METHOD FOR SHAPING DOUBLE-CURVATURE SHEET PARTS Russian patent published in 2002 - IPC

FIELD: plastic metal working, namely manufacture of members of envelopes welded in dies at successive local pressing down. SUBSTANCE: method comprises steps of successive local pressing down at relative motion of blank and shaping tool; moving blank with predetermined pitch in such a way that to partially overlap each previous spot of acting of shaping tool upon blank; achieving values of maximally possible stretching deformation at which mechanical properties of blank material are sustained or achieving cross and longitudinal predetermined curvature radius values, by several working stages while uniformly distributing said values to above mentioned several stages; passing from one stage of blank shaping to another at providing value of stretching deformation no more than 2% for steel blanks and no more than 1% for blanks of light alloys; overlapping each previous spot of punch action upon blank by value no less than half of its diameter. Such method provides uniform distribution of deformation along blank surface area and allows to decrease factors mostly influencing upon material properties such as stretching deformation value and material thinning degree. Decreased dangerous stretching deformation values allow to eliminate heat treatment after shaping for recovering metal properties. EFFECT: reduced cost of simplified process for making double-curvature sheet blanks. 2 cl, 1 dwg