The lost foam casting process of nodular cast iron was studied by using ProCAST software and visual environment software. The following conclusions are obtained:
- The special parameter settings of lost foam casting molding process and solidification process of nodular cast iron simulated by ProCAST are studied. The effects of lost foam casting model parameters and nodular cast iron micro model parameters on the simulation results are analyzed through examples. It is determined that the flow field and temperature field of filling process are calculated by thermal + flow coupling when simulating the process of nodular cast iron lost foam casting, The temperature field at the end of mold filling is extracted and coupled with thermal + micro to calculate the temperature field of solidification process and the general treatment method of shrinkage and porosity.
- The process analysis of a nodular cast iron long fork casting is carried out, and the trial production schemes of bottom injection and top injection are put forward. The mold filling and solidification processes of the two schemes are simulated by ProCAST. The results show that the two trial production schemes can not solve the problem of significant shrinkage and porosity and achieve good slag discharge and exhaust. By comparing the simulation results with the experimental results, the thermophysical model for accurately calculating the mold filling and solidification process of the example is established.
- According to the structural characteristics of the long fork and the two trial production results, a step-by-step improvement scheme is formulated. Based on the obtained thermophysical model, the forming process of the improved scheme is simulated by ProCAST. The simulation results show that the improved scheme can solve the problem of significant shrinkage and porosity, but there is a small amount of shrinkage and porosity; Through pouring verification, the stepped scheme can eliminate shrinkage defects, but there is still a small amount of concentrated shrinkage porosity in the lower part of the casting; According to the discussion conclusion on the influence of different sand molds on the shrinkage cavity and porosity defects of nodular cast iron, a new process of embedding ferrochrome cold sand in the upper and lower wall cavities of the stepped scheme and the stepped holes of the cylinder is proposed. The final pouring test results show that the new process can minimize the shrinkage cavity and porosity problems in the castings.