| 摘要 |
1,073,972. Making heat exchangers; stamping; rolling. REYNOLDS METALS CO. July 8, 1964 [July 9, 1963], No. 28209/64. Headings B3A, B3M and B3Q. A method of making a heat-exchanger panel 32 having a tubular passageway between two sheets of material of which at least one sheet is of a work-hardenable aluminium alloy, comprises bonding the sheets together, and introducing an inflating fluid under pressure between the sheets to form the passageway in the aluminium alloy sheet, this sheet upon inflation to separate the bond producing a sharp wedg formation (120, Fig. 9), moving ahead of th inflating fluid so as to avoid the formation of restrictions in the passageway. After rollbonding, the sheets are partially annealed to render them readily formable without being too soft, so that the desired sharp inflation wedge results. Two or more sheets 32 of aluminium alloy having the following constituents may be used: Si 0À3% Fe up to 0À7% Cu up to 0À25% Mn 1À0-1À5% Mg 0À8-1À3% Zn up to 0À25% Impurities up to 0À15% Balance Al. Adjacent sheets may be of different metals or alloys. The sheets 32 are dry-annealed in a furnace 30 and wire-brushed at 34 before they are placed together with unclad surfaces in contact and secured by spot-welding 38. Stopweld 40 is painted on one of the sheets where the inflation needle is to be introduced. The sheets are heated in a furnace 42 to the desired temperature for roll-bonding between rolls 46. Further hot and cold-rolling operations follow, between rolls 50, 52. Partial annealing to approximately quarter hardness is then effected. The stop-weld area is then expanded by a wedge 54 to receive the inflation needle 66, with the sheets sandwiched between dies 58, 60, one or both of which have tube-forming grooves. Holes (Fig. 2) in the panel may locate on pins in the lower die 58. Oil, water or gas may be used for inflation; any residue of distilled water may be removed by evaporation. The die-passages have air vents and various cross-sections (Figs. 7, 8, 21). In an example, two sheets of the aluminium alloy are heated to 900-1000‹ F. and hot-rolled at about 920‹ F., with a reduction of 75%. A second hot-rolling at 600‹ F. follows, with a reduction of 14À3%. The panel is then flattened by coldrolling, annealed to quarter hardness by heating to 600‹ F. for approximately thirty minutes, and cut to size. An inflation pressing of 15,000 p.s.i. is applied and the panel removed from the dies and sheared to final size, for use with a working pressure of 600 p.s.i. In another example, a reduction of 72% is effected in the first hot-rolling and 14À3% in the second. In a further example, a first hot-rolling reduction of 64% is followed by a second of 30% and then by a cold-rolling reduction of 10%. A bond of minimum strength could be achieved by a first hot-rolling with a reduction of 50-60%. |
