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Proceedings of the 7th ICFDM2006International Conference on Frontiers of Design and ManufacturingJune 19-22, 2006, Guangzhou, ChinaTHETHETHETHE SWAGINGSWAGINGSWAGINGSWAGING TECHNOLOGYTECHNOLOGYTECHNOLOGYTECHNOLOGY USEDUSEDUSEDUSED ININININ SHAFTSHAFTSHAFTSHAFT CLINCHINGCLINCHINGCLINCHINGCLINCHINGASSEMBLYASSEMBLYASSEMBLYASSEMBLY FORFORFORFOR AUTOMOTIVEAUTOMOTIVEAUTOMOTIVEAUTOMOTIVE HUBHUBHUBHUB BEARINGBEARINGBEARINGBEARING UNITUNITUNITUNITXiao Yunya 1, 2 , Zhou Zhixiong1and Lv Jianmin31College of Mechanical and Automotive Engineering, Hunan University, China2Department of Electromechanical Engineering, Shaoguan University, China3Shaoguan Southeast Bearing Co., Ltd.,ChinaAbstract:Abstract:Abstract:Abstract: Recently, shaft end clinching is being adopted in the hub bearing unitassembly, which will raise as technological trend and gradually replace clamp nut infuture. In a machine reconstructed from lathe, the sample of shaft end clinched hubunit is successfully manufactured by swaging technology with given parameters.Some tests confirm that the shaft end clinching hub unit has functions greater than thetraditional hub unit with clamp nut. In the end, the future application and the furtherresearch direction of the swaging technology are discussed.KeyKeyKeyKey Words:Words:Words:Words:hub bearing unit, swaging, shaft clinching, assemblyHub unit bearings are widely being adopted for cars as they are lighter andstronger and easily to mounting. In the hub bearing unit assembly, the shaft clinchingtightening replaces clamp nut and becomes technological trend. It is adopted in themostly famous international companies of bearing manufacture. However, thedeformation of the workpiece in clinching process is complex and difficult to becontrolled. It brings phenomenons such as distortion of structure in the connectingarea, shortage of supporting rigidity, inadequacy of strength, disqualification ofrotational accuracy and lack of life. Thus leads the hub unit to invalidation easily. Upto now, the swaging technology used in shaft clinching for hub unit is not wellmastered. With the support from some corporations, the pilot study of the swagingtechnology is completed. The problems from technics and equipment of clinching aresolved, and the sample of swaged edge of hub bearing unit is manufacturedsuccessfully.1. 1. 1. 1. IntroductionIntroductionIntroductionIntroductionHub bearing unit is assembled from several components, which is pre-adjusted andlubricated for life.The unit was originally designed for use in cars and trucks to replace the traditionaltaper roller bearings, which is ready to install and free maintenance. With the hubbearing units not only the number of parts, but also the overall weight of the wheelarrangement is reduced. They also reduce assembly time because they do not requireany special adjustment. Each unit is self-contained andready to be bolted in place. This kind of bearing has come through three generationssince it was designed by SKF in 1938. The 4th generation hub unit is now underdevelopment though it has not yet been mass-produced. Figure 1 illustrates thestructure of hub bearing units 3.The 1st generation hub bearing unit is composed of two single-row bearings withtheir outer rings integrated, where grease is filled with seals. Compared with the 1stgeneration, the 2nd generation hub bearing unit is much more light weight andminiaturization ， which has integrated flange into the outer ring of 1st generationwheel bearing. The 3rd generation hub bearing unit is an advanced type of 2ndgeneration, which the outboard inner ring of the inner-ring rotation type hub unit andhub-shaft are integrated. In this generation hub unit, number of built-inhigh-performance sensor type has increased. 2Figure.1 Hub unit bearingsTo further reduce the weight and size of the hub bearing unit and improve itsreliability, NSK has recently developed a novel shaft end clinching hub unit. In thenew hub design, the clamp nut which fastens the inner and outer rings together isreplaced with a swaged edge. The swaging that used in shaft clinching is a techniquethat deforms the end part of hub shaft by swaging forging in which inboard of innerring and proper shaft force by this deformation. Figure 2 shows examples of 3rdgeneration type clinched shaft hub units for a driven wheel and drive wheelrespectively. In addition, this technique is also applicable to the inner ring rotationtype 2nd generation hub units 2.driven wheeldrive wheelFigure2 Shaft clinching hub unitThere are several advantages of the swaged hub unit in comparison toconventional retaining nut assemblies. The nut is saved in the swaged hub unit. Theswaged hub unitssize is smaller and weight is less than the conventional retainingnut assemblies. The structure of the unit becomes compact. And the vehicle fuelconsumption is reduced 1. The clamping force can be controlled accurately duringthe swaging process. Then the effect of error from parts is avoided. The fluctuation ofpre-adjusted force is reduced greatly. As every hub unit gains the best pre-adjustedforce after assembly, the life of bearing unit can be extended. The clinching tighteningis an un-reversible assembly. The assembly is not failure though the vibration causedfrom running process is been loaded on the hub unit. The shaft clinching process iscapable to perfectly comply with the problem of “loosening of tightening” that wasimpossible to be solved for the nut tightening. Then the shaft clinching improves thereliability and safety of the product greatly. This technology enables resource andenergy of the manufacture of hub bearing unit to be saved. Due to predigest theassembly process, the cost of the whole vehicle is further reduced.2. 2. 2. 2. ProcessProcessProcessProcess andandandand ExperimentExperimentExperimentExperimentThe swaging process is an applied “rocking die forging”. Figure 3 illustrates theprinciple of the rocking die forging 3. On the center point of a workpiece, the axisOY of a conical upper die, which is titled by an angle from the centerline OX ofthe work, is turned about the OX axis. This gives rocking motion to the upper die, andthe workpiece is continuously formed as the upper die continues the rocking rotation.The motions needed by the shaping principle can be achieved from a lathe. AsFigure 4 showing, a rolling head is fixed on the end of the lathe shaft. The head istilted an angle from the centerline of workpiece and self-rotating. The workpiece isfixed on the worktable restructured from the tow- board which is drived by hydraulicpressure. During the rolling process while the tilted rolling head is rotated on thebearing assembly, the shaft end of the flanged inner ring (workpiece) will receive apressure provided from hydraulic-driving worktable and yield plastic deformationuntil it is firmly fixed to the smaller inner ring. Photo 1 shows the reconstructedmachine.Figure3 Principle of the rocking die forgingFigure4 The motions needed by the shaping principleThe rolling head is the key unit device for the swaging experimentation. Figure 5illustrates its structure. It is consisted of a roll-wheel, a bearing, a nut, 3 innerhexangular bolts and a joining- tray. The bearing is a double row angular contact ballbearing, actually a hub bearing unit, which supports both of the double-direction axialforces and the radial force. It ensures the roll-wheel to be self-revolving with theeffect of friction from the contact area between the roll-wheel and the workpieceduring the swaging process. The rolling head is fixed on the lathe shaft with thejoining-tray which can adjust its gradient angle to meet the angle needed between therPhoto 1 The reconstructed machine for swagingIn order to ensure the quality of the clinching assembly, the shape of the rollinghead used in the experimentation should be optimized. It is not enough to only havepurely axial grinding- pressure but also to keep the perfect radial grinding pressures inthe process of the clinching assembly. The key is that the diameter of the ball-head ofthe rolling head should be larger than that of the inner hole of the bearing, and keep anappropriation touching angle. At the same time, the rolling head must be grindingwith no slippage in the process of the swaging so as to avoid the hub unit rotationcaused by the friction when touching each other, thus reducing the quality and theprecision of the clinching assemblyThe swaging process is executed in the reconstructed lathe machine. Althoughthe processing load is small as a result of the rolling head inclination angle , axialand radial loads are applied to the assembly during the swaging process. This canresult in potential adverse effects that influence bearing performance, such asdeformation or stiffness of the rolling elements and raceways. To eliminate or reducethese adverse effects, it thus becomes necessary to confirm the technical parameterthrough the swaging experimentation. After repetitious experiments on swaging, theparameter is confirmed at last. Under the integrated effect of the given parameterswhich includes pressure, loading speed and rotating speed, the sample of swaged endhub unit is successfully manufactured. Photo 2 shows the real product.Figure5 The rolling headPhoto 2 The sample of swaged end hub unit3. 3. 3. 3. ConclusionConclusionConclusionConclusion andandandand DiscussionDiscussionDiscussionDiscussionIn order to examine the static strength of the swaged edge, a static strength testwas carried into execution. A moment load was applied until the bearing failed. At theend, neither the swaged bearing nor the bearing assembled with a clamp nut failed atthe fastening joint. Failure occurred in the flanged inner ring at the corner of themating face with the smaller inner ring. The test determined that the swaged edge wasnot the weak point of the bearing. Photo 3 shows the failure of hub bearing unit. Inaddition, the sample of swaged hub bearing unit also passed the running endurancetest under heavy load. It verified that the swaged edge is sufficient for fatigue strength.It is indicated on the result of the test that swaged hub bearing unit has functionsgreater than the traditional hub bearing unit with clamp nut.Although the feasibility of swaging used in shaft clinching for hub bearing unitassembly is confirmed on the experimentation and the sample of swaged end hub unitis manufactured successfully, but still there are many problems waiting to be solvedbefore mass-produce. In order to master the swaging technology entirely, a generalresearch should be demanded to perform. It includes analyzing the potential failuremode of swaging, simulating the plastic deformation course of the hub unit during theswaging process and optimizing the geometric shape of the shaft edge and roll-wheel.Based on these studies, many base theories of swaging can be constructed and somekey technologies for swaging the hub unit can be mastered. Using these theories andkey technologies, a novel high efficient and precise special swaging machine for shaftclinching hub units will be developed.Photo 3 The failure of hub bearing unitIt is quite important to master the swaging technology for manufacture either the2nd generation and 3rdgeneration hub units or the new generation hub unit. As a hub unit, it shouldincludded bearing assemblies. These new generations of hub bearing unit are notexceptions. Figure 6 shows the structure of hub 4, hub 5 and hub 6 designed by SKF.Because the bearing assemblies are composed of outer ring, rolling balls, flangedshaft and inner ring, it is pivotal to adopt the swaging technology when assemblethem into a unit, thus itssignificant to develop the swaging technology for the shaftclinching assembly.Hub4Hub5Hub6Figure6 New generations of hub bearing unitIt is discovered by analyzing the conFigureuration of the hub bearing unit indetail that the number of parts of the hub unit can be further reduced with the swagingtechnology used in shaft clinching. The shaft end of theflanged inner ring may bedirectly swaged to raceway, and the smaller inner ring can be saved, then the parts ofthe unit are decreased. Thus it will predigest the structure of the hub unit, improve thereliability, reduce the cost of manufacture. One reason of this design is that thetightening position is not the weak point of the hub unit, but the root of the flangedinner ring. The other is informed by the FEM analysis that small inner ring receivesnot heavy axial load during the vehicle running, so the small inner ring can be saved.But before putting this project in practice, the key questions such as assembly of theballs, the dimension precision of the swaged raceway, the plastic deformation underheavy pressure must be solved.ReferencesReferencesReferencesReferences1 Junshi Sakamoto. Trends and New Technologies of Hub Unit Bearings.Motion &Control, 2005(17):292 T.NUMATA. Technical Trends of Automotive Wheel Bearings. KOYOEngineering Journal English Edition, 2003(162E):32363 Hirohide Ishida,Takeyasu Kaneko. Development of Hub Unit Bearing withSwaging. Motion &Control,2001(10):9144 K.TODA,T.ISHII,S.KASHIWAGI,T.MITARAI. Development of Hub Units withShaft Clinching for Automotive Wheel Bearings. KOYO Engineering Journal EnglishEdition,2001 (158):2630ContactContactContactContact Info:Info:Info:Info:Zhou ZhixiongProfessorCollege of Mechanical and Automotive EngineeringHunan UniversityHunan, ChangSha,410082 ChinaPhone:86-731-8821732 Fax:86-731- 8821732Email:Website: olling head and the centerline of workpiece. The roll-wheel swages theworkpiece, endures heavy force and serious attrition. Special material with thecapabilities to endure the force and attrition is adopted to manufacture the roll-wheel,and especial heat treatment is adopted to ensure the perfect strength and rigidity.毕业设计（论文）题目： 加速度过载模拟实验台设计院( 系 ) 航空与机械工程学院专业名称 机械设计制造及其自动化班级学号 078105234学生姓名 鄢驰指导教师 许瑛二O一一 年 六 月 毕业设计（论文）开题报告题目 加速度过载模拟实验台设计 专 业 名 称 机械设计制造及其自动化 班 级 学 号 078105234 学 生 姓 名 鄢驰 指 导 教 师 许瑛 填 表 日 期 2011 年 04 月 10 日一、选题的依据及意义：导弹等飞行器特别是对空发射等高质量、高精度的武器，它们有很高的要求：要有很好的机动性能，导弹的机动性能越好