1、BRITISH STANDARDBS ISO 281:2007Incorporating corrigendum May 2008Rolling bearings Dynamic load ratings and rating life ICS 21.100.20g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50
2、g51g60g53g44g42g43g55g3g47g36g58BS ISO 281:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 March 2007 BSI 2008ISBN 978 0 580 63046 0National forewordThis British Standard is the UK implementation of ISO 281:2007. It supersedes BS 5512:
3、1991 and BS ISO/TS 16799:1999, which are withdrawn.The UK participation in its preparation was entrusted to Technical Committee MCE/7, Rolling bearings.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all t
4、he necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments/corrigenda issued since publicationDate Comments30 May 2008 Correcting BibliographyReference numberISO 281:2007(E)INTER
5、NATIONAL STANDARDISO281Second edition2007-02-15Rolling bearings Dynamic load ratings and rating life Roulements Charges dynamiques de base et dure nominale BS ISO 281:2007ii iiiContents PageForewordivIntroductionv1Scope.12Normative references.13Terms and definitions.24Symbols.45Radial ball bearings6
6、5.1 Basic dynamic radial load rating.65.2 Dynamic equivalent radial load.95.3 Basic rating life.106Thrust ball bearings106.1Basic dynamic axial load rating106.2Dynamic equivalent axial load.126.3Basic rating life.137Radial roller bearings.137.1Basic dynamic radial load rating.137.2Dynamic equivalent
7、 radial load.157.3Basic rating life.168Thrust roller bearings.168.1Basic dynamic axial load rating168.2Dynamic equivalent axial load.198.3Basic rating life.199Modified rating life209.1General.209.2Life modification factor for reliability.209.3Life modification factorfor systems approach.21Annex A (i
8、nformative) Detailed method for estimating the contamination factor.32Annex B (informative) Calculation of the fatigue load limit.42Annex C (informative) Discontinuities in the calculation of basic dynamic load ratings.47Bibliography.51BS ISO 281:2007iv Foreword ISO (the International Organization f
9、or Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member bodyinterested in a subject for which a technical committee has beenestablished has the
10、right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closelywith the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Internation
11、al Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.The main task of technical committees is to prepare International Standards. Draft International Standardsadopted by the technical committees are circulated to the member bodies for voting. Publication as a
12、n International Standard requires approval byat least 75 % of the member bodies casting a vote. Attention is drawn to 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. ISO28
13、1 was prepared by Technical Committee ISO/TC4, Rolling bearings, Subcommittee SC 8, Load ratings and life. This second edition cancels and replaces the first edition (ISO281:1990),ISO281:1990/Amd. 1:2000,ISO 281:1990/Amd. 2:2000 and ISO/TS 16799:1999, which have been technicallyrevised.BS ISO 281:20
14、07vIntroduction It is often impractical to establish the suitabilityof a bearing selected for a specific application by testing a sufficient number of bearings in that application. However, life, as defined in 3.1, is a primary representation ofthe suitability. A reliable life calculation is therefo
15、re considered to be an appropriate and convenient substitutefor testing. The purpose of this International Standard is to provide the required basis for life calculation. Since ISO281 was published in 1990, additional knowledge has been gained regarding the influence on bearing life of contamination
16、, lubrication, internal stresses from mounting, stresses from hardening, fatigue load limit of the material, etc. In ISO281:1990/Amd. 2:2000, a general method was presented to considersuch influences in the calculation of a modified rating life of a bearing. This amendment is incorporated in thisInt
17、ernational Standard, which also provides a practical method to consider the influence on bearing life of lubrication condition, contaminated lubricant and fatigue load of bearing material.ISO/TS 16281 1 introduced advanced calculation methods which enable the user to take into account theinfluence o
18、n bearing life of bearing-operating clearance and misalignment under general loading conditions.The user can also consult the bearing manufacturer for recommendations and evaluation of equivalent load and life for these operation conditions and other influences as, forexam ple, rolling element centr
19、ifugal forces or other high-speed effects.Calculations according to this International Standard do not yield satisfactory results for bearings subjected tosuch application conditions and/or of such internal design which result in considerable truncation of the area of contact between the rolling ele
20、ments and the ring raceways. Unmodified calculation results are thus not applicable, for example, to ball bearings with filling slots that project substantially into the ball/raceway contact area when the bearing is subjected to axial loading in the application. Bearing manufacturers should beconsul
21、ted in such cases.The life modification factors for reliability, a 1 , have been slightly changed and extended to 99,95 % reliability.Revisions of thisdocument will be required from time to time, as the result of new developments or in the light of new information concerning specific bearing types a
22、nd materials.Background information regarding the derivation of equations and factors in this document is given inISO/TR 86461) and ISO/TR 1281-2 2. 1) Under revision. Willbe published under the reference ISO/TR 1281-1. BS ISO 281:2007blank1Rolling bearings Dynamic load ratings and rating life 1 Sco
23、pe This International Standard specifies methods of calculating the basic dynamic load rating of rolling bearingswithin the size ranges shown in the relevant ISO publications, manufactured from contemporary, commonlyused, high quality hardened bearing steel, in accordance with good manufacturing pra
24、ctice and basicallyof conventional design as regards the shape of rolling contact surfaces. This document also specifies methods of calculating the basic rating life, which is the life associated with 90 % reliability, with commonlyused high quality material, good manufacturing qualityand with conve
25、ntional operating conditions. In addition, it specifies methods of calculating the modified ratinglife, in which various reliabilities,lubrication condition, contaminated lubricant and fatigue load of the bearing are taken into account.This International Standard does not cover the influence of wear
26、, corrosionand electrical erosionon bearinglife. This document is not applicable to designs where the rolling elements operate dir ectly on a shaft or housing surface, unless that surface is equivalent in all respects to the bearing ring (orwasher) raceway it replaces. Double-row radial bearings and
27、 double-direction thrust bearings are, when referred to in this document,presumed to be symmetrical. Further limitations concerning particular types of bearings are included in the relevant clauses.2 NormativereferencesThe following referenced documents are indispensable for the application of this
28、document. For datedreferences, only the edition cited applies. For undated references, the latest edition of the r eferenceddocument (including anyamendments) applies.ISO 76, Rolling bearings Static load ratingsISO 5593, Rolling bearings Vocabulary ISO/TR 8646:1985, Explanatory notes on ISO 281/1-19
29、772)ISO 15241, Rolling bearings Symbols for quantities2) Under revision. Willbe published under the reference ISO/TR 1281-1. BS ISO 281:20072 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 5593 and the following apply.3.1 life of an individual rolli
30、ng bearing number of revolutions which one of the bearing rings or washers makes in relation to the other ring or washer before the first evidence of fatigue dev elops in the material of one of therings orwashers or one of the rolling elementsNOTE Life may also be expressed in number of hours of ope
31、ration at a given constant speed of rotation. 3.2 reliability in the context of bearing life for a group of apparently identical rolling bearings, operating under the sameconditions, the percentage of the group that is expected to attain or exceed a specified life NOTE The reliability of an individu
32、al rolling bearing is the probability that the bearing will attain orexceed a specifiedlife. 3.3 rating lifepredictedvalue of life based on a basic dynamic radial load rating or a basic dynamic axial load rating 3.4 basic ratinglife rating life associated with 90 % reliability for bearings manufactu
33、red with commonlyused high quality material, of good manufacturing quality, and operating under conventional operating conditions3.5 modified rating liferating life modified for 90 % or other reliability,bearing fatigue load, and/or special bearing properties, and/orcontaminated lubricant, and/or ot
34、her non-conventional operating conditionsNOTE The term “modified rating life” is new in this document and replaces “adjusted rating life”. 3.6 basic dynamic radial load ratingconstant stationary radial load which a rolling bearing can theoretically endure for a basic rating life of onemillion revolu
35、tionsNOTE In the case of a single-row angular contact bearing, the radial load rating refers to the radial component of thatload which causes a purely radial displacement of the bearing rings in relation to each other. 3.7 basic dynamic axial loadratingconstant centric axial loadwhich a rolling bear
36、ing can theoretically endure for abasic ratinglife of one million revolutions3.8 dynamicequivalent radial loadconstant stationary radial load under the influence of which a rolling bearing would have the same life as it would attain under the actual load conditions3.9 dynamic equivalentaxial loadcon
37、stant centric axial load under the influence of which a rolling bearing would have the same life as it would attain under the actual load conditionsBS ISO 281:200733.10 fatigue load limit bearing load under which the fatigue stress limit, u , is just reached in the most heavily loaded raceway contac
38、t 3.11 roller diameter applicable in the calculation of load ratings theoretical diameter in a radial plane through the middle of the roller length for a symmetrical rollerNOTE1 For a tapered roller, the applicable diameter is equal to the mean value of the diameters at the imaginarysharp corners at
39、 the large endand at the small end of the roller. NOTE2For an asymmetrical convex roller, the applicable diameter is an approximation of the diameter at the point ofcontact between the roller and the ribless raceway at zero load. 3.12 effective roller length applicable in the calculation of load rat
40、ings theoretical maximum length of contact between a roller and that racewaywhere the contact is shortestNOTE This is normally taken to be either the distance between thetheoretically sharp corners of the roller minus theroller chamfers or the raceway width, excluding the grinding undercuts, whichev
41、er is the smaller. 3.13 nominal contactangleangle between a plane perpendicular to a bearing axis (a radial plane) and the nominal line of action of theresultant of the forces transmitted bya bearing ring or washer to a rolling element NOTE For bearings with asymmetrical rollers, the nominal contact
42、 angle is determined by the contact with thenon-ribbed raceway. 3.14 pitch diameter of ball setdiameter of the circle containing the centres of the balls in one row in a bearing 3.15 pitch diameter of rollerset diameter of the circle intersecting the roller axes at the middle of the rollers in one r
43、ow in a bearing 3.16 conventional operating conditionsconditions which may be assumed to prevail fora bearing whichis properly mounted and protected fromforeign matter, adequately lubricated, conventionallyloaded, not exposed to extreme temperature and not runat exceptionallylow or high speed 3.17 v
44、iscosity ratioactual kinematic oil viscosity at operating temperature divided by the reference kinematic viscosity foradequate lubrication 3.18 film parameterratio of lubricant film thickness to composite r.m.s. surface roughness, used to estimate the influence oflubrication on bearing life3.19 pres
45、sure-viscosity coefficientparameter characterizing the influence of oil pressure on the oil viscosityin the rolling element contact BS ISO 281:20074 3.20 viscosity index index characterizing the degree of influence of temperature on the viscosity of lub ricating oils4 Symbols For the purposes of thi
46、s document, the symbols given in ISO 15241 and the following apply.a ISO life modification factor, based on a systems approach of life calculation a 1 life modification factor for reliabilityb m rating factor for contemporary, commonlyused, high quality hardened bearing steel in accordance with good
47、 manufacturing practices, the value of which varieswith bearing type and design C a basic dynamic axial load rating, in newtonsC r basic dynamic radialload rating, in newtonsC u fatigue load limit, in newtonsC 0a basic static axial load rating3), in newtonsC 0r basic static radial load rating3), in
48、newtonsD bearing outside diameter, in millimetresD pw pitch diameter of ball or roller set, in millimetresD w nominal ball diameter, in millimetresD we roller diameter applicable in the calculation of load ratings, in millimetresd bearing bore diameter, in millimetrese limiting value of F a / F r fo
49、r the applicabilityof different values of factors X and Ye C contamination factorF a bearing axial load (axial component of actual bearing load), in newtonsF r bearing radialload (radial component of actual bearing load), in newtonsf c factor which depends on the geometry of the bearing components, the accuracy to which the variouscomponents are made, and the materialf 0 factor for calculation of basic static load rating3)i number of rows of rolling elements3) For definitions, calculation methods and values of C 0a, C 0r and f 0 , see ISO76. BS ISO 281:20075
