Simulation Of Cooling Process Of Hot Stamping Die

Hot stamping technology is one of the central issue in the field of high temperature metal forming in recent years.For complex shaped parts,the internal water channel of hot stamping die is complex,whether the waterway structure is reasonable,the flow velocity distribution is uniform,and the cooling effect is ideal can't be Judged by experience.The numerical simulation method can be used to simulate and predict the production process,avoid design defects,optimize process parameters,and improve production efficiency.The design of the hot forming tool cooling system is a key technology for hot forming,which directly determines product quality and production efficiency.The hot forming die's cooling involves the fields of material phase change,heat transfer,fluid mechanics,stamping and other fields.It covers a wide range and various parameters.The systematic analysis of the influence of various key factors on the cooling effect of hot stamping die can provide the necessary theoretical support for the design and optimization of hot stamping die.The water temperature,the specific heat capacity of the mold,the thermal conductivity,the heat transfer coefficient between the mold and water,the heat transfer coefficient with the maximum contact pressure between the mold and the sheet,the holding pressure and other factors of the stamping die cooling system are analyzed under the continuous production conditions.Among them,The most important factor affecting the cooling effect is the water temperature.With the increase of the water temperature,the die temperature of the forming parts increases linearly.Heat transfer coefficient between die and water,heat transfer coefficient between die and sheet metal and heat conductivity of die also have great influence on cooling effect of cooling system of hot stamping die.With the increase of heat transfer coefficient between die and water,heat transfer coefficient between die and sheet metal and heat conductivity of die,the temperature of the fifteenth punch forming part decreases gradually,but all of them have a critical value.When the critical value is exceeded,the cooling effect of the die cooling system will not change significantly.The holding pressure and specific heat capacity of die has little effect on the cooling effect of the hot stamping die cooling system.AutoForm and CFX are used to simulate the cooling effect of hot stamping dies considering the change of heat transfer coefficient between dies and forming parts due to contact pressure,gap between dies and sheets caused by drawing thinning,cooling shrinkage of forming parts and volume expansion and latent heat release caused by phase change.The existing laws of cooling system of hot stamping die in continuous production process are analyzed in detail.The temperature of forming parts,die surface temperature,water flow velocity and temperature distribution were obtained.The simulation results show that most of the hot spots are located in the corner position and parts thinning area.Because the contact pressure between the forming part and the corner convex surface is large and heat transfer is good,while the contact pressure between the forming part and the corner convex surface is small or even there is gap,heat transfer is poor,most of the heat is transferred through theconvex position of the die.Finally,hot spots are formed at the convex corners of the forming parts and dies.Temperature field of die and sheet metal in continuous production process was obtained by infrared thermal imager,and compared with simulation results.The temperature field distribution is inaccurate except that the temperature prediction is inaccurate due to severe die wear,and the temperature difference in other 90% areas of the forming parts is within 10 ?.