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1、BRITISH STANDARD BS EN 20898-7:1995 ISO 898-7: 1992 Mechanical properties of fasteners Part 7: Torsional test and minimum torques for bolts and screws with nominal diameters 1 mm to 10 mm The European Standard EN 20898-7:1995 has the status of a British Standard Licensed Copy: sheffieldun sheffieldu
2、n, na, Wed Nov 01 05:20:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 20898-7:1995 This British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 15 July 1995 BSI 07-1999 The fol
3、lowing BSI references relate to the work on this standard: Committee reference GME/9 Draft for comment 90/80108 DC ISBN 0 580 24385 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee GME/9, Bolts, nuts and accessories, upo
4、n which the following bodies were represented: BEAMA Ltd. British Constructional Steelwork Association Ltd. British Industrial Fasteners Federation British Steel Industry British Steel Industry (Wire Section) Gauge and Tool Makers Association National Association of Fastener Stockholders Society of
5、Motor Manufacturers and Traders Ltd. Washer Manufacturers, Association of Great Britain The following bodies also participated in the preparation of the standard, through subcommittees and panels: British Stainless Steel Association British Turned-parts Manufacturers Association Galvanizers Associat
6、ion Institute of Metal Finishing Metal Finishing Association National Centre of Tribology Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:20:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 20898-7:1995 BSI 07-1999i Contents Page
7、Committees responsibleInside front cover National forewordii Foreword2 1Scope3 2Normative reference3 3Torsional test3 4Minimum breaking torques4 5Evaluation of the torque test4 Annex A (informative) Explanatory note5 Annex ZA (normative) Normative references to international publications with their
8、relevant European publications5 Figure 1 Example of a device for the torsional test3 Table 1 Strength ratio X4 Table 2 Minimum breaking torques4 List of referencesInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:20:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 20898-
9、7:1995 ii BSI 07-1999 National foreword This British Standard has been prepared by Technical Committee GME/9 and is the English language version of EN 20898-7:1995 Mechanical properties of fasteners Part 7: Torsional test and minimum torques for bolts and screws with nominal diameters 1 mm to 10 mm
10、published by the European Committee for Standardization (CEN). It is identical with ISO 898-7:1992, published by the International Organization for Standardization (ISO). EN 20898-7:1995 was produced as a result of international discussions in which the United Kingdom took an active part. A British
11、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. Cross-reference Publication referred toCorrespondin
12、g British Standard ISO 898-1:1988BS EN 20898 Mechanical properties of fasteners Part 1:1992 Specification for bolts, screws and studs Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages 2 to 6, an inside back cover and a back cover.
13、 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 cover. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:20:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME E
14、UROPENNE EUROPISCHE NORM EN 20898-7 January 1995 ICS 21.060.10 Descriptors: Fasteners, breaking torque, bolts, specification, mechanical properties, testing, torsion testing English version Mechanical properties of fasteners Part 7: Torsional test and minimum torques for bolts and screws with nomina
15、l diameters 1 mm to 10 mm (ISO 898-7:1992) Caractristiques mcaniques des lments de fixation Partie 7: Essai de torsion et couples minimaux de rupture des vis de diamtre nominal de filetage de 1 mm 10 mm (ISO 898-7:1992) Mechanische Eigenschaften von Verbindungselementen Teil 7: Torsionsversuch und M
16、indest-Bruchdrehmomente fr Schrauben mit Nenndurchmessern 1 mm bis 10 mm (ISO 898-7:1992) This European Standard was approved by CEN on 1995-01-04. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of
17、 a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A versio
18、n in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greec
19、e, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1995 Copyright reser
20、ved to CEN members Ref. No. EN 20898-7:1995 E Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:20:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 20898-7:1995 BSI 07-1999 2 Foreword This European Standard has been taken over by the Technical Committee CEN/TC 185, Threaded and non-threaded
21、mechanical fasteners and accessories, from the work of ISO/TC 2, Fasteners, of the International Organization for Standardization (ISO). 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 July 1995,
22、and conflicting national standards shall be withdrawn at the latest by July 1995. According to the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg
23、, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, United Kingdom. NOTENormative references to international publications are listed in Annex ZA (normative). Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:20:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 20898-7:1995 BSI 07-19
24、993 1 Scope This part of ISO 898 specifies a torsional test for the determination of the breaking torque of bolts and screws with nominal diameters 1 mm to 10 mm with property classes 8.8 to 12.9 in accordance with ISO 898-1. The test applies to bolts and screws with thread less than M3 for which no
25、 breaking and proof loads are indicated in ISO 898-1, as well as to short bolts and screws with nominal diameters 3 mm to 10 mm which cannot be subjected to a tensile test. The minimum breaking torques are not valid for hexagon socket set screws. 2 Normative reference The following standard contains
26、 provisions which, through reference in this text, constitute provisions of this part of ISO 898. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this part of ISO 898 are encouraged to investigate the possibility
27、of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 898-1:1988, Mechanical properties of fasteners Part 1: Bolts, screws and studs. 3 Torsional test 3.1 Principle Determination of the breaking
28、torque by clamping the bolt or screw to be tested into a test device. 3.2 Apparatus 3.2.1 Test device for torsional test, such as is shown in Figure 1. 3.2.2 Torquemeter, with a scale which shall not exceed to quintuple of the respective minimum breaking torque. The minimum inaccuracy of the torquem
29、eter shall be 7 % of the minimum breaking torque to be tested. 3.3 Test conditions The bolt or screw shall be exclusively subjected to torsion whereby the respective minimum breaking torque according to Table 2 shall be reached before rupture occurs. The test result shall not be influenced by head f
30、riction or by thread friction. Figure 1 Example of a device for the torsional test Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:20:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 20898-7:1995 4 BSI 07-1999 3.4 Procedure Clamp the bolt or screw into the test device over at least two ful
31、l threads, having a free thread length of at least one thread diameter present between the head of the bolt or screw and the threaded insert (see Figure 1). Apply the torque in a continuously increasing manner. 4 Minimum breaking torques The following formula applies to the determination of the mini
32、mum breaking torques: MB min = B min Wp min with and B min = XRm min where 5 Evaluation of the torque test The tested bolt or screw is regarded as having passed the torque test if no rupture occurs before the minimum breaking torques specified in Table 2 are reached. Table 1 Strength ration X Table
33、2 Minimum breaking torques MB minis the minimum breaking torque (see Table 2); Bis the torsional strength; Wpis the polar moment of resistance; d3 minis the minimum value of the minor diameter of the external thread; Rmis the tensile strength; and Xis the strength ratio B/Rm (see Table 1). Wp min ;
34、16 - -d3 min 3 = Property class 8.89.810.912.9 Ratio X0,840,8150,790,75 Thread Pitch mm Minimum breaking torquea MB min Nm Property class 8.89.810.912.9 M10,250,0330,0360,0400,045 M1,20,250,0750,0820,0920,10 M1,40,30,120,130,140,16 M1,60,350,160,180,200,22 M20,40,370,400,450,50 M2,50,450,820,901,01,
35、1 M30,51,51,71,92,1 M3,50,62,42,73,03,3 M40,73,63,94,44,9 M50,87,68,39,310 M6113141617 M7123252831 M81,2533364044 M8 138424652 M101,566728190 M10 18492102114 M10 1,25 758291102 a These minimum breaking torques are valid for bolts and screws with the thread tolerances 6g, 6f and 6e. Licensed Copy: sh
36、effieldun sheffieldun, na, Wed Nov 01 05:20:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 20898-7:1995 BSI 07-19995 Annex A (informative) Explanatory note ISO 898-1 contains property classes for bolts and screws but only indicates minimum breaking loads and proof loads for threads equal to or gre
37、ater than M3 because in the case of smaller bolts and screws the influence of the thread tolerances and the tolerances of the test device is such that an exact determination of breaking loads and proof loads is not possible. Also since bolts and screws with threads greater than M3 up to approximatel
38、y M10 often cannot be subjected to a tensile test (or proof load test) due to their short lengths, minimum breaking torques have been specified for bolts and screws M1 to M10 (including the fine pitch threads M8 1, M10 1 and M10 1,25) which allow an evaluation of the functional properties of the bol
39、ts and screws. For the time being, minimum breaking torques can be specified for property classes 8.8 to 12.9 only, because for lower property classes the test results are widely scattered and therefore more studies are required. The indicated minimum breaking torques are to be applied without takin
40、g account of friction and the type of test device is optional according to this part of ISO 898. Figure 1 is only an example of a suitable test device. The minimum breaking torques have been determined on the basis of cross-sections resulting from the minimum values of the minor diameter of the thre
41、ad tolerance 6g. Tests have shown that the torques can also be used for bolts and screws with thread tolerances 6f and 6e. Annex ZA (normative) Normative references to international publications with their relevant European publications This European Standard incorporates by dated or undated referen
42、ce, provisions from other publications. These normative references are cited at the appropriate places 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 incorporate
43、d in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). PublicationYearTitleENYear ISO 898-11988Mechanical properties of fasteners Part 1: Bolts, screws and studs EN 20898-11991 Licensed Copy: sheffieldun sheffieldun,
44、 na, Wed Nov 01 05:20:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 6 blank Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 01 05:20:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 20898-7:1995 BSI 07-1999 List of references See national foreword. Licensed Copy: sheffieldun sheffieldun, na,
45、Wed Nov 01 05:20:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 20898-7:1995 ISO 898-7: 1992 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europ
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