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.Copyright 2006 SAE InternationalAll rights reserved. No part of this publication may be
3、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: 724-776-4970 (outside USA)Fax: 724-
4、776-0790Email: CustomerServicesae.orgSAE WEB ADDRESS: http:/www.sae.orgSURFACEVEHICLERECOMMENDEDPRACTICEJ1121REV.SEP2006Issued 1975-11Revised 2006-09Superseding J1121 JUL1988Helical Compression and Extension Spring Terminology1. ScopeThe following recommended practice has been developed to assist en
5、gineers and designers in thepreparation of specifications for the major types of helical compression and extension springs. It is restrictedto a concise presentation of items which will promote an adequate understanding between springmanufacturer and spring user of the major practical requirements i
6、n the finished spring. Closer tolerances areobtainable where greater accuracy is required and the increased cost is justified.For the basic concepts underlying the spring design and for many of the details, see the SAE InformationReport MANUAL ON DESIGN AND APPLICATION OF HELICAL AND SPIRAL SPRINGS,
7、 SAE HS 795,which is available from SAE Headquarters in Warrendale, PA 15096. A uniform method for specifying designinformation is shown in the TYPICAL DESIGN CHECK LISTS FOR HELICAL SPRINGS, SAE J1122.Two types of helical springs are considered:a. Hot coiled compression springs for general automoti
8、ve use as well as for motor vehicle suspensions.b. Cold wound compression and extension springs for general automotive use.This recommended practice uses SI (metric) units in accordance with the provisions of SAE TSB 003.1.1 RationaleJ1121 has been reviewed and updated to reflect the current industr
9、y Standards.2. References2.1 Applicable PublicationsThe following publications form a part of the specification to the extent specifiedherein. Unless otherwise indicated the latest revision of SAE publications shall apply.2.1.1 SAE PUBLICATIONSAvailable from SAE, 400 Commonwealth Drive, Warrendale,
10、PA 15096-0001, Tel:877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org.SAE HS 84Manual on Shot PeeningSAE J217Stainless Steel 17-7 PH Spring Wire and SpringsSAE J230Stainless Steel, SAE 30302, Spring Wire and SpringsSAE J461Wrought and Cast Copper AlloysSAE HS J795SAE Man
11、ual on Design and Application of Helical and Spiral SpringsSAE J1122Helical Springs: Specification Check ListsSAE TSB 003Rules for SAE Use of SAE (Metric) UnitsCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from
12、 IHS-,-,-SAE J1121 Revised SEP2006-2-2.1.2 ASTM PUBLICATIONSAvailable from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959,Tel: 610-832-9585, www.astm.org.ASTM A232/A232M-99Standard Specification for Chromium-Vanadium Alloy Steel Valve Spring QualityWireASTM A227/A227M-99Standard Speci
13、fication for Steel Wire, Cold-Drawn for Mechanical SpringsASTM A228/A228M-02Standard Specification for Steel Wire, Music Spring QualityASTM A229/A229M-99Standard Specification for Steel Wire, Oil-Tempered for Mechanical SpringsASTM A230/A230M-99Standard Specification for Steel Wire, Oil-Tempered Car
14、bon Valve Spring QualityASTM A401/A401M-03Standard Specification for Steel Wire, Chromium-Silicon AlloyASTM A679/A679M-00Standard Specification for Steel Wire, High Tensile Strength, Cold Drawn3. Hot Coiled Springs3.1 Materials and Heat TreatmentRound spring steel bars are available in carbon and al
15、loy analyses. The barsare generally used in the “as rolled” condition (either commercial hot rolled or precision hot rolled), but theymay be centerless ground before coiling.The heat treatment necessary to develop the required physical properties of the material may be accomplishedby direct quench i
16、mmediately after coiling, or by allowing the coiled spring to cool to a temperature below thecritical, then reheating to the required temperature and quenching; the quench is followed by tempering toproduce the specified hardness.Table 1 lists available materials. Their hardenability limitations dic
17、tate maximum bar size. For tensile andtorsional properties, see MANUAL, SAE HS 795, Chapter 2, Table 2.21.3.2 Shot PeeningShot peening is used to increase the fatigue life of springs. It consists of subjecting the springto a stream of shot moving at high velocity. The peening action of the shot redu
18、ces the effect of surface defectsand sets up beneficial stresses in a thin surface layer. It also results in cold working this layer. To be effective,the peening must reach the area of highest stress which for helical compression springs is the inside diameterof the coil.TABLE 1MATERIALS FOR HOT COI
19、LED COMPRESSION SPRINGSMaterials SpecificationMax. Bar(1)Dia., mm1. Based on a through hardened bar of 444 HB typical hardness ranges are 444 - 495 HB and 461 - 514 HB.Carbon Steels SAE 1085 10SAE 1095 10Carbon Boron Steel SAE 15B62H 25Alloy Steels SAE 5150 H 10SAE 5160 H 20SAE 9260 H 10SAE 51B60H 3
20、0SAE 4161 H 60SAE 6150 H 10Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1121 Revised SEP2006-3-The fatigue life of hot coiled springs is greatly impaired when the bar surface is afflicted by
21、such flaws asimpurities, cracks, seams, or decarburization, but it can be increased by the peening operation in the order of 4to 1. Even the much better fatigue life attainable in hot-coiled springs with nearly perfect bar surface will beimproved by peening in the order of more than 2 to 1. For furt
22、her details see MANUAL, SAE HS J795,Chapters 1 and 4, also SHOT PEENING MANUAL, SAE HS 84 J808.3.3 PresettingPresetting (also called scragging, cold setting, or bulldozing) is an operation during themanufacturing process in which the spring is compressed beyond the yield point of the heat treated ma
23、terial.In preparation for this, the spring is coiled to a free length in excess of the designated free length. The yieldingin the surface layers of the bar which occurs during presetting produces beneficial residual stresses, thusincreasing the elastic limit and thereby reducing the chances of settl
24、ing in subsequent service. The yieldingcauses the spring to take a permanent set, thus bringing it down to the designated free length. See alsoPreset Length, 3.6.3.3.3.1 WARM SETTINGIn order to reduce the “sag” of “settling” of helical suspension springs which occurs whenthey are subjected to vehicl
25、e loading over time, it has become common practice to warm set the spring at anelevated temperature (usually about 200 C depending on the particular spring design). One theory holdsthat the major benefit of this operation results from an increase in the amount of strain hardening that occurswhen the
26、 spring is stressed past the proportional limit (point “A” in Figure 1). Increasing the temperaturelowers the proportional limit to some stress lower than point “A”, and therefore if the spring is still stressed topoint “B”, the amount of strain hardening that occurs is greater. This increase in str
27、ain hardening will reducethe dynamic or static settling (load loss) that occurs over the useful life of the spring.FIGURE 1TYPICAL LOAD-DEFLECTION DIAGRAM OF HELICAL SPRING DURING PRESETTINGA second theory is that a more effective beneficial residual stress pattern is set up over the bar cross secti
28、on,when a spring is warm set at elevated temperature.It should be noted that a final (cold) presetting operation is still necessary.In general, warm setting will decrease the load loss by more than 50%, depending on the working stresslevel.3.4 Bar Diameter and LengthRound bars are hot rolled to any
29、desired diameter between 9 and 100 mm. Table2 shows the cross section tolerances for commercial hot rolled bars. Bars may be precision hot rolled with 50%of the tolerances in Table 2, or they may be centerless ground with 25% of the tolerances in Table 2.Bars are commonly purchased in the exact leng
30、th required to produce one spring. Tolerances for bar lengthsare shown in Table 3.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1121 Revised SEP2006-4-3.5 Coil DiameterThe coil diameter can be
31、 expressed in terms of the mean coil diameter (D) which is used inthe rate and stress formulae. However, coil diameter tolerances should be specified on either the insidediameter (ID) or the outside diameter (OD) of the coils, depending upon the importance of the respectivedimensions to the user. To
32、lerances are shown in Table 4, based on coil diameter and spring length.For motor vehicle suspension springs, it is customary to specify the ID in order to facilitate the coiling of afamily of springs on a single arbor.3.6 Spring LengthsSpring lengths are to be measured after preloading (see Preload
33、 Length, 3.6.4), as thedistance parallel to the spring axis between the end surfaces, or else between two reference points specifiedon the spring drawing.TABLE 2CROSS SECTION TOLERANCES FOR HOT ROLLED CARBONAND ALLOY STEEL ROUND BARSSpecifiedDiameter, mmOverSpecifiedDiameter, mmThruTolerance,Plus an
34、d Minus,mmOut ofRound,mm 10 0.15 0.2210 15 0.18 0.2715 20 0.20 0.3020 25 0.23 0.3425 30 0.25 0.3830 35 0.30 0.4535 40 0.35 0.5240 60 0.40 0.6060 80 0.60 0.9080 100 0.80 1.20TABLE 3LENGTH TOLERANCES FOR HOT ROLLED CARBONAND ALLOY ROUND STEEL BARSSpecifiedDiameter, mmOverSpecifiedDiameter, mmThruLengt
35、h Tolerance,Plus Only, mmFor Lengths, mmOverThruLength Tolerance,Plus Only, mmFor Lengths, mm15003000Length Tolerance,Plus Only, mmFor Lengths, mm300025 12 2025 50 16 2550 100 25 40TABLE 4COIL DIAMETER TOLERANCESFor Specified orComputedOutsideDiameter, mmInside or OutsideDiameterTolerance,Plus and M
36、inus, mmFor Free SpringLength, mmUp to250Inside or OutsideDiameterTolerance,Plus and Minus, mmFor Free SpringLength, mmOver250 thru450Inside or OutsideDiameterTolerance,Plus and Minus, mmFor Free SpringLength, mmOver450 thru650Inside or OutsideDiameterTolerance,Plus and Minus, mmFor Free SpringLengt
37、h, mmOver650 thru850Inside or OutsideDiameterTolerance,Plus and Minus, mmFor Free SpringLength, mmOver850 thru105075.0 thru 110.0 0.8 1.3 2.5 3.6 4.6Over 110.0 thru 150.0 1.3 2.5 3.6 4.6 5.6Over 150.0 thru 200.0 2.5 3.6 4.6 5.6 6.6Over 200.0 thru 300.0 3.6 4.6 5.6 6.6 6.6Copyright SAE International
38、Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1121 Revised SEP2006-5-3.6.1 FREE LENGTHFree length is the length when no external load is applied. When load is specified, freelength is used as a reference dimension only.
39、When load is not specified, free length tolerance equals(1.5 mm + 4% of free-to-solid deflection).3.6.2 SOLID LENGTH (SEE ALSO NUMBER OF COILS, 3.7)Solid length is the length when the spring is compressedwith an applied load sufficient to bring all coils in contact; for practical purposes, this appl
40、ied load is taken toequal approximately 150% of the load beyond which no appreciable deflection takes place.3.6.3 PRESET LENGTHIn the presetting operation (see Presetting, 3.3), the spring is usually compressed solid.However, if the stress at solid length is so high that the spring would be excessiv
41、ely distorted, the presettingoperation may only be carried to a specified preset length. If more than one preset compression is desired,this must be specified on the drawing. See Also MANUAL, SAE HS 795, Chapters 1 and 4.3.6.4 PRELOAD LENGTHPreloading is the operation of deflecting the spring to the
42、 preload length in order toremove temporary recovery of free length before the spring is checked for load and rate.If the spring was preset during the manufacturing process to the solid length, the preloading may also becarried to the solid length, but it may be restricted to a preload length slight
43、ly greater than the solid length,provided the maximum deflection during subsequent service will not go below the preload length.If the spring was preset to a specified preset length greater than the solid length, the preloading should berestricted to a preload length greater than the preset length.H
44、owever, the preload length must not exceed the minimum spring length possible in the mechanism forwhich the spring is designed. In suspensions, this is called the “length at metal-to-metal position.” Themetal-to-metal contact will occur in the suspension mechanism when rubber bumpers are disregarded
45、. Thespring deflection from the specified loaded length to the metal-to-metal position is called “clearance.”3.6.5 LOADED LENGTHLoaded length is the length while the load is being measured; it is a fixed dimension, withthe tolerance applied to the load.3.7 Number of CoilsTotal number of coils (Nt) a
46、re counted tip to tip, active number of coils (N) are specified asthe number of working coils at free length. With increasing load, N may progressively decrease due to the“bottoming out” effect. If no appreciable bottoming out occurs, the relationships between N and Ntare asshown in Table 5 which al
47、so gives the formulae for nominal solid length.where:d = bar diametert = tip thickness of taper rolled bar1.01 = factor used to compensate for the cosine effect of the coil helix angleThe bracketed term in the solid length formula for springs with two pigtail ends may vary between (Nt 0.90)and (Nt 1
48、.60), depending on the pigtail details.TABLE 5FORMULAE FOR TOTAL COILS AND FOR NOMINAL SOLID LENGTHEnd ConfigurationTotal Coils (Nt)NominalSolid Length (Ls)Both ends taper rolled N + 2 1.01 d (Nt 1) + 2tBoth ends with tangent tail N + 1.33 1.01 d (Nt+ 1)Both ends with pigtail N + 1.50 1.01 d (Nt 1.2
49、5)Taper rolled plus tangent tail N + 1.67 1.01 d Nt+ 1Taper rolled plus pigtail N + 1.75 1.01 d (Nt 1) + tTangent tail plus pigtail N + 1.42 1.01 d NtCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1121 Revised SEP2006-6-Since nominal solid length may be exceeded somewhat by actual solid length
