Light Weighting through Tube Hydroforming 2014-28-0013

Environment, energy and safety concerns for vehicles have made improving strength-to-weight ratio of vehicles an imperative issue for the automobile industry. Tube hydroforming (THF) is an innovative forming technology, which can efficiently reduce the weight of a component or assembly, and at the same time, increase the part strength. THF produces parts with a high degree of part complexity (various cross-sections in a single piece) and dimensional stability. Tube hydroforming involves the expansion and sizing of tubes in a closed die under dynamic action of pressurized fluid, with simultaneous axial or radial compression. Best forming results can be achieved by the optimized combination of process parameters (internal pressure, feed, friction, load, blank thickness) and material properties (yield strength, tensile strength, n-value, r-value, elongation).With the help of case studies, this thesis presents how tube hydroforming has been used to shave mass off some conventionally produced auto components like chassis cross-members, trailing arms, crash members and exhaust housings. Present work elaborates the design and manufacturing aspects along with improvement in part properties and per piece cost reduction accrued by changing over to tube hydroforming. Tube hydroforming makes a very compelling case for changeover where both weight reduction and strength increase are simultaneously desired. Tubular hydroforming has other intangible benefits such as product integrity improvement (by minimizing joining by welding), improvement in NVH and safety parameters.