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1、BRITISH STANDARD BS EN 13906-2:2001 Cylindrical helical springs made from round wire and bar Calculation and design Part 2: Extension springs The European Standard EN 13906-2:2001 has the status of a British Standard ICS 21.160 BS EN 13906-2:2001 This British Standard, having been prepared under the
2、 direction of the Engineering Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 16 May 2002 BSI 16 May 2002 ISBN 0 580 37416 5 National foreword This British Standard is the official English language version of EN 13906-2:2001.
3、It partially supersedes BS 1726-2:1988 which is being revised. The UK participation in its preparation was entrusted to Technical Committee GME/15, Mechanical springs, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary.
4、Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Elect
5、ronic Catalogue. 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. aid enquirers to underst
6、and the text; present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover,
7、 an inside front cover, the EN title page, pages 2 to 16, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM
8、EN 13906-2 December 2001 ICS 21.160 English version Cylindrical helical springs made from round wire and bar - Calculation and design - Part 2: Extension springs Ressorts hlicodaux cylindriques fabriqus partir de fils ronds et de barres - Calcul et conception - Partie 2: Ressorts de traction Zylindr
9、ische Schraubenfedern aus runden Drhten und Stben - Berechnung und Konstruktion - Teil 2: Zugfedern This European Standard was approved by CEN on 5 January 2001. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
10、 the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, Germa
11、n). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finla
12、nd, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels
13、2001 CENAll rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 13906-2:2001 E Contents Foreword3 1Scope 4 2Normative references4 3Terms and definitions, symbols, units and abbreviated terms 4 3.1Terms and definitions4 3.2Symbols, units and ab
14、breviated terms5 4Theoretical extension spring diagram.7 5Types of loading 7 5.1Static and/or quasi-static loading7 5.2Dynamic loading7 6Stress correction factor k.8 7Initial tension force F0.9 8Material property values for the calculation of springs.9 9Calculation formulae .11 9.1Spring work11 9.2S
15、pring Force.11 9.3Spring deflection11 9.4Spring rate11 9.5Torsional stresses.11 9.6Nominal diameter of wire or bar.11 9.7Number of active coils.11 9.8Total number of coils.12 9.9Initial tension force12 10Permissible torsional stress under static or quasi-static loading12 10.1Permissible torsional st
16、ress zul for cold coiled springs 12 10.2Permissible torsional stress zul for hot coiled springs.12 10.3Initial tension torsional stress 0.12 11Calculation of extension springs for dynamic loading13 Annex A (informative) Types of spring ends14 Foreword This European Standard has been prepared by CMC.
17、 This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by June 2002, and conflicting national standards shall be withdrawn at the latest by June 2002. According to the CEN/CENELEC Internal Regulations, the
18、 national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingd
19、om. This European Standard has been prepared by the initiative of the Association of the European Spring Federation ESF and is based on the German Standard DIN 2089-2 - “Helical springs made from round wire and rod; Extension springs; Calculation and design” edition 1992-11, which is known and used
20、in many European countries. 1 Scope This standard specifies the calculation and design of cold and hot coiled helical cylindrical helical extension springs made from round wire and bar with values according to Table 1, loaded in the direction of the spring axis and operating at normal ambient temper
21、atures. Table 1 CharacteristicCold coiled extension springsHot coiled extension springs Wire or bar diameterd 17 mm10 mm d 35 mm Coil diameterD 160 mmD 300 mm Number of active coilsn 3n 3 Spring index4 w 204 w 12 NOTE 1In cases of substantially higher or lower working temperature, it is advisable to
22、 seek the manufacturers advice. NOTE 2Quality Standards for cold coiled extension springs will be developed later. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate pla
23、ces in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication refe
24、rred to applies (including amendments). EN 13906-1, Cylindrical helical springs made from round wire and bar - Calculation and design - Part 1: Compression springs. EN 10270-1:2001, Steel wire for mechanical springs Part 1: Patented cold drawn unalloyed spring steel wire. EN 10270-2:2001, Steel wire
25、 for mechanical springs - Part 2: Oil hardened and tempered spring steel wire. EN 10270-3:2001, Steel wire for mechanical springs - Part 3: Stainless spring steel wire. EN 12166, Copper and copper alloys - Wire for general purposes. EN ISO 2162-1:1996, Technical product documentation - Springs - Par
26、t 1: Simplified representation (ISO 2162-1:1993). EN ISO 2162-3:1996, Technical product documentation - Springs - Part 3: Vocabulary (ISO 2162-3:1993). prEN 10089:1998, Hot-rolled steels for quenched and tempered springs Technical delivery conditions. 3 Terms and definitions, symbols, units and abbr
27、eviated terms 3.1 Terms and definitions For the purposes of this European Standard, the following terms and definitions apply. 3.1.1 spring mechanical device designed to store energy when deflected and to return the equivalent amount of energy when released 2.1 from EN ISO 2162-3:1996 3.1.2 extensio
28、n spring spring that offers resistance to an axial force tending to extend its length, with or without initial tension 2.6 from EN ISO 2162-3:1996 3.1.3 helical extension spring extension spring normally made from wire of circular cross-section wound around an axis with or without spaces between its
29、 coils ( open - or close -wound ) 2.10 from EN ISO 2162-3:1996 NOTEIn the following text of this Standard the term spring is used with the meaning of helical extension spring 3.2 Symbols, units and abbreviated terms Table 2 contains the symbols, units and abbreviated terms used in this standard. Tab
30、le 2 Symbols UnitsTerms 2 ie DD D mmmean diameter of coil Demmoutside diameter of the spring DImminside diameter of the spring Dmmnominal diameter of wire (or bar) EN/mmmodulus of elasticity (or Youngs modulus) FNspring force (including F0) F1, F2Nspring forces, for the spring lengths L1, L2 (at amb
31、ient temperature of 20C) FnNmaximum permissible spring force for the maximum permissible spring length Ln F0Ninitial tension force GN/mmmodulus of rigidity k-stress correction factor (depending on D/d) Lmmspring length L0mmNominal free length of spring L1, L2mmspring lengths for the spring forces F1
32、, F2 LHmmdistance from inner radius of loop to spring body LKmmbody length when unloaded but subject to initial tension force Lnmmmaximum permissible spring length for the spring force Fn mmmhook opening N-Number of cycles up to rupture n-number of active coils nt-total number of coils Table 2 (Conc
33、luded) Symbols UnitsTerms RN/mmspring rate RmN/mmminimum value of tensile strength smmspring deflection s1, s2 .mmspring deflections, for the spring forces F1, F2 shmmdeflection of spring (stroke) between two positions snmmspring deflection, for the spring force Fn WN.mmspring work d D w -spring ind
34、ex kg/dm3Density N/mmuncorrected torsional stress (without the influence of the wire curvature being taken into account) 0 N/mmuncorrected torsional stress, for the initial tension force F0 1, 2 . N/mmuncorrected torsional stress, for the spring forces F1, F2 . k N/mmcorrected torsional stress, (acc
35、ording to the correction factor k) k1, k2 . N/mmcorrected torsional stress, for the spring forces F1, F2 . kh N/mmcorrected torsional stress range, for the stroke sh kn N/mmcorrected torsional stress, for the spring force Fn n N/mmuncorrected torsional stress, for the spring force Fn zul N/mmpermiss
36、ible torsional stress 4 Theoretical extension spring diagram The illustration of the extension spring corresponds to Figure 5.1 from EN ISO 2162-1:1996. The theoretical extension spring diagram is given in Figure 1. Key 1 spring deflection 2 spring lengths Figure 1 Theoretical extension spring diagr
37、am 5 Types of loading NOTEBefore carrying out design calculations it should be specified whether they will be subjected to static loading, quasi- static loading, or dynamic loading. 5.1 Static and/or quasi-static loading A static loading is: a loading constant in time A quasi-static loading is: a lo
38、ading variable with time with a negligibly small torsional stress range ( stroke stress)( e.g. torsional stress range up to 0,1 fatigue strength) a variable loading with greater torsional stress range but only a number of cycles of up to 104 5.2 Dynamic loading In the case of extension springs dynam
39、ic loading is loading variable with time with a number of loading cycles over 104 and torsional stress range greater than 0,1 fatigue strength at: a) constant torsional stress range; b) variable torsional stress range; Depending on the required number of cycles N up to rupture it is necessary to dif
40、ferentiate between two cases as follows: a) infinite life fatigue in which the number of cycles N 107 for cold coiled springs In this case the torsional stress range is lower than the infinite life fatigue limit b) limited life fatigue in which N 107 for cold coiled springs In this case the torsiona
41、l stress range is greater than the infinite life fatigue limit but smaller than the low cycle fatigue limit. In the case of springs with a time- variable torsional stress range and mean torsional stress, (set of torsional stress combinations) the maximum values of which are situated above the infini
42、te fatigue life limit, the service life can be calculated as a rough approximation with the aid of cumulative damage hypotheses. In such circumstances the service life shall be verified by means of a fatigue test. 6 Stress correction factor k The distribution of torsional stresses over the cross sec
43、tion of the wire or bar of a spring is not uniform. The highest torsional stress occurs at the inside coil surface of the spring due to the curvature of the wire or bar (see Figure 2). The maximum torsional stress can be determined by approximation with the aid of a stress correction factor k, which
44、 is dependent on the spring index. The factor shall be taken into account in the calculation of the maximum torsional stress, the minimum torsional stress and torsional stress range of dynamically loaded springs. Its dependency on the spring index can be calculated with the aid of the approximate fo
45、rmula (1), or obtained from Figure 3. Key 1 Spring axis 2 Maximum shear stress 3 Minimum shear stress Figure 2 Distribution of torsional stresses at the surface of the wire or bar Figure 3 Stress correction factor, k , as a function of the spring index, w Approximation formula for the relationship b
46、etween the stress correction factor k and the spring index w is according to Bergstrsser: 750 50 ,w ,w k(1) NOTEAccording to Wahl, an alternatively to formula 1 may also be used, giving approximately the same results: w , w w k 6150 44 14 7 Initial tension force F0 Initial tension force is the force
47、 which shall be applied to the spring in order to overcome the force which presses the coils one against the other. Initial tension force is introduced by winding the coils so that they exert a certain pressure against each other. The initial tension force obtainable in this way is governed primaril
48、y by the quality of the wire, the nominal diameter of the wire d the spring index w and the manufacturing method applied. In addition, the initial tension force depends on the uncorrected maximum permissible torsional stress n (see 10.3) The winding in of initial tension force F0 is only practicable for cold coiled springs which are not given a final annealing heat treatment. Extension springs with initial tension force have their coils pressed tightly together. It may be specified for an extension spring that its coils shall lie loosely in contact with each other without any