Optimization and Modelling of Thinning and Geometric Accuracy in Incremental Sheet Forming Combined with Stretch Forming

Abstract

In the present experimental study incremental sheet forming is combined with stretch forming in order to obtain uniform thickness distribution, minimise thinning and to improve geometric accuracy of formed part. Preforming or stretch forming is initially done in order to obtain initial thickness distribution. Incremental sheet forming is then employed to obtain final part shape and thickness distribution. Forming time is also minimised considerably because of initial stretch forming process. The experiments are designed using central composite design (CCD) of response surface methodology. From the results, it is observed that preforming and preform tool shape have significant influence on sheet thinning. Also the combination of ISF and stretch forming processes yields in reduced thinning and uniform thickness distribution. Multi-performance optimisation using desirability function is also performed to improve thinning and geometric accuracy. Further mathematical models are developed which are in good agreement with the experimental results.