METHOD OF MAKING RETURN BENDS FROM HIGH-ALLOY STEEL Russian patent published in 2012 - IPC B21D9/08 

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming, particularly, to making return bends from high-alloy steel. First thick-wall tube is bored out and ground to surface finish Ra=0.2…04 mcm. Then, it is cut to developed length of return bend increased of machining and sealing allowance. Then, plugs are welded to faces of branch pipe thus made to force inert gas, e.g. argon, therein. Produced blank is heated in furnace to hot deformation temperature and bent in die at press. Thereafter, it is cooled down and thermally treated to cut aforesaid plugs. Now, it is machined and subjected to hydraulic tests.

EFFECT: higher quality of return bend.

2 cl