Title: Study of tool dynamics with a discrete model of workpiece in orthogonal turning

Authors: K. Rama Kotaiah, J. Srinivas

Addresses: Department of Industrial and Production Engineering, K.L. University, Vaddeswaram (Post), Tadepalli (Mandal), Guntur (Dist)-522 502, India. ' Department of Mechanical Engineering, National Institute of Technology, Rourkela, Orrissa-769 008, India

Abstract: This paper proposes a realistic analytical stability model of regenerative chatter in orthogonal turning operation. Tool geometry is initially developed as a solid model and analysed at different tool overhang conditions. In each case, stiffness, fundamental bending mode and corresponding damping ratios of the tool are evaluated. With this data, cutting tool can be represented with a lumped parameter single-degree of freedom vibration oscillator. Workpiece dynamics on the other hand is considered independently using a discrete finite element beam model. At some contact node of the workpiece, tool mass imposes a regenerative cutting force and second order dynamic delay differential equations are formulated in terms of tool and modal parameters. Stability criterion is formulated from characteristic equation. The effects of tool-overhang and work cross-section on the stability from the proposed model are reported. Results are illustrated with a commonly used HSS cutting tool with tailstock-supported workpiece. Experimental analysis is carried out to show the effect of tool-overhang on cutting dynamics.

Keywords: tool overhang; finite element analysis; FEA; regenerative chatter; workpiece dynamics; stability; vibration; tool dynamics; discrete modelling; orthogonal turning; stiffness; bending; damping ratios; beam models; cutting force; cutting dynamics; HSS cutting tools; high speed steel.

DOI: 10.1504/IJMMM.2011.040855

International Journal of Machining and Machinability of Materials, 2011 Vol.10 No.1/2, pp.71 - 85

Published online: 30 Dec 2014 *

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