The Numerical Simulation And Process Optimization Of The Low Pressure Die Casting On Automobile Aluminium Alloy Gearbox

In China,the automobile industry has a dramatic change after several decades’development,the automotive industry is experiencing a shift from a Major automobileindustry to a powerhouse, the automotive industry has gradually become a pillarindustry of the national economy,With the rapid development of the automobileindustry，Aluminum automotive castings industry have been to rapid growth.Currently, the vast majority of automotive aluminum castings were produced byusing low-pressure casting,Compare with other castings,the low pressure castingbelongs to the special precision casting method, in order to obtain dense casting, themetal solution is applied to the relatively small pressure when the liquid metal fillsinto the mold and solidified under pressure in low pressure casting. Aluminum alloywheels and aluminum alloy box cover parts market demands are growing, lowpressure casting has many advantages, such as,the low pressure casting productionsare very well in quality,so the productions of automotive aluminum alloy castings areproduced by low pressure casting at home and abroad, and the vast majority ofaluminum alloy wheels, aluminum alloy cylinder cap are produced by low pressurecasting. Low pressure casting is also used in my paper for aluminium alloyautomobile gearbox.To produce qualified products only when the casting forming factors areeffective controlled. Traditionally, the forming process of castings were only roughcontrol on the process of castings’productions, and can only rely on the experienceand the conventional theory in the control process. The casting process of thetraditional control system has two limitations: the one is only qualitative analysis; theother is to determine the process that must be repeated trial. Accurate analysis of thefield change on our human is very difficult, so we must rely on the computer. Thecomputer obtains the change of casting forming process field through the accuratecalculation, finally gets the various parameters of the production of qualifiedproducts, these control parameters including stress field, concentration field, flowfield, temperature field and so on. An aluminum alloy A356gearbox was taken as an example to simulate thefilling and solidification process by using three-dimensional mapping softwareSolidworks to do3D modeling and ProCAST for scheduled low-pressure die castingprocess. According to the numerical simulation results of filling process on casting,itwas discovered that the surface frontier of metal liquid appeared jagged.According tosimulation and verification results, the phenomenon was caused by the irrationalgating system design. After changing the location of the gate, the liquid metal surfacewas filled smoothly. To change the original process numerical simulation on fillingsolidification mold temperature, founding die preheating temperature at350℃,gearbox casting defects was relatively better.The results showed that the reason ofproducing casting defects such as porosity and shrinkage which were found on theedge of aluminum alloy Gearbox and the gate in the scheduled process was that thepouring temperature was too high after the completion of the solidification.According to the simulation results, process parameters were optimized, and thepouring temperature was reduced to700℃,the defects were brought under controlafter the foundry process was simulated again, the quality of the casting wasimproved.When reduce the pouring speed to0.0016MPa/s, gearbox casting defectswas improved.Comprehensive analysis,we could get the best quality of castings whenthe pouring temperature was700℃,pressure speed was0.0016MPa/s,preheatingtemperature at350℃.