大直径薄壁管双扩口成形机理与工艺研究

To investigate the double flaring forming mechanism and process of large diameter-thin wall tube, finite element method combined with experiment was used, and a multi-step stamping double flaring forming and springback finite element model of large diameter-thin wall aluminum tube was established. With the model, the stamping double flaring forming process was divided and described based on load-displacement curve and the deformation behaviors of double flaring forming tube, and the forming mechanism was revealed. The study shows that there exists the defect of uneven inner layer which is mainly caused by the upper die flaring force on the arch inner layer(formed by the inversion of straight wall segment)of the tube end. The defect is mainly affected by the parameters of inversion punch. In the case of using a fillet punch, when the fillet radius is 3 mm≤r≤4 mm, the forming quality of double flaring tube is good. When using a conical punch and the half-cone angle is 60°≤φ<70°, the tube forming process is stable, and the inversion result is great.