METHOD OF MAKING HOLLOW METALLIC TANKS Russian patent published in 1997 - IPC

FIELD: production of hollow thin-wall articles from high strength, difficult-to-form steels and alloys. SUBSTANCE: method comprises steps of non-uniformly heating flange portion of blank in radial direction up to temperature of hot deforming and stage-by-stage drawing of said blank; at first drawing operation making semifinished product whose height consists at least 1.2-1.5 of its diameter without thinning initial material and deforming at rate of 20-40 mm/s; performing second and further drawing operations at thinning wall at least by 18-20% and at rate of 20-60 mm/s; during all drawing operations sustaining temperature in zone of part cutting equal at least to 0.8 of upper limit of temperature range of hot deforming of material to be formed; reducing necking portion after drawing operations at rate 4-7 mm/s. EFFECT: enhanced quality of articles, their increased capacity, enlarged manufacturing possibilities, lowered cost price due to realization of optimal temperature rate modes of deforming in combination with first drawing operation without thinning and second drawing operation at predetermined thinning of walls. 4 cl, 11 dwg, 2 tbl