HOT-ROLLED TUBE MANUFACTURING METHOD Russian patent published in 2015 - IPC B21B17/04 

FIELD: metallurgy.

SUBSTANCE: method involves piercing of a billet, tube rolling in two in-series located mills for longitudinal rolling in rolls with many-sided grooves with a number of sides that exceeds six and with height of the groove of the first mill, which is bigger than that of the groove of the second mill by 1-2 mm, on short mandrels, with outer diameters equal to outer diameter of the mandrel of the first mill or outer diameter of the mandrel of the second mill is by 1-2 mm smaller than outer diameter of the mandrel of the first mill with first mill drawing µ=1.1-1.5 and µ=1.05-1.15 in the second mill, tube grooving is performed with drawing µ=1.1-1.3 in a sizing mill with the groove diameter in the last stand of 114.0-117.0 mm.

EFFECT: possibility of manufacturing tubes with reduction of defects along a longitudinal rolling mark on the tube inner surface.

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