METHOD FOR ATTACHING TUBES IN TUBE GRIDS Russian patent published in 2002 - IPC

FIELD: plastic working of metals, in particular, attachment of tubes in openings of heat-exchange units through the effect of localized directed plastic flowing of tube material. SUBSTANCE: method involves placing tube in grid opening equipped with annular channels; fixing it from possible movement and securing by applying deforming force to its inner surface, with tube end being preliminarily profiled for forming annular projection on its inner surface; forming no more than three equally spaced openings in tube wall along perimeter of annular projection; filling openings with plastic material in the form of core. Tube is placed in tube opening of grid, with annular projection being in cantilevered relation to outer edges of annular channels. Aluminum may be used as plastic material. Such construction allows rolled connections to be tight and corrosion resistant and tube grid to be prevented from warpage. EFFECT: increased strength and improved quality of connections. 2 cl, 4 dwg