汽车紧固件与质量控制

质量控制主动质量控制从日常工作着手从小事做起质量控制流程的制定质量控制与设计试验同步利用现代质量管理技术手段(质量状态分析6,鱼刺图等)增强职工的质量管理意识(TQC)汽车紧固件紧固件种类螺栓螺帽(Bolt&Nut)螺钉(Screw)垫片(Washer)销子销键(Pin&Key)卡箍夹片(Clips&Push-Pins)捆扎条，固定带(Tie-Strap&Tape)粘合剂(Adhesives)紧固件的重要性(1)Thereareover1,200threadedfastenerjointsforaveragevehicle.Thismeansthatthereareover1,200opportunitiesforjoint-relatedfailures!紧固件的重要性(2)Ifwelackknowledgeofthreadedfastenerjointdesign,wecouldcontributetocustomerdis-satisfactionthatresultsfrom:Squeaks,rattles,andotherundesirablenoisesWarrantyrepairsFieldServiceActions(i.e.,recallsorcampaigns)紧固件的重要性(3)PoorthreadedfastenerjointdesignisamajorcontributortowarrantyOverdesignthatincreasesvehiclecostandweightErgonomicissuesintheassemblyplantUnachievableprocesscapabilityHighrepaircostsProgramdelays怎样合理的使用紧固件(ThreadedFastener)获得可靠的连接(Joint)？紧固件连接的基本原理:UltimatetensilestrengthYieldstrengthProofloadThecontactsurface,etc.功用:Attach(holdspartstogether)PositionProvidefordisassembly适用范围和环境紧固件扭矩的选择标准化以及表面处理紧固件扭矩的选择(1)紧固件扭矩的选择(2)Proofload:thehighesttensilestrengthaboltcanwithstandwithoutincurringanypermanentdeformation.Identifyingproofloadisthekeytoconsiderjointstrengthanddecidethetightentorque.Proofloadisgenerally90%ofthestressnecessarytocauseyield.Proofload=ClampLoad=NormalPressureForce紧固件扭矩的选择(3)Tightentorque=ProofLoadxKxDia.K=f(Geometry,FrictionCoefficient)Dia.=NominalDiameterThetorquefinalsettingsbyFastenerLabTorquetoyield/angletoturnTorquetoaspecifictorquenumberandhopeit'scorrect.Torquetomaximumstretchyield紧固件扭矩的选择(4)Darkblueislessthanonestandarddeviationfromthemean.Forthenormaldistribution,thisaccountsfor68%ofthesetwhiletwostandarddeviationsfromthemean(blueandbrown)accountfor95%andthreestandarddeviations(blue,brownandgreen)accountfor99.7%.NormalDistribution20Nmσ=1TorqueSpec=20±3NmTheGoldenRuleBecausedesigningareliablejointpresentssomanychallenges,therearemanychancesforerror.Avoidingtheuseofajointwhenitisnotneededreducesthechanceofjointfailure.Ifyoumustuseathreadedfastenerjoint,realizethatitiscomplexandmustbedesignedwithcare.