Functionally integrative extruder concept with freely rotating screw sleeve and dynamic mixer to achieve high melt quality in high speed operation

通过提高螺杆速度可以实现挤出机性能提高的生产量增加。因此，高速工业应用的数量正在稳步增加。高速挤出仍然是一个令人感兴趣的研究领域，提高速度的关键是在保持高熔体质量的同时保持所需的熔体温度。然而，已知的是，规格产量随着速度的增加而降低，由此快速达到允许的材料温度。此外，材料的剪切力增加导致温度迅速上升。因此，高速挤出是通过高速S-Truder（HSST）等替代挤出技术来实现的。该概念基于固体和熔体的分离。它使用一个带有径向孔的自由旋转的螺杆套筒，以从快速旋转的螺杆的通道中移除熔体。使用动态混合环（DMR）进行均质化。使用HSST进行的塑化实验是积极的。尽管如此，已经证明了一些改进方法。特别地，在高速条件下使用动态混合器和熔体沿着螺杆套筒的不均匀移除抑制了可实现的速度和产量。因此，主要关注的是用于改进熔体移除和输送以及减少剪切加热的设计措施。如果能够解决上述问题，效率和功能将进一步提高。使用定制开发的材料模型进行熔融过程的CFD模拟，将对HSST中的塑化进行广泛的模拟和分析，以进一步了解该过程并制定优化措施。模拟用于设计合适的螺杆设计，以使螺杆套筒长度上的熔体去除均匀化，以及改进螺杆套筒设计。这主要包括进料区和螺杆套筒之间的长度比的修改。所使用的DMR是材料加热的主要原因，并适用于高速操作的条件。与上述操作并行的是，将开发用于S-Truder预设计的软件，该软件针对给定的螺杆和螺杆套筒设计计算HSST中发生的塑化和熔体流动，主要是分析。通过这种方式，在未来的工作中，复杂的数值计算流体动力学计算的数量可以减少到最低限度。将优化的HSST转化为实验室规模。进行塑化实验以确定其功能和性能，这意味着最大可实现的产量、温度发展和熔体质量。

The increase in throughput for a improved performance of extruders can be realized among others by increasing the screw speed. Accordingly, the number of high-speed industrial applications is steadily increasing. The high-speed extrusion is still an interesting field of research.Critical to the increase in speed is maintenance of the required melt temperature while keeping a high melt quality. It is known, however, that the spec. throughput decreases with increasing speed, whereby the permissible material temperature is reached quickly. Also the increasing shearing of the material causes a rapid rise in temperature. Therefore, the high-speed extrusion is enforced by alternative extrusion techniques such as the high-speed S-Truder (HSST).The concept is based on the separation of solid and melt. It uses a freely rotating screw sleeve with radial bores to remove the melt from the channel of the rapidly rotating screw. A Dynamic Mixing Ring (DMR) is used for homogenization.Plasticization experiments with the HSST were positive. Nevertheless, some improvement approaches have been demonstrated. In particular, the use of a dynamic mixer under high-speed conditions and uneven removal of the melt along the screw sleeve inhibit the achievable speeds and throughputs. Design measures for an improved melt removal and conveying as well as to reduce the shear heating are therefore of primary interest. If it is possible to solve the above mentioned problems, the efficiency and functionality could further increase.Using a custom developed material model for CFD simulation of melting processes extensive simulations and analysis of the plasticization in the HSST will be carried out to gain further understanding of the process and to develop optimization measures. The simulations are used to design a suitable screw design to homogenize the melt removal over the length of the screw sleeve as well as to improve of the screw sleeve design. This primarily includes a revision of the length ratio between the feed zone and the screw sleeve. The used DMR is a major cause of the heating of the material and is adapted to the conditions of the high-speed operation.Parallel to the above operations a software for the pre-design of the S-Truder will be developed which calculates the plasticizing and the melt flows occurring in the HSST for a given design of the screw and screw sleeve largely analytical. By this the number of complex, numerical CFD calculations can be reduced to a minimum in future works. The optimized HSST is transposed to a laboratory scale. Plasticization experiments are performed to determine its functionality and performance, this means the maximum achievable throughput, the temperature development and the melt quality.