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1、STDmISO 748L-ENGL 2000 4853903 OBL52b0 347 I NTE R NATI O N AL IS0 STANDARD 7481 Second edition 2000-02-01 Aerospace - Nuts, self-locking, with maximum operating temperature less than or equal to 425 O C - Test methods Aronautique et espace - Ecrous freinage interne dont la temprature maximale dutil
2、isation est infrieure ou gale 425 “C - Mthodes de contrle et dessai Reference number IS0 7481:2000(E) 0 IS0 2000 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo re
3、production or networking permitted without license from IHS -,-,- STD-ISO 7Y83-ENGL 2000 4853703 08352bL 283 IS0 7481 :2000(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless th
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6、unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. o Is02000 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, includi
7、ng photocopying and microfilm, without permission in writing from either IS0 at the address below or ISOs member body in the country of the requester. IS0 copyright office Case postale 56 CH-121 1 Geneva 20 Tel. + 41 22 749 O1 11 Fax +41227341079 E-mail copyrightOiso.ch Web www.iso.ch Printed in Swi
8、tzerland II O IS0 2000 - All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or networking permitted without license from IHS -,-,- ST
9、D-IS0 7481-ENGL 2000 = 4853903 0815262 11T IS0 7481 :2000(E) Contents Page Foreword . iv 1 2 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.1 1 3.12 Scope 1 Normative references 1 Inspections and tests 2 Hardness test . 2 Bearing surface squareness test . 2 Axial load test . 4 Stress embrittlement tes
10、t 7 Torque-out test 8 Test of no rotation of the captive washer . 9 Push-out test 10 Self-locking torque at ambient temperature . 12 Permanent set test . 15 Vibration test 16 Wrenching feature test 6 Self-locking torque at ambient temperature after heat soak at maximum operating temperature . 14 O I
11、S0 2000 -All rights resewed iii Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or networking permitted without license from IHS -,-,- STD-IS0 7481-EN
12、GL 2000 4853903 OB15263 O56 IS0 7481 :2000(E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each mem
13、ber body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International El
14、ectrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voti
15、ng. Publication as an International Standard requires approval by at least 75 O h of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. IS0 shall not be held responsible for identifying
16、 any or all such patent rights. International Standard IS0 7481 was prepared by Technical Committee ISOTTC 20, Aircraft and space vehicles, Subcommittee SC 4, Aerospace fastener systems. This second edition cancels and replaces the first edition (IS0 7481:1984), which has been technically revised. N
17、otably, a test for no rotation of the captive washer was added. iv O IS0 2000 - All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or
18、 networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD IS0 7481:2000(E) Aerospace - Nuts, self-locking, with maximum operating temperature less than or equal to 425 O C - Test methods 1 Scope This International Standard specifies test methods for metric self-locking nuts with MJ
19、 threads intended for use in aerospace construction at maximum operating temperatures less than or equal to 425 OC. It describes the test device and the method for each test. It applies to self-locking nuts as defined above, provided that the relevant documents (dimensional standard, drawing, procur
20、ement specification, etc.) refer to this International Standard. This International Standard shall be used in conjunction with IS0 5858. NOTE applications at less than ambient temperatures, for example cryogenic, shall be as agreed upon between seller and purchaser. This International Standard only
21、specifies tests for ambient and elevated temperature applications. Tests for 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this international Standard. For dated references, subsequent amendments to, or rev
22、isions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the norm
23、ative document referred to applies. Members of IS0 and IEC maintain registers of currently valid International Standards. IS0 691 :1997, Assembly tools for screws and nuts - Wrench and socket openings - Tolerances for general use. IS0 1024:1989, Metallic materials - Hardness test - Rockwell superfic
24、ial test (scales 15N, 30N, 45N, 15T. 30T and 45T). IS0 5855-2:1999, Aerospace - MJ threads - Part 2: Limit dimensions for bolts and nuts. IS0 5858:1999, Aerospace - Nuts, self-locking, with maximum operating temperature less than or equal to 425 “C - Procurement specification. IS0 6507-1 : 1 997, Me
25、tallic materials - Vickers hardness test - Part 1: Test method. IS0 6508-1:1999, Metallic materials - ockwell hardness test - Part 1: Test method (scales A, B, C, 0, E, F, G, H, K, N, T). IS0 7403:1998, Aerospace - Spline drives - Wrenching configuration - Metric series. O IS0 2000 -All rights reser
26、ved 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or networking permitted without license from IHS -,-,- STDmISO 7481-ENGL 2000 4851903 0615265 92
27、9 W IS0 7481:2000(E) 3 Inspections and tests 3.1 Hardness test 3.1.1 Procedure The choice depends on the configuration of the nut and available equipment. The authorized procedures are: - Rockwell hardness in accordance with IS0 6508-1 ; - Vickers hardness HV 5 to HV 100 in accordance with IS0 6507-
28、1; - Rockwell superficial hardness in accordance with IS0 1024; - microhardness. 3.1.2 Method This test shall be carried out at ambient temperature. The measurement zone (bearing surface, across flats, underside of anchor nut lugs, etc.) shall correspond to the following conditions: a) thickness at
29、least equal to 10 times the penetration depth; b) parallelism with respect to bearing surface not greater than 3“. Should this not be possible, carry out this test on a cut section after moulding the nut into thermosetting resin. Remove all possible coating (protection, lubrication, paint, etc.) in
30、the measurement zone. Align the bearing surface to obtain the required relationship. These two operations shall not generate any heat liable to modify the characteristics of the material constituting the nut being tested. Carry out the test and then check conformity with the requirements of the dime
31、nsional standard or drawing. Nuts subjected to this test shall not be used again. 3.2 Bearing surface squareness test 3.2.1 Test device The test device is illustrated in Figure 1. The test device includes the following elements: a) a threaded mandrel with end in accordance with IS0 5855-2, with the
32、exception of the pitch diameter which shall be in accordance with the values specified in Table 5 for the maximum mandrel; b) a collar sliding on the plain portion of the threaded mandrel whose external diameter B is at least equal to reference dimension A for type I, II and V nuts in Figure 2 and e
33、qual to reference dimension A for type III and IV nuts in Figure 2; c) an appropriate feeler gauge. 2 O IS0 2000 -All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2
34、007 00:28:33 MDTNo reproduction or networking permitted without license from IHS -,-,- STD-ISO 7483-ENGL 2000 4853903 OB35thb 865 W IS0 7481:2000(E) Dimensions in millimetres 2 Key 1 Sliding collar 2 Threaded mandrel 3 Feeler gauge I I NOTE For clinch nuts, the sliding collar shall have a counterbor
35、e to accommodate the shank. a Pitch diameter Figure 1 Type I Type II Wrench nuts and clinch nuts Type 111 Type IV b) a conical washer (for testing countersunk nuts): c) a bolt with characteristics as follows: 1) 2) threads: in accordance with IS0 5855-2, tensile strength class: greater than that of
36、the nut under test, 3) material and coating: no specific requirement. 3.3.2 Method The axial load is transmitted to the nut by the bolt, the nut resting on the bearing plate. For countersunk nuts, a conical washer is interposed. 3.3.2.1 80 % test This test shall be carried out at ambient temperature
37、. Lubricate the bolt and nut threads as stated in Table 1 (if necessary). Assemble the bearing plate, and possibly the conical washer, onto the bolt. Assemble the nut and measure the locking torque when the protrusion is two pitches minimum (including chamfer). Position the assembly on the tensile m
38、achine. Apply the load slowly and progressively. Reduce the load slowly and progressively when the value quoted in the procurement specification has been reached. Remove the assembly from the tensile machine. Unscrew the nut a half-turn and cease movement, then again unscrew and measure the breakawa
39、y torque. Remove the nut, then submit it to a visual examination, and if necessary, an examination at a magnification of x 10 after sectioning, to check conformity with the requirements of the procurement specification. 4 O IS0 2000 -All rights reserved Copyright International Organization for Stand
40、ardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or networking permitted without license from IHS -,-,- STD-IS0 748L-ENGL 2000 Y851903 0815268 638 IS0 7481 :2000(E) Additional Locking Material Coat
41、ing Material Coating lubrication Nut to be tested Test bolt Plastic insert Any Any Alloy steel Cadmium None I Dimensions in millimetres d Steel or alloy steel Stainless steel Metallic Wrench nuts and Countersunk anchor nuts Clinch nuts Floating anchor nuts non-countersunk anchor nuts and gang channe
42、l nuts Any Alloy steel Cadmium None Silver Stainless steel None . or MOS:, Synthetic oil Key 1 Washer to fit countersink a Thickness D b Maximum shank diameter 1;:; C d Chamfer to suit the nut radius The hole shall allow the specified float. Figure 3 I None I Stainless steel I Silver 3.3.2.2 100 Y O
43、 test This test shall be carried out at ambient temperature. If the test includes a heat soak, then heat the nut and maintain it at the temperature quoted in the procurement specification. Take the nut from the oven and allow it to cool slowly to ambient temperature, then proceed as follows. Lubrica
44、te the bolt and nut threads as specified in Table 1 (if necessary), assemble the bearing plate and, if required, the conical washer, onto the bolt. Assemble the nut with a protrusion of two bolt pitches minimum (including chamfer) . Position the assembly on the tensile machine and apply the load slo
45、wly and progressively. Reduce the load slowly and progressively when the value quoted in the procurement specification has been reached. O IS0 2000 -All rights reserved 5 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards
46、 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or networking permitted without license from IHS -,-,- STDeISO 7481-ENGL 2000 4853903 08152b9 574 IS0 7481 :2000(E) Remove the assembly from the tensile machine. Remove the nut, then submit it to a visual examination, and if necess
47、ary, an examination at a magnification of xl O after sectioning to check conformity with the requirements of the procurement specification. Nuts subjected to this test shall not be used again. 3.4 Wrenching feature test This test applies only to wrenchable nuts. 3.4.1 Test device The test device is
48、illustrated in Figure 4. The test device includes the following elements: a) a block of steel, heat-treated to a hardness of 40 HRC; b) a bolt with characteristics as follows: 1) 2) 3) threads: in accordance with IS0 5855-2, tensile strength class: no specific requirement, material and coating: no specific requirement. NOTE For instance: - - Any other device which prevents the rotation of the nut and allows the specified torque to be applied is acceptable. nut welded on a block of the same material, the assembly being heat-