Research On Hot Forming Process Parameters And Springback Control Of Ultra High Strength Steel With Central Channel

The central channel is an indispensable part of the automobile body parts.There are many parts arranged here.The structure is varied and the shape is irregular.It is the largest part of the current automobile hot forming parts,and it is also an important structure on the car floor.Because of its larger size and complex shape,there is a problem of low strength of rebound and edge pressing.These defects will seriously affect the quality of the parts until the assembly of the subsequent parts.Therefore,before the parts are put into production,numerical simulation technology is needed to effectively predict parts defects.Taking the central channel produced by a mold company as the research object,this paper uses the Dynaform software to analyze the forming limit diagram of the central channel and the possible quality defects such as springback and thinning.The influence of the distribution of the cooling water velocity in the mold on the quality of the parts can be analyzed by using the Fluent software,and the suggestions for modification are put forward.Finally,the response surface methodology is used to optimize the molding process parameters and provide guidance for the company's parts production,so as to produce the products that meet the requirements.Based on the above contents,the following aspects are mainly studied:First of all,a simple analysis of the central channel is carried out to understand the structural characteristics of the central channel and the region that may be deformed,and then the hot stamping process scheme of the central channel is determined.This paper analyzes the mechanism of springback and the factors that influence springback,and lays the foundation for further finite element analysis and parameter optimization.Secondly,based on the simulation of the thermoforming process based on Dynaform software,the forming limit diagram of the central channel,the change of the thinning rate of the sheet thickness and the change of the rebound amount are emphatically analyzed.The parameters of the central channel thermoforming process are studied:the influence of the edge force,the holding time,the heating temperature and the friction coefficient on the springback,so as to obtain the optimum range of the simulation value for each process parameter.By using the response surface method,a new target function and two order response regression model are set up,and the Design-Export software is used to further analyze the regression equation,so as to get a group of optimal combination of the central channel thermoforming process parameters.Finally,based on the Fluent software,the flow velocity of cooling water in the cooling system is analyzed,and the influence of the cooling water velocity unevenness on the forming quality is studied,and the improved method is put forward.The results show that when the other conditions are fixed,the best range of parameters is obtained.In the actual production process,the above conclusions can be used to set up the technological parameters better and control the springback effectively.By optimizing the parameters by the response surface method,a set of optimal combination parameters can be obtained:the heating temperature is 948.21 C,the pressing force is 60KN,the friction coefficient is 0.40,and the holding time is 11S.After optimization parameters are adjusted,the numerical simulation results show that the maximum resilience of the central channel decreases.