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1、BRITISH STANDARD BS 6808-1: 1987 Coordinate measuring machines Part1: Glossary of terms BS 6808-1:1987 This British Standard, having been prepared under the direction of the General Mechanical Engineering Standards Committee, was published under the authority of the Board of BSI and comes into effec
2、t on 27 February 1987 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference GME/28 Draft for comment 85/76848DC ISBN 0 580 15771 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the General Mechan
3、ical Engineering Standards Committee (GME/-) to Technical Committee GME/28 upon which the following bodies were represented: Advanced Manufacturing Technology Research Institute British Telecommunications plc Cranfield Institute of Technology Department of Trade and Industry (National Engineering La
4、boratory) Department of Trade and Industry (National Physical Laboratory) Gauge and Tool Makers Association Institution of Production Engineers Ministry of Defence Society of British Aerospace Companies Limited University of Manchester Institute of Science and Technology Amendments issued since publ
5、ication Amd. No.Date of issueComments BS 6808-1:1987 BSI 07-1999i Contents Page Committees responsibleInside front cover Forewordii 1General1 2Types of coordinate measuring machine2 3Mechanical artefacts for calibration10 4Calibration procedures11 5Measurement11 6Geometry12 7Components13 Index14 Fig
6、ure 1 Cantilever coordinate measuring machine2 Figure 2 Column coordinate measuring machine3 Figure 3 Moving horizontal arm coordinate measuring machine4 Figure 4 Fixed horizontal arm coordinate measuring machine5 Figure 5 Gantry coordinate measuring machine6 Figure 6 L-shaped bridge coordinate meas
7、uring machine7 Figure 7 Fixed bridge coordinate measuring machine8 Figure 8 Moving bridge (portal) coordinate measuring machine9 Publications referred toInside back cover BS 6808-1:1987 ii BSI 07-1999 Foreword This Part of BS 6808 has been prepared under the direction of the General Mechanical Engin
8、eering Standards Committee at the request of manufacturers and users of coordinate measuring machines (CMMs). This Part of BS 6808 defines the terms used in Part 21), whilst Part 31) is a code of practice and gives guidance on the implementation of Part 2. The terms which are defined relate to CMMs
9、themselves, but further terms are to be added which will cover the associated computer software. 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 doe
10、s not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 14, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. T
11、his will be indicated in the amendment table on the inside front cover. 1) In preparation. BS 6808-1:1987 BSI 07-19991 This Part of BS 6808 defines terms relating to coordinate measuring machines. NOTEThe titles of the publications referred to in this Part of BS 6808 are listed on the inside back co
12、ver. 1 General No.TermDefinition 101coordinate measuring machine (CMM) A machine having a series of movable members, a sensing probe and a workpiece support member, which can be operated in such a way that the probe can be brought into a fixed and known relationship with points on the workpiece surf
13、ace, and the coordinates of these points can be displayed or otherwise determined with respect to the origin of the coordinate system. NOTEIn most cases the coordinate system is a rectangular or Cartesian one, but a polar or cylindrical system may be used. 102computer controlled coordinate measuring
14、 machine A coordinate measuring machine that has the capability of performing a pre-programmed measurement sequence automatically under the control of a computer. 103manually operated coordinate measuring machine A coordinate measuring machine where the measurement procedures are under direct human
15、control and where operations are performed by hand. BS 6808-1:1987 2 BSI 07-1999 2 Types of coordinate measuring machine NOTEThere are a very large number of possible machine configurations and those types listed in 2.01 to2.08 are by no means exhaustive. However, the configurations described are a
16、sample of those in common usage. No.TermDefinition 201cantilever coordinate measuring machine A coordinate measuring machine employing three movable components moving along mutually perpendicular guideways in which the probe is attached to the first component which is carried on, and moves verticall
17、y relative to, the second; the combined assembly of the first and second components moves horizontally relative to the third; the third component is supported at one end only, cantilever fashion, and moves horizontally relative to the machine base, and the workpiece is supported on the base. NOTESee
18、 Figure 1. Figure 1 Cantilever coordinate measuring machine BS 6808-1:1987 BSI 07-19993 No.TermDefinition 202column coordinate measuring machine A coordinate measuring machine employing two movable components in which the probe is attached to the first component which moves vertically relative to th
19、e machine base; the second component is mounted on, and moves in a horizontal plane relative to, the machine base, and the workpiece is mounted on the second component. NOTESee Figure 2. Figure 2 Column coordinate measuring machine BS 6808-1:1987 4 BSI 07-1999 No.TermDefinition 203moving horizontal
20、arm coordinate measuring machine A coordinate measuring machine employing three movable components moving along mutually perpendicular guideways in which the probe is attached to the first component which is carried on, and moves horizontally relative to, the second component; the combined assembly
21、of the first and second components moves vertically relative to the third component; the third component moves horizontally relative to the machine base, and the workpiece is mounted on the machine base. NOTESee Figure 3. Figure 3 Moving horizontal arm coordinate measuring machine BS 6808-1:1987 BSI
22、 07-19995 No.TermDefinition 204fixed horizontal arm coordinate measuring machine A coordinate measuring machine employing three movable components moving along mutually perpendicular guideways in which the probe is attached to the first component which is supported horizontally at one end only, cant
23、ilever fashion, and is carried on, and moves vertically relative to, the second; the combined assembly of the first and second components and the third component move horizontally relative to the machine base, and the workpiece is mounted on the third component. NOTESee Figure 4. Figure 4 Fixed hori
24、zontal arm coordinate measuring machine BS 6808-1:1987 6 BSI 07-1999 No.TermDefinition 205gantry coordinate measuring machine A coordinate measuring machine employing three movable components moving along mutually perpendicular guideways in which the probe is attached to the first component which is
25、 carried on, and moves vertically relative to, the second; the combined assembly of the first and second components moves horizontally relative to the third; the third component moves horizontally on two guide rails raised above the machine base on either side and the workpiece is supported on the b
26、ase. NOTESee Figure 5. Figure 5 Gantry coordinate measuring machine BS 6808-1:1987 BSI 07-19997 No.TermDefinition 206L-shaped bridge coordinate measuring machine A coordinate measuring machine employing three movable components moving along mutually perpendicular guideways in which the probe is atta
27、ched to the first component which is carried on and moves vertically relative to the second; the combined assembly of the first and second components moves horizontally relative to the third; the third component moves horizontally on two guide ways, one at the base level or below, the other raised a
28、bove the base, and the workpiece is supported on the base. NOTESee Figure 6. Figure 6 L-shaped bridge coordinate measuring machine BS 6808-1:1987 8 BSI 07-1999 No.TermDefinition 207fixed bridge coordinate measuring machine A coordinate measuring machine employing three movable components moving alon
29、g mutually perpendicular guideways in which the probe is attached to the first component which is carried on, and moves vertically relative to, the second; the combined assembly of the first and second components moves horizontally along a bridge structure above, and rigidly attached at each end to,
30、 the machine base, and the workpiece is mounted on the third component. NOTESee Figure 7. Figure 7 Fixed bridge coordinate measuring machine BS 6808-1:1987 BSI 07-19999 No.TermDefinition 208moving bridge (portal) coordinate measuring machine A coordinate measuring machine employing three movable com
31、ponents moving along mutually perpendicular guideways in which the probe is attached to the first component which is carried on, and moves vertically relative to, the second; the combined assembly of the first and second components moves horizontally relative to the third; the third component is sup
32、ported on two legs, which reach down to opposite sides of the machine base, and moves horizontally relative to the base, and the workpiece is supported on the base. NOTESee Figure 8. Figure 8 Moving bridge (portal) coordinate measuring machine BS 6808-1:1987 10 BSI 07-1999 3 Mechanical artefacts for
33、 calibration No.TermDefinition 301ball-ended barA gauge consisting of two spheres of the same nominal diameter mounted at the ends of a connecting rigid bar. 302ball-plateA mechanical artefact comprising a number of spheres mounted in fixed positions on the plate, usually in a single plane. 303gauge
34、 blockA mechanical artefact with an accurately known length between its two flat and parallel end faces. NOTEThe blocks are often rectangular in cross section and less than 100 mm in length (see BS 888 or BS 4311-1 for a more detailed description). 304hole-plateA mechanical artefact that comprises a
35、 flat plate pierced with holes whose axes are normal to one of the surfaces. 305length barA mechanical artefact with an accurately known length between its two flat and parallel end faces. NOTELength bars are often circular in cross section and greater than 100 mm in length (see BS 1790 and BS 5317
36、for a more detailed description). 306material measureA measuring instrument reproducing in a permanent fashion during its use one or more known values of a given quantity for example, a gauge block for length. 307space frameA mechanical artefact in which the coordinates of a number of points in thre
37、e-dimensional space within the work zone of a coordinate measuring machine are established by reference to points on the space frame. 308squareA mechanical artefact with accurately known squareness. NOTESee BS 939 for a more detailed description. 309step gauge (uni- and bi-directional) A gauge compr
38、ising a rigid bar with calibrated features used for determining the accuracy of distance measurements in the direction of linear motion. NOTESome gauges can only be probed from one direction, others are constructed such that probing can be performed from both directions. 310straightedgeA mechanical
39、artefact with accurately known straightness along one or more of its edges. NOTESee BS 5204 for a more detailed description. 311transfer standardA one-, two- or three-dimensional artefact used as an intermediary to compare measurement standards, material measures or measuring instruments. BS 6808-1:
40、1987 BSI 07-199911 4 Calibration procedures 5 Measurement 401reversalA measurement procedure in which the test surface is measured by operating the probe in one direction and then rotating the component through 180 and measuring the same test surface by operating the same probe in the opposite direc
41、tion. NOTEIf, for example, the straightness of a component is to be measured, the test surface is first measured in the line of the axis under consideration. The component is then rotated through 180 along the measurement axis and the same test surface measured with the same probe, operating in the
42、opposite direction. By combining the two sets of results obtained by summation and subtraction the straightness of the component and of the coordinate measuring machine can be separately determined. By extending the technique to two axes, squareness may also be measured. 402stagingThe moving of a ga
43、uge from a first position to a second position such that a series of measurements started in the first position may be continued in the second position with the results related to the first. 501Abbe errorAn error in a measuring slide system, resulting from an angular error of movement of the slide,
44、that causes a relative displacement between the slide measuring scale and the probe operating on the measuring line and that is proportional to the Abbe offset and the angular error of the slide. 502Abbe offsetThe value of the perpendicular distance between the measurement system of a coordinate mea
45、suring machine, and that point on the line of measurement where the workpiece measurement takes place. 503cosine errorThe measurement error in the motion direction caused by angular misalignment between a linear displacement measuring system and the gauge being measured. 504discriminationThe quantit
46、y that characterizes the ability of a measuring instrument to react to small changes of the quantity being measured. 505errorThe algebraic difference between the result of a measurement of a dimension minus the (conventional) true value of the dimension measured. 506hysteresisThe difference between
47、the indications of a measuring instrument when the same value of the quantity measured is reached by increasing or decreasing that quantity. 507measuring lineA line in the work zone of a coordinate measuring machine along which measurements are made. 508measuring pointA point on the surface of the w
48、orkpiece at which the coordinates of the coordinate measuring machine are recorded as part of the measurement. 509random uncertaintyAn error that varies in an unpredictable manner in absolute value and in sign when a large number of measurements of the same value of a quantity are made under effecti
49、vely identical conditions. BS 6808-1:1987 12 BSI 07-1999 6 Geometry No.TermDefinition 510repeatabilityThe closeness of the agreement between the results of successive measurements of the same measurand carried out subject to all of the following conditions: the same method of measurement; the same observer; the same measuring instrument; the same location; the same conditions of use; repetition over a short period of time. 511systematic errorAn error which, in the course of a number of measurements of the same quantity made und