Global Sensitivity Analysis And Optimal Design For Wear Of Hot Forming Die

One of effective ways to realize automotive lightweight and improve collision safety is using hot forming parts of high strength steel on car body, with the improvement of sheet metal strength, cold stamping of high strength steel becomes more difficult. Sheet metal hot forming technology make use of the characteristic that blank plasticity enhances in high temperature, the combination of stamping process and heat treatment process solved the difficult problem of high strength steel stamping.But hot forming leads to some problems that the working condition of stamping mould is bad, the load is bigger, mould wear situation is more serious, the service life of mould and the quality of stamping parts are worse. At present, researches on hot forming mould wear are limited and mainly focus on the experimental researches,therefore, research on the hot forming mould wear has important practical significance.In this paper, thermal mechanical coupling model of hot forming was established, based on Archard wear model, the relationships between die wear distribution and temperature field and stress field was analyzed. And the relationships between die wear value and stamping speed, sheet metal temperature, cooling water temperature, mold temperature, friction coefficient, mould hardness are analyzed.Take hot forming mould of front column for example, based on the optimal Latin hypercube experimental design method and response surface modeling method, the Polynomial response surface approximation model between the wear volume and the stamping process parameters was established, and the sensitivity coefficients of stamping process parameters on wear volume was obtained by using global sensitivity analysis method. The results showed that sensitivity coefficients of stamping speed,sheet metal temperature, mold temperature were bigger, which have bigger influences on the amount of wear.On the basis of sensitivity coefficients calculation, the response surface approximation model between the wear volume and the stamping process parameters with larger sensitivity coefficient was established. The minimum amount of wear was the optimization goal, the stamping process parameters were optimized by using the multi-objective genetic algorithm, the best group of process parameters were searched in the given value space, which provided theoretical guidance for the design of process parameters in practical production.