METHOD FOR PRODUCTION OF STEEL PIPES FROM LOW-ALLOYED HARDLY DEFORMED AND CARBON GRADES OF STEEL

摘要

FIELD: technological processes.;SUBSTANCE: invention is related to pipe-rolling, namely to production of steel pipes from low-alloyed hardly deformed and carbon grades of steel, and may be used in pipe rolling plants with a continuous rolling mill. Method includes heating of billets in furnace till temperature of 1190-1220°C, their broaching in screw rolling mill at water-cooled mandrel and longitudinal rolling in continuous rolling mill. Broaching of billets from low-alloyed hardly deformed grades of steel at water-cooled mandrel is done after broaching of 70-100 billets from carbon grades of steel without interruption and variations of machine time of broaching and broaching mill adjustments. Broaching is carried out with angles of roller feed β=9-11°, pressing upstream mandrel tip E_p=11-12%, reduction ratio µ= 1.7-2.0 and coefficient of deformation zone ovalisation ε=1.1-1.15.;EFFECT: improved quality of internal pipe surface concerning internal defects, increased resistance of mandrels and higher efficiency of broaching mill by reduction of its outage time for replacement of tools.;2 cl, 1 ex