Research On Numerical Simulation Of Lost Foam Casting Process For Ductile Iron Shell Parts

Because of the interaction between foam and molten metal, the fluid field,thetemperature field and the capability of filling during the lost foam casting processare different from the conventional casting process, and the prevention from thecasting defects become more difficult. Making use of numerical simulationtechnology, the filling and solidification process of lost foam casting can beobserved visually, the cause of casting defects can be grasped, the castingtechnology parameter can be optimized, and the quality of castings can beguaranteed.In this paper, the ProE as3D modeling software, the ProCAST as numericalsimulation software, the lost foam casting process of ductile iron shell partsproduced by a foundry are analyzed and improved.Shrinkage defects always appear on the sidepiece of the ductile iron shell partsproduced by a foundry, so the casting can’t achieve requirements of usage. In orderto find out the cause of Shrinkage defects, the filling and solidification process ofactual technological process are analyzed firstly. Three-dimensional model isconstituted, after analyzing technological process; Database of casting material andcasting mold material is established, by measuring actual production condition;Reasonable heat transfer coefficient, initial condition and boundary condition aresetted up. Through the numerical simulation, that the expected effects of stepgating system of actual casting process are not reached is found, as well as thatshrinkage defects always appear on sidepiece and part of rotary of castings, onaccount of feeding ability is insufficient. The accuracy of numerical simulation wasverified by comparison between the simulated results and the result of application.In order to overcome the aforementioned problems, the original castingprocess is improved. Top gating system and circular inner riser are adopted by theimproved process, meanwhile two castings are casted in a sandbox, the castingyield is about67%,the pouring temperature is about1480℃and the vacuity is-0.06Mpa.By the numerical simulation of the improved casting process, that thefeeding ability of riser is sufficient can be found, as well as that the castings are solidified gradually from the bottom to the center of the riser. No shrinkage defectsare distributed in the casting, only a small amount shrinkage defects appear in theriser. Castings produced by the improved casting process have well quality, andachieve requirements of usage. Therefore, that adopting numerical simulation toanalyze lost foam casting process is feasible.