Numerical Simulation And Parameter Optimization Of Cooling System Of 22MnB5 Ultra-high Strength Steel Hot Stamping Die

The most direct way to realize the lightweight of automobiles is to use less materials to meet the performance requirements of the original automobile parts,and ultra-highstrength steel is the material that meets the lightweight of automobiles.However,due to the poor stamping effect of ultra-high-strength steel at room temperature and excessive springback after forming,hot stamping technology is required for production.Since the cooling rate of the ultra-high-strength steel forming parts during pressure quenching only exceeds 27?/s,the internal structure of the forming parts can be completely transformed into martensite,thereby greatly improving the performance of the forming parts.Therefore,the ultra-high-strength steel hot stamping forming die is the key to the hot stamping technology.The research work of this paper provides a design basis for the development of the ultra-high strength steel hot stamping forming die system.Using the optimized die cooling system parameter combination,an improved ultra-high strength steel hot stamping forming process parameter combination is obtained.It provides an important reference for the selection and determination of the actual ultra-high-strength steel hot stamping process parameters.In this paper,the key parts of the door reinforcement of a certain model are used as the basis for the design of the ultra-high-strength steel hot stamping die,and the numerical simulation technology is used to systematically analyze the cooling process of the hot stamping die.The main contents of the research are:(1)The basic principles of heat transfer and fluid mechanics involved in the cooling process of hot forming are analyzed,and the formula for calculating the area of cooling pipe required for the cooling system is obtained by deriving the existing formula.(2)On the basis of theoretical analysis,the geometric model of hot stamping die for key parts of ultra-high-strength steel door reinforcement is established by using 3D modeling tools,and its cooling system is preliminarily designed.(3)Using the orthogonal experimental design method,nine groups of ultra-highstrength steel hot stamping forming die systems with different parameters were obtained,and the nine groups of models were numerically simulated in the cooling process in FLUENT.Through the orthogonal analysis,the optimal parameter combination of the ultrahigh strength steel hot stamping die system is obtained as follows: the diameter of the cooling pipe is D=6mm,the distance between the pipes is S=13mm,and the distance from the top of the pipe to the profile surface is H=8mm.The structural strength of the optimal mold system is analyzed,and the results show that the structural strength of the mold meets the safety performance requirements under the holding pressure of 15 MPa.(4)The influence of various process parameters on the cooling effect in the cooling process of ultra-high-strength steel hot stamping is simulated and analyzed,and the process parameters are improved based on the simulation results and actual production conditions.The improved process parameters are combined as follows: the pressure holding cooling time is 10 s,the mold air cooling time is 3s,the cooling water flow speed is 3m/s,and the cooling water flow temperature is 20?.