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

FIELD: plastic metal working, namely securing tubes to tube plates of heat exchange apparatuses. SUBSTANCE: method is realized with use of effect of localized oriented plastic deforming of tube material. Method comprises steps of preliminarily profiling tube end with formation of two portions having curvilinear generatrix turned to tube axis and mutually divided by cylindrical land; placing tube end into die that has parting line passing along generatrix and also outer and inner annular trapezoidal cross section grooves; arranging cylindrical land of tube in front of inner annular groove of die; fixing tube against possible motion and forming on it annular protrusions by means of stepped punch; then placing tube in tube plate opening with annular rectangular cross section grooves and matching annular protrusions of tube with annular grooves of tube plate opening; fixing tube against possible motion and fastening it in opening of tube plate due to applying compression effort to inner surface of tube. EFFECT: enhanced efficiency of method due to possibility for making on outer surface of tube annular protrusions having desired geometry and size while maintaining high strength of technological fittings. 8 dwg