1、BRITISH STANDARD BS 949-4:1990 EN 22857:1989 ISO 2857:1973 (incorporates amendment No. 1:1984 and amendment No. 2:1986) Screwing taps Part 4: Specification for metric ground thread taps: manufacturing tolerances This European Standard EN 22857 has the status of a British Standard UDC 621.993.1:621.8
2、8.082.1BS949-4:1990 This British Standard was published under the authority of the Board of BSI and comes intoeffect on 29 June 1990 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference MTE/4 Draft for comment 85/78210 DC ISBN 0 580 18629 6 Cooperating or
3、ganizations The European Committee for Standardization, under whose supervision this European Standard was prepared, comprises the national standards organizations of the following Western European countries. Austria Oesterreichisches Normungsinstitut Belgium Institut belge de normalisation Denmark
4、Dansk Standardiseringsraad Finland Suomen Standardisoimisliito, r.y. France Association franaise de normalisation Germany Deutsches Institut fr Normung e.V. Greece Hellenic Organization for Standardization Iceland Technological Institute of Iceland Ireland National Standards Authority of Ireland Ita
5、ly Ente Nazionale Italiano di Unificazione Luxemburg Inspection du Travail et des Mines Netherlands Nederlands Normalisatie-instituut Norway Norges Standardiseringsforbund Portugal Instituto Portugus de Qualidade Spain Asociacin Espaola de Normalizacin y Certificacin Sweden Standardiseringskommissio
6、nen i Sverige Switzerland Association suisse de normalisation United Kingdom British Standards Institution Amendments issued since publication Amd. No. Date of issue CommentsBS949-4:1990 BSI 10-1999 i Contents Page Cooperating organizations Inside front cover National foreword ii Brief history 2 Tex
7、t of EN 22857 3 1 Scope and field of application 3 2 References 3 3 Basic data 3 3.1 Thread profile of nuts 3 3.2 Thread profile of tap 4 3.3 Tolerance classes of taps 4 3.4 Calculation of tap thread dimensions of classes 1, 2 and 3 6 4 Manufacturing tolerances on tap threads 7 4.1 Major diameter d
8、7 4.2 Pitch diameter d 2 9 4.3 Minor diameter of tap d 1 11 4.4 Tolerances on the half-angle !/2 of thread 11 4.5 Cumulative pitch error T pover any number of threads 12 5 Designation and marking of taps 12 6 Example of calculation of the dimensions of the the threaded portion of a tap 13 Annex A Gr
9、ound thread taps for ISO metric threads of coarse pitch 14 Annex B Ground thread taps for ISO metric threads of fine pitch 17 National appendix A Inside back cover National appendix B Inside back cover Figure 1 3 Figure 2 4 Figure 3 4 Table 1 Minimum deviation Js in micrometres 8 Table 2 Values of d
10、eviations Em and Es in micrometres 9 Table 3 Tolerances on the half-angle !/2 11 Table 4 Tolerance on pitch 12BS949-4:1990 ii BSI 10-1999 National foreword This Part of BS949 has been prepared under the direction of the Machine, Engineers and Hand Tools Standards Policy Committee and supersedes the
11、clauses relating to ISO2857 of BS949-1:1976 (including amendment No.1) which is currently undergoing revision to take this and other requirements into account. It is identical with ISO2857:1973 including amendments No.1:1984 and No.2:1986 “Ground thread taps for ISO metric threads of tolerance4H to8
12、H and4G to6G coarse and fine pitches Manufacturing tolerances on the threaded portion” prepared by Technical Committee ISO/TC29 of the International Organization for Standardization (ISO) on which the United Kingdom was represented. In 1989 the European Committee for Standardization (CEN) accepted I
13、SO2587 and its amendments as the European Standard EN22857:1989. The publication of this Part of BS949 is to meet the obligations of the United Kingdom as a member of CEN to give EN22857:1989 the status of a national standard, without modification. The existing BS949-1:1976, BS949-2:1979 and BS949-3
14、:1982 are currently being revised to withdraw any conflicting requirements with EN22857 and EN25967:1989 (which is identical to BS949-5), again as a United Kingdom obligation as a member of CEN, and to update them taking account of ISO529:1975 including amendments No.1 and No.2, ISO2283:1972, ISO228
15、4:1987 and ISO5969:1979 which have not been adopted by CEN. It is envisaged that after the completion of these revisions BS949 will consist of the following Parts: Part 1: Specification of general dimensions; Part 2: Specification for unified thread taps: manufacturing tolerances; Part 3: Specificat
16、ion for pipe thread taps; Part 4: Specification for metric ground thread taps manufacturing tolerances; Part 5: Nomenclature and terminology 1) . NOTETextual error. It should be noted that on page22 of the original text of ISO2857:1973, the heading for the penultimate column should read “tolerance o
17、n a/2” not “tolerance on a and a/2 to conform with the modifications introduced by amendment No.1:1984. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Stand
18、ard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theENtitle page, pages2 to 22, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had ame
19、ndments incorporated. This will be indicated in the amendment table on the inside front cover. 1) Published.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 22857 September 1989 UDC 621.993.1:621.88.082.1 Key words: Power operated tools, taps, ISO metric threads, dimensional tolerances English v
20、ersion Ground thread taps for ISO metric threads of tolerances4H to8H and4G to6G coarse and fine pitches: Manufacturing tolerances on the threaded portion (ISO 2857:1973 incl. Amd1:1984 and Amd2:1986) Tarauds filets rectifis pour filetages mtriques ISO de tolrance 4H 8H et 4G 6G pas gros et pas fins
21、: Tolrances dexcution de la partie taille (ISO 2857:1973, Amd 1:1984 et Amd 2:1986 inclus) Geschliffene Gewindebohrer fr metrische ISO-Gewinde mit Toleranzfeld 4H bis 8H und 4G bis 6G fr Regel- und Feingewinde: Festigungstoleranzen des Gewindeteiles (ISO 2857:1973 mit Amd 1:1984 und Amd 2:1986) This
22、 European Standard was accepted by CEN on9 June1989 and is identical to the ISO standard as referred to. CEN members are bound to comply with the requirements of the CEN/CENELEC Common Rules which stipulate the conditions for giving this European Standard the status of a national standard without an
23、y alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language mad
24、e by translation under the responsibility of a CEN member into its own language and notified to CEN Central Secretariat has the same status as the official versions. CEN members are the national standards organizations of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland,
25、 Italy, Luxemburg, 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, B-1050 Brussels CEN 1989 Copyright reserved to all CEN me
26、mbers Ref. No. EN 22857:1989 EEN22857:1989 BSI 10-1999 2 Brief history Following consideration of the results of a Primary Questionnaire among members, the CEN Technical Board decided in March1988 to submit the International Standard ISO 2857:1973 including Amendment1:1984 and Amendment2:1986 Ground
27、 thread taps for ISO metric threads of tolerances4H to8H and4G to6G coarse and fine pitches; Manufacturing tolerances on the threaded portion to the Formal Vote. This vote was positive. Statement The text of the International Standard ISO2857:1973 including Amendment1:1984 and Amendment2:1986 having
28、 been approved by CEN as a European Standard without any modification according to the Common CEN/CENELEC Rules, the following countries are bound to implement this standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxemburg, Netherlands, Norway, Portuga
29、l, Spain, Sweden, Switzerland and United Kingdom.EN22857:1989 BSI 10-1999 3 1 Scope and field of application This International Standard specifies the manufacturing tolerances on the threaded portion of taps for producing the ISO metric threads of tolerance classes4H to8H and4G to6G as defined in IS
30、O/R965-I to III (excluding, consequently, classes7G and8G considered as usually produced with ground thread taps). It is valid for the short taps specified in ISO/R529 as well as for any other kind of ground thread taps with the same diameters and pitches. The internal threads produced with those ta
31、ps are conventionally designated by the simplified denomination of “nut” in agreement with the word used in ISO/R965 for the general designation of all internal threads. Annex A and Annex B give, for all threads with coarse and fine pitches, the manufacturing tolerances on the threaded position of t
32、aps for the following classes of nuts: 4H and 5H 6H 7H and 8H 2 References ISO/R 529, Short machine taps and hand taps. ISO/R 724, ISO general purpose metric screw threads Basic dimensions. ISO/R 965-I, ISO general purpose metric screw threads Tolerances Principles and basic data. ISO/R 965-II, ISO
33、general purpose metric screw threads Tolerances Limits of sizes for commercial bolt and nut threads Medium quality. ISO/R 965-III, ISO general purpose metric screw threads Tolerances Deviations for constructional threads. 3 Basic data 3.1 Thread profile of nuts: seeFigure 1. and 4G and 5G 6G Figure
34、1 EN22857:1989 4 BSI 10-1999 3.2 Thread profile of tap: seeFigure 2. 3.3 Tolerance classes of taps For the production of nut classes of the following classes: 4H 5H 6H 7H 8H with zero minimum clearance, 4G 5G 6G with positive minimum clearance, three tolerance classes have been accepted: Class 1 Cla
35、ss 2 Class 3 The tolerances of these three classes are determined as indicated hereafter, in terms of a tolerance unit t, the value of which is equal to the pitch tolerance value , grade5 of the nut (extrapolated up to pitch0,2mm): t = grade5 of the nut. Figure 2 Figure 3 T D 2 T D 2EN22857:1989 BSI
36、 10-1999 5 3.3.1 Tolerance on pitch diameter The value for the tap pitch diameter tolerance is the same for all three classes1,2 and3: it is equal to20% of t. The position of the tolerance of the tap with respect to the basic pitch diameter results from the lower deviation Em, the values of which ar
37、e (seeFigure 3): for tap class1: + 0,1 t for tap class2: + 0,3 t for tap class3: + 0,5 t 3.3.2 Choice of tolerance class of the tap with respect to the class of thread to be produced Unless otherwise specified, the taps of classes1 to3 will generally be used for the manufacture of nuts of the follow
38、ing classes: Class 1: for nuts of classes4H and5H Class 2: for nuts of classes6H and also4G and5G Class 3: for nuts of classes7H8H and also6G This correspondance has, however, only an indicative nature, since the accuracy of tapping can vary as a function of a series of factors such as: the material
39、 to be tapped, the condition of the machine tool, the tapping attachment, the tapping speed, the lubricant, etc. Users are therefore recommended to select in each case the most suitable class of tap for the manufacture of the required class of nut. T d 2EN22857:1989 6 BSI 10-1999 3.4 Calculation of
40、tap thread dimensions of classes1,2 and3 Class of tap Minimum tolerance on tap major diameter d = D of tap all d = D nominal diameter of tap Js = 0,4 t ad min. = D + Js Tolerance on tap pitch diameter d 2 1 Em = 0,1 t aEs = 0,3 t ad 2min. = d 2 b+ Em d 2max. = d 2 b+ Es 2 Em = 0,3 t aEs = 0,5 t ad 2
41、min. = d 2 b+ Em d 2max. = d 2 b+ Es 3 Em = 0,5 t aEs = 0,7 t ad 2min. = d 2 b+ Em d 2max. = d 2 b+ Es Tolerance on tap minor diameter all No tolerance is specified on this diameter. The thread root is generally, but not mandatorily, with a rounded form and the profile of the radius blending with th
42、e flanks of the thread should lie, in principle, under the line AB which corresponds with the internal diameter D 1of the basic ISO profile. a t = tolerance unit = pitch tolerance, grade5 of the nut. The values are given in ISO/R965-I, section9. b The d 2values correspond to the values of the pitch
43、diameter D 2of the nut in conformity with ISO/R724. T D 2EN22857:1989 BSI 10-1999 7 4 Manufacturing tolerances on tap threads 4.1 Major diameter d The minimum major diameter d min. shall be equal to the nominal diameter D of the nut, plus deviation Js. Deviation Js shall be greater than or equal to0
44、,4t. 2) The maximum major diameter d max. is not fixed and is left to the manufacturers judgement. 2) t =tolerance unit= , pitch tolerance, grade5 of the nut. (See ISO/R965-I. The values given for the pitch of0,2 have been obtained by extrapolation.) T D 2EN22857:1989 8 BSI 10-1999 Table 1 Minimum d
45、eviation Js in micrometres Nominal diameter Pitch Minimum deviation Js over up to and including 0,2 +20 0,99 1,4 0,25 +22 0,3 +24 0,2 +21 0,25 +24 1,4 2,8 0,35 +27 0,4 +28 0,45 +30 0,35 +28 0,5 +32 2,8 5,6 0,6 +36 0,7 +38 0,75 0,8 +40 0,75 +42 5,6 11,2 1 +47 1,25 +50 1,5 +56 1 +50 1,25 +56 11,2 22,4
46、 1,5 +60 1,75 +64 2 +68 2,5 +72 1 +53 1,5 +64 2 +72 22,4 45 3 +85 3,5 +90 4 +94 4,5 + 100 1,5 +68 2 +76 3 +90 45 90 4 + 100 5 + 106 5,5 + 112 6 + 120EN22857:1989 BSI 10-1999 9 4.2 Pitch diameter d 2 The maximum and minimum permissible values on the pitch diameters, d 2max. and d 2min., of the taps a
47、re calculated in terms of the deviations Em and Es given inTable 2. Table 2 Values of deviations Em and Es in micrometres Nominal diameter Pitch Deviations for pitch diameters Em and Es over up to and including classes 1 2 3 0,2 + 15 +5 0,99 1,4 0,25 + 17 +6 0,3 + 18 +6 + 30 + 18 0,2 + 16 +5 0,25 +
48、18 +6 1,4 2,8 0,35 + 20 +7 + 34 + 20 0,4 + 21 +7 + 36 + 21 0,45 + 23 +8 + 38 + 23 0,35 + 21 +7 + 36 + 21 0,5 + 24 +8 + 40 + 24 + 56 + 40 2,8 5,6 0,6 + 27 +9 + 45 + 27 + 63 + 45 0,7 + 29 + 10 + 48 + 29 + 67 + 48 0,75 0,8 + 30 + 10 + 50 + 30 + 70 + 50 0,75 + 32 + 11 + 53 + 32 + 74 + 53 1 + 35 + 12 + 5
49、9 + 35 + 83 + 59 5,6 11,2 1,25 + 38 + 13 + 63 + 38 + 88 + 63 1,5 + 42 + 14 + 70 + 42 + 98 + 70EN22857:1989 10 BSI 10-1999 Table 2 Values of deviations Em and Es in micrometres Nominal diameter Pitch Deviations for pitch diameters Em and Es over up to and including classes 1 2 3 1 + 38 + 13 +63 +38 +88 +63 1,25 + 42 + 14 +70 +42 +98 +70 11,2 22,4 1,5 + 45 + 15 +75 +45 + 105 +75 1,75 + 48 + 16 +80 +48 + 112 +80 2 + 51 + 17 +85 +51 + 119 +
