| 摘要 |
FIELD: production of ingot-blanks by electroslag refining of hard-form steels and alloys, rolling commercial tubes of large and mean diameters in tube rolling plants with pilger mill and conversion tubes for further rerolling in tube cold rolling mills. ^ SUBSTANCE: method comprises steps of casting ingots with size 420 -620 x 1750± 50 mm by electroslag refining; mechanically working - turning them to ingot-blanks with size 400 -600 x 1750 ± 50 mm; heating till yielding temperature of ingot-blanks and expanding in radial forging machines to sleeve-blanks for further turning and boring till removing forging flaws; boring inner diameter of ingot-blanks to sleeve-blanks with inner diameter exceeding diameter of drift by 30 - 35 mm; heating ingot-blanks and sleeve-blanks till yielding temperature; piercing ingot-blanks with diameter 400 - 500 mm in skew rolling mill to sleeves; rolling sleeves; rolling expanded and turned sleeve-blanks in pilger mill with use of backing carbonaceous rings to commercial or conversion tubes with diameter 219 - 426 mm; performing first piercing of ingot-blanks with diameter 540 - 600 mm to sleeves on mandrel with diameter 250 - 275 mm; again heating sleeves from hot or cold fit till yielding temperature; secondary piercing-rolling out of them in skew rolling mill on mandrel with diameter exceeding that of drift by 20 - 25 mm; rolling sleeves to commercial or conversion tubes with diameter 351 - 450 mm in pilger mill with backing carbonaceous rings. Ingots cast by electroslag refining are hollow ones, they have relation of diameter to wall thickness D/S = K1 and height H = K2*D where D - outer diameter of hollow ingot of electroslag refining, mm; S - wall thickness of hollow ingot of electroslag refining, mm; H = 2500 - 3000 - height of hollow ingot of electroslag refining, mm; K1 = (4.0 -6.0) -coefficient whose larger values correspond to hollow ingots of larger diameters; K2 = (4.0 - 7.0) -coefficient whose larger values correspond to hollow ingots of less diameters. Hollow ingots of electroslag refining are bored and turned to sleeve-blanks till removing flux and casting-origin flaws with inner surface roughness Rz < 40 micrometers and outer surface roughness Rz < 60 micrometers. Hollow ingot-blanks are heated till yielding temperature and rolled in pilger mill to commercial tubes with diameter 219 - 426 mm and elongation value mu< 6.0 and to conversion tubes with diameter 273 - 450 mm and elongation value mu <4.0. ^ EFFECT: lowered consumption of high-cost metals of hard-to-form steels and alloys, reduced cost of hollow ingot-blanks in comparison with expanded sleeve-blanks, decreased cost of commercial and conversion tubes of given assortment. ^ 3 cl, 1 tbl |
