外文原文GEARSGEARSAREVITALFACTORSINMACHINERY,WHICHAREUSESTOTRANSMITPOWERORMOTIONFROMONESHAFTTOANOTHERTHEYMAYBEUSEDONLYTOTRANSMITMOTIONFROMONEPARTOFAMACHINETOANOTHER,ORTHEYMAYBEUSEDTOCHANGETHESPEEDORTHETORQUEOFONESHAFTWITHWITHRELATIONTOANOTHERONEOFTHEFIRSTMECHANISMINVENTEDUSINGGEARSWADTHECLOCKINFACT,ACLOCKISLITTLEMORETHANATRAINOFGEARSCONSIDERABLESTUDYANDRESEARCHHAVEBEENMADEONGEARSINRECENTYEARSBECAUSEOFTHEIRWIDEUSEUNDEREXACTINGCONDITIONSTHEYHAVETOTRANSMITHEAVIERLOADSANDRUNATHIGHSPEEDSTHANEVERBEFORETHEENGINEERSANDTHEMACHINISTSALLCONSIDERGEARINGTHEPRIMEELEMENTINNEARLYALLCLASSESOFMACHINERYSUPERGEARSSPURGEARSWILLBECONSIDEREDFIRSTFORSEVERALREASONSINTHEFIRSTPLACE,THEYARESIMPLESTANDTHELEASTEXPENSIVEOFGEARSANDTHEYMAYBEUSEDTOTRANSMITPOWERBETWEENPARALLELSHAFTS,ALSO,SPURGEARSDEFINITIONSAREUSUALLYAPPLICABLETOOTHERTYPESITISIMPORTANTGOUNDERSTANDTHEFOLLOWINGDEFINITIONS,SINCETHEYAREIMPORTANTFACTORSINTHEDESIGNOFANYEQUIPMENTUTILIZINGGEARSDIAMETRICPITCHTHENUMBEROFTEETHPERINCHOFPITCHCIRLEDIAMETERTHEDIAMETERPITCHISUSUALLYANINTEGERASMALLNUMBERFORTHEPITCHIMPLIESALARGETOOTHSIZEMESHINGSPURGEARSMUSTHAVETHESAMEDIAMETERPITCHTHESPEEDRATIOISBASEDONTHEFACTTHATMESHINGGEARSMAYHAVEDIFFERENTSIZEDPITCHCIRCLESANDHENCEDIFFERENTNUMBEROFTEETHCIRCULARPITCHTHEDISTANCEFROMAPOINTONONETOOTHTOTHECORRESPONDINGPOINTONANADJACENTTOOTH,MEASRUEDALONGTHEPITCHCIRCLETHISISALINERDIMENSIONANDTHUSBASLINERUNITSPITCHCIRCLETHECIRCLEONWHICHTHERATIOOFTHEGEARSETISBASED,WHENTWOGEARSAREMESHING,THETWOPITCHCIRCLESMUSTBEEXACTLYTANGENTIFTHEGEARSARETOFUNCTIONPROPERLYTHETANGENCYPOINTISKNOWNASTHEPITCHPOINTPRESSUREANGLETHEANGLEBETWEENTHELINEOFACTIONANDALINEPERPENDICULARTOTHECENTERLINESOFTHETWOGEARSINMESINGPRESSUREANGLESFORSPURGEARSAREUSUALLY145OR20DEGREES,ALTHOUGHOTHERVALUESCANBEUSEDMESHINGGEARSMUSTHAVETHESAMEPRESSUREANGLESINTHECASEOFARACK,THETEETHHAVETHESTRAIGHTSIDESINCLINEDATANANGLECORRESPONDINGTOTHEPRESSUREANGLEBASECIRCLEACIRCLETANGENTTOTHELINEOFACTIONORPRESSURELINETHEBASECIRCLEISTHEIMAGINARYCIRCLEABOUTWHICHANINVOLUTESCUREISDEVELOPEDMOSTSPURGEARSFOLLOWANINVOLUTESCUREFROMTHEBASECIRCLETOTHETOPOFTHETOOTCH,THISCURECANBEVISUALIZEDBYOBSERVINGAPOINTONATAUTCORDANITISUNWOUNDFROMACYLINDERINAGEAR,THECYLINDERISTHEBESTCIRCLEADDENDUMTHERADIALDISTANCEFORMTHEPITCHCIRCLETOTHETOPOFTHETOOTHDEDENDUMTHERADIALDISTANCEFROMFILEPITCHCIRCLETOTHEROOTOFTHETOOTHCLEARANCETHEDIFFERENCEBETWEENTHEADDENDUMANDTHEADDENDUMFACEWIDTHTHEWIDTHOFTHETOOTHMEASUREDAXIALLYFACETHESURFACEBETWEENTHEPITCHCIRCLEANDTHETOPOFTHETOOTHFLANKTHESURFACEBETWEENTHEPITCHCIRCLEANDTHEBOTTOMOFTHETOOTHHELICALGEARSTHESEGEARSHAVETHEIRTOOTHELEMENTATANANGLEORHELIXTOTHEAXISOFTHEGEARTHEYAREMOREDIFFICULTANDEXPENSIVETOMAKETHANSPURGEARS,BUTAREQUIETERANDSTRONGERTHEYMAYBEUSEDTOTRANSMITPOWERBETWEENPARALLELSHAFTSATANANGLETOEACHINTHESAMEORDIFFERENTPLANESHERRINGBONEGEARSAHERRINGBONEGEARISEQUIVALENTTOARIGHTHANDANDALEFTHANDHELICALGEARPLACEDSIDEBYSIDEBECAUSEOFTHEANGLEOFTHETOOTH,HELICALGEARSCREATECONSIDERABLESIDETHRUSTONTHESHAFTAHERRINGBONEGEARCORRECTSTHISTHRUSTBYNEUTRALIZINGIT,ALLOWINGTHEUSEOFASMALLTHRUSTBEARINGINSTEADOFALARGEONEANDPERHAPSELIMINATINGONEALTOGETHEROFTENACENTRALGROOVEISMADEROUNDTHEGEARFOREASEINMACHININGBEVELGEARSBEVELGEARSAREUSEDTOCONNECTSHAFTS,WHICHARENOTPARALLELTOEACHOTHERUSUALLYTHESHAFTSARE90DEGTOEACHOTHER,BUTTHEYMAYBEMOREORLESSTHAN90DEGTHETWOMESHINGGEARSMAYHAVETHESAMENUMBEROFTEETHFORTHEPURPOSEOFCHANGINGDIRECTIONOFMOTIONONLY,ORTHEYMAYHAVEADIFFERENTNUMBEROFTEETHFORTHEPURPOSEOFCHANGINGBOTHSPEEDANDDIRECTIONTHEFACESOFTHETEETHLIEONTHESURFACEOFTHEFRUSTUMOFACONE,THEREFORETHETEETHELEMENTSARENOTPARALLELTOEACHOTHERITCANBESEENTHATTHISLACKOFPARALLELISMCREATESAMACHININGPROBLEMSOTHATTWOPASSESWITHATOOLMUSTBEMADETHETOOTHELEMENTSMAYBESTRAIGHTORSPIRAL,SOTHATWEHAVEPLAINANTISPIRALEVELGEARSWORMANDWORMGEARSAWORMANDWORMGEARCOMBINATIONISUSEDCHIEFLYWHEREITISDESIREDTOOBTAINAHIGHGEARREDUCTIONINALIMITEDSPACE,NORMALLYTHEWORMDRIVERSTHEWORMGEARANDISNOTREVERSIBLE,THATISTOSAY,THEWORMGEARCANNOTDRIVETHEWORMMOSTWORMSCANBEROTATEDINEITHERDIRECTION,CLOCKWISEORCOUNTERCLOCKWISERACKSARACKISAGEARWITHANINFINITERADIUS,ORAGEARWITHITSPERIMETERSTRETCHEDOUTINTOASTRAIGHTLINEITISUSEDTOCHANGERECIPROCATINGMOTIONTOROTARYMOTIONORVICEVERSAALATHERACKANDPINIONISAGOODEXAMPLEOFTHISMECHANISMVARIOUSMATERIALSAREUSEDINMANUFACTURINGGEARSUSUALLY,THEMATERIALSSELECTEDDEPENDSONTHEMETHODUSEDFORMAKINGTHEGEARANDTHEAPPLICATIONTOWHICHITWILLBEPUTGEARSCANBECAST,CUT,OREXTRUDEDTYPICALMATERIALSINCLUDECASTIRON,CASTSTEEL,PLAINCARBONSTEEL,ALLOYSTEELALUMINUM,PHOSPHORBRONZE,LAMINATEDPHONETICS,ANDNYLON中文翻譯齒輪齒輪是機(jī)器中的動(dòng)力元件,用來(lái)傳遞軸與軸之間的運(yùn)動(dòng)及動(dòng)力。它們可能僅被用來(lái)傳遞運(yùn)動(dòng),即機(jī)器的一個(gè)部分到另一個(gè)部分,或者被用來(lái)改變軸與軸之間相對(duì)速度和轉(zhuǎn)矩,第一個(gè)被發(fā)現(xiàn)用齒輪的機(jī)器是鐘表,事實(shí)上,鐘表的齒輪與火車(chē)上的齒輪相比是非常小的。由于齒輪在實(shí)際環(huán)境中的廣泛應(yīng)用,人們?cè)邶X輪的應(yīng)用方面進(jìn)行了許多的研究和調(diào)查?，F(xiàn)在,齒輪傳動(dòng)比起以前來(lái)不得不傳遞很重的載荷,和在高速度下運(yùn)轉(zhuǎn)。目前工程師和機(jī)械師都在考慮存在于機(jī)械中的這種因素。直齒圓柱齒輪直齒圓柱齒輪被作為傳動(dòng)中的首選有許多原因。它們是最簡(jiǎn)單也是最廉價(jià)的，并且它們可以被用作傳動(dòng)平行軸之間的力，還有它的概念同于其它類(lèi)型的齒輪，以下的幾個(gè)定義是非常重要的，因?yàn)椋鼈冊(cè)谠O(shè)計(jì)任何與齒輪有關(guān)的方面都是非常重要的。徑節(jié)節(jié)圓直徑單位距離上的齒數(shù)，徑節(jié)通常是一個(gè)整數(shù)。小小的一段齒距包括了許多的齒形。直齒圓柱齒輪嚙合的條件是必須有相同的徑節(jié)，齒輪的傳動(dòng)比決定于嚙合齒輪的不同的節(jié)圓和不同數(shù)目的齒數(shù)。齒距沿著節(jié)圓從齒上的一點(diǎn)到臨近齒上對(duì)應(yīng)相同的另一點(diǎn)的距離，這是一個(gè)線(xiàn)尺寸和線(xiàn)性單位。節(jié)圓作為齒輪比率設(shè)定基礎(chǔ)的圓。若要是互相嚙合的齒輪正常運(yùn)行，則兩節(jié)圓必須精確相切。壓力角運(yùn)動(dòng)方向與垂直于兩嚙合齒輪中心線(xiàn)的直線(xiàn)所形成的夾角。對(duì)于直齒圓柱齒輪壓力角為145度或20度，因此可以有許多的用途，相嚙合的齒輪必須有相同的壓力角。對(duì)于齒條，齒相對(duì)于直邊有與壓力角相同的傾斜角度?；鶊A與運(yùn)動(dòng)方向相切（或與壓力角方向相切）的圓?；鶊A是產(chǎn)生漸開(kāi)線(xiàn)所假想的圓。許多直齒圓柱齒輪都是漸開(kāi)線(xiàn)從基圓到齒頂，當(dāng)繃緊繩索從一個(gè)圓柱體展開(kāi)時(shí)，仔細(xì)觀察繩索上某點(diǎn)的運(yùn)動(dòng)，即可想象出此段漸開(kāi)線(xiàn)的形狀。在齒輪中，基圓是最主要的圓。齒頂高從節(jié)圓到齒頂?shù)膹较蚓嚯x。齒根高從節(jié)圓到齒底的徑向距離。間隙齒頂高與齒根高之間的不同。面寬齒在軸向的寬度。面節(jié)圓和齒頂之間的表面。齒腹節(jié)圓和齒底之間的表面。斜齒輪這些齒輪的齒相對(duì)于齒輪軸線(xiàn)由一個(gè)角度或螺旋角度，它們比直齒圓柱齒輪的制造更難，造價(jià)更昂貴，但是它們傳動(dòng)無(wú)噪音并且可靠。它們可以用來(lái)在相同或不同平面中構(gòu)成一定角度的相兩軸之間的力的傳遞。人字形齒輪人字形齒輪是在齒輪兩邊有相同數(shù)量在左旋和右旋形的齒輪。由于齒輪有角度，齒輪制造時(shí)需要考慮軸受到的軸向力，人字形齒輪是用平衡的方法來(lái)抵消軸向推力的，固而允許選用輕系列軸承取代重系列軸承，甚至可以完全取消軸承，通常在切削加工中在齒輪的周?chē)幸粋€(gè)中心槽來(lái)抵消。錐齒輪錐齒輪用作互相不平行的軸之間的連接。通常軸之間的夾角是90度，但它們比90多或少，相嚙合的兩齒輪僅改變運(yùn)動(dòng)方向，或者為改變速度具有不同的齒數(shù)，齒的表面沿著圓錐的