METHOD FOR FORMING THIN-SHEET DUAL-CURVATURE PARTS BY STRETCHING Russian patent published in 1995 - IPC

FIELD: plastic working of metals. SUBSTANCE: method involves stretching thin-sheet billet at preliminary forming stage over punch with inserts positioned on punch and adapted for increasing curvature of sloping portions of parts; determining curvature of inserts by design dependence; effectuating preliminary stretching of billet till lengthening deformation in accordance with predetermined geometrical part configuration is provided; conducting thermal treatment and final forming by stretching billet over punch without inserts, with punch having shape of final part. As a result formation of wrinkles is prevented. EFFECT: improved quality of parts by absence of wavy sloping portions. 2 dwg