HEAT EXCHANGER

PURPOSE:To form the heat exchanger having a high strength, a high rigidity and an excellent heat conductive efficiency by holding radiating fins between two tube outer plates molded in wave form. CONSTITUTION:Two tube outer plates 6 are molded into wave form so that the heat exchanger has a plurality of vertical semicircular ribs by use of a plate material having an excellent thickness accuracy. A tube inner plate 7 is held between both plates in a sandwich form, and at both side edges 9 of the tube and the corrugated bottoms 10 of both outer plates, three plates are bonded by welding. The tube outer plate 6 is coated at its outer surface with a brazing metal having a thickness about 10% of the plate thickness. In this structure, coating of the brazing metal is carried out with respect to one surface of each tube outer plate, and hence the brazing metal is saved and the weight of the heat exchanger is reduced. Further, since the section secondary moment is large, local buckling of the tube outer plate hardly occur and the tube inner plate having a thin thickness is substantially on the section neutral line, there is almost no possibility of the heat exchanger being damaged.