Controlled solid-liquid transition during twin-roll casting

在成形过程中，刀具对工件具有高度非线性的影响，并随时间和空间分布。现有的控制模型和方程不能考虑由于成形工艺引起的变化，例如合金成分、成形速度变化、温度等。作为示例性成形工艺，使用镁合金的双辊铸造，其中在成形之前在工艺区中进行初级成形工艺。由于铸嘴和铸辊之间存在自由表面，凝固区的位置和形状都是先验未知的，因此双辊铸轧是一个自由边值问题，是一个亚稳态问题。在过程控制方面，由于缺乏弹性测量数据，双辊铸造与所产生的材料性能的关系仅得到部分理解或评估。测量和模型的不确定性是由于缺乏测量数据，特别是在铸造过程中凝固范围的位置和形状。在本项目中，这些不确定性将被消除的一个新开发的传感器系统集成在辊。在整个材料的成型过程中，目前无法随时检测显微组织和最终带材性能。因此，并非所有的干扰因素都可以在模型中考虑。通过定量测量铸轧间隙中的应力状态以及温度和热流，消除了铸轧过程中基于性能的鲁棒控制的不确定性。必须开发强大的测量系统和软传感器，以允许在动态测量期间从可测量的量可靠地估计微观结构状况。该合作预计将导致有关弹性，微观结构和性能控制成形工艺设计的知识的根本增加。

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.