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1、BRITISH STANDARD BS 5317:1976 Specification for Metric length bars and their accessories UDC 621.753.3:531.717.5 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:18:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5317:1976 This British Standard, having been prepared under the direction of
2、the Mechanical Engineering Industry Standards Committee, was published under the authority of the Executive Board on 30 April 1976 BSI 11-1999 First published, as part of BS 1790 January 1952 First revision, as part of BS 1790 January 1961 First published, as BS 5317 April 1976 The following BSI ref
3、erences relate to the work on this standard: Committee reference MEE/59 Draft for comment 74/70741DC ISBN 0 580 09090 6 Co-operating organizations The Mechanical Engineering Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the
4、 following Government departments and scientific and industrial organizations: Associated Offices Technical CommitteeDepartment of Trade Association of Consulting EngineersElectricity Supply Industry in England and Association of Hydraulic Equipment Wales Manufacturers Ltd.Engineering Equipment User
5、s Association Association of Mining, Electrical andFederation of Manufacturers of Construction Mechanical EngineersEquipment and Cranes British Compressed Air SocietyInstitution of Gas Engineers British Electrical and Allied ManufacturersInstitution of Heating and Ventilating AssociationEngineers Br
6、itish Gas CorporationInstitution of Mechanical Engineers British Gear Manufacturers AssociationInstitution of Plant Engineers British Internal Combustion EngineInstitution of Production Engineers* Manufacturers AssociationLondon Transport Executive British Mechanical Engineering ConfederationMachine
7、 Tool Trades Association British Pump Manufacturers AssociationMinistry of Defence* British Steel CorporationNational Coal Board British Steel IndustryProcess Plant Association Crown Agents for Oversea Governments and Railway Industry Association of Great Britain AdministrationsRoyal Institute of Br
8、itish Architects Department of Employment (HM Factory Society of Motor Manufacturers and Inspectorate)Traders Ltd. Department of the EnvironmentTelecommunication Engineering and Department of IndustryManufacturing Association Department of Industry National Engineering Laboratory The Government depa
9、rtment and scientific and industrial organization marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: Department of Industry National Physical Gauge and Toolmakers Association Labo
10、ratory Department of Prices and Consumer Protection British Calibration Service Amendments issued since publication Amd. No.Date of issueComments 3052June 1979Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:18:37 GMT+00:00 2006, Uncontrolled Copy, (c)
11、BSI BS 5317:1976 BSI 11-1999i Contents Page Co-operating organizationsInside front cover Forewordii Section 1. General 1Scope1 2References1 3Definitions1 Section 2. Length bars 4Description and use: general design2 5Material4 6Hardening and stabilizing4 7Finish4 8Accuracy4 9Connecting screws for gra
12、de 1 and grade 2 bars6 10Marking and essential particulars6 11Case6 12Protection against climatic conditions6 Section 3. Accessories 13Material6 14Method of attachment6 15Base6 16Large radiused jaw7 17Small plane-faced jaw8 18Spherical end piece8 19Screws8 20Case9 21Protection against climatic condi
13、tions9 Appendix A Interchangeability with bars to BS 1790:196110 Figure 1 Indication of Airy positions and axis1 Figure 2 Exaggerated illustration of flatness tolerance1 Figure 3 Exaggerated illustration of parallelism tolerance2 Figure 4 Exaggerated illustration of squareness tolerance2 Figure 5 Re
14、ference or calibration grade length bar3 Figure 6 Grade 1 or grade 2 length bar3 Figure 7 Threaded connection for length bars4 Figure 8 Assembly of accessories7 Figure 9 Base7 Figure 10 Large radiused jaw7 Figure 11 Centrality of radius to thickness8 Figure 12 Small plane-faced jaw8 Figure 13 Spheri
15、cal end piece8 Table 1 Tolerances on reference grade length bars5 Table 2 Tolerances on calibration grade length bars5 Table 3 Tolerances on grade 1 length bars5 Table 4 Tolerances on grade 2 length bars6 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 0
16、1 14:18:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5317:1976 ii BSI 11-1999 Foreword This British Standard, prepared under the authority of the Mechanical Engineering Industry Standards Committee, deals with metric length bars which have until now been included with inch bars in BS 1790. The l
17、atter was first published in 1952 and revised in 1961; among the features of the revision were the introduction of a calibration grade of bar and of a refined screw connection that had been developed by the National Physical Laboratory and enabled bars to be built into combinations without any appre
18、ciable loss of overall inherent accuracy. Although it was permissible to use the original type of connection with what were designated “workshop” grade bars, the “refined” type has been so generally adopted that it is the only one for which provision is made in the present standard. Although four gr
19、ades of length bars have been retained, it is considered that the descriptive terms “inspection” and “workshop” are misleading and they have been replaced by the designations “grade 1” and “grade 2”. Requirements for metric length bars and accessories have now been deleted from BS 1790 and that stan
20、dard should now be regarded as obsolescent. 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 Standard does not of itself confer immunity from legal obligation
21、s. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 10, 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 i
22、nside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:18:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5317:1976 BSI 11-19991 Section 1. General 1 Scope This British Standard relates to length bars (end standards) of the cylindrical type having flat, parallel end faces fini
23、shed by lapping in metric sizes up to 1 200 mm. NOTEIf longer bars are required they should be uniform in diameter and straight overall to the limits laid down in 8.1 and 8.2; tolerances for flatness and parallelism of faces should be proportionate to those specified in the appropriate Table 1 to Ta
24、ble 4 and their lengths should comply with the requirements of 8.4.2. Provision is made for two designs of length bar, one with complete plane faces and the other with annular faces surrounding an internally threaded hole at one end or both ends of the bar. Section 2 provides for length bars in four
25、 grades of accuracy, namely reference, calibration, grade 1 and grade 2. It gives general dimensions, tolerances on length and requirements for flatness, parallelism and squareness of faces for all grades of bars. Manufacturers supply single length bars or sets of selected sizes. Section 3 relates t
26、o the essential features of design and accuracy of accessories for use with grade 1 or grade 2 bars. Appendix A deals with interchangeability between these bars and bars made in accordance with BS 1790. 2 References The titles of the British Standards referred to in this standard are listed on the i
27、nside back cover. 3 Definitions For the purposes of this British Standard the following definitions apply. 3.1 airy positions those points at which a bar of uniform cross section has to be supported when used with its axis horizontal (See Figure 1.) 3.2 axis of the bar the line passing through the c
28、entres of the cross sections at the Airy positions (See Figure 1.) 3.3 length this is defined, with the bar mounted horizontally and referred to the standard reference temperature of 20 C, as the distance from the centre of one of its faces to a flat surface in wringing contact with the opposite fac
29、e, measured normal to the surface NOTE 1To realize this definition for the grade 1 and 2 types of bar it will be necessary to wring plane parallel end pieces of known thickness to one or both annular faces. NOTE 2It follows that when length measurements are made by comparison with a bar whose known
30、length, as defined above, is traceable to the primary standard of length, the length so determined always refers to the horizontal position of support regardless of whether the comparison is made with the bars supported vertically or horizontally. 3.4 deviation from flatness the minimum distance bet
31、ween two parallel planes which just envelop the measuring face 3.5 flatness tolerance the maximum permissible deviation from flatness (See Figure 2.) Figure 1 Indication of Airy positions and axis Figure 2 Exaggerated illustration of flatness tolerance Licensed Copy: sheffieldun sheffieldun, na, Fri
32、 Dec 01 14:18:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5317:1976 2 BSI 11-1999 3.6 deviation from parallelism the difference between the maximum and minimum lengths at any points on the measuring faces measured perpendicular to the surface to which one face is wrung 3.7 parallelism tolerance
33、 the maximum permissible deviation from parallelism (See Figure 3.) 3.8 deviation from squareness the minimum distance between two parallel planes normal to the axis of the bar which just envelop the measuring face under consideration (See Figure 3.) 3.9 squareness tolerance the maximum permissible
34、deviation from squareness (See Figure 4.) Section 2. Length bars 4 Description and use: general design 4.1 Description and use 4.1.1 Reference grade. These bars are intended for use as reference standards and embody the highest order of accuracy as regards both the quality of their end faces and the
35、 finishing of their actual lengths to nominal size. They should be used only in “standards rooms” that are temperature controlled at 20 C with comparators of suitably high sensitivity. They shall be measured by the National Physical Laboratory and supplied with a certificate of accuracy giving the d
36、eviations from their nominal lengths and confirming their full accordance with this standard. 4.1.2 Calibration grade. These bars are intended for use in the calibration of length measuring standards. They should be used only in “standards rooms” that are temperature controlled at 20 C and with comp
37、arators of suitably high sensitivity. They shall be measured either by interferometric methods or by comparison with calibrated standards and supplied with a certificate of accuracy giving the deviations from their nominal lengths and confirming their full accordance with this standard. Certificatio
38、n of these bars may be carried out by the National Physical Laboratory or by a Laboratory approved by the British Calibration Service for this class of measurement. 4.1.3 Grade 1. These bars have internally threaded ends and can thus be used in combination with each other. They are intended for use
39、in inspection rooms and tool rooms. 4.1.4 Grade 2. These bars also have internally threaded ends and can be used with gauge blocks, comparators or various accessories for measuring gauges, jigs, workpieces, etc. 4.2 General design 4.2.1 Reference and calibration grades. These shall take the form of
40、cylindrical bars 22 mm in diameter and shall have completely plane end faces. The Airy positions on all bars 150 mm in length and over shall be indicated by two symmetrically spaced pairs of bold circumferential lines scribed around the bars as shown in Figure 1 and Figure 5. The lines shall not sta
41、nd proud of the surface of the bar. Figure 3 Exaggerated illustration of parallelism tolerance Figure 4 Exaggerated illustration of squareness tolerance Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:18:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5317:1976 BSI 11-19993 4.2.2 Grade 1
42、and grade 2 bars (see Figure 6). Grade 1 and grade 2 bars shall take the form of cylindrical bars 22 mm in diameter, internally threaded and recessed at both ends. The Airy positions on all bars 150 mm in length and over shall be as indicated for reference and calibration bars. The threaded connecti
43、ons at the ends of these bars shall be made in accordance with the dimensions and tolerances specified in Figure 7. All threaded connections shall be assembled hand tight only. NOTEBars screwed together in combination and intended for use in the horizontal position should be supported on two support
44、s at the calculated Airy positions for the total length, i.e. supports equidistant from the ends separated by a distance equal to 0.577 times the overall length of the combination, and the engraved lines on individual bars ignored. Under these conditions, adjustable supports are desirable. Figure 5
45、Reference or calibration grade length bars For enlarged view of threaded end, see Figure 7(a) Figure 6 Grade 1 or grade 2 length bar Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:18:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5317:1976 4 BSI 11-1999 5 Material The bars shall be made
46、 of high quality tool steel free from non-metallic inclusions. 6 Hardening and stabilizing 6.1 Hardening. 25 mm bars shall be hardened throughout their length. Bars over 25 mm up to and including 125 mm shall be hardened either throughout their length or at the ends only for a distance of not less t
47、han 4 mm. Longer bars shall be hardened at the ends only for a distance of about 6 mm and not less than 4 mm from each end. The hardness number of the end faces of the finished bars shall be not less than 750 HV1). 6.2 Stabilizing. The bars shall be stabilized after hardening and due attention shall
48、 be given to scale removal, particularly from any threaded holes. A recommended stabilizing treatment is to heat the bars to 150 C and maintain them at this temperature for approximately 10 h followed by slow cooling. 7 Finish 7.1 The body of each bar shall be finished all over by fine grinding. The
49、 end faces of the bars shall be lapped to provide a finish of the highest quality both for appearance and wringing quality. They shall be free from scratches and blemishes of any noticeable character. The edges of all bars shall be radiused as shown in Figure 7(a). Threaded holes and screws, when provided, shall be cleanly finished and all sharp edges shall be removed. 8 Accuracy 8.1 Diameter. The diameter of each bar shall be uniform within 15 4m for bars up to 300 mm in length, 25 4m for bars over 300 mm up to an
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