Abstract: An improved method for producing a basic B tube configuration for a folded heat exchanger tube (26). A braze clad metal strip (10) having inner (1) and outer (0) surfaces and a opposed edges (12) is progressively formed over and in by a series of progressive roller stations (14A, 16A-14J, 16J) until the lower edges (12) on a pair of central abutting flanges 18 centrally engage the strip inner surface (1). Between two of the roller stations (G and H), a powered dispense valve (20) with nozzle (22) continuously dispenses a bead (24) of material containing flux or, alternatively, flux and braze material. Bead (24), rather than being a thin stripe, is a thick semi cylindrical shape, with substantial viscosity. As the flanges (18) move into abutment and the downstream roller stations, the flange edges (12) are forced down into the bead (24), some of which is pumped up between the outer surfaces (0) of the abutted flanges (18), yielding a good, solid braze joint between the two.

Abstract: An improved method for producing a basic B tube configuration for a folded heat exchanger tube (26). A braze clad metal strip (10) having inner (I) and outer (O) surfaces and a opposed edges (12) is progressively formed over and in by a series of progressive roller stations (14A, 16A-14J, 16J) until the lower edges (12) on a pair of central abutting flanges 18 centrally engage the strip inner surface (I). Between two of the roller stations (G and H), a powered dispense valve (20) with nozzle (22) continuously dispenses a bead (24) of material containing flux or, alternatively, flux and braze material. Bead (24), rather than being a thin stripe, is a thick semi cylindrical shape, with substantial viscosity. As the flanges (18) move into abutment and the downstream roller stations, the flange edges (12) are forced down into the bead (24), some of which is pumped up between the outer surfaces (O) of the abutted flanges (18), yielding a good, solid braze joint between the two.