1、BRITISH STANDARD CONFIRMED JULY 1986 BS 4235-1: 1972 Incorporating Amendments Nos. 1,2 and 3 Specification for Metric keys and keyways Part 1: Parallel and taper keysBS4235-1:1972 This British Standard, having been approved by the Mechanical Engineering Industry Standards Committee, was published un
2、der the authority of the Executive Board on 22 February, 1972 BSI 01-1999 First published, December, 1967 This revision, February, 1972 The following BSI reference relates to the work on this standard: Committee references MEE/4 ISBN 580 06988 5 Co-operating organizations The Mechanical Engineering
3、Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: The Government department and scientific and industrial organizations marked with an asterisk i
4、n the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: Associated Offices Technical Committee Engineering Equipment Users Association* Association of Consulting Engineers Gas Council Association of Mining Ele
5、ctrical and Institution of Civil Engineers Mechanical Engineers Institution of Gas Engineers British Chemical Plant Manufacturers Institution of Heating and Ventilating Association Engineers British Compressed Air Society Institution of Mechanical Engineers* British Electrical and Allied Manufacture
6、s Institution of Mechanical Engineers Association* (Automobile Division) British Gear Manufactures Association* Institution of Plant Engineers British Internal Combustion Engine Institution of Production Engineers* Manufacturers Association* Locomotive and Allied Manufacturers British Mechanical Eng
7、ineering Confederation Association of Great Britain* British Pump Manufactures Association London Transport Executive British Steel Industry* Machine Tool Trades Association Crown Agents for Oversea Governments and Ministry of Defence Administrations Ministry of Defence, Army Department Department o
8、f Employment (H.M. Factory National Coal Board Inspectorate) National Physical Laboratory (Department Department of the Environment of Trade and Industry) Department of Trade and Industry* Royal Institute of British Architects. Electricity Council, the Central Electricity Telecommunication Engineeri
9、ng and Generating Board and the Area Boards in Manufacturing Association England and Wales Water Tube Boilermakers Association. Association of Correspondence Colleges Milling Cutter and Reamer Association British Ship Research Association Ministry of Defence, Navy Department Cycle and Motor Associat
10、ion Society of British Aerospace Companies Gauge and Tool Makers Association Steel Works Plant Association Institution of Engineers and Shipbuilders in Taper Pin Manufacturers Association Scotland Amendments issued since publication Amd. No. Date Comments 1478 July 1974 2334 July 1978 8776 September
11、 1995 Indicated by a sideline in the marginBS 4235-1:1972 BSI 01-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Fits 1 3 Material 1 4 Dimensions and tolerances 1 Table 1 Dimensions and tolerances of keyways for square parallel keys 2 Table 2 Dimensions and
12、 tolerances of square parallel keys 4 Table 3 Dimensions and tolerances of keyways for rectangular parallel keys 5 Table 4 Dimensions and tolerances of rectangular parallel keys 7 Table 5 Dimensions and tolerances of keyways for square taper keys 9 Table 6 Dimensions and tolerances of square taper k
13、eys 11 Table 7 Dimensions and tolerances of keyways for rectangular taper keys 12 Table 8 Dimensions and tolerances of rectangular taper keys 14 Table 9 Preferred lengths of keys 16 Table 10 Tolerance of interference fit square parallel keys 17 Table 11 Tolerance of interference fit rectangular para
14、llel keys 18BS4235-1:1972 ii BSI 01-1999 Foreword In order to keep abreast of progress in the industries concerned, British Standards are subject to periodical review. Suggestions for improvements will be recorded and in due course brought to the notice of the committees charged with the revision of
15、 the standards to which they refer. A complete list of British Standards, numbering over 9 000, fully indexed and with a note of the contents of each, will be found in the BSI Catalogue which may be purchased from BSI Sales Department. The Catalogue may be consulted in many public libraries and simi
16、lar institutions. This standard makes reference to the following British Standards: BS 46, Keys and keyways and taper pins. Part 1. Keys and keyways. BS 970, Wrought steels in the form of blooms, billets, bars and forgings. Part 1. Carbon and carbon manganese steels, including free cutting steels. B
17、S 4500, ISO limits and fits. BS 4500-1, General, tolerances and deviations. This British Standard is the first of a series for metric keys and keyways and has been prepared under the authority of the Mechanical Engineering Industry Standards Committee. The essential data for this standard have been
18、extracted from ISO Recommendations R773 1)and R774 2) . Although similar in principle to BS46-1, for inch keys and keyways, it provides for three classes of fit for square and rectangular parallel keys and keyways, namely, “free”, “normal” and “close”, and the provision of these three types of fit i
19、s in accordance with ISO practice. In addition to the three classes of fit agreed byISO as mentioned above, the United Kingdom has found it necessary to introduce an additional class, an interference fit. This is considered necessary to avoid the possibility of the rotation of the key which might oc
20、cur in high torque, in reversing conditions, in applications where torsional vibration exists, or in precision applications. The marked difference in dimensions between the inch and metric keys and keyways was, in the early days of metrication, the subject of considerable discussion and, quite natur
21、ally, fears were expressed that there would be problems due to the loading on the side faces of the key and keyway for any given shaft size. These metric sections of keys have been in satisfactory use in most European countries for many years. It was, however, still desirable that there should be th
22、e satisfaction of more positive assurance that no design limitation exists in the application of the thinner metric key sections. At the request of technical committee MEE/4, the National Engineering Laboratory explored some of the questions which had been raised. The results of these investigations
23、 have been published and they demonstrate the effects of both static and dynamic tests, and include comparisons of the stresses and deformations of the two key forms at very high loadings. For the benefit of designers who are concerned with high static or dynamic torque loadings in keyed shafting sy
24、stems, the reports are: 1) ISO Recommendation R 773, “Rectangular or square parallel keys and their corresponding keyways (dimensions in millimetres)”. 2) ISO Recommendation R 774, “Taper keys and their corresponding keyways (with or without gib head) (dimensions in millimetres)”. NEL Report No. 489
25、 “Static torsion tests on shrink-fit and keyed components” by D M Macdonald NEL Report No. 526 “A comparison of inch and metric keys in static torsion” by D M MacdonaldBS4235-1:1972 BSI 01-1999 iii NOTEThe titles of the British Standards referred to in this standard are listed on page2. The above re
26、ports are obtainable from the Reports Unit, National Engineering Laboratory, East Kilbride, Glasgow, to which enquirers should apply direct. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct applica
27、tion. Compliance with a British Standard does not of itself confer immunity from legal obligations. NEL Report No. 606 “Loaded key reaction and stresses” by D M Macdonald NEL Report No. 635 “Key length and its effect on the static torsional strength of a keyed joint” by D M Macdonald Summary of page
28、s This document comprises a front cover, an inside front cover, pages i to iv, pages1to 18 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.iv blankBS4235-1:1972 BSI
29、01-1999 1 1 Scope This British Standard relates to the following types of keys and keyways with dimensions in millimetres: 1) square parallel, 2) rectangular parallel, 3) square taper, gib-head and plain, 4) rectangular taper, gib-head and plain. In addition, a fourth class of fit is provided in thi
30、s British Standard to give an interference fit. Three classes of fit are provided for the square and rectangular parallel keys and keyways, namely “free”, “normal” and “close”, and the dimensions and tolerances specified are in accordance with ISO Recommendations R773 3) and R774 4) . 2 Fits The thr
31、ee classes of fit dealt with in this standard are intended to meet varying requirements as follows: 1) Free, where the hub is required to slide over the key when in use. 2) Normal, where the key is to be inserted in the keyway with minimum fitting, as is required for mass production assembly. 3) Clo
32、se, where an accurate fit of key is required. In this class, fitting will be required under maximum material conditions, and if it is required to obtain these conditions some selection of components may be necessary. 4) Interference, where a fit is required such that there is no possibility of play
33、between the key and keyway in the shaft and hub. In this class of fit, hand fitting will be necessary. NOTEThis class of fit is described in ISORecommendationsR773, “Rectangular or square parallel keys and their corresponding keyways (dimensions in millimetres)”, and R774, “Taper keys and their corr
34、esponding keyways (with or without gib head) (dimensions in millimetres)”, as “fitted”. 3 Material Unless otherwise specified, keys complying with the requirements of this British Standard shall be manufactured from steel complying with BS970 having a tensile strength of not less than550MN/m 2in the
35、 finished condition. Keybar to the tolerances on width (b)and thickness (h) specified for the finished keys will not necessarily be commercially available. NOTEThe following steels specified in BS970-1, will meet the above requirement to the maximum sizes indicated: 4 Dimensions and tolerances 4.1 T
36、he dimensions and tolerances of metric keys and keyways shall be as given in Table 1 to Table 8. The dimensions and tolerances of interference fit keys shall be given in Table 10 and Table 11. Recommended standard lengths are given in Table 9. 4.2 The standard does not deal with misalignment or offs
37、et greater than can be accommodated within the dimensional tolerances. In heavily stressed applications, a check should be made to ensure that the cumulative effect of misalignment and/or offset does not prevent a good bearing on the key. 4.3 Keys, as supplied, are not normally chamfered or radiused
38、 but these operations may be carried out during manufacture by agreement between the purchaser and the manufacturer. 4.4 Taper keys fitted in a keyway with tolerance P9, providing there is no excessive side interference, will be regarded as complying with the requirements of this British Standard. 3
39、) ISO Recommendation R 773, “Rectangular or square parallel keys and their corresponding keyways (dimensions in millimetres)”. 4) ISO Recommendation R 774, “Taper keys and their corresponding keyways (with or without gib head) (dimensions in millimetres)”. mm 070M20 25 14 070M26 36 20 080M30 90 45 0
40、80M40 100 50BS 4235-1:1972 2 BSI 01-1999 Table 1 Dimensions and tolerances of keyways for square parallel keys BS 4235-1:1972 BSI 01-1999 3 Table 1 Dimensions and tolerances of keyways for square parallel keys All dimensions in millimetres 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Shaft Key (see Note) Key
41、way nominal diameter (seeNote) d width b depth radius r section b h width thickness tolerance for class of fit shaft t 1 hub t 2 free normal close and interference over incl. nom. shaft (H9) hub (D10) shaft (N9) hub (J s 9) a shaft and hub (P9) nom. tol. nom. tol. max. min. 6 8 8 10 2 2 3 3 2 3 1.2
42、1.8 1 1.4 0.16 0.16 0.08 0.08 10 12 4 4 4 2.5 1.8 0.16 0.08 12 17 5 5 5 3 2.3 0.25 0.16 17 22 6 6 6 3.5 2.8 0.25 0.16 NOTEThe relations between shaft diameter and key section given above are for general applications. The use of smaller key sections is permitted if suitable for the torque transmitted
43、. In cases such as stepped shafts when larger diameters are required, for example to resist bending, and when fans, gears and impellers are fitted with a smaller key than normal, an unequal disposition of key in shaft with relation to the hub results. Therefore, dimensions d t 1and d + t 2should be
44、recalculated to maintain the h/2 relationship. The use of larger key sections which are special to any particular application is outside the scope of this standard. a The limits for tolerance J s 9 are quoted from BS 4500, “ISO limits and fits”, to three significant figures. + 0.025 0 + 0.060 + 0.02
45、00.004 0.029 + 0.0120.012 0.006 0.031 + 0.1 0 + 0.1 0 + 0.030 0 + 0.078 + 0.030 00.030 + 0.0150.015 0.012 0.042 BS 4235-1:1972 4 BSI 01-1999 Table 2 Dimensions and tolerances of square parallel keys All dimensions in millimetres 1 2 3 4 5 6 7 8 Width b Thickness h Chamfer s Range of lengths l a nom.
46、 tol. (h9) nom. tol. (h9) min. max. from incl. 2 2 0.16 0.25 6 20 3 3 0.16 0.25 6 36 4 4 0.16 0.25 8 45 5 5 0.25 0.40 10 56 6 6 0.25 0.40 14 70 a See Table 9 for preferred lengths of keys. 00.025 00.025 00.030 00.030 BS 4235-1:1972 BSI 01-1999 5 Table 3 Dimensions and tolerances of keyways for recta
47、ngular parallel keysBS 4235-1:1972 6 BSI 01-1999 Table 3 Dimensions and tolerances of keyways for rectangular parallel keys All dimensions in millimetres 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Shaft Key (seeNote) Keyway nominal diameter (seeNote) d section b h width thickness width b depth tolerance fo
48、r class of fit radius r free normal close and interference shaft t 1 hub t 2 over incl. nom. shaft (H9) hub (D10) shaft (N9) hub (J s 9)* shaft and hub(P9) nom. tol. nom. tol. max. min. 22 30 30 38 8 7 10 8 8 10 4 5 3.3 3.3 0.25 0.40 0.16 0.25 38 44 12 8 12 5 3.3 0.40 0.25 44 50 50 58 14 9 16 10 14
49、16 5.5 6 3.8 4.3 0.40 0.40 0.25 0.25 58 65 18 11 18 7 4.4 0.40 0.25 65 75 20 12 20 7.5 4.9 0.60 0.40 75 85 85 95 22 14 25 14 22 25 9 9 5.4 5.4 0.60 0.60 0.40 0.40 95 110 28 16 28 10 6.4 0.60 0.40 110 130 32 18 32 11 7.4 0.60 0.40 130 150 36 20 36 12 8.4 1.00 0.70 150 170 40 22 40 13 9.4 1.00 0.70 170 200 45 25 45 15 10.4 1.00 0.70 200 230 50 28 50 17 11.4 1.00 0.70 230 260 56 32 56 20 12.4 1.60 1.20 260 290 290 330 63 32 70 36 63 70 20 22 12.4 14.
