1、BRITISH STANDARD BS EN ISO 6157-2:2004 Fasteners Surface discontinuities Part 2: Nuts The European Standard EN ISO 6157-2:2004 has the status of a British Standard ICS 21.060.20 BS EN ISO 6157-2:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committ
2、ee on 4 August 2004 BSI 4 August 2004 ISBN 0 580 44213 6 National foreword This British Standard is the official English language version of EN ISO 6157-2:2004. It is identical with ISO 6157-2:2004. It supersedes BS EN 493:1992 which is withdrawn. The UK participation in its preparation was entruste
3、d by Technical Committee FME/9, Bolts, nuts and accessories, to Subcommittee FME/9/1, Bolts, nuts, and accessories Materials, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards
4、which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publ
5、ication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible internatio
6、nal/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, an inside front cover, the EN ISO ti
7、tle page, the EN ISO foreword page, the ISO title page, the ISO foreword page, pages 1 to 10, the Annex ZA page and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments EUROPEAN STAND
8、ARD NORME EUROPENNE EUROPISCHE NORM EN ISO 6157-2 July 2004 ICS 21.060.20 Supersedes EN 493:1992 English version Fasteners - Surface discontinuities - Part 2: Nuts (ISO 6157- 2:1995) Elments de fixation - Dfauts de surface - Partie 2: Ecrous (ISO 6157-2:1995) Verbindungselemente - Oberflchenfehler -
9、 Teil 2: Muttern (ISO 6157-2:1995) This European Standard was approved by CEN on 1 July 2004. CEN members are 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-dat
10、e 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
11、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, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
12、Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36
13、B-1050 Brussels 2004 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 6157-2:2004: EI NESO 16-75:22( 400E) 2 Foreword The text of ISO 6157-2:1995 has been prepared by Technical Committee ISO/TC 2 “Fasteners” of the International
14、 Organization for Standardization (ISO) and has been taken over as EN ISO 6157-2:2004 by Technical Committee CEN/TC 185 “Threaded and non-threaded mechanical fasteners and accessories“, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard,
15、either by publication of an identical text or by endorsement, at the latest by January 2005, and conflicting national standards shall be withdrawn at the latest by January 2005. This document supersedes EN 493:1992. According to the CEN/CENELEC Internal Regulations, the national standards organizati
16、ons of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Sloveni
17、a, Spain, Sweden, Switzerland and United Kingdom. Endorsement notice The text of ISO 6157-2:1995 has been approved by CEN as EN ISO 6157-2:2004 without any modifications. NOTE Normative references to International Standards are listed in annex ZA (normative). ENISO61572:2004INTERNATIONAL STANDARD IS
18、O 6157-2 First edition 1995-08-01 Fasteners - Surface discontinuities - Part 2: Nuts l%men ts de fixa tion - Dkfauts de surface - Partie 2: Ecrous Reference number ISO 6157-2:1995(E) ENISO61572:2004OSI )E(5991:2=7516 Foreword ISO (the International Organization for Standardization) is a worldwide fe
19、deration of national Standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Esch member body interested in a subject for which a technical committee has been established has the right to be represented on that com
20、mittee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the
21、technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 6157-2 was prepared by Technical Committee ISO/TC 2, Fasteners, Subcommittee SC 1, Mechanic
22、al properties of fasteners. ISO 6157 consists of the following Parts, under the general title Fasteners - Surface discon tinuities: - Part 1: Bolts, screws and studs for general requiremen ts - Part 2: Nuts - Part 3: Bolts, screws and studs for special requiremen ts 0 OSI 5991 llA sthgir .devreser s
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24、1 eveneG 02 l dnalreztiwS detnirP ni dnalreztiwS ii ENISO61572:2004LANOITANRETNI DRADNATS 0 OSI OSI )E(5991:2=7516 Fasteners - Surface discontinuities - Part 2: Nuts 1 Scope This part of ISO 6157 establishes limits for various types of surface discontinuities on nuts. lt applies to nuts with - nomin
25、al thread diameters from 5 mm up to and including 39 mm; - product grades A and B; - all property classes according to ISO 898-2 and ISO 898-6, unless otherwise specified in product Standards or agreed between supplier and purchaser. 2 Normative references The following Standards contain provisions
26、which, through reference in this text, constitute provisions of this part of ISO 6157. At the time of publication, the editions indicated were valid. All Standards are subject to revision, and Parties to agreements based on this part of ISO 6157 are encouraged to investigate the possibility of apply
27、ing the most recent editions of the Standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 468:1982, Surface roughness - Parameters, their values and general rules for specifying requirements. ISO 898-2: 1992, Mechanical properties of fas
28、teners - Part 2: Nuts with specified proof load values - Coarse thread. ISO 898-6: 1994, Mechanical properties of fasteners - Part 6: Nuts with specified proof load values - Fine pitch thread. ISO 2320:1983, Prevailing torque type steel hexagon nuts - Mechanical and Performance properties. ISO 3269:
29、 1988, Fasteners - Acceptance inspection. ISO 10484: -1, Widening test on nuts. ISO 10485:1991, Cone proof load test on nuts. 1) To be published. 1 ENISO61572:20043 Types, Causes, appearance and limits of surface discontinuities Even if the permissible limits for surface discontinuities indicated in
30、 this clause occur, the minimum values for the mechanical and functional properties specified in ISO 898-2, ISO 898-6 and ISO 2320, as appropriate, shall still be met. In addition, the dimensional requirements of the appropriate product Standard shall be satisfied. NOTES 1 The figures in this clause
31、 are examples only; they also apply correspondingly to other types of nuts. 2 The individual figures show the surface discontinuities exaggerated in some cases for clarity. 3.1 Cracks A Crack is a clean (crystalline) fracture passing through or across the grain boundaries and may possibly follow inc
32、lusions of foreign elements. Cracks are normally caused by overstressing the metal during forging or other forming operations, or during heat treatment, or may have been present in the raw material. Where Parts are subjected to significant reheating, Cracks are usually discoloured by scale. 3.1 .l Q
33、uench Cracks Quench Crack ENISO61572:20040 OSI OSI )E(5991:2=7516 3.1.2 Forging Cracks and inclusion Cracks face, or in thread, caused - there are not more than two forging Cracks which extend across the full width of the bearing face, neither of which shall exceed a depth of 0,05d; - no Crack exten
34、ds into the tapped hole beyond the first full thread; - no Crack in the first full thread exceeds a depth of 0,5H,; is the nominal thread diameter; is the diameter of the bearing face; is the effective thread height H, = 0,541P where P is the pitch of the thread; S is the width across flats. In the
35、case of nuts with a flange, Cracks in the area between s and d, shall not be permitted. 3 ENISO61572:2004OSI )E(5991:2=7516 0 OSI 3.1.3 Cracks in the locking element of all-metal prevailing torque type nuts Cause Appearance Limits Cracks in the locking element of all-metal prevailing torque type nut
36、s may occur during the Cut-off, forging or deflecting process, and are either on the external or internal face. Internal Cracks Extemal Cracks Cracks in the locking element resulting from the forging process shall be permitted, provided that all mechanical and functional requirements are met and tha
37、t - there are not more than two Cracks which extend the full width of the crown circle, neither of which shall exceed a depth of 0,05d; - no Crack extends into the tapped hole beyond the first full thread; - no Crack in the first full thread exceeds a depth of 0,5H,; where d Hl is the nominal thread
38、 diameter; is as defined in 3.1.2. Cracks in the locking element resulting from the deflecting process shall not be permitted. 3.1.4 Cracks in the washer retainer of nuts with captive washers A Crack in the washer retainer is an opening in a lip or hub of metal used for securing a washer on a nut. C
39、ause Washer-retainer Cracks may occur when pressure is applied to the lip or hub during assembly of the washer. Appearance Limits r Washer-retainer Cracks Washer-retainer Cracks are permissible if limited to the contour of the lip or hub used for retaining purposes, provided that the washer is secur
40、ely held and able to rotate freely. ENISO61572:20040 OSI OSI )E(5991:2=7516 3.2 Shear bursts Shear bursts are open breaks in the surface of the metal. Shear bursts at the periphery of the flange of nuts with a flange are allowed, providing they do not extend 5 ENISO61572:2004OSI )E(5991:2=7516 3.3 B
41、ursts Bursts are open breaks in the surface of the metal. crown circle (see 3.4) but not the burst. Bursts occurring at the intersection of two wrenching flats shall not reduce the width across corners below the specified minimum value. No burst or shear burst located at the intersection of the top
42、or bottom face with a wrenching flat shall have a width greater than (0,25 + 0,02s) mm, where s is the width across flats. Bursts and shear bursts at the peripher-y of the flange of nuts with a flange are allowed, provided that they do not extend into the minimum diameter of the bearing face, dw, an
43、d that the width of the hurst does not exceed 0,08d, where d, is the flange diameter. 6 ENISO61572:20040 OSI ISO 6157=2:1995(E) 3.4 Seams A seam is a longitudinal surface discontinuity in the form of an unwelded open fold in the material. Cause Appearance Seams are usually inherent in the raw materi
44、al from which fasteners are made. I I Seams shall be permitted, provided that a depth from the surface of 0,05d for all thread sizes is not ex- ceeded, where d is the nominal thread diameter. Limits 3.5 Felds A fold is a doubling over of metal which occurs at the surface of the nut during forging. C
45、ause Appearance Limits Folds may be produced by material displacements during forging operations on nuts at or near the inter- section of diameter changes, or on the top or bottom face of the nut. Fold on top or r bottom face L- Feld on side L Folds I Folds / Fold at periphery of bearing face of fla
46、nge nuts Folds are permitted, but those located at the intersection of the flange peripher-y and bearing face of nuts with a flange shall not intrude into the bearing surface. 7 ENISO61572:2004OSI )E(5991:2=7516 0 OSI 3.6 Voids A void is a shallow pocket or hollow on the surface of a nut caused by n
47、on-filling of metal during forging or up- setting. Cause Appearance Limits Voids are produced by marks or impressions of Chips (shear burrs) or by rust formation on the raw material. They are not planished during forging or upsetting operations. Depth, h, of voids: h 24 mm. 8 ENISO61572:20040 OSI OS
48、I )E(5991:2-7516 3.7 Tool marks Tool marks are longitudinal or circumferential grooves of shallow depth. Cause Appearance Limits Tool marks are produced by relative motions between the work piece and the manufacturing tool. Tool marks are most frequently elongated or circumferential. L- Tool marks P
49、ermissi ble tool marks Tool marks on the bearing surface shall not exceed a surface roughness of R, = 3,2 Pm when tested in ac- cordante with ISO 468. Tool marks on other surfaces are allowed. 3.8 Damages Damages are indentations of any surface of a nut. I Cause Appearance Limits r Damages, for example dents, scrapes, nicks and gouges, are produced by external actions during handling and transport. Damages have no precise geometrical shape, location or direct
