NIR spectroscopy has become an analytical tool frequently used in many chemical production processes. Its use in polymer processing applications such as polymer extrusion would greatly increase product quality. Parameters of interest in this application are composition of the processed polymer, moisture or reaction status in reactive polymeric systems, as well as rheological parameters such as melt flow index (MFI) or viscosity. The measurement of NIR spectra could provide a way to control the processes. For this purpose a transmission sensor was developed for the application of NIR spectroscopy to extrusion processes.
This sensor includes fibre optical probes and a measuring cell that can be adapted to the various extruders for in-line measurements. In contrast to mid-infrared sensors, it uses optical quartz components, which provides a low-cost solution. Extrusion processes at temperatures up to 300°C and pressures up to 35 MPa have been investigated. The application of multivariate analysis for PE/PPblending demonstrated the performance of the system with respect to process monitoring. In this case deviations between predicted and actual polymer composition were below 2%. Together with an AOTF spectrometer that was also developed, the complete system is suitable for harsh industrial environments and could lead to improved extrusion processes.
Precision forging is a rather new special hot forming technology with a high economic potential. The lifetime of a forging tool is one of the most decisive factors during the economical evaluation of a forging and is therefore the subject of intensive investigation and research work. This paper shows results obtained in experimental work and theoretical analysis for the determination of tool wear. Observations have shown that the temperature of the raw material is of major importance for tool wear because of damaging effects on crystalline structure and in consequence mechanical properties of boundary layers of the forging tool. The example of temperature calculation which is strongly connected with heat exchange inside the tribological system explains the complex problems of the theoretical analysis. Additionally the heat transfer itself influences the geometry of the finished forged part, which is in the industrial case of major importance. The heat transfer during the different manufacturing stages has been analysed using the finite element method, which has been further developed to automatically determine the heat-transfer coefficient. Finally, a new method to calculate wear amounts at critical areas of forging tools is presented.
as measured by the focusing spectrometer of the NA44 experiment at CERN. Multidimensional ts are performed in order to characterize the kaon-emission volume, which is found to be smaller than the pion-emission volume.
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