METHOD FOR COLD PILGER ROLLING OF TUBES Russian patent published in 2000 - IPC

FIELD: rolled tube production, namely, manufacture of tubes from hard-to-form titanium alloys by cold lengthwise rolling in roll grooved pass. SUBSTANCE: method comprises steps of performing before rolling process cold drifting of blank inner diameter by value consisting (1.5-3.0) of elastic deformation value until occurring residual deformation; sizing wall with absolute reduction value of wall equal to (0.1-0.25)(1-dt/d3)t3; reducing tube by wall and diameter along portion of drift having conicity degree 2tgα_o=0.007-0.013; in addition realizing free reduction of tube by diameter, reducing wall at sizing tube and performing free reduction of tube by diameter on transition portion. In order to realize it, multicone drift is used. Said drift has next relation between total length of portions for reducing tube by diameter and length of tube portions reduced by wall and diameter: lred dr/lred t = (0.3-0.7) δ_in.p.•lnμt/δ_in.b.•lnμd, where δ_in.p.,δ_in.b. - yield strength values of metal of ready tube and blank; μt,μd - elongation values of tube reduced by wall and diameter; t_b,d_b,d_t - wall thickness value of blank, diameters of blank and tube respectively. EFFECT: enhanced accuracy of geometry of tubes made of hard-to-form alloys such as titanium alloys. 1 dwg, 1 ex