METHOD OF MAKING LAMINATE TUBES Russian patent published in 1994 - IPC

FIELD: metal pressure forming. SUBSTANCE: method comprises steps of coaxial assembling of tube layer of different diameters and their drawing; using as different layers straight-seam tubular blanks, produced by laser welding with seam width, equal to kεh, where k=0.3 - 1.1; h - tube wall thickness; subjecting an inner layer before assembling operation to drawing with deformation degree 40-90 %; using it in cold-hardened state; joining the layers successively, performing a drawing operation with elimination of clearances between the layers; determining deformation degree of each layer according to an expression, given in a description of the invention. EFFECT: higher efficiency. 1 cl, 2 tbl