Patent ID: 6772831
Filing Date: 2004-08-10
Classification: B21D,F28D,F28F,Y10T

Abstract:
A heat exchanger having tubes through which fluid flows, and fins for promoting heat exchange between one fluid flowing through said tubes and air passing between said tubes, in which said tubes and said fins are joined together mechanically by deforming said tubes plastically so as to increase the cross-sectional areas of said tubes in a state in which said tubes are inserted through insertion holes provided in said fins,wherein said tubes are welded tubes manufactured by bending plate material to form flat tubes and then joining seams by welding, welds of said tubes are provided in areas that are offset from curved portions formed at the ends in the lengthwise direction in the tube cross-section of said flat tube, and depressions that are depressed in the direction of padding of said welds are provided in areas of edges of said insertion holes that correspond to said welds, said depressions being formed at burring portions in either a triangular pyramid shape or a dome-like shape.