Numerical Simulation Of Cooling System Of Hot Stamping Die

Hot forming process is a new technology for HSS(High Strength Steel) forming.Theprinciple of hot forming is that the ultra-high strength steel is heated to a certaintemperature in a few minutes,then the steel is formed and cooled rapidly in hot formingdie,the forming parts strength can be1500MPa,and the parts almost have nospring-back.By this technology,not only can we reduce automobile weight,but also makeautomotive parts have high strength which improves security.In hot forming coolingprocess,austenite transforms to martensite,and the forming parts become stronger withsmaller size martensite.This phase transition process is controlled by the cooling effect.Thehigher the cooling rate,the better the quality.Cooling effect includes cooling rate anduniformity,and it is closely related to the flowing of cooling system.Therefore,the coolingsystem of hot forming die is the core of the design of hot forming die.Researching on thecooling system of hot forming die can effectively optimize the design of hot forming dieand accelerate the development of the automobile industry.In this paper,the water flowing is simulated by Fluent at different channelshape,channel numbers and channel diameters.Then the paper discusses the water flowingin cooling cistern.The simulation results show that the U-shaped tube prevents the waterflowing.Reducing the number of channel and increasing the diameter of channel and cisternlength appropriately can inhibit the non-uniformity of cooling water flowing,but thevelocity of cooling water will be reduced, and there is a critical value of the length ofcistern,once exceeding the limit the cooling water is very uneven.The cistern width haslittle effect on the cooling system.This paper combines water flowing with heat transfer,and optimizes cooing channel parameters with orthogonal design.Among the simulation of hot forming at differentchannel diameters, channel boundary spacings and distances between channel top and diesurface,the paper studies water flowing and cooling rate.The simulation results show thatthe water tends to be uniform with the increasing of the diameter of channel.The waterflowing is uneven at large channel boundary spacings.Distance between channel top and diesurface influences the cooling rate most,the influence of channel diameter is less,and theinfluence of channel boundary spacings is least.The smaller the distance between channeltop and die surface, the higher the cooling rate.The best condition of cooling system is8mm of channel diameter,5mm of channel boundary spacing and3mm of distance betweenchannel top and die surface.