METHOD TO PRODUCT OIL-AND-GAS PIPE PREMIUM-TYPE THREADED JOINTS Russian patent published in 2010 - IPC B21B21/00 

FIELD: process engineering.

SUBSTANCE: invention relates to pipe rolling and can be used at pipe step-rolled mills. Proposed method comprises heating ingots in furnace, piercing ingots into barrels, rolling barrels to pipes at step-rolled mill, cutting pipes, heating, sizing or reducing and straightening. After straightening, pipe end shape is changed by centering the pipe by it OD, clamping it, heating strain zone and pipe end deforming. Rolling is performed along with reducing wall thickness by Δ=S1-S2, where S1 is pipe wall thickness without end shape change, S2 pipe wall thickness with end shape change. Strain zone is heated by circular inductor to 550-600°C. Pipe end is deformed by squeezing pipe through angle a relative to pipe outer surface. Strain zone length makes H=Δ/tgα. Pipe end is deformed by taper die representing a ring arranged on hydraulic cylinder plunger. Pipe end shape change does not affect pipe wall thickness.

EFFECT: reduced metal consumption, higher efficiency and lower costs.

7 cl, 1 tbl, 2 dwg