Study On Structure Optimization Of Die Casting Mold For A Complicated Shell Part Based On Numerical Simulation

In this paper,the rationality of die structure is studied by means of numerical simulation,and the reason of thermal crack in die castings is analyzed and the method of eliminating thermal crack is proposed.A complex shell mold is analyzed by Pro CAST software,and the numerical simulation results of thermal cycles and mold filling show that the gating system and overflow system are reasonable.The mold temperature field simulation results analyze the hot areas in the mold cavity surface,and the temperature gradient in the region is reasonable,which reflects that the internal cooling channel arrangement is suitable for adjusting mold temperature.The temperature measurements in casting process are in good agreement with the simulated values,so the simulated temperature results are reliable.Based on the temperature field of the mold in thermal equilibrium state,the numerical simulation of stress field was carried out.The local strain method was applied to estimate the die life according to the maximum stress on the cavity surface.Further,completing the simulation of mold filling and solidification process for a hot-crack casting.The simulation results of flow field,temperature field and stress field were comprehensively analyzed,and it was found that the stress model of the hot-crack region was a typical one-dimensional model.Therefore,this paper analyzed thermal crack based on the strength theory and feeding solidification theory.In this paper,it is believed that the cracked metal film of molten metal which is failed to be fed at the initial stage of solidification may cause the thermal crack,so the casting surface appeared shallow crack after complete solidification.Or the thermal stress caused by too large temperature gradient exceeded the tensile strength limit results in the thermal crack.In order to eliminate the thermal crack,two schemes of improving the gating system and the cooling system were proposed,and the simulation results showed that the thermal crack region after the improvement of the gating system could be fed well and get an even temperature field,which greatly reducing the probability of thermal crack.Finally,the real production shows that the scheme of improving the casting system can effectively prevent thermal crack and ensure casting quality.