Grinding of riblets with "beaver tooth" multi-layer tools

To reduce friction in turbo machinery components, riblets are induced on compressor blades or pump impellers. Here, the grinding process enables a higher productivity in machining of riblet structures compared to knurling, laser or milling operations. Usually, profiled grinding tools are used to create such structures inspired by sharkskin. Unfortunately, conventional grinding tools have to be dressed continuously to keep the desired profile in the circumferential surface. To avoid the time-consuming dressing process and to enable a self-sharpening effect, an innovative multi-layer tool concept is developed. The tool consists of two types of thin polyimide layers. The first type contains abrasives and the second is a support layer without abrasives. These layers are piled alternately in a special manufacturing process and act like a monolithic tool in grinding process. The aim of the investigations presented in this paper is to find an optimal parameter setting to produce riblet structures productively by using the self-sharpening effect. The optimal setting allows a grinding process without any dressing process by using a large part of the grinding tool volume. At first, the manufacturing process is focused to create clearly divided support and abrasive layers of the grinding tool. Furthermore, the investigation shows the relationship between grinding parameters and the setback of the supporting layer in the middle of the tool. This setback is important for the creation of riblet structures in the surface of AISI 420 workpieces

Optimierung des Brandverhaltens von CFK-Werkstoffen durch Barriereschichten

In der Arbeit werden die Grundlagen zum Thema faserverstärkte Kunststoffe und deren Brandverhalten erläutert. In einer Literatur- und Patentrecherche werden Brandschutzmaterialien und –systeme in Natur und Technik beschrieben. Es werden die Auswahl und Verwendung verschiedener Barrierematerialien diskutiert. Im Hauptteil der Arbeit werden die verwendeten Barrierematerialien beschrieben und auf die Fertigung und Vorbereitung der Prüfkörper eingegangen. Anschließend wird die Durchführung und Auswertung von Dickenmessung, Ultraschall-, Durchbrand-, Restfestigkeits- und Smoke-Toxicity-Prüfung vorgenommen. Im letzten Abschnitt werden alle Materialien bezüglich ihrer Prüfergebnisse bewertet und Hinweise sowie Verbesserungsvorschläge für künftige Prüfungen gegeben

Prediction of Ground Surfaces by Using the Actual Tool Topography

This paper presents a prediction model for ground surfaces that uses the actual grinding wheel topography to perform a grinding simulation. Precise knowledge of expected machined surfaces plays an important role in process planning. Here, the main criterion is the achievement of the components’ function after manufacturing. Therefore, it is essential to consider the surface roughness to enable a function-orientated workpiece surface. The presented approach uses a real grinding tool topography, which is measured by a 3D laser triangulation sensor in the machine tool. After a data processing step, the measured topography is imported into a material removal simulation. A kinematic simulation of the realistic ground surface enables the data-based confirmation of the envelope profile theory for the first time