Shrinkage cavity and porosity defects are common defects in casting production. One of the purposes of numerical simulation of casting solidification process is to track and predict the formation of shrinkage cavity and porosity defects in casting solidification process, so as to realize the control of internal quality of castings. For different alloys, due to their different solidification characteristics, the mechanism of forming shrinkage porosity and shrinkage porosity defects in the solidification process is also different, so the criteria used for the formation of shrinkage porosity and shrinkage porosity defects in different alloys are also different. The general idea is to calculate the hot spot of the isolated region on the basis of the temperature field, calculate the total shrinkage of the isolated region according to the liquid-solid state of the grid unit in different isolated regions at different times, and comprehensively predict the size, shape and formation position of shrinkage cavity and shrinkage porosity defects.
The rapid calculation method of isolated region in the solidification simulation of sand castings is designed, which can quickly calculate all the isolated region heat nodes in the solidification process of various sand castings, and improve the rapidity and accuracy of defect calculation in the future. Based on the calculation of temperature field and isolated region, the prediction program of shrinkage porosity and shrinkage cavity of general sand castings and nodular iron castings is completed to realize the function of defect prediction.
The calculation speed is faster than that of domestic numerical simulation software, and the calculation accuracy is basically the same as that of domestic numerical simulation software, but there is still a certain gap in specific problems compared with foreign software. The reason is that the defect prediction principle is different from that of domestic and foreign software. From the simulation results, the foreign software is more realistic, which also determines a development and improvement direction of this software and domestic numerical simulation software, and studies a more accurate and faster defect prediction method.