METHOD FOR SECURING OF PINS IN HEAT-EXCHANGE UNIT TUBULAR COILS Russian patent published in 2003 - IPC

FIELD: plastic working of metals. SUBSTANCE: method involves manufacturing pins with profiled ends and inserting into tubular coil openings provided with outer and inner annular channels, which are made in the form of depressions arranged concentrically to opening axis in zones adjoining to opening ends; fixing pins from possible displacement and securing in tubular coil openings by applying force exerted by die to internal surface of profiled ends; profiling ends of pins for forming supporting portion and portion to be loaded, and intermediate conical portion. Supporting conical portion has outer diameter, which is selected on condition that supporting portion be arranged with minimal gap with respect to inner annular depression. Portion to be loaded has outer diameter smaller than diameter of tube opening. When pin is positioned in tubular coil opening, supporting portion of each profiled end is inserted into inner annular depression of related opening. When pins are secured in tubular coil openings, they are preliminarily fixed on edges of outer annular depressions. Method may be used for manufacture of U-shaped heat-exchange units by realizing the effect of localized directed plastic deformation of pin material. EFFECT: increased efficiency by providing non-detachable connection of pins to tubular coils undergoing contact pressures increasing during operation of heat-exchange units. 5 dwg