| 摘要 |
FIELD: metallurgy. ^ SUBSTANCE: invention relates to production of 260-450ù40-70 mm-hot-rolled conversion pipes for subsequent tooling into high-quality pipes sized to 245ù19, 351ù36, 415ù50, 426ù40, 426ù50 and 436ù45 mm from antirust steel or for rolling at step-rolled mill of conversion 250-440ù30-60 mm-pipes with subsequent tooling for re-rolling at mills "Ñ" into pipes of aforesaid sizes. Proposed method comprises producing flat ingots by electroslag remelting, producing 1005.0 mm-diametre central bores in said ingots, heating them to plasticity temperature, piercing ingots at skew rolling mill into barrels, rolling of conversion pipes at step-rolled mill, cutting off step-rolled billets and seed ends by hot-cutting saw, pipe straightening, austenitisation, turning and boring to preset size with inner and outer surface roughness not exceeding Ra 10.0 mcm. Note here that conversion pipe rolling at step-rolled mill is performed for rerolling at "Ñ" mills. Conversion hot-rolled pipes are bored and turned at servo-drive machine tools into conversion pipes with metal removal defined by expressions öS"Æ.."=KöS"Æ..", öS".."=K1öS"..", where öS"Æ.." is metal removal amount in boring for rerolling, mm; öS"Æ.." is removed metal layer thickness in boring for finished size, mm; K=(0.5 - 0.6) is coefficient of metal layer thickness reduction with its larger magnitudes relate to large diametre pipes; öS".." is metal layer thickness in boring for temporary rerolling, mm; öS".." is removed metal layer thickness in boring for finished size, mm; K1=(0.4 - 0.5) is coefficient of metal layer thickness reduction with its larger magnitudes relate to large diametre pipes. ^ EFFECT: higher quality, reduced costs. ^ 4 cl, 1 tbl |
