GB875603A - Improvements in or relating to a method of joining two metal tubes - Google Patents

Abstract

875,603. Welding by pressure; jointing by tube expanding; working by rotary rubbing tools. CALUMET & HECLA Inc. Aug. 12, 1959 [Aug. 18, 1958], No. 27579/59. Class 83 (4). Two metal tubes are joined by assembling the tubes in overlapping relationship with overlapping surfaces in contact and applying a rotational frictional pressure to the exposed surface of one of the overlapping portions to bring the contacting surfaces to welding temperature. The tubes may be of the same or dissimilar metals. A copper tube 22, Fig. 1, is inserted in the expanded end of an aluminium tube 21 and the assembly is held in a die 26. A tool, e.g. formed of a carbide, having flattened portions 29 and a tapered end 30 and of larger diameter than the bore of the tube 22 is rotated at 2000 ... 2500 r.p.m. and forced into the assembly to expand and weld the overlapping portions 23 of the tubes 21, 22. If desired the contacting surfaces of the tubes may be knurled. In an alternative process the tube 32, Fig. 4, has a reduced end 33 fitting within the tube 31. In this case, a closefitting die 36, Fig. 6, may be used to produce a welded joint of even wall thickness. In a modification, the tubes 41, 43, Fig. 7, are held in clamps 46, 47 and are welded by the action of a rotary die 48 moved axially of the tubes and having a circular die aperture with opposed recesses. If desired a mandrel may be used with the rotary die to produce a weld similar to that shown in Fig. 6.