With the developing of grinding technology to the high-speed, high-accuracy and heavy-cuts, the dynamic balancing in situ for grinding wheel and workpiece running at high speed has been paid more and more attention. Based upon the influence coefficient method, which widely used in industry for both rigid and flexible rotor balancing in situ, a new technique, called relative coefficient method, has been developed for rotor balancing. The steps for measuring the relative coefficients and the examples of rotor balancing with HP3562A are given in the paper. It has been proved that the method is more efficient, more readily computerized and automated. With the portable two-channel Dynamic Signal Analyzer (DSA), the relative coefficients can be measured directly and automatically in the field. Thus it will lead a fast and accurate technique for rotor balancing in the field. Introduction With the developing of grinding technology to the high-speed, high-accuracy and heavy-cuts, the dynamic balancing in suit for grinding wheel and workpiece at high speed has been paid more and more attention, and it is a key technique for improving the grinding quality and production efficiency. Therefore, it is important to develop balance methods which are fast, accuracy, easy to perform and applicable to many balancing problems. As well known, the two major used approaches to rotor balancing are the influence coefficient balancing and the modal balancing. The influence coefficient method has certain features, such as easy to use, readily computerized and automated [1]. It is, therefore, gained acceptance by engineers easily and becomes possibly the most widely used technique in industry today for in situ balancing. Since the influence coefficient method is entirely empirical, the key to the problem is how to generate the influence coefficients or influence vectors fast and accurately. L.J. Everett proposed a two-plane balancing technique without phase measurements [2]. W.C. Foiles and D.E. Bently developed a balancing technique with phase only [3]. In this paper, a relative coefficient method for rotor balancing is developed based on the influence coefficient method. The foundation and the mathematical presentation are described. It is shown how the relative coefficients can be generated with dual-channel (or multiple-channel) Dynamic Signal Analyzer directly. Thus, it will provide engineers with fast and accurate balancing technique, especially in field balancing. Influence Coefficient Method (ICM) The influence coefficient method for multiplane balancing will be briefly discussed here based upon the mechanical vibration analysis theory [2], since it is the basis of applying the influence coefficient method to rotor balancing correctly. Assuming that the rotor system is a linear lumped parameter system, we write the fundmental vibration matrix equation in the frequency domain, in which vibration component can be separated more effectively than in the time domain, as follow: Key Engineering Materials Online: 2004-03-15 ISSN: 1662-9795, Vols. 259-260, pp 751-755 doi:10.4028/www.scientific.net/KEM.259-260.751 © 2004 Trans Tech Publications Ltd, Switzerland All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications Ltd, www.scientific.net. (Semanticscholar.org-13/03/20,19:03:52) 752 Advances in Grinding and Abrasive Processes { } { } 0 , 1 ( 1) 1 1 p i ij j i m k n n m m k v h u h f + × × × = = + . (1) where vio: original vibration response at measuring station (i=1,2,
,n), as a function of frequency; hij : transfer function or frequency response function at station i due to excitation at station j (j=1,2,
,m); uj: original shaft unbalance at plane j, as a function of frequency; fk: the k th excitation force except origining from unbalance, such as oil and whirl in bearing etc., as a function of frequency (k=1,2,
,p). All terms mentioned above are complex numbers, or vectors. The vibration response at station i is: