Study On The Steel-Aluminum Clinch-Adhesive Connection Process Based On Inclined Wall Die

With the development of automobile industry,whether for the traditional fuel vehicles or new energy vehicles,the lightweight design of the body is the focus of research.Improving the lightweight design of the body can not only improve the fuel utilization rate,but also improve the endurance of new energy vehicles.At the same time,in order to take into account the safety of automobile body,multi-material body structure become the mainstream.Different materials bring about the connection problem of body structure.As a environment-friendly connection technology,clinch achieves the connection of different parts through the plastic deformation of the plates without additional rivets and heat input,it provides a new idea for solving the connection problem of steel sheet and aluminum alloy sheet.But at present,the connection strength of joints can not meet the requirements of use.In order to solve this problem,the inclined wall die is proposed based on the traditional clinch die,and clinching process is combined with the bonding process to improve the connection quality,the main research of this study is as followings:(1)Taking 5052 aluminum alloy sheet and Q235 steel sheet as the research objects,the traditional forming process of clinching was simulated,and the inclined wall die was designed based on the deformation and flow characteristics of the sheets during the forming process.Compared with the traditional clinching process,clinch with the inclined wall die can greatly improve the joint interlock and keep the neck thickness unchanged.And the mechanism of the inclined wall die in the process of clinching was obtained through the finite element simulation.(2)Combining the clinching process based on inclined wall die with the bonding process,two kinds of clinch-adhesive connection process schemes,full gluing and local gluing,were designed.Then,according to the characteristics of the inclined wall die,the inclined wall clinching die was designed and manufactured.Based on the die,clinch connection test?full-adhesive clinching test and local-adhesive clinching test of steel sheet and aluminum alloy sheet were carried out.The effectiveness of the clinching finite element model and the adhesive-clinch finite element model based on the inclined wall die were verified by experiments.By comparing the mechanical properties and finite element simulation results of the joints of each scheme,the local-adhesive clinching connection process scheme was selected.(3)The local-adhesive clinching connection process scheme based on inclined wall die was further optimized.The neck thickness and interlock of the joint were taken as the evaluation index.The key process parameters affecting the quality of the joint and the corresponding parameter range were determined by the sensitivity analysis of the parameters,including the process parameter: the bottom thickness;the structural parameters of the inclined wall die: the punch radius,the punch side angle,the punch fillet,the depth of the die,the groove fillet,the inclined wall angle.Then,the Kriging model of key parameters of the clinch-adhesive connection process and the neck thickness? interlock of the joint was established.Based on the model,70 groups of Pareto front optimal solution sets are obtained by multi-objective genetic algorithm optimization.Finally,the optimal combination of local-adhesive clinching process parameters of inclined wall die was selected.