1、BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06Plain bearings Quality assurance of thin-walled half bearings Selective assembly of bearings to achieve a narrow clearance rangeBS ISO 13778:2017National forewordThis British Standard is the UK implementation of ISO 137
2、78:2017. It supersedes BS ISO 13778:1999, which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee MCE/12, Plain bearings.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to incl
3、ude all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017 Published by BSI Standards Limited 2017ISBN 978 0 580 92912 0ICS 21.100.10Compliance with a British Standard cannot confer immunity from legal obligations. This B
4、ritish Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2017.Amendments/corrigenda issued since publicationDate Text affected BRITISH STANDARDBS ISO 13778:2017 ISO 2017Plain bearings Quality assurance of thin-walled half bearings Selective assembl
5、y of bearings to achieve a narrow clearance rangePaliers lisses Assurances qualit des demi-coussinets minces Assemblage slectif des paliers pour obtenir un jeu faibleINTERNATIONAL STANDARDISO13778Second edition2017-03-15Reference numberISO 13778:2017(E)BS ISO 13778:2017ISO 13778:2017(E)ii ISO 2017 A
6、ll rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2017, 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, including photocopying, or posting on the inter
7、net 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. +41 22 749 01 11Fax +41 22 749 09 47copyri
8、ghtiso.orgwww.iso.orgBS ISO 13778:2017ISO 13778:2017(E)Foreword iv1 Scope . 12 Normative references 13 Terms and definitions . 14 Housing swell and thermal expansion . 25 Measurement and identification . 25.1 Housings and journals 25.2 Bearings 26 Suggested schemes for fitting . 36.1 General . 36.2
9、Scheme 1: Standard application, without grading . 36.3 Scheme 2: Grading of bearings 46.4 Scheme 3: Grading of bearings and journals or housings 46.5 Scheme 4: Unmixed bearings (Matrix scheme) 56.6 Scheme 5: Mixed bearings (Matrix scheme) 66.7 Scheme 6: Mixed bearings (fine matrix) . 6 ISO 2017 All
10、rights reserved iiiContents PageBS ISO 13778:2017ISO 13778:2017(E)ForewordISO (the International Organization for 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 c
11、ommittees. 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 non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with t
12、he 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 described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for
13、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 the possibility that some of the elements of this document may be the subject of patent rights.
14、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 ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this doc
15、ument is information given for the convenience of users and does not constitute an endorsement.For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade O
16、rganization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.This document was prepared by Technical Committee ISO/TC 123, Plain bearings, Subcommittee SC 5, Quality analysis and assurance.This second edition cancels and replaces the firs
17、t edition (ISO 13778:1999), which has been technically revised.iv ISO 2017 All rights reservedBS ISO 13778:2017Plain bearings Quality assurance of thin-walled half bearings Selective assembly of bearings to achieve a narrow clearance range1 ScopeThis document specifies the selective assembly of bear
18、ings (in accordance with ISO 35481).The bearing diametral clearance is determined by the housing diameter, journal diameter and the wall thickness of the two half bearings. Typically, these components will have a total tolerance “stack up” of 50 m to 60 m. Current engine development and in particula
19、r, the desire for improved engine refinement, has provided a need to decrease the clearance range due to the tolerance “stack up”. This document suggests various schemes of selective assembly to achieve such ranges.2 Normative referencesThe following documents are referred to in the text in such a w
20、ay that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 3548-1, Plain bearings Thin-walled half bearings with or
21、without flange Part 1: Tolerances, design features and methods of testISO 4378-1, Plain bearings Terms, definitions, classification and symbols Part 1: Design, bearing materials and their properties3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 43781
22、 and the following 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 platform: available at http:/www.iso.org/obp3.1theoretical bearing diametral clearanceC differe
23、nce between the housing diameter, DH, less twice the half bearing wall thickness (3.3), s3, and the journal diameter (3.4), DJC = DH (2s3+ DJ)3.2housing diameterD Hdiameter of the housing with no bearing fitted measured perpendicular to the split lineINTERNATIONAL STANDARD ISO 13778:2017(E) ISO 2017
24、 All rights reserved 1BS ISO 13778:2017ISO 13778:2017(E)3.3bearing wall thicknesss 3wall thickness measured at 90 from the split line (at the “crown”)Note 1 to entry: If two measurements are made, the larger of the two is used.3.4journal diameterD Jdiameter of the finished shaft measured at a positi
25、on to give maximum diameter3.5tolerancerange between the upper and lower limits specified on the drawing3.6housing swellexpansion of a housing bore caused by the interference fit of the bearings4 Housing swell and thermal expansionHousing swell is defined as the “expansion of a housing bore, caused
26、by the interference fit of the bearings”. When two half bearings are assembled into a housing and the housing is bolted up, the assembled bore will be slightly greater than the arithmetical subtraction of the two bearing wall thicknesses from the housing diameter as measured before the bearing is fi
27、tted. Housing swell is generally of the order of a few micrometres. Maximum housing swell will occur with a combination of maximum bearing overstand (nip) and minimum housing diameter. It is prudent to measure actual housing swell by carrying out fitting tests. Actual housing deformation may also be
28、 affected by the degree of control of bolt tension.With light alloy housings, the housing swell may be larger, due not only to the lower modulus of elasticity but also to thermal expansion.Allowance for housing swell and thermal expansion has to be made when setting the bearing diametral clearance.5
29、 Measurement and identification5.1 Housings and journalsSpecific measurement of each housing and journal may be necessary in more complex grading schemes. While bearings will be graded according to only the crown wall thickness, journals in particular may have to be measured in several places, both
30、axially and circumferentially, to ascertain the mean journal diameter. The crown housing diameter may be the only housing measurement necessary. With grade tolerances of a few micrometres, accurate measurement with minimal dirt and constant temperature is necessary.Traditionally, crankshaft journals
31、 of different grades have been identified with a dab of paint or ink adjacent to the journal. Housings have been similarly identified. Such a method relies upon the visual discrimination of the operator and this may on occasions be unreliable. One alternative is to bar or dot code the housing and/or
32、 journal with either adhesive labels or by etching. Another is to store the data on computer for retrieval at assembly stage.5.2 BearingsIf bearing grades with wall thickness tolerances of less than the normal process capability are required, then consideration shall be given as to how the bearings
33、are graded and identified. The part number is 2 ISO 2017 All rights reservedBS ISO 13778:2017ISO 13778:2017(E)stamped upon the bearing prior to final wall thickness machining. Additional stamping after bearing grading is not feasible as this will create high spots of wall thickness. The usual practi
34、ce is to mark the bearing side face after grading with a permanent colour code or with other suitable methods.6 Suggested schemes for fitting6.1 GeneralThe selective assembly of bearings shall be in accordance with ISO 3548-1.Before choosing the scheme for selectively fitting bearings, it is first n
35、ecessary to set the desired clearance range. As a general rule, the narrower the clearance range, the more complex the grading scheme will be and the tighter the tolerance on each component. As an example, if a clearance range of 24 m is required, this could entail grade tolerances of 6 m, while wit
36、h a clearance range of 32 m, grade tolerances of 8 m would be acceptable.While it may be desirable from the design viewpoint to achieve a very narrow clearance range, there may come a point at which perceived performance gains from working very close to the desired mean clearance become offset by th
37、e cost and complexity of the selective fitting scheme.While such schemes are feasible for OE engine assembly, they are not practical for replacement bearings where the bearings are packed in sets of similar sizes.Other points to consider are as follows.a) Due to the normal distribution of journal an
38、d housing sizes, the required quantity of each bearing grade will not necessarily be equal. Carefully controlled scheduling will be necessary in order to minimize bearing stocks and prevent shortages of particular bearing grades.b) Intermediate grades can be formed by fitting together half bearings
39、from adjacent grades. This can significantly increase the flexibility of the system.c) If it is necessary to grade bearings by measurement after final wall thickness machining, then overlapping bearing grades are permissible and in fact allow the bearing supplier flexibility in achieving correct qua
40、ntities of each bearing grade.d) When choosing a grading scheme, the difference in process capability for wall thickness between bimetallic and multi-layer should be taken into account.The schemes described in 6.2 to 6.7 are examples only.6.2 Scheme 1: Standard application, without gradingThe cleara
41、nce shall be determined by the limitations of normal process capability (see Table 1).Housing diameter, DH: not gradedJournal diameter, DJ: not gradedBearing wall thickness, s3: not gradedTable 1 Standard application; without gradingDimensions in millimetresGrade Without gradingDH50,000 to 50,018DJ4
42、6,000 to 46,018 ISO 2017 All rights reserved 3BS ISO 13778:2017ISO 13778:2017(E)Grade Without gradings31,972 to 1,978C 0,026 to 0,0746.3 Scheme 2: Grading of bearingsScheme 2 is applicable where a slight reduction in the clearance tolerance is required. The bearings are graded to effectively reduce
43、the tolerance of the grade (see Table 2).Housing diameter, DH: not gradedJournal diameter, DJ: not gradedBearing wall thickness, s3: three grades of 4 mTable 2 Grading of bearingsDimensions in millimetresGrade A B CDHa50,000 to 50,018DJa46,000 to 46,018s31,970 to 1,974 1,974 to 1,978 1,978 to 1,982C
44、b0,026 to 0,070aWithout grading.bAccording to the selection procedure.Depending on the selection procedure, fit as a bearing pair, either two of grade B or one of grade A and one of grade C.NOTE 1 The scheme is simple to administer.NOTE 2 Compared to scheme 1, the clearance range of 0,026 mm to 0,07
45、4 mm is reduced to 0,026 mm to 0,070 mm.6.4 Scheme 3: Grading of bearings and journals or housingsThe housing or the journal is graded, usually into two or three grades and the bearings are graded into a similar number of grades (see Table 3).Housing diameter, DH: not gradedJournal diameter, DJ: thr
46、ee grades of 6 m grade toleranceBearing wall thickness, s3: three grades of 4 m grade toleranceTable 3 Grading of bearings and journals or housingsDimensions in millimetresGrade A B CDHa50,000 to 50,018DJ46,000 to 46,006 46,006 to 46,012 46,012 to 46,018aWithout grading.4 ISO 2017 All rights reserve
47、dBS ISO 13778:2017ISO 13778:2017(E)Grade A B Cs31,984 to 1,980 1,981 to 1,977 1,978 to 1,974C 0,026 to 0,058aWithout grading.NOTE 1 The spacing of each bearing grade is determined by the spacing of each journal grade in order to achieve an identical clearance range for each combination.NOTE 2 Compar
48、ed to scheme 2, the clearance range of 0,026 mm to 0,070 mm is reduced to 0,026 mm to 0,058 mm.NOTE 3 Overlapping grades are used effectively.NOTE 4 The scheme is simple to administer.6.5 Scheme 4: Unmixed bearings (Matrix scheme)Housing and journal diameter both graded with equal grade tolerances.
49、With an equal number of housing and journal grades, the matrix is symmetrical and the distribution of bearings will be even. The bearing wall thickness grade tolerance is half that of the housing to journal diameter grade tolerance (see Table 4 and Table 5).Housing diameter, DH: three grades of 6 m grade toleranceJournal diameter, DJ: three grades of 6 m grade toleranceBearing wall thickness, s3: five grades of 3 m grade toleranceTable 4 Unmixed bearingsDimensions in millimetresGrade A B C D EDH50,000 to 5
