TransForm - Controlling the wrinkling of fibre-based materials through adaptive process control and camera-based data acquisition in transparent forming tools

法律框架条件和消费者对可持续包装日益增长的需求都要求减少以塑料为基础的一次性包装的份额。另一种替代方案是纸质纤维包装。为了能够提供种类繁多的形状，需要进行拉深等三维成形工艺。可实现的低成形度和出现的缺陷仍然对以纸为材料的塑料包装的全面替代构成挑战。深拉深纸的一个特别明显的缺陷是凸缘上形成的皱纹。这些主要是由于材料在成形过程中的位移引起的切向压应力造成的，但其确切的局部和时间的形成和发展还没有得到充分的了解。这一情况以及局部影响成形过程的方法的开发将在拟议项目的范围内加以处理。关键部件是透明模具和基于图像的传感器，用于现场检测进料和皱纹的形成。在此光学过程监测的基础上，可以在时间分辨率上深入了解局部材料流动的影响因素，并可以与皱纹形成的解析预测进行比较。在此基础上，研究了局部自适应过程控制。局部自适应过程控制对于复杂的成形几何形状和纤维材料纸的强烈各向异性材料特性特别有前景。为此，正在使用附加制造工艺开发一种局部自适应压边机。借助于可单独控制的弹性压腔，可以研究压边压力的局部自适应控制和调节对皱纹的影响。这样做的目的是最大限度地提高所生产零件的质量。

Both legal framework conditions and a growing consumer need for sustainable packaging require a reduction in the share of plastic-based disposable packaging. An alternative to this is paper-fibre-based packaging. In order to be able to offer a high variety of shapes, three-dimensional forming processes such as deep-drawing are required. The low degree of forming that can be achieved and the defects that occur still pose challenges for a comprehensive substitution of plastic-based packaging with paper as a material. A particularly noticeable defect in deep-drawing paper is the formation of wrinkles in the flange. These basically occur due to tangential compressive stresses as a result of material displacement in the forming process, but their exact local and temporal formation and development are not yet sufficiently understood. This circumstance as well as the development of methods to locally influence the forming process are to be addressed within the scope of the proposed project. The key elements are a transparent die and image-based sensors for the in-situ detection of the material feed and the formation of wrinkles. On the basis of this optical process monitoring, insights into influencing factors on the local material flow can be gained with temporal resolution and a comparison with an analytical prediction of the wrinkle formation can be carried out. On this basis, locally adaptive process control is investigated. Locally adaptive process control is particularly promising for complex forming geometries and due to the strongly anisotropic material properties of the fibre material paper. For this purpose, a locally adaptive blank holder is being developed using additive manufacturing processes. By means of individually controllable elastic pressure pockets, the influence of a locally adapted control and regulation of the blankholder pressure on the wrinkle pattern can be investigated. The aim is thus to maximise the quality of the produced part.