METHOD FOR MAKING HEAT EXCHANGE TUBES Russian patent published in 2001 - IPC

FIELD: plastic metal working, namely manufacture of tubes secured to tube plates of heat exchange apparatuses at using effect of localized oriented plastic deformation of tube material. SUBSTANCE: method comprises steps of cutting off part of measured length of tube after straightening tube and trimming outer surfaces of tube ends; then forming tube portion with curvilinear generatrix turned to tube axis and placing tube end into opening of detachable die having outer and inner annular grooves on its inner surface; placing tube portion with curvilinear generatrix in front of inner annular groove of die; fixing tube against possible motion and forming on it annular protrusions at applying to tube end axial effort causing deformation of tube material and plastic yielding of material to annular grooves of die; simultaneously providing axial motion of die at rate equal to that of tube material deformation in order to make equal outer diameters of annular protrusions of tube at applying relatively small deforming efforts. EFFECT: enhanced efficiency. 8 dwg