Study On The Design Of Cooling Channels And Heat Transfer Effect Of High Strength Steel Hot Forming Mould

With the rapid development of the automobile industry,the cost,safety performance and lightweight of the automobile have been paid great attention.High strength steel has been widely used in the field of auto parts to improve the performance of automobile.Because of the high yield strength and tensile strength of high strength steel,the stiffness of the car is greatly improved.The increase of strength can reduce the use of the stiffeners on the body.The weight of the body and the number of welding points of the welded reinforcement are decreased effectively so as to save the cost.Most automotive parts are stamping forming,but high strength steel can't meet the requirement by ordinary cold stamping.Therefore,hot stamping is required to produce related automotive components.In this paper,the automobile upper beam produced by hot forming named 22MnB5 high-strength steel is taken as the research object.The cooling system of the hot forming mold and the temperature change of the sheet during stamping are studied.The main tasks are as follows:A new method is proposed to uniform the flow rate of the thermoforming cooling system to ensure that the cooling of the plate is uniform.The concrete method is to offset connecting pipes of main channel to control the flow rate of surface pipes and select the best optimization parameters by orthogonal test.Fluent is used to analyze the flow rate of the cooling system before and after optimization,and the corresponding cooling system experimental platform is set up.The results of simulation and experiment are compared to verify the feasibility of the method.The flow and solid heat coupling analysis of the model before and after the optimization was carried out to observe the temperature distribution of the sheet material before and after the velocity homogenization.The hot stamping forming experiment of the upper beam parts of a high strength steel was carried out.The velocity and pressure of the import and export are detected,and the temperature of the plate is collected by the infrared temperature camera.After the experiment,the temperature distribution of the sheet is obtained,which provides the initial condition and the comparison of the results for the simulation.The hot stamping forming and heat transfer process of the upper beam are analyzed by using LS-DYNA and Fluent.The material parameters of 22MnB5 and the boundary conditions in stamping process are set up,and the temperature of each part after stamping is obtained after simulation,then compare analyzed results with the experimental results.From the result,we can see that the coincidence between simulation and experiment is high,so we can see that the boundary conditions and material parameters in the simulation are set up more accurately,and the finite element analysis plays a certain role in the forming process of hot stamping.