| Popis: |
One key challenge in the processing of flexible media, such as thin aluminium films, is to obtain rolls without any aspect defect which can seriously damage the material. The “defects” (i.e. wrinkling or buckling) are due to the fact that the stress generated within the roll is greater than some “plasticity threshold”, then it is crucial to predict the internal stress. Offline optimization of the tension reference can a priori guarantee the production of perfect rolls, with respect to the internal stress. Nevertheless, due to the imperfections of the winding systems, the control systems never generate perfect follow-up of the tension reference value. It is therefore judicious to change online the tension reference value, according to same criterion. The method proposed here is based on the minimization of a cost function, and it consists in adjusting the stress values within a roll, by prescribing a gauge. This gauge can be constant or varying as the roll being wound. Several illustrative examples are presented and commented. |
