Research On Design Method Of Hot Forming Die Cooling System For Variable Cross-section Parts

For the past several years,the electric vehicle industry,affected by policy,has enjoyed its fast and steady development and various auto companies has been setting their priority on such aspects as the increasement of range,safeguard device of batteries and passengers in collision.As a result,they have been attaching great importance to the weight aspect of automobiles and safety of the system in collision.In order to improve safety and lightweight tech on vehicles,a large number of well-known auto enterprises around the world has introduced hot stamping forming technology to produce body of cars and this technology has been increasingly used in assembly line.Expects who have been devoting themselves to this field are making their intensive research of it to deal with unavoidable problems that may occur in the process of manufacture.The thesis mainly combines simulation calculation and field experiment to study the temperature control and optimization design of cooling system on hot forming mould in continuous production.Related studies have been carried out as follows:In terms of the problem of uneven cooling of large and small ends in the hot forming process of common cross-section parts,a method of cooling system optimization is proposed,which is also called “conformal cooling system design with the change of mould surface”.For the inserts with different heating areas,this method aims to change the water pipe diameter,the number of water channels and the distance of the water channel from the profile of the cooling system in order to obtain similar cooling rates on inlays and uniform die surface temperature.What's more,Fluent and LS-DYNA were used to analyze the flow rate of cooling water before and after optimization and the distribution of mold surface temperature after multiple continuous stamping with an aim to verify the feasibility of the optimization scheme.The hot forming test was carried out on a thermoformed part of the top longitudinal beam.Then,the inlet and outleflo w rate,temperature and pressure were measured.Next,the infrared temperature camera was used to collect data on the temperature of the sheet after continuous stamping and the temperature on the die surface.Lastly,the temperature distribution of the she et and the die surface was obtained experimentally,and the initial boundary conditions and simulation results were compared with the hot forming simulation.The hot forming stamping and heat transfer process simulation analysis of the upper longitudinal beam hot forming parts was carried out.After the simulation,the temperature of each part of the stamped part and the die surface was obtained,and compared with the results in the experiment.Next,the optimized design of the part is carried out,and the distribution of cooling water flow rate and die surface temperature before and after optimization is simulated and calculated to solve the problem of uneven temperature cooling of the upper longitudinal beam part.It provides an optimization idea for common problems in the production process of B-pillar thermoformed parts,and proves that finite element simulation analysis plays a certain reference role in the forming process of hot forming.