Effects of bearing clearance on the chatter stability of milling process

Abstract

Abstract:In the present study, the influences of the bearing clearance, which is a common fault for machines, to the chatter stability of milling process are examined by using numerical simulation method. The results reveal that the presence of bearing clearance could make the milling process easier to enter the status of chatter instability and can shift the chatter frequency. In addition, the spectra analysis to vibration signals obtained under the instable milling processes show that the presence of bearing clearance could introduce more frequency components to the vibration responses but, however, under both the stable and instable milling processes, the generated frequency components will not violate the ideal spectra structures of the vibration responses of the milling process, which are usually characterized by the tooth passing frequency and its associated higher harmonics for the stable milling process and by the complex coupling of the tooth passing frequency and the chatter frequency for the instable milling process. This implies that, even under the case with bearing clearance fault, the stability of the milling process can still be determined by viewing the frequency spectra of the vibration responses. Moreover, the phenomena of the chatter frequency shift and the generation of more components provide potential ways to detect the bearing clearance in machines.

Free Vibration Analysis of Spinning Spindles: A Calibrated Dynamic Stiffness Matrix Method

“…The solution of the differential equation is sought in the form W = e rξ , and when substituted into (15), leads to…”

“…The modes of the machines structure determine the frequency and the direction that the tool is going to vibrate at [11]. Rather than the previously used machine design philosophy of "where there's vibration, add mass", it was then stated that designers must investigate the modeforms, weak points, bearing clearances, and self-inducing vibratory components of their machine design to try to reduce chatter [8,15]. Certain researchers even further investigatedthe required number of structural modes to produce accurate results [6].…”

Dynamic Modelling and Machining Stability in a New Mill-Spindle Design for Drilling Machine

“…The relationship between preload and spindle speed on the tested spindle is provided. Penga et al [8] used a discontinuous stiffness model to represent the effects of bearing clearance, the influence of the bearing clearance to the chatter stability of milling process have been examined though numerical simulation method. E. Solis et al [9] implemented a new chatter's analytical prediction method was combined with experimental multi degree-of-freedom systems modal analysis to achieve the objective of generating a new method to obtain the stability lobes information for some vibration modes that can be used to graph the stability lobes for high-speed milling, and these to help in the selection of parameters for chatter free operations.…”

On the Free Vibration Modeling of Spindle Systems: A Calibrated Dynamic Stiffness Matrix

“…The structural modes of the machine determine the frequency and the direction that the tool is going to vibrate at [7]. Eisele [5] and Peng et al [8] stressed that designers must investigate the mode-shapes, weak points, bearing clearances, and self-inducing vibratory components of the machine to reduce chatter. Butlin and Woodhouse also investigated the number of structural modes required to produce accurate results [9].…”