FEM-Simulation of the Tension Levelling Process with Abaqus/Explicit
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2008 Abaqus Austria Regional Users´ Meeting: Conference Proceedings (CD, Simulia)
Within the production chain of cold-rolled metal strips, tension levelling is either applied in scale breaking devices at the entry of the pickling section of (continuous) pickling lines or in continuous galvanizing or finishing lines as final process step. The main objective of tension levelling is to improve the flatness (i.e. shape) of the strip and to minimize the residual stresses. When running through a tension leveller, the strip is bent alternately around multiple rolls with small diameters, while typically high tension stresses (in the range of up to 70 % of the yield strength) are applied. Due to the combination of bending and tensile stresses, the strip is deformed plastically at each roll resulting in a small elasto-plastic strip elongation, which typically does not exceed a value of five percent. Almost all tension levelling setups are based on rough offline calculations, which have to be supplemented by trial and error procedures during the operation. To improve the design process of tension levelling machines, a precise model is essential. Key objectives of adequate models are the determination of the bending line including the maxima of strip curvature, the analysis of the necessary level of tension, the tension losses due to the plastic deformation as well as the calculation of reaction forces at the bending rolls. All models comprise a large number of parameters describing strip thickness, the geometrical setup of the tension levelling machine, the selected roll positions, the desired degree of elongation, the strip speed as well as elastic and inelastic material properties. To attain a comprehensive understanding of the tension levelling process, different models were created, analyzed and compared by utilizing the non-linear capabilities of Abaqus/Explicit.