METHOD FOR FASTENING TUBES IN TUBE PLATES Russian patent published in 1999 - IPC

FIELD: plastic metal working, namely processes for fastening tubes in tube plates by localized directed plastic deforming of tube material. SUBSTANCE: method comprises steps of forming annular protrusions on outer surface of tube end portions; placing tube in plate having openings with annular rectangular cross section recesses and matching protrusions and recesses; fixing tube against its possible axial motion for subsequent fastening of it in tube plate by applying compression effort at side of inner surface of tube; reducing tube end portions before formation of annular protrusions for subsequent formation of trapezoidal cross section protrusions, for example by expanding in die set unit in order to receive outer diameter of protrusions no more than that of central portion of tube. EFFECT: possibility of fastening tubes in tube plates at repairing heat exchangers in condition of acting upon tube plate by normalized effort with provision of enhanced strength and fluid-tightness properties of assembled unit. 5 dwg