| Aluminum alloy is the most widely used light alloy in automobile body.Compared with other connection technologies,Self-Piercing Riveting(SPR)can realize the connection of aluminum alloy sheets more efficiently.The quality of single SPR joint is affected by the parameters of rivet and die.However,in the current analysis of rivet and die,there are still some problems,such as insufficient consideration of the comprehensive influence of parameters and insufficient research on type selection.In this paper,taking the aluminum alloy body plates of a passenger car as the research object,a joint optimization scheme of multiple key parameters of rivets and dies is proposed,and based on this,the matching relationship between rivet,die and body plates is studied,which improves the quality of SPR joints and guides the selection of rivets and dies for riveted body parts.It has important research significance and practical application value.Firstly,the characteristics of SPR are briefly summarized,and the geometric dimension and tensile-shear resistance of riveted joint after forming are analyzed.The simulation model of SPR based on ALE method was established to study the aluminum alloy sheets commonly used in automobile body.The geometric dimensions of the formed joints were obtained.Then compared with the riveting experiment results,the errors were all within the engineering limitation,so the validity of the model was verified.Then,the tensile-shear strength of the formed joints was analyzed by combining simulation with experiment.Secondly,the parameters of rivet and die are optimized jointly.Five parameters,such as the length of rivet,the radius of die,are taken as the main factors affecting the forming quality of the joint.Through sensitivity analysis test,the influence trend of each parameter on the geometric size of the formed joint was obtained to determine the optimum range of the parameters.In the CCD test,the geometric size of the formed joint was taken as the system response,and the response surface model was constructed based on the test results.Then the multi-objective optimization model based on AMGA algorithm was constructed to solve the problem.The results show that the optimized combination of rivet and die increases the undercut by 10%,the bottom thickness by 8.6% and the remaining thickness by 3.1%.By comparing the tensile-shear strength of the joints before and after optimization,it can be seen that the tensile-shear strength of the joints after optimization has increased by 4.9%,which proves the feasibility of the optimization scheme.Finally,the matching relationship among rivet,die and body plates is studied.Four kinds of aluminum alloy plates with different thickness were selected.The influence of the placement order of aluminum sheets on joint forming quality was analyzed by experiment.The matching test of plate thickness was designed to obtain the parameters of rivet and die with reliable forming quality under different plate thickness combinations.The parameters obtained were fitted by MATLAB software,and the mathematical model of matching rivet and die based on aluminum alloy plate thickness was constructed.The applicability of the matching model is verified,which promotes the rapid application of SPR in the connection of aluminum alloy body plates. |
PDF Full Text Request