专业英语1115Word文档格式.docx

专业英语1115Word文档格式.docx

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vertical[]垂直的

constant[]不变的

slippage[]滑动

inherent[]固有的

precise[]精确的

pulley[]滑轮

plane[]平面

wrap[]缠绕

Text:

Beltdrivesofferamaximumofversatilityaspowertransmissionelements.

Theyallowthedesignerconsiderableflexibilityinlocationofdriveranddrivenmachinery,andtolerancesarenotcriticalasisthecasewithgeardrives.

Anotheradvantageofbeltdrivesisthattheyreducevibrationandshocktransmission.

Furthermore,beltdrivesarerelativelyquiet.

Largeflatleatherbeltswereingeneralusemanyyearsago,whentheusualpracticewastouseonelargeenginetodriveseveraldifferentpiecesofmachinery.

Someleatherbeltsareinuseatthistimeaswellasflatsteel,rubber,plastic,andfabricbelts.

Light,thinflatbeltsarepracticalonhighspeedmachinerywherevibrationmaybeaproblem.

Vbeltsareprobablythemostcommonmeansoftransmittingpowerbetweenelectricmotoranddrivenmachinery.

ConventionalVbeltsaremadeofrubber.

Mostoften,bothdriveranddrivenpulleyslieinthesameverticalplane,andthespeedratioisconstant.

SmoothflatbeltsandVbeltsdependonfrictiononthepulleysandsomeslippageisinherentintheiroperation.

Therefore,speedratiosarenotprecise.

Mostheavydutypulleysaremadeofcastironorformedsteel.

Notethatthecapacityofthebeltdriveisdeterminedbytheangleofwrap,α,onthesmallerpulley,andthatthisisparticularlycriticalfordrivesinvolvingpulleysofgreatlydifferingsize,spacedcloselytogether.

Appending:

ConveyerBelt

Conveyer,mechanicalsystemfortransportingmaterialsfromonesitetoanother.Conveyersarewidelyusedinindustrialandbusinessoperations.Theyincludesimplechutes,theunpoweredrollerconveyersusedtomovecargoacrosssidewalksfromtruckstostores,andawiderangeofpoweredsystemsinwhichmaterialsarecarriedalongbybelt,bucket,screw,trolley,orotherarrangement.Pneumaticconveyersaretubesinwhichgoods—usuallyinafinelydividedform—aremovedalongbyblowers.AnimportantstepinautomationwasHenryFord'

sintroductionofpoweredconveyersintohisautomobileassemblylinein1913.

12.KeysandSprings

prevent[]防止

sprocket[]链齿轮

lever[]杆

flywheel[]飞轮

impeller[]叶轮

numerous[]许多

standardize[]使标准

square[]四方的

taper[]锥形,锥度

woodruffkey半圆键

hub[]轮毂

callfor要求

proportion[]比例

approximately[]近似地

diameter[]直径

exert[]施加

tensile[]拉力的

torsional[]扭转的

cantilever[]悬臂

elliptical[]椭圆的

washer[]垫圈

release[]释放

Keysareusedtopreventrelativemotionbetweenashaftandmachineelementssuchasgears,pulleys,sprockets,cams,levers,flywheels,impellers,andsoon.

Therearenumerouskindsofkey（someofwhichhavebeenstandardized）forvariousdesignrequirement.

Thekeysmostfrequentlyusedarethesquarekey,thetaperedkey,andthewoodruffkey.

Perhapsthemostcommonofthesetorque-transmittingshaft-to-hubconnectionsarekeys,ofwhichthemostcommontypeisthesquarekey.

Standardproportionscallforthekeywidthtobeapproximatelyone-forththeshaftdiameter.

Keysareusuallymadeofcold-finishedlow-carbonsteel,butheat-treatedalloysteelsareusedwhengreaterstrengthisrequired.

Mechanicalspringsareusedinmachinestoexertforce,toprovideflexibilityandtostoreortoabsorbenergy.

Ingeneral,springsmaybeclassifiedaseitherwirespringsorflatsprings,althoughtherearevariationswithinthesedivisions.

Wirespringsincludehelicalspringsofround,square,orspecial-sectionwireandaremadetoresisttensile,compressureortorsionalloads.

Underflatspringsareincludedthecantileverandellipticaltypes,theclocktypepower-springsandtheflatspringwashers,usuallycalledBellevillesprings.

Inoneword,springsareelasticmembersthatexertforces（ortorques）andabsorbenergy（whichisusuallystoredandlaterreleased）.

Springsareusually,butnotnecessarily,madeofmetal.

Plasticscanbeusedwhenloadsarelight.

1.Key

Key,inmechanics,smallpartfittingapreparedrecesscutintwojoinedpartsorcomponents,andthusemployedtolockthesepartstogether.Keysaremostcommonlyusedtolockwheelsorgearsfirmlyintheiraxles.Suchakeyisoftencomposedofathinstripofmetalthatfitstightlyintoatransversegroovecutintheaxleshaftandintoaparallelgrooveintheinnerdiameterofthewheelhub.Somekeysaredesignedtopreventanyplaybetweenwheelandaxle,andothersallowthewheeltoslidealongtheaxlebutnottoturnrelativetoit,althoughwhenslidingmotionisneeded,engineersusuallyprefertouseasplinedshaft.

2.Spring

Spring,inmechanics,devicemadeofanelasticmaterialthatundergoesasignificantchangeinshape,ordeformation,underanappliedload.Springsareusedinspringbalancesforweighingandforthestorageofmechanicalenergy,asinwatchandclockspringsordoor-closingsprings.Springsarealsousedtoabsorbimpact,asincoilorleafspringsusedforautomobilesuspensions,andtoreducevibrationbytheuseofrubberblocks.Thespecificformofaspringdependsonitsuse.Aweighingspring,forexample,isnormallywoundasahelix,anditselongationisproportionaltotheappliedforce,sothatthespringcanbecalibratedtomeasurethisforce.Watchspringsarewoundasspiralcoils,andsetsofflatbarsorleaves,superimposedononeanothertoformlaminations,areusedasleafspringsinautomobile.

13.Screw

screw[]螺钉

fastener[]扣件

wedge[]楔

circular[]圆形的

cylinder[]圆柱体

truncate[]截去顶端

cone[]圆锥体

moment[]力矩

groove[]凹槽

square[]正方，直角

hexagonal[]六边形的

wrench[]扳手

slot[]狭槽

recess[]凹处

screwdriver[]螺丝起子

oval[]椭圆的

fillister[]槽口

tap[]攻螺纹

capscrew帽螺钉

clamp[]夹紧

bolt[]螺栓

nut[]螺母

stud[]柱头螺栓

stretch[]伸长

tight[]拉紧的

setscrew固定（定位）螺丝

substitute[]替代品

conjunction[]联结

dimple[]微凹处

Screwshavebeenusedasfastenersforalongtime.

Asindicatedinthesectiononsinglemachines,ascrewactswithawedgingactionandconsistsofacircularcylinder（ortruncatedcone）withahelicalgrooveinit.

Whenusedforfastening,allscrewsareprovidedwithmeansforapplyingatorque（twistingmoment）tothem;

thismayconsistofasquareofhexagonalheadforawrench,aheadwithaslotoracross-shapedrecessforascrewdriver,acylindricalheadwitharecessfittingaspecialwrench,oraslotorrecessononeendfittingascrewdriverorspecialwrenchandnohead.

Screwswithscrewdriverslotshaveheadsofseveralshapes,suchasflat,oval,round,andfillister（cylindricalwitharoundtop）.

Woodscrewsaretapered,andself-tappingscrewshavetaperedendsandavarietyofspecialpoints.

Thelatterareusuallyhardenedandcutorformamatinginternalthreadwhenscrewedintothepropersizehole.

Screwswithhexagonalheadsareusuallyknownascapscrews.

Screwswithothertypesofheadsarealsoknownascapscrewsinthelargersizesandasmachinescrewsinthesmallsizes.

Allofthesescrewsareusedtoclampmachinepartstogetherwhenoneofthepartshasaninternalthread.

Ifneitherpartisthreadedaboltmustbeused:

thisconsistofascrewwithahexagonalhead,anut（hexagonalringwithaninternalthread）,andusuallyawasher（flatring）.

Astudhasthreadsonbothendsandnomeansforturning.

Itispermanentlyscrewedintoonememberandclampsbymeansofanutontheotherend.

Allofthesefastenersstretchwhentightened,andthetensileloadcreatedinthiswayclampsthememberstogether.

Setscrewsdifferinformandfunctionfromtheothertypeofscrews.

Theyarehardenedandhavecup,cone,oval,flat,anddog（cylindrical）endsorpoints.

Theyareusuallyheadlessandarefrequentlyusedassubstitutesforkeysorinconjunctionwithkeysinshaft-mountedmembers.

Thesetscrewfitsinathreadedradialholeinthehub,andthepointistighteneddownintoahole,aflat,oradimpleintheshaftorkey.

Setscrewsarestressedincompressionandinactiontheycreateahelicalwedgebetweentheconnectedparts.

CommonWoodScrews

Screw,mechanicalfasteningdeviceconsistsessentiallyofaninclinedplanewoundspirallyaroundacylinderoracone.Theridgesformedbythewindingplanesarecalledthreads,anddependingontheintendeduse,thethreadsmaybesquare,triangular,orroundedincrosssection.Thedistancebetweentwocorrespondingpointsonadjacentthreadsiscalledthepitch.Ifthethreadisontheoutsideofacylinder,itiscalledascrewormalethread,andifitisontheinsideofacylinder,asinthecaseofacommonnut,itiscalledafemalescrew.Screwsandboltsusedinmachinesemployacylindricalshaftwithaconstantinnerorminordiameter,butwoodscrewsandpipethreadsarecutonataperingcone.

14.Shafts

shaft[]转轴

component[]零件

deliver[]传送

crank[]曲柄

reciprocate[]往复