Numerical Simulation And Processing Optimization Of Large Complex Aluminum Die-casting

Die-casting is a metal forming process with high production efficiency, high qualityand high precision. The filling process and solidification process of die-casting can besimulated by using numerical simulation technology, and the potential defects can also bepredicted. Numerical simulation technology has important significance to improveproduct quality and efficiency in die-casting production. With the development ofautomobile industry, more and more automobile parts are produced by die-casting, andthe structures of them become more complex. Thus, there are high demands forimproving the process and numerical simulation technology of die-casting. In this paper,an automobile gearbox housing was analyzed to optimize the process of die-casting withthe numerical simulation results and practical die-casting gearbox housing production.Thereby, a method to optimize the process of large complex die-castings was proposed.Based on the large complex structure of gearbox housing, the gating system,exhausting system, die-casting mould and other initial process plan were designed.Numerical simulation of the gearbox housing was conducted, and potential defectposition and types were predicted. Compared with practical production, the accuracy ofsimulation results was verified. The defects were mainly located in the cylinder structurein the far end of gearbox housing.Then, two optimized processes were proposed and simulated. A best die-castingprocess plan was determined with the comparison of simulation results:(1) the ingatedesign was improved to keep the flow steady;(2) some troughs of overflow were addedat the proper positions;(3) the thickness of the heavy section of die-castings wasdecreased;(4) the gas content was controlled during the melting stage to reduce theporosity of die-castings;(5) optimized process parameters were determined: slow shotspeed0.58m/s, fast shot speed5m/s, pouring temperature670℃, preheated mouldtemperature190℃. High quality die-castings were produced under this optimized process.Besides, the function of porosity analysis software was completed. The accuracy ofanalyzed porosity and shape factor was improved by the modification of perimetercalculation formula, and the calculation error was kept below5%. The porosity anddistribution of holes in castings can accurately detected by this porosity analysissoftware.