Holistic optimisation of sculptured surfaces manufacturing
Final Report Abstract
The aim of the works conducted in the report period was to use and extend existing and to develop new monitoring systems and simulation models, with the purpose to support the development of an adaptive system, which can be used to holistically optimize the milling of sculptured surfaces. As yet there had been no approach for a holistic optimization of sculptured surface manufacturing, respectively machining, considering the error development beginning with the design phase, continuing in the machining process and ending in the part inspection before the start of this project. Thus, the main approach was to develop and evaluate the capability of a holistic virtual machine tool, which also would be acting as knowledge database. Therefore, experimental, analytical and numerical research has been done in the scope of the particular phases of manufacturing sequence. The Brazilian-German cooperation was very helpful regarding bringing together the competencies necessary to handle this complex topic. To identify and quantify the decisive factors which significantly influence the productivity and the work piece quality, different impact factor have been analyzed and contrasted. The focus thereby lied on error sources which are comparatively easy to measure, or to simulate using monitoring data. Furthermore, it was possible to separately examine the error sources and their impact. Scaling effects of the specific cutting force kc and its logarithmic slope mc could be confirmed. Independently of the process parameter, machining with ball nose milling tools implies very low chip thickness. The cutting force model in combination with the chipping model integrated in the virtual machine tool developed in this project is capable of predicting cutting forces in machining of sculptured surface. Also stable and instable processes could be determined appropriately. Monitoring sound emission for local tool wear determination is not applicable. While sound and acoustic emission can be successfully applied to detect tool failure, no significant correlation could be found between local radial tool wear, which is important to recognize the impact of tool wear on the machining accuracy. Various models have been developed and compared to describe the dynamic behaviour of the machine tool. To reflect the dynamic behaviour at the TCP in the time domain simulation, the p-LSCF method showed the best agreement between measurement and simulation. An algorithm has been developed to automatically identify the poles and zeros of the MDOF system by clustering with regard to information derived from stabilisation plots and applying a MQI. Simulated and measured FRF are in very good agreement. As presented in this report, a virtual machine tool comprising the different manufacturing phases CAD/CAM, machining and quality determination was developed. Various models have been developed enabling for an accurate simulation of 5-axis machining processes. Although the models showed deviations between simulation and experiments, the compensation of the errors involved in the analysis can improve the work piece quality significantly. The distinguished analysis of error proportions and propagations helped to identify optimization potential in the diversified cutting situations when machining sculptured surfaces.
Publications
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Holistic Optimisation of Sculptured Surface Manufacturing. Proceedings of COBEM 2011, Brazil, 2011
Schützer, K.; Uhlmann, E.; del Conte, E.; Mewis, J.
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Analyse der Konturabweichung beim Fräsen von Freiformflächen mit Hilfe Monitoring-gestützter virtueller Bearbeitung. In: Uhlmann, E. (Hrsg.): Tagungsband zur 7. Berliner Runde - Neue Konzepte für Werkzeugmaschinen, Berlin, March 2012, Fraunhofer IPK, Berlin, 2012, pp 193 - 207
Mewis, J.; del Conte, E.; Kaldonek, M.
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Analyse und Optimierung von Werkzeugmaschinen und Fertigungsprozessen. In: Zeitschrift für wirtschaftlichen Fabrikbetrieb (ZWF) 107 (7-8), 2012, pp 541 - 545
Uhlmann, E.; Bochnig, H.; Hu, J.; Ivanov, I.; Meister, F.; Mewis, J.; Prasol, L.; Rasper, P.; Richarz, S.; Ziefle, A.
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Improvement of surface accuracy and shop floor feed rate smoothing through open CNC monitoring system and cutting simulation. Fifth CIRP Conference on High Performance Cutting 2012, Procedia CIRP, Vol. 1, Zürich, 2012, pp 90 - 95
Schützer, K.; Uhlmann, E.; Del Conte, E.; Mewis, J.
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Simulation and analysis of error impact on freeform surface milling. The International Journal of Advanced Manufacturing Technology, Vol. 70, Issue 1 - 4, 2014, pp 607 - 620
Uhlmann, E.; Abackerli, A. J.; Schützer, K.; Lepikson, H. A.; Helleno, A. L.; Papa, M. C. O.; del Conte, E. G.; Mewis, J.
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Simulation und Analyse des Freiformfräsens. wt Werkstattstechnik Online, 104 (2014) 1/2, pp 27 - 32
Uhlmann, E.; Abackerli, A. J.; Schützer, K.; Helleno, A. L.; Papa, M. C. O.; del Conte, E. G.; Mewis, J.
