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 exchanging apparatuses with use of localized directed plastic deformation of tube material. SUBSTANCE: method comprises steps of making annular trapezoidal cross section protrusions on outer surfaces of end portions of tubes; placing tube into tube opening having annular rectangular cross section grooves; matching annular protrusions of tubes with rectangular cross section annular grooves of tube opening; fixing tube against possible motion for subsequent fastening of it in tube plate due to applying compression effort to inner surface of tube. End portion of tube is preliminarily reduced, and simultaneously outer annular protrusions and inner annular thickened portions of tube are formed. Then outer annular protrusions are calibrated due to axially shifting inner annular thickened portions. EFFECT: guaranteed stabilized size and geometry due to use of technological fitting for tubes of any steel and alloy. 3 dwg