BS-7496-2-1991.pdf

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1、BRITISH STANDARD BS 7496-2: 1991 Incorporating Amendment No. 1 Cross-recessed tapping screws Part 2: Specification for countersunk flat head screws Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:01:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7496-2:1991

2、 This British Standard, having been prepared under the direction of the General Mechanical Engineering Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 31 January 1992 BSI 08-1999 The following BSI references relate to the work on this sta

3、ndard: Committee reference GME/9 Draft for comment 90/82161 DC ISBN 0 580 20093 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the General Mechanical Engineering Standards Policy Committee (GME/-) to Technical Committee GME/9, upon which

4、the following bodies were represented: BEAMA Ltd. British Constructional Steelwork Association Ltd. British Industrial Fasteners Federation British Railways Board British Steel Industry British Steel Industry (Wire Section) Gauge and Tool Makers Association Ministry of Defence Society of Motor Manuf

5、acturers and Traders Limited Washer Manufacturers Association of Great Britain The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Furniture Manufacturers Federation British Independent Steel Producers Association National Association

6、 of Fastener Stockholders Amendments issued since publication Amd. No.DateComments 8502March 1995Indicated by a sideline in the margin Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:01:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7496-2:1991 BSI 08-1999i

7、 Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Dimensions1 3Characteristics3 4Designation3 Figure 1 Dimensions2 Table 1 Dimensions1 Table 2 Length l and tolerances2 Table 3 Characteristics3 Publications referred toInside back cover Licensed Copy: London South Bank Univer

8、sity, London South Bank University, Fri Dec 08 11:01:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7496-2:1991 ii BSI 08-1999 Foreword This Part of BS 7496 has been prepared under the direction of the General Mechanical Engineering Standards Policy Committee to provide part of a series of standar

9、ds on cross-recessed tapping screws. This Part of BS 7496 introduces the recess type “V” for countersunk flat head tapping screws. It effectively replaces the “Phillips” recess (type H in ISO 7050) on which the rest of the standard is based. In 1993 the European Committee for Standardization (CEN) a

10、ccepted ISO 7050:1983 as European Standard EN ISO 7050:1994. As a consequence of implementing the European Standard this Part of BS 7496 is amended to delete the requirements for countersunk flat head screws with recess type Z which are now specified in BS EN ISO 7050:1994. Attention is drawn to the

11、 fact that it is claimed that recess type “V” is the subject of British patent no. 1521 141, copies of which can be obtained from the Patent Office, 25 Southampton Buildings, London WC2A 1AY. BSI takes no position as to the validity of the patent or whether it is still in force. The patent will, fro

12、m the date of grant, be irrevocably endorsed “licences of right” under Section 46 of the Patents Act 1977, which states: “3) Where such an entry is made in respect of a patent a) any person shall, at any time after the entry is made, be entitled as of right to a licence under the patent on such term

13、s as may be settled by agreement or, in default of agreement, by the Comptroller on the application of the proprietor of the patent or the person requiring the licence.” Licence details may be obtained from the registered proprietor of the patent. A British Standard does not purport to include all t

14、he necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard 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

15、, pages 1 to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Fri

16、 Dec 08 11:01:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7496-2:1991 BSI 08-19991 1 Scope This Part of BS 7496 specifies requirements for the dimensions and characteristics of cross-recessed countersunk (flat) head tapping screws with thread sizes from ST 2.2 to ST 9.5 inclusive, recess type V

17、 and cone end types C and F. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Dimensions The dimensions and tolerances of cross-recessed countersunk flat head tapping screws and their recesses shall be as given in Table 1 and Table 2 and Figure 1

18、. Table 1 Dimensions Thread sizeST 2.2ST 2.9ST 3.5ST 4.2ST 4.8ST 5.5ST 6.3ST 8ST 9.5 Pa mmmmmmmmmmmmmmmmmm 0.81.11.31.41.61.81.82.12.1 abmax. 0.81.11.31.41.61.81.82.12.1 dktheoreticalc max. 4.46.38.29.410.411.512.617.320 actualmax. 3.85.57.38.49.310.311.315.818.3 min. 3.55.26.988.99.910.915.417.8 km

19、ax. 1.11.72.352.62.833.154.655.25 rmax. 0.81.21.41.622.22.43.24 Cross recess Recess no. 01234 Type Vm ref. 2.253.054.204.504.906.356.809.209.85 Penetration min. 1.111.381.501.752.102.232.744.064.72 max. 1.301.681.862.222.702.903.444.555.33 y ref.dCone end type C 22.63.23.74.3567.58 Cone end type F 1

20、.62.12.52.83.23.63.64.24.2 a P is the pitch of the thread. b Distance from the underside of the head to the first major diameter of the thread. c See BS EN 27721. d Length of incomplete thread. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:01:31 GMT+00:00 2

21、006, Uncontrolled Copy, (c) BSI BS 7496-2:1991 2 BSI 08-1999 Table 2 Length l and tolerances Cone end typeThread sizea C and FCF nom.min.max.min.max.ST 2.2ST 2.9ST 3.5ST 4.2ST 4.8ST 5.5ST 6.3ST 8ST 9.5 mmmmmmmmmm 4.53.75.33.74.5 6.55.77.35.76.5 9.58.710.38.79.5 1312.213.812.213 1615.216.815.216Range

22、 1918.219.818.219of 2221.222.820.722commercial 2524.225.823.725lengths 3230.733.330.732 3836.739.336.738 4543.746.343.545 5048.751.348.550 a Sizes marked with a dash are not usually manufactured. Figure 1 Dimensions Licensed Copy: London South Bank University, London South Bank University, Fri Dec 0

23、8 11:01:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7496-2:1991 BSI 08-19993 3 Characteristics The materials, mechanical properties, tolerances and recesses of cross-recessed countersunk flat head recessed tapping screws shall be as given in Table 3. Table 3 Characteristics 4 Designation When d

24、esignating for the purpose of an enquiry or order, the following information shall be given: a) general product description, i.e. countersunk flat head screws; b) the number of this British Standard, i.e. BS 7496-2; c) the letter M indicating that the product is ISO metric; d) the nominal size (thre

25、ad diameter) of the product in millimetres; e) the nominal length in millimetres; f) the cone end type, i.e. C or F; g) the type of recess, i.e. V; h) details of the coating (if requested) and the relevant British Standard. Example: The designation of a cross-recessed countersunk flat head tapping s

26、crew, with thread size d of ST 3.5, nominal length l of 16 mm, cone end type C and cross recess type V is as follows: Countersunk flat head screw BS 7496-2 M ST 3.5 16 C V CharacteristicRequirement MaterialSteel complying with BS EN ISO 2702 ThreadComplying with BS EN ISO 1478 Mechanical propertiesC

27、omplying with BS EN ISO 2702 Tolerances (for product grade A) Complying with BS 6322-1 Head gaugingComplying with BS EN 27721 Cross recessesComplying with BS 6605 FinishPlain AcceptabilityIn accordance with BS 6587 Protective coatingaAs requested in the enquiry or order and complying with the approp

28、riate British Standard, e.g. BS 1224, BS 1706, BS 7371 or BS 6338 a Alternative or additional protective coatings should be agreed between supplier and purchaser. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:01:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI

29、 4 blank Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:01:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7496-2:1991 BSI 08-1999 Publication(s) referred to BS 1224, Specification for electroplated coatings of nickel and chromium. BS 1706, Method for speci

30、fying electroplated coatings of zinc and cadmium on iron and steel. BS 6322, Tolerances for fasteners. BS 6322-1, Specification for tolerances of bolts, screws and nuts with thread diameters U 1.6 mm and k 150 mm and product grades A, B and C. BS 6338, Specification for chromate conversion coatings

31、on electroplated zinc and cadmium coatings. BS 6587, Method of acceptance inspection for fasteners. BS 6605, Specification for cross recesses for screws. BS 7371, Coatings on metal fasteners. BS EN ISO 1478, Tapping screw threads. BS EN ISO 2702, Heat-treated steel tapping screws Mechanical properti

32、es. BS EN 27721, Countersunk head screws Head configuration and gauging. ISO 7050, Cross recessed (flat) countersunk head tapping screws (common head style)1). 1) Referred to in the foreword only. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:01:31 GMT+00:0

33、0 2006, Uncontrolled Copy, (c) BSI BS 7496-2: 1991 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorpo

34、rated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone

35、 finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: 020 8996 9000. Fax: 020 8996 7400. BSI offers members an individual updating service called PLUS

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37、dards, it is BSI policy to supply the BSI implementation of those that have been published as British Standards, unless otherwise requested. Information on standards BSI provides a wide range of information on national, European and international standards through its Library and its Technical Help

38、to Exporters Service. Various BSI electronic information services are also available which give details on all its products and services. Contact the Information Centre. Tel: 020 8996 7111. Fax: 020 8996 7048. Subscribing members of BSI are kept up to date with standards developments and receive sub

39、stantial discounts on the purchase price of standards. For details of these and other benefits contact Membership Administration. Tel: 020 8996 7002. Fax: 020 8996 7001. Copyright Copyright subsists in all BSI publications. BSI also holds the copyright, in the UK, of the publications of the internat

40、ionalstandardization bodies. Except as permitted under the Copyright, Designs and Patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, photocopying, recording or otherwise without prior written permission from BSI. This do

41、es not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size, type or grade designations. If these details are to be used for any other purpose than implementation then the prior written permission of BSI must be obtained. If permission is granted, the terms may include royalty payments or a licensing agreement. Details and advice can be obtained from the Copyright Manager. Tel: 020 8996 7070. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:01:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI

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