【作者】 陈亚娟；

【导师】 陈立亮； 刘瑞祥；

【作者基本信息】 华中科技大学 ， 材料加工工程， 2005， 硕士

【摘要】 消失模铸造作为一种精确成型技术,由于其诸多的优点,被誉为二十一世纪的绿色铸造工程,具有广阔的应用前景。消失模铸造充型过程中,由于泡沫模样气化分解及与金属液之间的相互作用,导致金属液充型时的流动场、温度场、充型能力等都与传统铸造有很大不同,并在充型过程中产生一些铸造缺陷,阻碍了消失模铸造的进一步发展。采用计算机数值模拟技术,可以不受试验条件的限制,定性、半定量地研究金属液的充型过程及各种因素的影响规律,预测铸造缺陷的产生。本文根据消失模铸造技术的特点,对消失模的充型过程进行系统分析,并结合数值求解方法,开发出消失模铸造充型过程的CAE 软件系统。本文首先通过分析消失模铸造的充型过程,并对充型过程的模拟做了一些必要的简化。在分析已有界面推移模型的基础上,综合考虑金属液流动时受到模样分解产生气体压力的阻碍作用,建立了将气隙压力作为流动前沿的边界条件进行计算的界面推移模型。在进行消失模铸造充型过程的耦合计算时,建立了合适的数理模型,利用有限差分法进行数值求解。考虑金属液前沿受到模样分解时强的激冷作用,以及金属液的辐射散热,并以此作为边界条件进行计算。本论文以数值模拟技术为基础,结合实际生产的需求,开发出相应的消失模充型过程的数值模拟软件。通过对比典型试件在消失模铸造方式下以及普通铸造方式下的模拟结果,并具体分析了轮毂铸件在消失模铸造下的充型过程,较好的验证了该软件分析计算的可靠性以及数学模型。该软件能够成功的模拟出金属液充型过程中界面推移的过程以及温度分布状态,能够在一定程度上对铸件质量进行有效的控制。更多还原

【Abstract】 The lost foam casting (LFC) technique is taken as the green engineering of foundry industry for the 21st century. It’s one prosperous technique of the exact shape of casting process. Because of the decomposability of polystyrene pattern and the reaction with the molten metal during the lost foam casting process, the fluid field, the temperature field and the capability of filling are different from the conventional casting process. Casting defects will appear and this will hold up the further development and application of this technique. Using the simulation techniques, the mould filling process and the influence of many facts can be studied qualitatively, without the bound of the experimental conditions. It can also forecast the casting defects. In this paper, the CAE system of the LFC was developed based on the characteristics of the mould filling process, using the numerical techniques. The mould filling process was simplified based on the phenomena during the LFC. The metal front advance model was developed by analyzing the existing moulds, using the gas pressure between the metal front and the foam as one of the boundary conditions to calculate the metal front. A numerical model is developed to simulate the lost foam casting process,using the finite difference method to solve the governing equations. The cooled metal front and the radiation of the metal were considered to be the boundary conditions. The foundry CAE system of the LFC has been developed combining with the real product. Comparing the simulation result of the LFC with that of the conventional casting process, the characteristics of the LFC have been validated. The CAE system can simulate the metal front advance and the temperature distribution during the mould filling process. It can also control the casting quality effectively.更多还原