Dynamic analysis and control of a roll bending process

Recent research has shown that it is possible to automate the roll bending process using closed-loop control, which continuously calculates the springback of the metal workpiece. This means that one-pass forming of arbitrary two-dimensional workpiece shapes is now possible, subject to limitations of the physical apparatus and the controller. The identification of these limitations is the subject of this paper. Toward that end, dynamic models are developed for the individual components of the roll bending apparatus and for the process as a whole. These models include the unique nonlinearities of the roll bending system and also reflect the differences in the bending applications, such as bending and straightening. The process models are the basis for control analysis and design. An experimental roll bending apparatus is used to evaluate the system models and to verify the control design. The experimental results show that very good system response is possible using a simple controller. The results also illustrate the main limitation imposed on system response, which is due to vibration of the workpiece.