Analyzing and modeling of short-time dynamic yarn handling processes through the example of high-performance warp knitting

在纺织工业中，近年来有两个主要的发展，其目的是增加产量、结构可变性和纺织品质量。第一个发展包括通过更高的机器速度和更大的工作宽度来提高纺织机器的性能，这导致纺织产品的生产更具成本效益。第二个发展涉及定制纺织品解决方案的生产（例如在汽车和FRP应用技术领域）。在这里，低允许误差数、高可重复性产品质量、低停机时间以及高质量纱线材料（如玻璃、碳、芳纶纤维和短纤维纱线）的可加工性是需要满足的要求。确定不同的纱线材料、工艺参数和导纱元件之间的相互作用和依赖关系对于显著的改进以及因此对于纱线运行的均匀化是至关重要的。此外，由于影响参数的数量以及机器特定参数和技术参数的复杂相互作用，这变得更加困难。因此，该项目的目的是通过高性能经编的例子，在非稳态操作中的短时间动态纱线处理过程的研究和建模。这种纺织品制造技术的特点是由于高加工速度而具有高纱线动态特性。这就产生了用于纱线运行过程的极短时间的动态应力场景，可以通过模拟和测量技术进行评估。这些动态应力情况包括，除其他外，横向加速度与所产生的横向和纵向振动，包括相关的阻尼现象。此外，还必须深入分析由不连续缝合过程以及由工作元件的叠加的运行速度相关的自然振荡引起的动态交变应力。这些影响对于纺织品制造过程的质量和稳定性至关重要。一个全面的，耦合模型是开发和验证的一个准确的描述复杂的机器和纱线动力学以及它们的相互作用。

In the textile industry, two major developments have been noted in recent years, which aim at increasing production quantities, structural variability and textile quality. The first development comprises the increase in performance of textile machines by higher machine speeds and greater working widths, which leads to a more cost-effective production of textile products. The second development concerns the production of tailored textile-based solutions (e.g. in the automotive and technical fields for FRP applications). Here, low permissible number of errors, high reproducible product quality, low machine downtime as well as the processability of high-quality yarn materials, like glass, carbon,aramid fibers and staple fiber yarns, are requirements to be met. The determination of interactions and dependencies between the different yarn materials, process parameters and yarn guide elements is essential for a significant improvement and thus for the homogenization of the yarn run. Moreover, this is made more difficult by the number of influencing parameters and the complex interaction of machine-specific and technological parameters. The aim of the project is therefore the research and modeling of short-time dynamic yarn handling processes in non-stationary operation through the example of high-performance warp knitting. This textile manufacturing technology is characterized by high yarn dynamics due to high processing speeds. This results in extremely short-time dynamic stress scenarios for the yarn running processes to be evaluated in terms of simulation and measurement technology. These dynamic stress scenarios comprise, amongst others, transverse accelerations with resulting transverse and longitudinal vibrations, including associated damping phenomena. In addition, dynamic alternating stresses caused by the discontinuous stitching process as well as by superimposed operating speed-dependent natural oscillations of the working elements have to be analyzed in-depth. These effects are of fundamental importance for the quality and stability of the textile manufacturing process. A comprehensive, coupled model is to be developed and validated for an accuratedescription of the complex machine and yarn dynamics as well as their interactions.