机械工程专业英语课件--L05.ppt

English for Mechanical Engineering机械工程专业英语常州工学院机电工程学院徐红丽机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background InformationnMetalMaterials(金属材料金属材料)Therearemanydifferentmaterialtypestochoosefromwhenundertakingaproject.Inmatierialscience,thematerialsaregroupedroughlyintotwocategories,thesebeingNon-metallicandMetallic.Inrespecttometallicmaterialsthesearethensubsequentlygroupedintotwogroupsbeingferrousandnon-ferrous.Eachofthematerialshastheirowncharacteristicsandrequiresdifferentmachiningtechniques.Carefulconsiderationneedstobegiventothecorrectmaterialselectionforitsapplication.(Definition:FerrousasincontainingIron,e.gsteel-Non-ferrousasinnotcontainingIrone.galuminium,copper)Asimpletestforferrous/non-ferrousmaterialsistousemagnetasamagnetwillsicktoferrousmaterialsduetoitsironcontent.Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background InformationnAluminiumAlloy TherearemanykindsofAlloystochoosefrombutoften,Aluminiumischosenasitislightweight(about2700kg/m3density),itiscomparativelysoftanditsprocess-abilityisgood.FromamachiningviewpointpurealuminiumgreatlydiffersfromAl-Cualloy。Purealuminiumiseasytobendbutitisdifficulttoprocessasitistoosoftandeasilyclogscuttingtools.Ontheotherhand,theAl-Cualloyiseasytohandleandcutwithseveralofthegradeshavingstrengthsimilartothatofsteel.However,oneofthedrawbacksofaluminiumisthatitisdifficulttoweld,solderandbend.Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background InformationnCarbonSteelTypicalcarbonsteelmaterialsareverycheap,excellinginweldability,andtheycanbesubjectedtovariousheattreatments.Sincemanymachinetoolsaredesignedtocutmildsteelmaterial,itisveryraretoencounterproblemswhilemachining.Generally,mildsteelhasablacksurfaceandthissurfaceisveryhard,ifpossible,thissurfaceshouldbeleftintactasitoffersadditionalprotection.Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background InformationnCommonShapesMaterialisusuallysuppliedascommonshapesandtheseare(a)Billets(columns),(b)flatbar(boards),(c)Angle(L-shaped),(d)Cchannel(C-shaped)and(e)pipe.Thecorrectselectionofmaterialassistsinsimplifyingaproject.Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background InformationnNon-metal Lesson5MetallicandNonmetallicMaterials Thereisnorigorousdefinitionforthetermnonmetal-itcoversageneralspectrumofbehaviour.Commonpropertiesconsideredcharacteristicofanonmetalinclude:lpoorconductorsofheatandelectricitywhencomparedtometalsltheyformacidicoxides(whereasmetalsgenerallyformbasicoxides)linsolidform,theyaredullandbrittle,ratherthanmetalswhicharelustrous,ductileormalleablelusuallyhavelowerdensitiesthanmetalsltheyhavesignificantlylowermetalingpointandboilingpointsthanmetalslnon-metalshavehighelectronegativitymlibladj.可锻造的可锻造的,有延展有延展性的，韧性的性的，韧性的Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语stress应力应力strain应变应变density密度密度strength强度强度hardness硬度硬度rigidity刚度刚度elasticity弹性弹性plasticity（ductility）塑性塑性toughness韧性韧性compression压缩压缩tension拉伸拉伸bend弯曲弯曲torsion扭转扭转shear剪切剪切fatigue疲劳疲劳deformationn.变形变形metalformingprocessn.金属成型工艺（过程金属成型工艺（过程)词词 汇汇机械工程专业英语机械工程专业英语课文分析课文分析Perhapsthemostcommonclassificationthatisencounteredinmaterialsselectioniswhetherthematerialismetallicornonmetallic.Thecommonmetallicaresuchmetalsasiron,copper,aluminum,magnesium,nickel,titanium,lead,tin,andzincandthealloysofthesemetals,suchassteel,brass,andbronze.Theypossessthemetallicpropertiesofluster,thermalconductivity,andelectricalconductivity;arerelativelyductile;andsomehavegoodmagneticproperties.Thecommonnonmetalsarewood,brick,concrete,glass,rubber,andplastics.Theirpropertiesvarywidely,buttheygenerallytendtobelessductile,andlessdensethanthemetals,andtheyhavenoelectricalconductivityandpoorthermalconductivity.Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析Perhapsthemostcommonclassificationthatisencounteredinmaterialsselectioniswhetherthematerialismetallicornonmetallic.Thecommonmetallicmaterialsaresuchmetalsasiron,copper,aluminum,magnesium,nickel,titanium,lead,tin,andzincandthealloysofthesemetals,suchassteel,brass,andbronze.在材料选择时所遇到的最普通的分类问题，可在材料选择时所遇到的最普通的分类问题，可能就是这种材料是金属材料还是非金属材料。能就是这种材料是金属材料还是非金属材料。最常见的金属材料如铁，铜，铝，镁，镍，钛，最常见的金属材料如铁，铜，铝，镁，镍，钛，铅，锡和锌以及这些金属的合金，例如钢，黄铜铅，锡和锌以及这些金属的合金，例如钢，黄铜和青铜。和青铜。mni:zjmn.镁镁taiteinimn.钛钛Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析Theypossessthemetallicpropertiesofluster,thermalconductivity,andelectricalconductivity;arerelativelyductile;andsomehavegoodmagneticproperties.他们具有金属特性：光泽，导热性和导他们具有金属特性：光泽，导热性和导电性，一定的延展性，而某些金属还具有电性，一定的延展性，而某些金属还具有良好的磁性。良好的磁性。Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析Thecommonnonmetalsarewood,brick,concrete,glass,rubber,andplastics.常用非金属材料有木头，砖，混泥土，玻璃，常用非金属材料有木头，砖，混泥土，玻璃，橡胶和塑料。橡胶和塑料。Theirpropertiesvarywidely,buttheygenerallytendtobelessductile,andlessdensethanthemetals,andtheyhavenoelectricalconductivityandpoorthermalconductivity.他们的性能变化很大，但它们通常几乎没有延展他们的性能变化很大，但它们通常几乎没有延展性，比金属疏松，而且它们不具有导电性以及有较性，比金属疏松，而且它们不具有导电性以及有较差的导热性。差的导热性。Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析Althoughitislikelythatmetalsalwayswillbethemoreimportantofthetwogroups,therelativeimportanceofthenonmetallicgroupisincreasingrapidly,andsincenewnonmetalsarebeingcreatedalmostcontinuously,thistrendiscertaintocontinue.Inmanycasestheselectionbetweenametalandnonmetalisdeterminedbyaconsiderationofrequiredproperties.Wheretherequiredpropertiesareavailableinboth,totalcostbecomesthedeterminingfactor.Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析Althoughitislikelythatmetalsalwayswillbethemoreimportantofthetwogroups,therelativeimportanceofthenonmetallicgroupisincreasingrapidly,andsincenewnonmetalsarebeingcreatedalmostcontinuously,thistrendiscertaintocontinue.虽然两大类材料中，金属材料可能总是更加重虽然两大类材料中，金属材料可能总是更加重要，但非金属材料的相对重要性在迅速增强，由于要，但非金属材料的相对重要性在迅速增强，由于新的非金属材料几乎是在不断地产生，并且这一趋新的非金属材料几乎是在不断地产生，并且这一趋势将确定无疑地继续下去。势将确定无疑地继续下去。Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析Inmanycasestheselectionbetweenametalandnonmetalisdeterminedbyaconsiderationofrequiredproperties.许多情况下选择金属材料还是非金属，是许多情况下选择金属材料还是非金属，是考虑所需要材料的性能来确定的。考虑所需要材料的性能来确定的。Wheretherequiredpropertiesareavailableinboth,totalcostbecomesthedeterminingfactor.两种材料的性能都能满足需要的时候，总成两种材料的性能都能满足需要的时候，总成本就成了决定性的因素。本就成了决定性的因素。Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析Onematerialcanoftenbedistinguishedfromanotherbymeansofphysicalproperties,suchascolor,density,specificheat,coefficientofthermalexpansion,thermalandelectricalconductivity,magneticproperties,andmeltingpoint.Someofthese,forexamplethermalconductivity,electricalconductivity,anddensity,maybeofprimeimportanceinselectingmaterialforcertainspecificuses.Thosepropertiesthatdescribehowamaterialreactstomechanicalusage,however,areoftenmoreimportanttotheengineerinselectingmaterialsinconnectionwithdesign.Thesemechanicalpropertiesrelatetohowthematerialwillreacttothevariousloadingduringservice.Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析Onematerialcanoftenbedistinguishedfromanotherbymeansofphysicalproperties,suchascolor,density,specificheat,coefficientofthermalexpansion,thermalandelectricalconductivity,magneticproperties,andmeltingpoint.通常借助于物理性质来区别一种材料和另一种材通常借助于物理性质来区别一种材料和另一种材料，例如颜色、密度、比热、热膨胀系数、导热料，例如颜色、密度、比热、热膨胀系数、导热性、导电性、磁性和熔点。性、导电性、磁性和熔点。不同于不同于;与与加以区别加以区别 kuifintn.系数系数,率率,程程度度;Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析Someofthese,forexamplethermalconductivity,electricalconductivity,anddensity,maybeofprimeimportanceinselectingmaterialforcertainspecificuses.有些性能，象导热性、导电性和磁性，对于某些有些性能，象导热性、导电性和磁性，对于某些特定场合来说，在选择材料时可能是极其重要的。特定场合来说，在选择材料时可能是极其重要的。Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析Thosepropertiesthatdescribehowamaterialreactstomechanicalusage,however,areoftenmoreimportanttotheengineerinselectingmaterialsinconnectionwithdesign.Thesemechanicalpropertiesrelatetohowthematerialwillreacttothevariousloadingduringservice.描述一种材料在机械应用中表现出的性能，对于工描述一种材料在机械应用中表现出的性能，对于工程师在设计中选择材料来说，往往更为重要。程师在设计中选择材料来说，往往更为重要。这些机械性能关系到材料在实际应用中对于各种这些机械性能关系到材料在实际应用中对于各种载荷的反应。载荷的反应。Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析Mechanicalpropertiesarethecharacteristicresponsesofamaterialtoappliedforces.Thesepropertiesfallintofivebroadcategories:strength,hardness,elasticity,ductility,andtoughness.机械性能是材料对所施加的作用力的特性反应。机械性能是材料对所施加的作用力的特性反应。这些性能主要分为五大类：强度、硬度、弹性、这些性能主要分为五大类：强度、硬度、弹性、塑性和韧性。塑性和韧性。ilstisitin.弹力弹力,弹性弹性Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析1.Strengthistheabilityofamaterialtoresistappliedforces.Elevatorcablesandbuildingbeamsallmusthavethisproperty.2.Hardnessistheabilityofamaterialtoresistpenetrationandabrasion.Cuttingtoolsmustresistabrasion,orwear.Metalrollsforsteelmillsmustresistpenetration.1、强度：是材料抵抗外力作用的能力。升降机的、强度：是材料抵抗外力作用的能力。升降机的钢丝绳和建筑物的横梁都必须具备这种性能。钢丝绳和建筑物的横梁都必须具备这种性能。2、硬度：是材料抵抗穿透和磨损的能力。剪切工、硬度：是材料抵抗穿透和磨损的能力。剪切工具必须能耐磨和抗磨损。轧钢机上的金属轧辊必具必须能耐磨和抗磨损。轧钢机上的金属轧辊必须能抗穿透。须能抗穿透。轧钢厂轧钢厂penitreinn.穿透穿透,突破突破eliveitn.电梯电梯,升升降机降机Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析3.Elasticityistheabilitytospringbacktooriginalshape.Allspringsshouldhavethisquality.4.Ductilityistheabilitytoundergopermanentchangesofshapewithoutrupturing.Stampedandformedproductsmusthavethisproperty.3、弹性：是材料恢复原形的能力。所有的弹簧都、弹性：是材料恢复原形的能力。所有的弹簧都应具备这种性质。应具备这种性质。4、塑性：材料承受永久变形而无裂损的能力。冲、塑性：材料承受永久变形而无裂损的能力。冲压和成型产品必须具备这种性能。压和成型产品必须具备这种性能。Lesson5MetallicandNonmetallicMaterials 机械工程专业英语机械工程专业英语课文分析课文分析5、韧性：是材料吸收所施力的机械能的能力。强度、韧性：是材料吸收所施力的机械能的能力。强度和塑性决定着材料的韧性。火车车厢、汽车车桥、和塑性决定着材料的韧性。火车车厢、汽车车桥、锤子以及类似的产品都需要有韧性。锤子以及类似的产品都需要有韧性。5.Toughnessistheabilitytoabsorbmechanicallyappliedenergy.Strengthandductilitydetermineamaterialstoughness.Toughnessisneededinrailroadcars,automobileaxles,hammers,andsimilarproducts.Lesson5MetallicandNonmetallicMaterials