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

为了提高挤出机的性能，可以通过提高螺杆速度来实现产量的增加。因此，高速工业应用的数量正在稳步增加。高速挤压仍然是一个有趣的研究领域。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，众所周知，规格吞吐量随着速度的增加而降低，从而迅速达到允许的材料温度。同时，材料的剪切作用也会导致温度的迅速升高。因此，高速挤压是由替代挤压技术，如高速S-Truder （HSST）。这个概念是基于固体和熔体的分离。它使用一个自由旋转的带径向孔的螺杆套筒，从快速旋转的螺杆的通道中除去熔体。采用动态混合环（DMR）进行均匀化。HSST塑化实验呈阳性。然而，已经证明了一些改进方法。特别是，在高速条件下使用动态混合器和沿螺杆套不均匀地去除熔体抑制了可实现的速度和吞吐量。因此，改善熔体去除和输送以及减少剪切加热的设计措施是主要的兴趣。如果能够解决上述问题，则可以进一步提高效率和功能。使用定制开发的材料模型用于CFD模拟熔融过程，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。利用模拟结果设计了合适的螺杆设计，使螺杆长度上的熔体去除均匀化，并对螺杆设计进行了改进。这主要包括修正进给区和螺杆套之间的长度比。使用的DMR是材料发热的主要原因，适应高速运行的条件。与上述操作并行，将开发用于s - trude预设计的软件，用于计算给定螺杆和螺套设计的HSST中发生的塑化和熔体流动，主要用于分析。这样，在今后的工作中，可以将复杂的CFD数值计算的数量减少到最低限度。将优化后的HSST转置到实验室规模。进行塑化实验以确定其功能和性能，这意味着可实现的最大吞吐量，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.