Global Optimization and Design of Dynamic Absorbers for Chatter Suppression in Milling Process with Tool Wear and Process Damping

Abstract

Peripheral milling is extensively used in manufacturing processes, especially in aerospace industries where end mills are used for milling of wing parts and engine components. The generation of complex shapes with high quality for various types of materials is the main advantage of milling in contrast to other machining processes. During the milling process, the occurrence of self-excited vibrations or chatter may cause reduction in material removal rate (MRR), damage to the tool and spindle bearing or may result in poor dimensional accuracy and surface finish of the work-piece. In this paper, milling process is modeled as two degrees of freedom (2DOF) system in which the tool wear and process damping effects are considered. To suppress regenerative chatter (or self-excited vibrations), optimum tunable vibration absorbers (in x-y directions) are designed. A sophisticated optimization algorithm is developed to determine the optimum values of the absorber parameters (their mass and stiffness). The effects of tool wear, process damping and absorbers are investigated on the frequency response of the system. Results are presented in the time and frequency domains. According to the results, both of the tool wear and process damping play as stabilizing factors of the dynamic system; under regenerative chatter and unstable machining conditions. However, tuned vibration absorbers are implemented to achieve the global stable conditions. The robustness and efficiency of deigned absorbers are investigated for the uncertain dynamic model. It is shown that after implementation of the absorbers, higher material removal rate (MRR) can be achieved while the stability of the nominal and uncertain processes is guaranteed.

Numerical Analysis of Translational Vibration Reduction Response on Drilling Process due to Additional Mass-Rubber Dynamic Vibration Absorber (MR-DVA)

“…The results were obtained from the difference between the operating frequency and the chatter frequency in the drilling process, which is the chatter found within the observable frequency at 1,100 Hz. A Matlab simulation was carried out to test DVA on a 2 DoF milling machine [13]. The reduced vibration is directly proportional to the stability of the tool blade movement, making the milling results smoother, and the machine efficiency increases with the increase in the depth of cut of the machine.…”

H-infinity optimised control of external inertial actuators for higher precision robotic machining

“…While classic damping systems are effective only around a narrow frequency band, modern semi-active (Sun et al 2014(Sun et al , 2018 and active (Cowley and Boyle 1969;Sims 2007, 2008) damping systems, according to the terminology used (Brecher, Bäumler, and Brockmann 2013), have the capability of tracking and adapting to vibration frequency bands. Damping systems have proved to be effective for vibration absorption over a wide range of applications in conventional machining systems (Moradi, Bakhtiari-Nejad, and Movahhedy 2008;Díaz-Tena et al 2013;Saadabad, Moradi, and Vossoughi 2014;Scheidler and Dapino 2014) as well as in aerospace (Hiemenz, Hu, and Wereley 2008), automotive (Sapiński and Rosół 2008) and marine (Huang, Su, and Hua 2018) manufacture. However, damping systems are rarely used for vibration absorption in robot machining systems, though a magnetorheological elastomer-based semi-active damping system to suppress chatter frequencies ranging from 7 to 20 Hz in robotic milling has been developed (Yuan et al 2019).…”