1、BRITISH STANDARDBS 7751-1: 1994Incorporating Amendment No. 1Prevailing torque type wire thread inserts Part 1: Specification for ISO metric ICS 21.040.10coarse pitch threadsitish Industrial Fasteners Federationitish Steel Industryitish Steel Industry (Wire Section)BS 7751-1:1994Committees responsibl
2、e for this British StandardThMechaCoBEAMABrBrBrBrGaThis British Standard, having been prepared under the direction of the General Mechanical Engineering Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 September 1994 BSI 2006The followi
3、ng BSI references relate to the work on this standard:Committee reference GME/9Draft for comment 92/84542 DCISBN 0 580 23311 1uge and Tool Makers AssociationSociety of Motor Manufacturers and Traders Ltd.Washer Manufacturers Association of Great BritainThe following bodies were also represented in t
4、he drafting of the standard, through subcommittees and panels:Defence Manufacturers AssociationGeneral Municipal Boilermaker and Allied Trades UnionScrew Thread Tool Manufacturers AssociationSociety of British Aerospace Companies LimitedAmendments issued since publicationAmd. No. Date Comments16653
5、31 October 2006 Changed values in Tables 2 and 3e preparation of this British Standard was entrusted by the General nical Engineering Standards Policy Committee (GME/-) to Technical mmittee GME/9, upon which the following bodies were represented:Ltd.itish Constructional Steelwork Association Ltd.BS
6、7751-1:1994 BSI 2006ContentsPageCommittees responsible Inside front coverForeword ii1Scope 12 References 13 Definitions 14 Dimensions 15 Material 86Finish 87 Insert selection 88Instalation 99 Marking 10Annex A (informative) Insert selection 12Figure 1 Insert wire profile in finished coiled state 3Fi
7、gure 2 Dimensions of insert in free (unfitted) state 7Figure 3 Position of locking element in fitted insert 8Figure 4 Insert in fitted state 11Table 1 Dimensions of insert wire profile in finished coiled state 2Table 2 Dimensions of insert in free (unfitted) state 4Table 3 Position of locking elemen
8、t in fitted insert 8Table 4 Insert fitted length 9Table 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 class 12List of references Inside back coveriBS 7751-1:1994iiIt is a Part of a series for prev
9、ailing torque wire thread inserts.BS 7751-2 provides a specification for ISO metric fine pitch threads.This publication does not 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
10、from legal obligations.Summary of pagesThis document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 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 amendm
11、ent table on ForewordThis Part of BS 7751 has been prepared under the direction of the General Mechanical Engineering Standards Policy Committee. BSI 2006the inside front cover.BS 7751-1:19941 ScopeThis Part of BS 7751 specifies requirements for prevailing torque wire thread inserts which, when fitt
12、ed 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 and BS 3643-2:1981;c) give a frictional resistance
13、 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 BS 6293-2 may be used with these inserts.2 Referenc
14、es2.1 Normative referencesThis 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 the inside back cover. For dated references, only the edi
15、tion 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 publication applies, together with any amendments.2.2 Informa
16、tive referencesThis 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 made to the latest editions.3 DefinitionsFor the purposes o
17、f this Part of BS 7751, the following definitions apply.3.1 prevailing torque type wire thread inserta wire thread insert which, when installed in a hole tapped in accordance with BS 4377:1991, will provide a female thread containing a prevailing torque element. The frictional resistance of the prev
18、ailing torque element is of such a value that the 3.2 prevailing torque element (locking device)the coil(s) of the insert designed to impose friction between the insert and the installed male thread3.3 prevailing (locking) torquethe torque to be applied to maintain rotation of the male part relative
19、 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 elementNOTE There is no permanence of prevailing torque for indefinite reusability. The reusability should be determined by the application.4 Dimensions4.1 Insert wire
20、profileThe 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 insertThe dimensions of an unfitted insert shall be in accordance with Table 2 and Figure 2.The surface roughness of the insert wire in the finished
21、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 coil if it is present when measuring the insert outside diameter.NOTE 3 Since the relationship between the in
22、sert 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 sufficient to allow the tang to be broken off cleanly with a sharp blow after installation and then permit the through
23、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 Figure 3.NOTE The number, shape and orientation of the locking coils, the spacing between the locking coils and the
24、 number of faces on the locking coils are the sole responsibility of the manufacturer.4 BSI 2006 1insert is considered screw lockingBS 7751-1:1994Table 1 Dimensions of insert wire profile in finished coiled stateDimensions in millimetresThread size X W T Ediameter pitch min. max. min. max. min. max.
25、 min. max.M2.2M2.5M3M3.5M4M4.5M5M6M7M8M10M12M14M16M18M20M22M24M27M30M33M36M390.450.450.50.60.70.750.8111.251.51.75222.52.52.5333.53.5440.3330.3330.3680.4450.5210.5590.5970.7440.7440.9351.1251.3111.5011.5011.8801.8801.8802.2582.2582.6342.6343.0123.0120.3400.3400.3780.4550.5310.5690.6070.7570.7570.947
26、1.1381.3261.5161.5161.8951.8951.8952.2732.2732.6522.6523.0303.0300.4450.4450.4900.5940.6910.7370.7850.9860.9861.2421.5011.7602.0022.0022.4972.4972.4973.0283.0283.5283.5284.0564.0560.4880.4880.5410.6500.7570.8130.8661.0821.0821.3541.6231.8952.1642.1642.7052.7052.7053.2493.2493.7903.7904.3314.3310.323
27、0.3230.3580.4320.5030.5380.5740,7160,7160,8971,0771,2551.4351.4351.7931.7931.7932.1512.1512.5122.5122.8702.8700.3940.3940.4370.5260.6120.6550.7010.8740.8741.0951.3131.5321.7501.7502.1872.1872.1872.6242.6243.0633.0633.5003.5000.2740.2740.3070.3680.4340.4670.5000.6250.6250.7870.9501.1051.2671.2671.590
28、1.5901.5901.9151.9152.2382.2382.5632.5630.2920.2920.3250.3890.4550.4880.5210.6500.6500.8130.9751.1351.2981.2981.6231.6231.6231.9481.9482.2732.2732.5982.5982 BSI 2006BS 7751-1:1994NOTE See Table 1 for dimensions.Figure 1 Insert wire profile in finished coiled state BSI 2006 3BS 7751-1:1994Table 2 Dim
29、ensions of insert in free (unfitted) stateDimensions in millimetresThread size Outside diameterDNominal length No. of coilsNTang lengthLSpace for tangMdiameter, d Pitch min. max. min. max. min. max.1d 2.9 3.41.5d 5.1 5.6M2.2 0.45 2.8 3.0 2d 7.4 7.9 1.40 0.982.5d 9.6 10.13d 11.9 12.41d 3.1 3.61.5d 5.
30、5 6.0M2.5 0.45 3.20 3.70 2d 7.8 8.4 1.60 0.982.5d 10.2 10.83d 12.5 13.01d 3.5 4.01.5d 6.1 6.6M3 0.5 3.80 4.35 2d 8.6 9.1 1.90 1.082.5d 11.1 11.63d 13.5 14.11d 3.5 4.01.5d 6.1 6.6M3.5 0.6 4.39 4.95 2d 8.5 9.0 2.20 1.302.5d 11.1 11.63d 13.3 14.01d 3.3 3.91.5d 5.8 6.4M4 0.7 5.05 5.60 2d 8.3 8.9 2.50 1.
31、502.5d 11.0 11.63d 13.3 13.91d 3.7 4.31.5d 6.4 6.9M4.5 0.75 5.52 6.07 2d 9.3 9.9 2.62 1.632.5d 11.5 12.33d 14.4 15.01d 3.9 4.41.5d 6.6 7.1M5 0.8 6.25 6.80 2d 9.3 9.9 3.12 1.732.5d 12.1 12.64 BSI 20063d 14.8 15.4BS 7751-1:1994Dimensions in millimetresThread size Outside diameterDNominal length No. of
32、 coilsNTang lengthLSpace for tangMdiameter, d Pitch min. max. min. max. min. max.1d 3.8 4.31.5d 6.5 7.0M6 1 17.40 17.95 2d 9.2 9.8 3.70 2.202.5d 11.8 12.43d 14.6 15.21d 4.6 5.31.5d 7.7 8.3M7 1 18.65 19.20 2d 10.8 11.4 4.32 2.202.5d 13.6 14.43d 17.0 17.51d 4.2 4.81.5d 7.2 7.7M8 1.25 19.80 10.35 2d 10
33、.0 10.5 4.90 2.702.5d 13.0 13.53d 15.8 16.41d 4.6 5.11.5d 7.7 8.3M10 1.5 11.94 12.50 2d 10.8 11.4 5.97 3.272.5d 14.0 14.53d 17.1 17.61d 4.7 5.21.5d 8.0 9.0M12 1.75 14.30 15.00 2d 11.2 11.7 7.15 3.742.5d 14.4 14.93d 17.6 18.11d 4.8 5.41.5d 8.2 8.7M14 2 16.65 17.7 2d 11.5 12.0 8.32 4.332.5d 14.6 15.23
34、d 18.1 18.61d 5.8 6.31.5d 9.4 10.0M16 2 18.90 19.9 2d 13.2 13.7 9.45 4.332.5d 16.8 17.5Table 2 Dimensions of insert in free (unfitted) state (continued) BSI 2006 53d 20.7 21.4BS 7751-1:1994Dimensions in millimetresThread size Outside diameterDNominal length No. of coilsNTang lengthLSpace for tangMdi
35、ameter, d Pitch min. max. min. max. min. max.1d 5.1 5.61.5d 8.6 9.1M18 2.5 21.30 22.00 2d 12.0 12.5 10.65 5.412.5d 15.3 15.93d 18.7 19.21d 5.8 6.41.5d 9.6 10.1M20 2.5 23.55 24.40 2d 13.3 13.9 11.8 5.412.5d 17.1 17.73d 20.8 21.51d 6.5 7.01.5d 10.6 11.1M22 2.5 25.90 26.90 2d 14.6 15.1 12.95 5.412.5d 1
36、8.7 19.63d 22.8 23.81d 5.8 6.41.5d 9.7 10.2M24 3 28.0 29.1 2d 13.5 14.0 14.0 6.502.5d 17.2 17.73d 21.1 21.61d 6.7 7.21.5d 11.0 11.5M27 3 31.40 32.70 2d 15.2 15.7 15.70 6.502.5d 19.5 20.03d 23.7 24.21d 6.3 6.91.5d 10.2 11.0M30 3.5 35.10 36.30 2d 14.2 15.1 17.50 7.602.5d 18.2 19.03d 22.2 23.31d 7.6 8.
37、11.5d 12.3 12.8M33 3.5 38.15 39.40 2d 15.7 16.8 19.0 7.602.5d 20.1 21.3Table 2 Dimensions of insert in free (unfitted) state (continued)6 BSI 20063d 24.5 25.8BS 7751-1:1994Dimensions in millimetresThread size Outside diameterDNominal length No. of coilsNTang lengthLSpace for tangMdiameter, d Pitch m
38、in. max. min. max. min. max.1d 6.6 7.31.5d 10.8 11.6M36 4 41.85 43.25 2d 14.9 15.9 20.90 8.662.5d 19.1 20.33d 23.2 24.61d 7.7 8.11.5d 11.8 12.7M39 4 44.90 46.40 2d 16.4 17.4 22.45 8.662.5d 20.9 22.13d 25.4 26.71)See note 4 to 4.2.2)See note 3 to 4.2.Figure 2 Dimensions of insert in free (unfitted) s
39、tateTable 2 Dimensions of insert in free (unfitted) state (continued) BSI 2006 7BS 7751-1:1994Table 3 Position of locking element in fitted insertDimensions in millimetresThread size Nominal thread length1d 1.5d 2d 2.5d 3ddiameter, d pitch A B A B A B A B A Bmin. max. min. max. min. max. min. max. m
40、in. max.M2.2 0.45 0.4 1.4 1.0 2.0 1.5 2.5 1.5 3.1 1.5 3.6M2.5 0.45 0.6 1.6 1.2 2.2 1.8 2.8 1.8 3.5 1.8 4.1M3 0.5 0.7 1.6 1.5 2.4 2.2 3.1 2.2 3.9 2.2 4.6M3.5 0.6 0.8 2.2 1.7 3.1 2.6 3.9 2.6 4.8 2.6 5.7M4 0.7 0.9 2.5 1.9 3.5 2.9 4.5 2.9 5.5 2.9 6.5M4.5 0.75 1.1 2.8 2.2 3.9 3.4 5.1 3.4 6.2 3.4 7.3M5 0.
41、8 1.3 3.1 2.5 4.3 3.8 5.6 4.9 6.8 6.2 8.1M6 1 1.5 3.7 3.0 5.2 4.5 6.7 4.5 8.2 4.5 9.7M7 1 2.0 4.2 3.7 6.0 5.5 7.7 5.5 9.5 5.5 11.2M8 1.25 2.1 4.9 4.1 6.9 6.1 8.9 6.1 10.9 6.1 12.9M10 1.5 2.7 6.1 5.2 8.6 7.7 11.1 7.7 13.6 7.7 16.1M12 1.75 3.4 7.3 6.4 10.3 9.4 13.3 9.4 16.3 9.4 19.3M14 2 4.0 8.5 7.5 1
42、2.0 11.0 15.5 11.0 19.0 11.0 22.5M16 2 5.0 9.5 9.0 13.5 13.0 17.5 13.0 21.5 13.0 25.5M18 2.5 5.2 10.9 9.7 15.4 14.2 19.9 14.2 24.4 14.2 28.9M20 2.5 6.2 11.9 11.2 16.9 16.2 21.9 16.2 26.9 16.2 31.9M22 2.5 7.2 12.9 12.7 18.4 18.2 23.9 18.2 29.4 18.2 34.9M24 3 7.5 14.2 13.5 20.2 19.5 26.2 19.5 32.2 19.
43、5 38.2M27 3 9.0 15.7 15.7 22.5 22.5 29.2 22.5 36.0 22.5 42.7M30 3.5 9.7 17.6 17.2 25.1 24.7 32.6 24.7 40.1 24.7 47.6M33 3.5 11.2 19.1 19.5 27.4 27.7 35.6 27.7 43.9 27.7 52.1M36 4 12.0 21.0 21.0 30.0 30.0 39.0 30.0 48.0 30.0 57.0M39 4 13.5 22.5 23.2 32.2 33.0 42.0 33.0 51.7 33.0 61.55 MaterialThe ins
44、ert wire shall be manufactured from austenitic stainless steel of the type characterized as 18 % chromium, 8 % nickel.NOTE The precise composition is at the manufacturers discretion.6 FinishThe finished coiled insert shall be in the natural condition.7 Insert selectionThe length of insert selected s
45、hall be such that no stripping of the tapped hole in the parent metal into 8 BSI 2006Figure 3 Position of locking element in fitted insertwhich the insert is fitted occurs before tensile failure of the male threaded part that is screwed into the fitted insert.NOTE Annex A gives guidance on the selec
46、tion of insert length required for different grades of bolt and tapped parent material strengths.BS 7751-1:19948 InstallationThe insert shall be capable of being installed 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
47、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 therefore drawn to the importance of maintaining the tolerance requirements of BS 4377:1991.The insert fitted length shall be as given i
48、n 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).Table 4 Insert fitted lengthTable 4 Insert fitted lengthDimensions in millimetresThread size Nominal length Fitted lengthdiameter, d pitch
49、min. max.1d 1.75 1.971.5d 2.85 3.07M2.2 0.45 2d 3.95 4.172.5d 5.05 5.273d 6.15 6.371d 2.05 2.271.5d 3.30 3.52M2.5 0.45 2d 4.55 4.772.5d 5.80 6.023d 7.05 7.271d 2.50 2.751.5d 4.00 4.25M3 0.5 2d 5.50 5.752.5d 7.00 7.253d 8.50 8.751d 2.90 3.201.5d 4.65 4.95M3.5 0.6 2d 6.40 6.702.5d 8.15 8.453d 9.90 10.20Dimensions in millimetresThread size Nominal length Fitted lengthdiameter, d pitch min. max.1d 3.30 3.651.5d 5.30 5.65M4 0.7 2d 7.30 7.652.5d 9.30 9.653d 11.30 11.651d 3.75 4.121.5d 6.00 6.37M4.5 0.75 2d 8.25 8.622.5d 10.50 10.873d 12
