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 placing one end of tube in floating die that has parting line passing along generatrix and annular trapezoidal cross section grooves; fixing tube against its possible motion by means of clamp whose working end is in the form of cone surface; forming gap at placing tube to die between cone working end of die and working end of clamp; placing stepped punch in tube; forming annular protrusions in outer surface of tube end portion at axially moving punch; providing compression stresses on outer surface of tube in said gap due to arranging generatrices of cone surfaces in such a way that to press out tube material into gap with possibility of separating excess tube material arranged in gap from outer surface of tube; then placing tube in opening of tube plate having annular rectangular cross section grooves; fixing tube against its possible motion and fastening it in opening of tube plate at applying compression effort to inner surface of tube. EFFECT: enhanced operational characteristics of "tube-tube plate" joints due to formation of annular protrusions of tube with desired geometry and size. 5 dwg