scholarly journals Computational and experimental analysis of machine tool vibrations in micro-milling

2017 ◽  
Vol 112 ◽  
pp. 01022 ◽  
Author(s):  
Dimitrios Sagris ◽  
Constantine Davids ◽  
Evlampia Stergianni ◽  
Christos Tsiafis ◽  
Ioannis Tsiafis
2021 ◽  
Vol 55 ◽  
pp. 568-575
Author(s):  
Michal Richtarik ◽  
Martin Gavlas ◽  
Mário Drbúl ◽  
Andrej Czán ◽  
Milan Sága
Keyword(s):  

Author(s):  
Amir Nankali ◽  
Young S. Lee ◽  
Tamás Kalmár-Nagy

We study the dynamics of targeted energy transfers in suppressing chatter instability in a single-degree-of-freedom (SDOF) machine tool system. The nonlinear regenerative (time-delayed) cutting force is a main source of machine tool vibrations (chatter). We introduce an ungrounded nonlinear energy sink (NES) coupled to the tool, by which energy transfers from the tool to the NES and efficient dissipation can be realized during chatter. Studying variations of a transition curve with respect to the NES parameters, we analytically show that the location of the Hopf bifurcation point is influenced only by the NES mass and damping coefficient. We demonstrate that application of a well-designed NES renders the subcritical limit cycle oscillations (LCOs) into supercritical ones, followed by Neimark–Sacker and saddle-node bifurcations, which help to increase the stability margin in machining. Numerical and asymptotic bifurcation analyses are performed and three suppression mechanisms are identified. The asymptotic stability analysis is performed to study the domains of attraction for these suppression mechanisms which exhibit good agreement with the bifurcations sets obtained from the numerical continuation methods. The results will help to design nonlinear energy sinks for passive control of regenerative instabilities in machining.


2018 ◽  
Vol 941 ◽  
pp. 2448-2453 ◽  
Author(s):  
Andrea Böhme ◽  
Felix Schütze ◽  
Sabine Sauer ◽  
Andreas H. Foitzik

Bioreactor systems for cultivating cells in Life Sciences have been widely used for decades. Recently, there is a trend towards miniaturization, disposables and even micro platforms that fulfill increasing demands strongly aiming for production and testing of novel pharmaceutical products. Miniaturized bioreactors allow low power consumption, portability and reduced space requirements and utilize smaller volumes of reagents and samples [1,2]. A recursive strategy is necessary for optimizing the design and the manufacture of such miniaturized bioreactors. For the fabrication of these prototypes utilized micro-milling. Micro milling is a mechanical process which is commonly applied to create micro-structures in metals, e.g. aluminum and steel, or polymers, e.g. poly carbonate substrates. The structures and geometries are generated by utilizing computer aided design. By means of computer-aided manufacturing, the machining operations are implemented and then transferred to the machine tool. The machine tool moves the cutting tools with certain speeds, feeds and traverse ranges to the substrate. Micro milling has the advantage that the materials are generally not degraded by chemical substances, heating procedures or electromagnetic radiation.


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