To obtain a method of forming a tube for heat exchangers by which a desired folded part is obtained while simplifying the shape of the folded part and preventing the generation of a clearance and a crack.
When constituting the folded part 5 by forming a pair of V-grooves 5a, 5b, the angle of which is rectangular or obtuse on both sides of the center-line C of folding on the side of the inside of a metal sheet 4, also providing the relief part 5c of a material for the compression of the sheet between those groves 5a, 5b and constituting flow passages 3 by a plurality of lines of projections 6 and grooves 7 which are symmetrically formed by taking the folding part 5 as a boundary by folding the metal sheet into two in the folding part 5 by taking the V-grooves 5a, 5b as the reference point, because the material which is swollen when the slopes of the V-grooves 5a, 5b are compressed can be relieved by the space parts 8 formed in the relief part 5c and compression on the inside of folding and elongation on the outside of folding are mitigated; the folding of the part folded in two is facilitated and also the generation of the clearance on the inside of folding and the generation of the crack on the outside of folding can be efficiently suppressed.
COPYRIGHT: (C)2008,JPO&INPIT
Iwa Saki Kokuni
Kawamata Sumio
Masakazu Ito
Shunichi Takahashi
Toshio Takamatsu
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