METHOD FOR FASTENING TUBE IN TUBE PLATES Russian patent published in 2001 - IPC

FIELD: plastic metal working, namely, fastening of tubes in tube plates of heat exchange apparatuses with use of effect of oriented localized plastic deformation of metal. SUBSTANCE: method comprises steps of forming on tube annular cross rigidity ribs for preventing unexpected axial yielding of tube material at forming annular protrusions. Annular rigidity ribs are formed by locally reducing tube and by subsequent irreversible expansion of reduced tube portions to initial geometry size. Then tube is placed in die parted along its generatrix and fixed against axial motion. On outer surface of tube end trapezoidal cross section annular protrusions are formed. Tube with protrusions is placed in tube plate opening having on its surface annular rectangular cross section grooves. Annular protrusions of tube are matched with annular grooves of opening. Then compression effort is applied to inner surface of tube for fastening tube in opening of tube plate. EFFECT: enhanced strength characteristics of joints. 7 dwg