Fea Of Stress And Deflection In Dies Of Tube Hydroforming

Dies play a key role in tube hydroforming. Especially the die structure has significant influence precision of the shape and dimensions of a formed part, and the largish scale of formed part cost is that the expenses of die, so the cost of formed part is greatly affected by the die's intensity and service life. As the hydroforming application increases, the requirement on service life and die accuracy is also enhanced, many problems about die design appear and are studied.In this dissertation, finite element method is used to reveal stress and deflection in a hydroforming die, for two kinds of loading paths. According to the simulation results, the deflection values and the maximum principal stress values in the hydroforming die, under the closing force matching with the internal pressure, are smaller than those under the constant closing force, not only benefit in controlling the hydroforming, but also preventing catastrophic fatigue failure of possibility and increasing service life of dies.In addition, based on the assumption of an effective circle, the deflection and the maximum principal stress in the dies under varying internal pressure are studied. And then the relation of the die thickness size and circle diameter is analyzed. A basic principle for die thickness design is presented, which is possible to be a guidance for design of hydroforming dies.In this dissertation, the parting surface of the dies with rectangle chamber is studied. Both cases, the fillet radius of the top and bottom mold being equal and unequal to each other are analyzed. The position of the parting surface affects the stress and deflection of the dies. According to the results of the stress and deflection in the dies under internal pressure, the design principle of the parting surface position is presented, which is applied to reduce fatigue failure and to be a guidance for service life of dies.Furthermore, the trapezoid chamber die was studied. Through finite element analysis, two structures of dies are studied, it is found that, the selflocking design on the dies is effective, the deflection at the edge of the hydroforming die and the maximum principal stress at the fillet region of the die...