1、STD.AECMA PREN LiLiLib-ENGL 2000 10123Ll 0018928 779 D AECMA STANDARD NORME AECMA AECMA NORM prEN 4446 Edition P 1 October 2000 PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPACE INDUSTRIES (AECMA) Gulledelle 94 - 6-1200 BRUXELLES - Tel. (+32) 2 775 81 10 - Fax. (+32) 2 775 81 11 CS: 49.030.30 Descr
2、iptors: ENGLISH VERSION Aerospace series Nuts, elliptical clinch, self-locking Installation and removal procedure Srie arospatiale Luft- und Raumfahrt Ecrous tte elliptique, freinage interne Procdure dinstallation et dextraction Einnietmutter, blind, elliptischer Kopf, selbstsichernd Ein- und Ausbau
3、verfahren This “Aerospace Series“ Prestandard has been drawn up under the responsibilify of AECMA (The European Association of Aerospace Industries). It is published on green paper for the needs of AECMA- Members. It has been technically approved by the experts of the concerned Technical Committee f
4、ollowing comment by the Member countries. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. After examination and signature of the AECM
5、A Standard Checking Centre (NPS) and formal agreement of the Official Services of the Member countries it will be submitted as a draft European Standard to CEN (European Committee for Standardization) for formal vote. Nota. Extra copies can be supplied by B.N.A.E. - Te.chnopolis 54 - 199, rue Jean-J
6、acques Rousseau - 92138 ISSY-LES-MOULINEAUX CEDEX l Comments should be sent within six months after the date of publication to I Edition approved for publication 2000-1 0-31 AECMA Gulledelle 94 6-1200 BRUXELLES C8 Chairman Mr Feltham I I aecma 20( STD=AECMA PREN 44qb-ENGL 2000 D 3032333 0038929 b05
7、M Page 3 prEN 4446: 2000 1 Scope This standard specifies the manufacturing requirements of recesses, the conditions of installation and removal of self-locking elliptical clinch nut defined by EN standards, for aerospace applications. It shall be applicable whenever referenced. 2 Normative reference
8、s IS0 3161 Aerospace - UNJ threads - General requirements and limit dimensions IS0 5855-2 Aerospace - MJ threads - Part 2: Limit dimensions for bolts and nuts EN 4444 Aerospace series - Nuts, elliptical clinch, self-locking, in heat resisting steel FE-PA2601 (A286), Mos2 coated - Classification: 900
9、 MPa (at ambient temperature) / 425 “C - Technical specification 1) 1) Published as AECMA Prestandard at the date of publication of this standard Previous page is blank. Page 4 prEN 4446: 2000 3 Countersinking of installation hole Countersinking is carried out by moving a 90“ milling cutter along OF
10、-OF axis in order to comply with the characteristics of figure 1 and table 1. For information, the depth of the defined countersinks includes a negative flushness dimension of 0,l mm of the nut head. Dimensions in millimetres 9O“Il n 90“ *I Table I Dimensions in millimetres c, Key I 1 2 Displacement
11、 Chamfer 0,25 to 45“ for metallic item Figure 1 4 Installation 4.1 Condition of parts The conditions shall be as follows: - nut thread: clean and free from tearing; - elliptical head: free from any distortion or burr that could lead to faulty seating; - countersunk hole: clean and free from burr. ST
12、D.AECMA PREN qq4b-ENGL SODO W 101231L 0018931 2b3 M MJ6xl MJ7xl Page 5 prEN 4446: 2000 1 700/1 750 6,21/6,55 62/65 1 900/1 950 6,89/7,24 69/72 4.2 Installation and clinching The installation tooling includes: - a pressure generator and a pneumatic gun or equivalent equipment, enabling the maximum cl
13、inching pressures given in table 2 ; - an installation adapter defined by the manufacturer; - screw the nut on the full length of the mandrel of the corresponding adapter; - introduce the nuthandre1 assembly into the countersunk hole, then by a slight alternating rotation ensure that the head is cor
14、rectly positioned and is properly seated in the countersink; - proceed with the clinching operation after ensuring that the adjustment pressure of the generator is within the limit values given in table 2; - periodically check that the generator setting provides the clinching force given in table 2.
15、 Table 2 I Nut 1 Clinching force Generator pressure I thread daN 1 MPa I (bar) I MJ5x0,8 I 980/1 030 I 3,96/4,14 I 40/41 I MJ8xl I 2 050/2 100 I 7,58/7,93 I 76/79 I I lO.190 0-32UNJF-3B r 1 04511 085 I 3.62/3.96 I 36/40 1 10,2500-32UNJF-3B I 169011 730 I 6,20/6,55 I 62/65 I 10,312 5-24UNJF-3B I 2 29
16、512 335 I 7,93/8,27 1 79/83 I 10,375 0-24UNJF-3B I 3 780/3 820 I 12,75/13,10 I 127/131 I 4.3 Post-installation characteristics Ensure that: - the nut is correctly immobilized; - the elliptical head is properly seated in the countersink; - the negative flushness dimension of the nut head is correct;
17、- the self-locking is obtained using a non coated standard screw whose thread complies with IS0 5855-2 or IS0 3161. In case of doubt, record the value of the self-locking torque which shall remain within the limit values specified in EN 4444. NOTE In case of blind installation, take measurements on
18、test specimens. A slight marking on the nut head of a diameter equal to that of the installation tool tip is acceptable. STDmAECMA PREN LiLiLib-ENGL 2000 II LOL23LL OOL8732 LTT D Page 6 prEN 4446: 2000 4.4 Geometrical characteristics The dimensions of the clinch nut head shall remain within the limi
19、t values given in figure 2 and table 3. Nut thread MJ5x0,8 MJ6xl MJ7xl MJ8xl 0.190 0-32UNJF-3B 0,250 0-32UNJF-3B O 31 2 5-24UNJF-3B 0,375 0-24UNJF-3B Table 3 Dimensions in millimetres E L M X + 0,7 min. rnax. max. o 419 7,8 9,5 0,7 6,4 8,6 12 I ,5 7,05 I 10,4 I 143 I :i I 8,05 12,4 16,8 ru f -+-i- w
20、 l Figure 2 5 Disassembly - Repair Removal of a faulty or poorly-seated nut shall be carried out by re-working the end using a 90 centered milling cutter. The countersink shall be drilled to between 0,5 mm and 1 mrn from the support. The nut shall then be driven out using a suitable drift if the nut is driven into an inaccessible hollow structure and cannot then be removed (see figure 3). If removal of the faulty nut does not affect the countersink geometry, re-install an identical nut. If removal of the faulty nut damage to parent material another repair shall be find. Figure 3
