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.

Gating system optimization of high pressure die casting thin-wall AlSi10MnMg longitudinal loadbearing beam based on numerical simulation

High pressure die casting(HPDC) is a kind of near net shape manufacturing method. However, air entrapment in HPDC parts has serious effects upon the casting quality. In order to reduce the air entrapment defects in a AlSi10 MnMg alloy thin-wall longitudinal load-bearing beam produced by HPDC, different gating systems were designed and simulated by software Flow-3D to evaluate the entrapped air. Simulation results showed that when the beam is produced by the original designed gating system with a middle ingate, there exist obvious air entrapments in the critical area; the volume of air entrapment was reduced by replacing the middle ingate to an overflow well, and the filling of molten metal became more stable. When the middle ingate was removed for further improvement, the volume of air entrapment was decreased drastically. The parts with glossy surface and good microstructure have been successfully produced by using the final optimized gating system based on simulation results.

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.

Numerical simulation and optimization of shell mould casting process for leaf spring bracket

Although the shell mould casting process has a wide range of application in many fields,the prediction of casting defects is still a problem.In the present work,a typical leaf spring bracket casting of ZG310-570 was fabricated by shell mold casting.The finite element model and ProCAST software were utilized for simulating the filling and solidification processes of the casting;and the formation mechanism of the gas pore,and shrinkage porosity defects were analyzed.The results indicate that the gas pore and shrinkage porosity defects are formed due to air entrapment,insufficient feeding and non-sequential solidification.Subsequently,through changing the position of risers,adding a connecting channel between the risers,and setting blind risers at the U-shaped brackets,an optimized gating and feeding system was established to improve the quality of the casting.After optimization,the gas pore and shrinkage porosity defects of the leaf spring bracket casting are effectively eliminated.The experiment results with the optimized casting process are in good agreement with the numerical simulation,which verifies the validity of the finite element model in the shell mould casting.

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.

3-D Finite-Element Numerical Simulation of Centrifugal Induction Electrosalg Casting Solidification Process

A 3-D finite-element numerical simulation model of temperature field for CIESC casting solidification process was developed with the aid of ANSYS software and a series of corresponding experiments were made. The results showed that the good agreement was obtained between the numerical simulation and the experiments. Based on the numerical simulation results, the characteristics of temperature distribution in the castings during CIESC solidification process were analyzed and summarized. According to the G/R-1/2 method and numerical simulation results, there is no any shrinkage defect in the CIESC casting and structure or casting is fine and compact.

Finite element analysis for die casting parameters in high-pressure die casting process

The gating system and the overflow system were designed according to the casting structure during high pressure die casting(HPDC) process. The simulation was carried out by ProCAST software to visualize the injection chamber pre-crystallization and the flow of molten metal. The main work is to research four die casting process parameters, i.e. injection temperature, low-pressure velocity, high-and low-pressure velocity’s switching position, and high-pressure velocity. Experimental results show that the higher injection temperature and lowpressure velocity can mitigate the pre-crystallization of the injection chamber. However, when the low-pressure velocity exceeds 0.2 m·s-1, the air entrapment in the chamber occurs. Besides, when the high-pressure velocity is greater than 2.5 m·s-1, the overflow channel at the final filling position is covered by the liquid metal too early. Finally, the injection temperature of 650 °C, the low-pressure velocity of 0.2 m·s-1, the high-and low-pressure velocity’s switching position of 320 mm and the high-pressure velocity of 2 m·s-1 are obtained as the optimal parameters by the software simulation, which has been verified by actual production.

Optimization of steel casting feeding system based on BP neural network and genetic algorithm

The trial-and-error method is widely used for the current optimization of the steel casting feeding system, which is highly random, subjective and thus ineff icient. In the present work, both the theoretical and the experimental research on the modeling and optimization methods of the process are studied. An approximate alternative model is established based on the Back Propagation(BP) neural network and experimental design. The process parameters of the feeding system are taken as the input, the volumes of shrinkage cavities and porosities calculated by simulation are simultaneously taken as the output. Thus, a mathematical model is established by the BP neural network to combine the input variables with the output response. Then, this model is optimized by the nonlinear optimization function of the genetic algorithm. Finally, a feeding system optimization of a steel traveling wheel is conducted. No shrinkage cavities and porosities are induced through the optimization. Compared to the initial design scheme, the process yield is increased by 4.1% and the volume of the riser is decreased by 5.48×10~6 mm3.

Novel methodology for casting process optimization using Gaussian process regression and genetic algorithm

High pressure die casting (HPDC) is a versatile material processing method for mass-production of metal parts with complex geometries,and this method has been widely used in manufacturing various products of excellent dimensional accuracy and productivity. In order to ensure the quality of the components,a number of variables need to be properly set. A novel methodology for high pressure die casting process optimization was developed,validated and applied to selection of optimal parameters,which incorporate design of experiment (DOE),Gaussian process (GP) regression technique and genetic algorithms (GA). This new approach was applied to process optimization for cast magnesium alloy notebook shell. After being trained,using data generated by PROCAST (FEM-based simulation software),the GP model approximated well with the simulation by extracting useful information from the simulation results. With the help of MATLAB,the GP/GA based approach has achieved the optimum solution of die casting process condition settings.

基于AnyCasting排气歧管砂型铸造数值模拟及试验研究

用砂型铸造生产的排气歧管汇聚多个支管,内外表面有极复杂的曲面,这对生产工艺提出很高要求,若工艺不当,会在浇注过程中产生缩松、缩孔、卷气、冷隔、夹渣等缺陷。运用AnyCasting铸造模拟软件对试制产品进行流场和温度场分析,基于分析结果预测铸件中存在的缺陷种类、位置和大小。理论分析与试验结果基本吻合,通过分析缺陷情况实施相应工艺优化,将缺陷影响降至最小程度,从而得到满意铸件。

基于AnyCasting的中座铸造工艺优化

针对中座零件的铸造工艺中常出现的问题,利用铸造仿真模拟软件Any Casting进行仿真优化,从而改进工艺,消除缺陷。通过对仿真结果分析,判断浇注过程中,在内浇道的前面容易形成卷气和夹渣等缺陷,根据软件分析结果对容易形成缺陷的部位进行优化,利用增加冒口颈与铸件的距离,减少冒口颈的直径,降低内浇道的高度,增加内浇道的宽度等方式,改进工艺。再对优化以后的铸造工艺,尤其是对充型和凝固过程进行仿真模拟,得到了较为理想的仿真结果。利用改进工艺,进行了砂型铸造试铸,中座铸件的缺陷基本消失。

基于AnyCasting的齿轮泵壳体金属型铸造工艺优化

利用AnyCasting软件对铸件原工艺方案的充型和凝固过程进行数值模拟,模拟结果表明内浇口充型速度为60 cm/s时,金属液充型平稳,但内浇口附近局部过热;内浇口充型速度为100 cm/s时,金属液有紊流产生,但内浇口附近局部过热消失。实际生产中给出以下改进措施:1)采用先慢后快的充型速度;2)在凝固阶段金属芯通水冷却。采用新的铸造工艺方案后,铸件内部缺陷基本消失。

基于AnyCasting的减速器下箱体铸造模拟及工艺优化

使用UG建立减速器下箱体三维模型。在原有铸造工艺的基础上利用AnyCasting软件模拟了减速器下箱体的充型和凝固过程。根据模拟结果分析了铸件的温度场和缺陷分布。结果表明,在原工艺方案下会出现缩松、缩孔等铸造缺陷。通过增大冒口尺寸以及添加冷铁等工艺优化,可以消除铸件内部缺陷的产生,为类似下箱体的实际生产起到了一定的指导作用。

基于AnyCasting大型薄壁鞍座铸造工艺优化

针对大型薄壁铸件鞍座铸造过程中易产生缩松、缩孔缺陷等问题,基于AnyCasting模拟软件对鞍座的充型和凝固过程进行了模拟。根据模拟结果分析缩松、缩孔缺陷的位置分布,发现铸件内部有缩松、缩孔现象产生,并通过实际浇注试验对比缺陷位置以验证模拟结果的可信性。采用在热节位置添加内冷铁的改进方案,结果表明,原缺陷产生位置在凝固过程中优先凝固,消除了缩松、缩孔缺陷,为类似薄壁铸件实际生产提供相应指导。

基于AnyCasting的叶轮铸造模拟及工艺设计优化

以材质为铝硅合金ZAlSi9Cu2Mg的某叶轮为研究对象,采用铸造工艺设计优化和数值模拟相结合的方法设计ZL111叶轮的铸造工艺方案并优化。根据其结构特征,设计浇注系统,选择树脂砂造型制芯和热芯盒砂型铸造工艺。确定浇注系统之后,采用AnyCasting软件对铸件的充型和凝固过程进行模拟,预测叶轮铸件缺陷产生的位置,发现叶轮充型过程平稳,在其中心部位出现了缩松缩孔缺陷。通过对其产生缺陷的原因分析,并对铸造工艺方案进行优化改进。最终通过模拟仿真发现通过放置冷铁可以消除叶轮铸件的缺陷,为大批量中型铸件ZL111叶轮提供了合理可行的铸造工艺方案,对其实际生产起到了指导作用,从而保证叶轮的产品质量。

基于Anycasting软件的壳体仿真分析及工艺优化

为得到高质量铸件,针对汽车转向器伺服壳体壁厚不均,结构复杂的特点,使用UG对壳体进行三维建模并使用Anycasting模拟铸造软件对壳体高压铸造充型及凝固过程进行数值模拟,改进模具结构优化压铸工艺参数,有效地预测了在压铸过程中出现的缩松缩孔问题的位置。通过正交试验与Anycasting模拟软件分析得出ADC12铝合金转向器伺服壳体优化后的压铸工艺方案:浇注温度为630℃,模具初始预热温度为180℃,压射速度为1.6 m/s。通过压铸件生产加工实验和金相试验验证了优化后的铸件质量明显提高。

铸造镁合金凝固过程数值模拟研究进展

镁合金以其轻量化、高比强度和良好的阻尼性能在汽车、航空航天等领域应用广泛。数值模拟通过再现铸造成形过程中的各类宏观和微观物理过程,可以调控组织、减少缺陷、提高力学性能和优化铸造工艺参数。本文综述了铸造镁合金在枝晶和共晶凝固组织模拟,偏析、气孔和热裂等缺陷模拟,以及力学性能预测等方面的研究现状,简要介绍了近两年在铸造镁合金成形工艺模拟方面的研究进展。最后,指出了当前铸造镁合金数值模拟研究存在的问题及发展方向。

铰链支架压铸工艺设计和优化

根据铰链支架结构进行压铸工艺设计,针对其结构特点设计了两种压铸工艺,利用Anycasting分析软件对两种工艺进行数值模拟,对比分析两种工艺方案铸件缺陷产生的位置及原因,结合实际生产条件,选择了一种较优的压铸工艺进行优化,优化内浇道和溢流槽的数量和位置,改空冷和水冷。经模拟分析及试模证实优化措施有效,满足生产质量要求。

矿用平板车车轮铸件熔模铸造工艺优化

矿用平板车车轮铸件结构复杂,在熔模铸造过程中经常会产生缩松缩孔等缺陷。通过数值模拟软件分析该铸件的浇注过程,结果显示在车轮轮辋底部存在较多缩松缩孔,严重影响了铸件质量。为降低该铸件的缩孔率,对工艺方案进行改进,同时针对浇注温度、浇注速度、型壳预热温度三个工艺参数进行优化。各个工艺参数之间对缩孔率的影响是相互的,通过正交试验获得最优工艺组合。优化后的工艺参数提升了车轮铸件的工艺质量和生产效率。

基于数值模拟的铝合金通信机箱盖压铸工艺设计与优化

以某通信机箱盖铸件为研究对象,根据铸件产品结构特点选择合适的压铸工艺参数,并设计了浇注系统。通过CAE软件对其充型过程、凝固过程进行数值模拟。结果表明,初始压铸工艺中铸件的部分位置可能出现卷气及冷隔缺陷。生产试模结果与初始工艺数值模拟结果基本一致,初始压铸工艺无法满足生产要求。对初始压铸工艺进行优化改进,并对优化后的工艺方案进行数值模拟、产品试制,卷气和冷隔现象得到大幅改善,满足生产质量要求。