Development of levelling strategies for heavy plates via controlled FE models

© 2017 The Authors. Published by Elsevier Ltd. Accurate levelling strategies to ensure the flatness of heavy plates are crucial for a high level of productivity in the plate mill. As heavy plate levelling is typically a multi-pass process, it is important to identify levelling strategies that deliver the desired plate flatness with minimum effort. Due to the high sensitivity of the actual roll positions in the leveller on the incoming material properties and plate geometry, a unique machine setup has to be determined for each combination of material and geometry. Besides, successful levelling strategies have also to consider the incoming plate profile. A method to quantify windable and non-windable defects as well as ski defects by characteristic values suggested earlier is briefly repeated. To investigate the influence of the incoming defects on the outgoing flatness, conventionally numerous FE simulations have to be performed. This is caused by the fact that a single set of roll positions is required that delivers a defined plastification ratio and a flat plate at the same time. Within this work, a closed-loop controlled FE model is presented that is capable of evaluating the required set of roll positions within a single pass. Coupling the information obtained by a multiple of different simulations with results from an online flatness gauge will establish a methodology to derive an efficient process design. In the future, this will enable knowledge of an appropriate levelling strategy to eliminate the incoming flatness defects and to predict the time required for levelling prior to the first pass.