METHOD OF ROTARY DRAWING OF THIN-WALL SHELLS WITH BULGES Russian patent published in 2012 - IPC B21D22/16 

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming. Proposed method comprises fitting tubular billet onto mandrel and acting thereon by deforming rollers in two or several passes. Tubular billet shaping is performed on main and adjacent sections, on sections with outer and inner buldges and on sections of deforming rollers engagement and disengagement. Said rollers are displaced on engagement sections along convex/concave circle arc paths and, on disengagement sections, along concave/convex circle arcs. Angle of tangent inclination to circle arcs in inflection zone is set equal to 5-30°. Shaping on sections of tubular billet joint is performed to radius making at least one thickness of tubular billet wall. Shaping of tubular billet inner buldges is carried out by rollers with working surface profile composed of conical and cylindrical sections. Length of cylindrical section and radius of toroidal sections make 0.2-0.4 and 0.4-0.8 of tubular biller thickness, respectively. Clearances between tubular billet inner surface and mandrel in shaping outer and inner buldges are set equal to (0.01÷0.1)t₀ and (0.15÷0.5)t₀, where t_0(mm) is tubular billet wall thickness.

EFFECT: high-quality surface, high precision of sizes and factor of metal utilisation.

7 cl, 6 dwg, 1 tbl, 3 ex