1、BS 1580-1:2007Unified screw threadsPart 1: Screw threads with diameters in and larger RequirementsICS 21.040.2014-NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDIncorporating Corrigendum No.1Publishing and copyright informationThe BSI copyright notice displayed
2、 in this document indicates when the document was last issued. BSI 200ISBN 978 0 580 68654 2The following BSI references relate to the work on this standard: Committee reference FME/9 Draft for comment 07/30158490 DCPublication historyFirst published June 1949 Second edition, November 1953 Third edi
3、tion, as Parts 1 and 2, September 1962 Fourth edition, as Part 1, December 2007Amendments issued since publicationAmd. no. Date Text affectedBS 1580-1:20079C1 Table 2Size: 12 20Class: 3AColumn: 10 Correction: 0.458 7 corrected to0.438 7Size: 1916 6Class: 2AColumn: 11 Correction: 1.355 4 corrected to
4、1.335 4Size: 312 16Class: 3AColumn: 9 Correction: 0.004 8 corrected to0.004 3Size: 558 12 and 558 16Column: 12 Correction: 23 corrected to 2B in two placesTable 31 Column: 1, second value Correction: 38 corrected to 36Figure D.1aDimension frnaddedBibliography Reference to BS 84 addedAugust 2009 BSI
5、2009 iBS 1580-1:2007ContentsForeword ivSection 1: General 11 Scope 12 Normative references 23 Terms and definitions and symbols 24 Profile of unified screw threads 3Section 2: Standard series 95 Diameter/pitch combinations 96 Tolerance classes of external and internal threads 97 Limits of size, and
6、tolerances, for uncoated threads 98 Allowances for uncoated threads 109 Coated threads 1110 Gauges 1411 Designation of unified screw threads 16Section 3: Special series (UNS) 6912 Diameter/pitch combinations, fractional sizes 6913 Diameter/pitch combinations, decimal sizes 7014 Tolerance classes of
7、external and internal UNS threads 7015 Tolerances and allowances 7016 Coated UNS threads 7117 Designation of UNS threads 71AnnexesAnnex A (informative) Bases of tolerances and allowances for unified screw threads in and larger 89Annex B (informative) Outline guide, and examples, for calculating limi
8、ts of size of untabulated UNS screw threads 95Annex C (informative) Forms of the crest of external threads 101Annex D (informative) General symbols 103Annex E (informative) Tolerances on pitch and flank angle in relation to tolerance on effective diameter 106Annex F (informative) Standard unified th
9、read series, guidance on selection and use 108Annex G (informative) Standard unified thread series, information and guidance regarding the tolerance classes 109Bibliography 111List of figuresFigure 1 Basic profile of unified screw threads 5Figure 2 Design profiles of unified internal and external th
10、reads (maximum material condition) 6Figure 3 Limiting profiles for crests of external threads 8Figure 4 Classes of unified screw threads Effective diameter tolerance zones of finished uncoated threads 12Figure 5 Classes of unified screw threads Effective diameter tolerance zones of coated threads be
11、fore and after coating 13Figure 6 Tolerance zones for unified threads, Class 1A external thread and Class 1B internal thread 14Figure 7 Tolerance zones for unified threads, Class 2A external thread and Class 2B internal thread 15Figure 8 Tolerance zones for unified threads, Class 3A external thread
12、and Class 3B internal thread 1614-BS 1580-1:2007ii BSI 2009Figure A.1 Unified screw threads Nomogram for effective (pitch) diameter tolerances, Class 2A 94Figure C.1 Crest profiles on external threads resulting from different production methods 102Figure D.1 General symbols 105List of tablesTable 1
13、Unified screw threads, standard series 20Table 2 Unified screw threads, standard series Limits of size 22Table 3 Coarse thread series (UNC) Limits and tolerances for finished uncoated threads External threads Class 1A 48Table 4 Coarse thread series (UNC) Limits and tolerances for finished uncoated t
14、hreads Internal threads Class 1B 49Table 5 Coarse thread series (UNC) Limits and tolerances for finished uncoated threads External threads Class 2A 50Table 6 Coarse thread series (UNC) Limits and tolerances for finished uncoated threads Internal threads Class 2B 51Table 7 Coarse thread series (UNC)
15、Limits and tolerances for finished uncoated threads External threads Class 3A 52Table 8 Coarse thread series (UNC) Limits and tolerances for finished uncoated threads Internal threads Class 3B 53Table 9 Fine thread series (UNF) Limits and tolerances for finished uncoated threads External threads Cla
16、ss 1A 54Table 10 Fine thread series (UNF) Limits and tolerances for finished uncoated threads Internal threads Class 1B 54Table 11 Fine thread series (UNF) Limits and tolerances for finished uncoated threads External threads Class 2A 55Table 12 Fine thread series (UNF) Limits and tolerances for fini
17、shed uncoated threads Internal threads Class 2B 55Table 13 Fine thread series (UNF) Limits and tolerances for finished uncoated threads External threads Class 3A 56Table 14 Fine thread series (UNF) Limits and tolerances for finished uncoated threads Internal threads Class 3B 56Table 15 Coarse thread
18、 series (UNC) Basic dimensions 57Table 16 Fine thread series (UNF) Basic dimensions 58Table 17 Extra fine thread series (UNEF) Basic dimensions 59Table 18 4-thread series (4 UN) Basic dimensions 60Table 19 6-thread series (6 UN) Basic dimensions 61Table 20 8-thread series (8 UN) Basic dimensions 62T
19、able 21 12-thread series (12 UN) Basic dimensions 63Table 22 16-thread series (16 UN) Basic dimensions 64Table 23 20-thread series (20 UN) Basic dimensions 65Table 24 28-thread series (28 UN) Basic dimensions 66Table 25 32-thread series (32 UN) Basic dimensions 67Table 26 Thread data for unified thr
20、ead form 68Table 27 Diameter increments for UNS threads 69Table 28 Allowances for external threads of special diameter/pitch combinations (UNS threads) Classes 1A and 2A 72Table 29 Major diameter tolerances for external threads of special diameter/pitch combinations (UNS threads) 73Table 30 Effectiv
21、e and minor diameter tolerances for external threads of special diameter/pitch combinations (UNS threads) Class 1A 74 iiiBS 1580-1:2007Table 31 Effective and minor diameter tolerances for external threads of special diameter/pitch combinations (UNS threads) Class 2A 75Table 32 Effective and minor di
22、ameter tolerances for external threads of special diameter/pitch combinations (UNS threads) Class 3A 76Table 33 Effective diameter tolerances for internal threads of special diameter/pitch combinations (UNS threads) Class 1B 77Table 34 Effective diameter tolerances for internal threads of special di
23、ameter/pitch combinations (UNS threads) Class 2B 78Table 35 Effective diameter tolerances for internal threads of special diameter/pitch combinations (UNS threads) Class 3B 79Table 36 Minor diameter tolerances for internal threads of special diameter/pitch combinations (UNS threads) 80Table 37 Unifi
24、ed screw threads Decimal inch diameters with preferred pitches 81Table 38 Limits of size for UNS threads having decimal inch basic sizes and preferred pitches 82Table A.1 Limits of size of unified threads as given by screw thread tolerance formulae 93Table D.1 General symbols 103Summary of pagesThis
25、 document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 111 and a back cover. BSI 2009BS 1580-1:2007iv ForewordPublishing informationThis part of BS 1580 is published by BSI and came into effect on 31 December 2007. It was prepared by Subcommittee SFTSE/1, Screws and fast
26、eners technical specification committee, under the authority of Technical Committee FME/9, Nuts, bolts and accessories. A list of organizations represented on this committee can be obtained on request to its secretary.SupersessionThis part of BS 1580 supersedes BS 1580: Parts 1 a fine thread series
27、(UNF) from in to 1 in nominal diameter; an extra fine thread series (UNEF) from in to 1 in nominal diameter;b) standard constant pitch series: a 4-threads per inch series (4 UN) from 2 in to 6 in nominal diameter; a 6-threads per inch series (6 UN) from 1 in to 6 in nominal diameter; an 8-threads pe
28、r inch series (8 UN) from 1 in to 6 in nominal diameter; a 12-threads per inch series (12 UN) from in to 6 in nominal diameter; a 16-threads per inch series (16 UN) from in to 6 in nominal diameter; a 20-threads per inch series (20 UN) from in to 3 in nominal diameter; a 28-threads per inch series (
29、28 UN) from in to 1 in nominal diameter; a 32-threads per inch series (32 UN) from in to 1 in nominal diameter;c) a special thread series (UNS) with diameter/pitch combinations other than those specified for the standard series.NOTE 1 A transition fit series and an interference fit series of UNC and
30、 UNF threads for application to screwed studs are given in BS 2693-1 and -2, respectively.NOTE 2 Bases of tolerances and allowances are given in Annex A, guidance for calculating limits of size is given in Annex B, information on crest forms of external threads is given in Annex C, some general symb
31、ols are given in Annex D (see 3.2), information on tolerances is given in Annex E, guidance on selection and use of the standard unified thread series is given in Annex F and information and guidance on tolerance classes is given in Annex G.14-14-14-12-14-1116-58-716-116-58-716-516-516-12-716-BS 158
32、0-1:20072 2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.BS 6528:1984, Glos
33、sary of terms for cylindrical screw threadsBS 919-1:2007, Screw gauge limits and tolerances Part 1: Specification for gauges for screw threads of unified formBS 919-4, Screw gauge limits and tolerances Part 4: Limits of size for gauges for screw threads of unified form diameters in and larger3 Terms
34、 and definitions and symbols3.1 Terms and definitionsFor the purposes of this part of BS 1580 the terms and definitions given in BS 6528:1984 and the following apply.3.1.1 effective diameterdiameter of the pitch cylinderNOTE 1 This is the “simple” effective diameter, as distinct from the “virtual” e
35、ffective diameter (see 3.1.2).NOTE 2 Also known as pitch diameter.3.1.2 virtual effective diametereffective diameter of an imaginary thread of perfect pitch and flank angle, having the full depth of flanks, but clear at the crests and roots, which would just assemble with the actual thread over the
36、prescribed length of engagementNOTE The “virtual” effective diameter exceeds the simple effective diameter in the case of an external thread, but is less than the simple effective diameter in the case of an internal thread, by an amount corresponding to the combined diametral effects due to any erro
37、rs in the pitch and/or the flank angles of the thread.3.2 Symbols3.2.1 For the purposes of Figures 1 to 8 and Figure C.1a), b), c) and d) in this part of BS 1580 the following symbols apply.NOTE 1 These symbols, which relate to the thread profile, have been taken from BS ISO 68-2:1998 because the th
38、read profile specified in this part of BS 1580 is the same as that in BS ISO 68-2:1998. Also, these are the symbols given in BS 6528.D major diameter of internal thread D1minor diameter of internal threadD2effective diameter of internal thread (see Note 2)d major diameter of external threadd1minor d
39、iameter of external threadd2effective diameter of external thread (see Note 2)14- BSI 2009 3BS 1580-1:2007H height of fundamental triangleP pitchT toleranceTdtolerances for dTD1tolerances for D1TD2tolerances for D2Td1tolerances for d1Td2tolerances for d2NOTE 2 These are the symbols given for pitch d
40、iameter in BS 6528.3.2.2 For the purposes of the remaining figures, and the tables and annexes, in this part of BS 1580, the symbols given in Annex D apply.NOTE These symbols were given in the 1962 edition of this part of BS 1580 and have been retained for the convenience of users of the standard, i
41、n particular to enable the equations to be retained without alteration. The exception to this is the symbol for the pitch of the thread for which an upper case P is used throughout for consistency.4 Profile of unified screw threads4.1 Basic profileThe basic profile of unified screw threads shall be
42、as shown in Figure 1.NOTE This is the same as the profile of ISO inch screw threads specified in BS ISO 68-2.4.2 Design profilesThe design profile of internal threads, i.e. the form of internal threads in their maximum material condition, shall be as shown in Figure 2a). NOTE 1 This is the same as t
43、he basic profile except that, in practice, in order to avoid sharp corners at the root of the threads (at the major diameter), the roots may be rounded as shown by the dotted line and cleared beyond a width of P/8.The design profile of external threads in their maximum material condition shall be as
44、 shown in Figure 2b). It shall be the same as the basic form shown in Figure 1 except that the root of the thread (at the minor diameter) shall be rounded to a radius equal to 0.144 3P below the flat of width P/4. (See Notes 3 to 8.)The dimensions of the design profile of unified screw threads shall
45、 be as specified in Table 26. NOTE 2 The design forms of the external and internal threads, shown in Figure 2, are such that, if a pair of screw threads of the same basic size (each in its maximum material condition) is assembled, contact between the two threads will be confined to the flanks over t
46、he radial depth of (5/8)H as shown in Figure 1. The rounded root of the external thread will clear the flat of width P/4 at the minor diameter of the internal thread and the root of the internal thread will clear the flat of width P/8 at the major diameter of the external thread. BSI 2009BS 1580-1:2
47、0074 NOTE 3 To provide resistance to fatigue, it is important that the roots of the external threads should always be smoothly rounded within the limiting profiles specified. These limiting profiles permit manufacture by a new tool having a minimum crest radius of 0.108 3P, and its retention in serv
48、ice until its crest radius wears to 0.144 3P. (See Figure 2b and tolerance zone diagrams Figure 6, Figure 7 and Figure 8.) It is essential that the roots of external threads are never flat with sharp corners, as would result from the initial use of new screwing tools, rolls, or grinding wheels with flat crests.NOTE 4 The root of an internal thread in the maximum material condition is shown as a flat of width P/8 in Figure 2 and the minimum major diameter (basic size) specified in the tables is based on this theoretically
