共查询到18条相似文献,搜索用时 78 毫秒
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以预测缩孔缩松判据G/√R为基础,经过转换、推导,得出适合于几何模拟的新判据(dM/dL),√M,并编制了预测缩孔缩松的几何模拟软件,这种预测方法操作简单,计算迅速,可对铸件工艺图上指定部位进行预测,与模数法设计铸造工艺相辅相成。 相似文献
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对空心钢锭凝固过程的温度场进行了有限元分析。讨论了芯部传热系数、耐火材料工对厚终凝固位置、内筒壁最高温度及缩孔疏松的影响,并研究了耐火材料典型部位的温度随凝固时间的变化。通过凝固过程的温度场的模拟分析,对空心钢锭缩孔、缩松进行了预测,提出了工艺改进措施。 相似文献
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在分析了铸件凝固过程结晶潜热释放和缩孔、缩松形成条件后,应用数值模拟软件模拟了砂芯铸造汽轮机阀体的凝固过程,得到阀体铸件凝固的温度梯度分布,并预测了铸件出现缩松、缩孔缺陷的部位。在此基础上,对铸件凝固过程进行了阐述。数值模拟结果可供阀体铸造工艺设计参考。 相似文献
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铸件凝固过程孤立域动态划分及缩孔缩松数值模拟 总被引:2,自引:0,他引:2
在铸钢件实际生产中,一般凝固过程同时存在着多个熔池孤立域,而各熔池孤立域的补缩行为只限于各自孤立的熔池中.利用“虚拟传热技术”,开发了一种铸件凝固过程数值模拟动态判定孤立熔池域的方法,快速而方便地实现了凝固过程存在多个可补缩域的判别.由此根据凝固过程收缩发生的区域,准确地进行缩孔缩松的预测.可有效地解决凝固过程中同时存在任意多个孤立补缩域的缩孔缩松预测,解决了凝固过程数值模拟中常出现的位置较低的侧暗冒口或铸件中可能出现的缩孔不能被正确预测的技术难题. 相似文献
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分析了中空钢锭凝固过程中压缩空气与中心芯子间的对流传热,通过确定二者间的传热系数及压缩空气的温升,结合普通钢锭的数值模拟方法,建立了中空钢锭凝固过程的数值模拟方法,为实现中空钢锭铸造工艺参数的优化设计及中空钢锭的国产化奠定了基础。 相似文献
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Solidifi cation shrinkage has been recognized as an important factor for macrosegregation formation. An arbitrary Lagrangian–Eulerian(ALE) model is constructed to predict the macrosegregation caused by thermal–solutal convection and solidi-fi cation shrinkage. A novel mesh update algorithm is developed to account for the domain change induced by solidifi cation shrinkage. The velocity–pressure coupling between the non-homogenous mass conservation equation and momentum equation is addressed by a modifi ed pressure correction method. The governing equations are solved by the streamline-upwind/Petrov–Galerkin-stabilized fi nite element algorithm. The application of the model to the Pb-19.2 wt%Sn alloy solidifi cation problem is considered. The inverse segregation is successfully predicted, and reasonable agreement with the literature results is obtained. Thus, the ALE model is established to be a highly effective tool for predicting the macrosegregation caused by solidifi cation shrinkage and thermal–solutal convection. Finally, the effect of solidifi cation shrinkage is analyzed. The results demonstrate that solidifi cation shrinkage delays the advance of the solidifi cation front and intensifi es the segregation. 相似文献
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根据有限元模拟原理,基于ANSYS软件环境对机车车轮大型铸钢件的凝固进程三维非稳定温度场进行了数值模拟.通过有限元模拟的反馈信息进行了铸件凝固工艺的优化设计.模拟结果表明,按照传统的比例计算法设计的冒口系统能够保证铸件产品的质量,但冒口数目多,铸件工艺出品率偏低.如果单纯减小冒口尺寸以提高工艺出品率,则车轮铸件的顺序凝固条件将会受到破坏,导致缩孔缩松缺陷产生.通过减少冒口数目并设置冷铁,则可通过冒口和冷铁的联合作用,既保证无缺陷凝固工艺过程的实现,又能提高工艺出品率.通过模拟优化的实施,预测工艺出品率将提高12%. 相似文献
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C.W.Ma H.F.Shen T.Y.Huang B.C.Liu 《金属学报(英文版)》2004,17(3):288-294
A mathematical model coupling the momentum, energy and species conservation equations was proposed to calculate the macro-segregation of Fe-C alloy ingot during solidification. The corresponding simulation software which concurrently solves the macroscopic mass, momentum, energy and species conservation equations has been developed by applying the SIMPLE algorithm. The thermo-solutal convection in a NH4 Cl-H2O ingot is verified and the result shows good agreement with that reported. Then macro-segregation in a steel ingot is simulated by using the developed program. The steel ingot is in a rectangular mold with a riser. The fluid flow is mainly induced by the temperature field and the solid fraction. The macro-segregation pattern is mainly affected by the thermo-induced convection in the mushy zone. The negative segregation forms along the walls of the casting. The positive segregation forms at the top center of the casting into the riser. The species concentration reaches the peak in the center of the ingot where solidification ends lastly. 相似文献
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本文在等效液面收缩法和孤立域法基础上建立了预测铸钢件缩孔的新方法-多热节和即缩即补方法,该法实现了对模拟铸件各热节的内部动态瞬时补缩,并采用该方法对两个实际铸钢件进行了缩孔分析。 相似文献