1、BRITISH STANDARD BS3730-3: 1982 Assessment of departures from roundness Part3: Methods for determining departures from roundness using two- and three-point measurement UDC 531.717.2:621.7.08BS3730-3:1982 This British Standard, having been prepared under the directionof the Mechanical Engineering Sta
2、ndards Committee, was published underthe authority of the BoardofBSI and comes intoeffecton 31December1982 BSI05-1999 First published June1964 First revision December1982 The following BSI references relate to the work on this standard: Committee reference MEE/69 Draft for comment81/73682 DC ISBN 0
3、580 12968 3 Cooperating organizations The Mechanical Engineering Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following: Associated Offices Technical Committee Department of Trade (Marine Division) Association of Consulting Engin
4、eers Department of Transport Association of Hydraulic Equipment Electricity Supply Industry in England Manufacturers and Wales Association of Mining Electrical and Energy Industries Council Mechanical Engineers Engineering Equipment Users Association British Compressed Air Society Federation of Manu
5、facturers of Construction British Constructional Steelwork Association Equipment and Cranes British Electrical and Allied Manufacturers Health and Safety Executive Association (BEAMA) Institution of Gas Engineers British Gas Corporation Institution of Mechanical Engineers British Gear Manufacturers
6、Association Institution of Plant Engineers British Internal Combustion Engine Institution of Production Engineers* Manufacturers Association Lloyds Register of Shipping British Pump Manufacturers Association London Transport Executive British Steel Corporation Machine Tool Industry Research Associat
7、ion British Steel Industry Ministry of Defence* British Valve Manufacturers Association Ltd. National Coal Board Chartered Institution of Building Services Oil Companies Materials Association Crown Agents for Oversea Governments and Process Plant Association Administrations Society of Motor Manufact
8、urers and Department of Industry (Mechanical Traders Limited Engineering) Telecommunication Engineering and Department of Industry (National Manufacturing Association (TEMA) Engineering Laboratory) Water-tube Boilermakers Association Department of the Environment (PSA) The organizations marked with
9、an asterisk in the above list, together with the following, were directly represented on the Technical Committee entrusted with the preparation of this British Standard: Gauge and Tool Makers Association University of Salford Production Engineering Research University of Warwick Association of Great
10、 Britain Coopted member Scientific Instrument Manufacturers Association Amendments issued since publication Amd. No. Date of issue CommentsBS3730-3:1982 BSI 05-1999 i Contents Page Cooperating organizations Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Measuring conditions and instrumen
11、t 1 4 Procedure 2 5 Expression of results 2 Appendix A Worked examples 8 Figure 1 Two-point measurement 2 Figure 2 Three-point measurement, summit method, symmetrical setting 2 Figure 3 Three-point measurement, summit method, asymmetrical setting 3 Figure 4 Three-point measurement, rider method, sym
12、metrical setting 3 Figure 5 Two-point measurement 3 Figure 6 Three-point measurement, summit method, symmetrical setting 3 Figure 7 Three-point measurement, summit method, asymmetrical setting 3 Figure 8 Three-point measurement, rider method, symmetrical setting 3 Table 1 Types of anvil 1 Table 2 Va
13、lues of factor F for =90 and =120, symmetrical setting 4 Table 3 Values of factor F for =72 and =108, symmetrical setting 4 Table 4 Values of factor F for =60/=30 and =120/=60, asymmetrical setting and =90, symmetrical setting 5 Table 5 Values of factor F for =90 and =120, symmetrical setting, for n
14、 s =2 to n s =22 6 Table 6 Values of factor F for =72 and =108, symmetrical setting, for n s =2 to n s =22 6 Table 7 Values of factor F for =60/=30 and =120/=60, asymmetrical setting, for n s =2 to n s =22 7 Table 8 Values of factor F for =60, symmetrical setting, for n s= 2 to n s= 22 7 Publication
15、s referred to Inside back coverBS3730-3:1982 ii BSI 05-1999 Foreword This Part of this British Standard has been prepared under the direction of the Mechanical Engineering Standards Committee. It takes account of discussions within ISO/TC57 Metrology and properties of surfaces, the results of which
16、will be published as ISO4292. At the time of publication the technical content of this Part of this standard was in agreement with the ISO draft. Appendix A gives worked examples of calculations for the departure from roundness. This standard together with Parts1 and 2 supersedes BS3730:1964 which i
17、s now withdrawn. 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 obligations. Summary of pages This do
18、cument comprises a front cover, an inside front cover, pagesi andii, pages1 to8, 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 theinside front cover.BS3730-3:1982 B
19、SI 05-1999 1 1 Scope This Part of this British Standard describes methods for the numerical assessment of departures from roundness by the combination of two- and three-point measurement. The following methods are dealt with: a) determination by means of two-point measurement (measurement of diamete
20、rs); b) determination by means of three-point measurement, summit (symmetrical or asymmetrical setting); c) determination by means of three-point measurement, rider (symmetrical setting). Any statement regarding an out-of-round section is incomplete unless the extent and nature of the departures fro
21、m roundness is given and this is dealt with in Appendix A to D of BS3730-2:1982. For routine or in-process inspection, the requirements of BS3730-2 may either be needlessly accurate or the items to be inspected may be too large to be accommodated. The methods described in this Part of this standard
22、may give faster and cheaper ways of assessing departures from roundness. This assessed value will deviate from the true value. The difference between the measured value and the true value can be estimated with help of Table 2 toTable 8, under the presumption that the undulation numbers are known and
23、 of sinusoidal nature. For non-sinusoidal undulations, a theory for estimating such deviations is not yet available. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this Part of BS3730 the definitions given in Par
24、t1 apply, together with the following. 2.1 two-point measurement measurement between coaxial anvils, one fixed and one moving in the direction of measurement (seeFigure 1 and Figure 5) 2.2 three-point measurement measurement between anvils, two fixed and one moving in the direction of measurement (s
25、eeFigure 2, Figure 3, Figure 4, Figure 6, Figure 7 and Figure 8) 2.3 summit method a three-point measurement in which the two fixed anvils are situated on one side and the measuring anvil is situated on the other side of the workpiece axis in the plane of measurement (seeFigure 2, Figure 3, Figure 6
26、, and Figure 7) 2.4 rider method a three-point measurement in which the two fixed anvils are situated on the same side as the measuring anvil in the plane of measurement (seeFigure 4 and Figure 8) 2.5 symmetrical (three-point) setting a setting at which the direction of measurement coincides with th
27、e bisector angle between fixed anvils (seeFigure 2, Figure 4, Figure 6 and Figure 8) 2.6 asymmetrical (three-point) setting a setting at which the direction of measurement constitutes an angle with the bisector angle between fixed anvils (seeFigure 3 and Figure 7) 3 Measuring conditions and instrume
28、nt 3.1 Measuring anvil static force. The static measuring force shall not exceed1N. NOTE 1Preferably, the force should be adjustable and set at the lowest value that will ensure continuous contact between anvil and the surface being measured. NOTE 2For thin-walled workpieces, a high measuring force
29、may affect the measuring result. Therefore it is necessary to reduce the force to the minimum value possible. 3.2 Measuring anvils. Depending on the form of the object, the measuring anvil shall be selected from Table 1. NOTEWhere the form of the object precludes the use of the anvils given in Table
30、 1, other anvils may be used. Table 1 Types of anvil Surface form Anvil radius Surface radius mm mm Convex surface Convex edge Spherical:2.5 Cylindrical:2.5 All All Concave surface Concave edge Spherical:2.5 Cylindrical:2.5 10 10 Concave surface Concave edge Spherical:0.5 Cylindrical:0.5 10 10BS3730
31、-3:1982 2 BSI 05-1999 3.3 Fixed anvils. Point or line contact shall always be used. NOTEThe following is recommended: a) External measurement. V-support with a small radius. The median plane of the V-support should be in the same plane as the plane of measurement. b) Internal measurement. Sphere wit
32、h a small radius. The median plane of the sphere should be in the same plane as the plane of measurement. 4 Procedure In order to cover all possible form deviations and numbers of undulations always take one two-point measurement and two three-point measurements at different angles between fixed anv
33、ils. NOTEThe measurement procedures may, under certain preconditions, be amplified (seeTable 2, Table 3 and Table 4). Select the angles between fixed anvils from the following: symmetrical setting: =90 and120 or =72 and108; asymmetrical setting: 120, =60, or =60, 30; where 5 Expression of results Ca
34、lculate the corrected value of the departure from roundness from the formula: where If the three-point measurement with symmetrical setting at60 angles between fixed anvils is used when measuring workpieces with a known even or odd number of undulations, use the factor F given in Table 8. NOTEThis a
35、ngle is useful as it gives measured values of higher correction factors than the other angles in this standard. Table 5, Table 6 and Table 7 give true factors F for any given number of sinusoidal undulations and measuring method and if the number of sinusoidal undulations is known, calculate the dep
36、arture from roundness by using the F factors directly from Table 5, Table 6 or Table 7 as indicated in Table 2, Table 3 or Table 4. it is not possible to calculate exactly the departure from roundness if the number of undulations is unknown and in these cases calculate a maximum, average and minimum
37、 value of from the formula above using the largest value and the factors obtained from Table 2, Table 3 or Table 4. When selecting F, determine the limit on the maximum number of undulations per revolution, according to whether the number of undulations is known and whether this number is an odd or
38、even value, from Table 2, Table 3 and Table 4. NOTE 1For90 and120 settings the maximum number of undulations per revolution is22, which assumes that a greater number of undulations than this will not have any appreciable effect on the F factor. For72 and108 settings the maximum number of undulations
39、 per revolution is determined by the fact that for19 undulations the F factor cannot be determined. NOTE 2When using Table 5 to Table 8 other combinations of setting, besides those given in Table 2 to Table 4 can be made. is the angle between fixed anvils; is the angle between the direction of measu
40、rement and bisector of angle between fixed anvils. is the measured departure from roundness, which is largest value obtained from the preceding two or three combinations of angles received in the required measurements; F is the correction factor, with a value extracted from Table 2 to Table 8: as a
41、first approximation F may be given a value of2. F - = Figure 1 Two-point measurement Figure 2 Three-point measurement, summitmethod, symmetrical settingBS3730-3:1982 BSI 05-1999 3 Figure 3 Three-point measurement, summitmethod, asymmetrical setting Figure 4 Three-point measurement, ridermethod, symm
42、etrical setting Figure 5 Two-point measurement Figure 6 Three-point measurement, summitmethod, symmetrical setting Figure 7 Three-point measurement, summitmethod, asymmetrical setting Figure 8 Three-point measurement, ridermethod, symmetrical settingBS3730-3:1982 4 BSI 05-1999 Table 2 Values of fact
43、or F for =90 and =120, symmetrical setting Table 3 Values of factor F for =72 and =108, symmetrical setting Number of undulations, n s Combination of settings a 2, 3S90 and 3S 120 2, 3R90 and 3R 120 2 3S90 and 3S 120 3R90 and 3R 120 Factor, F n sunknown, but assumed to be 2 n s 22 max. 2.41 av. 1.94
44、 min. 1.00 max. 2.41 av. 1.96 min. 1.00 n seven but unknown, but assumed to be 2 n s 22 2.00 max. 2.41 av. 2.08 min. 2.00 max. 2.41 av. 2.17 min. 1.58 n sodd but unknown, but assumed to be 3 n s 21 max. 2.00 av. 1.80 min. 1.00 max. 2.00 av. 1.80 min. 1.00 n sknown and even 2.00 exact b exact b n skn
45、own and odd exact b exact b a The abbreviations in the table represent the following situations: 2 = two-point measurement; 3S 90 = three-point measurement, summit, = 90; 3S 120 = three-point measurement, summit, = 120; 3R 90 = three-point measurement, rider, = 90; 3R 120 = three-point measurement,
46、rider, = 120. b If multiplied by F factors given in Table 5. Number of undulations, n s Combination of settings a 2, 3S72 and 3S 108 2, 3R72 and 3R 108 2 3S72 and 3S 108 3R72 and 3R 108 Factor, F n sunknown, but assumed to be 2 n s 18 max. 2.70 av. 2.16 min. 2.00 max. 2.62 av. 2.11 min. 1.38 n seven
47、 but unknown, but assumed to be 2 n s 22 2 max. 2.70 av. 2.16 min. 2 max. 2.70 av. 2.13 min. 2 n sodd but unknown, but assumed to be 3 n s 17 max. 2.62 av. 2.06 min. 1.38 max. 2.62 av. 2.06 min. 1.38 n sknown and even 2 exact b exact b n sknown and odd exact b exact b a The abbreviations in the tabl
48、e represent the following situations: 2=two-point measurement; 3S72 =three-point measurement, summit, =72; 3S108 =three-point measurement, summit, =108; 3R72=three-point measurement, rider, =72; 3R108=three-point measurement, rider, =108; b If multiplied by F factors given in Table 6.BS3730-3:1982 BSI 05-1999 5 Table 4 Values of factor F for =60/=30 and =120/ =60, asymmetrical settingand =90 symmetrical setting Number of undulations, n s Combination of settings a 2, and 3S 60/30 2, and 3S 60/30 and 3S 90 2, and 3S 120/60 2, and 3S 120/60 and 3S 90 2 3S 60/30 3S 120/60 Factor,
