Papers by Keyword: Spindle Speed Variation

Abstract: This paper investigates the regenerative chatter in a plunge grinding process. The effect of the contact force on the onset of chatter vibration is clarified by a proposed continuation algorithm, and the boundary for the chatter-free region in which the grinding process is stable is obtained. By varying the rotational speed of the workpiece continuously, the chatter vibration with the values of the system parameters being near the boundary is suppressed, namely, the chatter-free region is expanded by this spindle speed variation control strategy.

Abstract: From the view of implementation and machine protection, this paper presents a novel scheme of programming spindle-speed variation for regenerative chatter suppression. It is based on the research of the necessary conditions of chatter, from a new perspective. Through standard test method, research are carried on the influence of the interval time and the speed variation amplitude on vibration suppression effectiveness. In this work, cutting process keeps relatively more stable without motor continuous overload, which is verified by theoretical analysis and experiments.

Abstract: In this paper the chatter stability of turning and full-immersion milling operations with spindle speed variation is studied. We present a method to calculate the stability lobes in the limit of very low and very high frequencies of the delay modulation. These approximations help to classify the results of numerically exact methods, as for example semi-discretization or multi-frequency approaches. For slowly time-varying delay, the position of the stability lobes is understandable from a simple connection between the lobes for constant and time-varying delay. Furthermore, this method can be used to estimate the efficiency of an application of spindle speed variation and helps to find optimal parameters for it.

Abstract: High-speed milling operations are often limited by regenerative vibrations. The aim of this paper is to analyze the effect of spindle speed variation on machine tool chatter in high-speed milling. The stability analysis of triangular and sinusoidal shape variations is made numerically with the semi-discretization method. Parametric studies show also the influence of the frequency and amplitude variation parameters. This modeling is validated experimentally by variable spindle speed cutting tests with a triangular shape. Stable and unstable tests are analyzed in term of amplitude vibration and surface roughness degradation. This work reveals that stability must be considered at period variation scale. It is also shown that spindle speed variation can be efficiently used to suppress chatter in the flip lobe area.

Abstract: Spindle speed variation (SSV) is one of a number of promising strategies to suppress chatter. Most previous research on SSV stability analysis for nonintermittent machining processes has focused on stationary-bar boring or turning. However, nonintermittent rotating-tool machining is also a common process. This paper investigates the effect of SSV in nonintermittent rotating-tool machining, using rotating-bar boring as an example. This paper takes advantage of the rotating-frame approach and the resulting constant delay in the angle domain to investigate the SSV effect on system stability for rotating-bar boring. The results show that the SSV effect on rotating-bar boring flattens the stability lobes and lifts the tangential stability limits.