Key Process Research On Hydroforming Of Abnormity Tube

The hydroforming of Abnormity Tube using liquid to apply high internal pressure to the tube so as to make the tube deformed along radial is a new forming process of plastic forming, which belong to the tube deep process technique.category. it iniatiated in the years of 60th of 20th century and with the increasing demands of auto industry in the past 10 years, many foreign countries have paid more and more attention to the technique. It not only simplified the tooling structure, but also can manufacture many parts with complex surface such can not be manufactured by other forming process. It has the significant meanings in improving the stability and the integrative mechanical performance of the auto components, reducing the amount of process and working procedure, saving material, reducing costs and lessening the deadweight of the automobile. Further more because of the well stress state when hydroforming, it can achieve greater deformation than other forming process. It can compound with other working procedure such as bending, marking, and punching so as to achieve greater economy benefit. The hydroforming of Abnormity Tube can carry through in common hydraulic press or special hydroforming press.The so-called Abnormity Tube is the anomalistic shape tube relativing to the straight tube and in the practical application the T-shape tube, multibarrel tube, different diameter tube, protruding rib tube and corrugation tube are the familiar shape. This paper deals with the different diameter tube, all the Abnormity Tube are widely applied in the industry.On the base of absorbing domestic and overseas literature information, the result of expanding rate reaching 1.8 has been first time simulated in domestic. The hydroforming process and the forming rule has been analysed, the choice of the expanding medium, the confirmation of the origin tube size, the material forming capability, the implement method of tube hydroforming of has been investigated. By using finite deform theory, movement equation and boundary condition, the finite element calculate formulas for Abnormity Tube Hydroforming has been induced and the explict solution method of the displacement field based on the time middle difference has been given. In addition, some other key issues such as numerical integral method, stress-strain calculation and the disposal of boundary condition have also been lucubrated. By using the dynamic explict finite element simulation software -DYNAFORM, the results that the effect of the loading path on the forming process and the relationship between the friction coefficient and the distributing of the thickness of the tube have been achieved. And also achieved the expanding working chart by analyzing the forming failures. Meanwhile, the design principle of the cross section of the abnormity tube, the principle of mould design and the confirmation method of the tube material characteristic have been brought forward too.The analysis method and the conclusion of this paper has relatively universal guidance and reference meanings to the forming of hollow parts.