The Research On The Semi-solid Die Casting Processing And Mould Design Of AZ91D Magnesium Vehicle Part

As a near-net shape forming technology with wide application in 21 century, semi-solid metal processing technology is catching many researchers' attention in various fields. Magnesium alloy will be more and more applied in electronic, automobile and aviation industries as a green engineering material with many advantages.Gating system design and speed control play a very important role in the semi-solid die casting of high quality product. According to the specific solidification property of magnesium alloys and the opacity of the metal mould, this implies that the computer simulation techniques possess significance in guiding optimization of process parameters and die-casting mould design.The research is mainly on the research of rheological behavior of semi-solid AZ91D Magnesium alloy, the realization of hat-and-coat hook's die-casting mold CAE and the establishment of mould bases.First, apparent viscosity of semi-solid AZ91D was measured by a self-made mechanical stirring setting. The viscosity's diversification by different solid fraction and different shearing rate was studied. The results show that the rheological behavior of semi-solid AZ91D Magnesium alloy is favorable when the stirring temperature is 570°C and the shearing rate is 88.85s^-1.Second, the solid feature of the magnesium semi-solid die casting was made through the Pro/E. AnyCasting was used to simulate physical properties of the hat-and-coat hook's mold filling process. The corresponding results show that there exists much difference in the ingate size between semi-solid die casting and liquid die casting of magnesium alloy, if the ingate size was designed based on the experiences of liquid die casting, it will lead to various defects such as gas porosity, shrinkage porosity, according to the semi-solid slurry's rheological behavior. Increase the ingate size properly can make sure the semi-solid slurry obtain the laminar flow in filling process; Low shot speed and high shot speed also possess significance in semi-solid die casting, when the shot speed is too high, it will lead to wrap and reflux in filling process, when the shot speed is too slow, the filling time will be increased, and it will lead to misrun. The research also analyzed the result of different speed switch time. Based on the result, the optimization process parameters were given and experimented. Finally, based on the optimized gating system and process parameters, the mould ingredients, including the moving mold cleading, fixed mold cleading, moving mold bed plate, fixed mold bed plate, bolster plate, cushion blocks and the complementary units, are designed. Subsequently, an entire three-dimensional mold assembly diagram is completed in the actual manufacturing order.