1、December 2005DEUTSCHE NORM English price group 7No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 21.060.30!$IVL“1385
2、141www.din.deDDIN 267-26Technical delivery conditions for fasteners Part 26: Conical spring washers for bolt/nut assembliesMechanische Verbindungselemente Technische Lieferbedingungen Teil 26: Spannscheiben aus Federstahl fr SchraubenverbindungenSupersedesDIN 267-26:1987-10www.beuth.deIn case of dou
3、bt, the German-language original should be consulted as the authoritative text.Translation by DIN-Sprachendienst.Document comprises 10 pagesDIN 267-26:2005-12 2 Foreword This standard has been prepared by the Normenausschuss Mechanische Verbindungselemente (Fasteners Standards Committee), Technical
4、Committee NA 067-04-02 AA Scheiben und Ringe. The DIN 267 standards series consists of the following parts, under the general title Technical delivery conditions for fasteners: Part 2: Design and dimensional accuracy Part 6: Design and tolerances for product grade F fasteners Part 13: Parts for bolt
5、/nut assemblies with specific mechanical properties for use at temperatures ranging from 200 C to +700 C Part 24: Hardness classes for nuts Part 26: Conical spring washers for bolt/nut assemblies Part 27: Adhesive-coated steel screws, bolts and studs Part 28: Self-locking steel screws, bolts and stu
6、ds Part 29: Product grades for parts for bolt/nut assemblies for use at temperatures ranging from 200 C to +700 C Part 30: Metric thread rolling screws of property class 10.9 Amendments This standard differs from DIN 267-26:1987-10 as follows: a) The title has been amended. b) The standard now only
7、covers conical spring washers. c) References have been updated. d) In order to reduce the risk of hydrogen embrittlement, a maximum hardness of 490 HV has been specified. e) For conical spring washers intended for use with screw and washer assemblies, the minimum free height has been corrected in ac
8、cordance with DIN 6908:1995-08. f) The compression load for spring force testing has been increased. g) The residual spring force values are no longer given as provisional specifications. h) A normative Annex A giving a detailed description of the test device for the spring force test has been added
9、. i) A normative Annex B on the determination of the spring characteristic curve has been included. Previous editions DIN 267-26: 1987-10 DIN 267-26:2005-12 3 1 Scope This standard specifies requirements and methods of test for conical spring washers which are intended for use with bolt/nut assembli
10、es as dealt with in the following standards: DIN 6796, Conical spring washers for bolt/nut assemblies DIN 6908, Conical spring washers for screw and washer assemblies It is recommended that this standard also be applied for conical spring washers for bolt/nut assemblies which have not been standardi
11、zed. Conical spring washers made from materials other than spring steel are not covered by this standard. NOTE Conical spring washers serve to counteract the loss in inherent tension caused by setting and creep of a bolt/nut assembly provided that they are sufficiently resilient to increase the over
12、all resilience of the assembly; their inherent spring force can compensate for any loss in tension so that the clamping force required to ensure the reliability of the assembly is maintained. There may be relative movement between bolt and nut if the friction between the clamped components is overco
13、me by transverse forces. If this does occur, loosening of the assembly cannot usually be prevented by spring washers. Thus, when using these components, it should be checked whether the spring washers may usefully be employed as the elements maintaining the clamping force. 2 Normative references The
14、 following reference documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. DIN 879-1, Precision dial indicators Part 1: Analogue
15、 indicators DIN 6796, Conical spring washers for bolt/nut assemblies DIN 6908, Conical spring washers for screw and washer assemblies DIN EN 10089, Hot rolled steels for quenched and tempered springs Technical delivery conditions DIN EN 10132-4, Cold-rolled narrow steel strip for heat-treatment Tech
16、nical delivery conditions Part 4: Spring steels and other applications DIN EN ISO 3269, Fasteners Acceptance inspection DIN EN ISO 4042, Fasteners Electroplated coatings DIN EN ISO 6507-1, Metallic materials Vickers hardness test Part 1: Test method DIN EN ISO 6508-1, Metallic materials Rockwell har
17、dness test Part 1: Test method (scales A, B, C, D, E, F, G, H, K, N, T) DIN EN ISO 18265, Metallic materials Conversion of hardness values DIN 267-26:2005-12 4 VDI 2230-1:2003, Systematic calculation of high duty bolted joints Joints with one cylindrical bolt 3 General requirements The effectiveness
18、 of springs washers in bolt/nut assemblies depends on the material (see clause 4) and whether the test criteria specified in clause 5 are met. Spring washers shall have a smooth surface and be free from scale and burrs. The surface roughness shall be specified in the relevant product standards where
19、 required. In the as-delivered condition, spring washers shall have rust protection. DIN EN ISO 4042 shall apply with regard to electroplating. NOTE Hydrogen-induced embrittlement cannot be ruled out when employing current methods of applying metal coating from aqueous solutions (see DIN EN ISO 4042
20、). As there is even an increased risk of embrittlement in the case of components with a hardness of 400 HV, particular care is to be taken when selecting the material, and in connection with heat treatment and surface treatment. 4 Material Spring washers shall be made of spring steel (FSt) complying
21、 with DIN EN 10089 or DIN EN 10132-4, or of spring steel with equivalent properties, the grade being at the manufacturers discretion. This requirement shall also apply where the documentation does not specify any material. Spring washers for bolt/nut assemblies, in the hardened and tempered conditio
22、n, shall have a hardness of 420 HV to 490 HV. 5 Testing 5.1 Testing for dimensional stability and finish The specifications of DIN EN ISO 3269 shall apply for acceptance inspection with respect to the dimensional stability of spring washers. For the characteristics internal diameter, washer thicknes
23、s, free height and external diameter, an AQL value of 1,5 shall apply. 5.2 Testing the mechanical properties 5.2.1 General The mechanical properties shall be tested as specified in 5.2.2 to 5.2.5. DIN 267-26:2005-12 5 5.2.2 Hardness testing DIN EN ISO 6507-1 shall apply for the Vickers hardness test
24、. DIN EN ISO 6508-1 shall apply for the Rockwell hardness test. DIN EN ISO 18265 shall apply for the conversion of hardness values. When testing conical spring washers, the value shall be measured, where possible, in the middle of the washer surface. The supporting surface on which the measurement i
25、s made shall be firm. 5.2.3 Test for permanent set The spring washers to be tested shall be compressed for two minutes using the compression loads specified in Table 1. NOTE The compression loads correspond to the preloads for bolts of property class 8.8, with G= 0,12 in accordance with VDI 2230-1:2
26、003. The free height of the washers (height after release of pressure) shall not be less than the values specified in Table 1. 5.2.4 Permanent load test Ten conical spring washers, threaded with alternating orientation on a bolt and separated from one another by parallel-faced washers (hardened to a
27、t least 500 HV), shall not fracture after 48 hours conditioning at a temperature of +100 C under the compression loads specified in Table 1, nor shall the free height be more than 2 % below the values specified in Table 1. DIN 267-26:2005-12 6 Table 1 Test for permanent set Nominal size (bolt thread
28、 size) 2 2,5 3 3,5 4 5 6 Compression loadakN 0,92 1,54 2,35 3,16 4,4 7,2 10,2 DIN 6796 0,5 0,6 0,7 0,9 1,1 1,3 1,7 Minimum free height mm DIN 6908b 0,61 0,72 0,92 1,12 1,35 1,70 Nominal size (bolt thread size) 7 8 10 12 14 16 18 Compression loadakN 14,8 18,6 29,6 43 59,1 80,9 102 DIN 6796 2 2,2 2,8
29、3,4 4 4,6 5,1 Minimum free height mm DIN 6908b 2,24 2,8 3,43 Nominal size (bolt thread size) 20 22 24 27 30 Compression loadakN 130 162 188 246 300 DIN 6796 5,6 6,1 6,8 7,3 8 Minimum free height mm DIN 6908b aCorresponds to the preload for bolts of property class 8.8, with G= 0,12 in accordance with
30、 VDI 2230-1. bAs a deviation from the specifications given in the relevant product standard for washers for screw assemblies, the bolt thread size instead of the inside diameter shall be used as the relevant nominal size. 5.2.5 Spring force test In order to assess the resilience of spring washers, a
31、 spring force test shall be carried out. This test permits the residual spring force to be determined. The washer to be tested shall be placed in the test device and subjected to the compression load specified in Table 2. The test device shall be designed to permit as uniform an application of the l
32、oad as possible. The pressure platen shall have a minimum surface hardness of 60 HRC. After two minutes, the load applied to the spring washer shall be slowly and steadily released through a travel of 20 m, which shall be measured using a precision measuring device. The residual spring force after r
33、elease through a travel of 20 m shall reach the values specified in Table 2, due allowance being made for any deformation of the test device. A suitable test device is described in Annex A. Specifications for determining the spring characteristics are given in Annex B. Table 3 summarizes the residua
34、l spring forces required for all washer types. DIN 267-26:2005-12 7 Table 2 Minimum residual spring forces Nominal sizea4 5 6 7 8 10 12 14 16 Compression loadbkN 4,4 7,2 10,2 14,8 18,6 29,6 43 59,1 80,9 Minimum residual spring force kN 1,4 2,3 4,2 6,2 7,7 12,4 18 25 34 Nominal sizea18 20 22 24 27 30
35、 Compression loadbkN 102 130 162 188 246 300 Minimum residual spring force kN 57 73 91 122 161 196 aAs a deviation from the specifications given in DIN 6908 for washers for screw assemblies, the bolt thread size instead of the inside diameter shall be used as the relevant nominal size. bCorresponds
36、to the preload for bolts of property class 8.8, with G= 0,12 in accordance with VDI 2230-1. Table 3 Residual spring forces (overview) Type of washer As specified in Compression load corresponding to the preload for property class Residual spring force after release through travel of 20 m, as a perce
37、ntage of the compression load Conical spring washer DIN 6796 DIN 6908 8.8 35 % for nominal sizes 4 to 5 45 % for nominal sizes 6 to 16 60 % for nominal sizes 18 to 22 70 % for nominal sizes above 22 6 Form of supply Conical spring washers shall be packed to give adequate protection against mechanica
38、l damage during transport. The packages shall be marked with the standard designation specified in the relevant product standard, e.g.: DIN 6796 8 FSt In addition, the number of units in the package and the manufacturers symbol shall be stated on the package. DIN 267-26:2005-12 8 Annex A (normative)
39、 Test device for the spring force test A.1 General Figure A.1 shows an example of a suitable test device. Other designs may be used, provided the requirements specified in A.2 are met. Key 1 Pressure platen 5 Centring device 2 Bearing plate 6 Pedestal 3 Centring pins 7 Sleeve 4 Measuring pin 8 Trave
40、l gauge Figure A.1 Example of a test device DIN 267-26:2005-12 9 A.2 Requirements for the test device a) Low resilience and, if possible, only (elastic) compressive deformation without flexural deformation of the complete test device, in particular in the zone where the force is transmitted from the
41、 pressure platen (1) to the bearing plate (2) and the upper part of the pedestal (6). b) Centric bore in the pedestal permitting the passage of the measuring pin (4) of the travel gauge (8) and that of the sleeve (7). c) Fastening of travel gauge (8) using a sleeve (7) at exactly the same height as
42、the upper face of the bearing plate (2), so as to ensure that the error resulting from the inherent deformation of the gauge is as small as possible. d) Bearing plate (2) and sleeve (7) removable, so that bearing plates for different washer diameters can be used. e) All surfaces via which the force
43、is applied and the elastic deformations of which are included in the travel measurements shall have a roughness Ra 0,4 (corresponding to Rz 1,6). f) The bearing plate (2) and the pressure platen (1) shall have a hardness 60 HRC. g) The pressure platen (1) shall be guided so as to be parallel to the
44、bearing plate, a useful feature being a play of some tenths of a millimetre in the plane of the bearing plate to compensate for low elastic forces (this is generally provided for in universal testing machines). h) The compression load shall be adjustable to within 2 %, and it shall be possible to re
45、ad the residual spring force to within 2 %. i) The dial indicator, the inductive travel gauge or any other travel gauge (8) used may only have a relative repeatability error and reversibility error not exceeding 1 m for any partial measuring range of 40 m, the direction of movement of the measuring
46、pin being away from the gauge (see DIN 879-1 for definitions). DIN 267-26:2005-12 10 Annex B (normative) Determination of spring characteristic curve When determining the spring characteristic of spring washers as part of the spring force test, the effect of the elastic deformation of the test devic
47、e is to be allowed for by deducting the spring travel originating in the test device from the overall travel (i.e. that of spring washer and test device). The relief characteristic curve for the test device is to be determined as follows. Instead of a spring washer, a plain washer shall be placed in
48、 the test device (see Figure A.1 for example). The plain washer shall be lapped on both sides and have a tolerance on parallelism 1 m and a hardness 700 HV. The washer dimensions (inside diameter, outside diameter and thickness) shall be identical to those of the spring washer to be tested. The reli
49、ef characteristic curve of the test device, starting at the compression loads specified in Table 2, shall be plotted. NOTE It is essential that parallel-faced washers having the same dimensions as the spring washers to be tested be used when recording the relief characteristic curve of the test device, as different-sized washers will give different characteristics. In Figure B.1, the continuous line represents the total relief characteristic curve (conical spring washer
