1、BRITISH STANDARD BS 1054:1975 Specification for Engineers comparators for external measurement UDC 621.753.3:531.713BS1054:1975 This British Standard, having been approved by the Mechanical Engineering Industry Standards Committee, was published under the authority of the Executive Board on 30 June
2、1975 BSI 06-1999 First published July 1942 First revision September 1954 Second revision 30 June 1975. The following BSI references relate to the work on this standard: Committee reference MEE/59 Draft for comment 73/33653 DC ISBN 0 580 08804 9 Co-operating organizations The Mechanical Engineering I
3、ndustry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and professional and industrial organizations: Associated Offices Technical Committee Department of Trade Association of Consulting Engineers
4、 Electricity Supply Industry in England and Association of Hydraulic Equipment Wales Manufacturers Ltd. Engineering Equipment Users Association Association of Mining, Electrical and Federation of Manufacturers of Construction Mechanical Engineers Equipment and Cranes British Compressed Air Society I
5、nstitution of Gas Engineers British Electrical and Allied Manufacturers Institution of Heating and Ventilating Association Engineers British Gas Corporation Institution of Mechanical Engineers British Gear Manufacturers Association Institution of Plant Engineers British Internal Combustion Engine In
6、stitution of Production Engineers* Manufacturers Association London Transport Executive British Mechanical Engineering Confederation Machine Tool Trades Association British Pump Manufacturers Association Ministry of Defence* British Steel Corporation National Coal Board British Steel Industry Proces
7、s Plant Association Crown Agents for Oversea Governments and Railway Industry Association of Great Britain Administrations Royal Institute of British Architects Department of Employment (HM Factory Society of Motor Manufacturers and Inspectorate) Traders Ltd. Department of the Environment Telecommun
8、ication Engineering and Department of Industry Manufacturing Association Department of Industry National Engineering Laboratory The Government department and scientific and industrial organization marked with an asterisk in the above list, together with the following, were directly represented on th
9、e committee entrusted with the preparation of this British Standard: Department of Industry National Physical Gauge and Toolmakers Association Laboratory Joint Equipment Standardization Committee Department of Prices and Consumer Protection British Calibration Services Amendments issued since public
10、ation Amd. No. Date of issue CommentsBS1054:1975 BSI 06-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Design features 1 4 Work table 1 5 Measuring tip 1 6 Operating force 2 7 Pointer 2 8 Scale 2 9 Performance 3 10 Marking 3 Figure 1 Deviat
11、ion from flatness 1 Figure 2 Scale 2 Table 1 Tolerances on consistency of reading 3BS1054:1975 ii BSI 06-1999 Foreword This British Standard is one of the series of standards for engineers precision measuring equipment for which metric versions are now being issued. It was first published as BS 1054
12、 in 1942 and revised in 1954. As in the case of earlier editions, this standard is concerned mainly with the accuracy of performance of comparators and touches on features of design only where these are likely to have a direct effect on the accuracy. A British Standard does not purport to include al
13、l 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 document comprises a front cover, an inside front cover, pages i and
14、 ii, pages1to3 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.BS1054:1975 BSI 06-1999 1 1 Scope This British Standard specifies requirements for comparators having
15、 magnification factors of 250 and over. The type of comparator to which the requirements are primarily intended to apply is an instrument comprising a rigid stand supporting a measuring head over a work table. The measuring head is provided with a measuring tip whose movements are amplified and indi
16、cated on a scale in metric units. The means of amplification may be mechanical, electrical, electronic, optical, fluid or pneumatic. 2 Definitions For the purposes of this standard, the following definitions apply. 2.1 deviation from flatness the minimum distance between two parallel planes which ju
17、st envelop the measuring face (see Figure 1) NOTEIt may be necessary to control the maximum slope of the surface deviations with respect to the enclosing planes. 2.2 flatness tolerance the maximum permissible deviation from flatness 3 Design features The instrument shall be of rigid construction and
18、 first class workmanship throughout. Particular attention should be paid to the rigidity of the vertical post or bracket which carries the measuring head and to the method of supporting the work table. The distance between the measuring head and work table shall be adjustable to suit workpieces of d
19、ifferent sizes within the stated capacity of the instrument. The base shall be of rigid construction and shall be provided with three feet. It should provide facilities for interchanging work tables. The measuring head shall be provided with a coarse adjustment for the accommodation of work within t
20、he capacity of the instrument. This coarse adjustment shall be smooth in operation and be provided with means of preventing free falling movement of the measuring head in the unclamped position. Means shall also be provided for finely adjusting the relative position of the measuring head to the work
21、 table and for clamping this fine adjustment in such a way as to ensure that the setting is maintained within one tenth of a division of the scale. The mechanism within the measuring head shall be provided with effective means of preventing damage to it in the event of the measuring tip being raised
22、 abnormally or suddenly released. 4 Work table The work table shall be made of steel or of an alternative material of comparable wearing properties, for example, of granite or of steel with tungsten carbide inserts, with or without grooves. Steel work tables shall be hardened over the working surfac
23、e to not less than HV850 (RockwellC63) and, after hardening, shall be suitably heat treated to give stability. The surface of the work table shall be finished by lapping and shall be flat to within the following tolerances. The tolerances specified for flatness shall apply tothe full working surface
24、 when the work table is75mm in diameter or smaller and to any area75mm in diameter for larger work tables. Any deviation from flatness shall be such as to give a convex configuration (see Figure 1). The lower surface of the work table, where it is a working surface, shall be parallel to the upper su
25、rface to within 0.01 mm per 25 mm. 5 Measuring tip The measuring tip shall be of hardened steel having a hardness of not less than HV850 or shall be of an alternative material of comparable wearing properties. The face of the measuring tip shall normally be rounded; a minimum radius of 8 mm is recom
26、mended. For comparators having a magnification factor of 600 or less: 0.001 mm For comparators having a magnification factor of over 600 and up to 10 000: 0.0005 mm For comparators having a magnification factor greater than 10 000: 0.0003 mm Figure 1 Deviation from flatnessBS1054:1975 2 BSI 06-1999
27、If a flat face is fitted, means shall be provided whereby the user is able to adjust the face of the tip so that the required degree of parallelism can be obtained between the tip and the surface of the work table. The measuring tip may be provided with a raising device. 6 Operating force It is reco
28、mmended that the force applied to the measuring tip to obtain zero reading on the instrument be of the order of 2 N to 2.5 N. If a measuring force substantially different from this is required, it shall be stated in the purchasers order. The operating force shall be substantially constant throughout
29、 the working range; the maximum force shall not be more than 50 % greater than the minimum for instruments having magnification factors below 3000 nor more than 25 % greater than the minimum for instruments having magnifications greater than 3000. 7 Pointer In dial reading instruments, the pointer s
30、hall be rigidly attached to its spindle in such a manner as to ensure that there will be no relative movement between them when the measuring tip is subject to rapid acceleration or deceleration, as in the event of the measuring tip being suddenly released and its motion being arrested by a fixed st
31、op. The pointer should be provided with a suitable damping device. The thickness of the pointer should be approximately the same as that of the scale marks. The design of the pointer and associated scale shall be such as to reduce to the lowest possible value any errors due to parallax. For instrume
32、nts having pointers which pass over the scale, the pointer tips should overlap the scale marks by one fifth to one half of the length of the shortest scale marks. 8 Scale The scale shall normally be graduated in metric units. NOTEIf required by the purchaser, the scale may be graduated in metric and
33、 imperial units, in which case the metric units shall predominate. The scale shall consist of black marks on a white ground or such other combination of contrasting colours as will show up with equal clarity so that it can be conveniently read under ordinary workshop lighting conditions. All scale m
34、arks shall have a clean sharp outline and be uniform in thickness. The recommended line thickness is 0.2 mm to 0.3 mm. Both fifth and tenth scale intervals shall be indicated by a slightly longer mark. On single range scales, at least every tenth interval shall be numbered and the value of each scal
35、e interval shall be clearly marked within the scale area or be numbered at least every tenth interval and the half scale value shall be clearly marked at the plus and minus ends of the scale. NOTEFor illustrations of the terms “scale mark” and “scale interval”, see Figure 2. On multi-range scales, a
36、t least every tenth interval shall be numbered and the value of each scale interval shall be clearly marked within the scale area using a suitable code to identify scale and scale interval values. Fine subdivision of the scale is deprecated; it is recommended that no scale interval should be less th
37、an 1 mm. The zero scale mark should preferably be at the centre of the scale. Scales requiring the zero position to be other than in the centre position should be the subject of agreement between the purchaser and the manufacturer of the instrument. The relative movement of the pointer and scale sho
38、uld be such as to suggest to the observer the direction of movement of the measuring tip as the work is passed under it. For example, when the pointer moves over a fixed scale, an increase in the size of the work should be indicated by a movement of the pointer upwards on a vertical scale or to the
39、right on a horizontal scale. If the scale is in the form of an arc above the centre of rotation of the pointer, a clockwise movement of the pointer should indicate an increase in the work size. Where the scale is in the form of an arc below the centre of rotation of the pointer, an anticlockwise mov
40、ement of the pointer should indicate an increase in work size. The scale shall be boldly marked with plus and minus signs to indicate increases and decreases in the size of the measured work. Figure 2 ScaleBS1054:1975 BSI 06-1999 3 9 Performance 9.1 Consistency of reading. The consistency of reading
41、 of the comparator shall be examined by carrying out the following series of tests; the permissible errors are stated in Table 1 and are related to the magnification factor. 9.1.1 When the instrument is set to read on a workpiece and the measuring head is gently tapped, the maximum change in reading
42、 shall not exceed one half of the appropriate amount given in Table 1. 9.1.2 When a true cylinder is passed under the measuring tip from the front, from the rear, from the LH side, from the RH side, the maximum difference in reading found shall not exceed one half of the values in Table 1. 9.1.3 The
43、 reading obtained when sliding a gauge block under the tip shall not differ from subsequent readings obtained by operating the lifting device by more than the appropriate amount given in Table 1. Table 1 Tolerances on consistency of reading 9.2 Accuracy of scale. The accuracy of the scale of the ins
44、trument shall be tested by taking readings on a suitable series of calibrated gauge blocks, first over the positive half of the scale and then over thenegative half of the scale, checking at each major division. No reading shall have an error exceeding 1 % of the reading or the appropriate amount ()
45、 given in Table 1, whichever is greater. For example, in the case of a comparator having a magnification factor of 1000, the maximum permissible error over the range 0 to 0.05 mm would be 0.000 5 and, beyond this range, 1 % of the reading. 10 Marking Each instrument shall be marked with the makers n
46、ame or recognized trademark and with a serial number. Magnification factor of measuring head Tolerance on reading mm From 250 up to and including 300 0.002 0 Above 300 up to and including 400 0.001 5 Above 400 up to and including 600 0.001 0 Above 600 up to and including 1 000 0.000 8 Above 1 000 up
47、 to and including 2 000 0.000 5 Above 2 000 up to and including 5 000 0.000 3 Above 5 000 up to and including 10 000 0.000 1 Above 10 000 0.000 05BS 1054:1975 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing Britis
48、hStandards. 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 c
49、onstant 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 Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel:02089969000. Fax:02089967400. BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions of standards. Buying standards Orders for all BSI, international and foreign standa
