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1、Precision vernier callipers Requirements and test methods BS 887:2008 raising standards worldwide NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BSI British Standards Licensed Copy: London South Bank University, South Bank University, 31/01/2009 03:44, Uncontrolled Copy, (c)
2、BSI BS 887:2008BritiSh Standard Publishing and copyright information the BSi copyright notice displayed in this document indicates when the document was last issued. BSi 2008 iSBn 978 0 580 62031 7 iCS 17.040.30 the following BSi references relate to the work on this standard: Committee reference td
3、W/4 draft for comment 08/30177877 dC Publication history First published February 1940 First revision May 1950 Second revision July 1982 third (present) revision November 2008 Amendments issued since publication Amd. No. Date Text affected Licensed Copy: London South Bank University, South Bank Univ
4、ersity, 31/01/2009 03:44, Uncontrolled Copy, (c) BSI BritiSh Standard BSI 2008 i BS 887:2008 Summary of pages this document comprises a front cover, an inside front cover, pages i to ii, pages 1 to 16, an inside back cover and a back cover. Contents Foreword ii 1 Scope 1 2 normative references 1 3 t
5、erms and definitions 1 4 Construction 2 5 Scales 5 6 accuracy of reading 10 7 Protection 10 Annexes annex a (informative) recommended minimum crosssection of beam 11 annex B (normative) Methods of test 12 annex C (informative) Use of a precision vernier calliper 14 Bibliography 15 List of figures Fi
6、gure 1 illustration of the components of a precision vernier caliper, and their nomenclature 3 Figure 2 distance of vernier main scale 7 Figure 3 Enlarged view of vernier scale with main scale engraved in millimeters 9 Figure 4 Enlarged view of vernier scale with main scale engraved in centimetres 9
7、 Figure 5 Enlarged view of vernier scale with main scale engraved in inches 9 List of tables table 1 Measuring ranges 2 table 2 Projection of jaws from guiding surface of beam, J 4 table 3 Faces for internal measurements 5 table 4 Layout of scales 8 table 5 deviation of reading 10 table a.1a Minimum
8、 beam crosssections Metric callipers 11 table a.1B Minimum beam crosssections imperial callipers 11 Licensed Copy: London South Bank University, South Bank University, 31/01/2009 03:44, Uncontrolled Copy, (c) BSI BS 887:2008 ii BSI 2008 BritiSh Standard Foreword Publishing information this British S
9、tandard 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. Supersession this British Standard supersedes BS 887:1
10、982, which is withdrawn. Information about this document this standard has been revised to bring it up to date. readers are informed of the drafting of iSO diS 133851 Geometrical product specifications (GPS) dimensional measuring equipments Part 1: Callipers; design and metrological requirements, cu
11、rrently being carried out by iSO/tC 213, due to be adopted by CEn as an En iSO. Because industry still has a need for imperial callipers, this revision specifies requirements for both metric reading and imperial reading instruments. it includes requirements for a single design of vernier scale which
12、 can have graduations either in metric or in imperial units. 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, explanation and general inform
13、ative material is presented 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 application. Compliance with a British
14、Standard cannot confer immunity from legal obligations. Licensed Copy: London South Bank University, South Bank University, 31/01/2009 03:44, Uncontrolled Copy, (c) BSI BritiSh Standard BSI 2008 1 BS 887:2008 1 Scope this British Standard specifies requirements for the construction, for the accuracy
15、 at the reference temperature of 20 C and for the protection of metric and imperial precision vernier callipers with external and internal contact faces. the standard specifies requirements for metric callipers to measure lengths up to a maximum of 1 000 mm using a main scale and a vernier scale gra
16、duated to read to 0.02 mm and for imperial callipers to measure lengths up to a maximum of 48 in using a main scale and vernier scale graduated to read to 0.001 in. this standard does not specify full requirements for callipers with an electronic display, although the requirements for the beam, slid
17、er and measurement faces may be the same as the vernier calliper. 2 Normative references the following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced docum
18、ent (including any amendments) applies. BS 817, Surface plates Requirements BS 113319, Packaging code Section 19: Use of desiccants in packaging BS 2795, Specification for dial test indicators (lever type) for linear measurement BS En iSO 463, Geometrical Product Specifications (GPS) Dimensional mea
19、suring equipment Design and metrological characteristics of mechanical dial gauges 3 Terms and definitions For the purposes of this British Standard, the following terms and definitions apply. 3.1 deviation of reading difference between the vernier scale reading and the length separating the externa
20、l measurement faces 3.2 measuring range range of lengths that can be measured using the external measurement faces without the vernier scale extending beyond the main scale NOTE 1 Attention is drawn to the fact that the metric dimensions are not necessarily direct conversions of the imperial dimensi
21、ons. For instance, the vernier division of 0.02 mm marked on the metric calliper corresponds to a 0.001 in vernier division on the imperial calliper, whereas the actual conversion is 0.001 in = 0.0254 mm. NOTE 2 Recommended minimum beam cross-sections are given in Annex A, methods of test are given
22、in Annex B and guidance on the use of a precision vernier caliper is given in Annex C. NOTE The components of a precision vernier caliper are illustrated in Figure 1, which also gives the nomenclature. Licensed Copy: London South Bank University, South Bank University, 31/01/2009 03:44, Uncontrolled
23、 Copy, (c) BSI BS 887:2008 2 BSI 2008 BritiSh Standard 4 Construction 4.1 Material the slider and beam shall be of carbon steel or stainless steel. the coefficient of thermal expansion of the steel, in the temperature range 10 C to 30 C shall be (11.5 1.0) 106/C. the measurement faces shall be harde
24、ned to not less than 700 hV for carbon steel and not less than 550 hV for stainless steel. Finished callipers shall be free from internal stresses. 4.2 Measuring ranges the measuring ranges shall be as specified in table 1. table 1 Measuring ranges Metric mm Imperial in 0 to 150 0 to 6 0 to 300 0 to
25、 12 0 to 600 0 to 18 0 to 1 000 0 to 24 0 to 36 0 to 48 4.3 Beam the beam shall be long enough to prevent the sliding jaw assembly from protruding beyond the end of the beam when the assembly is at the upper limit of the measuring range. 4.4 Jaws 4.4.1 Projections from beam (J) the projections of th
26、e jaws from the edge of the beam shall be as shown in table 2. the projections J of the two jaws shall be equal to within 0.03 mm or 0.001 in, as shall projections J1. (See Figure 1.) NOTE The beam should have a minimum cross-section in accordance with Annex A. Licensed Copy: London South Bank Unive
27、rsity, South Bank University, 31/01/2009 03:44, Uncontrolled Copy, (c) BSI BritiSh Standard BSI 2008 3 BS 887:2008 Figure 1 Illustration of the components of a precision vernier caliper, and their nomenclature 02 4567 89101112 1314151617 1819 20 Ver 0.02 mm 01234 56 7 89 0 212223242526 272829303132
28、31cm 10mm A B 5 J1 J J1 J 1 3 5 6 9 11 10 7 9 10 8 4 2 NOTE This illustration is not intended to be taken as specifying a particular design. Key Beam 1 Main scale2 Slider 3 Fine adjustment clamp4 Fine adjustment5 Vernier scale6 Fixed jaw7 Guiding surface8 Faces for external measurement9 Faces for in
29、ternal measurement10 nominal combined width of the internal measuring jaws, e.g. 10 mm (see 11 5.5) Licensed Copy: London South Bank University, South Bank University, 31/01/2009 03:44, Uncontrolled Copy, (c) BSI BS 887:2008 4 BSI 2008 BritiSh Standard table 2 Projection of jaws from guiding surface
30、 of beam, J a) Metric callipers Measuring range Projection J MinimumMaximum mmmmmm 0 to 1503050 0 to 3005070 0 to 6005575 0 to 1 0006080 b) Imperial callipers Measuring range Projection J MinimumMaximum ininin 0 to 61.252 0 to 1223 0 to 1823 0 to 242.253 0 to 362.53 0 to 482.54 4.4.2 Faces for exter
31、nal measurement the lengths of the faces for external measurement shall be at least half that of projection J (see Figure 1), and the remainder of the jaws shall be relieved. the faces shall be flat to within 0.005 mm or 0.000 2 in, parallel to within 0.008 mm or 0.000 3 in and shall have a surface
32、finish no coarser than 0.1 m Ra or 4 in Ra at a cutoff value of 0.8 mm or 0.032 in. the face of the fixed jaw (a) shall be square to the guiding edge of the beam within 0.008 mm per 25 mm or 0.000 3 in per inch. these requirements shall be tested in accordance with B.2.1 to B.2.3. 4.4.3 Faces for in
33、ternal measurement the internal measuring faces shall be of cylindrical form with a radius not exceeding half their combined width. the faces shall have a surface finish of not less than 0.4 m Ra or 16 in Ra at a cutoff value of 0.8 mm or 0.032 in and shall comply with table 3 when tested in accorda
34、nce with B.2.4 and B.2.5. 4.4.4 Alignment of jaws When the sliding jaw is clamped to the beam in the zero position the surfaces of the jaws (a and B) shall be coplanar to within 0.05 mm or 0.002 in. Licensed Copy: London South Bank University, South Bank University, 31/01/2009 03:44, Uncontrolled Co
35、py, (c) BSI BritiSh Standard BSI 2008 5 BS 887:2008 4.4.5 Slider the slider shall be a good sliding fit over the full working length of the beam and a suitable fitting shall be incorporated to give fine adjustment to the slider. a clamp shall be provided on the slider so that it may be effectively l
36、ocked after fine adjustment has been made and in such a manner that the setting of the vernier scale relative to the main scale is not altered. Parallelism of the faces for external measurement shall not be affected by the clamping or locking of the slider. table 3 Faces for internal measurements (a
37、) Metric Measuring rangeMinimum length of face Minimum combined width of jaws Maximum error in Combined sizeParallelism of the faces mm mm mm mm mm 0 to 150 4 5 0 to 300 6 10 0.013a)0.01 0 to 600 6 10 0 to 1 000 6 10 (b) Imperial Measuring rangeMinimum length of face Minimum combined width of jaws M
38、aximum error in Combined sizeParallelism of the faces in in in in in 0 to 6 0.187 0.25 0.000 5a) 0.000 5 0 to 12 0.25 0.3 0 to 18 0.25 0.3 0 to 24 0.25 0.3 0 to 36 0.312 0.5 0 to 48 0.312 0.5 a) this requirement does not apply to callipers having separate scales and verniers which permit direct read
39、ing of interval and external measurements. 5 Scales 5.1 General the layout of the main scale and vernier scale shall be as shown in table 4 and Figure 3, Figure 4 and Figure 5. the graduated length of the beam shall be the nominal measuring range of the calliper plus the length of the vernier scale.
40、 Provision shall be made for resetting the zero position. Licensed Copy: London South Bank University, South Bank University, 31/01/2009 03:44, Uncontrolled Copy, (c) BSI BS 887:2008 6 BSI 2008 BritiSh Standard 5.2 Position of the scales (see Figure 1) the scales shall be on the front face of the be
41、am and shall read from left to right. Callipers shall be graduated with either one main scale or with two main scales. Callipers graduated with one main scale shall have the vernier scale positioned on the sliding jaw below the beam. “inside” measurements shall be obtained by the addition of the com
42、bined width of the internal measuring jaws to the scale reading. Callipers graduated with both “inside” and “outside” main scales shall have the vernier scales positioned on the sliding jaw above and below the beam and the vernier scale for “outside” measurements shall be on the sliding jaw below th
43、e beam. 5.3 Graduation marks the main scale and vernier scale graduation marks shall be clear and perpendicular to the edge of the beam and the width of the marks shall be not less than 0.08 mm or 0.003 in and not more than 0.18 mm or 0.007 in. the variation of line thickness shall not exceed 0.05 m
44、m or 0.002 in throughout the instrument when checked in accordance with B.3. 5.4 Fitting of vernier scale with main scale the distance from the graduated face of the beam to the edge of the graduated face of the vernier shall not exceed 0.1 mm or 0.004 in (see Figure 2). NOTE It is recommended that
45、for ease of reading the surface of the beam and the vernier should have a dull finish, and that the graduation lines and characters should be black. Licensed Copy: London South Bank University, South Bank University, 31/01/2009 03:44, Uncontrolled Copy, (c) BSI BritiSh Standard BSI 2008 7 BS 887:200
46、8 Figure 2 Distance of vernier main scale 0.1 0.1 2 3 1 AB a) Metric. dimensions are in mm. 0.004 0.004 3 2 1 AB b) imperial. dimensions are in inches. Key Beam1 Vernier2 Slider3 Licensed Copy: London South Bank University, South Bank University, 31/01/2009 03:44, Uncontrolled Copy, (c) BSI BS 887:2
47、008 8 BSI 2008 BritiSh Standard 5.5 Marking (other than graduation marks) the beam shall be marked with the unit symbol of the scale figures, i.e. either (a) mm or cm, or (b) in. NOTE Figuring in millimetres is preferred for 0 mm to 150 mm and 0 mm to 300 mm range callipers. the vernier blade shall
48、be marked with the value of a vernier division, i.e. VEr 0.02 mm or VEr 0.001 in. Where the calliper is provided with one main scale for direct inside reading and another for direct outside reading, the appropriate vernier blades shall be marked “inside” and “outside” respectively. instruments with
49、one main scale and a vernier scale shall have the fixed jaw (a) marked with the nominal combined width of the internal measuring jaws. Each calliper shall have clearly and permanently marked upon it, in characters not less than 1 mm high, the manufacturers name or trade mark. table 4 Layout of scales (a) Metric scale Main scale Vernier scale Graduations Graduations and numbering Number of divisions Length Graduations and numbering Other marking 1 mm intervals (see Fig