1、BSI Standards PublicationSpecification for internal micrometers (including stick micrometers)BS 959:2008Incorporating Corrigendum No. 1BS 959:2008 BRITISH STANDARDPublishing and copyright informationThe BSI copyright notice displayed in this document indicates when the document was last issued. The
2、British Standards Institution 2014 Published by BSI Standards Limited 2014ISBN 978 0 580 84673 1ICS 17.040.30The following BSI references relate to the work on this standard: Committee reference TDW/4 Draft for comment 08/30177716 DCPublication historyFirst published July 1941 Second edition January
3、 1951 Third edition November 2008Amendments issued since publicationAmd. No. Date Text affected C1 October 2014 Clause 19 and Table 4 correctedBRITISH STANDARD The British Standards Institution 2014 iBS 959:2008ContentsForeword ii1 Scope 12 Normative references 2Section 1: Internal micrometers 33 Ma
4、terial of measuring head 34 Measuring face of measuring head 35 Micrometer screw 36 Thimble and barrel 37 Extension rods 58 Spacing collars 59 Adjustment 510 Accuracy 611 Rigidity 612 Handle 713 Marking 714 Case 715 Packing 7Section 2: Stick micrometers 816 Terminal and abutment faces 817 Screwed jo
5、ints 818 Extension rods 919 Accuracy of micrometer unit 920 Accuracy of extension rods 921 Rigidity 922 Marking 1023 Gap setting gauges 1024 Case 1025 Packing 10AnnexAnnex A (normative) Method of test for accuracy of internal micrometer readings 11Bibliography 13List of figuresFigure 1 Measurement o
6、f distance from barrel to reading end of graduation 4Figure 2 Application of load in testing for rigidity 7Figure 3 Stick micrometer components 8Figure 4 Gap setting gauge 10List of tablesTable 1 Measuring heads metric measurements 1Table 2 Measuring heads inch measurements 1Table 3 Maximum permissi
7、ble errors 6Table 4 Tolerances for extension rods 9Table A.1 Measuring head readings 12Summary of pagesThis document comprises a front cover, an inside front cover, pages i to ii, pages 1 to 14, an inside back cover and a back cover.BS 959:2008ii The British Standards Institution 2014BRITISH STANDAR
8、DForewordPublishing informationThis British Standard is published by BSI and came into effect on 30 November 2008. It was prepared by Technical Committee TDW/4, Technical product realization. A list of organizations represented on this committee can be obtained on request to its secretary.Supersessi
9、onThis British Standard supersedes BS 959:1950, which is withdrawn.Information about this documentThis British Standard has been fully revised to bring it up to date. Text introduced by or altered by Corrigendum No. 1 is indicated in the text by tags . Minor editorial corrections are not tagged.Pres
10、entational conventionsThe 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, explanation and general informative material is presented in smaller italic type, and does not co
11、nstitute a normative element.Contractual and legal considerationsThis publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.BRITISH STANDAR
12、D The British Standards Institution 2014 1BS 959:20081 ScopeThis standard specifies requirements for internal micrometers comprising a measuring head, extension rods with or without spacing collars, and, in the smaller sizes, a handle.Provision is made for three sizes of measuring heads, in both met
13、ric and inch units, as shown in Table 1 and Table 2.NOTE Attention is drawn to the fact that metric dimensions are not necessarily direct conversions of the imperial dimensions.Table 1 Measuring heads metric measurementsSize of head Length of graduated scale on barrel mmUsual ranges of the instrumen
14、t when used with extension rodsmmSize 1 5 or 6.5 2550Size 2 10 or 13 501505020050300Size 3 25 200+Table 2 Measuring heads inch measurementsSize of head Length of graduated scale on barrel inUsual ranges of the instrument when used with extension rodsinSize 114 12Size 2 12or 1 26 28 212 Size 3 1 8+Th
15、is standard also covers stick micrometers, which are designed for the measurement of longer internal lengths, and comprise the following parts:a) a 150 mm or 300 mm or 6 in or 12 in micrometer unit, fitted with a micrometer of 25 mm or 1 in range, and having rounded terminal faces;b) a series of ext
16、ension rods which, together with the micrometer unit, permit a continuous range of measurement up to the maximum length required.Annex A gives a method of test for the accuracy of internal micrometer readings.BS 959:20082 The British Standards Institution 2014BRITISH STANDARD2 Normative referencesTh
17、e following referenced document is indispensable for the application of this document. The latest edition of the referenced document (including any amendments) applies.BS 84, Parallel screw threads of Whitworth form Requirements BRITISH STANDARD The British Standards Institution 2014 3BS 959:2008Sec
18、tion 1: Internal micrometers3 Material of measuring headThe body of the measuring head shall be of a suitable quality of steel. Its spindle and terminal measuring face shall be of high grade tool steel. This measuring face of the anvil shall be hardened to give a diamond pyramid hardness number of n
19、ot less than 800 (62 on the Rockwell C scale). NOTE It is recommended that the measuring face be tipped with tungsten carbide or other suitable hard material, or be faced with a deposit of hard chromium.4 Measuring face of measuring headThe radius of curvature of the measuring face shall be slightly
20、 less than half of the smallest measuring range of the micrometer.5 Micrometer screw5.1 The micrometer screw shall have a pitch of 0.5 mm or 140 in.NOTE The threads of the screw and nut should be truncated so as to confine contact to the flanks of the thread.5.2 The screw shall be lubricated with a
21、thin, light, noncorrosive oil, and shall run smoothly throughout the length of its travel. 5.3 It shall be possible, either by means of the adjusting nut or by other means, to arrange for the thimble to be sufficiently tight for the micrometer to retain its reading after being set. 5.4 There shall b
22、e no perceptible backlash between the spindle screw and nut.5.5 When the micrometer is at its maximum reading there shall be full engagement of the nut and micrometer screw.NOTE The travel of the micrometer should be continued for at least one turn of the screw beyond each end of the graduated scale
23、 on the barrel.5.6 A means shall be provided (e.g. a spanner or key) for compensating for wear between the screw and nut. 6 Thimble and barrel6.1 The diameter of the graduated edge of the thimble (Figure 1, dimension A) shall be no less than 10.32 mm or 1332 in. 6.2 The angle of the bevel (Figure 1,
24、 angle ) shall be no more than 20.NOTE It is recommended that, for ease of reading, the angle of the bevel should be 15.6.3 The distance from the barrel to the reading end of the graduation on the thimble (Figure 1, dimension B) shall not exceed 0.381 mm or 0.015 in.BS 959:20084 The British Standard
25、s Institution 2014BRITISH STANDARDFigure 1 Measurement of distance from barrel to reading end of graduation2AB1Key1 Thimble2 Barrel6.4 All graduation lines shall be clearly cut. Those on the thimble and the fiducial line on the barrel shall have a width of 0.15 mm to 0.20 mm or 0.006 in to 0.008 in.
26、 NOTE 1 Whilst the thickness of the remaining graduations on the barrel is not of prime importance, it is recommended that these graduations do not vary in thickness from the others by an obvious amount.NOTE 2 It is recommended that, for ease of reading, the surfaces of the thimble and barrel should
27、 have a dull finish and that the graduation lines should be blackened.6.5 The thimble and barrel shall be graduated as follows.a) For metric reading micrometers, the thimble shall be graduated with 50 divisions, each representing 0.01 mm and numbered at 0, 5, 10, 15 etc., up to 45.The barrel shall b
28、ear a longitudinal fiducial line which is parallel to the axis of the spindle and graduated in 0.5 mm intervals. The first, and every tenth, graduation shall be numbered 0, 5, 10, 15, 20 and 25 respectively. The graduation lines indicating full millimetres shall be distinguished from the graduation
29、lines indicating half millimetres either by length or position.b) For inch reading micrometers, the thimble shall be graduated with 25 divisions, each representing 0.001 in and numbered at 0, 5, 10, 15, and 20.The barrel shall bear a longitudinal fiducial line which shall be graduated in 140 in inte
30、rvals and be parallel to the axis of the spindle. Every 110 in graduation shall be numbered, and every 110 in and 120 in graduation shall be slightly extended either above or below the fiducial line.BRITISH STANDARD The British Standards Institution 2014 5BS 959:20087 Extension rods7.1 Suitable exte
31、nsion rods shall be included to enable any measurement to be made throughout the range specified for the set, spacing collars being used where necessary. NOTE Each rod can incorporate its own measuring anvil; alternatively, the rods can take the form of distance pieces to which a separate common anv
32、il piece may be fitted.7.2 The method of assembling the extension rods with the measuring head shall be simple, positive and accurate. NOTE 1 In order to facilitate the assembling of the instrument for any desired range of measurement, each rod should be marked with the range of measurement for whic
33、h it is applicable.NOTE 2 In each joint of the assembly, one of the abutting faces should be provided with dirt clearance grooves.7.3 The rods shall be made of good quality steel.7.4 Each measuring face shall be hardened to give a diamond pyramid hardness number of not less than 800 (62 on the Rockw
34、ell C scale). NOTE It is desirable that each measuring face be tipped with tungsten carbide or other hard alloy, or be faced with a deposit of hard chromium.7.5 The radius of curvature of all measuring faces shall be slightly less than half of the smallest measuring range of the micrometer.7.6 Each
35、measuring face and each contact face shall be finished by lapping.7.7 All sharp edges shall be removed.NOTE The extension rods should be fitted with conveniently placed finger grips of heatinsulating material.8 Spacing collarsThe spacing collars shall be made of good quality steel. The ends shall be
36、 finished, preferably by lapping, in such a way that the end faces are flat and square to the axis. All sharp edges shall be removed.At least one face of each spacing collar shall be provided with dirt clearance grooves.9 AdjustmentEach micrometer shall be provided with a means for adjusting the zer
37、o setting (e.g. a spanner or key), such that, after resetting, the parts are secured and the original accuracy of the instrument is not impaired. In micrometer sets in which each extension rod has its own measuring face, a suitable adjustment for zero setting shall be incorporated in each extension
38、rod; for example, the attachment of the anvil by means of a frictiontight fine pitch thread. NOTE In such types there should be no adjustment on the micrometer head. In micrometer sets in which the extension rods take the form of distance pieces to any one of which is added a separate common anvil p
39、iece, the adjustment for zero setting may be incorporated either in the anvil piece or in the measuring head.BS 959:20086 The British Standards Institution 2014BRITISH STANDARD10 AccuracyAt an ambient temperature of 20 C, each measuring head with its associated extension rods (and collars if used) s
40、hall conform to the limits of error specified in Table 3, when the thimble reading is zero.Table 3 Maximum permissible errorsMeasuring range Maximum permissible error in lengthmm25G150151G300301G450451G600601G900mm 0.005 0.010 0.015 0.020 0.025in1G67G1213G1819G2425G36in 0.000 2 0.000 4 0.000 6 0.000
41、 8 0.001 0The measuring head shall not show a range of error in the traverse of the micrometer screw greater than 0.003 mm or 0.000 1 in.NOTE The range of error in the calibration of the micrometer screw is independent of the zero setting; it represents the maximum difference between the ordinates o
42、f the curve of error in the readings obtained on calibrating the screw at a number of positions along its traverse. These positions check not only the progressive errors in the screw but also the accuracy of the graduations round the thimble and on the fiducial line.11 Rigidity11.1 When tested in ac
43、cordance with 11.2, the deflection of the midpoint under the applied load shall not exceed 0.051 mm or 0.002 in for an assembly measuring 150 mm or 6 in in length. With each increase in length of 25 mm or 1 in, the deflection shall be no more than 0.051 mm or 0.002 in, up to a maximum deflection of
44、1.27 mm or 0.050 in for an assembly measuring 760 mm or 30 in.11.2 Assemble the micrometer using any combination of extension rods and spacing collars. Support the assembled unit at its ends, as shown in Figure 2, and apply a load of 0.5 kg or 1 lb. BRITISH STANDARD The British Standards Institution
45、 2014 7BS 959:2008Figure 2 Application of load in testing for rigidity1Key1 0.5 kg or 1 lb mass12 HandleEach micrometer set for the measuring range 25 mm to 50 mm or 1 in to 2 in shall be supplied with a suitable detachable handle. NOTE In micrometer sets for larger ranges of measurements a handle i
46、s optional.13 MarkingEach measuring head and component in a set shall have a common serial number legibly and permanently marked upon it, in characters not less than 0.63 mm or 0.025 in high. The measuring head shall be similarly marked with the manufacturers name or trade mark.14 CaseEach micromete
47、r set shall be supplied in a suitable protective case or box in which there is a separate compartment for each component. The case or box shall be so designed that when it is closed the components cannot become displaced.15 PackingEach measuring head shall be coated with a suitable thin, noncorrosiv
48、e, light oil and shall be securely wrapped. Each extension bar, collar and handle shall be coated with an anticorrosive preparation (e.g. harddrying lanolin).BS 959:20088 The British Standards Institution 2014BRITISH STANDARDSection 2: Stick micrometersNOTE The components of a stick micrometer are i
49、llustrated in Figure 3.Figure 3 Stick micrometer components12 2 24 23 3662578Key1 Terminal face2 Fixed insulating sleeve3 Screwed joint 38 in 26.t.p.i. Whit4 Loose insulating sleeve5 Micrometer unit6 Abutment face7 Extension rod8 End piece16 Terminal and abutment facesThe radius of curvature of the terminal faces of the micrometer unit shall be slightly less than half of the smallest measuring range of the micrometer unit.The terminal faces shall be hardened to a diamond pyramid hardness
