Gas=tight joining of pipes having small diameters and different melting points

摘要

When the solder surround zone is heated to soldering point both solder and pipe material heat quickly to join the pipes whilst the soldering temperature is retained. Pipe end (2) is mechanically plugged into the mandrel-expanded end of the lower-melting Al pipe (1) for the solder join. The Cu pipe (3) is then expanded and inserted into the Al pipe so all three pipes can be soldered together. The inside surface of the end-expanded Al pipe is thus intimately joined by the solder to the non-expanded outsides of the Cu pipe. Preferred soldering temperature is 600 deg C, the flux operating within a range 400-700 deg. C and the projecting damper plate connection is joined to the Cu pipe (8) pref. in a single pass. Typically the Cu pipe acts as capillary (3) to fit with pipes (2) into the flared end (1) of the Al pipe.