Three-dimensional Modeling of Plastic Transportation in a Single-screw Extruder - Joint Examination of Feed Zone and Melting Zone

单螺杆挤出机中塑料输送的三维建模 - 进料区和熔融区的联合检查

• 批准号: 324934383
• 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: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/324934383?language=en
• 关键词: Three; dimensional; Modeling; Plastic; Transportation

In plastics processing single-screw extruders are used to produce profiles, pipes, plates, films and many other products. The single-screw extruder is a continuously working production machine. Usually the optimization is focused on an increase of the throughput performance, while keeping the product quality on a high level. Previous investigations show that the throughput performance is limited on the one hand by feeding the extruder, on the other hand by the melting performance. At high rotational speed the screw is not able to draw in enough plastic particles from the hopper to fill the screw channels entirely. Simultaneously the inserted plastic particles have to be melted completely and homogeneously in the following melting zone to ensure a high product quality. Thereby, simulation approaches, especially three-dimensional models, essentially contribute to the under-standing of the transport phenomena in the feed and melting section of single-screw extruders. Until now, both sections had to be handled separately in the existing models due to the complex physical processes at their interface. However, an overall approach is absolutely necessary, because it is not effective to increase the throughput performance without considering the product quality. The aim of this research project is the integrated three-dimensional simulation of the feed and melting section by means of a single simulation environment. The discrete-element method is going to be used for the simulation of the solid particles transportation. Thus, the inserted plastic particles can be considered individually. The subsequently developing melt flow will be calculated with the help of the finite-volume method. The coupling of both phases, including phase transitions, will be realized in the open-source simulation environment CFDEM®coupling by means of a novel melting model, which will be established and implemented within the project for the first time. Moreover, a special experimental set-up is planned to be utilized to support the model development and validation. The general applicability will be shown by means of a study on a single screw extruder with both smooth and grooved feeding barrels. In addition to the obtained pressure and temperature data, dead-stop experiments will be performed to observe and evaluate the transition point as well as the melting behavior inside the extruder. Afterwards the feeding barrel and the screw will be optimized on the basis of the simulation results. The project is planned to be realized within an international D-A-CH-project. The cooperation consists of the research institutes Institut für Kunststofftechnik (University of Stuttgart, Germany) and CFDEMresearch (Linz, Austria). Within the cooperation, the competences of both research institutes will be pooled for the project.

在塑料加工中，单螺杆挤出机用于生产型材、管材、板材、薄膜和许多其他产品。单螺杆挤出机是一种连续工作的生产机。通常情况下，优化的重点是提高吞吐量性能，同时保持产品质量在高水平。以往的研究表明，挤出机的喂料和熔融性能一方面限制了挤出机的吞吐量性能，另一方面也限制了熔融性能。在高转速下，螺杆不能从料斗中吸入足够的塑料颗粒来完全填充螺杆通道。同时，插入的塑料颗粒必须在接下来的熔融区完全和均匀地熔化，以确保高产品质量。因此，模拟方法，特别是三维模型，对于理解单螺杆挤出机喂料和熔融段的输送现象具有重要意义。到目前为止，由于界面处的复杂物理过程，这两个部分在现有模型中必须分别处理。然而，一个整体的方法是绝对必要的，因为在不考虑产品质量的情况下提高吞吐量性能是不有效的。本研究项目的目的是通过单一的模拟环境对喂料和熔化部分进行一体化的三维模拟。采用离散单元法对固体颗粒的输运过程进行数值模拟。因此，插入的塑料颗粒可以单独考虑。随后发展的熔体流动将借助有限体积法进行计算。两个阶段的耦合，包括相变，将通过一个新的熔化模型在开源模拟环境CFDEM®耦合中实现，该模型将首次在项目中建立和实施。此外，还计划利用一种特殊的实验装置来支持模型的开发和验证。通过对具有光滑和凹槽喂料桶的单螺杆挤出机的研究，将显示其普遍适用性。除了获得压力和温度数据外，还将进行死止点实验，以观察和评估转换点以及挤出机内部的熔融行为。然后根据模拟结果对进料筒和螺杆进行优化。该项目计划在一个国际D-A-CH项目内实现。合作机构包括研究所(德国斯图加特大学)和CFDEMResearch(奥地利林茨)。在合作中，两个研究机构的能力将集中在该项目上。