Abstract

YANEZ-VALDEZ, R.; TELLEZ-GALVAN, J. A.; LOPEZ-PARRA, M.  and  URBIOLA-SOTO, L.. Dynamic stability of a parallel kinematic machine. J. appl. res. technol [online]. 2022, vol.20, n.1, pp.1-16.  Epub May 30, 2022. ISSN 2448-6736.  https://doi.org/10.22201/icat.24486736e.2022.20.1.1278.

Machine tool chatter causes machining instability, surface roughness, and tool wear in metal cutting processes. According to the different chatter mechanisms, chatter can be categorized into regenerative chatter, mode coupling chatter, frictional chatter, and force-thermal chatter. Both mode coupling chatter and regenerative chatter may occur during the machining process, depending on the specific machinery and machining condition. The regenerative chatter happens locally at workpieces or cutting tools. The mode coupling chatter happens globally, including the entire configuration. This article extends chatter stability analysis to a decoupled parallel kinematic machine (PKM). The vibration model of the PKM focuses on the regenerative chatter while the decoupled design of the machine is proposed to eliminate any occurrence of mode coupling chatter. Thus, the features that make it suitable for machining tasks are highlighted. A stability lobe diagram based on the theory of regenerative vibration is an effective tool to predict chatter. The vibration model of the PKM is derived in which the dynamic behaviour of the spindle/holder/tool system is considered. Then, the regenerative cutting dynamics is combined with the vibration model and stability analysis is performed. A step-by-step procedure provides a stability lobe diagram. The chatter stability charts for various machining parameters are examined, with the example of the decoupled PKM that is specially designed for machine tool use.

Keywords : Chatter; cutting force; parallel kinematic machine; parallel mechanism; stability lobe diagram.

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