| 摘要 |
965,488. Heat exchanger tubes. F. ROFFELSEN. May 3, 1962 [July 18, 1961], No. 17036/62. Heading F4S. [Also in Division B3] In making a heat exchanger element a wire helix having concavely arcuate parts in the turns is secured to a flexible metallic strip supporting solder, the unit so formed is applied helically to a tube with the strip between the wire helix and the tube and heat is applied to solder the wire helix to the tube through the concavely arcuate parts. The wire helix 4, Fig. 1, may be soldered or welded to a strip 6 of wire fabric prestressed longitudinally and impregnated with solder so that when the helix and strip are helically wound on to a tube and heated, the strip contracts and the solder bonds the strip to the helix and to the tube. The support may alternatively be a thin metal strip having slots extending alternately from its opposite edges and the slots accommodate solder. The support may alternatively comprise a flat pressed hose 9, Fig. 4, of wire fabric or braid retained by solder impregnating the hose and the helix and support are wound helically on to a tube 11 and this tube is inserted into a heat exchanger tube 12 and the assembly heated so that the hose springs into contact with the inner wall of the tube 12 and when cool is soldered thereto and to the helix. The tube 11 is then withdrawn. To secure the wire helix to its support, the latter may be wound helically on a cylindrical surface of porcelain, glass, cast iron or chromium, a solder strip is wound thereon and over the solder is wound the helix and the assembly heated to melt the solder. Specification 965,489 is referred to. |
