METHOD FOR PRODUCING BENT TUBULAR BLANKS Russian patent published in 2007 - IPC B21D9/15 

FIELD: plastic working of metals, possibly manufacture of thin-wall bent pipelines.

SUBSTANCE: method comprises steps of placing blank in tube whose diameter exceed that of blank; filling gap between walls of blank and tube with water and then freezing blank and tube with fillers; performing common bending of tube and blank together with their fillers. Tube is made of such material and of such structure that provide its rigidity in radial direction and ductility in axial direction sufficient for preventing formation of corrugations and occurring of out-of-roundness at predetermined freezing temperature.

EFFECT: improved quality of tube blanks, enhanced efficiency of method.