1、BRITISH STANDARD BS3730-1: 1987 ISO6318:1985 Assessment of departures from roundness Part1: Glossary of roundness measurement terms ISO title: Measurement of roundness Terms, definitions and parameters of roundness UDC620.166:513.113.6:001.4BS3730-1:1987 ISO6318:1985 This British Standard, having be
2、en prepared under the directionof the General Mechanical Engineering Standards Committee, was published under the authority ofthe Board of BSI and comes intoeffect on 27February1987 BSI 04-1999 First published June1964 First revision December1982 Second revision February1987 The following BSI refere
3、nces relate to the work on this standard: Committee reference GME/10 Draft for comment83/74367DC ISBN 0 580 15432 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the General Mechanical Engineering Standards Committee (GME/-) to Technical C
4、ommittee GME/10 upon which the following bodies were represented: Department of Trade and Industry (National Engineering Laboratory) Department of Trade and Industry (National Physical Laboratory) GAMBICA (BEAMA Ltd.) Gauge and Tool Makers Association Institution of Production Engineers Loughborough
5、 University of Technology Ministry of Defence University of Warwick Coopted member Amendments issued since publication Amd. No. Date of issue CommentsBS3730-1:1987 BSI 04-1999 i Contents Page Committees responsible Inside front cover National foreword ii Scope and field of application Term and defin
6、itions 1 General terms (surfaces, planes, axes) 1 2 Profiles 1 3 Reference circle 2 4 Displayed reference circle 2 5 Definitions of reference circles to be fitted to the traced profile of the workpiece, and to the displayed representation of the traced profile when adequately centred on the axis of
7、rotation 2 6 Terms relating to the circumference 2 7 Terms relating to filter function of the apparatus 3 8 Additional terms 3 Figure 1 Wavelength angle 2 Figure 2 Flowchart illustrating an example using the least squares circle 4 Figure 3 Coordinate system for roundness measurement, seen in the dom
8、ain: a) of a cylindrical workpiece; b) of its graphical representation 5BS3730-1:1987 ii BSI 04-1999 National foreword This Part of BS3730, which has been prepared under the direction of the General Mechanical Engineering Standards Committee, is identical with ISO6318-1985 “Measurement of roundness
9、Terms, definitions and parameters of roundness”, published by the International Organization for Standardization (ISO). This Part of BS3730 is a revision of BS3730-1:1982 which is withdrawn. Terminology and conventions. The text of the international standard has been approved as suitable for publica
10、tion as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. Wherever the words “International Standard” appear, referring to this standard, they should be read as “this
11、Part of BS3730”. 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
12、cument comprises a front cover, an inside front cover, pagesi andii, pages1 to5 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 the inside front cover.BS3730-1:1987 BSI 04-1999 1 Scope an
13、d field of application This International Standard defines metrological terms used in the determination of deviations from roundness. Figure 2 and Figure 3 illustrate sequential steps involved in roundness measurement. Terms and definitions 1 General terms (surfaces, planes, axes) 1.1 real surface a
14、 surface limiting the body separating it from the surrounding medium See Figure 2 1.2 nominal axis of rotation the theoretically exact axis about which the spindle of a perfect instrument rotates 1.3 instantaneous axis of rotation the axis about which the spindle of an instrument actually rotates at
15、 any instant NOTEThe instantaneous axis of rotation may be continuously varying within the confines of the bearings. 1.4 reference axis of rotation the mean of the instantaneous axes about which the spindle of an instrument rotates 1.5 instantaneous error of rotation the difference between the posit
16、ion of the instantaneous axis of rotation and the reference axis of rotation NOTEErrors of rotation of the instrument may comprise radial, axial and tilt components. 1.6 nominal plane of measurement a plane perpendicular to the nominal axis of rotation of the instrument 1.7 plane of measurement plan
17、e perpendicular to the reference axis of rotation and passing through the point of contact of the detecting element of the instrument with the workpiece 1.8 direction of measurement the direction along which radial variations are determined. It substantially intersects the axis of rotation of the in
18、strument and it generally lies in the plane of measurement 1.9 axis of workpiece a defined straight line about which the relevant part of the workpiece is considered to be round see Figure 3 NOTEThere may be several ways in which the axis can be defined, including: 1) A straight line such that the r
19、oot mean square value of the distances from it of the defined centres of a representative number of cross-sections has a minimum value. 2) A straight line passing through the defined centres of two separated and defined cross-sections. 3) A straight line which passes through the defined centre of on
20、e defined cross-section and is perpendicular to a defined shoulder. 4) A straight line passing through two support centresthis axis is independent of the surface of the workpiece. 5) An axis of two coaxial surfaces of revolution just enclosing the surface irregularities of the workpiece. 1.10 settin
21、g-up eccentricity the distance in the plane of measurement between the point of intersection therewith of the reference axis of rotation of the instrument and the defined centre of the workpiece profile 1.11 factor of amplification the ratio of the output value of the instrument to the displacement
22、of the stylus in the direction of measurement 2 Profiles 2.1 real roundness profile the profile resulting from the intersection of the real surface of a round workpiece by a plane perpendicular to its defined axis. The concept encompasses every feature of the surface, however small it may be 2.2 pro
23、file transformation the action of transforming a profile at any stage, as, for example, by a stylus, filter or recorder 2.3 traced profile the profile determined by the path followed by the sensing device (the stylus). It may, sometimes, be indistinguishable from the real roundness profile. Measured
24、 parameters of roundness are referred to the traced profile See Figure 2 NOTEIt may tend to include or exclude surface roughness according to the dimensions of the stylus.BS3730-1:1987 2 BSI 04-1999 2.4 modified profile the traced profile intentionally modified by an analogue or digital wave filter
25、having defined characteristic 2.5 displayed profile the representation of the traced or modified profile displayed by the instrument, for example as a trace, oscilloscope presentation or data log 3 reference circle a circle fitting the traced profile of the workpiece in a defined way, to which the d
26、epartures from roundness and the geometric roundness parameters are referred 4 displayed reference circle a circle representing the workpiece reference circle, fitted to the displayed representation of the traced profile in a defined way NOTE 1Residual eccentricity left after setting up will result
27、in slight distortion of the displayed representation of the workpiece profile and, in principle, the displayed reference circle should be distorted correspondingly, approximately to the shape known as a limaon. Electrical methods of plotting the reference circle on a polar graph, and digital represe
28、ntations, often do this automatically. The distortion, having a maximum value given by E 2 /2R, can generally be neglected if the residual eccentricity, E, measured at the display is kept within about15% of the mean radius, R, of the profile for general testing, and within7% for more critical applic
29、ations. NOTE 2Other reference profileselliptical, tri-lobe, electric wave filter mean linemay find auxiliary use for analytical purposes. 5 Definitions of reference circles to be fitted to the traced profile of the workpiece, and to the displayed representation of the traced profile when adequately
30、centred on the axis of rotation 5.1 least squares mean circle (LSC) a circle such that the sum of the squares of the departures from it of the traced or modified profile of the workpiece is a minimum 5.2 minimum circumscribed circle (MCC) smallest possible circle that can be fitted around the traced
31、 or modified profile of a shaft 5.3 maximum inscribed circle (MIC) largest possible circle that can be fitted within the traced or modified profile of a hole 5.4 minimum zone circles (MZC) two concentric circles enclosing the traced or modified profile and having the least radial separation 6 Terms
32、relating to the circumference 6.1 undulations per revolution; upr the number of complete periodic undulations contained in the periphery of the workpiece NOTEThere cannot be less than one complete undulation per360 or2; rad. 6.2 sinusoidal undulation number, n s the number of dominant or superimpose
33、d periodic sinusoidal waves measured during one revolution of the workpiece 6.3 sinusoidal undulation frequency sinusoidal undulation number multiplied by revolutions per second of the instrument (expressed in hertz) 6.4 wavelength angle, the reciprocal of the upr multiplied by360, when expressed in
34、 degrees, or2; when expressed in radians See Figure 1 6.5 circumferential wavelength the circumference of the workpiece divided by the upr Figure 1 wavelength angleBS3730-1:1987 BSI 04-1999 3 7 Terms relating to filter function of the apparatus 7.1 wave filter a system transmitting a range of sinuso
35、idal frequencies for which the ratio of output to input amplitude is nominally constant, while attenuating (i.e.reducing) the ratio for frequencies lying outside the range at either or both ends NOTEA characteristic of the electric wave filter is that the ratio is dependent only on frequency, and is
36、 independent of amplitude, in contrast to mechanical filtering methods (for example by the stylus) which are influenced by frequency and also by amplitude. 7.2 amplitude transmission characteristic ratio of output amplitude to input amplitude plotted for each of a range of sinusoidal frequencies cov
37、ering the operative range of the apparatus NOTEThe ratio may be expressed as a percentage or in decibels. 7.3 rate of attenuation of filter the maximum slope of the transmission characteristic NOTE 1The attenuation rate is determined by the design of the filter and is expressed in decibels per octav
38、e. NOTE 2The rate of attenuation at the75% transmission cut-off may also be significant and expressed. 7.4 phase shift the displacement, in time or space, between sinusoidal output and input signals of a given frequency NOTEThe phase shift produced by a filter, such as the two C-R 1)filter, is gener
39、ally dependent on the rate of attenuation at each frequency considered. Phase shift through a phase-corrected (digital) filter can be zero or the same for all frequencies. 7.5 undulation cut-off the number of sinusoidal undulations per360 at the upper or lower end of the passband, where the transmis
40、sion has been attenuated to75% of its maximum (except for1upr) 7.6 undulation range of the filter the range of undulations lying between the upper and lower undulation cut-off NOTEThe undulation range may be expressed in spatial terms (undulations per360) or in temporal terms (frequency in hertz). 8
41、 Additional terms 8.1 method divergence the numerical difference between two methods of measurement which are both standardized and are nominally but not precisely equal 8.2 measurement between support centres method in which the axis used for measurement is the common axis between the support centr
42、es formed in the workpiece itself NOTEIn this method the real axis of rotation of the workpiece can lead to differences in the measurement which can be caused by a) defects of form, orientation, alignment of the centres and the benchmarks; b) possible eccentricity of the section being checked. 1) “C
43、” stands for “capacitive”, “R” for “resistive”.BS3730-1:1987 4 BSI 04-1999 Figure 2 Flowchart illustrating an example using the least square circleBS 3730-1:1987 BSI 04-1999 5 Figure 3 Coordinate system for roundness measurement, seen in the domain: a) of a cylindrical workpiece; b)of its graphical
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