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 entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising theref
2、rom, 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. Copyright 2011 SAE International All rights reserved. No part of this publication ma
3、y be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-4970 (outside US
4、A) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AIR6082AEROSPACEINFORMATIONREPORTAIR6082 Issued 2011-05 Calculations to Determine Dimensions fo
5、r Backup Rings to AS5781, AS5782, AS5860, AS5861 RATIONALEPrevious parts standards that were originally developed for backup rings used dimensions that were based only on the fit to hardware and O-ring dimensions at ambient. However, backup rings to AS5781, AS5782, AS5860, AS5861 were designed to su
6、it practical operating conditions and machining capabilities of the material. Thus, there is a requirement for a document that provides the means to determine the dimensions for these backup rings. This document has been compiled to meet this need. FOREWORDScarf cut backup rings to AS5781 and AS5860
7、 are dimensioned to accommodate cylinder breathing and thermal shrink at low temperature while maintaining a 50% minimum lap at the scarf cut. They are also designed, where possible, to ensure an axial clearance between the O-Ring, backup ring(s) and groove at high temperature with an overlap condit
8、ion at the scarf cut. These calculations under thermal conditions do not account for thermal changes to any of the hardware. Solid uncut backup rings to AS5782 and AS5861 are dimensioned in line with practical tolerances on diameters. TABLE OF CONTENTS 1. SCOPE . 32. REFERENCES. 32.1 Applicable Docu
9、ments . 32.1.1 SAE Publications 32.1.2 U.S. Government Publications . 42.2 DEFINITIONS 42.3 Abbreviations . 52.3.1 General 52.3.2 Abbreviations used in Equations 53. DESIGN CALCULATIONS FOR BACKUP RINGS 73.1 Backup Ring Thickness “T” (Axial Dimension) 73.1.1 Axial Clearance Calculations . 83.2 Radia
10、l Wall Dimension of Backup Rings “W” dimension . 113.2.1 Piston Backup Rings 113.2.2 Rod Backup Rings . 123.3 Backup Ring Diameters . 133.3.1 Solid (uncut) Backup Rings 133.3.2 Diameter of Scarf-cut Backup Rings 143.4 Axial Clearance Calculations . 213.4.1 Axial Clearance Scarf-cut Piston Backup Rin
11、gs . 213.4.2 Axial Clearance Scarf-cut Rod Backup Rings 243.4.3 Axial Clearance Solid Backup Rings 25Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR6082 Page 2 of 383.5 Cross Section Area Occ
12、upancy Calculations 263.5.1 Cross Section Area Occupancy Check on Scarf-cut Backup Rings atMaximum Overlap Position 263.5.2 Cross Section Area Occupancy Check on Solid (Uncut) Backup Rings . 293.6 Volume Occupancy Calculations . 303.6.1 Volume Occupancy Check - Scarf-cut Piston Backup Rings 303.6.2
13、Volume Occupancy Check Scarf-cut Rod Backup Rings . 323.6.3 Volume Occupancy Check Solid (Uncut) Backup Rings 344. GLAND AND BACKUP RING DESIGN PRACTICES 345. SPREADSHEETS FOR AS5781, AS5782, AS5960, AS5861 . 346. NOTES . 346.1 Change Status . 34FIGURE 1 GLAND DESIGN AS4716, AS5857 . 4FIGURE 2 SCARF
14、-CUT BACKUP RING CONTROLLED FEATURES AS5781, AS5860 . 4FIGURE 3 SOLID BACKUP RING CONTROLLED . 5FIGURE 4 COMPRESSED O-RING WITH SINGLE BACKUP IN PISTON SEAL GLAND 8FIGURE 5 COMPRESSED O-RING WITH TWO BACKUPS IN PISTON SEAL GLAND 8FIGURE 6 O-RING IN FREE CONDITION 9FIGURE 7 COMPRESSED O-RING IN ZERO
15、BACKUP WIDTH PISTON SEAL GLAND . 9FIGURE 8 AXIAL CLEARANCE “Z” WITH O-RING Packing, Hydraulic, General Requirements For (Inactive for New Design) FED-STD-595 Colors Used in Government Procurement 2.2 DEFINITIONS GLAND DESIGN DIMENSIONS: The key hardware dimensions for glands, as defined in AS4716 an
16、d AS5857, are as shown in Figure 1. FIGURE 1 KEY DIMENSIONS FOR GLAND DESIGN - AS4716, AS5857 BACKUP RING DIMENSIONS: The key hardware dimensions for backup rings, as defined in AS5781, AS5782, AS5860 and AS5861, are as shown in Figures 2 and 3. FIGURE 2 - KEY DIMENSIONS FOR SCARF-CUT BACKUP RING -
17、AS5781, AS5860 Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR6082 Page 5 of 38FIGURE 3 - KEY DIMENSIONS FOR SOLID BACKUP RING - AS5782, AS5861 BACKUP VOLUME: This is the volume of the backup
18、 ring and is calculated at ambient temperature and at the maximum operating temperature of 275 F (135 C) for gland occupancy purposes.RACETRACK SHAPE: This is the shape of a squeezed O-ring cross section as shown in Figures 4, 5, and 7 (Refer to 3.1.1).2.3 Abbreviations 2.3.1 General B/U Backup Ring
19、 C/X Cross Section I.D. Inside Diameter Nom Nominal dimension O.D. Outside Diameter PTFE Polytetrafluoroethylene t Temperature Tol Tolerance dimension Typ Typical 2.3.2 Abbreviations used in Equations 2.3.2.1 General Abbreviations BVCYHBackup Volume O-ring I.D. O ring radius to mean of cross-section
20、 O-ring cross section radius G Maximum gap at scarf-cut when held against gauge G1Groove width, one backup Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR6082 Page 6 of 38G2Groove width, two
21、backup GAR1 Groove cross-section area perpendicular sidewalls, including corner radii, 1 backup groove widthGAR2 Groove cross-section area perpendicular sidewalls, including corner radii, 2 backup groove width GV1 Groove volume perpendicular sidewalls, excluding corner radii, 1 backup groove width G
22、V2 Groove volume perpendicular sidewalls, excluding corner radii, 2 backup groove width GVR1 Groove volume perpendicular sidewalls, including corner radii, 1 backup groove width GVR2 Groove volume perpendicular sidewalls, including corner radii, 2 backup groove width H O-ring radius to center of C/X
23、 l Length of flat on racetrack shape of squeezed O-ring cross section L Overall axial length of O-ring when installed in compressed condition LeOverall axial length of O-ring when installed in compressed condition and at temperature due to thermal expansionP O-ring I.D. (maximum) PS Radial groove de
24、pth q Cross section of O-ring when in compressed installed condition Q O-ring cross section diameter in the free condition R Groove corner radius RA2 Area of two (2) groove corner radii RV2 Volume of two (2) groove corner radii T Backup thickness (axial length) TExpBackup thickness (max) at overlapp
25、ed scarf cut when expanded at 275 F (135 C) V O-ring Volume (maximum tolerances) VEO-ring Volume, maximum, at elevated temperature due to thermal expansion W Backup ring radial width X Backup ring shrink due to thermal contraction Y O-ring section radius Z1Axial clearance in groove with O-ring and 1
26、 backup installed Z2Axial clearance in groove with O-ring and 2 backups installed 2.3.2.2 Abbreviations Specific to Piston Type Applications A Scarf-cut angle measured from face of backup ring A Cylinder bore diameter d Backup inside diameter, solid backups/scarf cut backups D Backup outside diamete
27、r, solid backups / scarf cut backups DIncIncrease in Backup O.D. to maintain 50% lap requirement F Groove diameter L1Scarf-cut circumferential length, measured at part O.D. L2Scarf-cut circumferential length, measured at part I.D. N Cylinder increased diameter due to breathing Copyright SAE Internat
28、ional Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR6082 Page 7 of 382.3.2.3 Abbreviations Specific to Rod Type Applications A Scarf-cut angle in relation to face of backup ring B Rod diameter d Backup inside diameter,
29、 solid backups / scarf cut backups D Backup outside diameter, solid backups / scarf cut backups E Rod gland groove diameter L2Scarf-cut circumferential length, measured at part I.D. 3. DESIGN CALCULATIONS FOR BACKUP RINGS NOTE: Some equations are repeated in this section 3.1 Backup Ring Thickness “T
30、” (Axial Dimension) When being created, the committee charter for thickness (axial length) for all backup rings to AS5781, AS5782, AS5860 and AS5861 was to at least match some popular manufacturer standards. This was followed as closely as possible while maintaining a volume fill below 100% at maxim
31、um operating temperature and using PTFE and elastomer materials with the highest linear coefficient of thermal expansion for worst case conditions. TNom= Nominal thickness of the backup ring Tolerance on thickness for all Dash Sizes = 0.002 in ( 0.051 mm) Table 1 provides the nominal thicknesses of
32、the SAE standard backup rings. TABLE 1 - T DIMENSIONS FOR BACKUP RINGS BY SPECIFICATION AND BY DASH SIZE SERIES BACKUP RING SPECIFICATIONDASH SIZE SERIESTNom(inches) TNom(mm) AS5781, AS5782 000 0.050 1.27 100 0.058 1.47 200 0.062 1.57 300 0.088 2.24 400 0.129 3.28 AS5860, AS5861 000 0.054 1.37 100 0
33、.058 1.47 200 0.062 1.57 300 0.088 2.24 400 0.128 3.25 It should be noted that the TNomdimension is different for AS5781, AS5782 in some cases compared to AS5860, AS5861. The reason for this is that AS5857 uses a higher squeeze than AS4716, which produces a longer axial length in the O-ring when ins
34、talled (squeezed). While in most cases AS5857 uses the same groove widths as AS4716, some groove widths in AS5857 are increased in order to prevent overoccupancy (more than 100%) at maximum operating temperature. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo repr
35、oduction or networking permitted without license from IHS-,-,-SAE AIR6082 Page 8 of 383.1.1 Axial Clearance Calculations Calculate the axial clearance for solid backups and scarf cut backups at positions other than at scarf-cut lap. Refer to Figures 4 and 5 FIGURE 4 - COMPRESSED O-RING WITH SINGLE B
36、ACKUP IN PISTON SEAL GLAND FIGURE 5 - COMPRESSED O-RING WITH TWO BACKUPS IN PISTON SEAL GLAND For One Backup Width: Clearance = Groove Width (Axial Length of O-ring + Axial Length of One Backup) Clearance Z1= G1min (Lmax+ Tmax) (Eq. 1) For Two Backups Width: Clearance = Groove Width (Axial Length of
37、 O-ring + Axial Length of Two Backups) Clearance Z2= G2min (Lmax+ 2Tmax) (Eq. 2) 3.1.1.1 Calculate the Overall Length of the Squeezed O-Ring Refer to Figures 6 and 7 Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without licens
38、e from IHS-,-,-SAE AIR6082 Page 9 of 38FIGURE 6 - O-RING IN FREE CONDITION FIGURE 7 - COMPRESSED O-RING IN ZERO BACKUP WIDTH PISTON SEAL GLAND Area of O-ring cross section = 4Q2S(Eq. 3) Assume that when squeezed, the O-ring maintains the same total cross sectional area as in the free condition, then
39、 q4q4Q22S Sl (Eq. 4) andL = q + l (Eq. 5) From the above, it can be deduced that the O-ring Overall Length (L) when squeezed is: L = qqqQ42MaxS(Eq. 6) NOTE: Use maximum O-ring QMaxcross section tolerance diameter dimension for worst case condition Copyright SAE International Provided by IHS under li
40、cense with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR6082 Page 10 of 383.1.1.2 Established Groove Widths As a result of calculations for the AS5860 Volumetric Gland Occupancy, the groove widths for AS5857 are larger from those of AS4716 in order to
41、accomodate the more highly squeezed O-ring while maintaining backups of sufficient thickness (axial length) to maintain integrity of design. Tables 2A, 2B, 2C, and 2D below list the groove widths for comparison purposes. TABLE 2A AS 4716 STANDARD GROOVE WIDTH FOR ZERO, ONE, AND TWO BACKUP IN INCHES
42、GLAND AND AS568DASH NO O-RINGCROSSSECTIONWMINO-RINGCROSSSECTIONWMAXGROOVEWIDTH G0NOBACKUPRING MINGROOVEWIDTH G0NOBACKUPRINGMAXGROOVEWIDTH G1ONEBACKUPRING MINGROOVEWIDTH G1ONEBACKUPRINGMAXGROOVEWIDTH G2TWOBACKUPRINGSMINGROOVEWIDTH G2TWOBACKUPRINGSMAX001 0.037 0.043 0.070 0.075 - - - - 002 0.047 0.053
43、 0.077 0.082 - - - - 003 0.057 0.063 0.088 0.093 - - - - 004 to 007 0.067 0.073 0.098 0.103 0.154 0.164 0.210 0.220 008 to 028 0.067 0.073 0.094 0.099 0.150 0.160 0.207 0.217 104 to 149 0.100 0.106 0.141 0.151 0.183 0.193 0.245 0.255 210 to 247 0.135 0.143 0.188 0.198 0.235 0.245 0.304 0.314 325 to
44、349 0.205 0.215 0.281 0.291 0.334 0.344 0.424 0.434 424 to 460 0.269 0.281 0.375 0.385 0.475 0.485 0.579 0.589 TABLE 2B AS 4716 STANDARD GLAND WIDTH FOR ZERO, ONE, AND TWO BACKUP IN MILLIMETERS GLAND AND AS568DASH NO O-RINGCROSSSECTIONWMINO-RINGCROSSSECTIONWMAXGROOVEWIDTH G0NOBACKUPRING MINGROOVEWID
45、TH G0NOBACKUPRINGMAXGROOVEWIDTH G1ONEBACKUPRING MINGROOVEWIDTH G1ONEBACKUPRINGMAXGROOVEWIDTH G2TWOBACKUPRINGSMINGROOVEWIDTH G2TWOBACKUPRINGSMAX0010.94 1.09 1.78 1.91 - - - - 0021.19 1.35 1.96 2.08 - - - - 0031.45 1.60 2.24 2.36 - - - - 004 to 007 1.70 1.85 2.49 2.62 3.91 4.17 5.33 5.59 008 to 028 1.
46、70 1.85 2.39 2.51 3.81 4.06 5.26 5.51 104 to 149 2.54 2.69 3.58 3.84 4.65 4.90 6.22 6.48 210 to 247 3.43 3.63 4.78 5.03 5.97 6.22 7.72 7.98 325 to 349 5.21 5.46 7.14 7.39 8.48 8.74 10.77 11.02 424 to 460 6.83 7.14 9.53 9.78 12.07 12.32 14.71 14.96 Copyright SAE International Provided by IHS under li
47、cense with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR6082 Page 11 of 38TABLE 2C AS5857 STANDARD GROOVE WIDTH FOR ZERO, ONE, AND TWO BACKUP IN INCHES GLAND AND AS568DASH NO O-RINGCROSSSECTIONWMINO-RINGCROSSSECTIONWMAXGROOVEWIDTH G0NOBACKUPRING MINGRO
48、OVEWIDTH G0NOBACKUPRINGMAXGROOVEWIDTH G1ONEBACKUPRING MINGROOVEWIDTH G1ONEBACKUPRINGMAXGROOVEWIDTH G2TWOBACKUPRINGSMINGROOVEWIDTH G2TWOBACKUPRINGSMAX001 0.037 0.043 0.090 0.095 - - - - 002 0.047 0.053 0.095 0.100 - - - - 003 0.057 0.063 0.105 0.110 - - - - 004 to 007 0.067 0.073 0.115 0.120 0.174 0.184 0.230 0.240 008 to 028 0.067 0.073 0.105 0.110 0.164 0.174 0.220 0.230 104 to 109 0.100 0.10
