Calculation of the pellet transportation in grooved feed zones, considering varying conveying mechanisms at high screw speeds

考虑高螺杆速度下不同的输送机制，计算沟槽进料区域中的颗粒输送

• 批准号: 423276016
• 负责人: Professor Dr.-Ing. Christian Bonten
• 金额: --
• 依托单位: Institut für Kunststofftechnik (IKT)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/423276016?language=en
• 关键词: Calculation; pellet; transportation; grooved; feed

Single-screw extrusion is an important production process for large-scale plastic product manufacturing at low cost. In recent year, so-called high-speed extruders have gained momentum. These systems operate at screw speeds a lot higher than for conventional processes and thus generate a higher output and productivity. Especially for mass-production industries like blow film or others, the combination of such high outputs at small extruder sizes is very promising. Therefore, many current research activities focus on the optimization and applicability of these systems. However, conventional approaches for screw and barrel design cannot longer be used, as the baseline assumptions for the throughput calculations are not valid for high screw speeds. Therefore, new or optimized methods are required.Especially the phenomenon of a decreasing specific throughput at higher screw speeds has to be considered. As this problem has been well known for decades, a variety of constructive counter measure were developed in the past. However, these solutions still have their limits at such high screw speeds, which is why the phenomen has to be integrated in the mathematical description of the conveying mechanisms. The throughput calculation for conventional extruders is usually based on the axial conveying speed, the free intersection of the screw channel and the bulk density of plastic pellets. This leads to a linear correlation between screw-speed and throughput, which cannot be held up for high-speed extruders. There are approaches to make corrections in order to consider the decreasing specific throughput, however, they all require a statistical calibration of heuristic correction factors, which different authors have obtained by performing experiments or simulations, which limits the applicability to the tested materials.Therefore, the objective of this project is to expand and enhance throughput calculation models based on actual and measureable values of the screw and barrel design and the pellet characteristics. Other than former approaches, no statistical or heuristic factors shall be used. Also, physically plausible effects like the occurring centrifugal forces will be considered.

单螺杆挤出是大规模低成本生产塑料制品的重要生产工艺。近年来，所谓的高速挤出机获得了发展势头。这些系统以比传统工艺高得多的螺杆速度运行，从而产生更高的产量和生产率。特别是对于像吹塑薄膜或其他大规模生产行业来说，在小型挤出机上结合如此高的产量是非常有希望的。因此，当前的许多研究活动都集中在这些系统的优化和适用性上。然而，螺杆和机筒设计的传统方法不能再使用，因为吞吐量计算的基线假设在高螺杆速度时不适用。因此，需要新的或优化的方法，特别是在螺杆转速较高时，必须考虑比吞吐量下降的现象。由于这一问题几十年来一直广为人知，过去制定了各种建设性的对策。然而，在如此高的螺杆转速下，这些解决方案仍然有其局限性，这就是为什么必须在输送机构的数学描述中集成这些现象。常规挤出机的吞吐量计算通常基于轴向输送速度、螺杆通道的自由相交和塑料颗粒的堆积密度。这导致了螺杆转速和吞吐量之间的线性关系，这在高速挤出机中是无法维持的。为了考虑比吞吐量的下降，有一些修正方法，但它们都需要对不同作者通过实验或模拟获得的启发式修正因子进行统计校准，这限制了对被测材料的适用性。因此，本项目的目标是基于螺杆和机筒设计的实际值和颗粒特性的可测量值来扩展和增强吞吐量计算模型。除以前的方法外，不得使用统计或启发式因素。此外，还将考虑物理上合理的影响，如发生的离心力。