Application Of Lost Foam Casting Process For Ductile Iron Shell Based On ProCAST

Rotary driving devices are widely used as an important equipment in aerospace,military,photovoltaic power generation and other fields due to high degree of integration.QT450-10 shell structure as a basic component requires high load-bearing capacity,impact resistance,cushioning,etc.Nevertheless,defects such as carbon defects,shrinkage and porosity,slabs defects,etc.are easily existed during the molding process of ductile iron castings.Based on the material properties and the advantages of lost foam casting,combined with the lost foam casting process and its unique molding conditions,casting simulation software ProCAST was used to simulate casting process of ductile iron shell castings.It aims to reduce the casting defects of ductile iron,improve the quality and performance of castings.According to the technological structure requirements of the rotary driving shell casting,a three-dimensional geometric model was established using Pro/E.The requirements and methods for lost foam casting were studied and the casting simulation software ProCAST was used to simulate the production and casting.The comparison experiment results obtained a reasonable process plan.The main work is as follows:Lost foam casting process preparation includes sample production analysis,coating requirements and dip coating process,modeling materials and dry sand negative pressure system.The trial-production results show that: the coating for lost foam casting considers multiple water-based coatings from the aspects of gas generation,environmental protection,and coating;under the same negative pressure conditions,the mold rigidity is important to conditions of shrinkage and porosity of expansive alloy castings that occur during solidification.Combined with the lost foam casting theory to determine the casting process plan,process parameters,design and calculate the riser system and pouring operation and impact.The simulation results show that the design freedom of the riser for the lost foam casting is high,and both the bottom-injection and middle-injection can successfully complete the filling and solidification process.Meanwhile,the bottom pouring process cannot meet the feeding requirements without the riser process.The process structure needs to be adjusted to optimize the simulation results.The calculation parameters were set in the Visual Environment integrated environment,and solved by ProCAST.The simulation results of bottom injection and middle injection were compared,and the dynamic process and thermophysical model of the revolving shell driven molding simulation were established.The results show that the bottom-injection and middle-injection cannot meet the requirements,and carbon defects,shrinkage and porosity and other problems were serious.Aiming at the seriousness of shrinkage and porosity,the complexity of middle-injection structure,combined with the theory of lost foam casting,improve the process scheme,the problems of shrinkage and porosity and carbon defects can be solved to a great extent by adopting the form of “taking the cast to replace”.Castings are cleaned,heat treated,and inspected.The results show the casting acquired meets the technological and quality requirements.