Numerical Simulation And Optimization Of Casting Process For QT450-10Car Differential Case

The differential case is the power transmission device that allows two drivingwheels of vehicle operating at different speed. When a car is running, thedifferential cases will be subject to high impact load. In this paper, the castingprocess of differential case of ductile iron is studied. The mould filling process andsolidification process of the ductile iron differential case were simulated by usingInteCAST software. The creating location and cause for formation of shrinkage inthe casting process were analyzed in order to obtain an optimizing casting process,for the purpose of eliminating the shrinkage defects and improving the quality andyield of the differential case.First of all, according to the structural characteristics and requirements on thematerial of left and right differential case, the preliminary design of their individualcasting process was made. Then their solidification process under the individualcasting process was simulated by using InteCAST software. According to thesimulation results, the distribution and creating cause for the formation ofshrinkage in casting process of the left and right differential case cast wereanalyzed. By varying the size of feeding riser height and riser neck respectively,three kinds of improved process for each differential case cast have been designed,and the solidification process were simulated. The simulation analysis resultsindicated that, for the left differential case cast, when the riser neck cross-sectionsize is kept168mm~2and the riser height is increased from100mm to120mm, theshrinkage defects in the casting can not been eliminated completely. But, when theriser height of is kept90mm and the cross-section area of the riser neck is increasedfrom168mm~2to300mm~2, the riser neck solidification time can been delayed. Aprogressive solidification from the casting to the riser is achieved, and the size ofthe isolated liquid zone can be eliminated significantly. When the riser diameter is70mm, the height is90mm and the riser neck cross-sectional area is300mm~2, theshrinkage defects in the left differential case castings can been eliminatedcompletely. For the right differential case, through analysis of solidification process under different process, it indicated that when the riser diameter is kept66mm and the riser height and riser neck size is increased from100mm and276mm~2to110mm and620mm~2respectively, the shrinkage defects in the castingcan been eliminated completely.Then, the simultaneous casting process of the left and right differential case inthe original production conditions has been simulated. The creating cause ofshrinkage in the thin-walled flange part of the differential case under the originalprocess has been analyzed. Combined with the optimization of the individualcasting process of left and right differential case, the simultaneous casting processhas been optimized and improved. And the simulation and analysis on the improvedsimultaneous casting process have been conducted. The results show that when thediameter, height and riser neck cross-section area of feeding riser for the left andright differential case are70mm and66mm,90mm and110mm,300mm~2and620mm~2respectively, the shrinkage defects of the left and right differential case under thesimultaneous casting process can be eliminated completely. The casting yield isincreased from60.073to71.69, which brings great benefits to the enterprise.Finally, the practical casting production verification of the left and rightdifferential case has been carried out by using the optimized process which hasbeen obtained from the simulation analysis. By dissecting the practically producteddifferential case castings, it is found that the shrinkage defects in the thin-walledflange part of the differential case under the optimized process conditions has beencompletely eliminated. And the casting process yield has been increased from60.073to71.69, which improves the production efficiency and economic benefitssignificantly.