ISO-6157-1-1988.pdf
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1、INTERNATIONAL STANDARD INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEXflYHAPOAHAR OPrAHM3AMR l-l0 CTAHAAPTM3ALWl Fasteners - Surface discontinuities - Part 1: Bolts, screws and studs for general requirements h5ments de fixation - Dhfaots de surface - P
2、artie 1: Boulons, vis et goujons dusage gh5ral IS0 6157-l First edition 1988-08-01 Reference number 1 IS0 6157-1: 1988 (E) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:15:5
3、4 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 61!57-1 : 1966 (E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies US0 member bodies). The work of preparing International Standards is normally ca
4、rried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO, also take part in the wo
5、rk. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standa
6、rds by the IS0 Council. They are approved in accordance with IS0 procedures requiring at least 75 % approval by the member bodies voting. International Standard IS0 6157-1 was prepared by Technical Committee ISO/TC 2, Fasteners. Users should note that all International Standards undergo revision fro
7、m time to time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated. tnternational Organization for Standardization, l!Hfl 0 Printed in Switzerlind Copyright International Organization for Standardization Provided by IHS under lic
8、ense with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:15:54 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD IS0 6167-I : 1966 (EI Fasteners - Surface discontinuities - Part 1: Bolts, screws and studs for general re
9、quirements 1 Scope and field of application 1.1 This part of IS0 6157 establishes limits for various types of surface discontinuities on bolts, screws and studs for general requirements. It applies to bolts, screws and studs with - nominal thread diameters 5 mm and larger; - product grades A and B;
10、- property classes up to and including 10.9, unless other- wise specified in product standards or agreed between supplier and purchaser. 1.2 Limits for surface discontinuities on bolts, screws and studs for special requirements (e.g. automatic assembly) are laid down in IS0 6157-3. When the engineer
11、ing requirements of the application necessitate that surface discontinuities on bolts, screws and studs be more closely controlled, it should be specified in the respective product standard, or the purchaser shall specify the applicable limits in the inquiry and purchase order. 1.3 Where the permiss
12、ible limits for surface discontinuities indicated in clause 3 occur, the minimum values for the mechanical and functional properties specified in IS0 696-l should still be met. NOTES 1 The figures in clause 3 are examples only. They apply correspond- ingly also to other types of bolts, screws and st
13、uds. 2 The individual figures show the surface discontinuities exaggerated in some cases for clarity. 2 References IS0 466, Surface roughness - Parameters, their values and general rules for specifying requirements. IS0 898-1, Mechanical properties of fasteners - Part 1: Bolts, screws and studs. IS0
14、 2659, Sampling procedures and tables for inspection by attributes. IS0 3269, Fasteners - Acceptance inspection. 3 Types, causes, appearance and limits of surface discontinuities 3.1 Cracks A crack is a clean (crystalline) fracture passing through or across the grain boundaries and may possibly foll
15、ow inclusions of foreign elements. Cracks are normally caused by overstress- ing the metal during forging or other forming operations, or during heat treatment. Where parts are subjected to significant reheating, cracks usually are discoloured by scale. Copyright International Organization for Stand
16、ardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:15:54 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 6157-I : 1666 (EI 3.1.1 Quench cracks Cause Appearance Limits Quench cracks of any depth,
17、 any length, or in any location are not permitted. Quench cracks may occur during hardening due to excessively high thermal and transformation stresses. Quench cracks usually follow an irrenular and erratic course on the surface of the fastener. Quench crack across top Quench crack circum- erential
18、and adjacent of head. Usually an Quench crack extension of crack in at corner of head Quench crack at root Quench crack across washer face and to depth of washer face thickness Quench crack extending radially into fillet Quench at root Quench crack 3.1.2 Forging cracks Cause Appearance Forging crack
19、s may occur during the cut-off or forging operations and are located on the top of the head of screws and bolts and on the raised periphery of indented head bolts and screws. Limits Length, I, of forging cracks : 1 Forging bursts =e Forging bursts Limits Hexagon head screws No forging burst in the f
20、lats of hexagon bolts and screws shall extend into the crown circle on the top of the head surface (chamfer circle) or into the underhead bearing surface. Forging bursfs occurring at the intersection of two wrenching flats shall not reduce the width across corners below the specified minimum. Forgin
21、g bursts in the raised periphery of indented head bolts and screws shall not exceed a width of 0,06dl) or have a depth extending below the indented portion. Circular head screws Flanges of bolts and screws and peripheries of circular head screws may have forging bursts, but they shall not exceed the
22、 following limits : Width of forging bursts: 0,08dC2) (with only one forging burst); 0,04d, (with two or more forging bursts, one of which may extend to 0,08dJ. 1) d = nominal thread diameter 2) d, = head or flange diameter 3 Copyright International Organization for Standardization Provided by IHS u
23、nder license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:15:54 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO6167-1:1666(E) 3.1.4 Shear bursts Cause Appearance Limits Shear bursts may occur, for example during forging, frequent
24、ly at the periphery of products having circular or flanged heads, and are located at approximately 4!5O to the product axis. Shear bursts may also occur on the sides of hexagon head products. S/hear bursts l - /-Shear bursts I- Shear burst Hexagon head screws No shear burst in the flats of hexagon b
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