| 摘要 |
PURPOSE:To execute the brazing at a lower temperature than before, to remarkably reduce the brazing cost, and also, to use a high strength stock of a low melting point which cannot be used up to the present. CONSTITUTION:Immediately after A1 or an A1 alloy stock is subjected to hot extruding of tube stock, the extruded stock concerned is allowed to pass through the inside of a plating tank of a Zn or Zn alloy brazing filler metal and the outside of the tube stock is covered with the brazing filler metal concerned, the extruded tube stock covered with the brazing filler metal is formed as a tube, this tube stock is assembled to a core consisting of an A1 or A1 alloy bare fin and heated and brazed, by which each constituting parts are joined by the brazing filler metal on the surface of the tube stock. Subsequently, the brazing filler metal layer is coated to thickness of 5-100mum, and also, at the time of brazing and heating, a diffusion layer in which Zn is 10-100mum is formed and a sacrifice layer is provided, and moreover, it is desirable that an oxide film on the surface of the A1 or A1 alloy tube is eliminated by applying an ultrasonic wave into the plating tank. |
