AGMA 937-A12-2012 Aerospace Bevel Gears.pdf

1、ANSI/AGMA 937-A12 AGMA 937-A12 AGMA Information Sheet Aerospace Bevel Gears AMERICAN GEAR MANUFACTURERS ASSOCIATION AGMA 937-A12 AGMA 2012 All rights reserved ii Aerospace Bevel Gears AGMA 937-A12 CAUTION NOTICE: AGMA technical publications are subject to constant improvement, revision or withdrawal

2、 as dictated by experience. Any person who refers to any AGMA Technical Publication should be sure that the publication is the latest available from the Association on the subject matter. Tables or other self-supporting sections may be referenced. Citations should read: See AGMA 937-A12, Aerospace B

3、evel Gears, published by the American Gear Manufacturers Association, 1001 N. Fairfax Street, Suite 500, Alexandria, Virginia 22314, http:/www.agma.org. Approved October 25, 2012 ABSTRACT This information sheet covers aerospace bevel gears for power, accessory and actuation applications. This inform

4、ation sheet provides additional information on the design, manufacturing and quality control unique to the aerospace environment. Published by American Gear Manufacturers Association 1001 N. Fairfax Street, Suite 500, Alexandria, Virginia 22314 Copyright 2012 by American Gear Manufacturers Associati

5、on All rights reserved. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior written permission of the publisher. Printed in the United States of America ISBN: 978-1-61481-030-8 American Gear Manufacturers Association AMERICAN GEAR

6、MANUFACTURERS ASSOCIATION AGMA 937-A12 AGMA 2012 All rights reserved iii Contents Foreword ix 1 Scope . 1 2 Normative references . 1 3 Symbols and definitions . 1 4 Application . 5 5 Types of bevel gears 5 5.1 Straight bevel gears 5 5.1.1 Coniflex gears . 5 5.2 Spiral bevel gears . 5 5.2.1 Circular

7、lengthwise tooth curvature system 8 5.2.2 Involute lengthwise tooth curvature system 8 5.2.3 Epicycloidal lengthwise tooth curvature system 8 5.2.4 Zerol bevel gears. 9 6 Design of aerospace bevel gears 9 6.1 Preliminary design considerations 9 6.1.1 Loading 9 6.1.2 Special operating considerations

8、10 6.1.3 Estimated pinion size 10 6.1.4 Material factor, CM. 11 6.1.5 Numbers of teeth . 12 6.1.6 Face width . 13 6.1.7 Diametral pitch 14 6.1.8 Spiral angle . 14 6.1.9 Pressure angle 15 6.1.10 Hand of spiral 16 6.1.11 Shaft angle 16 6.2 Tooth geometry and cutting considerations 16 6.2.1 Tooth taper

9、 16 6.2.2 Gear tooth design 17 6.2.3 Outer pitch diameter, d and D . 17 6.2.4 Pitch angle, and . 18 6.2.5 Mean cone distance, Am18 6.2.6 Mean working depth, h 18 6.2.7 Clearance, c 18 6.2.8 Mean addendum factor, c118 6.2.9 Sum of dedendum angles, . 19 6.2.10 Dedendum angles, Pand G19 6.2.11 Face ang

10、le of blank, 0and 020 6.2.12 Mean normal circular thickness, tnand Tn. 20 6.2.13 Outer normal backlash allowance, B . 20 6.2.14 Mean normal chordal thickness, tncand Tnc, and mean chordal addendum, acPand acG20 6.2.15 Straight, zerol and spiral bevel design formulas . 21 6.2.16 Undercut check . 23 6

11、.3 Blank considerations . 23 6.3.1 Shaft mounting 23 6.3.2 Tooth backing 23 6.3.3 Web design . 24 6.3.4 Cutter clearance 25 6.3.5 Splined bores 25 6.4 Tolerance requirements 25 6.4.1 Gear blank dimensions and tolerances . 25 AMERICAN GEAR MANUFACTURERS ASSOCIATION AGMA 937-A12 AGMA 2012 All rights r

12、eserved iv 6.4.2 Accuracies of tooth components . 25 6.4.3 AGMA accuracy grades 26 6.4.4 Tooth contact patterns 26 6.4.5 Backlash 26 6.4.6 Surface roughness influences . 27 6.4.7 Surface roughness selection . 27 6.4.8 Dynamic balance quality . 28 6.5 Gear mounting. 32 6.5.1 Bearing support . 32 6.5.

13、2 Spline shaft mounting 33 6.5.3 Bore and key mounting . 33 6.5.4 Gear deflections 33 6.6 Gear resonance. 34 6.6.1 Gear resonance determination by testing . 35 6.6.2 Gear resonance determination by finite element analysis 35 6.6.3 Gear redesign 35 6.6.4 Vibration damping . 36 7 Load capacity . 37 7.

14、1 Surface durability. 37 7.1.1 Permissible contact stress number . 37 7.2 Bending strength . 38 7.2.1 Permissible bending stress number 38 7.3 Modifying factors . 38 7.3.1 Load distribution 38 7.3.2 Overload factor, Ko41 7.3.3 Size factor, Cs, Ks41 7.3.4 Dynamic factor, Kv. 41 7.3.5 Stress cycle (li

15、fe) factor, CL, KL. 42 7.3.6 Temperature factor, KT42 7.3.7 Reliability, KR. 42 7.3.8 Pitting resistance hardness ratio factor, CH. 42 7.4 Other design criteria 42 7.4.1 Limit load . 42 7.4.2 Allowable limit stress . 42 7.4.3 Ultimate load . 43 7.4.4 Alternate approach 43 7.5 Crowning factor, Cxc43

16、7.6 Lengthwise curvature factor, Kx44 7.7 Scuffing . 44 7.7.1 Mechanisms of scuffing . 44 7.7.2 Degrees of scuffing . 44 7.7.3 Hot scuffing . 45 7.7.4 Cold scuffing 47 8 Materials and heat treatment . 48 8.1 Materials 48 8.1.1 Material requirements for steels recommended in ANSI/AGMA 2003-C10 48 8.1

17、.2 Material form . 49 8.2 Carburizing steels for aerospace bevel gears . 52 8.2.1 Heat treatment of carburizing steels . 52 AMERICAN GEAR MANUFACTURERS ASSOCIATION AGMA 937-A12 AGMA 2012 All rights reserved v 8.3 Induction case hardening of steels for aerospace bevel gears . 53 8.4 Nitrided gears 53

18、 8.5 Through hardened steels 53 9 Manufacturing 53 9.1 Raw material . 53 9.1.1 Forging versus bar stock for aerospace bevel gears 53 9.1.2 Documentation and traceability . 54 9.2 Blank forming 55 9.3 Welding . 55 9.3.1 Joint design . 55 9.3.2 Welding sequence . 55 9.3.3 Weld selection . 56 9.3.4 Ine

19、rtia welding . 57 9.3.5 Electron beam (EB) welding 57 9.3.6 Laser welding 58 9.3.7 Weld defects 58 9.3.8 Weld inspection . 58 9.4 Masking (before or after tooth cutting) 59 9.4.1 Preoxidation treatments 59 9.4.2 Copper plating . 59 9.4.3 Extra material 60 9.4.4 Paint on masking materials . 60 9.4.5

20、Different types of platings 60 9.5 Tooth cutting 60 9.5.1 Face milling . 61 9.5.2 Face hobbing . 62 9.6 Heat treatment . 62 9.6.1 Multiple hardening depths . 62 9.7 Tensile strength coupons 62 9.8 Gear tooth grinding . 63 9.9 Shot peening . 63 9.10 Surface treatment 63 9.10.1 Additive surface treatm

21、ents . 64 9.10.2 Subtractive surface treatments . 64 9.11 Identification and serialization . 64 9.11.1 Marking (see ANSI/AGMA 2005-D03) 66 9.11.2 Quality documentation 66 9.12 Handling/storage/protection 67 10 Bevel gear tooth pattern development . 67 10.1 Bevel gear design requirements . 68 10.2 Pa

22、ttern development . 68 10.2.1 Dimension sheet 68 10.2.2 Tooth contact analysis (TCA) 68 10.2.3 Loaded tooth contact analysis (LTCA) 69 10.2.4 Tooth stress analysis 69 10.2.5 Experimental verification of loaded contact pattern 69 10.2.6 Experimental verification static strain survey . 69 10.2.7 Exper

23、imental verification dynamic strain survey 70 10.2.8 Experimental verification contact stresses . 70 AMERICAN GEAR MANUFACTURERS ASSOCIATION AGMA 937-A12 AGMA 2012 All rights reserved vi 10.3 Developed contact patterns 71 11 Quality control 71 11.1 Inspections 71 11.1.1 Blank . 71 11.1.2 Gear tooth

24、quality 71 11.1.3 Contact pattern 71 11.1.4 Surface roughness quality control . 76 11.2 Nondestructive evaluation . 76 11.2.1 Magnetic particle inspection 76 11.2.2 Surface temper inspection 78 11.2.3 Ultrasonic testing inspection (UT) . 79 11.2.4 Penetrant inspection . 79 11.2.5 Hardness testing .

25、80 11.2.6 Barkhausen noise inspection 80 11.2.7 Destructive evaluation . 80 11.3 Record keeping . 80 12 Drawing definition 80 13 Lubrication . 81 13.1 Function of lubricating oil 81 13.2 Oil delivery . 81 13.3 Composition of oils 83 13.4 Viscosity 84 13.5 Oxidation . 84 13.6 Oil development 84 13.7

26、Lubricants for space environment . 84 13.7.1 Grease lubricants 84 13.7.2 Dry lubricants 84 14 Housing design 85 15 Assembly . 86 16 Bevel gear application testing 86 16.1 Deflection testing and tooth contact checking . 86 16.1.1 Purpose . 86 16.1.2 Method 86 16.1.3 Loading sequence . 87 16.1.4 Extre

27、me temperature testing . 87 16.1.5 Tooth contact check 87 16.1.6 Deflection testing . 87 16.2 Verification testing . 88 16.2.1 Gear stress/strain measurement . 88 16.2.2 Life test 88 16.2.3 Component modal testing . 89 16.3 Special tests 89 16.3.1 Green runs 89 16.3.2 Production acceptance test . 89

28、 16.3.3 Environmental testing 89 16.3.4 Loss of lubricant testing 90 16.4 Test stand design 90 16.4.1 Simple in-line . 90 16.4.2 Four square . 90 AMERICAN GEAR MANUFACTURERS ASSOCIATION AGMA 937-A12 AGMA 2012 All rights reserved vii Annexes Annex A (informative) Isotropic superfinishing process 91 A

29、nnex B (informative) Example of load distribution factor analysis Method B . 97 Annex C (informative) Quality control and measurement of surface roughness 108 Annex D Bibliography 129 Tables Table 1 - Symbols and definitions . 2 Table 2 - Selection of bevel gear types . 9 Table 3 - Material factors

30、12 Table 4 - Minimum number of pinion teeth to prevent undercut . 13 Table 5 - Suggested depth factor, k1. 18 Table 6 - Mean addendum factor, c1. 19 Table 7 - Sum of dedendum angles, 19 Table 8 - Dedendum angles, Pand G. 19 Table 9 - Minimum normal backlash allowance (measured at the outer cone) 21

31、Table 10 - Straight, zerol and spiral bevel formulas . 21 Table 11 - Final processes 27 Table 12 - Typical bearing support arrangements for aerospace spiral bevel gears 32 Table 13 - Typical minimum bending stress limit load margin of safety, MS, values by application . 43 Table 14 - Typical bevel g

32、ear allowable contact temperature number limits1)46 Table 15 - Typical aerospace bevel gear materials 49 Table 16 - Typical aerospace bearing materials . 50 Table 17 - Major metallurgical features affecting aerospace gears 50 Table 18 - Typical aerospace carburizing steels. 52 Table 19 - Relative fo

33、rgeability . 54 Table 20 - Recommended preheat and post-heat temperatures for common gear alloys . 56 Table 21 - Example of CE values for aerospace materials . 56 Table 22 - Additive surface treatments . 65 Table 23 - Magnetic particle inspection acceptance criteria . 77 Table 24 - Temper etch accep

34、tance criteria for aerospace gearing . 78 Table 25 - Drawing format basic outline for bevel gears 82 Figures Figure 1 - Bevel gear cross sectional view . 6 Figure 2 - Straight bevel gear 7 Figure 3 - Spiral bevel gear set . 7 Figure 4 - Zerol bevel gear set 7 Figure 5 - Pinion pitch diameter versus

35、pinion torque pitting resistance . 11 Figure 6 - Pinion pitch diameter versus pinion torque bending strength . 11 Figure 7 - Suggested numbers of teeth in pinion spiral bevel 12 Figure 8 - Suggested numbers of teeth in pinion straight bevel and zerol bevel gears . 13 Figure 9 - Face width of spiral

36、bevel gears operating at 90 degree shaft angle . 14 Figure 10 - Face contact ratio for spiral bevel gears 15 Figure 11 - Bevel gear tooth tapers 16 Figure 12 - Root line tilt . 17 Figure 13 - Bevel gear depth-wise tapers . 17 Figure 14 - Circular thickness factor, k320 Figure 15 - Locating faces and

37、 pilot diameters . 23 Figure 16 - Tooth backing . 24 Figure 17 - Gear web 24 Figure 18 - Cutter clearance . 25 Figure 19 - Light load pattern on silver plated gear 26 Figure 20 - Example of differing surface roughness with similar Ravalue, but with greatly differing performance 28 Figure 21 - Symmet

38、ric rotor with inboard correction planes, (LI-II 1/3 LBearing) 30 Figure 22 - Narrow and overhung rotors (LI-II75 (15,000) Speed ratio (gear/pinion) 1:1 to 10:1 Efficiency Good Better Best Noise Good Better BestPower capacity Lowest Low-medium Highest Production cost Lowest Highest Required mounting

39、 accuracy Lowest Highest AMERICAN GEAR MANUFACTURERS ASSOCIATION AGMA 937-A12 AGMA 2012 All rights reserved 10 6.1.2 Special operating considerations Consideration should be given to any special or adverse operating conditions such as one or more of the following: - high or excessively low ambient t

40、emperature; - presence of corrosive elements; - extreme repetitive shock or reversing loads. The above list is not intended to be all inclusive. 6.1.3 Estimated pinion size The following sections discuss a process for determining the initial approximate size of a bevel pinion for an aerospace applic

41、ation using standards set forth based on commercial quality gearing. This sizing method is conservative and should be further refined by the gear designer based on actual gear tooth loading analysis, the material properties of the steel and other sizing considerations. The sizing method requires sel

42、ecting a design torque and then using Figure 5 and Figure 6 which relate design torque to pinion size to determine an initial pinion size for gear set. The design torque used for sizing should consider the factors described in 6.1.2. If the duty cycle for the gears has one predominant operating torq

43、ue, this may be a good value for initial sizing. If there is a peak torque in the duty cycle much higher than the normal operating torque, this high torque may need to be used for initial sizing. If the duty cycle is defined by power conditions, equation 1 can be used to convert power to torque need

44、ed to use Figure 5 and Figure 6. 9550PPPTn (1M) 63,025PPPTn(1) where TPis pinion torque, Nm (in-lb); P is power, kW (HP); nPis pinion speed, rpm. NOTE: Once the preliminary gear size is determined as explained above, the tooth proportions of the gears should be established and the resulting design s

45、hould be checked for bending strength and pitting resistance. Consideration should be given to the primary mode of failure based upon the application. In applications where failure onset detection is important (main power and accessory drives) it may be desirable that the primary mode should be surf

46、ace durability. This would enable failure detection systems such as chip detectors or vibration monitoring to identify pending failure before loss of power transmission. In applications such as actuators, the ultimate load can determine the sizing of the gear teeth. The bending strength at this ulti

47、mate load can become the critical design load. 6.1.3.1 Spiral bevels Figure 5 and Figure 6 relate the size of commercial quality, case hardened spiral bevel pinions to pinion torque. The charts are for 90 degree shaft angle design. For aerospace bevel gear applications with case hardened steel, or b

48、evel gear applications with other than 90 degree shaft angle designs, the preliminary gear size estimate is less accurate and will require additional adjustments based on the rating calculations. 6.1.3.2 Straight and zerol bevels Straight bevel and zerol bevel gears will always be slightly larger th

49、an spiral bevels. The values of pinion pitch diameter obtained from Figure 5 and Figure 6 are to be multiplied by 1.3 for zerol bevel gears and 1.2 for straight bevel gears. The larger diameter for the zerol bevel gears is due to a face width limitation. AMERICAN GEAR MANUFACTURERS ASSOCIATION AGMA 937-A12 AGMA 2012 All rights reserved 11 Figure 5 - Pinion pitch diameter versus pinion torque pitting resistance Figure 6 - Pinion pitch diameter versus pinion torque bending strength 6.1.3.3 Ground surface roughness gears Gear