1、BRITISH STANDARD BS 7675:1993 ISO 6524:1992 Plain bearings Thin-walled half bearings Checking of peripheral length UDC 621.822.5:531.7BS7675:1993 This British Standard, having been prepared under the directionof the Machinery and Components Standards Policy Committee, was published underthe authorit
2、y of the Standards Board and comes intoeffect on 15July1993 BSI 04-2000 The following BSI references relate to the work on this standard: Committee reference MCE/12 Draft for comment 89/78345 DC ISBN 0 580 22196 2 Committees responsible for this British Standard The preparation of this British Stand
3、ard was entrusted by the Machinery and Components Standards Policy Committee (MCE/-) to Technical Committee MCE/12, upon which the following bodies were represented: Association of Bronze and Brass Founders British Plastics Federation British Powder Metal Federation Copper Development Association In
4、stitution of Diesel and Gas Turbine Engineers Institution of Mechanical Engineers Society of Motor Manufacturers and Traders Ltd. Amendments issued since publication Amd. No. Date CommentsBS7675:1993 BSI 04-2000 i Contents Page Committees responsible Inside front cover National foreword iii 1 Scope
5、1 2 Normative references 1 3 Definitions 1 4 Symbols 2 5 Purpose of checking 2 6 Checking methods 2 7 Choice and designation of checking method 4 8 Measuring equipment 4 9 Measuring equipment requirements 4 10 Gauging tools for establishing the datum 6 11 Checking block requirements 6 12 Master shel
6、l and comparison shell requirements 10 13 Correction factors 12 14 Typical checking procedure 13 15 Condition of the half-bearings to be checked 13 16 Measuring errors 13 17 Accuracy of methods used 14 18 Specifications on bearing drawings 14 19 Specifications for the control of the checking means 1
7、4 Annex A (normative) Determination of the correction factor of the master checking block Method A 16 Annex B (normative) Determination of the correction factor of the master checking block Method B 20 Annex C (normative) Determination of the correction factor of the series checking block used alone
8、 24 Annex D (normative) Determination of the correction factor of the master shell or comparison shell 24 Annex E (normative) Tests and calculation of repeatability, reproducibility and comparability 25 Figure 1 Nip, a 1 Figure 2 Principle of method A 3 Figure 3 Principle of method B 3 Figure 4 Typi
9、cal measuring equipment with one column, for method A 5 Figure 5 Typical measuring equipment with two columns, for method B 6 Figure 6 Checking block 7 Figure 7 Master shell 11 Figure 8 Stepped master shell not suitable for checking bearings of uniform wall thickness 11 Figure A.1 17 Figure A.2 17 F
10、igure A.3 18 Figure A.4 18 Figure B.1 21 Figure B.2 21 Figure B.3 22BS7675:1993 ii BSI 04-2000 Page Table 1 4 Table 2 4 Table 3 4 Table 4 8 Table 5 9 Table 6 9 Table 7 9 Table 8 10 Table 9 10 Table 10 10 Table 11 11 Table 12 12 Table 13 12 Table 14 14 Table 15 15 List of references Inside back cover
11、BS7675:1993 BSI 04-2000 iii National foreword This British Standard has been prepared under the direction of the Machinery and Components Standards Policy Committee. It is identical with ISO 6524:1992 Plain bearings Thin-walled half bearings Checking of peripheral length, published by the Internatio
12、nal Organization for Standardization (ISO). Textual error. When adopting the text of the International Standard, the textual error given below was discovered. It has been marked in the text and has been reported to ISO/TC 123/SC3 in a proposal to amend the text of the International Standard. On page
13、 2, in clause 4, Youngs modulus is in newtons per square millimetre. 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 immun
14、ity from legal obligations. Cross-references International Standard Corresponding British Standard BS 4480 Plain bearings: metric series ISO 3548:1978 Part 5:1979 Dimensions, tolerances and methods of checking thin-walled half bearings (Identical) BS 4480 Plain bearings: metric series ISO 6864:1984
15、Part 8:1984 Specification for dimensions, tolerances and methods of checking of thin-walled flanged half bearings (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages1 to 26, an inside back cover and a back cover. This standard has been upda
16、ted (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankBS7675:1993 BSI 04-2000 1 1 Scope This International Standard specifies methods of checking the measuring equipment and gauging tools necessary for measu
17、ring the peripheral length (or nip or crush) of thin-walled half-bearings. Thin-walled half-bearings are flexible and, in the free condition, do not conform to a cylindrical profile. This is one reason why the peripheral length of the half-bearings can only be measured under a constraining load by u
18、se of specialized measuring equipment. Measuring equipment different from that illustrated in this International Standard can be used, providing the measuring accuracy of the equipment is consistent with the specifications given in clause 17. This International Standard does not include measurement
19、of the joint face taper. It applies to thin-walled half-bearings, the specifications of which are given in ISO3548and ISO6864. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of
20、 publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain
21、registers of currently valid International Standards. ISO 3548:1978, Plain bearings Thin-walled half bearings Dimensions, tolerances and methods of checking. ISO 6864:1984, Plain bearings Thin-walled flanged half bearings Dimensions, tolerances and methods of checking. 3 Definitions For the purposes
22、 of this International Standard, the following definitions apply. 3.1 peripheral length the circumferential length which runs from one joint face to the other 3.2 nip; crush the value, a, by which a half-bearing fitted in a checking block of bore diameter d cbunder a predetermined checking load F ex
23、ceeds the defined peripheral length of the checking block bore (see Figure 1) NOTE 1In practice, the datum serves as a basis for measuringa (see Figure 2). 3.3 repeatability the closeness of agreement between successive results obtained with the same method on the same test piece, under the same con
24、ditions (same operator, same measuring equipment, same checking place and time intervals) NOTE 2Repeatability is assessed from the standard deviation of repeatability % . See Annex E. 3.4 reproducibility the closeness of agreement between individual results obtained with the same method on the same
25、test piece but under different conditions (identical or different operator, measuring equipment, checking place and times) NOTE 3For the purposes of this International Standard, reproducibility is the difference between the two averages obtained from two sets of measuring equipment. See Annex E. 3.5
26、 comparability the accuracy in the case of operators working in different checking places at different periods and each of them achieving individual results, one using method A and the other method B, on the same half-bearing in different checking blocks NOTE 4Comparability is assessed from the diff
27、erence between the two averages obtained from the two methods. See Annex E. Figure 1 Nip, aBS7675:1993 2 BSI 04-2000 4 Symbols NOTE 5The characteristic subscripts are as follows: bs: bearing to be checked cb: checking block cbm: master checking block cbs: series checking block cs: comparison shell M
28、: measured ms: master shell th: theoretical 5 Purpose of checking It is necessary to keep to within the nip tolerances of ISO3548and ISO6864in order to guarantee the designated mounting compression (interference fit) for the half-bearings in the housing bore. 6 Checking methods 6.1 Method A The chec
29、king load, F, is directly applied via the measuring head with a pivoting toe piece to one joint face of the half-bearing whilst the other joint face is in contact with a fixed stop (see Figure 2). 6.2 Method B The checking loads F 1and F 2are applied via the measuring head and two toe pieces to both
30、 joint faces of the half-bearing (see Figure 3). NOTE 6In the case of method A, the fixed stop exerts the required counter-force which, in the case of method B, is applied directly by the measuring equipment via two toe pieces. EXAMPLE a or a 1+ a 2 nip, in millimetres B width of the half-bearing wi
31、thout flange, in millimetres B 1 checking block width (construction for flanged half-bearings), in millimetres B 2 checking block width, in millimetres B 3 checking block width (construction for half-bearings without flange), in millimetres B ms master shell width, in millimetres d cb diameter of th
32、e checking block bore, in millimetres a D bs outside diameter of the half-bearing to be checked, in millimetres D ms outside diameter of the master shell, in millimetres a E Youngs modulus, in newtons per square metre b f coefficient of friction in calculation of deflection under load F = F 1= F 2 c
33、hecking load, in newtons F cor correction factor, in millimetres a h fillet radius between back and flange on flanged half-bearing, in millimetres H cb distance from the bottom of the checking block bore to the datum plane, in millimetres a %H cb elastic deformation of the height of the checking blo
34、ck under load, in millimetres K 1 checking block chamfer (construction for half-bearings without flange), in millimetres K 2 checking block chamfer (construction for flanged half-bearings), in millimetres l peripheral length, in millimetres a %l deviation of the actual peripheral length of the check
35、ing block, in millimetres p E elastic depression of the toe piece, in millimetres R a surface roughness, in microns s cs wall thickness of the comparison shell, in millimetres s ms wall thickness of the master shell, in millimetres s tot total wall thickness of the half-bearing, in millimetres u unc
36、ertainty of measurement w width of the toe piece contact area, in millimetres z distance between flanges of the flanged half-bearing, in millimetres empirical correction to compensate for the difference in elastic deflections under load between method A and method B, in millimetres correction estima
37、ted by calculation standard deviation a The symbol may be followed by a subscript defining the gauging tool to which the symbol is applied and/or by a subscript indicating an effective measured value or a theoretical value. b See national foreword for details of textual error. Method A F = 6 000 N M
38、ethod B F 1= 6000 N F 1= 6 000 N BS7675:1993 BSI 04-2000 3 Figure 2 Principle of method A Figure 3 Principle of method BBS7675:1993 4 BSI 04-2000 7 Choice and designation of checking method 7.1 Choice of checking method Recommendations for choosing either method A or method B, based on the dimension
39、s of the half-bearings to be checked, are given in Table 1. However, any size of bearing may be tested by either method by agreement between the manufacturer and user. In that case, a correction should be applied to compensate for the difference in deflections at joint face(s) under load between met
40、hod A and method B, and be such that a A= a B1+ a B2+ The value of shall be determined empirically by actual measurements obtained on the two different types of equipment used. Since the detailed design of the checking feature will vary between different manufacturers, the value of established by on
41、e manufacturer cannot be transferred to another, who shall determine it separately. See example in Annex E. For general guidance, the value of may be derived from the formula used in the mathematical analysis of belt friction, which gives With a value of the friction coefficient f = 0,15, the formul
42、a becomes (See also 16.5.) Table 1 7.2 Designation of checking method Example of the designation of method B for checking thin-walled half-bearings with an outside diameter, D bs , of340mm: Method ISO 6524-B-340 8 Measuring equipment Figure 4 and Figure 5 show typical measuring equipment for measuri
43、ng the nip (crush) by methodA and by method B, respectively. NOTE 7Figure 4 and Figure 5 show hydraulically operated equipment. Pneumatically or mechanically operated equipment may also be used. 9 Measuring equipment requirements The most important factors affecting the accuracy of the measuring equ
44、ipment (and hence the measured nip value) are given below. 9.1 Tolerance on checking load setting The permissible tolerances are given in Table 2. Table 2 9.2 Speed of approach of measuring head The checking load, F, shall be applied to the joint face(s) of the half-bearing so that shock load will n
45、ot occur. The speed of approach shall be10mm/s 2mm/s. For devices in which the speed of approach cannot be altered, the load shall be applied, released and applied a second time before the measurement is made. 9.3 Construction of measuring head The measuring head shall be so constructed that it is a
46、ccurately guided and moves normal to the datum of the checking block. The deviation from parallelism between the toe piece(s) in the measuring head and the supporting plane of the checking block shall not exceed0,04mm per100mm in a radial direction. 9.4 Accuracy of the measuring plane of the toe pie
47、ces Specifications on the accuracy of the measuring plane of the toe pieces are given in Table 3. Table 3 9.5 Accuracy of the dial gauge Uncertainty of measurement u u 1,24m ( 2B) with B = 0,3 4m D bs mm Recommended checking method D bsu 200 A, B 200 D bsu 500 B F Tolerance on F N % F u 2 000 1,25 2
48、 000 F u 5 000 1 5 000 F u 10 000 0,75 10 000 F u 50 000 0,5 50 000 F 0,25 Dimensions and tolerances in millimetres Surface roughness in microns D bs Surface roughness R a Tolerance on flatness D bsu 160 0,2 0,001 5 160 D bsu 340 0,4 0,003 340 D bsu 500 0,004BS7675:1993 BSI 04-2000 5 Figure 4 Typica
49、l measuring equipment with one column, for method ABS7675:1993 6 BSI 04-2000 10 Gauging tools for establishing the datum The following equipment can be used for carrying out measurements: a master checking block (for reference measurements) (see clause 11), a series checking block (for series control in production) (see clause 11), or a master shell or comparison shell (for series control in production) (see clause 12). It can be used in three ways (as indicated in 10.1, 10.2 and 10.3) to
