Numerical Research on Compound Hydroforming of Ring Parts

The ring parts was formed by the compound hydroforming process of hydraulic deep drawning cylindrical part and then hydraulic bulging. The compound hydroforming process of ring part was simulated with DYNAFORM5.9 software. The influence of preformed cylinder parts on the forming quality of ring parts under different process parameters such as drawing ratio, maximum hydraulic pressure, punch fillet radius and process annealing was explored. The results indicate that the wall thickness of the thinnest point of tubular part and the ring part decreases gradually with the increase of draw ratio. The larger the maximum hydraulic pressure of the process of hydraulic deep drawing of cylindrical parts with single turning point hydraulic loading is, the more severe the wall thickness of the ring is and the smaller the wall thickness of the thinnest point is. As the radius of the punch fillet increases, the wall thickness at the rounded corner of the cylindrical member increases, and the wall thickness at the thinnest point of ring parts decreases after bulging. The intermediate annealing between the two working sequences of compound hydroforming is beneficial to the subsequent processing and the improvement of forming performance.