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Numerical Simulation and Process Optimization of Low Pressure Die Casting Process of Aluminum Alloy Automotive Cylinder Body

Author: ChuGuoKai
Tutor: WangJinGuo；ZuoWei
School: Jilin University
Course: Materials Engineering
Keywords: Low-pressure casting Aluminum alloy cylinder block Numerical Simulation
CLC: TG249.2
Type: Master's thesis
Year: 2011
Downloads: 116
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Abstract

Casting is the molten metal pouring into the mold cavity, until their solidification, after cooling, the molding method to obtain the desired parts or blanks. However, when the process of liquid metal poured into the mold cavity, and temperature is passed to the cavity, to form the casting in the mold cavity is heated can be controlled passing a process, but also a process of heat through the mold to the outside environment . The temperature changes are important external manifestations. The internal temperature distribution of the mold and casting are changes over time. It is because in this process, the temperature variation and the distribution of the different, resulting in a internal casting defects protean. If you control the heat transfer process, the control of the internal quality of the castings is to accurately predict the casting during solidification temperature distribution and variation, that is to say can predict the internal defects of castings. But this is a very difficult thing, because from the look of the heat transfer and heat transfer process in the casting solidification process radiation, heat conduction and convection in three ways, it is a very complex process. But effective method to solve the above problem is to develop state-of-the-art casting mold filling and solidification process of numerical simulation techniques. Thesis casting simulation software PROCAST tools, simulation of low pressure die casting aluminum alloy cylinder filling and solidification process, using computer visual function, cylinder filling and solidification process, optimize the casting process, eliminating casting defects, reduce costs, and improve the yield. The main findings are as follows: 1 ProCAST software approach to solve the complex castings geometric model to the finite element analysis model of data transmission problems. And several other pre-treatment methods were compared, the results show that the use of Pro / ENGINEER modeling of Hypermesh software surface mesh of the subdivision, after the the OUT file format conversion for MeshCAST can be identified and then a volume mesh split This is a reasonable meshing pre-treatment line of work. Aluminum alloy cylinder numerical simulation of filling and solidification process, the solid fraction changes in the temperature field, flow field and the solidification process, forecasting a contraction defects. According to the simulation results and the actual production process optimization: (1) optimization of the gating system design was used to compare the different gating system design through numerical simulation of the filling process and solidification process, the impact on the quality of the casting and production efficiency, optimize casting The design of the system. Mainly on the following aspects: 1) the liquid metal filling time and clotting time; 2) liquid metal can full of mold cavity, to obtain a complete shape, a clear outline of the casting; 3) liquid metal filling process stationarity; 4) whether the formation of order conducive to the feeding of castings solidification conditions; 5) casting shrinkage, shrinkage tendency. Two ingate the introduction of liquid metal into the mold cavity, due to the long time of the liquid metal filling the mold cavity, the temperature of the liquid metal is reduced more castings can not be achieved a good filling, casting \can not be used. Within six inside the gate and ten gates to the introduction of the liquid metal casting can achieve good filling to obtain a complete shape, a clear outline of the casting, but compared to using ten gate the introduction of liquid metal and molten metal level The rise is relatively stable, casting centralized shrinkage relative decrease in size. Comprehensive analysis of ten ingate introduction of the liquid metal is relatively reasonable. (2) optimization of the pouring temperature castings according to the different pouring temperature conditions, a numerical simulation of the filling process and solidification process, the pouring temperature of the filling process of casting the main is that the temperature of the molten metal level, the higher the pouring temperature, charge type process, the higher the temperature of the molten metal level, the more favorable the filling, but also increases the possibility of a metal oxide; pouring temperature of casting solidification process, mainly affect casting solidification process of liquid metal feeding impact depends on the gate closed sooner or later, and the gate closed within casting thick and large parts of the temperature distribution at the same time, the higher the pouring temperature, the longer the casting is completely solidified time, reducing the efficiency of the production of castings . Based on the above, think that it is reasonable to pouring temperature of 725 ℃. (3) optimization of filling pressure filling pressure is an important process parameters, obtained outline clear an important role in the smooth surface of the castings. If the filling pressure is too small, easy to make castings outline is unclear, for selected 0.1bar filling pressure, too small, or even not full of mold. Filling pressure is too large castings prone to holes and other defects. Selected range should be increased filling pressure, this can increase the feeding capacity of the liquid metal, eliminating or reducing Shrinkage defects. Therefore, considering the relatively high filling pressure better solution should be selected. Therefore, filling and solidification process, the defect prediction comprehensive analysis, filling pressure 0.15bar effective than filling pressure 0.13bar. (4) Optimization of the crankshaft sand core crankshaft sand core becomes large in size, the runner to slow solidification time, the molten metal can be better feeding, thereby reducing the size of Shrinkage. Crankshaft change in the sand core is considered reasonable.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Casting > Special Casting > Pressure die casting
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