷,研究了旋转速度和离心保持时间对离心铸造缩孔缺陷的影响规律.实验结果表明:随着旋转速度的增加,微晶蜡凝固件冒口处缩孔缺陷体积增大;与离心保持时间900 s时相比,保持时间30 s时冒口处的缩孔缺陷体积相应减小,冒口补缩效果减弱.同时实际浇注了钛合金铸件,试验结果和物理模拟结果相吻合,验证了物理模拟试验结果的正确性.     

基于有限元法的镁铝合金薄壁压铸件压铸缺陷分析

铸造充型过程的数值模拟技术是铸造领域的前沿技术。采用这些技术进行充型过程的数值模拟可以帮助人们更清楚地了解充型过程中金属液流动的自由表面和速度分布。为了给薄壁压铸件选择最佳浇注系统和最佳工艺参数,利用PROCAST软件对铸件的压铸过程进行了数值模拟,获得了铸件充型时间和温度场的分布,根据分析结果优化模具结构和压铸工艺。     

Influence of cooling conditions in casting Cu-Ni alloy based on numerical simulation

The most common and serious defect in Cu-Ni alloy casting is porosity. To solve the problem, accurate casting design and proper design of gating system are necessary. It can be predicted and designed by means of computer simulation of casting solidification. Based on the casting process of the Cu-Ni alloy, the simulation software of diathermanous—flowing—stress coupling ProCAST was used to simulate the Cu-Ni alloy solidification process about the defects and temperature field. By combining experimental results with the simulation results, the quality of casting on some cooling conditions were analyzed. Furthermore, a better cooling condition for solidification process of the Cu-Ni alloy was chosen to improve the quality of the casting. The simulation results indicate that the quality of Cu-Ni alloy casting is the best when it is on the cooling condition of the permanent mold with the insulated riser system.     

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.     

镁合金通讯件压铸模浇注系统的设计与充型模拟

针对镁合金特殊的凝固性质和金属铸型的不透明性，借助Pro／Engineer软件，基于PlasticAdvisor模块，设计了镁合金通讯件及其压铸模锥形浇注系统，探讨了该系统在材质为AM60B合金时的浇注环境。模拟结果表明，该浇注系统填充过程平稳，温度场分布均匀，所得压铸件气体夹杂和冷隔缺陷少，整体质量较高。     

镁合金压铸件充型过程的数值模拟技术研究

针对镁合金的压铸工艺特点和充型过程的不透明性，采用Pro／ENGINEER2001进行铸件的实体造型，并生成面网格文件．利用ProCAST软件模拟压铸件充型过程的物理场，预测了镁合金压铸件的缺陷位置，从而使模具的设计过程得到了优化．模拟运行表明，采用闭合式浇注系统充型平稳，温度场分布均匀，具有较少的气体夹杂和冷隔等倾向，使得镁合金压铸件的整体质量得到提高．     

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.     

小家电压铸件充型凝固建模及仿真

通过建立铝合金烤盘压铸件充型和凝固过程的数学物理模型,对充型和凝固过程进行模拟。比较改进前和改进后方案的不同模拟结果,预测缺陷的产生,并与实际生产状况对比。结果显示,数值模拟结果较为准确,可作为改进压铸模设计的依据。由此建立的压铸模CAE体系可使产品废品率降到2%以下,模具生产周期缩短一半左右。     

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.