1、BRITISH STANDARD BS 3731:1987 Specification for Vee blocks UDC 621.751:62229.4:62431BS3731:1987 This British Standard, having been prepared under the directionof the General Mechanical Engineering Standards Committee, was published under the authority ofthe Board of BSI and comes intoeffect on 31Dec
2、ember1987 BSI 01-2000 First published March1964 First revision September1977 Second revision December1987 The following BSI references relate to the work on this standard: Committee referenceGME/8 Draft for comment84/79273DC ISBN 0 580 16137 4 Committees responsible for this BritishStandard The prep
3、aration of this British Standard was entrusted by the General Mechanical Engineering Standards Committee (GME/-) to Technical Committee GME/8, upon which the following bodies were represented: City of Birmingham Polytechnic Department of Trade and Industry (National Engineering Laboratory) Departmen
4、t of Trade and Industry (National Measurement Accreditation Service) Department of Trade and Industry (National Physical Laboratory) Gauge and Tool Makers Association Institution of Production Engineers Ministry of Defence Amendments issued since publication Amd. No. Date of issue CommentsBS3731:198
5、7 BSI 01-2000 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Nomenclature and definitions 1 3 Classification 1 4 Materials 1 5 General features 1 6 Finish 1 7 Clamps 1 8 Accuracy 2 9 Container 3 10 Protection against climatic conditions 3 11 Marking 4 Appendix A Re
6、commended general dimensions 5 Appendix B Recommended methods of testing vee blocks 6 Figure 1 Nomenclature 2 Figure 2 Hollow type vee blocks 5 Figure 3 Solid type vee blocks 5 Figure 4 Double type vee blocks 5 Figure 5 Checking the vee axis 6 Table 1 Geometrical accuracy for grade1 vee blocks 3 Tab
7、le 2 Geometrical accuracy for grade2 vee blocks 3 Table 3 Dimensions of cast iron hollow type vee blocks 5 Table 4 Dimensions of steel or cast iron solid type vee blocks 5 Table 5 Dimensions of steel or cast iron double type vee blocks 5 Table 6 Dimensions of granite vee blocks 6 Publications referr
8、ed to Inside back coverBS3731:1987 ii BSI 01-2000 Foreword This revision of BS3731 has been prepared under the direction of the General Mechanical Engineering Standards Committee. It supersedes BS3731:1977 which is withdrawn. In this revision the requirements relating to matched pairs of blocks have
9、 been altered to take account of production difficulties, and the opportunity has been taken to make certain other requirements more specific. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct appli
10、cation. 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, pagesi andii, pages1to6, an inside back cover and a back cover. This standard has been updated (see copyright date) and
11、 may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS3731:1987 BSI 01-2000 1 1 Scope This British Standard specifies requirements for hollow or solid, single or double vee blocks made from cast iron or steel and solid vee blocks made from g
12、ranite, normally with a90 included vee angle though the provisions of this standard are applicable to vee blocks with included vee angles other than90 . Two grades of accuracy,1 and2, are specified, and provision is made for matched pairs. NOTE 1Appendix A andAppendix B respectively deal with recomm
13、ended dimensions for vee blocks with a maximum capacity of200mm diameter and with methods of test. NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover. 2 Nomenclature and definitions For the purposes of this British Standard the nomenclature shown in
14、Figure 1 and the following definitions apply. 2.1 designating size the diameter of the maximum cylinder that the block will accommodate leaving1mm beyond the lines of contact 2.2 deviation from flatness the minimum distance separating two parallel planes between which the surface can just be contain
15、ed 2.3 deviation from parallelism of two surfaces the variation in distance between one of the surfaces and a datum plane when the other surface is in contact with the datum plane 2.4 deviation from squareness of two surfaces the minimum distance between two parallel planes which just enclose one su
16、rface and are perpendicular to a datum plane in contact with the other surface 2.5 working faces the vee flanks, base, top, end, and side faces 2.6 vee axis the axis of a cylinder in contact with the length of the vee flanks 3 Classification Vee blocks are classified as grade1 or2 according to their
17、 accuracy as specified in clause8. 4 Materials 4.1 Steel vee blocks The steel shall be sound and free from defects. The surface hardness shall be not less than700HV and the block shall be stabilized. 4.2 Cast iron vee blocks Close-grained cast iron not inferior to grade180 of BS1452 shall be used. T
18、he castings shall be free from blowholes or porous patches. The plugging of minor defects with a material of a similar composition is permitted provided that such a repair does not affect stability or accuracy. Grade 1 vee blocks shall be heat treated to have a hardness value of not less than500HV.
19、NOTEGrade 2 vee blocks may be hardened or left unhardened. 4.3 Granite vee blocks The granite shall be close-grained and of uniform texture and colour, sound and free from flaws and fissures and from inclusions of softer materials. 5 General features 5.1 There shall be a minimum length of vee flank
20、of1mm beyond the lines of contact with the maximum diameter cylinder. NOTEAn undercut at the bottom of the vee is permissible providing there is a minimum length of flank of1mm below the line of contact of a5mm diameter cylinder. 5.2 When threaded holes or threaded inserts are provided they shall be
21、M6 16H complying with the requirements of BS3643-2. NOTEThe positions of threaded holes or threaded inserts may be specified by the manufacturer or be as requested by the purchaser. 6 Finish 6.1 Grade 1 vee blocks shall have a ground and/or lapped finish on all working faces. Grade2 vee blocks shall
22、 be finished by a similar process or by planing, shaping or milling. 6.2 There shall be no sharp edges. 7 Clamps When clamps are supplied they shall be sufficiently robust to secure cylinders within the capacity of the vee block. NOTEIn order to facilitate the use of vee blocks when located on their
23、 side faces, it is recommended that clamps be designed so that the clamp body does not extend beyond the side faces of the block.BS3731:1987 2 BSI 01-2000 8 Accuracy 8.1 Grade 1 vee blocks Grade 1 vee blocks shall be geometrically accurate within the permitted deviations given inTable 1. Deviation o
24、f working faces from flatness shall not be such that they are convex. 8.2 Grade 2 vee blocks Grade 2 vee blocks shall be geometrically accurate within the permitted deviations given inTable 2. Deviations of working faces from flatness shall not be such that they are convex. 8.3 Matched pairs The tol
25、erances in columns2 to8 ofTable 1 andTable 2 apply to each individual block in the pair, appropriate to the grade. In addition, the variations in the pair shall not exceed the values given in column9 of the respective tables for the following features: a) heights of the vee axes above the bases; b)
26、widths between the vee axes and the preferred side faces; c) widths between the vee axes and the non-preferred side faces. Figure 1 NomenclatureBS3731:1987 BSI 01-2000 3 The preferred orientation of each block in a pair shall be indicated by the manufacturer. NOTEAttention is drawn to the fact that
27、if these latter requirements are to be met, advantage cannot be taken of the whole of the tolerances for individual blocks. 9 Container Grade1 vee blocks shall be supplied in a container. 10 Protection against climatic conditions During storage and transit steel and cast iron vee blocks shall be pro
28、tected against climatic conditions. Table 1 Geometrical accuracy for grade1 vee blocks Table 2 Geometrical accuracy for grade2 vee blocks Designating size Permitted deviations Flatness of working faces Squareness of end and side faces to the base (measured over height) Parallelism of opposite faces
29、Parallelism of vee axis to base and to side faces over length of vee a Squareness of vee axis to end faces over length of vee a Equality of semi-angles of vee flanks a Centrality of vee b Matching tolerance over the lengths of vees (see8.3) mm 4m 4m 4m 4m 4m minute 4m 4m 20 25 40 50 63 75 80 85 100
30、125 160 200 2 2 3 3 4 5 5 5 6 8 10 12 4 4 6 6 8 10 10 10 12 16 20 24 4 4 6 6 8 10 10 10 12 16 20 24 2 2 4 4 6 8 8 8 10 14 18 22 2 2 4 4 6 8 8 8 10 14 18 22 1 1 1 1 1 1 1 1 1 1 1 1 4 4 6 6 8 10 10 10 12 16 20 24 2 2 3 3 4 5 5 5 6 8 10 12 NOTEIntermediate sizes should be made to the accuracy specified
31、 for the next smaller designating size. Double vee blocks should be made to the accuracy specified for the larger designating size. a For a recommended method of checking these features, seeAppendix B. b Displacement of the centre of the vee axis from the centre line between the two side faces. Desi
32、gnating size Permitted deviations Flatness of working faces Squareness of end and side faces to the base (measured over height) Parallelism of opposite faces Parallelism of vee axis to base and to side faces over length of vee a Squareness of vee axis to end faces over length of vee a Equality of se
33、mi-angles of vee flanks a Centrality of vee b Matching tolerance over the lengths of vees (see8.3) mm 4m 4m 4m 4m 4m minute 4m 4m 20 25 40 63 80 85 100 125 160 200 6 6 8 12 16 16 18 24 26 28 8 10 14 26 34 34 38 40 42 46 8 10 14 26 34 34 38 40 42 46 8 10 14 26 34 34 38 40 42 46 8 10 14 26 34 34 38 40
34、 42 46 2 2 2 2 2 2 2 2 2 2 6 8 10 18 22 22 24 24 26 28 4 4 6 8 10 10 12 16 20 24 NOTEIntermediate sizes should be made to the accuracy specified for the next smaller designating size. Double vee blocks should be made to the accuracy specified for the larger designating size. a For a recommended meth
35、od of checking these features, seeAppendix B. b Displacement of the centre of the vee axis from the centre line between the two side faces.BS3731:1987 4 BSI 01-2000 11 Marking Each vee block shall be legibly and permanently marked with the following information in a manner that does not affect the a
36、ccuracy of the vee block: a) the manufacturers name or trade mark; b) the number and date of this British Standard,i.e.BS3731 1) ; c) the grade of accuracy (grade1 or grade2); d) matched pairs of vee blocks shall bear a suitable pairing symbol,e.g.A andB. NOTE 1All vee blocks that are to be certifie
37、d by a testing authority are required to bear a serial number. NOTE 2It is recommended that the designating size be marked on the block. 1) Marking BS3731 on or in relation to a product represents a manufacturers declaration of conformity,i.e. a claim by or on behalf of the manufacturer that the pro
38、duct meets the requirements of the standard. The accuracy of the claim is therefore solely the responsibility of the person making the claim. Such a declaration is not to be confused with third party certification of conformity, which may also be desirable.BS3731:1987 BSI 01-2000 5 Appendix A Recomm
39、ended general dimensions Recommended general dimensions for steel and cast iron vee blocks are given inTable 3,Table 4 andTable 5. Because of the nature of the material, special consideration has been given to granite vee blocks and recommended general dimensions are given inTable 6. Table 3 Dimensi
40、ons of cast iron hollow type vee blocks (seeFigure 2) Table 4 Dimensions of steel or cast iron solid type vee blocks (seeFigure 3) Table 5 Dimensions of steel or cast iron double type vee blocks (seeFigure 4) Designating size D Width A Height B Length C mm mm mm mm 63 80 100 125 160 200 80 100 130 1
41、50 180 220 60 75 90 100 130 160 35 40 45 50 60 70 Figure 2 Hollow type vee blocks Designating size D Width A Height B Length C mm mm mm mm 40 85 50 100 40 70 25 50 Figure 3 Solid type vee blocks Designating sizes D Width A Height B Length C mm mm mm mm 20 and 25 20 and 40 32 40 32 40 42 50 Figure 4
42、Double type vee blocksBS3731:1987 6 BSI 01-2000 Table 6 Dimensions of granite vee blocks (seeFigure 3) Appendix B Recommended methods of testing vee blocks B.1 Vee axis B.1.1 Parallelism of the vee axis to the base can be determined from indicator readings taken over the ends of a precision cylinder
43、 placed in the vee seeFigure 5a). The cylinder should extend beyond the end faces of the block. B.1.2 Parallelism of the vee axis to the side faces and its centrality can be determined in a similar manner, but using the side faces in turn as a datum seeFigure 5b). B.1.3 Squareness of the vee axis to
44、 the end faces can be determined using a precision cylinder, with a flange or tee piece, using the end faces in turn as a datum seeFigure 5c). Squareness should be determined in two planes at90,i.e.parallel to the base and parallel to the side faces. NOTEAny error in squareness of the flange or tee
45、piece to the precision cylinder can be determined by rotating the cylinder through180 . B.2 Equality of matched pairs A method similar to that described inB.1.1 is also recommended for checking the heights of the vee axes above the base in matched pairs of vee blocks (see8.3), but in this case heigh
46、t readings should be taken over the minimum and maximum cylinders that can be accommodated by the blocks in question. Measurement of the widths between the vee axes and side faces over the length of the vees can also be determined by means of these cylinders. B.3 Equality of semi-angles Equality of
47、the semi-angles of the vee is conveniently checked by means of a sine table and test indicator. Designating size D Width A Height B Length C mm mm mm mm 50 75 85 125 75 100 150 200 75 100 150 200 75 100 150 200 Figure 5 Checking the vee axisBS3731:1987 BSI 01-2000 Publications referred to BS 817, Sp
48、ecification for surface plates. BS 1452, Specification for grey iron castings. BS 3643, ISO metric screw threads. BS 3643-2, Specification for selected limits of size. BS 3731:1987 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsibl
49、e for preparing BritishStandards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions BritishStandards are updated by amendment or revision. Users of BritishStandards 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 finding an inaccuracy or ambiguity while using this BritishStandard would inform the Secretar
