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1、BRITISH STANDARD BS 7751-1: 1994 Incorporating Amendment No. 1 Prevailing torque type wire thread inserts Part 1: Specification for ISO metric coarse pitch threads ICS 21.040.10 BS 7751-1:1994 This British Standard, having been prepared under the direction of the General Mechanical Engineering Stand
2、ards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 September 1994 BSI 2006 The following BSI references relate to the work on this standard: Committee reference GME/9 Draft for comment 92/84542 DC ISBN 0 580 23311 1 Committees responsible for
3、this British Standard The preparation of this British Standard was entrusted by the General Mechanical Engineering Standards Policy Committee (GME/-) to Technical Committee GME/9, upon which the following bodies were represented: BEAMA Ltd. British Constructional Steelwork Association Ltd. British I
4、ndustrial Fasteners Federation British Steel Industry British Steel Industry (Wire Section) Gauge and Tool Makers Association Society of Motor Manufacturers and Traders Ltd. Washer Manufacturers Association of Great Britain The following bodies were also represented in the drafting of the standard,
5、through subcommittees and panels: Defence Manufacturers Association General Municipal Boilermaker and Allied Trades Union Screw Thread Tool Manufacturers Association Society of British Aerospace Companies Limited Amendments issued since publication Amd. No.DateComments 1665331 October 2006Changed va
6、lues in Tables 2 and 3 BS 7751-1:1994 BSI 2006i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2References1 3Definitions1 4Dimensions1 5Material8 6Finish8 7Insert selection8 8Installation9 9Marking10 Annex A (informative) Insert selection12 Figure 1 Insert wire profile in
7、finished coiled state3 Figure 2 Dimensions of insert in free (unfitted) state7 Figure 3 Position of locking element in fitted insert8 Figure 4 Insert in fitted state11 Table 1 Dimensions of insert wire profile in finished coiled state2 Table 2 Dimensions of insert in free (unfitted) state4 Table 3 P
8、osition of locking element in fitted insert8 Table 4 Insert fitted length9 Table A.1 Recommended nominal lengths of insert to be inserted into a material of a given shear strength that can be used with a bolt of a certain property class12 List of referencesInside back cover BS 7751-1:1994 ii BSI 200
9、6 Foreword This Part of BS 7751 has been prepared under the direction of the General Mechanical Engineering Standards Policy Committee. It is a Part of a series for prevailing torque wire thread inserts. BS 7751-2 provides a specification for ISO metric fine pitch threads. This publication does not
10、purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 t
11、o 12, an inside back cover 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. BS 7751-1:1994 BSI 20061 1 Scope This Part of BS 7751 specifies requirements for prevail
12、ing torque wire thread inserts which, when fitted into an appropriately prepared hole, will: a) provide ISO metric coarse pitch female threads of tolerance class 5H or 6H in the free running coils with sizes from M2.2 to M39 inclusive; b) accept ISO metric male threads conforming to BS 3643-1:1981 a
13、nd BS 3643-2:1981; c) give a frictional resistance to rotation of a male threaded component assembled with it, of such a value that the insert assembly is considered self locking; d) operate successfully in the temperature range 50 C to + 300 C. NOTE ISO metric MJ threads conforming to BS 6293-1 and
14、 BS 6293-2 may be used with these inserts. 2 References 2.1 Normative references This Part of BS 7751 incorporates, by dated or undated reference, provisions from other publications. These normative references are made at the appropriate places in the text and the cited publications are listed on th
15、e inside back cover. For dated references, only the edition cited applies; any subsequent amendments to or revisions of the cited publication apply to this Part of BS 7751 only when incorporated in the reference by amendment or revision. For undated references, the latest edition of the cited public
16、ation applies, together with any amendments. 2.2 Informative references This Part of BS 7751 refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be ma
17、de to the latest editions. 3 Definitions For the purposes of this Part of BS 7751, the following definitions apply. 3.1 prevailing torque type wire thread insert a wire thread insert which, when installed in a hole tapped in accordance with BS 4377:1991, will provide a female thread containing a pre
18、vailing torque element. The frictional resistance of the prevailing torque element is of such a value that the insert is considered screw locking 3.2 prevailing torque element (locking device) the coil(s) of the insert designed to impose friction between the insert and the installed male thread 3.3
19、prevailing (locking) torque the torque to be applied to maintain rotation of the male part relative to the installed insert when the assembly is under no axial load and the thread of the male part is fully engaged with the locking element NOTE There is no permanence of prevailing torque for indefini
20、te reusability. The reusability should be determined by the application. 4 Dimensions 4.1 Insert wire profile The dimensions of the insert wire profile when it is in the finished coiled state shall be in accordance with Table 1 and Figure 1. 4.2 Unfitted insert The dimensions of an unfitted insert s
21、hall be in accordance with Table 2 and Figure 2. The surface roughness of the insert wire in the finished coiled state shall not exceed 8 m. NOTE 1 Minimum contact pressure is to be used when measuring the insert outside diameter to avoid distortion of the insert. NOTE 2 Ignore any reduced leading c
22、oil if it is present when measuring the insert outside diameter. NOTE 3 Since the relationship between the insert unfitted length and the number of coils is interdependent with coiling tension, the number of coils N is given for identification purposes only. NOTE 4 The notch depth is to be sufficien
23、t to allow the tang to be broken off cleanly with a sharp blow after installation and then permit the through passage of a male threaded component. 4.3 Locking coils (prevailing torque element) The coils which form the locking element shall be contained within the limits specified in Table 3 and Fig
24、ure 3. NOTE The number, shape and orientation of the locking coils, the spacing between the locking coils and the number of faces on the locking coils are the sole responsibility of the manufacturer. 4 BS 7751-1:1994 2 BSI 2006 Table 1 Dimensions of insert wire profile in finished coiled state Dimen
25、sions in millimetres Thread sizeXWTE diameterpitchmin.max.min.max.min.max.min.max. M2.2 M2.5 M3 M3.5 M4 M4.5 M5 M6 M7 M8 M10 M12 M14 M16 M18 M20 M22 M24 M27 M30 M33 M36 M39 0.45 0.45 0.5 0.6 0.7 0.75 0.8 1 1 1.25 1.5 1.75 2 2 2.5 2.5 2.5 3 3 3.5 3.5 4 4 0.333 0.333 0.368 0.445 0.521 0.559 0.597 0.74
26、4 0.744 0.935 1.125 1.311 1.501 1.501 1.880 1.880 1.880 2.258 2.258 2.634 2.634 3.012 3.012 0.340 0.340 0.378 0.455 0.531 0.569 0.607 0.757 0.757 0.947 1.138 1.326 1.516 1.516 1.895 1.895 1.895 2.273 2.273 2.652 2.652 3.030 3.030 0.445 0.445 0.490 0.594 0.691 0.737 0.785 0.986 0.986 1.242 1.501 1.76
27、0 2.002 2.002 2.497 2.497 2.497 3.028 3.028 3.528 3.528 4.056 4.056 0.488 0.488 0.541 0.650 0.757 0.813 0.866 1.082 1.082 1.354 1.623 1.895 2.164 2.164 2.705 2.705 2.705 3.249 3.249 3.790 3.790 4.331 4.331 0.323 0.323 0.358 0.432 0.503 0.538 0.574 0,716 0,716 0,897 1,077 1,255 1.435 1.435 1.793 1.79
28、3 1.793 2.151 2.151 2.512 2.512 2.870 2.870 0.394 0.394 0.437 0.526 0.612 0.655 0.701 0.874 0.874 1.095 1.313 1.532 1.750 1.750 2.187 2.187 2.187 2.624 2.624 3.063 3.063 3.500 3.500 0.274 0.274 0.307 0.368 0.434 0.467 0.500 0.625 0.625 0.787 0.950 1.105 1.267 1.267 1.590 1.590 1.590 1.915 1.915 2.23
29、8 2.238 2.563 2.563 0.292 0.292 0.325 0.389 0.455 0.488 0.521 0.650 0.650 0.813 0.975 1.135 1.298 1.298 1.623 1.623 1.623 1.948 1.948 2.273 2.273 2.598 2.598 BS 7751-1:1994 BSI 20063 NOTE See Table 1 for dimensions. Figure 1 Insert wire profile in finished coiled state BS 7751-1:1994 4 BSI 2006 Tabl
30、e 2 Dimensions of insert in free (unfitted) state Dimensions in millimetres Thread sizeOutside diameter D Nominal lengthNo. of coils N Tang length L Space for tang M diameter, dPitchmin.max.min.max.min.max. 1d2.93.4 1.5d5.15.6 M2.20.452.83.02d7.4 7.91.400.98 2.5d9.610.1 3d11.912.4 1d3.13.6 1.5d5.56.
31、0 M2.50.453.203.702d7.88.41.600.98 2.5d10.210.8 3d12.513.0 1d3.54.0 1.5d6.16.6 M30.53.804.352d8.69.11.901.08 2.5d11.111.6 3d13.514.1 1d3.54.0 1.5d6.16.6 M3.50.64.394.952d8.59.02.201.30 2.5d11.111.6 3d13.314.0 1d3.33.9 1.5d5.86.4 M40.75.055.602d8.38.92.501.50 2.5d11.011.6 3d13.313.9 1d3.74.3 1.5d6.46
32、.9 M4.50.755.526.072d9.39.92.621.63 2.5d11.512.3 3d14.415.0 1d3.94.4 1.5d6.67.1 M50.86.256.802d9.39.93.121.73 2.5d12.112.6 3d14.815.4 BS 7751-1:1994 BSI 20065 Dimensions in millimetres Thread sizeOutside diameter D Nominal lengthNo. of coils N Tang length L Space for tang M diameter, dPitchmin.max.m
33、in.max.min.max. 1d3.84.3 1.5d6.57.0 M6117.4017.952d9.29.83.702.20 2.5d11.812.4 3d14.615.2 1d4.65.3 1.5d7.78.3 M7118.6519.202d10.811.44.322.20 2.5d13.614.4 3d17.017.5 1d4.24.8 1.5d7.27.7 M81.2519.8010.352d10.010.54.902.70 2.5d13.013.5 3d15.816.4 1d4.65.1 1.5d7.78.3 M101.511.9412.502d10.811.45.973.27
34、2.5d14.014.5 3d17.117.6 1d4.75.2 1.5d8.09.0 M121.7514.3015.002d11.211.77.153.74 2.5d14.414.9 3d17.618.1 1d4.85.4 1.5d8.28.7 M14216.6517.72d11.512.08.324.33 2.5d14.615.2 3d18.118.6 1d5.86.3 1.5d9.410.0 M16218.9019.92d13.213.79.454.33 2.5d16.817.5 3d20.721.4 Table 2 Dimensions of insert in free (unfit
35、ted) state (continued) BS 7751-1:1994 6 BSI 2006 Dimensions in millimetres Thread sizeOutside diameter D Nominal lengthNo. of coils N Tang length L Space for tang M diameter, dPitchmin.max.min.max.min.max. 1d5.15.6 1.5d8.69.1 M182.521.3022.002d12.012.510.655.41 2.5d15.315.9 3d18.719.2 1d5.86.4 1.5d9
36、.610.1 M202.523.5524.402d13.313.911.85.41 2.5d17.117.7 3d20.821.5 1d6.57.0 1.5d10.611.1 M222.525.9026.902d14.615.112.955.41 2.5d18.719.6 3d22.823.8 1d5.86.4 1.5d9.710.2 M24328.029.12d13.514.014.06.50 2.5d17.217.7 3d21.121.6 1d6.77.2 1.5d11.011.5 M27331.4032.702d15.215.715.706.50 2.5d19.520.0 3d23.72
37、4.2 1d6.36.9 1.5d10.211.0 M303.535.1036.302d14.215.117.507.60 2.5d18.219.0 3d22.223.3 1d7.68.1 1.5d12.312.8 M333.538.1539.402d15.716.819.07.60 2.5d20.121.3 3d24.525.8 Table 2 Dimensions of insert in free (unfitted) state (continued) BS 7751-1:1994 BSI 20067 Dimensions in millimetres Thread sizeOutsi
38、de diameter D Nominal lengthNo. of coils N Tang length L Space for tang M diameter, dPitchmin.max.min.max.min.max. 1d6.67.3 1.5d10.811.6 M36441.8543.252d14.915.920.908.66 2.5d19.120.3 3d23.224.6 1d7.78.1 1.5d11.812.7 M39444.9046.402d16.417.422.458.66 2.5d20.922.1 3d25.426.7 1) See note 4 to 4.2. 2)
39、See note 3 to 4.2. Figure 2 Dimensions of insert in free (unfitted) state Table 2 Dimensions of insert in free (unfitted) state (continued) BS 7751-1:1994 8 BSI 2006 Table 3 Position of locking element in fitted insert Dimensions in millimetres Thread sizeNominal thread length 1d1.5d2d2.5d3d diamete
40、r, dpitchABABABABAB min.max.min.max.min.max.min.max.min.max. M2.20.450.41.41.02.01.52.51.53.11.53.6 M2.50.450.61.61.22.21.82.81.83.51.84.1 M30.50.71.61.52.42.23.12.23.92.24.6 M3.50.60.82.21.73.12.63.92.64.82.65.7 M40.70.92.51.93.52.94.52.95.52.96.5 M4.50.751.12.82.23.93.45.13.46.23.47.3 M50.81.33.12
41、.54.33.85.64.96.86.28.1 M611.53.73.05.24.56.74.58.24.59.7 M712.04.23.76.05.57.75.59.55.511.2 M81.252.14.94.16.96.18.96.110.96.112.9 M101.52.76.15.28.67.711.17.713.67.716.1 M121.753.47.36.410.39.413.39.416.39.419.3 M1424.08.57.512.011.015.511.019.011.022.5 M1625.09.59.013.513.017.513.021.513.025.5 M1
42、82.55.210.99.715.414.219.914.224.414.228.9 M202.56.211.911.216.916.221.916.226.916.231.9 M222.57.212.912.718.418.223.918.229.418.234.9 M2437.514.213.520.219.526.219.532.219.538.2 M2739.015.715.722.522.529.222.536.022.542.7 M303.59.717.617.225.124.732.624.740.124.747.6 M333.511.219.119.527.427.735.62
43、7.743.927.752.1 M36412.021.021.030.030.039.030.048.030.057.0 M39413.522.523.232.233.042.033.051.733.061.5 Figure 3 Position of locking element in fitted insert 5 Material The insert wire shall be manufactured from austenitic stainless steel of the type characterized as 18 % chromium, 8 % nickel. NOT
44、E The precise composition is at the manufacturers discretion. 6 Finish The finished coiled insert shall be in the natural condition. 7 Insert selection The length of insert selected shall be such that no stripping of the tapped hole in the parent metal into which the insert is fitted occurs before t
45、ensile failure of the male threaded part that is screwed into the fitted insert. NOTE Annex A gives guidance on the selection of insert length required for different grades of bolt and tapped parent material strengths. BS 7751-1:1994 BSI 20069 8 Installation The insert shall be capable of being inst
46、alled into threaded holes prepared in accordance with BS 4377:1991. NOTE 1 The class of fit produced by the installed insert, e.g. 5 H or 6 H is dependent upon the class of fit of the threaded hole into which it is installed as well as the dimensional accuracy of the insert. The users attention is t
47、herefore drawn to the importance of maintaining the tolerance requirements of BS 4377:1991. The insert fitted length shall be as given in Table 4 and Figure 4. NOTE 2 It is recommended that the insert is fitted at least a distance equal to half of its thread pitch below the surface (see Figure 4). T
48、able 4 Insert fitted length Table 4 Insert fitted length Dimensions in millimetres Thread sizeNominal lengthFitted length diameter, dpitchmin.max. 1d1.751.97 1.5d2.853.07 M2.20.452d3.954.17 2.5d5.055.27 3d6.156.37 1d2.052.27 1.5d3.303.52 M2.50.452d4.554.77 2.5d5.806.02 3d7.057.27 1d2.502.75 1.5d4.00
49、4.25 M30.52d5.505.75 2.5d7.007.25 3d8.508.75 1d2.903.20 1.5d4.654.95 M3.50.62d6.406.70 2.5d8.158.45 3d9.9010.20 Dimensions in millimetres Thread sizeNominal lengthFitted length diameter, dpitchmin.max. 1d3.303.65 1.5d5.305.65 M40.72d7.307.65 2.5d9.309.65 3d11.3011.65 1d3.754.12 1.5d6.006.37 M4.50.752d8.258.62 2.5d10.5010.87 3d12.7513.12 1d4.204.60 1.5d6.707.10 M50.82d9.209.60 2.5d11.7012.10 3d14.2014.60 1d5.005.50 1.5d8.008.50 M612d11.0011.50 2.5d14.0014.50 3d17.0017.50 1d6.006.50 1.5d9.5010.00 M712d13.0013.50
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