Curvature prediction in air bending of metal sheet

The paper describes the use of bending models for air bending and focuses in particular on the importance of adequate determination of sheet curvatures, especially the curvature under the punch nose. After an introduction to air bending, the principles of models which are based on the assumption that the sheet wraps around the punch are described. This ‘wrap-around’ assumption is a limitation and often not in accordance with industrial practice. A method to predict the sheet curvature under the punch, thus eliminating the need for the wrap-around assumption, is discussed and its results are compared with experimental results. The paper then describes how models based on this method can be used to improve adaptive control methods in air bending.