1、BSI Standards PublicationBS ISO 10300-3:2014Calculation of load capacity ofbevel gearsPart 3: Calculation of tooth root strengthBS ISO 10300-3:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 10300-3:2014.It supersedes BS ISO 10300-3:2001 which is withdrawn
2、.The UK participation in its preparation was entrusted to TechnicalCommittee MCE/5/-/13, Bevel gears.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are resp
3、onsible for its correctapplication. The British Standards Institution 2014. Published by BSI StandardsLimited 2014ISBN 978 0 580 71821 2ICS 21.200Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Po
4、licy and Strategy Committee on 31 March 2014.Amendments issued since publicationDate Text affectedBS ISO 10300-3:2014 ISO 2014Calculation of load capacity of bevel gears Part 3: Calculation of tooth root strengthCalcul de la capacit de charge des engrenages coniques Partie 3: Calcul de la rsistance
5、du pied de dentINTERNATIONAL STANDARDISO10300-3Second edition2014-04-01Reference numberISO 10300-3:2014(E)BS ISO 10300-3:2014ISO 10300-3:2014(E)ii ISO 2014 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2014All rights reserved. Unless otherwise specified, no part of this publication may be repr
6、oduced or utilized otherwise in any form or by any means, electronic or mechanical, including 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 requeste
7、r.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 10300-3:2014ISO 10300-3:2014(E) ISO 2014 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope . 12 Normative referenc
8、es 13 Terms and definitions . 14 Symbols, units and abbreviated terms 25 General rating procedure 26 Gear tooth rating formulae Method B1 36.1 Tooth root stress formula 36.2 Permissible tooth root stress 46.3 Calculated safety factor 56.4 Tooth root stress factors . 56.5 Permissible tooth root stres
9、s factors 137 Gear tooth rating formulae Method B2 .177.1 Tooth root stress formula . 177.2 Permissible tooth root stress . 177.3 Calculated safety factor . 187.4 Tooth root stress factors 187.5 Permissible tooth root stress factors 368 Factors for permissible tooth root stress common for method B1
10、and method B2 368.1 Size factor, YX368.2 Life factor, YNT. 38Bibliography .41BS ISO 10300-3:2014ISO 10300-3:2014(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standard
11、s 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 non-governmental, in liaison with ISO, also take
12、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 described in the ISO/IEC Directives, Part 1. In parti
13、cular 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. www.iso.org/directivesAttention is drawn to the possibility that some of the elements of this doc
14、ument 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 ISO list of patent declarations received. www.iso.org/p
15、atentsAny 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 well as information about ISOs adherence to the WTO princip
16、les in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 60, Gears, Subcommittee SC 2, Gear capacity calculation.This second edition cancels and replaces the first edition (ISO 10300-3:2001), which h
17、as been technically revised.ISO 10300 consists of the following parts, under the general title Calculation of load capacity of bevel gears: Part 1: Introduction and general influence factors Part 2: Calculation of surface durability (pitting) Part 3: Calculation of tooth root strengthiv ISO 2014 All
18、 rights reservedBS ISO 10300-3:2014ISO 10300-3:2014(E)IntroductionWhen ISO 10300:2001 (all parts, withdrawn) became due for (its first) revision, the opportunity was taken to include hypoid gears, since previously the series only allowed for calculating the load capacity of bevel gears without offse
19、t axes. The former structure is retained, i.e. three parts of the ISO 10300 series, together with ISO 6336-5, and it is intended to establish general principles and procedures for rating of bevel gears. Moreover, ISO 10300 (all parts) is designed to facilitate the application of future knowledge and
20、 developments, as well as the exchange of information gained from experience.In view of the decision for ISO 10300 (all parts) to cover hypoid gears also, it was agreed to include a separate clause: “Gear tooth rating formulae Method B2” in this part of ISO 10300, while the former methods B and B1 w
21、ere combined into one method, i.e. method B1. So, it became necessary to present a new, clearer structure of the three parts, which is illustrated in ISO 10300-1:2014, Figure 1. Note, ISO 10300 (all parts) gives no preferences in terms of when to use method B1 and when method B2.Failure of gear teet
22、h by breakage can be brought about in many ways; severe instantaneous overloads, excessive pitting, case crushing and bending fatigue are a few. The strength ratings determined by the formulae in this part of ISO 10300 are based on cantilever projection theory modified to consider the following: com
23、pressive stress at the tooth roots caused by the radial component of the tooth load; non-uniform moment distribution of the load, resulting from the inclined contact lines on the teeth of spiral bevel gears; stress concentration at the tooth root fillet; load sharing between adjacent contacting teet
24、h; lack of smoothness due to a low contact ratio.The formulae are used to determine a load rating, which prevents tooth root fracture during the design life of the bevel gear. Nevertheless, if there is insufficient material under the teeth (in the rim), a fracture can occur from the root through the
25、 rim of the gear blank or to the bore (a type of failure not covered by this part of ISO 10300). Moreover, it is possible that special applications require additional blank material to support the load.Surface distress (pitting or wear) can limit the strength rating, either due to stress concentrati
26、on around large sharp cornered pits, or due to wear steps on the tooth surface. Neither of these effects is considered in this part of ISO 10300.In most cases, the maximum tensile stress at the tooth root (arising from bending at the root when the load is applied to the tooth flank) can be used as a
27、 determinant criterion for the assessment of the tooth root strength. If the permissible stress number is exceeded, the teeth can break.When calculating the tooth root stresses of straight bevel gears, this part of ISO 10300 starts from the assumption that the load is applied at the tooth tip of the
28、 virtual cylindrical gear. The load is subsequently converted to the outer point of single tooth contact. The procedure thus corresponds to method C for the tooth root stress of cylindrical gears (see ISO 6336-31).For spiral bevel and hypoid gears with a high face contact ratio of v 1 (method B1) or
29、 with a modified contact ratio of v 2 (method B2), the midpoint in the zone of action is regarded as the critical point of load application.The breakage of a tooth generally means the end of a gears life. It is often the case that all gear teeth are destroyed as a consequence of the breakage of a si
30、ngle tooth. A safety factor, SF, against tooth breakage higher than the safety factor against damage due to pitting is, therefore, generally to be preferred (see ISO 10300-1). ISO 2014 All rights reserved vBS ISO 10300-3:2014BS ISO 10300-3:2014Calculation of load capacity of bevel gears Part 3: Calc
31、ulation of tooth root strength1 ScopeThis part of ISO 10300 specifies the fundamental formulae for use in the tooth root stress calculation of straight and helical (skew), Zerol and spiral bevel gears including hypoid gears, with a minimum rim thickness under the root of 3,5 mmn. All load influences
32、 on tooth root stress are included, insofar as they are the result of load transmitted by the gearing and able to be evaluated quantitatively. Stresses, such as those caused by the shrink fitting of gear rims, which are superposed on stresses due to tooth loading, are intended to be considered in th
33、e calculation of the tooth root stress, F, or the permissible tooth root stress FP. This part of ISO 10300 is not applicable in the assessment of the so-called flank breakage, a tooth internal fatigue fracture (TIFF).The formulae in this part of ISO 10300 are based on virtual cylindrical gears and r
34、estricted to bevel gears whose virtual cylindrical gears have transverse contact ratios of v45, for effective pressure angles e 30 and/or for large face widths b 13 mmn, the calculated results of ISO 10300 (all parts) should be confirmed by experience.2 Normative referencesThe following documents, i
35、n whole or in part, are normatively referenced in this document and are indispensable to its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 1122-1, Vocabulary of gear term
36、s Part 1: Definitions related to geometryISO 6336-5, Calculation of load capacity of spur and helical gears Part 5: Strength and quality of materialsISO 10300-1:2014, Calculation of load capacity of bevel gears Part 1: Introduction and general influence factorsISO 10300-2:2014, Calculation of load c
37、apacity of bevel gears Part 2: Calculation of surface durability (pitting)ISO 23509:2006, Bevel and hypoid gear geometry3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 1122-1 and ISO 23509 (geometrical gear terms) and the following apply.INTERNATIONAL
38、 STANDARD ISO 10300-3:2014(E) ISO 2014 All rights reserved 1BS ISO 10300-3:2014ISO 10300-3:2014(E)3.1tooth root breakagefailure of gear teeth at the tooth root by static or dynamic overload3.2nominal tooth root stressF0bending stress in the critical section of the tooth root calculated for the criti
39、cal point of load application for error-free gears loaded by a constant nominal torque3.3tooth root stressFdeterminant bending stress in the critical section of the tooth root calculated for the critical point of load application including the load factors which consider static and dynamic loads and
40、 load distribution3.4nominal stress numberF,limmaximum tooth root stress of standardized test gears and determined at standardized operating conditions as specified in ISO 6336-53.5allowable stress numberFEmaximum bending stress of the un-notched test piece under the assumption that the material is
41、fully elastic3.6permissible tooth root stressFPmaximum tooth root stress of the evaluated gear set including all influence factors4 Symbols, units and abbreviated termsFor the purposes of this document, the symbols and units given in Table 1 and Table 2 of ISO 10300-1:2014, as well as the abbreviate
42、d terms given in Table 1 of ISO 10300-2:2014, apply (see ISO 6336-5).5 General rating procedureThere are two main methods for determining tooth bending strength of bevel and hypoid gears: method B1 and method B2. They are provided in Clauses 6 and 7, while Clause 8 contains those influence factors w
43、hich are equal for both methods. With method B1, the same set of formulae may be used for bevel and hypoid gears; method B2 partly has different sets of formulae for bevel gears and for hypoid gears (see 7.4.3 for general aspects).With both methods, the capability of a gear tooth to resist tooth roo
44、t stresses shall be determined by the comparison of the following stress values: tooth root stress F, based on the geometry of the tooth, the accuracy of its manufacture, the rigidity of the gear blanks, bearings and housing, and the operating torque, expressed by the tooth root stress formula (see
45、6.1 and 7.1); permissible tooth root stress FP, based on the bending stress number, F,lim, of a standard test gear and the effect of the operating conditions under which the gears operate, expressed by the permissible tooth root stress formula (see 6.2 and 7.2).2 ISO 2014 All rights reservedBS ISO 1
46、0300-3:2014ISO 10300-3:2014(E)NOTE In respect of the permissible tooth root stress, reference is made to a stress “number”, a designation adopted because pure stress, as determined by laboratory testing, is not calculated by the formulae in this part of ISO 10300. Instead, an arbitrary value is calc
47、ulated and used in this part of ISO 10300, with accompanying changes to the allowable stress number in order to maintain consistency for design comparison.The ratio of the permissible root stress and the calculated root stress is the safety factor SF. The value of the minimum safety factor for tooth
48、 root stress, SF,min, should be 1,3 for spiral bevel gears. For straight bevel gears, or where m 5, SF,minshould be 1,5.It is recommended that the gear designer and customer agree on the value of the minimum safety factor.Tooth breakage usually ends transmission service life. The destruction of all
49、gears in a transmission can be a consequence of the breakage of one tooth, then, the drive train between input and output shafts is interrupted. Therefore, the chosen value of the safety factor, SF, against tooth breakage should be carefully chosen to fulfil the application requirements (see ISO 10300-1 for general comments on the choice of safety factor).6 Gear tooth rating formulae Method B16.1 Tooth root stress formulaThe calculation of the tooth root stress is based on the maximum bending stress at the
