METHOD FOR MAKING HOLLOW ARTICLES WITH VARIABLE THICKNESS OF THEIR WALLS Russian patent published in 2001 - IPC

FIELD: plastic metal working, namely manufacture of products with variable-thickness walls. SUBSTANCE: method comprises steps of drawing and necking wall of blank along predetermined portion of blank length and expanding blank. At expansion on outer surface of blank in zone of transition from small thickness to large thickness forming profile having cone portion and toroidal portion with radius exceeding curvature radius of free bending of blank cross section. Method also comprises operation of sizing-drawing with use of die having toroidal working profile with radius more than curvature radius of free bending of blank section but less than radius of toroidal portion on outer surface of blank after expansion. EFFECT: enhanced accuracy of outer diameter of article, lowered labor consumption, reduced metal consumption. 5 dwg