1、BS ISO 21940-11:2016Mechanical vibration RotorbalancingPart 11: Procedures and tolerances forrotors with rigid behaviourBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 21940-11:2016 BRITISH STANDARDNational forewordThis British Standard is the UK implementatio
2、n of ISO21940-11:2016. It supersedes BS ISO 1940-1:2003 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee GME/21/5, Mechanical vibration, shock and conditionmonitoring - Vibration of machines.A list of organizations represented on this committee can beobt
3、ained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2016. Published by BSI Standards Limited 2016ISBN 978 0 580 84384 6ICS 21.120.40Compliance wit
4、h a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 30 November 2016.Amendments/Corrigenda issued since publicationDate Text affectedBS ISO 21940-11:2016 ISO 2016Mechanical vibratio
5、n Rotor balancing Part 11: Procedures and tolerances for rotors with rigid behaviourVibrations mcaniques quilibrage des rotors Partie 11: Modes opratoires et tolrances pour rotors comportement rigideINTERNATIONAL STANDARDISO21940-11First edition2016-11-15Reference numberISO 21940-11:2016(E)BS ISO 21
6、940-11:2016ISO 21940-11:2016(E)ii ISO 2016 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, inc
7、luding photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel
8、. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 21940-11:2016ISO 21940-11:2016(E)Foreword vIntroduction vi1 Scope . 12 Normative references 13 Terms and definitions . 14 Pertinent aspects of balancing . 14.1 General . 14.2 Representation of the unbalance 14.3 Unbalance effect
9、s 24.4 Reference planes for unbalance tolerances 24.5 Correction planes 44.5.1 General 44.5.2 Rotors which need one correction plane only 44.5.3 Rotors which need two correction planes . 44.5.4 Rotors with more than two correction planes . 44.6 Permissible residual unbalance . 45 Similarity consider
10、ations 55.1 General . 55.2 Permissible residual unbalance and rotor mass 55.3 Permissible residual specific unbalance and service speed 66 Specification of unbalance tolerances 66.1 General . 66.2 Derivation of the unbalance tolerances . 66.3 Balance quality grade G . 76.3.1 Classification . 76.3.2
11、Special designs . 76.3.3 Permissible residual unbalance . 106.4 Experimental evaluation . 106.5 Unbalance tolerances based on bearing forces or vibrations 106.5.1 Bearing forces 106.5.2 Vibrations 116.6 Methods based on established experience 117 Allocation of permissible residual unbalance to toler
12、ance planes .117.1 Single plane . 117.2 Two planes . 117.2.1 General. 117.2.2 Limitations for inboard rotors 127.2.3 Limitations for outboard rotors . 128 Allocation of unbalance tolerances to correction planes 138.1 General 138.2 Single plane . 148.3 Two planes . 149 Assembled rotors 149.1 General
13、149.2 Balanced as a unit 149.3 Balanced on component level . 1410 Accounting for errors in the verification of permissible residual unbalances .1510.1 General 1510.2 Unbalance tolerance 1510.3 Combined error of unbalance measurements 15 ISO 2016 All rights reserved iiiContents PageBS ISO 21940-11:20
14、16ISO 21940-11:2016(E)10.4 Verification of the permissible residual unbalance 1510.4.1 General. 1510.4.2 Unbalance readings within tolerance .1610.4.3 Unbalance readings out of tolerance .1610.4.4 Region of uncertainly 16Annex A (informative) Example of the specification of permissible residual unba
15、lance based on balance quality grade G and allocation to the tolerance planes.17Annex B (informative) Specification of unbalance tolerances based on bearing force limits .21Annex C (informative) Specification of unbalance tolerances based on established experience 23Annex D (informative) Rules for a
16、llocating unbalance tolerances from tolerance planes to correction planes 25Bibliography .28iv ISO 2016 All rights reservedBS ISO 21940-11:2016ISO 21940-11:2016(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodie
17、s). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and n
18、on-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are descr
19、ibed in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to
20、 the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the I
21、SO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as
22、 well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.The committee responsible for this document is ISO/TC 108, Mechanical vibration, shock and condition monitoring, Su
23、bcommittee SC 2, Measurement and evaluation of mechanical vibration and shock as applied to machines, vehicles and structures.This first edition cancels and replaces ISO 1940-1:2003, which has been technically revised. The main changes are deletion of the terms and definitions which were transferred
24、 to ISO 21940-2 and a more pronounced explanation of the application of permissible residual unbalances for the processes of balancing a rotor and verifying its residual unbalance. Information on specification of unbalance tolerances based on vibration limits has been removed.It also incorporates th
25、e Technical Corrigendum ISO 1940-1:2003/Cor 1:2005.A list of parts in the ISO 21940 series can be found on the ISO website. ISO 2016 All rights reserved vBS ISO 21940-11:2016ISO 21940-11:2016(E)IntroductionRotor balancing is a procedure by which the mass distribution of a rotor (or part or module) i
26、s checked and, if necessary, adjusted to ensure the unbalance tolerance is met. This document covers the balancing of rotors with rigid behaviour. A rotor is said to be rigid when the flexure of the rotor caused by its unbalance distribution can be neglected with respect to the agreed unbalance tole
27、rance at any speed up to the maximum service speed. For these rotors, the resultant unbalance, and often moment unbalance, are of interest, which when combined are expressed as a dynamic unbalance of the rotor.The balancing machines available today enable residual unbalances to be reduced to very lo
28、w limits. Therefore, it is necessary to specify an unbalance quality requirement for a balancing task, as in most cases it would not be cost-effective to reduce the unbalance to the limits of the balancing machine.In addition to specifying an unbalance tolerance, it is necessary to consider the erro
29、rs introduced by the balancing process. This document takes into account the influence of these errors to distinguish clearly between the specified permissible residual unbalance and the reduced residual unbalance values to be achieved during the balancing process.vi ISO 2016 All rights reservedBS I
30、SO 21940-11:2016Mechanical vibration Rotor balancing Part 11: Procedures and tolerances for rotors with rigid behaviour1 ScopeThis document establishes procedures and unbalance tolerances for balancing rotors with rigid behaviour. It specifiesa) the magnitude of the permissible residual unbalance,b)
31、 the necessary number of correction planes,c) the allocation of the permissible residual unbalance to the tolerance planes, andd) how to account for errors in the balancing process.NOTE In ISO 21940-14, the assessment of balancing errors is considered in detail. Fundamentals of rotor balancing are c
32、ontained in ISO 19499 which gives an introduction to balancing.This document does not cover the balancing of rotors with flexible behaviour. Procedures and tolerances for rotors with flexible behaviour are dealt with in ISO 21940-12.2 Normative referencesThere are no normative references in this doc
33、ument.3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 21940-2 apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at http:/www.electropedia.org/ ISO Online browsing pla
34、tform: available at http:/www.iso.org/obp4 Pertinent aspects of balancing4.1 GeneralRotor balancing is a procedure by which the mass distribution of a rotor is examined and, if necessary, adjusted to ensure that the residual unbalance or vibration in service is within specified limits. It should be
35、noted that the vibration in service can originate from sources other than unbalance.Rotor unbalance can be caused by design, material, manufacturing and assembly. Every rotor has an individual unbalance distribution along its length, even in series production.4.2 Representation of the unbalanceFor a
36、 rotor with rigid behaviour, different vectorial quantities can be used to represent the same unbalance as shown in Figure 1.INTERNATIONAL STANDARD ISO 21940-11:2016(E) ISO 2016 All rights reserved 1BS ISO 21940-11:2016ISO 21940-11:2016(E)Figure 1 a) to c) shows different representations in terms of
37、 resultant unbalance and resultant couple unbalance, whereas Figure 1 d) to f) shows different representations in terms of a dynamic unbalance in two planes.NOTE 1 The resultant unbalance vector can be located in any radial plane (without changing magnitude and angle), but the associated resultant c
38、ouple unbalance is dependent on the location of the resultant unbalance vector.NOTE 2 The centre of unbalance is that location on the shaft axis for the resultant unbalance, where the resultant couple unbalance is a minimum.If single-plane balancing is sufficient (see 4.5.2) or when considerations a
39、re made in terms of resultant unbalance and resultant couple unbalance (see 4.5.4), the representation in Figure 1 a) to c) is preferable.In the case of typical two-plane considerations, the representation in Figure 1 d) to f) is advantageous.4.3 Unbalance effectsResultant unbalance and resultant mo
40、ment unbalance (the latter can also be expressed as resultant couple unbalance) have different effects on forces on the bearings and on the vibration of the machine. In practice, therefore, both unbalances are often considered separately. Even if the unbalance is stated as a dynamic unbalance in two
41、 planes, it should be noted that in most cases there is a difference in effects if the unbalances predominantly form either a resultant unbalance or a resultant moment unbalance.4.4 Reference planes for unbalance tolerancesIt is recommended to use reference planes to state the unbalance tolerances.
42、For these planes, only the magnitude of each residual unbalance needs to stay within the respective balance tolerance whatever the angular position may be.The aim of balancing is usually to reduce vibrations and forces transmitted through the bearings to the environment. For the purposes of this doc
43、ument, the reference planes for unbalance tolerances are taken to be the bearing planes. However, this use of bearing planes does not always apply.NOTE For a component without a shaft (e.g. a disc shaped element), but where the final bearing positions are known (or can be estimated), these planes ca
44、n be used.2 ISO 2016 All rights reservedBS ISO 21940-11:2016ISO 21940-11:2016(E)Unbalances in gram millimetresa) Resultant unbalance vector together with an associated couple unbalance in the end planesb) Special case of a), namely resultant unbalance vector located at centre of mass CM (static unba
45、lance), together with an associated couple unbalance in the end planesc) Special case of a), namely resultant unbalance vector located at the centre of unbalance CUd) Unbalance vector in each of the end planese) Two 90 unbalance components in each of the end planesf) Unbalance vector in each of any
46、two other planesKeyCM centre of massCU centre of unbalancel rotor lengthNOTE For Figure 1 c), the associated couple unbalance is a minimum and lays in a plane orthogonal to the resultant unbalance vector.Figure 1 Different representations of the same unbalance of a rotor with rigid behaviour ISO 201
47、6 All rights reserved 3BS ISO 21940-11:2016ISO 21940-11:2016(E)4.5 Correction planes4.5.1 GeneralRotors that are out of unbalance tolerance need correction. These unbalance corrections often cannot be performed in the planes where the unbalance tolerances were set, but need to be performed where mat
48、erial can be added, removed or relocated.The number of necessary correction planes depends on the magnitude and distribution of the initial unbalance, as well as on the design of the rotor, e.g. the shape of the correction planes and their location relative to the tolerance planes.4.5.2 Rotors which
49、 need one correction plane onlyFor some rotors, only the resultant unbalance is out of tolerance but the resultant moment unbalance is in tolerance. This typically happens with rotors having a single disc, provided thata) the bearing distance is sufficiently large,b) the disc rotates with sufficiently small axial runout, andc) the correction plane for the resultant unbalance is properly chosen.After single-plane balancing has been carried out on a sufficient number of rotors, the largest residual moment unbalance is determined and d
