Research On Optimization Of Process And Springback Compensation Methods In Three-dimensional Stretch Bending Of Aluminum Profile

In recent years, with the weight reduction technology is applied in high-speedrail train industry, the safety performance of train is improved, energy consumption issaved, and great convenience is brought to our lives. Currently, there are two ways toachieve lightweight vehicles, one is the use of lightweight materials, and the other isthe use of frame structure consisting of curved member profiles. The aluminumprofile stretch bending components satisfy both lightweight and the strength demands,and are widely used in the manufacturing of the body of rail vehicles. With the shapeof the design of the vehicles are more and more complex, components of body framebending pieces are no longer confined to simple plane bending members, and moreand more special parts are used.In this paper, three-dimensional stretch bending process of structural componentsof rail vehicles was numerically simulated; the finite element models were formed.The issues involved in the modeling process such as materials’ parameter settings,boundary conditions’ settings, and die units and so on were discussed in detail. Thebasic theory of stretch bending, the adjustment of the flexible bending dies and thecalculation of displacement and the angle of die units were also described.The forming simulations on the three-dimensional stretch bending of structuralcomponents of rail vehicles were carried out, and the analysis of the results werefocused on the following aspects: stress, strain, forming accuracy, as well ascross-sectional torsion. First of all, the influence of die units on the quality of the partswere analyzed, the number and width of the three-dimensional flexible bending dieunits has been determined. The results showed that the number of die units have thegreatest impact on the shape accuracy of the work piece. The number of die unitsdecrees, the average shape error and the accuracy become bad. Increasing in the number of die units will improve the accuracy of the formed pieces. Variations in thenumbers of die units make a little effect on the maximum equivalent stress andminimum equivalent stress on the final product. However, when the number of dieunits is very small, dimpling and non-uniform stress distribution will be generated.The width of die units gets small, the discrete die shape close to the target shape,thereby forming precision gets well. The influence of the degree of three-dimensionaldeformation on the formed part was studied.The factors affecting the forming parts’ springback such as pre-stretching,post-stretching and the friction were studied by using the orthogonal test. The resultsshowed that with the increase of friction, springback of the forming parts in horizontaland vertical directions will become larger. When the amount of the pre-stretching is1.5%, the amount of post-stretching is1.0%, formed parts with the minimumspringback can be obtained. The method for springback compensation inthree-dimensional flexible stretch bending was studied and the experiments provedthe feasibility of the method in improving the accuracy of the forming parts.