1、BRITISH STANDARD BS EN 20898-7:1995 ISO898-7: 1992 Mechanical properties of fasteners Part7: Torsional test and minimum torques for bolts and screws with nominal diameters1mmto10mm The European Standard EN20898-7:1995 has the status of a British StandardBSEN20898-7:1995 This British Standard, having
2、 been prepared under the directionof the Engineering SectorBoard, was published underthe authority of the Standards Board and comes into effect on 15 July1995 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference GME/9 Draft for comment 90/80108 DC ISBN 0
3、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, upon which the following bodies were represented: BEAMA Ltd. British Constructional Steelwork Association Ltd. British Indust
4、rial Fasteners Federation British Steel Industry British Steel Industry (Wire Section) Gauge and Tool Makers Association National Association of Fastener Stockholders Society of Motor Manufacturers and Traders Ltd. Washer Manufacturers, Association of Great Britain The following bodies also particip
5、ated in the preparation of the standard, through subcommittees and panels: British Stainless Steel Association British Turned-parts Manufacturers Association Galvanizers Association Institute of Metal Finishing Metal Finishing Association National Centre of Tribology Amendments issued since publicat
6、ion Amd. No. Date CommentsBSEN20898-7:1995 BSI 07-1999 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 1 Scope 3 2 Normative reference 3 3 Torsional test 3 4 Minimum breaking torques 4 5 Evaluation of the torque test 4 Annex A (informative) Explanatory note
7、5 Annex ZA (normative) Normative references to international publications with their relevant European publications 5 Figure 1 Example of a device for the torsional test 3 Table 1 Strength ratio X 4 Table 2 Minimum breaking torques 4 List of references Inside back coverBSEN20898-7:1995 ii BSI 07-199
8、9 National foreword This British Standard has been prepared by Technical Committee GME/9 and is the English language version of EN20898-7:1995 Mechanical properties of fasteners Part7: Torsional test and minimum torques for bolts and screws with nominal diameters1mmto10mm published by the European C
9、ommittee for Standardization (CEN). It is identical with ISO898-7:1992, published by the International Organization for Standardization (ISO). EN20898-7:1995 was produced as a result of international discussions in which the United Kingdom took an active part. A British Standard does not purport to
10、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 to Corresponding British Standard ISO898-1:
11、1988 BS EN20898 Mechanical properties of fasteners Part1:1992 Specification for bolts, screws and studs Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theEN title page, pages2 to6, an inside back cover and a back cover. This standard has been updated (se
12、e copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN20898-7 January 1995 ICS 21.060.10 Descriptors: Fasteners, breaking torque, bolts,specification, mechanical properti
13、es, testing, torsion testing English version Mechanical properties of fasteners Part7: Torsional test and minimum torques for bolts and screws with nominal diameters1mm to10mm (ISO898-7:1992) Caractristiques mcaniques des lments de fixation Partie7: Essai de torsion et couples minimaux de rupture de
14、s vis de diamtre nominal de filetage de1mm10mm (ISO898-7:1992) Mechanische Eigenschaften von Verbindungselementen Teil7: Torsionsversuch und Mindest-Bruchdrehmomente fr Schrauben mit Nenndurchmessern1mm bis10mm (ISO898-7:1992) This European Standard was approved by CEN on 1995-01-04. CEN members are
15、 bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard 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 t
16、he Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version 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 sta
17、tus as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Co
18、mit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1995 Copyright reserved to CEN members Ref. No. EN20898-7:1995 EEN20898-7:1995 BSI 07-1999 2 Foreword This European Standard has been taken over by the Technical Committee CEN/TC185,
19、Threaded and non-threaded mechanical fasteners and accessories, from the work of ISO/TC2, 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
20、the latest by July1995, and conflicting national standards shall be withdrawn at the latest by July1995. 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, Ire
21、land, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, United Kingdom. NOTENormative references to international publications are listed in Annex ZA (normative).EN20898-7:1995 BSI 07-1999 3 1 Scope This part of ISO898 specifies a torsional test for the determination of t
22、he breaking torque of bolts and screws with nominal diameters1mmto10mm with property classes8.8to12.9in accordance with ISO898-1. The test applies to bolts and screws with thread less than M3 for which no breaking and proof loads are indicated in ISO898-1, as well as to short bolts and screws with n
23、ominal diameters 3mm to10mm 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 provisions which, through reference in this text, constitute provisions of this part of ISO898. At
24、the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this part of ISO898 are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain r
25、egisters of currently valid International Standards. ISO898-1:1988, Mechanical properties of fasteners Part1: Bolts, screws and studs. 3 Torsional test 3.1 Principle Determination of the breaking torque by clamping the bolt or screw to be tested into a test device. 3.2 Apparatus 3.2.1 Test device fo
26、r 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 torquemeter shall be 7% of the minimum breaking torque to be tested. 3.3 Test conditions The bolt or screw shal
27、l 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 friction or by thread friction. Figure 1 Example of a device for the torsional testEN20898-7:1995 4 BSI 07
28、-1999 3.4 Procedure Clamp the bolt or screw into the test device over at least two full 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 M
29、inimum breaking torques The following formula applies to the determination of the minimum breaking torques: M B min= B minW p min with and B min= XR m 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 minim
30、um breaking torques specified in Table 2 are reached. Table 1 Strength ration X Table 2 Minimum breaking torques M B min is the minimum breaking torque (see Table 2); B is the torsional strength; W p is the polar moment of resistance; d 3 min is the minimum value of the minor diameter of the externa
31、l thread; R m is the tensile strength; and X is the strength ratio B /R m(see Table 1). W p min;16 -d 3 min 3 = Property class 8.8 9.8 10.9 12.9 Ratio X 0,84 0,815 0,79 0,75 Thread Pitch mm Minimum breaking torque a M B min Nm Property class 8.8 9.8 10.9 12.9 M1 0,25 0,033 0,036 0,040 0,045 M1,2 0,2
32、5 0,075 0,082 0,092 0,10 M1,4 0,3 0,12 0,13 0,14 0,16 M1,6 0,35 0,16 0,18 0,20 0,22 M2 0,4 0,37 0,40 0,45 0,50 M2,5 0,45 0,82 0,90 1,0 1,1 M3 0,5 1,5 1,7 1,9 2,1 M3,5 0,6 2,4 2,7 3,0 3,3 M4 0,7 3,6 3,9 4,4 4,9 M5 0,8 7,6 8,3 9,3 10 M6 1 13 14 16 17 M7 1 23 25 28 31 M8 1,25 33 36 40 44 M8 1 38 42 46
33、52 M10 1,5 66 72 81 90 M10 1 84 92 102 114 M10 1,25 75 82 91 102 a These minimum breaking torques are valid for bolts and screws with the thread tolerances6g,6f and6e.EN20898-7:1995 BSI 07-1999 5 Annex A (informative) Explanatory note ISO898-1 contains property classes for bolts and screws but only
34、indicates minimum breaking loads and proof loads for threads equal to or greater 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.
35、 Also since bolts and screws with threads greater than M3 up to approximatelyM10often 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 M
36、10 1,25) which allow an evaluation of the functional properties of the bolts and screws. For the time being, minimum breaking torques can be specified for property classes8.8 to12.9 only, because for lower property classes the test results are widely scattered and therefore more studies are required
37、. The indicated minimum breaking torques are to be applied without taking account of friction and the type of test device is optional according to this part of ISO898. Figure 1 is only an example of a suitable test device. The minimum breaking torques have been determined on the basis of cross-secti
38、ons resulting from the minimum values of the minor diameter of the thread tolerance6g. Tests have shown that the torques can also be used for bolts and screws with thread tolerances6f and6e. Annex ZA (normative) Normative references to international publications with their relevant European publicat
39、ions This European Standard incorporates by dated or undated reference, 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 thes
40、e publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). Publication Year Title EN Year ISO898-1 1988 Mechanical properties of fasteners Part1: Bolts,
41、 screwsand studs EN20898-1 19916 blankBSEN20898-7:1995 BSI 07-1999 List of references See national foreword.BS EN 20898-7:1995 ISO898-7: 1992 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It pr
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