PRODUCTION OF SEAMLESS HOT-ROLLED CASING PIPES AT PRU WITH PILGER MILLS FOR THREAD CUTTING Russian patent published in 2015 - IPC B21B21/00 

FIELD: process engineering.

SUBSTANCE: invention relates to pipe rolling. Proposed method comprises placing the ingots or continuously cast billets to continuous furnace and heating them to ductility temperature, piercing said ingots and billets to sleeves, rolling said sleeves to pipe units at fixed feed of sleeves to the source of deformation at stable rolling processes, and cutting said pipe units to multiple length pipes. Amount of feed of pipe units over their length is intermittently varies (2n+1) times where n is the number of pipe lengths, pieces. Seeding at rolling of the latter over the length of 1000-1200 mm is executed with feed of sleeves to the source of strain m_{j s}=(0.5-0.6)m_{j st}, where m_{j st} is fixed amount of sleeve feed to the source of strain at stable j^th size pipe rolling conditions with the feed of sleeves m_{j st} being performed at pipe length equal to 10250±250 mm, feed at transition sections of pipe lengths is performed over the length of 1800-2000 mm and decreased to m_{j F}=(0.6-0.7) m_{j st}, while remaining part of the sleeve is rolled with the feed to the source of strain m_{j F.S}=(0.55-0.65)m_{j st}.

EFFECT: higher reliability of thread joints, lower metal input.

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