It mainly studies the lost foam casting of gearbox box, first carries out three-dimensional modeling, then carries out linear repair, and finally carries out grid division, parameter setting, simulation calculation and observation results by using simulation analysis software. Through the research of simulation results, the causes of casting defects in actual production are found, The pouring system and process parameters are optimized to determine the most reasonable pouring process. Through the above analysis, the following conclusions can be obtained:
1) one of the characteristics of EPC is the existence of foam pattern. Unlike ordinary sand mold, the cavity of sand mold is empty, and the foam mold is replaced by EPC, which will lead to the filling time of EPC longer than that of sand casting. The reason is that the existence of foam pattern will react with molten metal. Moreover, this process belongs to endothermic process, which will lead to the decrease of the temperature of molten metal and the decrease of the fluidity of molten metal. In addition, the product of reaction between foam pattern and molten metal is gas, which is equivalent to a certain resistance to the flow of molten metal, which will also decrease the fluidity of molten metal.
2) The original process adopts the bottom pouring system. Through the simulation analysis of the mold filling process of the original process, it is found that the maximum shrinkage cavity of the box is located at the thick part at the bottom of the box, but the original process does not place the position of the inner gate here. Moreover, there are many shrinkage and shrinkage cavities in the upper half of the box. This is because the metal liquid of the original bottom injection gating system is from bottom to top. When the metal liquid reaches the upper half of the box, the temperature has decreased, resulting in poor fluidity of the metal liquid and easy to produce shrinkage and shrinkage casting defects.
4) Through the simulation analysis of the original process and comparing the casting defects produced in the actual production with the casting defects produced in the simulation, it is found that the two are basically consistent, which verifies the accuracy of the simulation results and shows that the setting of the simulation process parameters is also reasonable.
5) Observe and analyze the simulation results, improve the original process of the gearbox box, and design a new gating system. The new gating system is stepped. Two inner gates are set at the thick part at the bottom of the box, hoping to supplement the thick part of the ground and reduce the maximum shrinkage rate; An inner gate is set on both sides of the upper half of the box, hoping to reduce the casting defects of shrinkage porosity and shrinkage cavity in the upper part of the box.
6) The solidification process of the new process is simulated and analyzed. It is found that the maximum shrinkage rate and the total amount of shrinkage porosity are reduced. In order to further reduce the casting defects of shrinkage porosity and shrinkage cavity, the new process was optimized. The optimized process is used for simulation, and the simulation results are improved compared with the new process.