| 摘要 |
PURPOSE:To heighten the productivity and improve the corrosion resistance by a method wherein the open angle of a V-shape gap formed by the parts lying between flow passage grooves of a pair of metal plates is widened. CONSTITUTION:Two sheets of metal plates 8 and 9, having a plurality of strips of parallel groove parts 7, which serve as flow passages 6, are superposed in such a manner that the groove parts 7 face opposite to each other. The metal plates 8 and 9 are joined together with each other by welding together parts 8a and 9a lying between the groove parts 7 by roll-spot welding or the like. After that, gaps 11 made between the parts 8a and 9a of the metal plates 8 and 9 are deformed plastically in a state open in a figure V by increasing the pitches P between joints 10 and applying pressure from the inner part of the flow passages 6. An open angle alpha of the gap obtained after said plastic deformation is 3.6 deg. and more. Local corrosion can be reduced and prevented, because the widening of the open angle alpha of the gap 11 can be performed only by applying pressure. Consequently, the manufacturing work is simplified and furthermore no extra raw material is required. |
