1、CEN PRENu3752 94 3404589 0080987 L2T H Edition approved for publication AECMA STANDARD NORME AECMA AECMA NORM Comments should be sent within six months C8 Chairman after the date of publication to prEN 3752 Edition P 1 December 1994 DIT PAR LASSOCIATION EUROPENNE DES CONSTRUCTEURS DE MATRIEL AROSPAT
2、IAL Technopolis - 175, rue Jean-Jacques Rousseau - F-92138 Issy-les-Moulineaux Cedex - Tl. (1) 47.36.98.76 UDC : Descriptors : ENGLISH VERSION Aerospace series Nuts,self -locking, M J threads, in heat resisting steel FE-PA92HT (A286), Mos2 coated Classification : i 100 MPa (at ambient temperature) /
3、 425 OC Technical specification Srie arospatiale Luft- und Raumfahrt crous, freinage interne, filetage MJ, en acier rsistant chaud FE-PA92HT (A2861, Muttern, selbstsichernd, MJ-Gewinde, aus hochwarmfestem Stahl FE-PA92HT (A2861, revtus Mos2 Mos2 beschichtet Classification : 1 100 MPa Klasse : 1 100
4、MPa ( temperature ambiante) / 425 OC (bei Raumtemperatur) I425 OC Spcification technique Technische Lieferbedingungen This “Aerospace Series“ Prestandard has been drawn up under the responsibility of AECMA (Association Europenne des Constructeurs de Matriel Arospatial). It is published on green pape
5、r 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 affe
6、cted, physically or functionally, without re-identification of the standard. After examination and signature of the AECMA 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 f
7、or Standardization) for formal vote. 1994-1 2-1 6 AECMA Technopolis - 175, rue Jean-Jacques Rousseau 92 138 Issy-les-Moulineaux Cedex - FRANCE Mr Williams 0 aecma 1994 CEN PRENt3752 94 3404589 0080988 066 Page 2 prEN 3752 : 1994 Contents list 1 Scope 2 Normative references 3 Definitions 4 Quality as
8、surance 5 Requirements CEN PREN*3752 94 3404589 0080787 TT2 Page 3 prEN 3752 : 1994 1 Scope This standard specifies the characteristics, qualification and acceptance requirements for self-locking nuts with MJ threads in FE-PA92HT, Mos2 coated. Classification 1 100 MPa I425 OC 2). It is applicable wh
9、enever referenced. 2 Normative references IS0 2859-1 IS0 3452 IS0 3534-1 977 IS0 4288 IS0 5855-2 IS0 7481 EN 2491 EN 3042 ASTM EI 12-88 Sampling procedures for inspection by attributes - Part 1 : Sampling plans indexed by acceptable quality level (AQL) for lot-by-lot inspection Non destructive testi
10、ng - Penetrant inspection - General principles Statistics - Vocabulary and symbols Rules and procedures for the measurement of surface roughness using stylus instruments Aerospace - MJ threads - Part 2 : Limit dimensions for bolts and nuts Aerospace - Fasteners - Self-locking nuts with maximum opera
11、ting temperature less than or equal to 425 OC - Test methods Aerospace series - Molybdenum disulphide dry lubricants - Coating methods 3, Aerospace series - Quality assurance - EN aerospace products - Qualification procedure Standard Test Methods for Determining Average Grain size 4, 1) Corresponds
12、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 higher strength class. 2) Maximum test temperature of the parts 3) In preparation at the date of publication of this standard 4) Published by : American S
13、ociety for Testing and Materials (ASTM), 1916 Race street, Philadephia, PA 19103, USA CEM PREN*3752 94 3404589 0080970 714 Page 4 prEN 3752 : 1994 3 Definitions For the purposes of this standard, the following definitions apply : 3.1 Production batch Quantity of finished nuts manufactured, using the
14、 same process, from a single material cast (single heat of alloy), having the same number (of product standard or definition document), thread code and diameter, heat treated together to the same specified condition and produced as one continuous run. 3.2 Inspection lot Quantity of nuts from a singl
15、e production batch with the same number (of product standard or definition document) which completely defines the nut. 3.3 Discontinuities 3.3.1 Crack : Rupture in the material which may extend in any direction and which may be intercrystalline or transcrystalline in character. 3.3.2 Seam : Open sur
16、face defect 3.3.3 forging them into the surface. Lap : Surface defect caused by folding over metal fins or sharp corners and then rolling or 3.3.4 particles may be isolated or arranged in strings. Inclusions : Non-metallic particles originating from the material manufacturing process. These 3.4 Test
17、 temperature Ambient temperature, unless otherwise specified 3.5 Simple random sampling The taking of n items from a population of N items in such a way that ali possible combinations of n items have the same probability of being chosen 5). 3.6 Critical defect A defect that, according to judgement a
18、nd 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 l. 3.7 Major defect A defect other than critical, that is likely to result i
19、n a failure or to reduce materially the usability of the considered product for its intended purpose ). 3.8 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 having lit
20、tle bearing on the effective use or operation of this product 5). CEN PRENx3752 94 3404589 0080993 b50 E Page 5 prEN 3752 : 1994 3.9 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). 3.10 Limiting quality In a sa
21、mpling plan, the quality level which corresponds to the specified 10 % probability of acceptance. 3.1 1 Acceptable quality level (AQL) A quality level which in a sampling plan corresponds to a specified but relatively high probability of acceptance. It is the maximum per cent defective (or the maxim
22、um number of defects per hundred units) that, for purposes of sampling inspection can be considered satisfactory as a process average 3.12 Finished nut A nut ready for use , inclusive of any possible treatments and/or surface coatings, as specified in the product standard or definition document. 3.1
23、3 Definition document Document specifying all the requirements for finished nuts 3.14 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 locking system being compl
24、etely engaged with the bolt (minimum protrusion of two pitches, including the end chamfer). 3.15 Seating torque The tightening torque to be applied to the nut or bolt to introduce or to increase the axial load in the assembly. 3.16 Unseating torque The untightening torque to be applied to the nut or
25、 bolt to reduce or remove the axial load in the assembly. 3.17 Breakaway torque The torque required to start unscrewing the nut or bolt with respect to the associated part, with the nut locking device still fully engaged on the bolt, but after the axial load in the assembly has been removed by unscr
26、ewing half a turn followed by a halt in rotational movement. 3.18 Wrench feature torque The torque to be applied to the wrenching feature of the nut. 5) Definition taken from IS0 3534 CEN PRENr3752 94 W 3404589 O080992 597 D Page 6 prEN 3752 : 1994 4 Quality assurance 4.1 Qualification EN 3042 Quali
27、fication 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 ; - 46 nuts selected from a single inspection lot by simple random sampling. The test programme may possibly be reduced, or the qualificati
28、on of a nut 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 specimens for the inspections and tests.
29、 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 the requirements of this standard
30、. 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 production batch or inspection lot. Nuts from the batch or lot to be tested shall be selected by simple random sampling. Each nut may be submitted
31、 to several 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 su
32、bmitted 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 o
33、rder. 5 Requirements See table 1. I Inspection and test method :hemical analysis of .ertificate of conformity ssued by the manufacturer if the semi-finished product ;tandard gauging CEN PRENa3752 94 3404589 0080993 423 M Clause 5.1 5.2 5.3 - 5.3.1 - 5.3.2 5.3.2.1 Page 7 prEN 3752 : 1994 Table 1 - Te
34、chnical requirements and test methods :haracteristic naterial limensions, olerances and olerances of orm and iosition ulanufacturing -arming Heat treatment Solution and precipitation heat treatmer Requirement i accordance with the product tandard or definition document n accordance with the product
35、;tandard or definition document Juts shall be formed by a hot or :old forming process. f hot formed, the forming :emperahre shall not exceed I 150 OC and they shall be air :ooled or faster. The equipment shall ensure a Jniform temperature throughout the production batch. The heat treatment medium or
36、 atmosphere shall not cause any surface contamination except as permitted by 5.5.5. Any scale which will not be removed by subsequent machining shall be removed by abrasive blasting. Solution treat (if applicable) at a temperature of 900 OC to 980 OC held at the selected temperature within I 15 OC f
37、or between 1 h min. and 2 h max. quench in oil, or alternative medium or faster. Precipitation treat at 720 OC + 10 OC held at temperature for 16 h I 15 min cooled in air or faster. The method of forming shall )e indicated. Calibration of the heat treatment equipment shall be confirmed. Appropriate
38、equipment LIA I O A - - Q A - O Page 8 prEN 3752 : 1994 Inspection and test method Table 1 (continued) QIA ) - Clai 5.3.3 - 5.3.4 5.3.5 5.3.6 See EN 2491. 3.4 - O A Characteristic Bearing surface perpendicularity Thread deformation (form out of round) Surface roug hness Surface coating Mechanical pr
39、operties Requirement In accordance with the product standard or definition document. For non-floating plate nuts having a bearing surface exceeding 1,5 times the thread nominal diameter, the perpendicularity requirement shall, unless otherwise specified by the product standard or definition document
40、, apply only to that portion of the bearing surface of the part contained within a diameter equal to 1,5 times the thread nominal diameter. Threads in the locking region may be deformed in any manner provided that the nut meets the requirements of this standard. Any tool marks shall blend smoothly w
41、ithout any abrupt changes. The finished nuts shall allow the “GO“ thread plug gauge to enter a minimum of three turns before engagement of the locking element for nuts having overall length of thread portion not less than 1,2 times the nominal thread diameter. After coating a bolt with IS0 5855-2 th
42、reads shall be able to be hand threaded 1,5 turns minimum in the nut. Finished nuts having shorter threaded portion shall allow the “GO“ thread plug gauge to enter a minimum of three quarters of a turn. In accordance with the product standard or definition document prior to surface coating In accord
43、ance with the product standard or definition document A test sample shall be selected from each size of bar, wire, sheet or strip taken from each cast, and shall be heat treated together with a production batch of nuts. The sample selected shall be sufficient to provide tensile test pieces. The test
44、 pieces shall meet the mechanical properties required by the material standard. SO 7481 l-3- t+ IS0 4288 - Visual :xamination ;ample size 46 Tables 3 and 4 46 Tables 3 and 4 3 Tables 3 and 4 43 Tables 3 and 4 (continued) - Clau - 5.4.1 5.4.1. 5.4.1. 5.4.2 5.4.3 5.4.3. CEN PRENx3752 94 3404589 008099
45、5 2Tb Page 9 prEN 3752 : 1994 Table 1 (continued) Characteristic 4xial load 4s received at ambient iemperature After 425 OC oaking Wrench feature test Vibration test As received at ambient temperature Requirement %shed nuts shall withstand :he minimum loads specified in ;able 5. 9fter the load has b
46、een applied the nut shall not display : - any cracks ; - any permanent set : - any significant reduction in self- IOCkinQ torque. %shed nuts shall withstand the minimum loads specified in table 5. 4fter testing, the nuts shall not jisplay : - any cracks ; - any fracture. ?ermanent set and resultant
47、effects reduction of the self-locking torque) are permissible. All wrenchable nuts shall withstand 15 successive applications of the torque specified in table 5 without any permanent damage to the wrench feature. After the test, rotation of the nut relative to the bolt less than or equal to 360 is p
48、ermissible. The nut shall not be cracked and shall not be capable of turning by hand. See 5.4.3. Inspection and test method IS0 7481 100 % test IS0 7481, 100 % test Prior to testing, the nut shall be assembled on a bolt of the same material, at least two thread pitches protruding. The assembly shall
49、 be heated to i425 + 8) OC and held at this temperature for 6 h 2 15 min and cooled to ambient temperature. Remove the nut from the bolt and proceed in accordance with IS0 7481. A new test bolt shall be used for each nut to be tested. IS0 7481 IS0 7481 cycles : 30 O00 total displacement : 1 1,25 mm Seating torque to be applied, see table 3. See 5.4.3. Q/A ) - O A O Q - Q iample size 4 Table 6, column B A 3 5 (continued) CEN PREN*3752 74 3404589 008099b 132 W Page 10 prEN 3752 : 1994 Table 1 (continued) - Claus 5.4.3.2 - 5.4.4 - 5.4.5 5.4.5.1 Characterist
