PRODUCTION OF SEAMLESS HOT-ROLLED PIPES AT PRU WITH PILGER MILL Russian patent published in 2014 - IPC B21B19/04 

FIELD: metallurgy.

SUBSTANCE: proposed method comprises heating the ingots to ductility temperature and piercing them at helical rolling mill to sleeves with different rolling-out µ_pr, µ_pr1 and µ_pr2 over the length. Ingots are pierced at helical rolling mill to sleeves shaped to two hollow connected truncated cones. One of the latter features length equal to (0.10-0.15) of sleeve length, its smaller base being located at front end along sleeve piercing. Second cone features length equal to (0.85-0.9) of sleeve length, its smaller base being located at rear end along sleeve piercing. Sleeves of i^th size are rolled at Pilger mill to pipes of j^th size at constant amount of advance m_ij, steady rolling and rolling-outs µ_pg1ij, µ_pg2ij, and µ_pg3ij, respectively, at seeding, steady rolling and end of rolling - at withdrawing of Pilger heads from the sleeve conical ends. Pipe lengths are cut to pipe arms, process wastes, that is Pilger heads, and seed ends are cut off by hot-cutting saw.

EFFECT: lower metal input, higher precision, higher efficiency, ruled out sleeve rear end collapse.

3 cl, 1 tbl