BS-1726-3-1988.pdf
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1、BRITISH STANDARD BS 1726-3: 1988 Incorporating Amendment No. 1 Coil springs Part 3: Guide for the design of helical torsion springs UDC 62 272.2:62 567.143:62 11:655.246.1:51:620.1:(083.71) Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:08:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS
2、1726-3:1988 This British Standard, having been prepared under the direction of the General Mechanical Engineering Standards Committee, was published under the authority of the Board of BSI and comes into effect on 31 January 1989 BSI 03-1999 The following BSI references relate to the work on this st
3、andard: Committee reference GME/15 Draft for comment 86/72812 DC ISBN 0 580 16738 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the General Mechanical Engineering Standards Committee (GME/-) to Technical Committee GME/15, upon which the
4、following bodies were represented: British Railways Board London Regional Transport National Federation of Scale and Weighing Machine Manufacturers Railway Industry Association of Great Britain Royal Ordnance Spring Research and Manufacturers Association Amendments issued since publication Amd. No.D
5、ate of issueComments 6668February 1991Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:08:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1726-3:1988 BSI 03-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Definitions1 3
6、Symbols1 4General2 5Methods of calculation2 6Tolerances5 Appendix A Methods of specifying springs for general purposes7 Appendix B Methods of testing12 Appendix C Modulus of elasticity of some materials13 Appendix D Typical tolerances on rectangular section material13 Figure 1 Forms of legs3 Figure
7、2 Conventions for describing relative leg orientation4 Figure 3 Direction of coiling7 Figure 4 Data sheet 19 Figure 5 Example torque testing layout10 Figure 6 Data sheet 211 Table 1 Calculated free relative leg orientation tolerance5 Table 2 Typical tolerances on rectangular section material13 Publi
8、cations referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:08:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1726-3:1988 ii BSI 03-1999 Foreword This Part of BS 1726 has been prepared under the direction of the General Mechanical Engineering Standards Committee.
9、 It is one of a series of three guides relating to the design of helical springs: Part 1 deals with helical compression springs and Part 2 with helical extension springs. NOTEThere are numerous methods of calculating the parameters necessary for the design of springs and initially the designer is fr
10、ee to use any one of these. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pa
11、ges This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 14, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cove
12、r. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:08:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1726-3:1988 BSI 03-19991 1 Scope This Part of BS 1726 provides guidance on the design of parallel-sided helical torsion springs manufactured from either: a) circular section material, or
13、b) rectangular and square section material. It applies to springs which may or may not be stress relieved after forming (hereinafter referred to as group A springs) and to springs the material of which has undergone a structural change by heat treatment after forming (hereinafter referred to as grou
14、p B springs). In the case of torsion springs manufactured from square or rectangular material the ratio of the radial to axial dimensions of the section is important. This ratio (known as the shape factor, m) becomes significant at values greater than 2.5 or less than 0.4 because of the extreme diff
15、iculty in coiling springs accurately and repeatedly. For this reason this specification is only valid for shape factors in the range 2.5 to 0.4. Appendix A gives two methods of specifying springs. Methods of testing springs are described in Appendix B. Values of the modulus of elasticity of some mat
16、erials are given in Appendix C. Typical tolerances on rectangular section material are given in Appendix D. NOTE 1It is not recommended that torsion springs be loaded in the opposite direction to that of coiling. If this is necessary then discussions should take place between purchaser and supplier.
17、 NOTE 2The titles of the publications referred to in this Part of this standard are given on the inside back cover. 2 Definitions For the purposes of this Part of BS 1726 the definitions given in BS 1726-1 apply. 3 Symbols SymbolTermUnit bradial dimension of rectangular section material mm cspring i
18、ndexmm Dmean coil diametermm Dchange in mean coil diameter mm Dooutside diametermm Dtolmean coil diameter tolerance mm dmaterial diametermm SymbolTermUnit dmaxmaximum diameter of circular section material allowing for material size tolerance mm etolerance on size of material cross section mm Emodulu
19、s of elasticity (see Appendix C) N/mm2 FTtolerance factor for torque haxial dimension of rectangular section material mm h9maximum axial dimension of rectangular section material after coiling mm hmaxmaximum axial dimension of rectangular section material allowing for material size tolerance mm kmat
20、erial constant for calculation of distortion and axial dimension of rectangular section material after coiling Kostress correction factor for circular section wire Krstress correction factor for rectangular section wire lcombined effective length of legs mm Lofree body length of springmm Lo(tol)tole
21、rance on free body length mm Ltloaded body length of spring mm mshape factormm nnumber of active coils in spring nchange in number of active coils during loading Ntotal number of coils in spring ppitchmm Rminminimum allowable inside radius of any bend mm Snominal torsional rateNmm/degree Licensed Co
22、py: sheffieldun sheffieldun, na, Fri Nov 24 06:08:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1726-3:1988 2 BSI 03-1999 4 General 4.1 When designing a spring certain characteristics have to be determined, for example, stress, rate, number of coils and the tolerances which can be permitted to en
23、sure that it functions as required but which will allow it to be produced economically. 4.2 Two methods of specifying springs for general purposes are given in Appendix A. The first of these methods deals with the complete specification of a spring when all the relevant information is available for
24、the spring manufacturer to produce the spring required. The information can be provided to the manufacturer by the customer completing data sheet 1. Advice on the completion of data sheet 1 is given in A.2. When the customer does not have the information to complete data sheet 1, he may use the seco
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