Abstract: Based on the hole-expanding forming theory in plastic mechanics, applying the layered idea, a layer-by-layer- reverse-planishing blank shape estimation approach is proposed for the complex cover panels with free form surface so that the blank shape estimation can be executed effectively. The present approach considers synthetically the influence of material mec- hanical properties, work-hardening effect and plastic defor- mation during cover panels forming on blank shape. Simult- aneously, the base-surface idea of the section curve length dev- elopment approach is adopted in order to determine the initial blank contour shape and position. Furthermore, by applying the continuity between adjacent layers during surface development- planish, this estimation approach develops a surface layer by layer according to the order of layering-planishing-expanding- re-layering. Therefore, it is expected to reduce effectively the amount of calculation and improve blank development effic- iency. Finally, by comparing the blank area, material utilization ratio, and stamping test results of the example’s development result with ones of the given traditional blank shape, the validity and reasonability of the proposed blank estimation approach are verified.

Key words: Blank shape estimation, Cover panels, Hole-xpanding forming, Stamping process