METHOD OF FORMING PARTS OF MOULDED-WELDED SHELLS OF SPHERICAL AND ELLIPTICAL SHAPE Russian patent published in 2012 - IPC B21D11/20 

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming. Proposed method consists in consecutive local clampings in several passes. In first pass, spherical surface is produced with curvature radius equal to maximum preset radius on entire surface of sheet billet. Here, used is round female die and spherical male die. In second pass, sheet billet section with smaller curvature radius is drawn using annular female die and spherical made die. Working radius of said male die varies with drawing radius, with due allowance for spring back of billet and its thickness and depends upon Gauss curvature of part surface: Note here that where R_d is drawing radius, m; R₁ is preset transverse radius of billet central surface, m; R_{2 -} is preset lengthwise radius of sheet billet central surface, m; K is double Gauss curvature of billet central surface, 1/m². In third pass, spherical make die is used with working surface radius proportional to preset transverse radius R₁ with due allowance for spring back and thickness, as well and prismatic female die.

EFFECT: reduced residual strain and thinning.

2 cl, 2 dwg