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基于塑料的一次性包装的份额。另一种选择是基于纸纤维的包装。为了能够提供各种各样的形状，需要三维成形工艺，如深拉深。可实现的低成形程度和发生的缺陷仍然对以纸为材料的塑料基包装的全面替代构成挑战。深拉伸纸的一个特别明显的缺陷是在凸缘处形成褶皱。这些基本上是由于形成过程中材料位移引起的切向压应力而发生的，但它们的确切局部和时间形成和发展尚未充分了解。这种情况以及在当地影响成形过程的方法的发展将在拟议项目的范围内加以解决。关键元件是一个透明的模具和基于图像的传感器，用于原位检测材料的进料和褶皱的形成。在这种光学过程监测的基础上，可以通过时间分辨率深入了解局部物质流动的影响因素，并可以与皱纹形成的分析预测进行比较。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特别适用于复杂的成形几何形状和由于纤维材料纸的强各向异性的材料特性。为此，正在使用增材制造工艺开发一种局部自适应压边机。通过单独可控的弹性压力袋，可以研究局部适应的压边压力控制和调节对起皱图案的影响。因此，目标是最大限度地提高生产部件的质量。

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.