METHOD FOR FASTENING TUBES IN TUBE PLATES Russian patent published in 2000 - IPC

FIELD: plastic metal working, namely processes for fastening tubes in tube plates of heat exchanging apparatuses with use of effect of local directed plastic deformation of tube material. SUBSTANCE: method comprises steps of making annular protrusions with trapezoidal cross section on outer surfaces of upper end portions of tube; placing tube in opening of tube plate having annular grooves with rectangular cross section; aligning annular protrusions of tubes and annular grooves of openings; fixing tube against motion and then securing tube to tube plate by applying compression effort to inner surface of tube. Annular protrusions with trapezoidal cross section are formed in conditions of axial thrust at making additional annular protrusions due to compressing tube by thickness at applying increased effort to outer surface of tube outside formed annular protrusions. Parameters of tube joints are increased in average by (50-70)% due to formation of additional annular protrusions. EFFECT: enhanced properties of joints of tube with tube plate. 5 dwg