1、UDC 621 -882.2 : 620.191 DEUTSCHE NORM December 1991 DIN Fasteners Bolts, screws and studs subject to special requirements Surface discontinuities EN 26 157 (IS0 61 57-3 : 1988) (English version of DIN EN 26 157 Part 3) I Part 3 This standard incorporates the English version of Is0 61 57-3. Verbindu
2、ngselemente; Oberflchenfehler; Schrauben fr spezielle Anforderungen (IS0 61 57-3 : 1988) This standard, together with the December 1991 edition of DIN EN 26 157 Part 1, supersedes October 1984 edition of DIN 267 Part 19. .i - 6 C 6 E z r e * L “ C - B E c c z L C I E C C C a f - C 5 3 L s : 7 a r 1
3、E L 7 L t E + C C 2 European Standard EN 26 157-3 : 1991 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 CENTTC 185 to adopt, without alteration, International Standards IS0 6157-1 and
4、IS0 6157-3 as European Standards. The responsible German body involved in its publication is the Norrnenausschu Mechanische Verbindungselemente (Fasteners Standards Committee). Previous to their adoption, the IS0 Standards referred to were in any case applicable for all bolts, screws and studs made
5、to the relevant DIN IS0 Standards. Hence, even without the decision of CEN/TC 185, it would have been necessary to adopt them, in line with the policy of the Normenausschu Mechanische Verbindungselemente providing for the gradual adoption of IS0 product standards as German Standards. DIN EN 26 157 P
6、arts 1 and 3 apply for all bolts, screws and studs covered in existing DIN IS0 Standards and future DIN EN Standards and are also to be implemented in the case of products still manufactured to DIN Standards in which reference is made to DIN 267 Part 19. Unless otherwise agreed, the present standard
7、 applies for bolts, screws and studs of property classes up to 10.9. The specifications given here are less extensive than in DIN 267 Part 19; in particular, there are no specifications with regard to surface discontinuities on the thread, nor are cracks in the head of hexagon socket screws dealt wi
8、th. If the scope of the specifications is deemed inadequate for a given application, then the use of DIN EN 26 157 Part 3 should be agreed. In most respects, DIN EN 26 157 Part 3 corresponds to the October 1984 edition of DIN 267 Part 19, except that it only covers bolts, screws and studs of propert
9、y class 12.9, and applies in cases where it is used by special agreement. The DIN Standards corresponding to the IS0 Standards referred to above and in clause 2 of the EN are as follows: IS0 Standard IS0 898-1 IS0 2859 IS0 3269 IS0 61 57-1 DIN Standard DIN EN 20 898 Part 1 DIN 40 080 DIN IS0 3269 DI
10、N EN 26 157 Part 1 Continued overleaf. EN comprises 15 pages. Beuth Verlag GmbH. Berlin, has the exclusive right of sale for German Standards (DIN-Normen). DIN EN 26 157 P technical delivery conditions; surface discontinuities on bolts, screws and studs Fasteners; surface discontinuities; bolts, scr
11、ews and studs for general requirements Other relevant document Supplement 2 to DIN 918 Fasteners; synopsis of available IS0 Standards and DIN Standards Previous editions DIN 267 Part 19: 05.81, 09.81, 10.84. Amendments In comparison with the October 1984 edition of DIN 267 Part 19, the following ame
12、ndments have been made. a) The scope of the standard has been limited to bolts, screws and studs subject to special requirements. b) The standard now applies only for bolts, screws and studs with a nominal thread diameter of 5 mm or more. c) Specifications regarding forging bursts and shear bursts h
13、ave been amended. International Patent Classification F 16 8 23/00 F 16 i3 35/00 EUROPEAN STANDARD EUROPISCHE NORM NORME EUROPENNE EN 26 157-3 October 1991 UDC 621.882.2 : 620.191 Descriptors: Fasteners, bolts, screws, studs, surface defects. English version Fasteners Part 3: Bolts, screws and studs
14、 for special requirements Surface d iscont nu i t es (IS0 61 57-3 : 1988) Elments de fixation; dfauts de surface. Partie 3: Boulons, vis et goujons pour applications particulires Verbindungselemente; Oberflchenfehler. Teil 3: Schrauben fr besondere Anforde- rungen (IS0 6157-3 : 1988) (IS0 6157-3 : 1
15、988) This European Standard was approved by CEN on 1991-10-10 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 a
16、lteration. 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 version in any other language made by tr
17、anslation under the responsibility of a GEN 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, Luxemb
18、ourg, 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, 8-1050 Brussels O 1991. Copyright reserved to all CEN members. Ref. No
19、. EN 26 157-3: 1991 E Page 2 EN 26 157-3 : 1991 Foreword In 1990, IS0 6157-3 : 1988 was submitted to the CEN PQ procedure. Following the positive result of the PQ, CEN/BT agreed to submit IS0 61 57-3 : 1988 with the following modifications to Formal Vote. In the French version, replace: - boulon by
20、vis, - boulon, vis by vis. 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, Sw
21、itzerland and United Kingdom. Endorsement notice The text of the International Standard IS0 61 57-3 : 1988 was approved by CEN as a European Standard with agreed common modifications as given above. Page 3 EN 26 157-3 : 1991 1 Scope and field of application 1.1 This part of IS0 6157 establishes limi
22、ts for various types of surface discontinuities on bolts, screws and studs for special requirements. It applies to bolts, screws and studs with - - - - property class 12.9; - property classes 8.8, 9.8 and 10.9 when specified in product standards or agreed between supplier and purchaser. nominal thre
23、ad diameters 5 mm and larger; product grades A and B; nominal lenghts / 1Od (or longer if specified); 1.2 Where the permissible limits for surface discontinuities indicated in clause 3 occur, the minimum values for the mechanical and functional properties specified in IS0 898-1 should still be met.
24、When fatigue strength requirements are specified, the fatigue strength should not be lower than that obtained on bolts without defects taken from the same lot. NOTES 1 The figures in clause 3 are examples only. They apply correspond- ingly also to other types of bolts, screws and studs. 2 The indivi
25、dual figures show the surface discontinuities exaggerated in some cases for clarity. 2 References IS0 468, Surface roughness - Parameters, their values and general rules for specifying requirements. IS0 898-1, Mechanical properties of fasteners - Part 7 : Bolts, screws and studs. IC0 2859, Sampling
26、procedures and ia 0,04d,. (with two or more forging bursts, one of which may extend to 0,08d, Depth of forging bursts : 0.04d1) li d = nominal thread diameter !I d,. = head or flange diameter Page 6 EN 26 157-3 1991 3.1.4 Shear bursts Shear bursts may occur, for example during forging, frequently at
27、 the periphery of products having circular or flanged heads, and are located at approximately 45O to the product axis. Shear bursts may also occur on the sides of hexagon head products. Shear bursts ,- Shear bursts Shear burst /- Hexagon head screws Shear burst limits on the wrenching head are as fo
28、llows: Width 0,25 mm + 0,02s1) Depth 0,Md No shear burst in the flats of hexagon bolts and screws shall extend into the crown circle on the top of the head surface (chamfer circle1 or into the underhead bearing surface. Shear bursts, occurring at the intersection of two wrenching flats, shall not re
29、duce the width across corners below the specified minimum. Shear bursts in the raised periphery of indented head bolts and screws shall not exceed a width of 0,06d2) or have a depth extending below the indented portion. Circular head screws Flanges of bolts and screws and peripheries of circular hea
30、d products may have shear bursts, but shall not exceed the following limits : Width of shear bursts: 0,08c3) (for only one shear burst); O,OQd, (with two or more forging shear bursts, one of which may extend to 0,08dc). 1) s = width across flats 2) d = nominal thread diameter 3) d, = head or flange
31、diameter Page 7 EN 26 157-3 : 1991 3.1.5 Forging cracks in socket head screws Cause Appearance Cracks in the periphery, in the top surface and on the indented portion (hexagon socket) may occur on the inner and outer faces due to cut-off of wire section, shear and compressive stress during forging o
32、perations and countersinking of head. 1 Permissible Permissible - Permissible - does not extend more than han the distance between the periphery of the head and the socket Not permissible - connects socket and edge of head Permissible - Not permisible - potential intersecting discontinuities I LNot
33、permissible - potential intersecting discontinuities ,-Permissible Permissibled Permissible /- Not permissible - connects socket and edge of head Page 8 EN 26 157-3 : 1991 Appearance (continued) l -e- Permissible depths : h, 0,03dk1): 0,13 mm max. h2 0,06dk: 1,6 mm max. 1) d, = head diameter Not per
34、missibie - potential intersecting discontinuities of key engagement (bottom of socket) h, / L/ Not permissible - transverse discontinuities in the fillet area 0.3 tL - No cracks permissible Permissible Not permissible - bottom of socket or within 0,31 of bottom of socket 2) I = key engagement socket
35、 depth Page 9 EN 26 157-3 : 1991 Limits Cracks extending from the socket to the outer face and cracks with a traverse indicating a potential to intersect are not permissible. Cracks within 0,3r of the bottom of the socket are not permissible. Cracks located elsewhere in the socket are permissible, p
36、rovided that they do not exceed a length of 0,25r and a depth of 0,03dk (0,13 mm max.). One crack in the iongitudinal direction with a depth not exceeding 0,03dk (0,13 mm max.) at the head/shank intersection and on the top of the head is permissible. Longitudinal cracks with a depth not exceeding 0,
37、06dk (1,6 mm max.) located in the periphery are permissible. 3.2 Raw material seams and laps A seam or lap is a narrow, generally straight or smooth curved line discontinuity running longitudinally on the thread, shank or head. Cause Appearance Seams and laps are inherent in the raw material from wh
38、ich fasteners are made. Lap or seam, usually straight or T- smooth curved line discontinuitv I A - running longitudinally W Lap or seam, usually straight or smooth curved line discontinuiv running longitudinally Limits I Permissible deoth: 0.015d1) + 0.1 mm: 0.4 mm max. .- I If laps or seams extend
39、into the head, they shall not exceed the permissible limits for width and depth specified for bursts (see 3.1.3). I 1) d = nominal thread diameter Page 10 EN 26 157-3 : 1991 3.3 Voids A void is a shallow pocket or hollow on the surface of a bolt or screw due to non-filling of metal during forging or
40、 upsetting. Cause Appearance Voids are produced by marks and impressions due to chips (shear burrs) or by rust formation on the raw material. They are not eliminated during forging or upsetting operations. Voids 1 ,/ I / U Limits I Depth, h, of voids: 1 h 0,02dl): 0,25 mm max. Area of all voids: The
41、 combined surface area of all voids on the bearing face shall not exceed 5 % of the total area. 1 1) d = nominal thread diameter Page 11 EN 26 157-3 : 1991 Limits 3.4 Folds A fold is a doubling over of metal which occurs at the surface of the fastener during forging. from trimming operation1 Tool ma
42、rks produced by machining in the shank, fillet or bearing surface shall not exceed a surface roughness of Ra = 3,2 pm when tested in accordance with IS0 468. Cause Appearance Limits Folds are produced by material displacements due to lack of congruence of forms and volumes of the single forging step
43、s. Permissib at the loaded flank of screw thread below the pitch diameter, even if they start beyond the pitch dia- meter. The following laps are permissible : - - - laps in the crest of the threads of 0,25 H, max.; crest of the threads not entirely rolled out, maximum half a turn on one thread; lap
44、s below the pitch diameter, if they run on the non-loaded flank towards the major diameter and not deeper than 0,25 Hl and not longer than half a turn on one thread. 3.7 Damages Page 13 EN 26 157-3 : 1991 5 P 3 v) 3 m 2- 6 e. O 22C2222222mooSm2P o- o o- o- o- o- o- o- o- o- o- o- o- o- o o- 0- I I i
45、awos 40 qidap x 20 “. 9 9 7- 3 0- Page 14 EN 26 157-3 : 1991 4 Inspection and evaluation procedure For the acceptance inspection procedure, see IS0 3269. Sur- face coatings shall be removed before examination if identifi- cation of the surface discontinuities is impaired. NOTE - The 1984 edition of
46、IS0 3269 gives no specifications on sampling plans for surface discontinuities of fasteners. Until this has been completed, the applicable sampling plan is given in the annex. 4.1 Principles The manufacturer is entitled to use any inspection procedures but due care shall be taken to ensure that prod
47、ucts conform to this part of IS0 615. The purchaser may use the inspection procedure specified in this clause at his acceptance inspection in order to decide whether a lot of fasteners may be accepted or rejected. This procedure shall also be applied when conformance to specifi- cation is disputed,
48、unless some other acceptance procedure has been agreed beniveen the manufacturer and the purchaser at the time of ordering the fasteners. 4.2 Non-destructive testing A random sample shall be taken from the lot in accordance with table 2 in the annex and subjected to either visual tests or other suit
49、able tests, e.g. magnetic techniques or eddy current. If no defective product is found the lot shall be accepted (see also 4.4). If defective products are found these shall form the lot size for the procedures given in 4.3. 4.3 Destructive testing If defective products are detected by the procedures given in 4.2, then a secondary sample shall be taken from the defective products, in accordance with table 3 in the annex, consisting of the products indicating the most serious defects and sectioned at Wo through the discontinuity where the greatest de
