METHOD FOR SECURING TUBES IN TUBE GRIDS Russian patent published in 2001 - IPC

FIELD: plastic working of metals. SUBSTANCE: method involves mounting tube in tube grid opening provided with annular grooves; fixing tube against possible displacement and securing it by applying compression force to inner surface of tube by means of rolls. Circular portion with curved generatrix faced to tube axis is preliminarily formed at tube end. Circular portion has length equal to distance between outer edges of opening annular grooves. Upon mounting, this portion is positioned opposite annular grooves. Compression force is applied to inner surface of tube at portion with curved generatrix. Annular grooves of tube grid are initially filled with tube material, with following formation of final rolled connection, with surface layers of tube grid being subjected to the action of extension force. Method allows tubes to be secured in tube grids of heat-exchanging units with the usage of effect of localized directed plastic deformation of tube material. EFFECT: increased efficiency by improved operating characteristics of rolled connections. 6 dwg