1、BRITISH STANDARD BS5317:1976 Specification for Metric length bars and their accessories UDC 621.753.3:531.717.5BS5317:1976 This British Standard, having been prepared under the directionof the Mechanical Engineering Industry StandardsCommittee, was published under the authorityofthe Executive Boardo
2、n 30April1976 BSI11-1999 First published, as part of BS1790 January1952 First revision, as part of BS1790January1961 First published, as BS5317April1976 The following BSI references relate to the work on this standard: Committee reference MEE/59 Draft for comment74/70741DC ISBN 0 580 09090 6 Co-oper
3、ating organizations The Mechanical Engineering Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Associated Offices Technical Committee Departmen
4、t of Trade Association of Consulting Engineers Electricity Supply Industry in England and Association of Hydraulic Equipment Wales Manufacturers Ltd. Engineering Equipment Users Association Association of Mining, Electrical and Federation of Manufacturers of Construction Mechanical Engineers Equipme
5、nt and Cranes British Compressed Air Society Institution of Gas Engineers British Electrical and Allied Manufacturers Institution of Heating and Ventilating Association Engineers British Gas Corporation Institution of Mechanical Engineers British Gear Manufacturers Association Institution of Plant E
6、ngineers British Internal Combustion Engine Institution of Production Engineers* Manufacturers Association London Transport Executive British Mechanical Engineering Confederation Machine Tool Trades Association British Pump Manufacturers Association Ministry of Defence* British Steel Corporation Nat
7、ional Coal Board British Steel Industry Process Plant Association Crown Agents for Oversea Governments and Railway Industry Association of Great Britain Administrations Royal Institute of British Architects Department of Employment (HM Factory Society of Motor Manufacturers and Inspectorate) Traders
8、 Ltd. Department of the Environment Telecommunication Engineering and Department of Industry Manufacturing Association Department of Industry National Engineering Laboratory The Government department and scientific and industrial organization marked with an asterisk in the above list, together with
9、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 Laboratory Department of Prices and Consumer Protection British Calibration Service Amendments issued since pub
10、lication Amd. No. Date of issue Comments 3052 June1979 Indicated by a sideline in the marginBS5317:1976 BSI 11-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii Section 1. General 1 Scope 1 2 References 1 3 Definitions 1 Section 2. Length bars 4 Description and use: gene
11、ral design 2 5 Material 4 6 Hardening and stabilizing 4 7 Finish 4 8 Accuracy 4 9 Connecting screws for grade1 and grade2 bars 6 10 Marking and essential particulars 6 11 Case 6 12 Protection against climatic conditions 6 Section 3. Accessories 13 Material 6 14 Method of attachment 6 15 Base 6 16 La
12、rge radiused jaw 7 17 Small plane-faced jaw 8 18 Spherical end piece 8 19 Screws 8 20 Case 9 21 Protection against climatic conditions 9 Appendix A Interchangeability with bars to BS1790:1961 10 Figure 1 Indication of Airy positions and axis 1 Figure 2 Exaggerated illustration of flatness tolerance
13、1 Figure 3 Exaggerated illustration of parallelism tolerance 2 Figure 4 Exaggerated illustration of squareness tolerance 2 Figure 5 Reference or calibration grade length bar 3 Figure 6 Grade1 or grade2 length bar 3 Figure 7 Threaded connection for length bars 4 Figure 8 Assembly of accessories 7 Fig
14、ure 9 Base 7 Figure 10 Large radiused jaw 7 Figure 11 Centrality of radius to thickness 8 Figure 12 Small plane-faced jaw 8 Figure 13 Spherical end piece 8 Table 1 Tolerances on reference grade length bars 5 Table 2 Tolerances on calibration grade length bars 5 Table 3 Tolerances on grade1 length ba
15、rs 5 Table 4 Tolerances on grade2 length bars 6 Publications referred to Inside back coverBS5317:1976 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 includ
16、ed with inch bars in BS1790. The latter was first published in1952 and revised in1961; 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 int
17、o combinations without any appreciable 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 pr
18、esent standard. Although four grades 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 “grade1” and “grade2”. Requirements for metric length bars and accessories have now been dele
19、ted from BS1790 and that standard 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 i
20、mmunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to10, 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
21、 amendment table on the inside front cover.BS5317:1976 BSI 11-1999 1 Section 1. General 1 Scope This British Standard relates to length bars (end standards) of the cylindrical type having flat, parallel end faces finished by lapping in metric sizes up to1200mm. NOTEIf longer bars are required they s
22、hould be uniform in diameter and straight overall to the limits laid down in8.1 and8.2; tolerances for flatness and parallelism of faces should be proportionate to those specified in the appropriate Table 1 to Table 4 and their lengths should comply with the requirements of8.4.2. Provision is made f
23、or 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 grades of accuracy, namely reference, calibration, grade1 and grade2. It gives general d
24、imensions, 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 to the essential features of design and accuracy of accessories for use with grade1 or grade
25、2 bars. Appendix A deals with interchangeability between these bars and bars made in accordance with BS1790. 2 References The titles of the British Standards referred to in this standard are listed on the inside back cover. 3 Definitions For the purposes of this British Standard the following defini
26、tions 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 (SeeFigure 1.) 3.2 axis of the bar the line passing through the centres of the cross sections at the Airy positions (SeeFigure 1.) 3.3 length this is defined, w
27、ith the bar mounted horizontally and referred to the standard reference temperature of20 C, as the distance from the centre of one of its faces to a flat surface in wringing contact with the opposite face, measured normal to the surface NOTE 1To realize this definition for the grade1 and2 types of b
28、ar 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 length, as defined above, is traceable to the primary standard of length, the length so determined
29、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 between two parallel planes which just envelop the measuring face 3.5 flatness tolerance the maximum p
30、ermissible deviation from flatness (SeeFigure 2.) Figure 1 Indication of Airy positionsandaxis Figure 2 Exaggerated illustration offlatnesstoleranceBS5317:1976 2 BSI 11-1999 3.6 deviation from parallelism the difference between the maximum and minimum lengths at any points on the measuring faces mea
31、sured perpendicular to the surface to which one face is wrung 3.7 parallelism tolerance the maximum permissible deviation from parallelism (SeeFigure 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
32、 under consideration (SeeFigure 3.) 3.9 squareness tolerance the maximum permissible deviation from squareness (SeeFigure 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
33、the highest order of accuracy as regards both the quality of their end faces and the finishing of their actual lengths to nominal size. They should be used only in “standards rooms” that are temperature controlled at20 C with comparators of suitably high sensitivity. They shall be measured by the Na
34、tional Physical Laboratory and supplied with a certificate of accuracy giving the deviations 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 u
35、sed only in “standards rooms” that are temperature controlled at20 C and with comparators 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 nom
36、inal lengths and confirming their full accordance with this standard. Certification 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 Grade1. These bars have internally threaded end
37、s and can thus be used in combination with each other. They are intended for use in inspection rooms and tool rooms. 4.1.4 Grade2. 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 Gene
38、ral design 4.2.1 Reference and calibration grades. These shall take the form of cylindrical bars22mm in diameter and shall have completely plane end faces. The Airy positions on all bars150mm in length and over shall be indicated by two symmetrically spaced pairs of bold circumferential lines scribe
39、d around the bars as shown in Figure 1 and Figure 5. The lines shall not stand proud of the surface of the bar. Figure 3 Exaggerated illustration ofparallelism tolerance Figure 4 Exaggerated illustration ofsquareness toleranceBS5317:1976 BSI 11-1999 3 4.2.2 Grade1 and grade2 bars (seeFigure 6). Grad
40、e1 and grade2 bars shall take the form of cylindrical bars22mm in diameter, internally threaded and recessed at both ends. The Airy positions on all bars150mm in length and over shall be as indicated for reference and calibration bars. The threaded connections at the ends of these bars shall be made
41、 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 supports at the calculated Airy positions for the
42、total length, i.e.supports equidistant from the ends separated by a distance equal to0.577 times the overall length of the combination, and the engraved lines on individual bars ignored. Under these conditions, adjustable supports are desirable. Figure 5 Reference or calibration grade length bars Fo
43、r enlarged view of threaded end, see Figure 7(a) Figure 6 Grade1 or grade2 length barBS5317:1976 4 BSI 11-1999 5 Material The bars shall be made of high quality tool steel free from non-metallic inclusions. 6 Hardening and stabilizing 6.1 Hardening. 25mm bars shall be hardened throughout their lengt
44、h. Bars over25mm up to and including125mm shall be hardened either throughout their length or at the ends only for a distance of not less than4mm. Longer bars shall be hardened at the ends only for a distance of about6mm and not less than4mm from each end. The hardness number of the end faces of the
45、 finished bars shall be not less than750HV 1) . 6.2 Stabilizing. The bars shall be stabilized after hardening and due attention shall be given to scale removal, particularly from any threaded holes. A recommended stabilizing treatment is to heat the bars to150 C and maintain them at this temperature
46、 for approximately10h followed by slow cooling. 7 Finish 7.1 The body of each bar shall be finished all over by fine grinding. The 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 blemishe
47、s 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 within154m for bars up to300mm
48、in length,254m for bars over300mm up to and including600mm in length, and within504m for bars longer than600mm. 8.2 Straightness. The body shall be straight within104m per100mm of length. Figure 7 Threaded connection for length bars 1) Diamond Pyramid Hardness Number. The approximate equivalent hard
49、ness number on the Rockwell C Scale is62HRC.BS5317:1976 BSI 11-1999 5 8.3 End faces 8.3.1 Flatness and parallelism. The tolerances on flatness and parallelism of the end faces shall be as given in Table 1 to Table 4. 8.3.2 Squareness, The end faces of all grades of bars shall be square with the axis of the bar to within1.24m over the diameter of the face for bars up to and including400mm in length and to within2.54m for bars over400mm in length. 8.4 Length 8.4.1 Tolerances. The tolerances on length shall be as
