Manufacturing of bi-direction varying inter-diameter tube

Titanium alloy bi-direction varying inter-diameter tube, which was used for the handle-bar of a high-grade mountain bike was manufactured with a traditional tri-roller tube rolling machine and combined varying diameter core die. The outside diameter of the tube was φ 22.15 mm, its length 558.5mm, and its thickness was 1.07mm at the middle and 0.40mm at each end. The thickness was distributed symmetrically about the middle section and decreased inhomogeneously to both ends. Bi-direction varying inter-diameter tube, with high precision and a smooth surface, could be produced directly with this procedure. The microstructures of the tube along the axial direction were comprised of deformed α + β with different degrees. A service simulation test indicated that the fatigue life of the tube was much greater than that for steel CrMn and aluminum alloy tube, and the weight was less than that for these materials.