METHOD OF FABRICATING THIN-WALLED PIPES Russian patent published in 2010 - IPC B21C1/24 

FIELD: mechanics.

SUBSTANCE: invention is intended for improvement of accuracy in dimensions of thin-walled pipes cross sections, mostly from corrosion-resistant steels, for instance for shells of fuel elements in nuclear reactors. Method includes pipe drawing in cone draw die on fixed cylindrical mandrel. Stability of pipes dimensions and reduction of elastic and thermal deformation are provided by the fact that at first pipe billet is rolled and drawn without mandrel, and afterwards drawing of pipe is carried out in fixed cylindrical mandrel, when drawing coefficient along section of pipe λ makes 1.25≤λ≤1.48, coefficient of drawing along pipe wall λ_s makes 0.90λ≤λ_s≤0.94λ, and after drawing on fixed cylindrical mandrel the billet is drawn again without mandrel through drawing die, diametre of calibrating part of which is accepted as equal to D_DR=D(0.998+0.0717logλ), where D - rated external diametre of finished pipe.

EFFECT: increased accuracy of precision pipes section dimensions.