PROF. DR.-ING. MAX KLÖCKER                                           ALTE VAALSER STRASSE 147LEHRGEBIET ANTRIEBS- UND F......
1           General1.1 Automatic release: mechanisms of loosening and unwindingThe function of the bolt connection is to c...
•   loss prevention devices with clamping elements. These are usually only effective if the bolted    connection is alread...
Figure 2: Principal test sequence during the vibration test: preload force (1), shear force (2) and          transverse di...
4 Experimental parameters and experimental procedureWith the client, HEICO Befestigungstechnik GmbH, the following were se...
4.6 Preload force and torqueThe test bolts were tightened with a special torque wrench. The following preloads were tighte...
4.8 Test frequencyAccording to DIN 65151 the frequency of the transverse displacement is set at 12.5 Hz.5     Test finding...
Quellennachweis/1/ Ilgner, K.H.; Esser, J.: Schraubenvademecum 9. Auflage, Textron Verbindungstechnik GmbH&CoOHG Neuwied, ...
FM-04-PM                                                   FormEd 1 Rev 0Page 9 of 9                               Certifi...
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HEICO-LOCK Junkers Test Report English

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HEICO-LOCK Junkers Test Report English

  1. 1. PROF. DR.-ING. MAX KLÖCKER ALTE VAALSER STRASSE 147LEHRGEBIET ANTRIEBS- UND F...RDERTECHNIK SOWIE 52074 AACHENSTAHLBAU EINSCHL. STRUKTURANALYSE TEL. 0241/85282AN DER FACHHOCHSCHULE K...LN Expert Opinion Assessment of the Safety Behaviour of Wedge Locking Washer Pair Nominal Size 8 19.04.2010 Client HEICO Befestigungstechnik GmbH Ensestraße 1-9 59469 EnseContents1. Ge nera l 1.1 Automatic release: mechanisms of loosening and unwinding 1.2 Safety measures: state of the technology2. Reason and purpose of the examinations3. Vibration test to examine the effect of the Wedge locking washer pairs4. Experimental parameters and experimental procedure 4..1 Variants examined and their installation in the test 4.2 Strength class and hardening 4.3 Surface 4.4 Lubrication 4.5 Clamping length 4.6 Preload force and torque 4.7 Experimental setting and determination of transverse displacement 4.8 Test frequency5. Test findings and Conclusions6. SourcesThis expert opinion consists of 8 pages. Page 1 of 9
  2. 2. 1 General1.1 Automatic release: mechanisms of loosening and unwindingThe function of the bolt connection is to connect parts in the assembly with the preload force applied andtransferred to the operating forces.The loosening of threaded connections is generally characterised by loss of clamp load /1/.Differentiating loosening and unwinding.With predominantly axial loading bolt loosening occurs due to plastic deformation caused by settlingand creep phenomena. With a normal bolt connection designed with high tension and long clampinglength, these plastic deformations can be sufficiently compensated for so that no loosening is expected/2/.The mechanisms of unwinding typically occur at angles in dynamically loaded bolted connections. Themain reason for this is that when acting perpendicularly to the bolt axis, the dynamic lateral loaddecreases the friction between the components and is eventually eliminated. One result is slippage in thecontact zones. Thus, relative movement in the joints between the components is possible in the head andbetween the thread edges of the bolt and nut. The lateral stiffness affects the individual parts of thethreaded connection.According to Blume, the elastic bending deformation of the threaded shaft with forced transversedisplacements of the clamped components has a significant impact on the unwinding of the bolt /3/. Thefailure limit is defined by the boundary shift. It depends upon the elasticity of the bolt and the transferability ofthe lateral forces on the head or nut through friction. According to Blume the structural mechanicsequivalence model is inadequate to capture the real deformation mechanisms. In the determination of thetheoretical movement limit in the unwinding from a theoretical point of view, it originates exclusively from theS-shaped deformation of the threaded shaft and the expected friction on the bearing surfaces of the threadedcomponents. Due to other practical factors, however, it is not suitable for a mathematical proof of unwindingsafety /4/. The designer therefore must depend upon experience, recommendations in standards andexperimental testing.In the vibration test to assess the safety measures against unwinding, a reference standard must first beestablished by implementing an experimental setting to eliminate the influence of testing stand stiffness on thetest results: on the vibration testing stand according to DIN 65151 /5/, the transverse displacement in theclamped state is determined as when the pre-load force for an uncoated bolt has fallen to zero after aspecified number of cycles (300 LW). This transverse displacement is then compared with studies basedon safety measures.This approach will be defined in a future supplement to DIN 25201-4 /6/.1.2 Safety measures (state of the technology)A diagram of the loosening mechanism as well as of the safety mechanism to prevent loosening issummarised in DIN 25201-4: ”Securing threaded connections” (in Table A1) /6/. The standard contains asummary in table form of safety elements and their function types and provides instruction on their application.The standard DIN 25201-4 basically differentiates:· unwinding safety to reduce the contact pressure due to increased contact surfaces and to compensate for the expected amounts from the suspension of the locking washer. The effective use of these safety elements requires a detailed knowledge of the elasticities of the individual fasteners.· security nut with locking or adhesive functional elements. Locking elements require sufficient slippage security elements between the safety nuts and the bearing surfaces of the bolt or nut and the components. The necessary material is shown on page 3 of 3 and is achieved by an appropriate design of the locking washer and through various hardnesses. Page 2 of 9
  3. 3. • loss prevention devices with clamping elements. These are usually only effective if the bolted connection is already inoperative. By an increase in the friction of the bolt they cause an increase in unwinding torque and should before be given an additional preload force. In addition, these elements prevent a final separation.The Wedge locking washer pairs under examination are set out in Table A1 of DIN 25201-4:“Construction guidelines for rail vehicles and their components – Bolt connections – Safety of boltconnections” /6/ in the Security nuts with locking elements category.2 Reason and purpose of the examinationsThe aim of the examination was to assess the safety behaviour of the Wedge locking washer pairs incomparison with the unsecured bolt connections by vibration tests on a test device in accordance withDIN 65151.3 Vibration test to examine the effect of the safety elementsTo examine the effectiveness of safety elements, the testing device is used in accordance with DIN 65151/5/. This consists of transversely moving slides which are clamped together over the bolt and nut to be tested.Between the slides, a roller guide is arranged to stop the friction between the clamped parts and toconcentrate on the examination of the unwinding process of the bolt. The transverse displacement ofthe slides comes from an adjustable eccentric drive mechanism (Figure 1).Figure 1: Principal test design and recognised measured variablesThe locking washers to be assessed are compared with the unsecured bolt connection. For this, in anexperimental setting of the bolt connections which are unsecured and otherwise comparable in all testparameters in the clamped state, the transverse displacement is determined by the unwound bolt after 300load cycles (preload force = 0 N). This transverse displacement is maintained for the examination of thelocking washers, so that the safety or torque retaining bolt is directly comparable with the unsecured set-up. The running time of an unwinding process described in terms of measured variables (clamp load,lateral displacement, shear force, number of cycles) is shown as an example in Figure 2. The failurecriterion used for the test is the preload torque loss that is detected as a function of cycle load changes.Furthermore, during the experimental procedure the initiated lateral force and lateral displacementcontinued to be measured.This testing and the test parameters were developed and verified within the framework of an industriallysponsored research contract from the University of Applied Science in Cologne and IMA MaterialsResearch and Application in Dresden /7/. It will be presented in a future supplement to DIN 25201-4 / 6 /. Page 3 of 9
  4. 4. Figure 2: Principal test sequence during the vibration test: preload force (1), shear force (2) and transverse displacement (3)With respect to the current practice /7/ was agreed with the clientRuns: residual preload force after 2000 load cycles greater than 80% of the preload assembly. For quantitative comparison of the runs the percentage of the residual clamp load at 2000 LC cycles is identified and put into the resultsFailure: residual preload force after 2000 load cycles less than 80% of the preload assembly. For quantitative comparison of the failure, the number of cycles where the 80% criterion is exceeded is determined and placed against the summary of the results. Page 4 of 9
  5. 5. 4 Experimental parameters and experimental procedureWith the client, HEICO Befestigungstechnik GmbH, the following were set up for the vibration tests:4.1 Variants examined and their installation in the test · Experimental settings with unsecured bolts (3 to 5 times) · Tests with the bolts secured by narrow wedge locking washer pairs M8x2.5 12 tests to determine the reproducibility.Mounting position in the test: the test bolt with the wedge locking washer pair to be assessed wasinserted into the top of the slide and driven by an eccentric top slide. It protruded through the bolt hole ofthe fixed lower slide and was secured there with similarly torsioned nuts (strength class, surface). The Wedgelocking washer pair was placed on a torsion washer ISO 7093 -1 (hardness class 200 HV). Nut and washerwere replaced for each test.4.2 Strength classes and hardeningThe bolts were marked with 8.8 and GFD, the nuts with 8.In accordance with the strength class of the nuts the washers DIN 7093-1 had the required hardness200HV.4.3 SurfaceThe bolt parts were each coated with · flZnnc 480h-L(label on package)The wedge locking washer pairs were coated as follows: · “Narrow” washer geometry: Delta Protect (KL100)The washers DIN 7093-1 were ground flat and polished.4.4 LubricationThe head-bearing surfaces and threads of the test samples were lubricated with molybdenum sulphite.4.5 Clamping LengthThe clamping length (distance between the contact surfaces in the test) was 17 x the nominal diameter. Page 5 of 9
  6. 6. 4.6 Preload force and torqueThe test bolts were tightened with a special torque wrench. The following preloads were tightened:M8: 9.1 kNThese values correspond to the 80% preload force according to VDI 2230, based on 90% utilisation ofthe yield point, if strength class is defined as 10.9 (according to FK10 of the nuts tested) and the friction is0.14. The corresponding torque was metrologically recorded and measured using the special key.Table 2 in accordance with ZEV-Rail Glasers Annalen 132, May 2008/7/.The preload strengths given in the table represent 50% of the values provided in VDI 2230 [8]. Unit M8 M10 M12 M 16 M20 M24 M30 M36 2 2 8.8 RP0,2 = 640 N/mm RP0,2 = 660 N/mm vRp0,2 = 1,0 kN 20.1 32.0 46.6 87.7 141 203 325 475 a) 50% kN 9.1 14.4 21.0 39.5 64 92 146 214 75% a) kN 13.6 21.6 31.5 59.2 95 137 219 320 100%a) kN 18.1 28.8 42.0 78.9 127 183 292 427 2 10.9 RP0,2 = 940 N/mm vRp0,2 = 1,0 kN 29.6 47.0 68,5 128.8 201 290 463 676 50% a) kN 13.3 21.2 30,8 58.0 91 130 208 304 75% a) kN 20.0 31.7 46,2 86.9 136 196 312 456 100% a) kN 26.6 42.3 61.7 115.9 181 261 417 609 2 A2-70 RP0,2 = 450 N/mm vRp0,2 = 1,0 kN 14.2 22.5 32.8 61.7 96.3 These thread sizes 50% a) kN 6.4 10.1 14.8 27.7 43.4 Are not available 75%a) kN 9.6 15.2 22.1 41.6 65.0 on the market! 100% a) kN 12.7 20.3 29.5 55.5 86.7 A4-80 RP0,2 = 600 N/mm2 vRp0,2 = 1,0 kN 18.9 30.0 43.7 82.2 128.5 These thread sizes 50% a) kN 8.5 13.5 19.7 37.0 57.8 Are not available 75% a) kN 12.7 20.3 29.5 55.5 86.7 on the market! 100% a) kN 17.0 27.0 39.4 74.0 115.6 Ripp RP0,2 = 940 N/mm2 vzul = 1,0 b) kN 23.2 37.0 54.0 102,0 50% c) kN 11.6 18.5 27.0 51,0 These thread sizes are not 75% c) kN 17.4 27.8 40.5 76,5 available on the market! il bl 100% c) kN 23.2 37.0 54.0 102,0a) Percentage refers to an allowable yield point utilisation Rp 0.2 of 90%b) Permitted preload force according to Acument company documentc) Percentage refers to an Acument company document4.7 Experimental setting and determination of transverse displacementIn all attempts transverse displacement setting for all tests were determined by experimental settings onthe unsecured bolts with the preload forces shown in section 4.6.In the cross-braced setting there were the following transverse displacements: M8 +/- 0,06 mm +/- (0,098 mm non-stressed). Page 6 of 9
  7. 7. 4.8 Test frequencyAccording to DIN 65151 the frequency of the transverse displacement is set at 12.5 Hz.5 Test findings and conclusionsThe safety behaviour of the wedge locking washer pairs under examination can be clearly seen in thefollowing table.M8-8.8, “Narrow” disc geometry Load Rest-FV at Rest -FV at FV 80% F V change 2000 LW 2000 LW Test number [kN] [kN] of [kN] [%] KVO08_100415_73-11-35-81_1-P1 8.98 7.18 > 2000 7.76 86.41 KVO08_100415_73-11-35-81_1-P2 9.08 7.26 > 2000 7.92 87.22 KVO08_100415_73-11-35-81_1-P3 9.08 7.26 > 2000 7.77 85.57 KVO08_100415_73-11-35-81_1-P4 9.03 7.22 > 2000 7.56 83.72 KVO08_100415_73-11-35-81_1-P5 8.98 7.18 > 2000 7.70 85.75 KVO08_100415_73-11-35-81_2-P1 9.08 7.26 > 2000 7.91 87.11 KVO08_100415_73-11-35-81_2-P2 9.03 7.22 > 2000 7.87 87.15 KVO08_100415_73-11-35-81_2-P3 9.20 7.36 > 2000 7.81 84.89 KVO08_100415_73-11-35-81_2-P4 9.08 7.26 > 2000 7.78 85.68 KVO08_100415_73-11-35-81_2-P5 8.94 7.15 > 2000 7.65 85.57 KVO08_100415_73-11-35-81_3-P1 9.03 7.22 > 2000 7.74 85.71 KVO08_100415_73-11-35-81_3-P1 9.08 7.26 > 2000 7.88 86.78Overall assessment:In the test conditions presented in Section 4, all the examined wedge locking washer pairs, withoutexception, showed a residual preload force of more than 80% of the assembly preload strengthafter 2000 load cycles.The locking effect of the examined wedge locking washer pairs, according to the quantitativetest result, was rated as fully effective.These tests were carried out with the greatest care and the expert opinion was formed in good faith andconscience. However errors cannot be ruled out.Fundamentally, the users of the results are not exempt from testing the usability of the described safetyelements in specific cases.Neither legal responsibility not liability can be accepted by the expert.(Prof. Dr. Eng. Max Klöcker) Page 7 of 9
  8. 8. Quellennachweis/1/ Ilgner, K.H.; Esser, J.: Schraubenvademecum 9. Auflage, Textron Verbindungstechnik GmbH&CoOHG Neuwied, Rasch Verlag 2001, ISBN 3-935326-46-7./2/ VDI 2230, Blatt1: Systematische Berechnung hochbeanspruchter Schraubenverbindungen. Oktober2001./3/ Blume, D.: Wann müssen Schraubenverbindungen gesichert werden? Verbindungstechnik 1(1969) Nr. 4, S. 25-30./4/ Klöcker, M.; Hufschmidt, K. Einflussgrößen auf das selbsttätige Losdrehen von Schraubenverbindungen und praxisgerechte Prüfung. DVM-Tagungsbericht Nr. 1644, Berlin 2004./5/ DIN 65151: Dynamische Prüfung des Sicherungsverhaltens von Schraubenverbindungen unterQuerbeanspruchung (Vibrationsprüfung). Februar 2002./6/ DIN 25201-4: Konstruktionsrichtlinie für Schienenfahrzeuge und deren Komponenten - Schraubenverbindungen– Teil 4: Sichern von Schraubenverbindungen. Juni 2004./7/ Franke, R.; Gärtner, E.; Klöcker, M.: Funktionssicherheit von Schraubenverbindungen mit Sicherungselementen für Schienenfahrzeuge Page 8 of 9
  9. 9. FM-04-PM FormEd 1 Rev 0Page 9 of 9 Certificate of accuracy Lingo24 Ltd. 66 Queen’s Road ABERDEEN, AB 15 4YE roxana.telescu@lingo24.com 12th of July 2011 To whom it may concern I hereby certify that the attached English translation: Expert Opinion, Assessment of the Safety Behaviour of Wedge Locking Washer Pair Nominal Size 8 from 19.04.2010 is a true and correct translation of the attached German document, to the best of my knowledge and belief. Signed for and on behalf of Lingo24 Ltd, TELESCU ROXANA Account Manager Lingo24 Ltd Page 9 of 9

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