| 摘要 |
PURPOSE:To form splits and both projections and waves having different thicknesses respectively in the surface of a fin, by forming the prescribed recessed grooves in the surface of rolling rolls, in a manufacturing method of a fin to be wound around a heat transfer pipe of a heat exchanger by rolling the fin between rolls. CONSTITUTION:A helical fin 3 is obtained by continuously feeding and passing a fin material through the contacting surface between a large and a small rolling rolls 1, 2 positioned to have a prescribed opening angle between their roll axes. Here, recessed grooves 4 are formed in the rolling surface of at least one side of the rolls 1 and 2. One end of the groove 4 is formed at the position extended further from the passing position of the outer periphery of the fin of the rolling surface of the roll, and the other end is formed at the position short to the passing position of the inner periphery of the fin, so that the projecting surface of the fin is surely produced from the outer peripheral tip of the fin properly to the middle part of it toward the inner periphery side. Thus, the rolling force exerting on the surface of the fin positioned on the groove 4 is smaller than that of the other part, and the elongation of the fin at said position is also smaller, accordingly a fin as shown by the figure is obtained. |
