PURPOSE: To reduce stages and to eliminate the need for a waste water treatment by performing a pretreatment stage prior to welding of a heat exchanger made of Al or an Al alloy by a heating treatment without defatting and chemical cleaning.
CONSTITUTION: A heat exchanger is produced by a stage for assembling the tubes and fins of the heat exchanger consisting of Al or an Al alloy clad with a brazing material on at least the tubes or fins, a pretreatment stage prior to brazing, a flux adhering stage and brazing stage. The pretreatment stage prior to the brazing is performed by heating the tubes and fins from 250°C to the m.p. of the solder or below in an oxidative atmosphere and from 300°C to the m.p. of the solder or below in a mixed atmosphere of one kind or ≥2 kinds among the air, hydrogen, oxygen and inert gas or in vacuum.
FUKUMAKI TAKASHI
FUNAMOTO TAKAO
