Numerical simulation of mould filling process for pressure plate and valve handle in LFC

In lost foam casting (LFC), the distribution of polymer beads during the bead filling process is not uniform, and the collision between polymer beads determines the distribution of two-phase flow of gas and solid. The interaction between the gas and solid phases reveals as coupling effect of the force that gas exerts on particles or vice versa, or that among particles. The gas-solid flow in filling process is nonlinearity, which makes the coupling effect an essential point to carry out a simulation properly. Therefore, information of each particle's motion is important for acquiring the law of filling process. In bead filling process, compressed air is pressed into mold cavity, and discharged from gas vent, creating a pressure difference between outer and inner space near the gas vent. This pressure difference directly changes the spatial distribution and motion trace of gas and solid phases. In this paper, Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) are employed to simulate the fluid dynamic character based on Newton's Third Law of Motion. The simulation results of some casting products such as pressure plate and valve handle are compared with the result obtained from practical experiment in order to test the feasibility of DEM. The comparison shows that this DEM method can be a very promising tool in the mould filling simulation of beads' movement.

NUMERICAL SIMULATION OF CASTING'S MOLD FILLING PROCESS

Numerical simulation of casting＇s mold filling process is the main and the most important aspect of the foundry CAE technology. But it is time-consuming; it may take dozens of hours or several days. While with the development of computer hardware, numerical simulation of casting＇ s mold filling process has made rapid progress. The simulation results, therefore, have become more and more practical. This study tries to find some clues of the computational time of mold filling process. Firstly, this paper introduces mathematic model and the basic route of numerical simulation of casting＇s mold filling process. Then the computational time of mold filling process has been carefully studied, and some new and useful results have been gained from the study of the computational time. Finally, this paper has given some real applications of numerical simulation of casting＇s mold filling process.

Numerical simulation and analysis of mould filling process in lost foam casting

In lost foam casting(LFC)the foam pattern is the key criterion,and the filling process is crucialto ensure the high quality of the foam pattern.Filling which lacks uniformity and denseness will cause variousdefects and affect the surface quality of the casting.The influential factors of the filling process are realized in thisresearch.Optimization of the filling process,enhancement of efficiency,decrease of waste,etc.,are obtained bythe numerical simulation of the filling process using a computer.The equations governing the dense gas-solid two-phase flow are established,and the physical significanceof each equation is discussed.The Euler/Lagrange numerical model is used to simulate the fluid dynamiccharacteristics of the dense two-phase flow during the mould filling process in lost foam casting.The experimentsand numerical results showed that this method can be a very promising tool in the mould filling simulation of beads’movement.

Numerical Simulation of Al-Si Alloys Filling in EPC Processes

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Study on Numerical Simulation of Mold Filling and Heat Transfer in Die Casting Process

A 3-D mathematical model considering turbulence phenomena has been established based on a computational fluid dynamics technique, so called 3-D SOLA-VOF (Solution Algorithm-Volume of Fluid), to simulate the fluid flow of mold filling process of die casting. In addition, the mathematical model for simulating the heat transfer in die casting process has also been established. The computation program has been developed by the authors with the finite difference method (FDM) recently. As verification, the mold filling process of a S-shaped die casting has been simulated and the simulation results coincide with that of the benchmark test. Finally, as a practical application, the gating design of a motorcycle component was modified by the mold filling simulation and the dies design of another motorcycle component was optimized by the heat transfer simulation. All the optimized designs were verified by the production practice.

Numerical simulation and processoptimization for producing large-sized castings

3-Dvelocity and temperature fields of mold filling and solidification processes of large-sized castingswere calculated,and the efficiency and accuracy of numerical calculation were studied.The mold filling andsolidification processes of large-sized stainless steel,iron and aluminum alloy castings were simulated by using ofnew scheme;their casting processes were optimized,and then applied to produce castings.

基于华铸CAE的铸造充型过程卷气缺陷定量预测研究

目的针对目前单向流数值模拟软件无法模拟卷入金属液中的气体及其演变情况的问题,开展铸造充型过程卷气缺陷定量预测研究,开发基于华铸CAE的卷气定量预测系统,深入理解铸造卷气缺陷的形成原理与运动机理,准确预测金属充型过程中的卷气量和卷气造成的气孔缺陷,为生产实践提供指导。方法提出了一种金属充型过程卷入气体搜寻与追踪算法,将卷入金属液中未经考虑的气体进行保留,从而修正单向流系统,并基于此开发了卷气定量预测系统,并对该系统进行了验证。结果应用该系统后,原本未经考虑而消失的孤立气泡被保留下来以便进行后续计算,对液体体积进行了再分配,保证修改前后液体体积守恒,并修正了金属液速度,实现了卷气定量预测系统的基本功能。结论开发的卷气定量预测系统能够考虑到卷入金属液中的气体,并对气体做出定量预测,实现金属充型过程中气孔缺陷的定量预测,对生产实践中的工艺优化有一定的指导作用。

基于砂型3D打印技术的壳体低压铸造工艺开发与验证

壳体型腔复杂且壁薄,采用传统工艺不仅造型困难,而且从模具设计到整体铸造工艺开发与验证,所用周期长、效率低,生产成本高。基于砂型3D打印技术快速制样优势,本文对壳体浇注系统采用随形设计方案,实现了型腔、叶片一体化结构成形制造,结合数值仿真计算分析,对浇注工艺进行设计优化,开展了浇注试制与铸件实物检测。结果表明,选用3D打印砂型整体成形工艺可实现复杂结构壳体的短周期、低成本与高精密制造,实现工艺样件的快速制造。

大流量倒虹吸水力特性研究

为保证大流量倒虹吸能够安全稳定的输水,采用流体动力学软件(CFD)对某工程三维数学模型进行数值模拟,并结合物理模型试验,分析了倒虹吸充水过程中水流变化特点和稳定后的水力特性。结果表明,倒虹吸水流流速最大位置位于管道下坡段,压强最大位置位于管道水平段;充水过程中,倒虹吸边部管道内水流流速较中部水流大8%左右;在水流稳定后倒虹吸下游闸室后存在卡门涡街现象,造成水流流态紊乱,导致下游水面震荡,需要对下游闸墩进行延长或进行墩头结构优化,以减轻涡街强度和水面震荡的影响。

灌胶贴合过程的数值模拟研究

灌胶贴合工艺已大量运用于超大尺寸贴合中,但其工艺参数的理论研究不足导致验证较为复杂。基于流动力学的基本方程,在合理假设的前提下,提出理论计算模型,并用数值分析软件进行模拟,得出工艺最佳参数。结果表明,设计的理论计算模型与实际流型基本一致,灌胶时间有10 s的误差,满足实际应用的精度要求,利用该模型可以探索灌胶贴合工艺参数的变化规律,从而快速确定工艺参数的最佳方案。

深部矿体机械化上向水平分层进路充填开采进路断面尺寸优选

深部矿体地质条件复杂,在应用机械化上向水平分层进路充填法开采时,合理选取进路断面尺寸对于矿山安全生产具有重要的现实意义。以云南某铅锌矿深部中段首采分段为工程实例,综合考虑经济、安全、劳动强度和环境4个指标,利用层次分析法初步筛选开采进路断面尺寸,其后针对初选结果,利用FLAC^(3D)数值分析软件模拟深部中段首采分段4个分层的回采,以优选适于该矿深部矿体机械化上向水平分层进路充填法的进路断面尺寸,结果表明:3 m×3 m和5 m×5 m的进路断面尺寸在层次分析法中的优劣排序靠后,故先行淘汰;通过首采分段周边矿岩最小主应力、塑性区和垂直位移的综合对比发现,3.5 m×3.5 m和4 m×4 m的进路断面尺寸可较好地适应该矿深部矿体机械化上向水平分层进路充填法开采。层次分析法初选和数值模拟优选相结合的方法,可为同类型矿山进路断面尺寸优选提供借鉴。

铸件充型凝固过程数值模拟发展现状

铸件内在质量很大程度上取决于铸件的充型和凝固过程。将计算流体力学、计算传热传质学和计算机可视化技术应用于铸造工艺设计 ,可以使铸造技术人员更清楚地了解铸件形成过程 ,快捷地确定较为合理的铸造工艺参数。本文对铸件充型和凝固过程的数学模型、计算方法及商品化软件方面的发展现状进行了综合评述 ,并展望了该领域的发展前景。

铸造充型过程数值模拟的研究进展及应用

铸造过程的计算机数值模拟是当前公认的材料科学领域重要的研究课题,而充型过程的模拟是其中的难点之一.本文回顾了充型过程数值模拟技术的发展历程,综述了充型过程数值模拟技术的最新进展.简要介绍了目前国内外模拟软件的发展情况.针对"Z-CAST"系统阐述了数值模拟软件在铸造生产中的应用.

消失模铸造与普通铸造充型过程特点的数值模拟对比分析

利用数值模拟技术,分析对比了四种铸件消失模铸造和普通空腔铸造充型过程的差异,以及流动进程中的温度场分布的差别。结果表明,消失模充型顺序与普通空腔铸造充型顺序大为不同,消失模流动过程的热量损失较普通空腔铸造热量损失大得多。同时发现,在消失模铸件表面容易因残余泡沫而造成表面渣气孔,实际铸件的表面质量也证明了这一点。针对消失模的这些特点提供了改进工艺的实例。

提高充型过程数值模拟运算速度的动态超松弛迭代算法

在模拟铝合金压铸件型腔充型过程时 ,采用传统的固定松弛因子ω(0 <ω <2 )不能有效地减少运算中的迭代次数 ,而采用一种提高充型过程数值模拟运算速度的新算法—动态超松弛迭代算法 ,在 0 <ω <2范围内 ,运用自适应计算方法 ,根据运算的迭代次数的增减可以决定松驰因子的增大或减少 ,动态调整松弛因子可使运算中的迭代次数减少。经实际运算检验 ,运用该方法可以大幅度提高运算速度 ,运算的迭代次数减少 2 5 %。

大型磨台铸钢件的数值模拟与工艺优化

利用数值模拟软件ViewCast对某大型铸钢件磨台的凝固过程进行了数值模拟,预测了磨台产生缩孔缩松缺陷的位置。根据模拟结果初步设计了磨台的补缩系统工艺方案,对设计的工艺方案进一步模拟优化,获得了合理的补缩系统工艺方案,并在实际生产中,获得了良好的效果。

低温液体充填管路的数值计算

在低温液体的管路输送中,充填过程是一个使管路热负荷大幅减少的预冷却阶段,了解其特征规律非常重要。本文通过建立一维模型,对水平液氢加注管的预冷过程进行了数值计算,求得了各时刻管路的壁温分布,以及预冷却过程所用的时间。初步分析了低温液体充填管路过程中,管壁与工质的温度分布特点,以及管路长度、管径与加注流量对预冷却时间的影响。

熔模精密铸造蜡模充型过程的数值模拟

对熔模精密铸造模料的流变特性和充型过程进行了分析 ,确立了模料充型过程数值模拟的数学模型。利用计算机数值模拟技术 ,建立了相关的软件系统。对端盖铸件的蜡模成型过程进行了模拟 。

消失模铸造充型过程数值模拟

运用PROCAST软件对板形铸钢件的消失模充型过程进行了数值模拟。考察了阶梯式浇注系统的充型顺序以及底注式浇注系统的充型形态 ,另外研究了底注式浇注系统的浇注速度对缺陷形成的影响。模拟结果表明 ,消失模铸造中 ,金属液优先从阶梯式浇注系统的上层内浇道充型 ,充型前沿流动紊乱 ,铸件容易出现气孔或夹渣 ;对于底注式浇注系统 ,充型前沿的流动相对平稳 。