| 摘要 |
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 deg.C to the m.p. of the solder or below in an oxidative atmosphere and from 300 deg.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. |
