THIN-WALL TUBE BENDING METHOD Russian patent published in 2008 - IPC B21D9/15 

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

SUBSTANCE: method comprises step of placing hose of elastic material with filler inside tube before bending operation. Filler contains water and crystal-forming components such as water-soluble salts. Outer diameter of said hose is less than inner diameter of tube. Hose is arranged with gap inside tube and filler is introduced inside it. Gap between walls of hose and tube, filler cooling temperature and salt concentration are selected according to condition providing close contact of surfaces of hose and tube without changing tube shape before its bending at increasing volume of filler due to its freezing. Thickness of hose wall and thermal conductance properties of its material are selected according to condition providing heat insulation between filler and tube while eliminating ice thawing of filler due to increased temperature at process of bending tube and damages of tube inner surface caused by filler ice breaking.

EFFECT: improved quality and efficiency of bending.