The Numerical Simulation And Optimization Of Casting Process For Discharge Bowl

The discharge bowl is a key component of the tidal power devices, itsmaterial is CD-4MCu duplex stainless steel. Sand gravity casting is usedbecause of its complex structure and non-uniform wall thickness. The castingused to engender defects during the solidification process, such as hot tearing,large internal stress and shrinkage, etc. So it will result in a high rejection rate. Inorder to reduce casting defects and improve casting quality, ProCAST software isused to simulate the casting process of discharge bowl and its optimization.First of all, the influence of pouring temperature on the castingsolidification and defects is studied. To start with, the pouring temperaturesetting is1580℃, pouring time is set to30s. Result shows that hot tearingtendency is very serious at some places of casting, where the intersection ofblades and inner and outer rings. The leaves and stiffening ring severelydeformed. There are shrinkage defects appear at the bottom of casting and thetransition area of wall thickness. Keep the filling time unchanged, pouringtemperature is adjusted to1550℃and1520℃, respectively. The analysis ofexperimental results shows that hot tearing tendency, stress and strain of thecasting increase with decreasing pouring temperature, but changes slightly. Theshrinkage defects did not change significantly also.Secondly, the influence of filling time on the casting solidification anddefects is studied. Keeping the pouring temperature is1580℃unchanged, fillingtime is adjusted to60s and20s, respectively. The analysis of experimental resultsshows that the filling time has less effected on hot tearing tendency, stress, strainand shrinkage of the casting. The simulation results fluctuate in a small rangewith decreasing filling time.Finally, the chills of discharge bowl casting are optimized according tocauses and mechanism of casting defects. Adding25~35mm thick cold iron on the outer surface of T-shaped parts where the hot tearing tendency is very serious,then it is simulated. The results indicate that the hot tearing, stress and strain ofthe discharge casting is greatly improved compared with the previous. Theshrinkage result is also better at the same time.Through the numerical simulation and technique optimization of dischargebowl casting process, the defects like hot tearing is resolved basically. It plays aguiding role in the actual production. Achieve the purpose of shortening thedevelopment cycle, reducing the cost of experiments and improving the qualityof castings.