Simulation Of The Multi-tube Hydraulic Bulging And Its Controlling Model Study

Tube plastic forming has been an important research direction of the 21^st century in advanced plastic process techniques as the result of its characteristic of light weight, high ductility, low consumption and precise production. Tube bulging, as one aspect of the tube plastic processing techniques, has become a researching hot pot of this field. With the development of the computer hard & soft ware and the FEM (finite element method), FEM have been adopted as one of the new methods to forecast the distribution of stress and strain during tube bulging processing, and the matching of technical force. The deficiency, such as wrinkle and crack can be simulated. Besides, using FEM, the cost will be reduced and the production cycle will be shortened.In this paper, the forming proccess of Tee tube hydro forming (THF) were studied in detail. Finite element model of THF was established. The influence of processing parameters to the axial compressive bulging was analyzed. Loading path of each parameter in the compound bulging was studied. T-tube bulging with solid medium and liquid was compared. Finally, controlling mode of THF system was analysed. The main contents are introduced as follows:1 FE model of THF was established, and the influence of the friction between the tube and the dies, radius of corner, tube thickness and the initial length to the branch height and the ratio of top branch wall thickness reduction were studied. The variation of two-way tensile stress, strain distribution and branch height in the axial compressive bulging and compound bulging were compared respectively.2 Three factors ( inner pressure, axial feeding, counter pressure) of Tee tube compound bulging to the branch height were studied using the orthogonal test, and the impact subsequence of the three factors to the process was obtained from it. It was found that inner pressure influenced the tube compound bulging mostly.3 Based on the orthogonal test, initial increasing velocity of inner pressure, feeding speed of the axial punches, the size of counter pressure and its starting loading time to the product branch height were analysed. Five loading schemes were designed through combining the loading path of each parameter, and an optimizational loading scheme was selected after comparing the branch height, wall thickness distribution, stress-strain distribution got from each scheme.4 FE model with solid bulging medium was established, and the results got from the simulation were compared with those from hydro forming. It is found that,...