METHOD FOR FORMING BOTTOMS OF FLAT BLANK Russian patent published in 2001 - IPC

FIELD: plastic metal working, possibly sheet forming. SUBSTANCE: method for forming bottoms comprises first and second drawing operations; preliminarily determining type and path of deformations of blank at first drawing operation and value of ductility factor of blank material after termination of second drawing operation; according to results of previous step determining percentage ratio ofdepth values of first and second drawing operations; at end of slide stroke forming annular rib in central part of blank at first drawing whose depth is less than depth of second drawing and forming technological ribs with discrete pitch on radius portion of lateral wall of bottom; at second drawing restricting displacement of material of annular rib in central portion of blank towards its center. It allows to make vehicle body parts having large ductility factor of material due to changing type and direction of deformations at first step of forming. EFFECT: enhanced quality of formed bottoms. 8 cl, 2 dwg, 1 ex