1、STD*AECflA PREN Li25b-ENGL 1997 1032313 0032385 733 H AECMA STANDARD prEN 4256 NORME AECMA Edition P 1 AECMA NORM January 1997 Edition approved for publication PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPACE INDUSTRIES (AECMA) Gulledelle 94 - 6-1 200 BRUXELLES - Tel. (32) 2 775 81 10 - Fax. (32)
2、2 775 81 11 C3 Chairman Comments should be sent within six months after the date of Dublication to ICs : 49.040.20 Descriptors : ENGLISH VERSION Aerospace series Nuts, anchor, self-locking, fixed, two lug, reduced series with counterbore, in heat resisting steel, silver plated Classification : 1 100
3、 MPa (at ambient temperature) / 425 OC Srie arospatiale crous river, freinage interne, fixes, double patte, srie rhduite, avec chambrage, en acier rsistant chaud, argents Classification : 1 100 MPa ( temprature ambiante) / 425 OC Luft- und Raumfahrt Annietmuttern, selbstsichernd, beiderseitiger verk
4、urzter Flansch, mit zylindrischer Aussenkung, aus hochwarmfestem Stahl, versilbert Klasse : 1 100 MPa (bei Raumternperatur) / 425 OC This “Aerospace Series“ Prestandard has been drawn up under the responsibility of AECMA (The European Association of Aerospace Industries). It is published on green pa
5、per 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 interchangeability is af
6、fected, physically or functionally, without re-identification of the standard. After examination and signature of the AECMA Standard Checking Centre (NPSI and formal agreement of the Official Services of the Member countries it will be submitted as a draft European Standard to CEN European Committee
7、 for Standardization) for formal vote. 1997-0 1-3 1 AECMA Gulledelle 94 B-1200 BRUXELLES Mr Arena I I aecma 19: Page 3 prEN 4256 1 Scope This standard specifies the characteristics of self-locking, fixed, iwo lug, anchor nuts, reduced series, with counterbore, in heat resisting steel, silver plated.
8、 Classification : 1 100 MPa / 425 “C 2, 2 Normative references IS0 3225 IS0 5855-2 IS0 5858 IS0 8788 EN 2000 EN 2424 EN 2786 EN 3042 TR 3791 Aerospace-Self-locking, fixed, two lug anchor nuts, reduced series, with counterbore, strength classification 1 1 O0 MPa and maximum operating temperature 235
9、“C. Aerospace - MJ threads - Part 2 : Limit dimensions for bolts and nuts Aerospace - Self-locking nut with maximum operating temperature less than or equal to 425 C - Procurement specification Aerospace - Fasteners - Tolerances of form and position for nuts Aerospace series - Quality assurance - EN
10、 aerospace products - Approval of the quality system of manufacturers Aerospace series - Marking of aerospace products 3, Aerospace series - Electrolytic silver plating of fasteners 3) Aerospace series - Quality assurance - EN aerospace products - Qualification Aerospace series - Materials for ail m
11、etal self-locking nuts and thin wall inserts of temperature classes 5 425 “C 4, 1) Corresponds to the minimum stress which the nut is able to withstand at ambient temperature, without breaking or cracking when tested with a bolt of a higher strength class. 2) Maximum temperature that the nut is able
12、 to withstand, without permanent alteration to its original characteristics, after ambient temperature has been restored. The maximum temperature is conditionned by the dimension. 3) Published as AECMA Pre-Standard at the date of publication of this standard Previous page is blank 4) Published as AE
13、CMA Technical Report at the date of publication of this standard STD=AECMA PREN 425b-ENGL 1997 3032333 0032387 50b = Page 4 prEN 4256 3 Required characteristics 3.1 Configuration - Dimensions - Masses See Figure 1 and Table 1. Dimensions and tolerances are : in conformity with IS0 3225, expressed in
14、 millimetres and apply after surface treatment. Details of form not stated are at the manufacturers option. The cap shall remain joined (type of attachment at the users discretion) to the nut at the maximum operating temperature. See test conditions in IS0 5858. 3.2 IS0 8788 Tolerances of form and p
15、osition. 3.3 Materials TR 3791 3.4 Surface treatment EN 2786, thickness : - on external surfaces: 5 pm to 15 pm ; - on pitch diameter : 5 pm minimum for nuts MJ6. Nuts MJ5 and smaller shall show complete coverage over complete profile. Remove sharp edges 0,l to 0,4 Y-Y I Marking Page 5 prEN 4256 in
16、this area to achieve the self-locking torque 8. requirement 2) Y hl Configuration with cap - 1) These values in micrometres apply before surface treatment. They do not apply to threads, punched holes or sheared edges, the surface texture of which will be as achieved by usual manufacturing methods. 2
17、) Tooling marks are permitted in this area. Figure 1 Table 1 IDiameter Thread 1) 7-T ) In accordance with IS0 5855-2 in the self locking zone the tolerances apply before forming out-of-round 2) Measured at sharp corners (chamfered) or point of tangency (radiuced) 3) Measured at rivet hole location 4
18、) Maximum protrusion of the bolt 5) Approximate values (kg/l O00 pieces), given for information purposes only. They apply to anchor nuts without cap STD=AECMA PREN Li25b-ENGL 1997 W 1012311 0012187 389 = Page 6 prEN 4256 4 Designation EXAMPLE : Description block I Identity block Nunber of this stand
19、ard Cap code (see table 2) Diameter code (see Table 1) NOTE : If necessary, the code 19005 shall be placed between the description block and the identity block. Table 2 I Code I Cap I I without I - (hyphen) I I I with I B I 5 Marking EN 2424, style N. See Figure I. 6 Technical specification IS0 5858 except for : - Approval of manufacturers : see EN 2000 ; - Qualification of products : see EN 3042.
