1、BRITISH STANDARD BS 7753:1994 Specification for Performance of prevailing torque wire thread inserts UDC 621.882.5.082BS7753:1994 This British Standard, having been prepared under the directionof the General Mechanical Engineering Standards Policy Committee, waspublished under the authorityof the St
2、andards Boardand comes into effect on 15 September 1994 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference GME/9 Draft for comment 92/84545 DC ISBN 0 580 23319 7 Committees responsible for this British Standard The preparation of this British Standard w
3、as 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 Industrial Fasteners Federation British Steel Industry British St
4、eel 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, through subcommittees and panels: Defence Manufacturers Associat
5、ion General Municipal Boilermaker and Allied Trades Union Screw Thread Tool Manufacturers Association Society of British Aerospace Companies Ltd. Amendments issued since publication Amd. No. Date CommentsBS7753:1994 BSI 08-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1
6、Scope 1 2 Normative references 1 3 Definitions 1 4 Performance requirements 1 5 Test plate 1 6 Torque measuring device 2 7 Test spacer 2 8 Test bolt 2 9 Test method 3 Figure 1 Dimensions of test plate 2 Figure 2 Position of installed insert in test plate 4 Table 1 Seating torque and prevailing torqu
7、e for inserts 1 Table 2 Dimensions of test spacers 3 List of references Inside back coverBS7753:1994 ii BSI 08-1999 Foreword This British Standard has been prepared under the direction of the General Mechanical Engineering Standards Policy Committee to provide performance requirements and test metho
8、ds for prevailing torque wire thread inserts that conform to BS7751-1:1994 or BS7751-2:1994. 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 no
9、t of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This wi
10、ll be indicated in the amendment table on the inside front cover.BS7753:1994 BSI 08-1999 1 1 Scope This British Standard specifies performance requirements and test methods for prevailing torque type self-locking wire thread inserts that conform to either BS7751-1:1994 or BS7751-2:1994. 2 Normative
11、references This British Standard 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 edition cited app
12、lies; any subsequent amendments to or revisions of the cited publication apply to this standard 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. 3 Definitions For the purposes
13、of this British Standard, the following definitions apply. 3.1 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 elemen
14、t NOTEThere is no permanence of prevailing torque for indefinite reusability. The reusability should be determined by the application. 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 seating tor
15、que the tightening torque to be applied to the insert to introduce or increase the axial load in the assembly 4 Performance requirements 4.1 The prevailing torque developed by the test insert up to the fifth assembly with the test bolt shall not exceed the maximum prevailing torque specified inTable
16、 1. In addition the prevailing torque developed up to the fifth removal of the test bolt from the assembly shall be not less than the values specified inTable 1 when tested in accordance with clause9. 4.2 At any time during the test specified in clause 9, the insert shall not rotate greater than 90
17、in either direction from its initial installed position in the test plate. 4.3 After testing in accordance with clause9, the thread shall conform to the original installed class of fit up to the point of engagement with the thread prevailing torque element as determined by a screw plug gauge. 4.4 Af
18、ter testing in accordance with clause 9, the insert shall show no evidence of distortion or cracking. 4.5 After testing in accordance with clause9, the insert and test bolt shall show no evidence of seizure or galling. Table 1 Seating torque and prevailing torque for inserts 5 Test plate The test pl
19、ate shall be manufactured from aluminium alloy in accordance with ISO6362-2:1990 AlCu4Mg1-T4(2024) to the dimensions given inFigure 1. Nominal size Seating torque Prevailing torque Nm diameter Nm max. 5th removal min. M2.2 0.38 0.14 0.02 M2.5 0.58 0.22 0.03 M3 1.0 0.43 0.06 M3.5 1.6 0.68 0.08 M4 2.4
20、 0.9 0.10 M4.5 3.7 1.3 0.13 M5 5.0 1.6 0.15 M6 8.0 3.0 0.25 M7 14 4.4 0.35 M8 20 6.0 0.45 M10 40 11 0.8 M12 70 16 1.2 M14 110 24 1.6 M16 170 32 2.2 M18 220 42 3 M20 320 55 3.8 M22 440 68 4.8 M24 550 82 6.0 M27 800 94 7.5 M30 1100 108 9.0 M33 1500 122 10.5 M36 2000 136 12.0 M39 2500 150 13.5BS7753:19
21、94 2 BSI 08-1999 6 Torque measuring device The torque measuring device (torque wrench or power device) shall be accurate to 2% of the torque specified for the insert on test. 7 Test spacer The test spacer shall be manufactured from hardened steel to the dimensions specified in Table 2. The surface f
22、inish shall be 16m CLA or better. The outside configuration of the spacer shall be such as to prevent rotation during the testing. The two bearing faces of the spacer shall be clean, flat and parallel within a tolerance zone of 0.02mm. 8 Test bolt The test bolt shall be threaded in accordance with B
23、S3643-1:1981 and BS3643-2:1981 within the tolerance class6g minimum to 4h maximum. The threads on bolts of 24mm diameter or less shall be produced by the thread rolling process. All bolt threads shall be natural finish. The test bolt shall be of sufficient length such that a minimum of three to five
24、 thread pitches, as measured from the end of the bolt, will protrude through the insert when the bolt head is seated up against the test spacer. NOTEIt is recommended that the bolt is of property class10.9minimum. Figure 1 Dimensions of test plateBS7753:1994 BSI 08-1999 3 Table 2 Dimensions of test
25、spacers 9 Test method The insert shall be assembled into the test plate (seeFigure 2) and the tang cleanly removed. The test bolt threads and the under-head abutment face shall be lubricated with a straight mineral oil conforming to BS4231:1992/ISO3448(ISOVG32) then assembled with the test spacer (s
26、ee clause7) and screwed into the insert fitted in the test plate. The test bolt shall be screwed into the insert until two to three full bolt threads protrude through the prevailing torque element of the insert. The prevailing torque that occurs while the bolt is screwed in through the next 360 of r
27、otation shall be measured. Tightening of the bolt shall then be continued until the seating torque specified inTable 1 is achieved. The test bolt shall then be slackened by a half turn and the prevailing torque that occurs as the test bolt is slackened through a further full turn shall be measured.
28、The test bolt shall continue to be slackened until it is fully disengaged from the prevailing torque element of the insert. The test shall be repeated four more times so that each test bolt/insert combination has been tightened and slackened five times in total. The prevailing torque shall be measur
29、ed using a device as specified in clause6. All prevailing torque measurements shall be taken with the test bolt (seeclause8) in motion. The speed of rotation of the test bolt during the testing shall not exceed 30rev/min and shall be continuous and uniform. Sufficient time shall be allowed to elapse
30、 between each test cycle to avoid overheating of the test assembly. The reference torque measuring device shall be a hand operated torque wrench. A new test bolt shall be used for testing each insert. Dimensions in millimetres Nominal size of bolt Internal diameter Diameter of bearing surface max. m
31、in. min. M2.2 3.0 2.9 5.0 M2.5 3.3 3.2 5.0 M3 3.8 3.7 5.0 M3.5 4.4 4.3 6.3 M4 4.9 4.8 6.3 M4.5 5.7 5.3 7.2 M5 5.9 5.8 7.2 M6 7.1 6.9 9.0 M7 8.5 8.3 11.7 M8 9.5 9.3 11.7 M10 11.5 11.3 15.3 M12 14.5 14.3 17.1 M14 16.5 16.3 19.8 M16 18.5 18.3 21.6 M18 20.5 20.3 24.4 M20 22.7 22.5 27.0 M22 24.7 24.5 28.
32、8 M24 26.7 26.5 32.4 M27 30.7 30.5 36.9 M30 33.9 33.5 41.4 M33 36.9 36.5 45.0 M36 39.9 39.5 49.5 M39 42.9 42.5 52.5 NOTEThe minimum thickness of the test spacer shall be such that the bolt thread run out does not enter the wire thread insert.BS7753:1994 4 BSI 08-1999 Figure 2 Position of installed i
33、nsert in test plateBS7753:1994 BSI 08-1999 List of references (see clause2) Normative references BSI publications BRITISH STANDARDS INSTITUTION, London BS 3643, ISO metric screw threads. BS 3643-1:1981, Principles and basic data. BS 3643-2:1981, Specification for selected limits of size. BS 4231:199
34、2, Classification for viscosity grades of industrial liquid lubricants. BS 4377:1991, Specification for tapping of holes to receive wire threads inserts (ISO metric threads). BS 7751, Prevailing torque type wire thread inserts. BS 7751-1:1994, Specification for ISO metric coarse pitch threads. BS 77
35、51-2:1994, Specification for ISO metric fine pitch threads. ISO publications INTERNATIONAL ORGANIZATION FOR STANDARDIZATION (ISO), Geneva. (All publications are available from BSI Customer Services) ISO 3448:1992, Industrial liquid lubricants ISO viscosity classification. ISO 6362, Wrought aluminium
36、 and aluminium alloy extruded rods/bars, tubes and profiles. ISO 6362-2:1990, Mechanical properties. BS 7753:1994 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standa
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