On Numerical Simulation of Casting in New Foundries: Dynamic Process Simulations

New and more complex casting technologies are growing, and foundries are using innovative methods to reduce cost and energy consumption and improve their product qualities. Numerical techniques, as tools to design and examine the process improvements, are also evolving continuously to embrace modelling of more dynamic systems for industrial applications. This paper will present a fresh approach towards the numerical simulation of dynamic processes using an evolving and dynamic mesh technique. While the conventional numerical techniques have been employed for these dynamic processes using a fixed domain approach, the more realistic evolving approach is used herein to match the complex material processes in new foundries. The underpinning of this new dynamic approach is highlighted by an evolving simulation environment where multiple mesh entities are appended to the existing numerical domain at timesteps. Furthermore, the change of the boundary and energy sources within casting process simulations have rationally been presented and its profound effects on the computational time and resources have been examined. The discretization and solver computational features of the technique are presented and the evolution of the casting domain (including its material and energy contents) during the process is described for semi-continuous casting process applications.

Semi-Solid Rheological Squeeze Casting Process of ZL114A Aluminum Alloy Thin-Wall Complex Casting

High-strength aluminum alloy with large-scale and thin-walled complex castings have broad application prospects in aerospace, weapons, electronics, defense and military industries. However, due to the uneven thickness of the plate, the casting defects are inevitable by the ordinary casting method, and it is impossible to accurately control the shape and performance of the casting in the casting process. Previous studies have found that the semi-solid rheological extrusion casting technology with short process and near-end type can help solve this technical problem. Therefore, this paper studies the semi-solid rheological extrusion casting process of thin-walled complex casting of ZL114A aluminum alloy. The combination of numerical simulation and experimental research is used to simulate and optimize the filling and solidification process of thin-walled specimens. Based on this, a semi-solid rheological extrusion casting test was conducted. The result showed that, (1) The optimized model can well reflect the filling and solidification process under different rheological extrusion casting parameters, and obtain defect-free castings through process optimization. (2) The thin-walled parts of the thin plate casting produced by semi-solid rheology extrusion have excellent mechanical property and ductility.

Fast Prediction Model for Closure Pressure in Hot Isostatic Pressing

Simulation of hot isostatic pressing (HIP) process with complex castings was rarely referred for its time-consuming and difficulties existed in meshing by commercial software. A fast prediction model was proposed to overcome those limitations in present work. The relationship of holes size, shape, and closure pressure was established by analysing the closed hole in ZTC4 castings with simple structures based on the software. Then the fast prediction model was applied to a complex casting. A relative error of 4.09% was obtained between this model and result calculated by the software, which verified its effectiveness in predicting ZTC4 castings with complicated structures.

Fast Construction of the Implicit Surface for Complex Casting Geometries

Computational simulation relies on valid and accurate representations of the geometry of objects being simulated. However, the Stereo Lithography (STL), one of the most commonly used formats for computational simulation, may be invalid with several kinds of defects when the geometry is too geometrically and topologically complex. In many cases, castings have the most complicated geometries in the world, and its geometries in STL format always contain some defects. The implicit surface is a much more robust geometry representation than STL. With the representation in the implicit surface, most of the defects in STL can be cleared and ignored. This paper presents a method to fast construct the implicit surface for arbitrary complex casting geometries in the format of STL.

Numerical Simulation of Gas-Liquid Tow-Phase Flow During Complex Mold Filling Process

In order to predict defects of a complex casting that may arise during the die casting, The numerical analysis technique of Fluent' s VOF was used to establish the filling model. Based on the case of the wheel, it is expounded that the numerical simulation of VOF was utilized in application of casting. The five groups of simulation analysis were performed under the different pouring pressure. At last the pouring pressure has a great influence on the state of filling and the filling times are little difference. The research on pouring pressure and flow field during the casting process of wheels was conducted. The results of the study show that, when the pouring pressure is about 60000 KPa, the cavity is completely filled with the molten aluminum alloy.

Finite Element Mesh Model Analysis and Model Information Transform Method in Casting Simulation Process

High quality mesh model is the premise and key condition to get accuracy numerical simulation results in casting process. However, it is usually difficult to build effective mesh model by professional casting simulation software ProCAST if solid model is too complex. Finite element mesh model transferring method has been introduced in this paper to transfer high quality mesh model into ProCAST by element imaging algorithm. With the help of the powerful meshing function of Pro/E, UG and ANSYS, the nodes and elements information has been picked up and image to new mesh model which is compatible with ProCAST. By this way, high quality mesh model can be introduced into casting process numerical calculation easily. It provides an effective and efficient way for the complex casting finite element mesh model.