1、96/704900 DC Latest date for receipt of comments # ?+,e JGdE Project ND 96 1622 - Our ref ACE/12 Date ivhrch 1996 Technical Camittee ACE/12 Aerospace fasteners and fastening systems S“ “IS AND RINGS TFREADDED, SELF-LIXKING, IN FE-PA92HT (A286), SILVER PLATED ASSERIIBLY FLEXATIONS (TR 4239) This draf
2、t is now available for public comment and your views and technical comments on it would be appreciated. If you have no specific comments to make but fkd it generally acceptable it muid be helpful if you would noti us accordingly. Suggestions entailing revision of the text should indicate the preferr
3、ed wording. Please quote the relevant clause number against any comment. The co-ordination of the requirements of this draft with those of any related standards is of particular importance and you are invited to point out any areas where this may be necessary Ml comments should be sent to the Commit
4、tee Secretary Nni I S BURTON at the London address below. The comments received will be passed to the coinniittee concerned for its consideration; no acknowledgement will normally be sent. Requests for purchase of further copies of this draft should be sent to: Customer Services, at the head office
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6、EGARDED OR USED AS A BRITISH STANDARD Head office 389 Chiswick High Road London 5474 4-AL Telephone 0181 996 9000 Fax 0181 996 7400 BSI COMMITTEES TO WHOSE MEMBERS THIS DFGkFT HAS ALSO BEEN SENT STANDARDS COMMITTEE SUB-COMMITTEE ACE/12/1 AEROSPACE FASTENERS & FASTENING SYSTEMS (INTERNATIONAL) CONSTI
7、TUTION ORGANIZATIONS REPRESENTED _-_-_-_ -_-_-_-_- BRITISH INDUSTRIAL FASTENERS FEDERATION FEDERATION OF THE ELECTRONICS INDUSTRY MINISTRY OF DEFENCE MINISTRY OF DEFENCE SOCIETY OF BRITISH AEROSPACE COMPANIES LIMITED - A2 - 96/704900 239 ACE STAN This DPC refers to a draft text currently at the PPN
8、ballot stage within a technical committee of AECMA (The European Association of Aerospace Industries). The voting period within the AECMA. technical committee is two months from the date of dispatch of the document and this will be completed before the expiry ofthe DPC comment date. Any comments rec
9、eived as a result of the DPC, after the expiry of the PPN ballot, will be reviewed by the relevant BSI committee and taken into account when they consider the UK view and vote on a possible BS EN publication. ) AECMA consists of the national aerospace trade associations from nine European countries,
10、 the UK member being SBAC ( Society of British Aerospace Companies). AECMA has been given a mandate by CEN to prepare all European Aerospace Standards on its behalf. 96/7049OODC T 2nd draft proposal 07/95 Master docament Sponsor: Mr. BRESS ng Inner rings gned to be used Figure 1 eeisabll ity of shaf
11、t nuts and threae rin S maR deens QR &he Qbserance and threaded rings shall be of required self-l osking torque vai ues o Shaft nut - a ualflaton test (1 at ambent tmperature and tested according eo Technical specification EN 32 9 whsh requre $lent temprature after to max. test tperatur of 4 ecial n
12、$stn eque i .e, ade$ and To verify that the requr seling torques can be ache, two sizes f shaft nuts (27 mm and 57 mrn) Rad been tested ndrls accor ing to EN 329 s these mandrels had nominal pitch amete ter equal to he arthmetc mean of ma, and min. thread itch $ate of oerane class h gwi tk mnuatur n
13、g to1 erance k0,OO and a wear limit of -0,020 in relation to the sel al valu they were called “mean andrels These mean made cover only a small ran of the possible pitch diameter toeane class 4 of the shaft thread. Therefore slf-lon torques were addtional tested with mandrels repre- senting the upper
14、 limits (“mx. andres“ and lower limits (“min. adels) of the pitch diameter tolerance class 4g of the shaft thread. ax. and min, mandrels were new (IQW surface roughness), whereas mean mandrels were already used (higher surface uhn$s) The results of these tests were as follows: - The measured sel f-l
15、ocking torques were cnsdral luenced by the surfa- ce ondton of the manrls - At the beginnin of the test the mean mandrel s, lthough smaller in size than the max. ma drels, provided h9gher self-lsckin torques due to higher surface roughness. However, at the end of the test, the se-on torques were ien
16、eical to or smaller than those oned with the min. mandrels due to the abraon the shaft nut had undergone as it was asrewed and nscrewed - The min. mandrels ith lw surface roughness provided sel f-l ocking trques which were, Por a wide range, below the lower “limits as required according to EN 3299,
17、thus limn the number of reuses. - Due to the strong influece sf surface condition of the mandrels it was not possible to show a definite allocation of mandrel sizes and self-locking torques * - Among the two tested shaft nut sizes the following tendency appears: For larger shaft nuts it is more diff
18、icult to reach the minimum self-locking torque requirements of EN 329 for a greater number of reuses, a) The testing of self- orques of shaft nuts wi drels causes a high hfch does not rove determnaton of s ng trques than testing ith REan anrls herefore the testin -locking tQrqUes Shall b done with e
19、 man- re3 s according to E ue to the implicit crain of the slf-ljn shall not take for sft nuts ho se C) The conseuences for aetab use of these shat nuts are that the atual sel $-I ocking torqu s of the shaft nuts on the apropre shafts shall . be measured at every a sernbly to decide the sel f-l ock3
20、 ng rues are still thn the required limits accor ing to EN 3299. hether Shaft nu%s which do not provi e required used, i. e. torques shall be replace selfckn toues shall not $e even new sh ft nuts which do not provide ruired self-lac ltou influences in determination of sel f-locking torques can be e
21、xpected. threaded rings had not been tested analogous to clause 3.3, the s.ame The same comeRation as for shaft nuts ccordin to clause 3. also apply to threaded rings. Any rotation of shaft nuts or %hreae rings around their axis induces a cen- r$ force K on each of their alue measured at rest. earns
22、 whh modifies the slcg torque For threaded rings accordln 3296 or EN 3729 (see figure 31, this ten- tri fugal force K contributes rease the caing force t on each beam and increases. * the se$-locn torque value increases when the otatoa speed On the contrary, for shaf% nuts accor ta EM 3295 or E (see
23、 fjgure 419 this sentrifugal force K tends to decrease the clin force L on each beam and therefore I the sel f-l ocking torque val ue decreases when the rotatio- nal speed increases. Figure 3 Figure It .Is possible to calculate th residual lflocn torue value for rotational speed according to the foo
24、 formula: with : = residual slfocn tarue value for the i ven rotati onal speed itch iaeer m according to %SO 585 far one beam 9 cal cul ated accordi n NOTE i) If (L - K) 2 O, there is na residual self-locking torque for the given rotational speed and the shaft nut stays in place only due ta the fric
25、tional forces existing on any nut without elflocng feature. NOTE 2) The friction factor %a take into account depends on several parameters (material surface rounes and coating, urcatn etc. 1 Gener- ally spezking, it ia located between 0,08 and 0,12. Page 7 9 * *F. With = beam mass kg B, E and G Em, see figure 5 %i2 = thread pitch diameter m, according ta %SO 58 F = beam width m, see figure 5 = material density k with: R = beam center of gravity gyration radius m A, B, E and G m, see figure 5 Dg! = thread pitch diameter m, according to %SO 5855-1
