METHOD FOR CONNECTING TUBES WITH TUBE PLATES AND APPARATUS FOR PERFORMING THE SAME Russian patent published in 1999 - IPC

FIELD: power and nuclear machine engineering, particularly production of tubular heat exchangers. SUBSTANCE: method for connecting tubes with tube plates comprises steps of expanding tubes and inserting unclamped annular welding electrodes to expansion zone for applying to them (at end period of expansion process) welding current for annular contact welding of tubes with tube plate. Novelty is tube expansion along limited-width annular portions in predetermined zones along thickness of tube plate. At first such expansion of all tubes is realized in zone of rear end of tube plate and tubes are tack welded by annular seam. Then strength of all joints is checked, detected defects are eliminated by repeating expansion process and tack welding of all defective joints. The same expansion and tack welding by annular seam is realized in zone of front end wall of tube plate. Apparatus for performing the method includes power cylinder with stop for limiting depth of rod insertion into tube, removable head on end of rod, two changeable cylindrical spacing sleeves freely mounted on rod, turned one to another and having ends with cone surface. Unclamped annular welding electrode in the form of slit collar made of set of sectorized slide blocks movably joined one with another in radial direction is arranged between changeable sleeves. End portions of slit collar have cone surface and they engage with ends of spacing sleeves. Novelty is welding electrode with function of expanding member. EFFECT: enhanced quality of joining tubes with tube plate, enlarged using range of method and apparatus. 14 cl, 4 dwg