1、DEUTSCHE NORM April 1995 DIN Mechanical properties of fasteners Torsional test and minimum torques for bolts and screws with nominal diameters 1 mrn to 10 rnm English version (IS0 898-7 of DIN 1992) EN 20898-7 IEN 20 898-i This standard incorporates the English version of Is0 898-7. ICS21.060.10 Sup
2、ersedes DIN 267-25, November 1984 edition. Descriptors: Fasteners, bolts, screws, mechanical properties, testing. Mechanische Eigenschaften von Verbindungselementen. Teil 7: Torsionsversuch und Mindest-Bruchdrehmomente fr Schrauben mit Nenndurchmessern 1 mm bis 10 mm (IS0 898-7: 1992) European Stand
3、ard EN 20898-7:1995 has the status of a DIN Standard. A comma is used as the decimal marker. National foreword This standard has been published in accordance with a decision taken by CEN/185 to adopt International Standard IS0 898-7 as a European Standard. The responsible German body involved in its
4、 preparation was the Normenausschu Mechanische Verbindungslemente (Fasteners Standards Committee). DIN EN 20898-1 is the standard corresponding to International Standard IS0 898-1 referred to in clause 2. Amendments In comparison with DIN 267-25, November 1984 edition, the following amendments have
5、been made. a) The scope of the torsional test has been limited to cover only bolts and screws of property classes 8.8 to 12.9. b) The minimum breaking torque has been changed for property class 12.9 bolts and screws with MI O x 1 thread and property classes 8.8, 10.9 and 12.9 bolts and screws with M
6、lOx 1,25 thread. c) For property class 9.8 bolts and screws, additional minimum breaking torque values have been specified. Previous edition DIN 267-25: 1984-1 1. Standard referred to (and not included in Normative reference and Annex ZA): DIN EN 20898-1 Mechanical properties of fasteners: bolts, sc
7、rews and studs (IS0 898-1 : 1988) EN comprises 6 pages. ith Verlag GmbH, Berlin, has the exclusive right of sale for German Standards (DIN-Normen). DIN EN 20898-7 Engl. Price group 09.95 Sales No. 1106 EUROPEAN STANDARD NORME EUROPENNE EUROPAISCHE NORM EN 20898-7 January 1995 ICs 21.060.10 Descripto
8、rs: Fasteners, bolts, screws, mechanical properties, testing. English version Mechanical properties of fasteners Part 7: Torsional test and minimum torques for bolts and screws with nominal diameters 1 mm to 10 mm (IS0 898-7 1992) Caractristiques mcaniques des l- ments de fixation. Partie 7: Essai d
9、e tor- sion et couples minimaux de rupture des vis de diamtre nominal de filetage de 1 mm 10mm (60898-7:1992) Mechanische Eigenschaften von Verbin- dungselementen. Teil 7: Torsionsversuch und Mindest-Bruchdrehmomente fr Schrauben mit Nenndurchmessern 1 mm bis 1 O mm (IS0 898-7 : 1992) This European
10、Standard was approved by CEN on 1995-01-04 and is identical to the IS0 Standard as referred to. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-da
11、te 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 version in any other language made by translation under the
12、 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, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands,
13、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, 6-1050 Brussels Q 1995. Copyright reserved to all CEN members. Ref. No. EN 20898-7: 1995
14、E Page 2 EN 20898-7:1995 Foreword International Standard IS0 898-7: 1992 Mechanical properties of fasteners; torsional test and minimum torques for bolts and screws with nominal diameters 1 mm to 10 mm, which was prepared by ISOTTC 2 Fasteners of the International Organization for Standardization, h
15、as been adopted by Technical Committee CENTTC 185 Threaded and non-threaded mechanical fasteners and accessories. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, and conflicting national standards withdrawn, by Ju
16、ly 1995 at the latest. In accordance with the CENKENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switze
17、rland and United Kingdom. Endorsement notice The text of the International Standard IS0 898-7 : 1992 was approved by CEN as a European Standard without any modifi- cation. NOTE: Normative references to international publications are listed in Annex ZA. 1 Scope This part of IS0 898 specifies a torsio
18、nal test for lhe delermination of the breaking torque of bolts and screws with nominal diameters 1 mm to 10 rnm with property classes 8.8 to 12.9 in accordance with IS0 898-1. The test applies to bolts and screws with thread less than M3 for which no breaking and proof loads are indicated in IS0 898
19、-1, as well as to short bolts and screws with nominal diameters 3 mm to 10 rnrn which cannot be subjected to a tensile test. The minimum breaking torques are not valid for hexagon socket set screws. Page 3 EN 20 898-7 : 1995 3.2 Apparatus 2 Normative reference The following standard contains provisi
20、ons which, through reference in this text, constitute provisions of this part of IS0 898. At the time of publication, the edition indicated was valid. All standards are sub- ject to revision, and parties to agreements based on this part of IS0 898 are encouraged to investigate the possibility of app
21、lying the most recent edition of the standard indicated below. Members of IEC and IC0 maintain registers of currently valid Inter- national Standards. IS0 898-1 :I 988, Mechanical properties of fasteners - Part I: Bolts, screws and studs. 3 Torsional test 3.1 Principle Deterniination of the breaking
22、 torque by clamping the bolt or screw to be tested into a test device. 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 ex- ceed the quintuple of the respective minimum breaking torque. The maximum inaccuracy of the torquemeter shall
23、 be f ing torque to be tested. 3.3 Test conditions The bolt or screw shall 7 o/o of the minimum break- 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 influ- enced by head fri
24、ction or by thread friction. 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 I). Apply the torque in a continuously
25、 in- creasing man ner. Page 4 EN 20 898-7 : 1995 4 Minimum breaklng torques The following formula applies to the determination of the minimum breaking torques: MB niin = TB min.J+p niin with ?l “p niin = 16 .d,“ min and TB inin = X.Rm niin where MBmin is the minimum breaking torque (see table 2); is
26、 the torsional strength; is the polar moment o resistance; is the minimum value of the minor di- ameter of the external thread; is the tensile strength; and is the strength ratio T/R, (see table 1). 5 Evaluation of the torque test The tested bolt or screw is regarded as having passed the torque test
27、 if no rupture occurs before the minimum breaking torques specified in table 2 are reached. Figure 1 - Example of a device for the torsional test Page 5 EN 20 898-7 : 1995 Pitch mm Table 1 - Strength ratio X Minimum breaking torqc) MB min Nm I Property class 1 8.8 I 9.8 I 10.9 I 12.9 I M1 M1,2 M1,4
28、M1,B Y2 I Ratio X 1 0.84 1 0,815 I 0.79 1 0,75 I 0,25 0,033 0,036 0,040 0,045 0,25 0,075 0,082 0,092 0.10 0.3 0.12 0,13 0,14 0,16 0.35 0,16 0,18 0,20 0,22 0,4 0,37 0,40 0,45 0,50 Table 2 - Minimum breaking torques 38 66 84 75 42 46 52 72 81 90 92 102 114 82 91 102 Thread Property class 8.8 9.8 10.9
29、12.9 0,13 0,14 0,16 0,37 0,40 0,45 0,50 , P;Tclass I 0,35 I I I I M2, I 0,45 I 0,82 I 0,90 I 1,0 I 1,l M8 x 1 M10 - M10 x 1 M10 x 1,25 - I I I 1 I I) These minimum breaking torqiies ate valid for bolts and screws with the thread tolerances 69, 6f and 6e. Page 6 EN 20898-711995 Annex A (informative)
30、Explanatory note IS0 898-1 contains property classes for bolts and screws but only 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 toler- ances of the test device i
31、s such that an exact deter- mination of breaking loads and proof loads is not pos si ble. Also since bolts and screws with threads greater than M3 up to approximately MIO often cannot be subjected to a tensile test (or proof load test) due to their short lengths, minimum breaking torques have been s
32、pecified for bolts and screws MI to MIO (in- cluding the fine pitch threads M8 x 1. MIO x 1 and MIO x 125) which allow an evaluation of the func- tional properties of the bolts and screws. For the time being, minimum breaking torques can be specified for property classes 8.8 to 12.9 only, be- cause
33、for lower property classes the test results are widely scattered and therefore more studies are re- quired. 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 pari of IS0 898. Figure 1 is only an examp
34、le of a suitable test device. The minimum breaking torques have been deter- mined on the basis of cross-sections resulting from the minimum values of the minor diameter of the thread tolerance 6g. Tests have shown that the torques can also be used for bolts and screws with thread tolerances 6f and 6
35、e. Annex ZA (normative) Normative references to international publications with their relevant European publications 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 t
36、he 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 referred to applies (including amendments). Publication - Year Title - EN - Year IS0 898-1 1988 Mechanical properties of fasteners - Part 1 : Bolts, screws and studs EN 20898-1 1991
