Prediction of Blank Holder Force in Stamping Using Finite Element Analysis

摘要

Introduction of multiple point cushion technology in stamping press has provided an additional degree of freedom to improve the formability of the materials by changing the blank holder/binder/cushion force in space/location and in stroke during the process.However,this advanced capacity of die cushion is being underutilized in production because it is difficult to estimate the force required in each pin and its variation throughout the press stroke to form a part with desired quality.This paper describes two methods namely,a)Numerical Optimization,b)Adaptive simulation coupled with finite element analysis of the stamping process to predict constant and variable binder force(variation in stroke)to form the part without failure and with reduced springback.The blank holder force is predicted by detection of a)wrinkles,b)thinning and c)stress variation through thickness direction during the FE simulation to eliminate potential defects such as wrinkles and thinning and reduce springback in the part.The developed technique was applied to two parts namely a)IFU Hishida die,and b)Numisheet S-Rail to predict blank holder force to minimize thinning and springback respectively.