JOURNAL OF SOUND AND VIBRATION Journal of Sound and Vibration 297 (2006) 649–663 Experimental simulation of the sharpening process of a disc blade and analysis of its dynamic response C. Carmignani, P. Forte à , E. Rustighi 1 University of Pisa, Department of Mechanical, Nuclear and Production Engineering, via Diotisalvi 2, 56126 Pisa, Italy Received 7 October 2004; received in revised form 10 April 2006; accepted 12 April 2006 Available online 21 June 2006 Abstract The vibrations arising in the sharpening of large disc blades used in paper roll cutting machines are a crucial problem for paper manufacturing quality. In this work the results of an experimental investigation carried out on a reduced scale versatile test rig are presented and discussed. A series of tests were carried out varying the characteristic parameters of the process such as the grinding contact force, the contact friction, the grinding wheel and blade relative positions, and the sharpening time length. The Fourier transform was applied to the disc displacement signals and analyses of the waterfall plots obtained for the different cases show the influence of the operation and design parameters on the system dynamic behaviour. r 2006 Elsevier Ltd. All rights reserved. 1. Introduction Vibrations arising during the sharpening process of disc blades are a crucial problem in paper manufacturing. In particular, since paper rolls are cut by disc blades, defects in the blade edge caused by vibrations in sharpening, though small, can cause remarkable quality and productivity losses. Common practice has shown that in some cases the disc edge exhibits a periodic thickness irregularity caused by such vibrations. In the technical literature no specific work is reported but similar problems such as those related to grinding [1], saw blades, turbine rotors, computer magnetic recording discs [2,3] and brake discs [4–6] are dealt with. The problems mainly concern the response of a rotating disc to an external transverse force. It is well established [7–12] that a rotating disc, with respect to an inertial frame, displays a response that can be viewed as the superposition of a forward travelling wave motion and a backward travelling wave motion. With increasing disc rotational speed the frequency associated with the backward travelling wave approaches zero and a divergence instability arises, led by a transverse load applied to the rotating disc. The disc rotational speed at which this happens is identified as a critical speed [13]. ARTICLE IN PRESS www.elsevier.com/locate/jsvi 0022-460X/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.jsv.2006.04.018 à Corresponding author. E-mail addresses: carmi@ing.unipi.it (C. Carmignani), p.forte@ing.unipi.it (P. Forte), er@isvr.soton.ac.uk (E. Rustighi). 1 Present Address: University of Southampton, Institute of Sound and Vibration Research, Southampton SO17 1BJ, UK.