Controlled solid-liquid transition during twin-roll casting

在成形过程中，刀具对工件具有高度的非线性影响，分布在时间和空间上。现有的控制模型和方程不能考虑成形过程的变化，如合金成分、成形速度变化、温度等。作为一种典型的成形工艺，镁合金的双辊铸轧是指成形前在加工区进行的一次成形过程。由于水口和轧辊之间的自由表面以及凝固区位置和形状的先验未知，双辊铸轧是一个自由边值问题和亚稳态问题。在工艺控制方面，由于缺乏弹性测量数据，双辊铸轧对所产生的材料性能只有部分了解或评估。由于缺乏测量数据，特别是铸造过程中凝固区域的位置和形状，给测量和模型带来了不确定性。在目前的项目中，这些不确定性将通过新开发的集成在卷筒中的传感器系统来消除。目前，在整个材料的成形过程中，任何时候都不能检测到显微组织和最终带材性能。因此，并不是所有的干扰因素都可以在模型中考虑。现在，通过定量测量铸轧间隙中的应力状态以及温度和热流，可以消除阻碍对铸轧过程进行稳健的、基于性能的控制的不确定性。必须开发强大的测量系统和软测量，以便在动态测量期间根据可测量的量可靠地估计微结构条件。预计合作将从根本上增加关于弹性、显微组织和性能控制成形工艺设计的知识。

In forming processes, the tool has a highly non-linear effect on the workpiece, distributed over time and space. Existing control models and equations cannot take into account the variations due to the forming process, such as alloy composition, forming speed variations, temperature, etc. As an exemplary forming process, the twin-roll casting of magnesium alloys is used, in which an primary forming process takes place in the process zone prior to forming. Due to the free surfaces between nozzle and rolls as well as the a priori unknown position and shape of the solidification area, twin-roll casting is a free boundary value problem and metastable. In terms of process control and, due to the lack of resilient measurement data, twin-roll casting in connection with the resulting material properties is only partially understood or evaluated. Measurement and model uncertainties are given by the lack of measurement data, especially for the position and shape of the solidification range during casting. In the present project, these uncertainties are to be eliminated by a newly developed sensor system integrated in the roll. The microstructure and the final strip properties can currently not be detected at any time during forming in the entire material. Thus, not all disturbing factors can be considered in the model. The uncertainties that stand in the way of a robust, property-based control of the casting-rolling process are now to be eliminated by quantitative measurements of the stress state as well as temperature and heat flow in the casting-rolling gap. Robust measuring systems and soft sensors have to be developed which allow the microstructural condition to be reliably estimated from measurable quantities during dynamic measurements. The cooperation is expected to lead to a fundamental increase in knowledge about the design of resilient, microstructure- and property-controlled forming processes.