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1、张新房专业英语阅读f教案x(Part II:Metal-Casting Processes and Equipment金属铸造工艺与设备In this part,some important and fundamental knowledge about casting must beunderstood.For this chapter,we should know the differences of Chinese meanings forthese professional English words,and I will address these important parts.F
2、orming:成型 Ornament:装饰物Molding:造型 Intricate:复杂的Powder metallurgy:粉末冶金 Hollow:中空的Pouring:浇注Fig.II.1 Cast parts in a typical automobile 图 2.1 一个典型的汽车中的铸造部件Water pump:水泵 Lettering:编字码Pulley:滑轮 Differential housing:差速机壳Grill:栅栏 Transmission housing:变速机壳Intake and exhaust manifold:进气和排 Engine block:汽缸体气管
3、Carburetor:化油器Disk brake:刹车片 Piston:阳模Brake drum:制动鼓 Alternator housing:同步发电机壳Brake cylinder:闸缸Fig.IL 2.Outline of metal-casting processes described in part II.ShellExpandable patternPlasterCeramicPressureDieCentrifugalSqueezeSingle-crystalturbine bladesDirectionalsolidificationInvestmentSemisolid定向
4、凝固锻压离心挤压半凝固消耗性的图形高聚物陶瓷围模料图II.2.在第二章中所描述的金属铸造工艺概要Chapter 10 Fundamentals of Metal-Casting金属铸造基础For this chapter,it was divided into these parts:1.Introduction:简介2.Solidification of metals:金属的凝固3.Fluid flow:流体流动4.Fluidity of molten metal:熔融金属的流动性5.Heat transfer:热传递6.Defects:缺陷First,1.IntroductionThe c
5、asting process basically involves three steps:a.pouring molten metal into a mold patterned after the part to be manufactured;（把熔融金属浇注到加工好的模具型腔）b.allowing it to cool and solidify（冷却和凝固）c.removing the metal from the mold（从模具中取出金属）As we know,the casting is the oldest process to manufacture part of tool
6、 in the humanbeings history,because it has many advantages compared with other manufacturedprocesses as follows:/complex shapes,such as differential housing（差速机壳）used in the automobile,crankshaft（曲轴）and so on;/Very large part,such as engine housing used in the ship making./Utilize the work pieces th
7、at other manufactured processes can not produce ofuneconomic,such as turbine blade（涡轮机叶片）.So,it is essential for us to understand the fundamentals of metal casting by studyingthis book hard.There are some important considerations in the casting operation as follows:令 The flow of the molten metal int
8、o the mold cavity:熔融金属流入模具型腔,Fluidity.令 The cooling and solidification of metal in the mold:金属在模具中的冷却和凝SI:heat transfer:热传导.令 The influence of different type of mold materials,different heat transferringability,不同的模具材料具有不同的热传导能力.In this part,we talked about some introductions of metal casting;in the
9、 next,we willtalk the second part:solidification of metals.2.Solidification of metalsAs we know,for different metals,such as pure metals and alloys,the solidificationprocesses are different,so they will be divided into pure metal and alloy to bediscussed different solidification processes.1,Pure met
10、alsFor pure metal,the melting point is constant,so,the solidification is like this one:熔化潜热After reaching melting pointRelease of latentheat of fusionsolidification from interface and thento center with different grain type and size/Chill zone（a）J /Columnar zoneEquiaxed（c）struciureFig.10.1 Schematic
11、 illustrationof three caster structure ofmetals solidified in a squaremold;a,pure metals;b,solid-solution alloys;c,structured obtained by usingnucleating agents（孕育剂）.Chill zone:极冷区，白口区，grain size due to very high cooling rate.Columnar zone:柱状区，large grain size due to lower cooling rate and heterogen
12、eousnucleation.Equiaxed zone:等轴晶区，homogeneous nucleation.Fig.10.2.Development of a preferred texture（择优质构）at a cool mold wall.Notethat only favorably oriented grains grow away from the surface of the mold.We can see,different metals have different solidified structures,and the nucleationagents affec
13、t it.OndnieiFig.10.3.Schematic illustration ofalloy solidification and temperaturedistribution in the solidifyingmetal.Note the formation ofdendrites in the mushy zone（多空隙的区域）.10.2.2 alloysRelnw TlThe solidification process of alloys can be schematically illustrated from Fig.10.3.From this figure,we
14、 can see,the solidification takes place in a temperature range,T1and Ts.The solidification process of this type alloy can be illustrated as follow:Chill zone formation-Between T1 and Ts个-Solidification begin-Dendrite formation CompleteFor this type dendrite,it can be named as columnar dendrite,with
15、three-dimensionalarms and branches.Below TsThe structure of dendrite influences the properties of casting seriously,so it isessential to find and study the effectors on its structure.As mentioned above,the structure of dendrite is affected by the mushy zone;in otherword,it can be described as differ
16、ent mushy zone during solidification,and the mushyzone can be named as freezing range,as this:na)当曲8 n(b)0.05-0.10%cSteelSand Chillmold mold口口5 20.55060%CSteelMinutes after pouring0.25-0.30%CSteelChillmold2Sand Chillmold mold16 2Minutes after pouringFig.10.4(a)Solidification patterns for gray cast iron in a 180mm square casting.Note that after 11 min.of cooling,dendrites reach each other,but the casting is stillmushy throughout.(b)Solidification of carbon steel in sand and chill(metal)molds.Note
