Safety clutch

Introduction

Thesafetyclutchismainlyusedfortheoverloadsafetyprotectionofthetransmissionsystem.Ofcourse,italsohasthecorrespondingclutchcharacteristicsofitsengagingelements.Designingorselectinganappropriatesafetyclutchcannotonlyensurethesafetyofthetransmissionsystem,butalsoimprovethetransmissionperformanceofthemachine.Thesafetyclutchisusuallyanormallyclosed(engaged)structure.Taketorqueastheoverloadprotectionparameter.

Therequirementsforthesafetyclutchare:flexibleandreliableaction,highworkingaccuracy,andlimittorquecanbeadjustedwithinacertainrange.

Accordingtothecharacteristicsoftheengagingelements,thesafetyclutchcanbedividedintotwotypes:meshingtypeandfrictiontype.Themeshingtypeusesjaws,steelballsandslidingpinsasjointelements;thefrictiontypemainlyincludesfrictionformssuchasdiscs,conesandcircumferences.

Themeshingsafetyclutchhasagreaterimpactduringengagementanddisengagement,andlong-termrepeatedclutchingiseasytodamagethepartsofthetransmissionshaftsystem,soitisnotsuitableforthedifferencebetweenthemainandfollowercombinedanddividedspeedsduringengagementandafterdisengagement.Largeplacesandplaceswithlargemomentsofinertiaonthedrivingsideordrivensideofthedecoupler-thefrictionsafetyclutchhasarelativeslidingfrictionprocessbetweentheplatformandtheseparationprocess,whichcanconsumepartoftheenergy,sotheengagementisstableandcaneasetheclutchTheshockcausedbytheinterruptionofthetransmissionduringtheseparation-Thefrictionsafetyclutchisoftenusedinplaceswherethespeeddifferencebetweenthemainandthedrivenpartsduringengagementandafterseparationislarge,andwherethereisanimpact:butthefrictionsafetyclutchisoff.Thereareshortcomingsofwearandheatduringtheclosingprocess.

Choiceofclutch

Forstandardclutch,pleaserefertotheselectionofcouplingfortheselectionofitstypeandmodel.Thebasicrequirementsthatshouldbemetwhenselectingaclutchare:reliableengagement,completeseparation,rapidaction,flexibleoperation,smoothandnoimpact;simplestructure,easymanufacturing,lowcost,safework,hightransmissionefficiency,longservicelife;lightweight,smallinertia,Smallsize,strongheatdissipationcapacity,convenientadjustmentandmaintenance,etc.Infact,itisverydifficulttomeettheaboverequirementsatthesametime.Generally,theselectionshouldbemadeaccordingtotheuserequirementsandworkingconditionstoensurethemainconditionsandtakeintoaccountotherconditions.Ifthespeedislow,thetorqueislarge,theworkisreliable,andthesizeissmall,theembeddedclutchcanbeselected.Ifthespeedishigh,thejointisstable,andthemainanddrivenshaftsdonotrequirecompletesynchronousrotation,thenthefrictionclutchcanbeselected.

Therearethreemaintypesofautomaticclutches.Thefirstisasafetyclutch,whichcanbeautomaticallyseparatedwhenthetransmittedtorquereachesacertainvalue;thesecondisacentrifugalclutch,whichusestheprincipleofcentrifugalforce,whentheshaftspeedreachesacertainspeed,itcanautomaticallyconnectorexceedItcanautomaticallydisengageafteracertainspeed;thethirdistheoverrunningclutch,whichcanonlyrotateinonedirection,andcanautomaticallydisengagewhenitrotatesinthereversedirection.

Shearpinsafetyclutch

AsshowninFigure1,thestructureofthisclutchissimilartoaflangecoupling,butwithoutbolts,itisconnectedbysteelpins.Thepinisputintothetwo-sectionsteelcasingthathasbeenquenched,andisshearedwhenoverloaded,sothatthetwoshaftsareseparated.

Becauseoftheunstablemechanicalpropertiesofthepinmaterialandtheerrorofthemanufacturingsize,thiskindofcouplinghaslowworkingaccuracy;andafterthepiniscut,theworkingcapacitycannotbeautomaticallyrestored,soitmustbestoppedforreplacementPin;butbecauseofitssimplestructure,itisoftenusedformachinesthatarerarelyoverloaded.

Ballsafetyclutch

Therearemanystructuralformsoftheballsafetyclutch.AsshowninFigure2,theclutchconsistsofthedrivinggear1,thedrivendisc2,theoutersleeve3,thespring4.Theadjustmentnutiscomposedof5.Thedrivinggear1islooselysleevedontheshaft,andtheoutersleeve3isconnectedwiththedrivendisc2byaspline,andatthesametimeisconnectedwiththeshaftbyakey.Intheendfacesofthedrivinggear1andthedrivendisk2,thereareanequalnumberofballsockets(generally4to8),whichareequippedwithballs.

Duringnormaloperation,duetothethrustofthespring4,theballsofthetwodiscsarepressedagainsteachotherinastaggeredmanner.AsshowninFigure3,thetorquetransmittedbythedrivinggearistransmittedthroughtheballs,thedrivendiscandtheoutersleeve.Tothedrivenshaft.Whenthetorqueexceedstheallowablevalue,thespringiscompressedbytheexcessiveaxialcomponentforce,whichcausesthedrivendisktomovetotheright,andtheballsslideovereachother.Atthistime,thedrivingwheelisidling;whentheloadreturnstonormal,thetorquecanbetransmittedagain.Thesizeofthespringpressurecanbeadjustedwithnut5.

Thiskindofclutchisgenerallyonlyusedindevicesthattransmitsmalltorqueduetosevereimpactandwearontheballsurface.