| 摘要 |
PURPOSE:To improve adherence between an inner tube and an outer tube, by a method wherein the thin layer of a low melting point metal, such as solder, tin, lead or the like, is provided on the surface of a copper tube, a steel tube or the like through plating method, while the thin layer of the metal is melted to coat a lead tube or a lead alloy tube. CONSTITUTION:The surface of a copper tube 1 is pickled or ground, and thereafter the thin layer of solder 5 is provided by plating method and the layer 5 of the solder is heated to a molten condition while the copper tube 1 is covered by a lead alloy tube 2 under this condition. Accordingly, the inner tube 1 of copper and the outer tube 2 of lead alloy are adhered well through the layer 5 of the molten solder and an air layer or the like will never be formed between both tubes. Therefore, heat resistance is small and heat transfer coefficient is good. Further, the outer tube will never be deteriorated locally. Furthermore, the outer tube 2 will never swell locally and the film of lead sulfate, formed on the surface of the outer tube, will never scale off, whereby the heat transfer tube may be used for a long period of time.
|
