1、AECMA STANDARD NORME AECMA AECMA NORM Edition approved for publication 2000-10-31 prEN 4444 Edition P 1 October 2000 Comments should be sent within six months after the date of publication to Gulledelle 94 C8 Chairman AECMA Mr Feltham 8-1200 BRUXELLES PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPA
2、CE INDUSTRIES (AECMA) Gulledelle 94 - 8-1200 BRUXELLES - Tel. (+32) 2 5 81 10 - Fax. (+32) 2 775 81 11 ICs: 49.030.30 Descriptors: ENGLISH VERSION Aerospace series Nuts, elliptical clinch, self-locking, in heat resisting steel FE-PA2601 (A286), Mos2 coated Classification: 900 MPa (at ambient tempera
3、ture) I425 “C Technical specification Srie arospatiale Luft- und Raumfahrt Ecrous t6te elliptique, freinage interne, Einnietmutter, blind, elliptischer Kopf, selbstsichernd, en acier rsistant chaud FE-PA2601 (A286), aus hochwarmfestem Stahl FE-PA2601 (A286), revtus Mosz Mos2 beschichtet Classificati
4、on : 900 MPa Klasse: 900 MPa ( temprature ambiante) I425 OC (bei Raumtemperatur) I425 OC Spcification technique Technische Lieferbedingungen This “Aerospace Series“ Prestandard has been drawn up under the responsibility of AECMA (The European Association of Aerospace Industries). It is published on
5、green paper for the needs of AECMA- Members. It has been technically approved by the experts of the concerned Technical Committee following comment by the Member countries. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeabil
6、ity is affected, physically or functionally, without re-identification of the standard. After examination and signafure of the AECMA Standard Checking Centre (NPS) and formal agreement of the Oficial Services of the Member countries it will be submitted as a draft European Standard to CEN (European
7、Committee for Standardization) for formal vote. Nota - Extra copies can be supplied by B.N.A.E. - Technopolis 54 - 199. rue Jean-Jaques Rousseau - 92138 ISSY-LES-MOULINEAUX CEDEX Page 2 prEN 4444: 2000 Contents i 4 5 Scope 3 Normative references . 3 Terms and definitions 4 Quality assurance 6 Requir
8、ements 6 STDDAECMA PREN VVilY-ENGL 2000 LOL231L 0038879 0?18 = Page 3 prEN 4444: 2000 I Scope This standard specifies the characteristics, qualification and acceptance requirements for self-locking elliptical clinch nuts in FE-PA2601, for aerospace applications. Classification : 900 MPa 1) / 425 OC
9、2) It is applicable whenever referenced. 2 Normative references IS0 2859-1 IS0 3161 IS0 3452 IS0 3534-1 977 ISO 4288 IS0 5855-2 IS0 8642 EN 3042 EN 4446 ASTM EI 12-96 Sampling procedures for inspection -y attributes - Part I : Sampling sc, ,ernes indexed by acceptable quality limit (AQL) for lot-by-
10、lot inspection Aerospace - UNJ threads - General requirements and limit dimensions Non-destructive testing - Penetrant inspection - General principles Statistics - Vocabulary and symbols Geometrical Product Specifications (GPS) - Surface texture: Profile method - Rules and procedures for the assessm
11、ent of surface texture Aerospace - MJ threads - Part 2: Limit dimensions for bolts and nuts Aerospace - Self-locking nuts with maximum operating temperature greater than 425 OC - Test methods Aerospace Series - Quality assurance - EN aerospace products - Qualification procedure Aerospace series - Nu
12、ts, elliptical clinch, self-locking - Installation and removal procedure 3) Standard Test Methods for Determining Average Grain Size 4) 1) Corresponds to the minimum tensile stress which the nut is able to withstand at ambient temperature without breaking or cracking when tested with a bolt of a hig
13、her strength class. 2) Maximum test temperature of the parts 3) Published as AECMA Prestandard at the date of publication of this standard 4) Published by: American Society for Testing and Materials (ASTM), 1916, Race Street, Philadelphia, PA 19103, USA STD.AECMA PREN 4444-ENGL ZOOU 111 1012311 GOL8
14、900 blT I Page 4 prEN 4444: 2000 3 Terms and definitions For the purposes of this standard, the following terms and definitions apply. 3.1 batch quantity of finished nuts, of the same type and same diameter, produced from a material obtained from the same melt, manufactured in the course of the same
15、 production cycle, following the same manufacturing route and having undergone all the relevant heat treatments and surface treatments 3.2 Surface discontinuities 3.2.1 crack rupture in the material which may extend in any direction and which may be intercrystalline or transcrystalline in character
16、3.2.2 seam open surface defect 3.2.3 lap surface defect caused by folding over metal fins or sharp corners and then compressing them into the surface 3.2.4 inclusions non-metallic particles originating from the material manufacturing process. These particles may be isolated or arranged in strings. 3
17、.3 test temperature ambient temperature, unless otherwise specified 3.4 simple random sampling the taking of n items from a population of N items in such a way that all possible combinations of n items have the same probability of being chosen 5) 3.5 critical defect a defect that, according to judge
18、ment and experience, is likely to result in hazardous or unsafe conditions for individuals using, maintaining, or depending upon the considered product, or that is likely to prevent performance of the function of a major end item 5) 3.6 major defect a defect other than critical, that is likely to re
19、sult in a failure or to reduce materially the usability of the considered product for its intended purpose 5) 3.7 minor defect a defect that is not likely to reduce materially the usability of the considered product for its intended purpose, or that is a departure from established specification havi
20、ng little bearing on the effective use or operation of this product 5) STD-AECMA PREN L(L(L(L(-ENGL 2000 = 1012311 OOLB9OL 52b E Page 5 prEN 4444: 2000 3.8 sampling plan a plan according to which one or more samples are taken in order to obtain information and possibly to reach a decision 5) 3.9 lim
21、iting quality in a sampling plan, the quality level which corresponds to the specified 10 % probability of acceptance 3.1 O acceptable quality limit (AQL) a quality limit which in a sampling plan corresponds to a specified but relatively high probability of acceptance It is the maximum per cent defe
22、ctive (or the maximum number of defects per hundred units) that, for purposes of sampling inspection can be considered satisfactory as a process average 5). 3.1 I finished nut a nut ready for use, inclusive of any possible treatments andior surface coatings, as specified in the product standard or d
23、efinition document 3.12 definition document document specifying all the requirements for finished nuts 3.1 3 self-locking torque the torque to be applied to the nut or bolt to maintain its movement of rotation in relation to the associated part, the assembly being under no axial load and the nut loc
24、king zone being completely engaged with the bolt (minimum protrusion of two pitches, including the end chamfer) 3.14 seating torque the tightening torque to be applied to the nut or bolt to introduce or to increase the axial load in the assembly 3.1 5 breakaway torque the torque required to start un
25、screwing the nut or bolt with respect to the associated part, with the nut locking zone still fully engaged on the bolt, but after the axial load in the assembly has been removed by unscrewing half a turn followed by a halt in rotational movement 5) Definition taken from IS0 3534 Page 6 prEN 4444: 2
26、000 4 Quality assurance 4.1 Qualification EN 3042 Qualification inspections and tests (requirements, methods, numbers of nuts) are specified in table 1. They shall be carried out on: - each type and diameter of nut; - 42 nuts selected from a single batch by simple random sampling. The test programme
27、 may possibly be reduced, or the qualification be granted without inspection or testing: any such decision shall be based on the results obtained on similar types and diameters of nuts provided that the design and manufacturing conditions are identical. Table 2 indicates the allocation of nut sample
28、 for the inspections and tests. 4.2 Acceptance 4.2.1 Purpose The purpose of acceptance inspections and tests is to check, as simply as possible, by a method representative of actual use conditions, with the uncertainty inherent to statistical sampling, that the nuts constituting the batch satisfy th
29、e requirements of this standard. 4.2.2 Conditions Acceptance inspections and tests (requirements, methods, numbers of nuts) are specified in table 1. They shall be carried out on each batch. Nuts from the batch to be tested shall be selected by simple random sampling. Each nut may be submitted to se
30、veral inspections or tests. If a more stringent inspection is deemed necessary, all or part of the qualification inspections and tests may be performed during the acceptance inspection and testing. In this case, the number of nuts submitted to these inspections and tests is the same as that submitte
31、d for qualification inspection and tests. 4.2.3 Responsibility Acceptance inspections and tests shall be carried out by the manufacturer, or under his responsibility. 4.2.4 Inspection and test report A test report showing actual numerical values shall be provided if specified in the purchase order.
32、5 Requirements See table 1. STD-AECMA PREN VqVY-ENGL 2000 m LOL23LL 0038903 3T 6 Inspection and test method Page 7 prEN 4444 2000 Chemical analysis or certificate of conpliance issued by the manufacturer of the semi-finished product I Table 1 -Technical requirements and test methods Standard gauging
33、 - Ciau 1 - - ,2 - .3 .3.1 i.3.2 i.3.3 5.3.4 - continued The method of forming shall be indicated. :haractenstic laterlai A ilmensions, derances and derances of rm and mition Tables 3 and 4 Ilanufacuring :onning Q Q A rhread iefonnation :form ,ut-of-rou nd) 20 Tables 3 and 4 Surface roughness Molybd
34、enum disulphide (Motandard or definition document. The characteristics shall be nspeced at room temperature, quts shall be formed by a hot or mold forming process. f hot formed, the forming :emperature shall not exceed 1 150 C and they shall be air moled or faster. The equipment shall ensure a unifo
35、rm temperature throughout the production batch. Threads in the locking region may be deformed in any manner provided that the nut meets the requirements of this standard. Any tool marks must blend smoothly without any abrupt changes. The finished nuts shall allow the “GO“ thread plug gauge to enter
36、a minimum of i ,5 turns before engagement of the locking element. In accordance with the product standard or definition document Standard gauging IS0 4288 Visual examination A Sample size I I- Q I 20 QI 3 3 and 4 Tables 3 and 4 Page 8 prEN 4444: 2000 QIA Q Q Q Table 1 (continued) Sample sfz 4 4 3 Cl
37、aus 5.4 5.4.1 - 5.4.1.1 5.4.1.2 - 5.4.2 continued Characteristic Mechanical properties Axial load at ambient temperature after 425 C baking Permanent set test Requirement Finished nuts shall withstand the minimum loads specified in table 6, After the load has been applied the nut shall not display:
38、- any cracks; - any permanent set; - any significant reduction in thc locking torque of table 8. Finished nuts shall withstand the minimum loads specified in table 6. Mer testing, the nuts shall not display: - any cracks; - any fracture. Permanent set and resultant effects (reduction of the self- lo
39、cking torque) are permissible. 4 new test bolt shall be used for each axial tensile test. Permanent sets and their consequences (reduction or loss of self-locking torque) are acceptable Maximum locking toque shall not be greater than in table 7, when installed or removed from the “maximum mandrel“,
40、or be less than the minimum breakaway torque in table 7 when removed irom the “minimum mandrel“. Inspection and test method The nut shall be installed in a test block as specified in figure I and table 5 to instructions of prEN 4446. The bolt is defined in figure 2. IS0 8642. Use test block of type
41、A or B as defined in figure 1 and table 5. Uncoated bolts in material with Rp0,2 1 100 MPa Use test block of type B as defined in figure 1 and table 5 Uncoated bolts in material with RPO, I 100 MPa Tensile tests shall be carried out using assemblies soaked beforehand in a furnace to their maximum op
42、erating temperature (425 f 10) OC held at temperature for 6 h f 15 min then remove from the furnace and cooled to ambient temperature. IS0 8642 The nut shall be installed in a test block of type A as defined in figure 1 and table 5 to instructions of prEN 4446. Mandrels : see figure 3 and table 8. S
43、TD-AECMA PREN qq44-ENGL 2000 1012313 0038905 L73 Characteristic Page 9 prEN 4444: 2000 Reusability test Table 1 (continued) Self-locking torque at ambient temperature (1 5 cycles) - Clausi 4.3 - -4.3.1 A3.2 i.4.3.3 continued Self-locking torque at ambient temperature (three cycles) I General: Ater t
44、esting, nut threads shall not show any indications of distortion, galling or scratches of such a depth as to prevent reassembly of the nut freely, with the fingers, up to the self-locking element. Bolt threads shall remain serviceable and permit assembly of a new nut freely with the fingers up to th
45、e self-locking device. The nut temperature shall not exceed 45 C during screwing and unscrewing operations. The same items shall be used for the 15 cycles testing. Shall be to the minimum breakaway torque and the maximum self-locking torque, see table 7, for each cycle. The same items shall be used
46、for the five cycle testing. Shall be measured on each installation and removal and shall not exceed the self-locking torque, nor shall be less than the minimum breakaway torque given in table 7. Seif-iocking toque at ambient temperature after 425 “C baking (five cycles) Requirement The same items sh
47、all be used for the three cycle testing. The breakaway torque shall not be below the values in table 6 for the first, second and third cycle. The self-locking torque shall not exceei the values in table 6. NOTE This requirement may be combined with the 15 cycle requirement. During acceptance test, i
48、f the toque does not meet the requirements, perform the 15 cycle requirement. nspection and test method iee figure 4. ee table 9. Uuts shall be seated to the :orques in table 7, a total of 3 15. See table 9. The nuis to be tested shall be assembled with the test bolt and spacer and loaded to 520 MPa
49、. Loading shall be determined by measurement of elongation of the bolt at ambient temperature, using bolts having a shank diametei equal to the thread pitch diameter. The assembly shall be heated i a fuma to (425 f 8) “C and held at this temperature for 6 h f I5 min, removed from the furnace and cooled to ambient temperature. See table 9. Nuts shall be seated to the torques in table 7, a total of x 3. impie sizc 10 10 Table IO column E STD-AECMA PREN LJL(L(L(-ENGL 2000 II 1012311 00L890b O08 See figure 6. Introduce the bolt into the nut till its
