Special setting of casting defect simulation of shrinkage cavity and porosity of ductile iron based on ProCAST

Graphite expansion will occur in the solidification process of iron castings. While the liquid metal shrinks, the graphite expansion in the mold can play the role of feeding. How about the effect of this expansion and feeding? We can simulate it in two ways with ProCAST. The first is to modify the density curve of the material, and modify the density curve below the expansion temperature of the cast iron material parameters to make it consistent with the actual effect. This method is very difficult to operate and requires sufficient experience and experiments to obtain more accurate results. The second method is adopted, that is, Coupling Microstructure calculation in the process of casting solidification calculation. The simulation of graphite expansion is realized by calculating the changes of microstructure and density at each point. This method is practical and feasible. Although many parameters are considered, the results in line with the actual situation can be obtained through certain adjustment. At this time, poros = 1 in thermal is required. Using ProCAST micro module, we can set different process parameters on site, and adjust these parameters to achieve the real casting conditions of pore formation.

The electronic rotor and gating system of a nodular iron 400 are shown in the figure. The nodular iron casting is cast by shell coated sand process. There are serious shrinkage casting defects in the large end of the main shaft in the production process. Using the operating parameters shown in the figure, ProCAST is used to simulate the casting with thermal coupling micro to judge the location and size of shrinkage casting defects.

Figures 1 and 2 show the three-dimensional model and grid model of the motor rotor and gating system assembly respectively. From Figure 2, we can see the positional relationship between the casting and shell shape, as well as their materials. As shown in the figure, the larger the volume shrinkage defect of the casting rotor is, the smaller the volume shrinkage defect in the middle of the casting runner is, which accounts for about 3.78% of the final shrinkage defect of the casting runner. The measured volume shrinkage defect of the rotor is about 3.3%, The volume is about 1.52 cubic centimeters.

Figure 4 and figure 5 respectively compare the physical cutting results of the motor rotor defects with the simulation results, customize the appropriate cutting angle and cutting plane in VISAUL viewer, and get the results close to the actual cutting results. From the figure, it can be seen that ProCAST accurately judges the location and range of the shrinkage casting defects of the nodular iron motor rotor, Based on this judgment, engineers can quickly and accurately complete process improvement and quality control.

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