Research On Variable Cross Section Tube Hydroforming Process

In modern society, tube hydro-forming technology has been increasingly favored as a new type of clean and flexible process; it was widely used to produce hollow and variable cross-section parts in the fields of automobiles and aircrafts. Therefore, variable cross-section tube hydro-forming process is of great realistic significance to promote China's automobile industry into the world's most advanced rank.Through consult a large number of domestic and foreign literatures, the basic theory of tube hydro-forming process has been studied, the tube deformation characteristics in the forming process was clearly understood, the influence of loading path on different forming stages was also analyzed in this paper.Secondly, the tube hydro-forming equipment was investigated, two sets die cavity were designed for the spindle bursting and engine cradle experimental research respectively. Thus, a set of data detection system was designed, the system can adapt to the on-site experiments environment with interference factors and poor dynamic medium-signal.Through the tensile test in room temperature, tube forming performance parameters are obtained, and the effect of tensile speed on these parameters is researched; through spindle bursting test, the influence of loading path on forming limit is further studied. According to these tests, several loading rules are summarized.Finally, the simulation and experiment research of engine cradle hydro-forming are carried on to study the effect of loading path on the complex cross-section forming, the qualified forming pieces are obtained by defining the forming quality factor to choose the loading path for the experiment. From the analysis of various experiments phenomenon at the micro-organization, it is found that work hardening can hinder the tube's further deformation and the wall thinning is only related to the circle tensile stress and axial compression press.