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1、BS 919-1:2007 Screw gauge limits and tolerances Part 1: Specification for gauges for screw threads of unified form ICS 21.040.30 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BRITISH STANDARD Licensed Copy: London South Bank University, London South Bank University, Fri Nov
2、16 07:27:17 GMT+00:00 2007, Uncontrolled Copy, (c) BSI Publishing and copyright information The BSI copyright notice displayed in this document indicates when the document was last issued. BSI 2007 ISBN 978 0 580 57933 2 The following BSI references relate to the work on this standard: Committee ref
3、erence TDW/4 Draft for comment 07/30158512 DC Publication history First published April 1952 Second edition, December 1960 Third edition, November 2007 Amendments issued since publication Amd. no.DateText affected BS 919-1:2007 Licensed Copy: London South Bank University, London South Bank Universit
4、y, Fri Nov 16 07:27:17 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BSI 2007i BS 919-1:2007 Contents Foreword iii 1Scope 1 2Normative references 1 3Terms and definitions and symbols 1 4Design 2 5Tolerances and thread forms 3 6Marking 25 Annexes Annex A (informative) Verifying conformity with BS 1580 2
5、6 Annex B (informative) Conventional illustration of tolerance zones 34 Annex C (informative) Effective diameter equivalent of pitch and angle errors 34 Annex D (informative) A system of gauging for screw threads before and after coating 37 Annex E (informative) Setting to size of adjustable screw r
6、ing gauges 40 Annex F (informative) Comparison between the designations of British and American gauges 42 Annex G (informative) Tolerances for major, effective and minor diameters and flank angle and pitch 43 Annex H (informative) Hardness 44 Bibliography 45 List of figures Figure 1 Disposition of e
7、ffective diameter tolerance zones for screw gauges 18 Figure 2 Thread forms of GO gauges 20 Figure 3 Thread forms of NOT GO gauges 21 Figure 4 Forms of thread for NOT GO effective diameter screw gauges 22 Figure 5 Thread forms of setting plugs 24 Figure B.1 Limits and tolerances for the effective di
8、ameters of internal and external threads 34 List of tables Table 1 Tolerances for GO screw plug gauges all classes 5 Table 2 Tolerances for NOT GO screw plug gauges all classes 6 Table 3 Tolerances for GO and NOT GO plain plug gauges for minor diameters 7 Table 4 Tolerances for GO screw ring gauges
9、solid type, all classes 7 Table 5 Tolerances for NOT GO effective diameter screw ring gauges solid type, all classes 8 Table 6 Tolerances for GO screw check plugs for GO screw ring gauges solid type 8 Table 7 Tolerances for NOT GO effective diameter check plugs for new GO screw ring gauges solid typ
10、e 9 Licensed Copy: London South Bank University, London South Bank University, Fri Nov 16 07:27:17 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS 919-1:2007 ii BSI 2007 Table 8 Tolerances for NOT GO effective diameter check plugs for worn GO ring screw gauges solid type 9 Table 9 Tolerances for GO sc
11、rew check plugs for NOT GO effective diameter ring gauges solid type 10 Table 10 Tolerances for NOT GO screw check plugs for NOT GO effective diameter ring gauges solid type 10 Table 11 Tolerances for GO and NOT GO plain check plugs for the minor diameters of GO and NOT GO screw ring gauges solid ty
12、pe 10 Table 12 Tolerances for adjustable GO screw ring and calliper gauges for all classes 11 Table 13 Tolerances for adjustable NOT GO screw ring and calliper gauges for all classes 12 Table 14 Tolerances for double length setting plugs for adjustable GO screw ring gauges 13 Table 15 Tolerances for
13、 double length setting plugs for adjustable NOT GO screw ring gauges 14 Table 16 Tolerances for single length setting plugs for adjustable GO screw calliper gauges 15 Table 17 Tolerances for single length setting plugs for adjustable NOT GO screw calliper gauges 15 Table 18 Tolerances for GO and NOT
14、 GO plain calliper (GAP) gauges for major diameters 16 Table 19 Constants for use in calculating gauge dimensions (inch) 17 Table C.1 Effective diameter equivalents of errors in pitch 35 Table C.2 Effective diameter equivalents of errors in flank angles 36 Table D.1 External threads with specified a
15、llowances which have to be maintained after coating Unified threads, Class 1A 38 Table D.2 External screw threads with specified allowances (in the uncoated condition) which can be absorbed by the coating Unified threads, Class 2A 38 Table D.3 External screw threads with no specified allowance Unifi
16、ed threads, Class 3A 39 Table D.4 Unified threads, Classes 1B and 2B 39 Table D.5 Unified threads, Class 3B 39 Table D.6 Summary of GO and NOT GO screw gauges and plain gauges for checking unified threads 40 Summary of pages This document comprises a front cover, an inside front cover, pages i to iv
17、, pages 1 to 45 and a back cover. Licensed Copy: London South Bank University, London South Bank University, Fri Nov 16 07:27:17 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BSI 2007iii BS 919-1:2007 Foreword Publishing information This British Standard is published by BSI and came into effect on 30 N
18、ovember 2007. It was prepared by Subcommittee SFTSE/1, Screws and fasteners technical specification committee, under the authority of Technical Committee TDW/4, Technical product realization. A list of organizations represented on these committees can be obtained on request to their secretaries. BS
19、919, Screw gauge limits and tolerances is in four parts: Part 1: Specification for gauges for screw threads of unified form Part 2: Specification for gauges for screw threads of Whitworth and B.A. forms Part 3: Specification for gauges for screw threads of ISO metric form Part 4: Limits of size for
20、gauges for screw threads of unified form diameters in and larger Supersession This Part of BS 919 supersedes BS 919-1:1960, which is withdrawn. Relationship with other publications This British Standard is intended for use with BS 1580, which specifies the corresponding screw threads. Information ab
21、out this document This British Standard has been fully revised to bring it up to date. Presentational conventions The provisions of this standard are presented in roman (i.e. upright) type. Its requirements are expressed in sentences in which the principal auxiliary verb is “shall”. Commentary, expl
22、anation and general informative material is presented in notes in smaller italic type, and does not constitute a normative element. Contractual and legal considerations This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct appl
23、ication. Compliance with a British Standard cannot confer immunity from legal obligations. 1 4 - Licensed Copy: London South Bank University, London South Bank University, Fri Nov 16 07:27:17 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iv BSI 2007This page deliberately left blank BS 919-1:2007 Licens
24、ed Copy: London South Bank University, London South Bank University, Fri Nov 16 07:27:17 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BSI 20071 BS 919-1:2007 1 Scope This part of BS 919 specifies requirements for the following types of gauges intended for use in the checking of products with unified s
25、crew threads for conformity with BS 1580. a)Screw gauges: 1)solid screw plug gauges, GO and NOT GO; 2)solid screw ring gauges, GO and NOT GO; 3)adjustable screw ring gauges, GO and NOT GO; 4)adjustable screw calliper gauges GO and NOT GO. b)Setting plugs for adjustable ring gauges and for calliper g
26、auges, GO and NOT GO: 1)double length; 2)single length. c)Screw check plugs for solid screw ring gauges, GO and NOT GO. d)Plug gauges and calliper gauges for the crest diameters of product threads, GO and NOT GO. Annex A gives information about the various types of gauges covered by BS 919. Annex B
27、explains the conventional method for showing the tolerance zones of gauges. Guidance on the calculation of the effective diameter equivalent of pitch and angle errors is given in Annex C. Annex D recommends a method for gauging screw threads before and after coating. Notes on the setting to size of
28、adjustable screw ring gauges are presented in Annex E, while Annex F presents a comparison of British and American screw thread terminology. Annex G discusses the tolerances for major, effective and minor diameters and flank angle and pitch permitted by BS 1580. Guidance on the hardness of gauges is
29、 given in Annex H. 2 Normative references The latest edition of the following referenced document (including any amendments) is indispensable for the application of this document. BS 1044-1, Specification for gauge blanks Part 1: Plug, ring and calliper gauges 3 Terms and definitions and symbols 3.1
30、Terms and definitions For the purposes of this part of BS 919, the terms and definitions given in BS 6528:1984 and the following apply. 3.1.1effective diameter diameter of the pitch cylinder NOTE 1 This is the “simple” effective diameter, as distinct from the “virtual” effective diameter (see 3.1.2)
31、. NOTE 2 Also known as “pitch diameter”. Licensed Copy: London South Bank University, London South Bank University, Fri Nov 16 07:27:17 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS 919-1:2007 2 BSI 2007 3.1.2virtual effective diameter effective diameter of an imaginary thread of perfect pitch and f
32、lank angle, having the full depth of flanks, but clear at the crests and roots, which would just assemble with the actual thread over the prescribed length of engagement NOTE The “virtual” effective diameter exceeds the effective diameter in the case of an external thread, but is less than the effec
33、tive diameter in the case of an internal thread, by an amount corresponding to the combined diametral effects due to any errors in the pitch and/or the flank angles of the thread. 3.2Symbols For the purposes of this part of BS 919, the following symbols apply. NOTE 1 These are repeated from BS 6528
34、for the convenience of users of this standard. Dmajor diameter of internal thread D1minor diameter of internal thread D2effective diameter of internal thread (see Note 2) dmajor diameter of external thread d1minor diameter of external thread d2effective diameter of external thread (see Note 2) Hheig
35、ht of fundamental triangle Ppitch NOTE 2 These are the symbols given for pitch diameter in BS 6528. 4 Design 4.1General The general dimensions of blanks suitable for both screw and plain gauges shall conform to BS 1044-1. 4.2Feather edges To avoid feather edges on screw plug and ring gauges and sett
36、ing plugs, the partial thread at both ends of the gauge shall be removed to a blunt start, except for: a)screw plug gauges and setting plugs in sizes below 0.150 in and/or with external cone centres; and b)screw ring gauges inch nominal size and smaller or with pitches of 20 threads per inch and fin
37、er, and all screw plug gauges and setting plugs with pitches of 28 threads per inch and finer for which a 60 chamfer from the axis of the gauge is permitted in lieu of the removal of the partial thread. Not more than one complete turn of the thread shall be removed to the point where the full thread
38、 form is obtained. On double length setting plugs with pitches of 28 threads per inch and coarser, where the truncated portion meets the full form portion, the feather edge shall be completely removed. 1 2 - - Licensed Copy: London South Bank University, London South Bank University, Fri Nov 16 07:2
39、7:17 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BSI 20073 BS 919-1:2007 4.3Dirt clearance grooves When specified by the user, screw plug gauges shall have a dirt clearance groove cut axial to the thread to a depth slightly below the root of the thread and at the position where the thread commences a
40、t its full section, as specified in 4.2. 4.4Removal of sharp edges All sharp edges on the gauging portions and handles shall be removed. 5 Tolerances and thread forms NOTE Since small inaccuracies in size and form of gauges are inevitable in their manufacture, tolerances are specified to control the
41、se inaccuracies to a degree which is both practical and economical. Attention has to be paid to the product tolerance and care taken that the gauge tolerance does not unduly absorb, or add to, the product tolerance, though it is not possible to lay down a hard and fast relationship between gauge tol
42、erance and product tolerance in the case of screw gauges. Absorption of product tolerance by the gauge tolerance depends upon the position of the gauge tolerance zone in relation to the product tolerance zone. Figure 1 illustrates the relative dispositions of gauge and product tolerance zones, using
43、 the conventional methods of showing tolerance zones explained in Annex B. 5.1Screw plug gauges The tolerance zones for GO and NOT GO screw gauges shall be as shown in Figure 1. Tolerances for GO screw plug gauges and for NOT GO effective diameter screw plug gauges shall be as specified in Table 1 a
44、nd Table 2, respectively. The form of thread for GO screw plug gauges shall be as shown in Figure 2a). NOTE Figure 3a) indicates the profile of a gauge which, theoretically, would verify that the thickness of the product thread is not less than half the basic pitch at a diameter equal to the minimum
45、 metal limit specified for the effective diameter of the product thread. Such a gauge would not only be difficult to measure but would also wear very quickly in use. The gauge is made practicable, however, by providing it with limited lengths of flank, as shown in Figure 3b). The longer these flanks
46、, the less critical does the gauge become in controlling the effective diameter of the product thread when the flank angles are in error or when other malformations exist. Alternative forms of thread for NOT GO effective diameter screw plug gauges are shown in Figure 4. Figure 4a) shows a short flan
47、k (or low addendum) gauge having an addendum of H/8, while Figure 4b) shows a long flank (or high addendum) gauge with an addendum of H/4. A long flank NOT GO effective diameter gauge is less effective than a short flank gauge in detecting thin threads when angle errors are present, or when other ma
48、lformations of the thread exist such as those due to tearing. Guidance on the selection of gauges is given in BS 1580. The American type high addendum NOT GO effective diameter screw plug gauge should be used for checking the numbered sizes of internal threads. Licensed Copy: London South Bank Unive
49、rsity, London South Bank University, Fri Nov 16 07:27:17 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS 919-1:2007 4 BSI 2007 5.2Plain plug gauges The disposition of the tolerance zones for plain plug gauges shall be as shown in Figure 1. Tolerances for GO and NOT GO plain plug gauges for minor diameters of internal threads shall be as specified in Table 3. 5.3Screw ring gauges and callipers The disposition of the toler