Chatter model for enabling a digital twin in machining
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ORIGINAL ARTICLE
Chatter model for enabling a digital twin in machining Shukri Afazov 1 & Daniele Scrimieri 2 Received: 15 April 2020 / Accepted: 1 September 2020 # The Author(s) 2020
Abstract This paper presents the development of a new chatter model using measured cutting forces instead of a mathematical model with empirical nature that describes them. The utilisation of measured cutting forces enables the prediction of real-time chatter conditions and stable machining. The chatter model is validated using fast Fourier transform (FFT) analyses for detection of chatter. The key contribution of the developed chatter model is that it can be incorporated in digital twins for process monitoring and control in order to achieve greater material removal rates and improved surface quality in future industrial applications involving machining processes. Keywords Digital twin . Chatter model . Cutting forces
1 Introduction Chatter modelling in machining dates from the 1960s when Tlusty and Polacek [1] and Tobias [2] presented chatter models in machining. Later, Altintas and Budak [3] developed a chatter model with dynamic uncut chip thickness by solving the equation of motion analytically in the frequency domain. Further chatter models considering velocity-dependent damping and cutting forces, as well as run-out effects, have been solved in the time domain using numerical integration [4]. The challenge in all developed chatter models is that the cutting force model needs to accurately predict the actual cutting forces which depend not just on the cutting parameters but also on the cutting tool geometry, frictional conditions, kinematics of the cutting tool and workpiece material state [5]. For instance, the geometry of the cutting edge changes due to wear and the frictional conditions can change too. The workpiece material might have different properties in different locations due to differences in the material microstructure. All
* Shukri Afazov [email protected] 1
Department of Engineering, School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, UK
2
Department of Computer Science, University of Bradford, Bradford BD7 1DP, UK
these factors introduce uncertainties for the accurate prediction of the cutting forces and create challenges in using existing chatter models in process monitoring and control. The use of process damping at low spindle speeds has been widely used in the past as well as the design of machine tools with enhanced damping capabilities [6]. Chatter avoidance has been approached by structural modification of tool-holder geometry in order to change the structural dynamics as well as tuning the mass of the tool-holder assembly [7]. Measured cutting forces, accelerations and acoustic emissions have been widely used for process monitoring and control. The most widely used methods are the conversion of measured signals from the time domain into the frequency domain for detection of chatter [8]. Other researchers used the root mean square value in the time domain to ide
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