METHOD FOR PRODUCING CROSS-FIN TUBE FOR HEAT EXCHANGER, AND CROSS FIN-TYPE HEAT EXCHANGER

摘要

An advantageous method for producing a cross-fin tube, and a cross fin-type heat exchanger with the cross-fin tube obtained by the method. In a cross-fin tube obtainable with the method, neither evaporation characteristics nor condensation characteristics are impaired when a heat transfer tube with inner surface grooves is expanded in diameter by mechanical tube expansion operation to integrate the heat transfer tube and heat radiation fins. On the outer surface of a tube expansion plug (18) are provided 60 to 160 lines/circumference of cut ridges (28) in a direction intersecting primary grooves (20) that are provided in advance in the inner periphery of a heat transfer tube (10). The heat transfer tube (10) and plate fins (12) are integrated into one piece by mechanical tube expansion. Secondary grooves (24) intersecting the primary grooves (20) are formed such that their depth (d2) is within the range between 10% and 40% of the depth (d1) of the primary grooves (20).