An approach to predict blank shape for auto-position in multistage sheet metal forming

The stamping parts are often formed through several stages such as drawing, trimming, flanging and sizing. The relative position between tool and blank has a great influence on the multistage sheet metal forming simulation, especially for avoiding initial penetration which may lead to failure of simulation. In multistage simulation, tool position depends on the blank shape formed by the prior stage, so it may cause difficulty in setting up the simulation without blank shape in the latter stages. An approach to predict the blank shape is proposed for multistage sheet metal forming simulation. In order to obtain an approximate blank shape, initial blank mesh is projected to the die mesh first, and then smoothed by sliding constraint surface. The method has been proved to be very useful in solving position problem in multistage simulation of a body side.