1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.QUESTIONS REGARDING THIS DOCUMENT: (412) 772-8512 FAX: (412) 776-0243TO PLACE A DOCUMENT
3、 ORDER; (412) 776-4970 FAX: (412) 776-0790Copyright 1997 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001RECOMMENDEDPRACTICESubmitted for recognition as an American National StandardJ1619ISSUEDJAN97Issued 1997-
4、01SINGLE TOOTH GEAR BENDING FATIGUE TEST1. ScopeThis SAE Recommended Practice defines the set-up and procedure for conducting the SAE SingleTooth Bending Fatigue Test. The details of the test fixture to be used (referred henceforth as “the test fixture”in this document) and gear test sample and the
5、procedures for testing and analyzing the data are presented inthis document.1.1 PurposeThe objective of this document is to provide a means to evaluate the effects of material andprocess variables on the bending fatigue behavior of gears using the test fixture. The bending fatigue life ofgear teeth
6、is generally influenced by variations in such factors as geometry, material, microstructure, residualstress profile, surface finish, case depth, surface and core hardness.This test serves as a screening tool to evaluate changes in one or more of these variables to enableoptimization of the processin
7、g and design of gears.2. References2.1 Applicable PublicationsThe following publications form a part of this specification to the extent specifiedherein. Unless otherwise specified, the latest issue of SAE publications shall apply.2.1.1 SAE PUBLICATIONAvailable from SAE, 400 Commonwealth Drive, Warr
8、endale, PA 15096-0001.SAE J821042Gear Single Tooth Bending Fatigue Test2.1.2 ASTM PUBLICATIONAvailable from ASTM, 100 Barr Harbor Road, West Conshohocken, PA STP-91Staircase Method for Fatigue Experiments2.1.3 AGMA PUBLICATIONAvailable from American Gear Manufacturers Association, 1500 King Street,
9、Suite201, Alexandria VA 22314-2730.AGMA 2001-B88908-B89 Fundamental Ratio Factors and Calculation Methods for Involute Spur and HelicalGear Teeth2.1.4 OTHER PUBLICATIONStatistical Design and Analysis of Engineering Experiments, Lipson and Sheth, “Fatigue Experiments,” pp.262-275.Copyright SAE Intern
10、ational Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-2-3. Test SpecimenThe test uses a specific gear as a test specimen to account for the complex nature ofbending and residual stress in a gear after pro
11、cessing and during loading. A straight cut 6-pitch, 34-tooth, 20-degree pressure angle spur gear with no tip relief is the recommended test sample (Figures 1A and 1B). Othertooth sizes and profiles are acceptable, depending on specific objectives of the test.4. Test Fixture4.1 The test fixture desig
12、n was evaluated and selected by the SAE ISTC Division 33 Gear Metallurgy Committeeand validated by a round robin gear test program. The results of the test machine validation are reported inSAE Publication 821042 (Reference 2.1.1) using a carburized and shot peened SAE 8620 steel gear. Figures2 and
13、3 shown the overall views of the fixture set-up. Figures 4 through 13 show the detail drawings of thecomponents of the test fixture. The fixture consists of a base (Figure 4), an upper load anvil (Figure 5), a lowersupport anvil (Figure 6), and a mandrel or mounting shaft (Figure 7). The fixture is
14、adaptable to a variety ofhydraulic cyclic testing machines when positioned between the load platens, provided the load is applied to thespherical seat located in the top anvil (Figures 2 and 3).4.2 The replaceable upper anvil insert (Figure 8) (not crowned) loads the test gear at the tooth tip. The
15、replaceablelower anvil insert (Figure 9) (not crowned) resists the load applied through the upper anvil and prevents samplerotation by contacting a support tooth near the base circle. The upper anvil (Figure 5) is mounted on theloading arm (Figure 10) as shown in Figure 11. The fixture base, load an
16、vil and support anvil are aligned by acommon shaft (Figure 7). The test gear is mounted on the shaft supported by roller bearings at the ends. Thebearing supports are shown in Figure 13. The gear and load anvil rotate in an arc about the gear axis, keepinga single line of contact across the gear too
17、th during loading. Load is applied to the fixture through a large ballbearing (Figures 2 and 3) to eliminate misalignment and to keep applied force in line with the loading andsupport anvils. The complete test assembly is shown in Figure 13.5. Test Procedure5.1 Gear PreparationOne gear tooth must be
18、 removed prior to testing the gear to provide clearance for thesupport anvil in the tooth root. This is accomplished by carefully grinding away one tooth (Figure 3) taking carenot to heat the gear above the tempering temperature. An alternate method is to remove the tooth prior to heattreatment.5.2
19、Fixture CalibrationIt is recommended that one test gear be strain gaged and used to periodically verify theconsistency of the test fixture. Wear on the anvil and shaft surfaces will change the loading on the gear toothand subsequently the root stress. A procedure for preparing a calibration gear usi
20、ng contact strain gages isgiven in Appendix A. All components are replaceable items. The recommended calibration procedure isestimated to provide a strain measurement precision of 10%.5.3 Test AssemblyThe test gear is first mounted on the shaft, then the support anvil is placed against one toothroot
21、 to prevent the gear from rotating. The load anvil is mounted on the same shaft as the gear and rotates inan arc around the gear axis. The load anvil contacts a tooth at the end of the active profile across the entireface of the tooth. Care must be taken to avoid corner loading or uneven contract ac
22、ross the face of the testtooth. Figure 13 shows the support anvil contacting the tooth in the root and the load anvil contacting thetested tooth at the tip. This ensures that a tensile bending stress is applied to the root of the test tooth.Support teeth are not used as tip loaded fatigue test speci
23、mens in subsequent tests. Suggested tooth loadingscheme is shown in the gear depicted in Figure 14.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-3-FIGURE 1ASPUR GEAR TEST SPECI
24、MENCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-4-FIGURE 1BNORMAL RACK PROFILECopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction o
25、r networking permitted without license from IHS-,-SAE J1619 Issued JAN97-5-FIGURE 2TEST FIXTURE ASSEMBLYFIGURE 3CLOSE-UP OF TEST GEAR SET-UPCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J1619 Iss
26、ued JAN97-6-FIGURE 4BASE PLATECopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-7-FIGURE 5UPPER ANVILCopyright SAE International Provided by IHS under license with SAENot for Resal
27、eNo reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-8-FIGURE 6LOWER ANVILCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-9-FIGURE 7MANDRELF
28、IGURE 8INSERT, UPPER ANVILCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-10-FIGURE 9INSERT, LOWER ANVILCopyright SAE International Provided by IHS under license with SAENot for
29、ResaleNo reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-11-FIGURE 10LOADING ARMCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-12-FIGURE 1
30、1ARM/ANVIL SUB-ASSEMBLYCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-13-FIGURE 12BEARING SUPPORTCopyright SAE International Provided by IHS under license with SAENot for Resale
31、No reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-14-FIGURE 13ASSEMBLYCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-15-FIGURE 14DIAGRAM
32、OF GEAR SHOWING USABLETEETH FOR TESTING5.4 LoadingWhen the load anvil is in contact with the tooth root, the test tooth is loaded by having the loadingdevice make contact through the spherical seat located in the upper load anvil (see Figure 5). Single toothbending fatigue tests are conducted using
33、a constant amplitude cyclic load of 20 to 30 Hz.5.5 TestingA cyclic load pattern with a minimum load magnitude of 10% of the maximum load (R = minimumload/maximum load = 0.1) is recommended to keep the load anvil in contact with the test tooth and avoid shockloading. Gear teeth are tested until comp
34、lete tooth fracture is achieved and the load and cycles to fracture arerecorded for each tooth. The base of the test fixture is operated on a film of oil to eliminate the transfer of sideloads into the tooth and loading device.5.6 Analysis of ResultsThe S-N (Stress versus Cycles) curve is composed o
35、f two lines. The finite part of theplot is determined by testing at a minimum of three distinct stress levels. The endurance limit or infinite part ofthe curve is determined using the Stair Case method described in ASTM STP-91 (Reference 2.1.2). The twocurves meet at a point commonly called the “kne
36、e.” A method for determining the range of endurance limitsbased on statistical methods is described in Statistical Design and Analysis of Engineering Experiments,Lipson and Sheth, “Fatigue Experiments,” pp. 262-275 (Reference 2.1.4). The test provides a guideline for theselection of loads in the fin
37、ite portion of the curve. A life of 10 million cycles will determine a run-out; anyshorter life is a failure. Appendix B provides further details of testing scheme and analysis.5.7 Gear Stress EstimationFormulas to calculate the bending stress in the roots of gear teeth are given inAGMA 2001-B88 and
38、 908-B89 (Reference 2.1.3). The load angle of the test fixture is used to calculate thebending stress in gears. To enable a reliable comparison of results between tests on a given gear geometry,some formulas must be applied consistently for stress calculations.Copyright SAE International Provided by
39、 IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-16-6. ReportReport results in the form of an endurance curve of stress versus log number of cycles to failure in asemi-log plot with the log cycles to failure on the X-a
40、xis. Important parameters to be reported along with thetest results are:a. Gear MaterialSteel grade, chemistry, cleanlinessb. Case DepthSurface carbon if applicablec. Carbon gradient and surface carbond. Case and Core Hardness DataHardness gradiente. Grain Sizef. MicrostructuralPercent retained aust
41、enite, presence of any oxidesg. Calibration Datah. Finishing method after heat treatment (e.g., shot-peening characterization, details, and grindingprocess as applicable)i. Residual stress profile as applicablePREPARED BY SAE IRON AND STEEL TECHNICAL COMMITTEE DIVISION 33GEAR METALLURGYCopyright SAE
42、 International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J1619 Issued JAN97-17-APPENDIX ASTRAIN GAGINGA.1 Strain GagesConstantan foil alloy, polyamide-backed, self-temperature-compensated strain gages with anactive grid
43、 length of 0.38 mm (0.015 in) are recommended. Gage resistance is 120 W with a gage factorsetting of 2.13 for direct read-out. The gage configuration is a vertical grid with side solder tabs and four 90degree alignment arrows. A.2 Strain Gage PlacementA metal template, shown in Figure A1, having fiv
44、e scribed lines is used to locatethree strain gages at the point of maximum bending stress that is determined by the distance (X) from the toothtip of the fracture line of a broken tooth. Transparent adhesive tape peeled from the tooth is used to transferthe reference distance (X) from a broken toot
45、h involute surface. Parallel lines (a and b) are scribed on thetemplate and are separated by a distance equal to (X). A centerline is scribed at the center of the tooth widthand perpendicular to line b. Two lines such that they are equidistant from the line of the center of the width arescribed perp
46、endicular to line (b) or along with width.FIGURE A1A BROKEN TOOTH AND THE METAL TEMPLATE WITH LINES TO LOCATETWO STRAIN GAGES ALONG THE WIDTH OF THE TOOTH AT EQUALDISTANCES FROM THE THIRD ONE AT THE CENTERA.2.1 Alignment arrows on the strain gage backing are used to position each gage over the cross
47、ed lines on thetemplate with the aid of a stereobinocular at 25X magnification. Transparent, pressure-sensitive, double facedtape is laid over the gages on the template so that the straight edge of the tape lays on line (a). The tape isrolled on top of the gages being careful not to disturb the alig
48、nment. In the case of the test gear used fordevelopment of the test, the distance was 10.2 mm.A.2.2 A molded rubber replica of the cavity between adjacity gear teeth is prepared to position the gages in the toothroot. First, a cavity is formed by bridging the end faces of two adjacent teeth with masking tape. Then siliconerubber is poured into the cavity and to a level that covers the tips of the adjacent gear teeth (Figure A2). Therubber replica is removed from the cavity and inverted. The assembly of three strain gages positioned on thetemplate is then transfer
