GB1050825A - - Google Patents

Abstract

1,050,825. Making heat exchangers; bending cutters. BORG-WARNER CORPORATION. Dec. 2, 1963 [Dec. 20, 1962], No. 47534/63. Headings B3A and B3W. [Also in Division F4] A stack of heat exchanger fins 7 is formed from strip material by a continuous process in which the strip is folded concertina fashion to form the stack, after having formed therein flanged tube apertures 8 and fin spacing lugs 10 (all formed by die presses 40, 41), and slots 30, 31 along the fold lines, these slots being formed by cutting knives 35, 36. The lugs 10 and tube aperture flanges of adjacent fins 7 in the unfolded strip extend from opposite faces of the strip so that when the strip is folded the said lugs and tube apertures all extend in the same direction in the stack (see, e.g. Fig. 12, not shown); and other apertures 43 with jagged upstanding edges, which in use are air turbilizers, may be formed between the tube apertures. The integral spacing lug 10 is formed from the strip material by the punch assembly shown in Fig. 6. This comprises a die plate 12 in which is a rectangular opening 14, a punch 18 and a stripper plate (not shown). The punch 18 has bifurcated cutting prongs 22 from each of which extends a sloping face A, and cutting edges D associated therewith and a further cutting edge 26 from which extends a sloping face 24. As the punch approaches the strip material 7 the latter is slit by the cutting edges 22 and further movement of the punch cuts the strip by means of the edges D and overturns the severed edges B. Finally the strip is slit along the edge C and the lug so formed is upturned at right angles to the strip by the angled face 24. A punch for forming two lugs similar to the lug 10 shown is described (Fig. 8, not shown). Alternative shapes of lug are shown in Figs. 14 to 16 but no dies for producing these shapes are described.