Finite Element Analysis on Spread for In-plane Roll-bending Process

The in-plane roll-bending process is a special wedge rolling with a configuration of two conical rolls which can form strips into open ring products. The spread of a ring is usually not considered in previous radius predicting models by Yang et al. [1] and Xian et al. [5]. However, the spread increases to 10% for a ring with average reduction of 56%, and there is a discrepancy between the predicted radius and the experiment. Spread analysis/calculation has become an urgent problem in radius prediction and precision control of unequal deformation in this process. A finite element (FE) model considering spread effect is established and evaluated by experiments. A comparison between the predicted results with/without considering spread by FE analysis and experiments is carried out. The result shows that the predicted results considering spread are much closer to the experiments than those without considering spread effect. Based on the FE simulation, the spread characteristics of the ring with two types of cross section (including partly and entirely compressed cross section) are investigated. It is found that, there exist three spread regions, including outer positive region, middle negative region and inner positive region for the partly compressed ring; and there are outer positive region and inner negative region for the entirely compressed ring. The spread mostly happens at the outer positive region for both types of ring. The effects of process parameters, such as wedge angle, bite location, friction coefficient and rotational speed of roll, on spread for three aluminum alloys, 3A21O, 5A02O and 2A12T4, are investigated. The results indicate that the spread decreases with an increase in wedge angle, whereas increases with the growth of bite location; the spread remains stable with increasing friction coefficient and fluctuates within 3%-8% with a rise in rotational speed of roll. The spread of the partly compressed ring is less than 6%; large spread (larger than 6%) occurs when the ring is entirely compressed; the spread may reach a maximum value of 18.8% for material 5A02O.