Ball joint apparatus for pressurized fluid lines in the past has incorporated a somewhat flexible bellows between two end tubes encompassed within a protective assembly in the form of a ball joint. Such apparatus as are known include a ball which is welded to one end tube and a housing which is welded to the other end tube. The housing and the ball together establish a ball joint which holds the end tubes and bellows in relative position. Since both ends of the housing are smaller in diameter than the ball member, it has been the practice to fabricate the housing in two pieces and assemble them from both ends of the apparatus so as to enclose the ball member. Thereafter, the two pieces of the housing are welded together by fusion welding.
Ball joints are used in fluid lines to impart limited flexibility for the purpose of accommodating tolerances, thermal expansion and vehicular motion. They can be used in almost any type of fluid line. However, the particular joint under consideration is adapted for use in jet aircraft engine bleed air ducting.
That is, applying the term to a pivotable hollow structure does not mean that the core member is a ball or sphere; neither is the encasing structure (housing) necessarily of a spherical shape, as these terms are used in the mathematical sense. Only when true mathematically defined spherical shape is described in mathematical terms, as in U.S. Pat. No. 5,611,577 ("tri-axial symmetry"), is it intended that terms such as "ball" and "sphere" or "spherical" are to be defining in the precise mathematical sense.
In brief, particular arrangements in accordance with the present invention comprise a bellows and two end tubes for coupling into a fluid line. An inner ball and outer housing surround the bellows to maintain integrity of the assembly. It is a feature of the present invention that the outer housing is fabricated in one piece, thereby eliminating the need for the fusion welding step of previously known ball joint assemblies. There is no fusion welding in particular embodiments of the present invention and only two roll-resistant seam welds are required for assembly.