| In the background of energy-saving and environmental protection, lightweight design has become the main direction of automobile industry development. And because the aluminum engine has light weight and excellent heat dissipation, more and more attention has been attracted. At present, because of smooth filling, excellent performance of obtained casting and easy to form mechanization, the method of low pressure casting process is one of the most advanced methods of producing aluminum engine cylinder block. But the traditional low pressure casting process has to keep the pressure for a long time during the solidification of castings, which seriously reduce the casting production efficiency. Therefore, this paper designs a new one to make up for the weakness mentioned above. In addition, related key assemblers, equipment and parameters of the new method are analyzed by numerical simulation software.At first, the paper raises the new low pressure casting process, which removes the long-time pressure holding stage to improve the production efficiency as by separating casting filling position and solidification position. The process is as follows: when the mold is filled with metal liquid by controllable pressure, it is firstly sealed by sealing device arranged at the gate of sand mold, then lifted up and flipped 180 degrees using the turnover mechanism. Then it is moved to cooling roller and another sand mold is moved to the filling position at the same time. However, whether the turning process will cause damage to the sand mold, the paper performs a one-way fluid-structural interaction analysis of the sand mold which contains liquid metal using the finite element analysis software ANSYS. And whether the new process can produce qualified castings, the gating system and process parameters are designed, and then the process is simulated by using numerical simulation software MAGMA. The paper finally draws the conclusion as follows:(1) During the rotation of the sand mold, the maximum equivalent stress of the mold’s inner wall is about 0.45MPa, due to the impact of rotating speed and rotating acceleration. The sites where withstand greater stress are usually the interior wall of cylinder-blocks, the cylinder water jacket, crankcase and the sand core on both sides. However, the simulation results of 0.45MPa is far less than the allowable strength of the resin sand, which means the rotation of the sand mold will not cause its damage.(2) The process in this paper is designed and the related parameters are obtained as follows:The total time to fill the sand mold with liquid metal is 25s, including liquid rising stage and liquid filling stage. The former lasts from beginning to the 4th second and the pressure to fill the rising tube is 5650Pa. The latter lasts from the 4th second to the 25th second and the pressure to fill the sand mold is 14400Pa. The pouring temperature is 680 ℃. The initial temperature of cylinder linear and sand core is 300℃ and 20℃ respectively.(3) The simulation results of the new process analyzed by MAGMA show that: The sand mold is filled smoothly without splash or turbulence; Results decided by the POROSITY criterion in the software show that defects gather in the top surface of cylinder, which can be removed by machining. In summary, the new process raised in this paper could produce qualified casting. |
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