In a manufacturing method of a heat exchanger including a core portion having a plurality of tubes and a plurality of radiation fins connected to surfaces of the tubes, and a tank portion communicating with the tubes, a preheating step, a brazing step, a gradual cooling step and a cooling step are performed...http://www.google.es/patents/US6625886?utm_source=gb-gplus-sharePatente US6625886 - Manufacturing method of heat exchanger
