Fatigue-resistant heat exchanger main piece flanging structure

The invention provides a fatigue-resistant heat exchanger main piece flanging structure. A main piece is provided with heat exchange pipe holes, and heat exchange pipes are inserted into the main piece heat exchange pipe holes and integrally connected with the main piece in a brazing manner. The main piece heat exchange pipe holes are subjected to flanging in the direction of the outer side of the main piece, the two long edges of flanged edges and fillet edges at the two ends are all higher than four corners, the edge length of the flanged edges can be larger than that of the flat flanged edges, and the main piece flanged-edge edges and the heat exchange pipes form weld seams in the brazing process. In a work state, by means of the outwards-flanged-edge structures of the main piece heat exchange pipe holes, the stress transferred to the heat exchange pipes from the interior of a heat exchanger is totally exerted on the weld seams between the main piece and the heat exchange pipes, the stress of the weld seam