Extrusion Asia Edition 1-2020

37 Extrusion Asia Edition 1/2020 图1:新开发的气流导向系统在挤出加工过程中：侧视图 Picture 1: Side view of the developed air-guiding system during the extrusion process IKV - Institute for Plastics Processing in Industry and Craft at RWTH Aachen University Lars Kraus, M.Sc., Blown film extrusion Seffenter Weg 201, 52074 Aachen, Germany lars.kraus@ikv.rwth-aachen.de www.ikv-colloquium.com, www.ikv-aachen.com constantly further developed and optimised. IKV has been oc- cupied for some years with the development of new cooling technologies in blown film extrusion. Examples include the use of moist air and a contact cooling sleeve. A highly promising new possibility to increase the cooling per- formance in blown film extrusion is the recently developed flexible and adaptive air-guiding system. This is installed downstream of a conventional air cooling ring. Through the use of a flexible membrane, it guides and speeds up the cooling air between the film bubble and the membrane, which leads to the formation of the Venturi effect. The Venturi effect increases the heat transfer of the cooling air and also provides increased bubble stability. For a successful process control, care must be taken to ensure that the flow gap between the air-guiding membrane and the film bubble is as small as possible. In order to be able to accurately observe the flow gap, the research team at IKV has designed a transparent air-guiding system. Ad- justment of the air-guiding membrane is carried out by means of pressure screws ( Picture 1 ). Current research results confirm the potential of the developed air-guiding system. The mass throughput with virtually identical film thickness fluctuations can be increased by up to 32 percent compared with the conventional process. Even the retrofitting of existing production machines is possible, and the required in- vestment is relatively small. 推力螺杆 thrust screw 空气导向薄膜 Air-guiding membrane 冷却空气 cooling air 流动间隙 flow gap 膜泡 film bubble www.smart-extrusion.com