ConstructionandSolutiontoaNewDynamicModelofF orgingHammersDampingSystem¥LIUGang;CHENWeim in;CHENWei(刘钢,陈维民,陈威)(Dept.ofMaterialScienc eandEngineering,HarbinInstituteofTechnology ,Harbin,150001,China)Abstract:Forthedirectl ysupportedisolatedfoundationwhichincludesre turningisolator,anewdynamicmodelofforgingha mmersdampingsystemisfounded.Thissystemissol vedbymodelanalysistogetasetofnewcalculating formulasaboutthevibrationparametersofanvila ndfoundation.Keywords:Forginghammer,damping system,dynamicmodel0INTRODUCTIONForginghamm erswillproduceviolentshockandinduceseriouss ocialharmofvibrationwhentheyareworking[1].T herefore,itisveryimportanttosolvetheproblem ofthevibrationresultingfromforginghammers.A tpresent,thedirectlysupportedisolatedfounda tionisappliedmostfrequentlyF[2,3].Itsstruct ureisshowninFig.1.Theanvilofforginghammeris mountedonresilientfoundationandthereturning isolatorissettocontrolthespring-backofanvil .Thiskindofisolatedfoundationhassomeadvanta gesasfollows:itsstructureissimpleanditneeds lessinvestment.Itenablesustoisolatevibratio nforthelargeamountofexistinghammerequipment swithoutreconstructionoffoundations.Fig.1Is olatingfoundationsupporteddirectly[2]Accord ingtothecharacteristicsofthiskindofdirectly supportedisolatedfoundation,anewtwo-degree- of-freedomdynamicmodel(2DFDM)withdampingisf oundedsothattheoptimumdesignofforginghammer isolatingsystemcanbeperformed.1FOUNDINGOFNE WDYNAMICMODELInthepaper,2DFDMwithdampingisa pplied.Comparedwithmosttraditionalmodels,th isisclosertotheactualsituationandhasbetterc alculatingprecision,inaddition,itismoreconv enienttocarryoutcomputeraidedvibrationanaly sisonthismodel.Thetraditional2DFDMwithdampi ngusedinformerresearchesisshowninFig2.Inthi smodel,theanvilandthefoundationareregardeda stworigidparticles.Meanwhile,thepatunderthe anvilandthegroundunderthefoundationareregar dedasthecombinationoflinearspringandviscous damping.Throughresearchformanyyears,therese archersofHarbininstituteofTechnologyhavefou ndthatthespring-backamplitudeoftheanvilincr easeswiththedecreaseofthepadstiffness,andth isinturnisliabletoinfluencetheworkofthework ersandtheautomaticdeliverymachines.Sotheanv ilreturningisolator(component3inFig.1)mustb eusedtocontroltheamplitudeofanvilvibrationa ndquickentheattenuationofanvilvibration.Ver ifiedbyactualexperience,thereturningisolato rdoesplayanimportantrole.However,thesetting ofreturningisolatorhasneverbeentheoreticall yanalyzeddeeply.Theselectionofthestiffnessa ndthedampJngratioofreturningisolatorhasneve rbeencalculatedthoroughly,andtheisolatorisd esignedbyexperience.Asaresult,suchdesignwou ldbedifficulttoattainthebestisolatingeffect .Inthispaper,withtheconsiderationoftheeffec tofreturningisolator,anewdynamicmodelisfoun dedandshowninFig.3andFig.4.ThemodelinFig.3i s2DFDMwithdamping,andthemodelinFig.4is2DFDM withoutdamping.InthedynamicmodelshowninFig. 3,theanvilandthefoundationareregardedastwor igidparticlesm1andm2.Meanwhile,thereturning isolator,thepatundertheanvilandthegroundund erthefoundationareallregardedasthecombinati onoflinearspringandviscousdamping.Thestiffn essoflinearspringsarek1,k2andk3respectively .Theviscousdampingcoefficientsarec1,c2andc3 respectively.Fig.22DFDMwithdampingandwithou treturningisolatori|4 ̄6|Fig.32DFDMwithdampi ngandreturningisolator[7]Fig.42DFDMwithoutd ampingandwithreturningisolator|7|2CONSTRUCT IONANDSOLUTIONOFTHEKINEMATICEQUATIONSForthe newvibrationdynamicmodel,asetofnewvibration analyticalequationswillbefoundedtogettheexp ressionofeachvibrationparameterofforgingham mer.Byusing.theNewtoniansecondlaw,asetofkin ematicdifferentialequationsforthe2DFDMwithd arnping(showninFig.3)isfoundedasfollows:2.1 SolutiontotheTwo-degree-of-freedomSystemwit houtDampingForsimplifyingthecalculatingproc ess,thevibrationmatrixoftwo-degree-of-freed omsystemwithoutdampingshouldbesolvedatfirst .ItsdynamicmodelisshowninFig.4,thenthekinem aticequationsare:synchronousmotioncanbeassu med,thatis,thetwokinematicequationsofdifferentcoordinateshavethesametimefunction,butonlydifferentinamplitudes.Then,x1andx2canbedefinedbyx1=Aest,x2=Best.Substitutingthemandt
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