METHOD FOR SECURING TUBES TO TUBE PLATES Russian patent published in 2001 - IPC

FIELD: plastic metal working, namely processes for mounting tubes in openings of tube plates at using effect of local oriented plastic deforming of tube material. SUBSTANCE: method comprises steps of placing one end of preliminarily prepared tube in tube plate opening having two annular grooves; fixing tube against its possible motion and fastening it in opening of tube plate by expanding at applying compression effort to inner surface of tube; reducing tube end before placing it in opening of tube plate at increasing deformation degree for forming two cylindrical portions joined by cone transitions; forming annular grooves of tube plate openings with cross section in the form of triangle whose apex is directed towards front surface of tube plate; placing tube in opening of tube plate with minimum gap; arranging cone transitions of tube in front of annular grooves of tube plate opening; realizing expanding process by two stages: at first stage applying compression effort to surface of maximally reduced cylindrical portion of tube. EFFECT: possibility for achieving desired operational characteristics of expanded joint without increased compression efforts. 7 dwg