Πλοήγηση ανά Συγγραφέα "Friderikos, O."
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Τεκμήριο Experimental and computational investigation of end-milling and development of a simulation model describing the machining process(2011-08) David, C.; Antoniadis, A.; Friderikos, O.; Sagris, D.Modern requirements in manufacturing industry for mechanical products of better quality and higher accuracy machined by material removal, and the pursuit of minimization of the production costs, in conjunction with the growing complexity of the product geometry, led to further development of the computer numerically controlled (CNC) machine tools, and of the respective CAD/CAM systems. However not enough progress is occurred with emphasis on the development of computational systems, which can determine the most efficient cutting conditions, taking also into account the dynamic behavior of the machine tool system and the tool path planning. This paper is proposing an experimental-computational method in terms of appropriate simulation model, which allows the selection of optimum cutting conditions in end-milling processes, taking into consideration the workpiece surface quality, the developed cutting forces, the vibration deflections in the cutting zone, as well as the strategy of the tool path planning. Finally, the objective of the paper is to deliver an innovative methodology capable to be exploited in manufacturing industry with following benefits: • Increase of the material removal rate • Improvement of the workpiece surface • Increase of the cutting tool life • Restriction of faulty products • Reduction of costs and machining time with increase of productivityΤεκμήριο Investigation of shear instability in orthogonal machining of TI6AL4V alloy using the finite element method(2011-06) Friderikos, O.; Korlos, A.; David, C.; Tsiafis, I.During orthogonal cutting of Ti6Al4V alloy the chip is segmented, suggesting the emergence of some kind of instability during plastic deformation of the material. The segmented chip formation occurs from low cutting speeds and persists even at very high speeds, but with a notable change of the chip morphology. Considerable research efforts have been conducted worldwide to explain the underlying physical mechanisms of the segmented chip formation, and several theoretical models have been proposed. Theoretical models based on thermally aided shear instability which results to adiabatic shear bands formation proposed to explain the plastic instability of the material at high deformation rate s. Unfortunately, these models cannot provide answers at low deformation rates. On the other hand, fracture models which consider machining as a mechanism of ductile or brittle fracture explain the segmented chip formation as a periodic crack generation mechanism . Despite the above theoretical approaches, the phenomenon is still not well understood. The objective of this work is to investigate the mechanisms of catastrophic shear instability during orthogonal cutting of Ti6Al4V alloy based on coupled thermomechanical rigid viscoplastic finite element simulations in a wide range of cutting speeds