(完整版)机械类专业英语课文参考翻译
第一课
Text:
It is known that metals are very important in our life. Metals have the greatest importance for industry. All machines and other engineering[7endVi5niEriN] constructions have metal[5metl] parts; some of them consist only of metal parts.
众所周知，金属在我们的生活中是非常重要的，金属对于工业而言是有巨大的重要性，所有机器和其他工程构造都有金属零部件，其中一些还只能由金属组成。
There are two large groups of metals:
1) Simple metal- more or less pure chemical elements[5elimEnt]
2) Alloys[5AlCi]- materials consisting of a simple metal combined with some other elements.
有两大类金属：（1）纯金属——或多或少的金属元素（2）合金——组成纯金属的原料结合其他元素。
About two thirds of all elements found in the earth are metals, but not all metals may be used in industry. Those metals which are used in industry are called engineering metals. The most important engineering metal
is iron[5aiEn], which in the form of alloys with carbon[5kB:bEn] and other elements, finds greater use than any other metal. Metals consisting of iron combined with some other elements are known as ferrous[5ferEs] metals; all the other metals are called nonferrous[5nCn5ferEs] metals. The most important nonferrous metal are
copper[5kCpE], aluminum[E5lju:minEm], lead[li:d], zinc[ziNk], tin[tin], but all these metals are used much
less than ferrous metals, because the ferrous metals are much cheaper.
在地球上发现的所有元素中，大约三分之二是金属元素，但是并不是所有的金属都能够用于工业上。那些金属—我们用于工业上的金属—被称为工程金属，最重要的工程金属那就是铁，铁跟碳和其他元素结合形成合金的那些金属比其他金属发现有更大用途。铁与别的其他某些元素相结合而组成的金属称为黑色金属，此外所有其他金属都称为有色金属，最重要的有色金属是---铜，铝、铅、锌、锡。但是使
用这些有色金属比使用黑色金属要少的多，因为黑色金属便宜得多。
Engineering metals are used in industry in the form of alloys because the properties[5prCpEti] of alloys
are much better than the properties of pure[pjuE] metals. Only aluminum may be largely used in the form of simple metal. Metals have such a great importance because of their useful properties or their strength, hardness, and their plasticity[plAs5tisiti].
因为合金的特性比纯金属的好，所以工程金属以合金的形式用于工业，只有铝以纯金属的形式被广泛应用。金属因为具有强度、硬度和可塑性而发挥着特别重要的作用。
Different metals are produced in different ways, but almost all the metal are found in the forms of metal
ore[C:(r)] (iron ore, copper ore, etc[et cetra].)
以不同的方法生产不同的合金但是几乎所有的金属都是以金属矿的形式（铁矿、铜矿）被发现的。
The ore is a mineral[5minErEl] consistence of a metal combined with some impurities[im5pjuEriti]. In order to produce a metal from some metal ore, we must separate these impurities from the metal that is done
by metallurgy[me5tAlEdVi].
矿石是一种由金属与某些杂质相混合而组成的矿物质，为了用金属矿石来生产出一种金属，我们必须把杂质从金属矿中分离出去，那就要靠冶炼来实现。
2. Plastics and Other Materials
Text:
Plastics[5plAstik, plB:stik] have specific properties which may make them preferable[5prefErEbl] to traditional materials[mE5tIErIEl] for certain uses. In comparison[kEm5pArisn] with metals, for example, plastics have both advantages and disadvantages. Metals tend to be corroded[kE5rEud] by
inorganic[7inC:5^Anik] acids[5AsId], such as sulphuric[sQl5fjuErik] acid and hydrochloric[7haidrEu5klC:rik] acid. Plastics tend to be resistant to these acids, but can have dissolved or deformed by solvent[5sClvEnt], such as carbon tetrachloride[7tetrE5klC:raid], which have the same carbon base as the plastics. Color must be applied to the surface of metals, whereas it can be mixed in with plastics. Metals are more rigid[5ridVid] than most plastics while plastics are very light, with a specific[spi5sifik] gravity normally between 0.9 and 1.8.
Most plastics do not readily[5redili] conduct[5kCndQkt] heat or electricity[Ilek5trIsItI]. Plastics soften slowly and can easily be shaped[Feip] when they are soft.
塑料具有特殊的性能。对于某种用途而言，这些性能使得塑料比传统材料更为可取。例如，跟金属相比较，塑料既有优点也有缺点。金属易受到无机酸的腐蚀，如硫酸和盐酸，塑料能抵抗这些酸的腐蚀，但可被溶剂所洛解或引起变形，例如溶剂四氯化碳与塑料具有同样的碳基。颜色必定只能涂到金属的表面。而它可以跟塑料混合为一体。金属比大多数塑料刚性要好，而塑料则非常之轻，通常塑料密度在
0. 9-1. 8 之间。大多数塑料不易传热导电。塑料能缓慢软化，而当其还是在软的状态时，能容易成形。
It is their plasticity[plAs5tisiti] at certain temperatures[5temprItFE(r)] which gives plastics their main advantages over many other materials. It permits the large-scale production of molded[mEuld] articles, such
as containers, at an economic unit cost, where other materials require laborious[lE5bC:riEs] and often costly processes involving cutting, shaping, machining, assembly[E5sembli] and decoration.
在某一温度下塑料是处于塑性状态的，这就使塑料具备超过许多其他材料的主要优点。它容许大量生产单位成本低廉的模制式器件，例如，各种容器。于此，若用其他材料则需要大量劳力和往往需要很费钱的加工工艺，比如，切割、成形、加工、装配和装饰。
Plastics not only replace other materials. Their properties can be exploited[iks5plCit] for entirely[In5taIElI] new applications. For example, plastics heart valves[vAlv] and other human 'spare parts' have make possible many recent developments in surgery[5sE:dVEri].
塑料不仅可以代替其他材料，而且它的特性能被开拓应用于全新领域，比如：随着最近外科手术的发展可能做成塑料的心脏瓣膜和其他人类的器官。
There is no single plastics material which is suitable for all applications. It is important that the most suitable plastics should be chosen, and if necessary adapted[E5dApt], for each particular requirement. It is also important that the properties of the plastics chosen should be exploited to the best advantage.
没有一种纯塑料材料适用于各个领域，如果有必要改进，对于每个有特殊要求的来说选择最合适的塑料是最重要的，被选择的塑料材料的特性被开拓得到更好的应用也是很重要的。
A plastics article may need to differ in design and appearance from a similar article made from another material such as metal or wood. This is due[] not only to the properties of plastics but also to the techniques[tek5ni:k] employed in fabricating[5fAbrikeit] plastics. These techniques include
injection[in5dVekFEn] molding[5mEuldiN], blow molding, compression molding, extrusion[eks5tru:VEn] and vacuum[5vAkjuEm] forming.
塑料器件可能需要用其他材料比如：与金属或木材制作的类似的器件从设计和外观上加以区别，这不仅是由于塑料性能不同的原因，也是由于制造塑料产品所用的技术不同所致，这些技术包括：注塑、模制、吹塑模制、压模、挤压和真空成型等。
3. Casting and Die-Casting Alloys
Text:
Casting[5kB:stiN] is one of the oldest metal working techniques known to man. Our country made metal castings as early as 2000 B.C., and the process used then is not much different in principle[5prinsEpl] from the one used today.
铸造是入类所掌握的最古老的金属加工技术之一。我国早在公元前2000 年就已把金属制成铸件，而所使用的工艺从原理上和今天的工艺没有多大的区别。
Foundry[5faundri] processes consist of making molds, preparing and melting[melt] the metal,
pouring[pC:, pCE] the metal into the molds, and cleaning the castings. The product of the foundry is a casting, which may vary from a fraction[5frAkFEn] of a kilogram to several hundred tons. It may also vary in composition[kCmpE5ziFEn] as practically all metals and alloys can be cast.
铸造工艺由制模、备料和金属熔炼，金属液浇注入模和铸件清砂等。铸造的产品是铸件，铸件可能从零点几公斤到几百吨范围变化。实际上所有金属在成分上也是变化的，而合金也可以铸造。
The metals most frequently cast are iron, steel, aluminum and so on. Of these, iron, because of its low melting point, low price and ease of control, is outstanding for its suitability[9sjU:tE`bIlEtI] for casting and is used far more than all the others.
最常铸造的金属是铸铁、钢、铝等等。这些金属中，铸铁，由于其低熔点，低价格和易控制，因而其铸造适应性是最突出的，而且使用也远比所有其他金属多。
Casting is a widely used method of producing metal products, particularly those which are
intricate[5intrikit]. Since molten materials will readily take the shape of the container into which they are poured, it is nearly as easy to cast fairly complex shapes as to produce simple forms.
由于熔融的物料能容易取得被浇注进去的容器（模型）的形状，因此，几乎像生产简单形状铸件那样颇为容易地铸造出复杂形状的铸件。
The place where the metals are cast is called a foundry. The most important of cast metals is cast iron which is made from pig iron by remelting it in a special melting furnace[5fE:nis] called a cupola[5kju:pElE].
铸造金属的地方叫做铸造车间。最重要的铸造金属是铸铁，铸铁是用生铁在一个特殊的熔炉—叫冲天炉的炉子中重新熔炼而制造出来的。
From the cupola, the cast iron flows into ladles[5leidl] of different size, and from these ladles it is poured into the molds.
从冲天炉中出来的铁水流入到不同规格的铁水包中，并从这些铁水包中被浇注到模型中。
The molds may be of two kinds: sand molds and metal molds. A metal mold consists of two hollow parts which should be joined for pouring the metal into it. The inside of this mold is covered with carbon or graphite[5^rAfait] so that the metal could not stick[stik] to the wall of the form. When the metal has
solidified[sE5lidifai], these hollow parts are disjoined and the casting is taken out. There are also special molds in which large blocks of steel can be cast. These molds are usually made of cast iron and are called
ingot[5iN^Et] molds, which the blocks of steel produced by pouring the metal into these molds are called ingots and the process is called ingot casting.
模型有两种类型:砂模和金属模。金属模是由两个中空的部件组成，它们应被联结在一起以便将金属液浇入模箱中。这模腔的内侧是要涂以碳粉或石墨，因此金属不玫于粘贴到型腔壁上口当金属液凝固后，这中空的型箱部件被打开并取出铸件。也有一种特殊模型，在该模型中可以铸造大型钢块。这些模型通常用铸铁米制造，并被称为锭模。而浇注金属液到这些模子中生产出的钢块被称为钢锭。该工艺过程叫锭铸。
A relatively[5relEtIvlI] wide range of nonferrous alloys can be die-cast. The principal base metals used, in order to commercial importance, are zinc, aluminum, copper, magnesium[mA^5ni:zjEm], lead, and tin. The alloys may be further classified as low-temperature alloys and high-temperature alloys; those having a casting
temperature below 538C, such as zinc, tin, and lead, are in the low-temperature class. The low-temperature alloys have the advantages of lower cost of production and lower die-maintenance[5meintinEns] costs. As the casting temperature increases, alloy and other special steels in the best treated condition are required to resist the erosion[i5rEuVEn] and heat checking[5tFekiN] of die surface. The destructive[dis5trQktiv] effect of high temperatures on the dies has been the principal factor in retarding[ri5tB:d] the development of
high-temperature die castings.
相当大量的有色金属合金可以进行模铸}h 用的主要而基本的金属，按其在工业上应用的重要性的顺序是锌、铝、铜、锰、铅和锡。这些合金可以进一步进行分类为低温类合金和高温类合金。铸造温度低于538℃的那些合金，就像锌、锡和铅,是属于低温类合金。低温类合金具有低生产成本和低的模具维修费用等优点。当铸造温度上升时，需要最佳条件下处理过的合金钢和其他特种钢来抵抗腐蚀及防止模具表面的热裂纹。高温在模具上的损坏作用已经成为阻碍、延缓高温模铸发展的主要因素。
Another factor governing[5^QvEniN] the choice of alloy is the erosive[i5rEusiv] or solvent[5sClvEnt] action of the molten metal on the respective[ris5pektiv] machine parts and dies. This action increases with temperature, although it is more pronounced[pr5naunst] with some alloys than with others. Aluminum, in particular, has a destructive action on ferrous metals and, for this reason, is seldom melted in the machine, whereas the copper-base alloys are never melted in the machine.
控制选择合金的另外一个因素就是熔融的金属在相关的机器零件上和模具上的腐蚀或溶解作用。
这种作用随着温度的升高而增加，甚至某些合金比另一些合金更为明显。特别是.铝对黑色金属有一种破坏作用，为此、铝几乎不熔混于机器零件中，而铜基合金是决不能熔混于机器构件中的。
4. Forging
Text:
Press forging[5fC:dViN] employs a slow squeezing[skwi:z] action in deforming[di:5fC:m] the plastic metal, as contrasted with the rapid-impact[5impAkt] blows of a hammer. The squeezing action is carried completely to the center of the part being pressed, thoroughly working the entire section[5sekFEn]. These presses are the vertical[5vE:tikEl] type and may be either mechanically[mi5kAnikEli] or
hydraulically[hai5drC:lik] operated. The mechanical presses, which are faster operating and most commonly used, range in capacity[kE5pAsiti] from 500 to 1000 tons.
与锤锻的快速冲击不同，压力机锻造是用缓慢的挤压作用使塑性金属变形。这挤压作用完全被施加
到正在被压锻的零件中心位置上，直至彻底使整个工件得到加工。这些压力机都是立式的，可能是机械
操作也可能是液压操作的。机械操作压力机，操作速度比较快，使用最普遍，锻造能力从500 吨到10000 吨范围。
For small press forgings, closed impression dies are used and only one stoke of the ram[rAm] is normally required to perform[pE5fC:m] the forging operation. The maximum[5mAksimEm] pressure is built up at the
end of the stroke which forces the metal into shape. Dies may be mounted[maunt] as separate units, or all the cavities may be put into single block. For small forgings, individual[7indi5vidjuEl] die unites are more convenient. There is some difference in the design of dies for different metals; copper-alloy forgings can be
made with less draft[drB:ft] than steel, consequently more complicated[5kCmplikeitid] shapes can be produced. These alloys flow well in the die and are rapidly extruded
对于小型压力锻使用闭式锻模。通常要求锻锤仅一个冲程就完成锻造工艺。在冲程终端产生最大压力，该冲击压力迫使金属成形。模具可由各白独立的单元装配而成，即把所有个别模腔都放到一起，组
成整体。对于小型锻件使用分模装置更为方便。对于不同的金属在模具设计上有些区别.铜合金锻件比
钢件用较小的拔模斜度，因此可生产更加复杂形状的锻件。这些合金在该种模具中流动性好，而且能快
速挤压成形。
In the forging press, a greater proportion of the total work put into the machine is transmitted[trAnz5mit]
to the metal than in a drop hammer press. Much of the impact of the drop hammer is absorbed by the machine
and foundation. Press reduction of the metal is faster, and the cost of operation is consequently lower. Most
press forgings are symmetrical[si5metrikEl] in shape, having surfaces which are quite smooth, and provide a closer tolerance[5tClErEns] than is obtained by a drop hammer. However, many parts of irregular[i5re^julE]
and complicated shapes can be forged more economically by drop forging. Forging press is often used for
sizing operations on parts made by other forging processes.
锻压机比落锤锻，输入到机器里的总能量中有更大部分的能量被传输到金属坯料上。落锤锻的冲击
能量被机器和基础吸收得较多(比起压力机来〕。金属上的压力衰减较快，因此生产成本比较低。大多数
压力锻锻件形状、产生的表面都是对称的，而且表面非常光滑，并比落锤锻件的公差尺寸更加精确。然
而落锤锻造可以锻制形状复杂而不规则的锻件，因而较为经济。锻压机常常用来为其他锻造工艺所生产
的锻件进行整形和校正加工用。
In drop forging, a piece of metal, roughly[5rQflI] or approximately of the desired[di5zaiE] shape, is placed between die faces having the exact form of the finished piece, and forced to take thin form by drawing the dies together. Large ingots are now almost always forged with hydraulic presses instead of with steam hammers,
since the work done by a press goes deeper. Further, the press can take a cooler ingot and can work to closer dimensions[di5menFEn]. The forging should be done at about the same temperature as rolling[5rEuliN]; the process improves the physical properties of the steel just as rolling does. In the final forging it is important not
to have the steel too hot, for overheated steel will have poor mechanical properties when cooled. In heating for forging, temperature is usually judges by the eye, but where large numbers of the same pattern are made, the
piece to be forged are heated in furnaces[5fE:nis] in which the temperature is indicated[5indikeit] by
pyrometers[7paiE5rCmitE], and often is automatically controlled.
在落锤锻中，一块金属坯料，粗糙的即大体像所要求零件形状那样，被放入到具有成品件那样精确形状的模面之间，然后施加压力使模具紧紧结合在一起以锻取模腔形状。这一方法广泛用来制造钢件和黄钢件。大型金属锭现在几乎都是用液压压力机来锻造的，而不用蒸汽锤。因为用压力机锻造，变形更加深透。将来压力机可对付冷金属锭并能加工得到更加精确的尺寸。锻造将在大约与辊轧同样的温度下进行，这种工艺正像轧制那样可改善金属的物理性能。最后火锻时，不使钢太热很重要，因为过热钢冷却后，其机械性能较差。为锻件加热，温度通常是以肉眼来判断的，但在生产大量相同锻件的场合，要锻造的坯件是在有高温计指示温度的炉子中来加热，并且常常是自动控制的。
5. Soldering and Welding
Text:
There are a number of methods of joining metal articles[5B:tikl] together, depending on the type of metal and the strength of the joint which is required.
把金属件连接在一起的方法有若干个，用哪一种方法，要根据金属种类和所要求的焊缝强度来决定。
Soldering[5sCldEriN] is the process of joining two metals by a third metal to be applied in the molten state. Solder[5sCldE, 5sC(:)-] consists of tin and lead, while bismuth[5bizmEW] and cadmium[5kAdmiEm] are often included to lower the melting point. One of the most important operations in soldering is that of cleaning the surface to be joint, this may be done by some acid cleaner.
软焊是要用溶融状态的第三种金属来使两件金属连接在一起的工艺。焊料由锡和铅组成。而常常含有铋和镉。目的是要降低熔点。软钎焊中最重要的工序之一就是清理焊缝表面。这可以用某种酸性清除剂来进行。
Soldering gives a satisfactory joint for light articles of steel, copper or brass[brB:s], but the strength of a soldered joint is rather less than a joint which is brazed[breiz], riveted[5rivit] or welded[weld]. These methods
of joining metal are normally adopted[E5dCptid] for strong permanent[5pE:mEnEnt] joints.
软钎焊能为轻型钢件、铜件和黄铜件生产满意的焊缝，但软钎焊的焊缝强度比起硬钎焊、铆接和焊接来要弱些。连接金属的这些方法，通常用来产生强固的永久性的焊缝。
The simplest method of welding two pieces of metal together is known as pressure welding. The ends of metal are heated to a white heat-for iron, the welding temperature should about 1300C-in a flame[fleim]. At
this temperature the metal becomes plastic. The ends are then pressed or hammered together, and the joint is smoothed off. Care must be taken to ensure that the surfaces are thoroughly[5WQrElI] clean first, for dirt will weaken the weld. Moreover, the heating of iron or steel to a high temperature causes oxidation[Cksi5deiFEn], and a film[film] of oxide[5Cksaid] is formed on the heated surfaces. For this reason, a flux[flQks] is applied to the heated metal. At welding heat, the flux melts, and the oxide particles are dissolved in it together with any other impurities which may be present. The metal surfaces are pressed together, and the flux is squeezed out
from the center of the weld. A number of different types of weld may be used, but for fairly thick bars of metal,
a v-shaped weld should normally be employed[im5plCi]. It is rather stronger than the ordinary but weld.
把两件金属焊在一起的最简单的方法称做压力焊。用火焰把金属两端加热到白炽状态—铁的焊接温度为1300C 左右—在这一温度下，金属变成塑性，然后对两端施压或锤击使之结合在一起。最后再将
焊缝清理千净。必须注意首先保证表面完全清洁，因脏物将会使焊缝强度削弱。此外，加热铸铁或钢到高温会引起氧化井在焊接表面形成氧化皮。因此用助焊剂施于加热的金属上。达到焊接温度时刻，助焊剂熔化，将氧化物粒子跟任何其他可能存在的杂质一起都熔解于助焊剂中，金属表面被压合在一起，而助焊剂就从焊缝中间被挤出。可能使用若干不同类型的焊缝，但对于颇为粗厚的金属件，通常使用V
型焊缝。该焊缝比起普通的对接焊缝来要强固些。
The heat for fusion[5fju:VEn] welding is generated in several ways, depending on the sort of metal which
is being welded and on its shape. An extremely hot flame can be produced from an
oxy-acetylene[CksiE5setili:n] torch[tC:tF]. For certain welds an electric arc is used. In this method, an electric current is passed across two electrodes[I5lektrEJd], and the metal surfaces are placed between them. The electrodes are sometimes made of carbon, but more frequently they are metallic[mi 5tAlik]. The work itself constitutes one of them and the other is an insulated[5insjuleitid] filler[5filE] rod[rCd]. An arc struck[strQk] between the two, and the heat which is generated melts the metal at the weld. A different method is usually employed for welding sheets or plates of metal together. This is known as spot welding. Two sheets or plates
are placed together with a slight[slait] overlap[5EuvE5lAp], and a current is passed between the electrodes. At welding temperature, a strong pressure is applied to the metal sheets. The oxide film, and any impurities which are trapped[trApt] between the sheets, are squeezed out, and the weld is made.
可用几种方法来产生溶焊的热，用何种方法，要根据将要焊接的金属种类和根据其形状来决定。由氧乙炔焰可产生强烈的火焰。对于某种焊缝，可用电弧来焊接。在这一系列重要的焊接过程中，电弧可为熔化金属供热，而焊剂起着保护和清理焊缝的作用，而且常常也是起着熔炼控制作用。最广泛使用的助焊剂保护电弧焊的形式是一种称作金属弧焊的手工操作工艺。在这一方法中，电流经两个电极流过，而金属表面则被置于两电极之间。电极(电焊条)有时用碳棒制作，但更常用金属来制作。工件本身构成它们中的一极而另一极是一具有绝缘填充剂的焊条。两极之间电弧放电，由此产生的热去熔化在焊缝处的金属。通常使用不同的方法去把金属薄板或厚板焊接在一起。这就叫做点焊。两块薄板或厚板以边沿稍稍搭叠的方式放在一起，一电流从两极之间通过.达到焊接温度时刻，对金属板施加强压，氧化皮和陷入薄板中间任何杂质都会被挤出，而完成了焊缝连接.
6. Heat Treatment and Hot Working of Metals Text:
We can alter[5C:ltE] the characteristics[7kAriktE5ristik] of steel in various ways. In the first place, steel which contains very little carbon will be milder than steel which contains a higher percentage of carbon, up to the limit of about 1.5%. Secondly, we can heat the steel above a certain critical[5kritikEl] temperature, and then allow it to cool at different rates. At this critical temperature, changes begin to take place in the
molecular[mEu5lekjulE] structure of the metal. In the process known as annealing[A5ni:liN], we heat the steel above the critical temperature and permit it to cool very slowly. This causes the metal to become softer than before, and much easier to machine. Annealing has a second advantage; it helps to relieve[ri5li:v] any internal stresses which exist in the metal. These stresses are liable[5laiEbl] to occur through hammering or working the metal, or thorough[5WQrE] rapid cooling. Metal which we cause to cool rapidly contracts[5kCntrAkt] more rapidly on the outside than on the inside. This produces unequal contractions, which may give rise to distortion[dis5tC:FEn] or cracking[5krAkiN]. Metal which cools slowly is less liable to have these internal stresses than metal which cools quickly.
我们可以用各种方法改变钢的特性。首先，对于上限率为 1.5%的钢，含碳量低的钢比含碳量高的钢软。其次，我们可以将钢铁加热到某个特定的临界温度以上，然后让它以不同的速度冷却，在这个临界温度，分子结构开始分解，在退火的工艺过程中，我们将钢加热到临界温度以上然后缓冷，在这个过程中，比以前软，并且易于机械加工，退火还有另一个优点，它帮助减轻金属内部存在的内应力，这些应力可能通过锤击或加工金属时或者通过快速冷却时产生的，我们将金属快速冷却时，金属的外部比内部收缩的快，使得金属收缩不均匀，可能导致其变形或产生裂纹，金属缓慢冷却比金属快速冷却所产生的内应力少。
On the other hand, we can make steel harder by rapid cooling. We heat it up beyond the critical temperature, and then quench[kwentF] it in water or some other liquid. The rapid temperature drop fixes the structure change in the steel which occurred at the critical temperature, and makes it very hard. But a bar of this hardened steel is more liable to fracture[5frAktFE] than normal steel. We therefore[5TZEfC:] heat it again to a temperature below the critical temperature, and cool it slowly. This treatment is called
tempering[5tempEriN]. It helps to relieve the internal stresses, and makes the steel less brittle[5britl] than before. The properties of tempered steel enable us to use it in the manufacture of tools which need fairly hard steel. High carbon steel is harder than tempered steel, but it is more difficult to work.
另一方面，我们可以通过快速冷却使金属淬硬，我们将它加热到远远超过临界温度以上，然后把它放入到水里或其他的液体里，温度下降很快，在它的形状不改变的情况下，降到临界温度，使它淬硬，但是，由硬钢制成的样件比普通钢件容易断裂，因此，我们将它再次加热到临界温度以下的某一温度，然后缓冷，这个方法叫回火，它帮助减少内应力，并且使钢的脆性减少，回火钢的特性使得我们可以用它来制造那些需要用相当硬的钢制造的格局。高碳钢比回火钢更硬，可是加工则困难得多。
These heat treatments take place during the various shaping operations. We can obtain bars and sheets of steel by rolling the metal through huge rolls in a rolling mill[mil]. The roll pressures must be much greater for
cold rolling than for hot rolling, but cold rolling enables the operators to produce rolls of great
accuracy[5AkjurEsi] and uniformity[7ju:ni5fC:miti], and with a better surface finish. Other shaping operations include drawing into wire, casting in moulds, and forging.
这些热处理都是在各种成型加工过程中进行的。钢在轧钢厂经过巨大轧机的轧制，能成为各种型钢
和钢板。冷轧的轧制压力必须比热轧的大得多，但是冷轧使操作者能够轧出精确度和均匀性很高、表面
光洁度较好的钢材。其它成型加工过程还有拉丝、模煅和铸造。
The mechanical working of metal is the shaping of metal in either a cold or hot state by some mechanical means. This does not include the shaping of metals by machine or grinding, in which processes metal is
actually machined off, not does it include the casting of molten metal into some form by use of molds. In mechanical working processes, the metal is shaped by pressure-actually forging, bending[5bendiN], squeezing, drawing, or shearing[5FiEriN] it to its final shape. In these processes the metal may be either cold-or hot- worked. Although normal room temperatures are ordinarily used for cold working of steel, temperatures up to
the recrystallization[ri:`krIstElaIz] range are sometimes used. Hot working of metals takes place above the recrystallization or work-hardening range. For steel, recrystallization starts around 650 to 700C, although most hot work on steel is done at temperature considerably[kEn5sIdErEbElI] above this range. There is no
tendency[5tendEnsi] for hardening by mechanical work until the lower limit of the recrystalline range is reached. Some metals, such as lead and tin, have a low recrystalline range and can be hot-worked at room temperature, but most commercial metal require some heating. Alloy composition[kCmpE5ziFEn] has a great influence[5influEns] upon the proper[5prCpE] working range, the usual result being to raise the recrystalline range temperature. This range may also be increased by prior cold working.
金属的机械加工是借助某些机械工具对冷的或热状态的金属进行成型加工，既不包括在加工过程中
金属被切离的切削加工或磨削加工，也不包括模注，在成型加工过程中，金属通过压力成型，这些压力
包括压力锻，弯曲，挤压，拉拔或冲压成型，在这些压力中，金属可以冷却加工也可以热加工，虽然钢
件的冷加工一般都在室温下进行，但有时也在再结晶温度下进行，对于钢件，再结晶温度发生在650~700 C 之间，虽然大部分钢件的热加工发生在这个温度以上，除非达到最低的再结晶温度以下，否则不存在
单纯通过机械加工而达到加强硬度的可能，某些金属，像铅或锡，在结晶温度低，可在室温进行加工，
但其他工业金属需加热，合金的成分对于它的加工方法变化很大，这些加工方法通过它的再结晶温度而
变化，这些改变在基本的加工以前改变.
7. Kinds of Steels, Mechanical Properties of Metals Text:
There are two general[5dVenErEl] kinds of steel: carbon steel and alloy steel. Carbon steel contains only iron and carbon, while alloy steel contains some other alloying elements such as nickel[5nikl],
chromium[5krEumjEm], manganese[7mAN^E5ni:z, 5mAN^Eni:z], molybdenum[mE5libdinEm], tungsten[5tQNstEn], vanadium[vE5neidiEm, -djEm], etc.
有两类钢铁，碳钢和合金钢，碳钢仅仅含铁和碳元素，而合金钢还包括其他的一些合金元素，例如: 镍、铬、锰、铝、钨和钒等等。
1. Carbon steels
(1) Low carbon steel containing from 0.05 to 0.15 percent carbon; this steel is also known as machine steel.
(2) Medium carbon steel containing from 0.15 to 0.60 percent carbon.
(3) High carbon steel containing from 0.6 to 1.50 percent carbon: this steel is sometimes called "tool steel".
1.碳钢
（1）低碳钢含碳量从0.05％到0.15％之间变化，这类钢也称作机械钢。
（2）中碳钢含碳量从0.15％0.60％之间变化
（3）高碳钢的含碳量从0.60％到 1.5％之间变化，这类钢有时被叫做工具钢
2. Alloy steels
2.合金钢
(1) Special alloy steel, such as nickel steel, chromium steel.
（1）特殊合金钢像镍钢、铬钢
(2) High-speed steel also known as self-hardening steel.
（2）高硬也叫做自硬钢的高速钢
Carbon steels are the most common steels used in industry. The properties of these steels depend on the percentage of carbon they contain. Low-carbon steels are very soft and can be used for bolts[bEult] and for machine parts that do not need strength.
碳钢是在工业中应用最普遍的钢类，这些钢的性能仅仅由他们的含碳量决定。低碳钢非常柔软并且能被用来制造不需要多大强度的螺钉和机械零件。
Medium carbon steel is a better grade and stronger than low carbon steel. It is also more difficult to cut
than low carbon steel.
中碳钢是比低碳钢较高级的钢，强度较大，并且加工比较困难。
High carbon steel may be hardened by heating it to a certain temperature and then quickly cooling in water. The more carbon the steel contains and the quicker the cooling is, the harder it becomes. Because of its high strength and hardness, this grade of steel may be used for tools and working parts of machines.
高碳钢经过加热到一定温度然后再在水中快冷可以被淬硬，钢含碳量越高，冷却越快，钢就变得越硬。由于它的高强度和高硬度，这类钢可以被用作制造工具和机械中的运作部件。
But for some special uses, for example, for gears[^iE], bearings[5bZEriN], springs[spriN], shafts[FB:ft]
and wire[5waiE], carbon steels cannot be always used because they have no-properties needed for these parts.
但是对于一些特殊的用途，例如齿轮、轴承、弹簧、轴和电线，碳钢由于没有这些零件所需的性能，因此不是总能被用。
Mechanical properties are the characteristic responses[ris5pCns] of a material to applied forces. The knowledge of mechanical properties of materials is very essential[i5senFEl] in order to construct a mechanically sound[saund] structure such as a bridge on the river. Mechanical properties can be
determined[di5tE:min] by conducting experimental tests on the material specimen[5spesimin, -mEn]. Some important mechanical properties of materials are:
力学性能是材料对所施外加压力的反应特性，力学性能知识的引入本质是构造一个机械结构，就好像是河上的桥一样起到连接作用，通过在试样上做实验机械性能可以被了解。材料的一些重要的机械性能如下：
(1) Strength (in tension[5tenFEn], compression, shear and bending)
(2) Stiffness[5stifnis]
(3) Ductility[dQk5tiliti]
(4) Impact strength
(5) Hardness
(6) Toughness[5tQfnis]
（1）强度（2）刚度（3）延展性（4）冲击强度（5）硬度（6）韧度
1.Strength or mechanical strength of a material may be defined as the ability of the material to sustain
loads without undue[5Qn5dju:] distortion[dis5tC:FEn] or failure. Material should have adequate[5Adikwit] strength when subjected[5sQbdVikt] to tension, compression, shear, bending or torsion[5tC:FEn] as per the intended use.
在不过分就去和失效的情况下，材料的机械强度由它支撑的能力阐明，当材料按照预定的用途而承受拉力、压力、剪力、弯曲应力或扭力时应该具有足够的强度。
For example the crankshaft[5krANkFB:ft] of an automobile[5C:tEmEubi:l, 7C:tE5mEubil, 7C:tEmE5bi:l] should have proper torsion strength.
例如：汽车的传动轴应该有一定的抗扭强度。
2. Stiffness. Stiffness is the ability of a material or shape to resist elastic[I5lAstIk] deflection[di5flekFEn]. For identical[ai5dentikEl] shapes, the stiffness is proportional[prE5pC:FEnl] to the modulus[5mCdjulEs] of elasticity[IlAs5tIsItI]. A material which deforms less under a given load is more stiff than on which deforms more.
刚性，刚性是塑性变形的能力，对于有固定形状的条件来说，刚性是弹性变形的模数在给定在和条件下变形最小的材料比变形较大的材料刚度大。
8. Gears and Reducers
Text:
Gears[^iE] are vital[5vaitl] factors in machinery[mE5Fi:nEri]. One of the first mechanism[5mekEnizEm] invented using gears was the clocks. In fact, a clock is little more than a train of gears.
Considerable[kEn5sidErEbl] study and research have been made on gears in recent years because of their wide use under exacting[i^5zAktiN] conditions. They have to transmit[trAnz5mit] heavier loads and run at higher speeds than ever before. The engineers and the machinists[mE5Fi:nist] all consider gearing the prime element
in nearly all classes of machinery.
齿轮在机械中占有极其重要的作用。第一个利用齿轮做成的机械装置就是钟表，事实上，它只不过是用了一系列的齿轮。对于它可以在严格的条件下的广泛使用，在齿轮上做了大量的学习和研究。相比过去，它们现在必须在更高的速度下传递更重的负荷。工程师和机器操纵工人都认为齿轮在几乎所有的机器的零件中占有首要的因素。
1. Spur[spE:] gears
Spur gears are used to transmit power and rotary[5rEutEri] motion between parallel[5pArElel] shafts. The teeth are cut parallel to the axis of the shaft on which the gears are mounted. The smaller of two gears in
mesh[meF] is called the pinion[5pinjEn], and the larger is customarily[`kQstEmErElI;9kQstE`merElI] designated[5dezi^neit] as the gear. In most applications, the pinion is the driving element whereas the gear is
the driven element.
1.直齿圆柱齿轮
直齿圆柱齿轮用于平行轴之间传递力和回转运动，轮齿被切制成与安装齿轮的轴之轴线相平行。两啮合齿轮中较小的叫小齿轮，大的习惯上叫齿轮，在大多数情况下，小齿轮是主动轮，大齿轮叫从动轮。
2. Helical [5helikEl] gears
Helical gears have certain advantages, for example, when connecting parallel shafts they have a higher
load-carrying capacity than spur gear with the same tooth numbers and cut with the same cutter.
2．斜齿圆柱齿轮
斜齿圆柱齿轮具有特定的优点，比如，当连接平行轴的用相同刀具切削出来的并齿数相同的斜齿轮比直齿轮具有较高的承载能力。斜齿轮也能用于连接相互成任意角度的非平行轴。
Helical gears can also be used to connect nonparallel [5nCn5pArElel], non-intersecting [7intE5sekt] shafts at any angle to one another.
斜齿轮也能用于连接相互成任意角度的非平行轴。
The maximum [5mAksimEm] gear ratio obtainable with a single pair of gears varies [5vZEri] with the
type of gear and the application. The following are approximate maxima [5mAksimE] for the various type for average load conditions: spur, 8; parallel-shaft helical, 10; straight bevel [5bevEl], 6; spiral[5spaiErEl] bevel, 8; hypoid [5hai7pCid], 12; and worm [wE:m], 80. For lightly loaded, instrument[5instrumEnt], and positioning [pE5ziFEniN] gears, these rations can be exceeded[ik5si:d]. Rations as high as 400 or higher can be obtained with gears that resemble tapered [5teipE] worms meshing with hypoid gear. For heavily loaded gear, the given rations may be so high that a reasonable gear size precludes [pri5klu:d] a satisfactory pinion.
一对齿轮能获得的最大传动比随齿轮类型和应用的变化而变化，以下是各种类型的齿轮的平均载荷条件的近似最大化，直齿是8，平行轴斜齿轮是10，直齿锥齿是6，曲线齿锥齿轮8，准双曲面12，蜗轮蜗杆8，对于轻载荷和定位齿轮这些传动比被超出，类似于成锥形的蜗轮蜗杆，和准双曲面齿轮能够获得的传动比高达400 或更高，如此高以至于00 的齿轮尺寸不可能令人满意。
Since the ratio in a single pair of gears is the quotient [5kwEuFEnt] of the tooth number, and since there usually are limitations on both the minimum and maximum numbers of teeth on the available [E5veilEbl] gears, it follows that the number of ratios obtainable in a single pair is limited. To enlarge the coverage [5kQvEridV] it is necessary to use multiple[5mQltipl] pairs, or trains. The overall[5EuvErC:l] speed ratio in a train is the
product of the ratios in each pair. In certain cases an exact ratio cannot be obtained with gears, but by using two or more parts, the desired ratio can be approximated[E5prCksimeit] to any degree of precision.
一对齿轮的传动比齿数的商，它们通常是限制在有效齿轮的最大和最小齿数之间，因此，一对齿轮获得的传动比是受限制的，为了扩大范围，用多级齿轮副或系列是必要的，在一个系列中，总速比是每对齿轮产生的传动比。
As a convenience for machine builders and users, packaged[5pAkidV] speed reducers, following an industry-accepted pattern [5pAtEn], are manufactured[7mAnju5fAktFE] in a wide variety of types, configurations [kEn7fi^ju5reiFEn], speed ratios, and capacities; these consist of a box or housing containing bearings, shafts, lubricant [5lu:brikEnt], and shaft oil seals[si:l]. Speed increasers are usually custom build.
在某种情况下，一个确切的传动比不能由齿轮副获得，但是用两对或更多对时，要求的传动比能达到精确等级，为了对机器制造者和使用者方便起见，各种整装式减速器，根据工业通用的试样被大量的多样化的类型的组合的速度比的生产制造，这些由箱子组成或给含有轴承轴润滑剂和轴油封装外罩增速器通常被定别。
All speed reducers when operating continuously become hot because of friction [5frikFEn] in the teeth, in the lubricant, in the bearings, and in the oil seals. If the heat is generated at a faster rate than it can be dissipated [5dIsIpeItId] to the atmosphere, the lubricant may deteriorate[di5tiEriEreit] and the gear or bearing fail.
所有的减速器当被连续使用时，由于轮齿在润滑剂轴承和油封件的摩擦会变热，如果热量的产生在空气中散逸的速度还快的话，润滑剂不能损坏，并且轴承和齿轮失效。
9. Worm Gear Sets
Text:
Worm[wE:m] gear sets are widely used because of the many advantages obtained[Eb5tein] by their tooth action and load carrying capacity[kE5pAsiti]. A large speed reduction[ri5dQkFEn] or a high increase of
torque[tC:k] can be attained[E5tein] with the worm gear set. Compactness[kEm5pAktnis] of design is easy to obtain with such a combination[7kCmbi5neiFEn]. Worm gear drives are quiet and vibration[vai5breiFEn] free.
蜗轮装置由于啮合作用和传递载荷能力获得的许多优点而被广泛应用，大量转矩的减速或增速装置由蜗轮装置完成，设计的紧凑，用这样一个结合体是容易得到的，蜗轮是平稳且无振动的。
A worm gear set consists of the worm, which is very similar[5similE] to a screw[skru:], and the worm gear, which is a helical[5helikEl] gear. The shafts[FB:ft] upon which the worm and the gear are mounted are usually at right angels but not in the same plane[plein]. The usual practice is to have the worm drive the worm gear. With same ratios[5reiFiEu], it is possible to have a gear driver the worm. However, with large ratios, it is impossible for the gear to drive the worm.
一个蜗轮装置由蜗杆——非常类似于螺丝和蜗轮——一个斜齿轮组成的，安装蜗杆和蜗轮的轴通常相互垂直而不在同一平面中，通常习惯上使蜗杆驱动蜗轮。以小的传动比，使一个齿轮驱动蜗杆是有可能的，但是，大的传动比，使一个齿轮驱动蜗杆是不可能的。
The worm can be made with either right-hand or left-hand thread[Wred]. Also, like a screw, it can be
made with single, double, triple[5tripl], or quadruple[5kwCdrupl] thread. A single-thread worm advances the worm gear a distance equal[5i:kwEl] to pitch[pitF] for each complete worm rotation. The distance advanced is called the lead[li:d]. Thus, the pitch equals[5i:kwEl] the lead for a single thread. A double-threaded worm has a lead which is twice the pitch.
蜗杆可以被制成右螺纹或左螺纹，同样像螺丝一样，蜗杆可以被制成单、双螺纹，三重或四重螺纹，单螺纹的蜗杆推进蜗轮等节距前进来完成每个完整的蜗杆转动，间距的推进称为节距。因而节距等于单螺纹的螺距，双螺纹的蜗杆螺距是两倍的节距。
The geometry[dVi5Cmitri] of a worm is similar to that of a power screw. Rotation of the worm
simulates[5simjuleit] a linearly[5liniEli] advancing involute[5invElu:t] rack[rAk]. The geometry of worm gear (sometimes called a worm wheel[wi:l]) is similar to that of a helical gear, except that the teeth are curved to envelop[in5velEp] the worm. Sometimes the worm is modified to envelop the gear. This gives a greater area of contact, but requires extremely[iks5tri:mli] precise[pri5sais] mounting.
蜗杆的几何形状类似于机械螺纹，蜗杆的转动与一个渐开线导轨直线移动是相仿的。蜗轮几何形状（有时被称为蜗轮）类似于斜齿轮，除了包围在蜗轮上的齿是弯曲的以外。有时把蜗杆齿制成包裹在蜗轮，这就提供了更大的接触面积，但安装精度要求更高了。
10. Cams
Text:
A rotary[5rEutEri] cam[kAm] is part on a machine which mechanically[mi5kAnikEli] changes
cylindrical[sI5lIndrIk(E)l] motion to straight-line motion. The cam, which is mounted on a shaft, is usually driven by a motor[5mEutE] either applied[E5plai] directly to the cam shaft or connected by pulleys[5puli] or gears. The purpose[5pE:pEs] of a cam is to transmit various[5vZEriEs] kinds of motions to other parts of a machine.
一个转动的凸轮是机械的一部分，也就是用机械的方式使回转运动变为直线运动。凸轮被安装在轴上通常由直接用到凸轮轴或是由皮带轮或齿轮联结成的任一原动力驱动。凸轮的目的是传递各种各样的运动到机械的其他部分。
Practically every cam must be designed and manufactured to fit special requirements. Though each cam
appears to be quite different from the other, all the cams work in a similar[5similE] ways. In each case, as the cam is rotated or turned, another part in contact with the cam, called a follower[5fClEuE], is moved either left and right, up and down, or in and out. The follower is usually connected to other parts on the machine to accomplish[E5kCmpliF] the desired[di5zaiE] action. The direction the follower move depends upon the position of the framework[5freimwE:k] which attaches[E5tAtF] the cam and follower to the machine. If the follower loses contact with the cam, it will fail to work.
几乎每个凸轮必须被设计和制造以适合特殊的要求，虽然每个凸轮显现的十分不同于其他凸轮。但是所有的凸轮都以类似的方式工作。在任何情况下，与凸轮转动或旋转时，与凸轮接触的另一部分成为从动件，向左或向右，向上或向下，向里或向外移动。从动件通常联结机械的其他部分以完成要求的运动，从动件运动的方向取决于结构的位置也就是在机械中联结凸轮和从动轮。如果从动件与凸轮不接触，它将不能工作。
The faster the cam turns, the more rapid is the motion of the follower. The motion of the follower caused
by rotating the cam is exactly the same for each complete turn of the cam.
凸轮旋转越快，从动轮的运动越迅速，从动件的运动是由凸轮转动导致的并且这种运动与每个凸轮整个旋转运动是正好相反。
11. Belt drives
Text:
Belt drives offer a maximum of versatility[9v\:sE`tIlEtI] as power transmission elements. They allow the designer considerable flexibility[7fleksE5biliti] in location of driver and driven machinery, and
tolerances[5tClErEns] are not critical[5kritikEl] as is the case with gear drives. Another advantage of belt drives is that they reduce vibration and shock[FCk] transmission. Furthermore, belt drives are relatively[5relEtIvlI] quiet.
皮带传动装置作为传递动力的元件用途极广。这种装置使设计人员在确定主动机械与从动机械的位置时有相当大的灵活性，而且公差要求也不像齿轮传动装置那样严格。皮带传动另一个优点是可以减少振动及其传播。不仅如此，皮带传动噪声也比较小。
Large flat leather[5leTE] belts were in general use many years ago, when the usual practice was to use one large engine to driver several different pieces of machinery. Some leather belts are in use at this time as well as flat steel, rubber, plastic, and fabric[5fAbrik] belts. Light, thin flat belts are practical on high speed machinery where vibration may be a problem
用皮革制成的大的平皮带在许多年前曾用得很普遍，那时，通常是用一台大功率的发动机驱动好几台不同的机器。现在，除了平钢带、橡皮带、塑料带和布带外，一些皮革做的皮带还在使用。轻质薄型平皮带在高速机械上很实用，因为这里振动可能是一个问题。
V belts are probably the most common means of transmitting power between electric motor and driven machinery. Conventional[kEn5venFEnl] V belts are made of rubber. Most often, both driver and driven pulleys lie in the same vertical[5vE:tikEl] plane, and the speed ration is constant[5kCnstEnt].
三角皮带大概是在电动机与从动机械之间传递动力的最为普通的手段。普通的三角皮带用橡皮制造。通常，主动轮与从动轮位于同一个垂直面上，速比是恒定的。
Smooth flat belt and V belts depend on friction[5frikFEn] on the pulleys and some slippage[5slipidV] is inherent[in5hiErEnt] in their operation. Therefore, speed ratios are not precise[pri5sais]. Most heavy duty pulleys are made of cast iron or formed[fC:m] steel.
平皮带和三角皮带依靠在皮带轮上的摩擦进行传动，所以在传动中总是有一些滑动，因此，速比就不精确。大多数大的皮带轮是用铸铁和型钢制造的。
Note that the capacity[kE5pAsiti] of the belt drive is determined[di5tE:min] by the angle of wrap[rAp]
on the smaller pulley, and that this is particularly critical for drives involving pullets of greatly differing size, special closely together.
12. Keys and Springs
Text:
Keys are used to prevent[pri5vent] relative motion between a shaft and machine elements such as gears, pulleys, sprockets[5sprCkit], cams, levers[5li:vE, 5levE], flywheels[5flaiwi:l], impellers[im5pelE], and so on.
There are numerous[5nju:mErEs] kinds of key (some of which have been standardized[5stAndE7daizd]) for
various design requirement. The keys most frequently used are the square[skwZE] key, the tapered[5teipE] key,
and the woodruff[rQf] key.
Perhaps the most common of these torque-transmitting shaft-to-hub[hQb] connections are keys, of which
the most common type is the square key. Standard proportions[prE5pC:FEn] call for the key width to be approximately[EprRksI5mEtlI] one-forth the shaft diameter[dai5AmitE]. Keys are usually made of
cold-finished low-carbon steel, but heat-treated alloy steels are used when greater strength is required.
Mechanical springs[spriN] are used in machines to exert[i^5zE:t] force, to provide
flexibility[7fleksE5biliti] and to store or to absorb energy. In general, springs may be classified as either wire
springs or flat springs, although there are variation[7vZEri5eiFEn] within these divisions. Wire springs include
helical springs of round, square, or special-section wire and are made to resist tensile[5tensail],
compressure[kEm5preVE] or torsional[5tC:FEnEl] loads. Under flat springs are included the
cantilever[5kAntili:vE] and elliptical[i5liptikEl] types, the clocktype power-springs and the flat spring
washers[5wCFE], usually called Belleville springs.
In one word, springs are elastic members that exert forces (or torques) and absorb energy (which is
usually stored and later released[ri5li:s]). Springs are usually, but not necessarily, made of metal. Plastics can
be used when loads are light.
13. Screw
Screws 螺钉（丝）（螺纹连接）have been used as fasteners [5fB:snE] 紧固件for a long time 长期. As indicated in the section on single machine, a screw acts with a wedging[wedV] action 楔紧作用and consists
of a circular[5sE:kjulE] cylinder[5silindE] 圆柱(or truncated[5trQNkeit] cone[kEun]截锥体) with a helical
groove[^ru:v]螺旋槽in it. When used for fastening, all screws are provided with means for applying a torque (twisting moment) to them; this may consist of a square of hexagonal[hek`sA^EnEl] head 等边六角头（正六
边形）for a wrench[rentF]扳手, a head with a slot[slCt]槽or a cross-shaped recess[ri5ses]凹槽for a
screwdriver[5skru:draivE]改锥, a cylindrical head with a recess fitting a special wrench, or a slot or recess on
one end fitting a screwdriver or special wrench and no head.
螺钉已经被用来作为一种长期有效的紧固件。如本章的机床剖视图，螺钉的功能类似于一种楔紧作
用，由具有螺纹的圆柱体（或者圆锥体）组成。当用于固定作用时，所有的螺钉都提供了一种施加扭矩
的方式，这些方式有用于扳手的等边六角形，用于改锥的一字槽或者十字槽，用于配合特殊扳手的圆头
凹槽，或者甚至没有螺钉头但配合特殊改锥或特殊扳手的槽或凹坑。
Screws with screwdriver slots have heads of several shapes, such as flat, oval[5EuvEl], round, and
fillister[5filistE] 刨槽(cylindrical with a round top). Wood screws are tapered[5teipE]锥形, and self-tapping
screws 自攻螺丝have tapered ends and a variety of special points. The latter are usually hardened and cut or
form a mating[5meitiN] internal thread 匹配内螺纹when screwed into the proper size hole.
Screws with hexagonal heads are usually known as cap screws 帽螺钉. Screws with other types of heads
are also known as cap screws in the larger sizes and as machine screws 机加工螺丝in the small sizes. All of
these screws are used to clamp[klAmp] machine parts together when one of the parts has an internal thread. If
neither part is threaded 螺纹，a bolt[bEult]螺栓must be used: this consist of screw with a hexagonal head, a
nut[nQt]螺母(hexagonal ring with an internal thread), and usually a washer[5wCFE]垫圈(flat 扁ring).
带有六角形顶端的螺钉通常称为有头螺钉。这类螺钉用于当零件之一有内螺纹时把机
器的零件加紧在一起。如果零件上未切出螺纹，则必须使用螺栓。螺栓由带有六角形顶端的螺钉、螺母（是一个有内螺纹的六角环）、通常还有一个垫圈组成。
A stud[stQd] 柱头螺栓has threads on both ends and no means for turning. It is
permanently[5p\:mEntlI] screwed into one member and clamps by means of 靠a nut 螺母on the other end.
All of these fasteners stretch[stretF] 伸长when tightened[taIt]拉紧, and the tensile[5tensail] load 拉伸载荷created in this way clamps the members together.
Set screws 定位螺钉differ in form and function from the other type of screws. They are hardened 淬硬
and have cup, cone, oval, flat, and dog (cylindrical) ends or points. They are usually headless and are
frequently used as substitutes[5sQbstitju:t] for keys 键or in conjunction[kEn5dVQNkFEn] with 结合，连接keys in shaft-mounted members. The set screw fits in a threaded radial hole in the hub 轮毂, and the point is tightened down into a hole, a flat, or a dimple[5dimpl]小凹坑in the shaft or key. Set screws are stressed in compression 定位螺钉承受压缩应力and in action they create a helical wedge[wedV] 螺旋楔between the connected pates.
14. Shafts
As a machine component[kEm5pEunEnt]零件, a shaft is commonly a cylindrical bar 条that supports
and rotates with devices for receiving and delivering[di5livE] rotary motion and torque. The
crankshaft[5krANkFB:ft] 曲轴of a reciprocating[ri5siprEkeitiN] engine 往复移动式发动机receives its
rotary motion from each of the cranks[krANk]曲柄, via the pistons 活塞and connecting rod[rCd] 连杆(the
slider-crank mechanisms[5mekEnizEm]曲柄滑块机构), and delivers it by means of couplings [5kQpliN]联轴器, gears, chains[tFein], or belts to the transmission 变速箱, camshaft 凸轮轴, pumps[pQmp], and other devices. The camshaft[5kAmFB:ft], driven by a gear or chain from the crankshaft, has only one receiver or
input, but each cam on the shaft delivers rotary motion to the valve-actuating[5Aktjueit] mechanisms 阀驱动
机构.
轴作为机械零件通常是一根圆柱形杆，用来支撑部件并随部件一起传动以接受和传递转动和扭矩。
往复式发动机的曲轴接受每一根曲轴通过活塞和连杆（滑块曲柄机构）传来的转动，并通过联轴器、齿轮、链条或皮带把转动传递到变速箱、凸轮轴、泵和其它装置。由曲轴通过齿轮或链条驱动的凸轮轴只
有一根受力轴即输入轴，但轴上的每一个凸轮都能把转动传递给气门的阀驱动机构。
An axle[5Aksl]车轴is usually defined as a stationary[5steiF(E)nEri] 固定cylindrical member on which wheels and pulleys滑轮can rotate, but the rotating shaft that drive the rear wheels 后轮of an automobile are
also called axles, no doubt 毫无疑问a carryover 传承from horse-and-buggy[5bQ^i] 马拉车days 时代. It is common practice 通常习惯于to speak of 说成是short shafts on machines as spindles[5spindl]心轴, especially tool-carrying or work-carrying shafts on machine-tool 机床，工具机.
轮轴通常的定义是车轮和皮带轮能在其上旋转的一根固定的圆柱形构件，但驱动汽车后轮的旋转轴
也叫轮轴，这可能是从过去马车时代传下来的。通常习惯上把机器上的短轴叫做主轴（或心轴），特别
是指机床上安装刀具和工件的轴。
In operation, shafts are subjected 承受to a shearing stress 应力, whose magnitude[5mA^nitju:d]
depends on the torque and the dimensions of the cross section. This stress is a measure of the resistance that
the shaft material offers to the applied torque. All shafts that transmit a torque are subjected to
torsional[5tC:FEnEl] shearing stress 扭转剪切力.
轴在转动时承受剪应力，其大小取决于扭转和断面的尺寸。这个剪应力是轴的材料对作用扭矩所产
生的抗力的一种量度。所有传递扭矩的轴都承受扭转剪应力。
In addition to the shearing stresses, twisted 扭曲shafts are also subjected to shearing
distortions[dis5tC:FEn]扭曲变形. The distorted state is usually defined by the angle of twist 扭转角per unit length, i.e., the rotation of one cross section of a shaft relative to another cross section at a unit distance from it.
轴的某一截面相对于间隔一个单位长度的另一截面的旋转角度。
除剪应力之外，传递扭转的轴还会产生剪切变形。扭转的状态通常用每单位长度的扭转角来表示，即用轴的某一截面所转过的角度来表示。
15. Bearings
A bearing[5bZEriN] 轴承is a connector[kE5nEktE(r)] 连接器that permits the connected members to either rotate or translate[trAns5leit] (move to and fro 往复) relative to one another but prevent them from separating in the direction in which loads are applied. In many cases one of the members is fixed, and the bearing acts as a support for the moving member.
The relative motion in bearings is always opposed[E5pEuz]阻碍by friction, and the work done in overcoming[7EuvE5kQm] 克服friction is lost power in all machines. Consequently[5kRnsIkwEntlI], much thought and effort have been devoted[di5vEut] to 做出很大努力the development of bearings with minimum friction. In all bearings there are two surfaces (one belonging to each of the connected parts) that move relative to one another. To minimize friction, the co-acting 共同作用surfaces may be partially[5pB:FElI] or completely separated by a film of liquid or gas; these are known as sliding-contact bearings 滑动轴承. The surfaces may
be separated also by an assemblage[E5semblidV]集合of rolling elements 滚动单元such as balls and
rollers[5rEulE]滚柱; these are known as roll-contact bearing.滚动轴承
Sliding bearings are the simplest to construct and, considering the multitude[5mQltitju:d] of 多数
pin-jointed 铰接devices and structures in use, are probably the most commonly used.
The essential[i5senFEl]基本parts of a ball bearing——the inner and outer ring, the balls 滚珠, and the separator 分离器——are shown in figure[5fi^E]. The inner ring is mounted on a shaft and has a groove in which the balls ride 球被支撑. The outer ring is usually the stationary[5steiF(E)nEri] part of the bearing and also contains a groove to guide and support the balls. The separator prevents contact between the balls and thus reduces friction, wear, and noise from the regions where severe[si5viE] sliding conditions would occur 可能发生严重滑动摩擦情况的区域. In a few applications where operating conditions are mild, the rings and separator can be omitted and loose balls interposed[7intE(:)5pEuz] 插入between the shaft and housing[5hauziN]外壳. This type of bearing is sometimes found in bicycles. The vast majority[mE5dVCriti] of 绝大多数ball bearings, however, are preassembled[5pri:E5sembl] units consisting of four elements 是由四个零件预装的部件. There are many types of bearings because of variations[7vZEri5eiFEn] in the design of rings and separators and in the number of balls. They can be divided into classes 种类according to their function: those that support a combination of a radial[5reidjEl] load 径向载荷, those that support a thrust[WrQst] load 推力载荷, or those that support a combination of thrust and radial loads. The last type is termed[tE:m]
"angular[5AN^julE]-contact bearing 角接触轴承."
In deep-groove ball bearings 深沟球轴承, the races[reis]沟槽are approximately one fourth as deep as
the ball diameter[dai5AmitE]. A cross section of the ball and outer ring of a deep-groove ball bearing is shown
in figure. Although deep-groove ball gearings are designed to carry a radial load, they perform[pE5fC:m] well under a combined radial and thrust load. For this reason, this is the most widely used type of ball bearing.
16. Couplings
A coupling[5kQpliN] is a device for connecting the ends of adjacent[E5dVeisEnt] shafts. In machine construction, couplings are used to effect 实现a semipermanent[9semI`p\:mEnEnt,9semaI-] connection between adjacent rotating shafts. The connection is permanent in the sense that it is not meant to be broken during the useful life of the machine, but it can be broken and restored[ris5tC:] in an emergency[i5mE:dVnsi]
or when worn[wC:n] parts are replaced.
联轴器是一种联接两根相邻轴末端的装置。机械构件中，联轴器可以用来实现相邻两根旋转轴的半永久性联接。在机器的正常使用周期内，联轴器通常不必拆开，在这个意义上可以说联轴器的联接是永
久性的，而在紧急情况下或者需要更换已磨损的零件时，可先把联轴器拆开并重新联接上。
There are several types of shaft couplings; their characteristics[7kAriktE5ristik] depend on the purpose
for which they are used. If an exceptionally[ik5sepFEnl] long shaft is required for a line shaft in a manufacturing plant[plB:nt] or a propeller[prE5pelE]螺旋桨shaft on a ship, it is made in sections that are coupled[5kQpl] together with rigid[5ridVid] couplings. A common type of rigid coupling consists of two mating radial flanges[flAndV]法兰(disks) that are attached by key-driven hubs to the ends of adjacent shaft sections
and bolted together through the flanges to form a rigid connection. Alignment[E5lainmEnt] of the connected shafts is usually effected by means of a rabbet[5rAbit] joint 槽口on the face of the flanges, i.e., a short cylindrical projection[prE5dVekFEn] 凸起部分on the face of one flange fits snugly[5snQ^li] in a circular recess on the face of the other flange。
联轴器有几种类型，其特性随其用途而定。如果制造厂中或者船舶的螺旋桨需要一根特别长的轴时，可以分段制造，然后采用刚性联轴器将这些轴联接起来。常用的刚性联轴器包括两个匹配的径向法兰（盘），他们是通过靠键传动的轮毂来连接到相邻两轴的两端，然后用螺栓穿过法兰联接起来形成了刚性联接。相互联接的两轴是靠法兰面上的槽口来对准的，也就是说，在其中一个法兰面上的短圆柱上的凸起部分与另一个法兰面上的圆形凹进部分相互紧贴。
In connecting shafts belonging to separate devices (such as an electric motor and a gear-box), precise aligning[E5lainiN] of the shafts is difficult and a flexible coupling is used. This coupling connects the shafts in such a way as to 为了minimize the harmful effects of shaft misalignment[5misElainmEnt]轴线偏离.
Flexible couplings also permit the shafts to deflect[di5flekt] under their separate systems of loads and to move freely (float) in the axial direction without interfering[9IntE`fIErIN] with one another. Flexible couplings can also serve to reduce the intensity[in5tensiti] of shock loads and vibrations transmitted from one shaft to another.
在把两个属于不同设备（如电机和变速箱）的轴联接起来时，要把这些轴精确对准是很困难的，因此可以采用弹性联轴器。采用这种联轴器联接两轴时，可以把由于轴联接中轴线不重合所造成的损害降到最小。弹性联轴器还可允许被联接的轴在各自载荷系统中偏斜和在轴向上自由移动（浮动），而不相互干扰。弹性联轴器还能用来减小从一根轴传到另一根轴的冲击载荷和振动强度。
The flexibility[7fleksE5biliti] provided by a coupling may be only spatial[5speiFEl], or it may be both spatial and resilient[ri5ziliEnt] (springy[5spri:Ni]); in other words the coupling may compensate[5kCmpEnseit] for shaft misalignment but provide no resilience, or it may be resilient and provide also for a small amount of misalignment.
联轴器的适应性（弹性）可能只是空间上的（滚珠联接），或者可能既有空间上的也具有回弹性（弹性圈联接），换言之，就是联轴器可以补偿轴线的不重合性，但不提供回弹性，或者即提供回弹性也在轴线不重合时，提供小量补偿。
17. Clutches
A clutch[klQtF] is a device for quickly and easily connecting or disconnecting a rotatable[5rEuteitEbl] shaft and a rotating coaxial[kEu5AksEl] shaft. Clutches are usually placed between the input shaft to a
machine and the output shaft from the driving motor, and provide a convenient[kEn5vi:njEnt] means for
starting and stopping the machine and permitting the driver motor or engine to be started in an
unloaded[5Qn5lEud] state.
离合器是一个用来使从动轴与位于同一轴线上的主动轴进行快速和顺利的联接或脱开的装置。离合器通常位于机器的输入轴和驱动电机的输出轴之间，以提供一个方便地启动和停止机器的手段，并使得驱动电机或发动机在无荷载的状态下启动。
The rotor (rotating member) in an electric motor has rotational[rEu5teiFEnEl] inertia[i5nE:FjE], and a torque is required to bring it up to speed when the motor is started. If the motor shaft is rigidly connected to a load with a large rotational inertia, and the motor is started suddenly by closing a switch[switF], the motor
may not have sufficient torque capacity[kE5pAsiti] to bring the motor shaft up to speed before the
windings[5waindiN] in motor are burned out by the excessive[ik5sesiv] current demands. A clutch between the motor and the load shafts will restrict the starting torque on the motor to that required to accelerate the rotor
and parts of the clutch only.
电机中的转子有转动惯量，当电机启动时需要一个转矩带动其运转。如果电动机的轴与具有很大转动惯量的负载刚性地联接在一起，当合上开关使电动机突然启动时，有可能在电动机没有来得及产生足够的扭矩，使电动机的轴达到应有的转速之前，电动机内的线圈就会因为过大的电流而被烧毁。电机和负载轴之间的离合器会限制电机的启动转矩只到所需要的加速转子和离合器部件的数值。
On some machine tools, it is convenient to let the driving motor run continuously and to start and stop the machine by operating a clutch. Other machine tools receive the power from belts driven by pulleys on intermediate[7intE5mi:djEt] shafts that are themselves driven by belts from long lineshafts[5lain7FB:ft] that serve a group of machine. Two pulleys that can be connected to the intermediate shaft by clutches, and driven
in opposite directions by open and crossed belts from the line shaft, can provide forward and reverse[ri5vE:s] rotation for the machine.
在某些机床上，通过操作离合器使驱动电机连续运转、启动和停止是非常方便的。其他机床上，机床是通过皮带获得动力，这些皮带是由中间轴上的滑轮来驱动，而中间轴又是通过总轴上的皮带来驱动，驱动这些中间轴的总轴同时还驱动其他的机器。两个滑轮可以通过离合器联接到中间轴上，通过总轴的开口式或者交叉式皮带驱动使得两滑轮以相反的方向转动，同时还能为机床提供正向和反向转动。
18. Brakes
Basically, brakes[breik] 制动器are devices for controlling the flow[flEu] of motion in machine, and in this respect[ris5pekt] they resemble[ri5zembl] clutches; clutches start the flow while brakes arrest[E5rest] it. Before the engagement[in5^eidVmEnt] of a clutch or a brake, one of the two members in the device is moving while the other is stationary; after the engagement of a clutch both members are moving at the same speed,
while after the application[7Apli5keiFEn] of a brake the moving member is either slowed down or
stationary[5steiF(E)nEri]. In both cases the desired effects are produced by devices that are so alike, structurally[5strQktFErEl], that they can sometimes serve in either capacity[kE5pAsiti].
基本上，制动器是一种控制机器中运动部件运动状态的装置，在这个方面，它与离合器类似，离合器激发运动，而制动器阻止其运动。在离合器或者制动器啮合之前，连接的两个部件中其中一个在移动而另外一个保持不动，在离合器啮合后，两个部件就以相同的速度移动，但使用制动器后，移动的部件要么减速下来，要么静止不动。不论哪种情况，由制动器或者离合器在结构上产生的效果如此相似，以至于他们有时可以执行任意一种功能。
In arresting the motion of bodies, brakes must be capable of absorbing kinetic[kai5netik] energy. Even when acting on translating bodies (like automobiles) most brakes are designed to act on rotating mechanical elements and to absorb energy either mechanically, hydraulically[hai5drC:lik], or electrically[I`lektrIkElI]. Mechanical brakes are the most common: they dissipate[5disipeit] kinetic energy in the form of heat generated
by mechanical friction between a rotating metallic[mi 5tAlik] element and a nonrotating friction element,
when they are brought in contact by either mechanical, hydraulic, pneumatic[nju(:)5mAtik], or electrical means. The material in the friction element may be organic[C:5^Anik], metallic[mi 5tAlik], or
ceramic[si5rAmik]. Organic materials with an asbestos[Az5bestRs] bases are satisfactory for the
majority[mE5dVCriti] of applications. When service requirements are severe, however, the heat generated may cause "fading[5feidiN]" (a drop in braking effectiveness[i5fektivnis] caused by a reduction in the
coefficient[kEui5fiFEnt] of friction). In such cases, sintered[5sintEd] metallic linings[5lainiN] are
preferred[prI`f\:d] because of their high thermal[5WE:mEl] conductivity[7kCndQk5tiviti] and freedom from fading. By adding ceramic particles[5pB:tikl] to sintered metallic linings, extremely hard and
化学专业英语(修订版)翻译
01 THE ELEMENTS AND THE PERIODIC TABLE 01 元素和元素周期表 The number of protons in the nucleus of an atom is referred to as the atomic number, or proton number, Z. The number of electrons in an electrically neutral atom is also equal to the atomic number, Z. The total mass of an atom is determined very nearly by the total number of protons and neutrons in its nucleus. This total is called the mass number, A. The number of neutrons in an atom, the neutron number, is given by the quantity A-Z. 质子的数量在一个原子的核被称为原子序数,或质子数、周淑金、电子的数量在一个电中性原子也等于原子序数松山机场的总质量的原子做出很近的总数的质子和中子在它的核心。这个总数被称为大量胡逸舟、中子的数量在一个原子,中子数,给出了a - z的数量。 The term element refers to, a pure substance with atoms all of a single kind. T o the chemist the "kind" of atom is specified by its atomic number, since this is the property that determines its chemical behavior. At present all the atoms from Z = 1 to Z = 107 are known; there are 107 chemical elements. Each chemical element has been given a name and a distinctive symbol. For most elements the symbol is simply the abbreviated form of the English name consisting of one or two letters, for example: 这个术语是指元素,一个纯物质与原子组成一个单一的善良。在药房“客气”原子的原子数来确定它,因为它的性质是决定其化学行为。目前所有原子和Z = 1 a到Z = 107是知道的;有107种化学元素。每一种化学元素起了一个名字和独特的象征。对于大多数元素都仅仅是一个象征的英文名称缩写形式,一个或两个字母组成,例如: oxygen==O nitrogen == N neon==Ne magnesium == Mg
汽车专业英语翻译综合
第一章汽车总论 1)Today’s average car contains more than 15,000 separate, individual parts that must work together. These parts can be grouped into four major categories: body, engine, chassis and electrical equipment 。P1 现在的车辆一般都由15000多个分散、独立且相互配合的零部件组成。这些零部件主要分为四类：车身、发动机、底盘和电气设备。 2)The engine acts as the power unit. The internal combustion engine is most common: this obtains its power by burning a liquid fuel inside the engine cylinder. There are two types of engine: gasoline (also called a spark-ignition engine) and diesel (also called a compression-ignition engine). Both engines are called heat engines; the burning fuel generates heat which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the power train. P3 发动机作为动力设备，常见的类型是内燃机，其原理是通过发动机缸内的液体燃料燃烧而产生能量。发动机可分为两类：汽油机（点燃式）和柴油机（压燃式），都属于热力发动机。燃料燃烧产生热量使缸内气压上升，产生的能量驱动轴旋转，并传递给动力传动系。 第二章内燃机 1)Power train system: conveys the drive to the wheels 2)Steering system: controls the direction of movement 3)Suspension system: absorbs the road shocks 4)Braking system: slows down the vehicle P4 传动系把发动机输出的扭矩传递给驱动轮。传动系包括离合器（对应机械变速器）或液力变矩器（对应液力自动变速器）、变速器、驱动轴、主减速器、差速器和驱动桥。 5)Drum brakes have a drum attached to the wheel hub, and braking occurs by means of brake shoes expanding against the inside of the drum. With disc brakes, a disc attached to the wheel hub is clenched between two brake pads. P6 鼓式制动器的制动鼓和轮毂连接，制动蹄张开压紧制动鼓内侧从而产生制动。在盘式制动器上，连着轮毂的制动盘被紧紧夹在两个制动块之间。 1)Linking the piston by a connecting rod to a crankshaft causes the gas to rotate the shaft through half a turn.The power stroke"uses up"the gas,so means must be provided to expel the burnt gas and recharge the cylinder with a fresh petrol-air mixture:this control of gas movement is the duty of the valves;An inlet valve allows the mixture to enter at the right time and an exhaust valve lets out the burnt gas after the gas has done its job . P10 活塞通过连杆和曲轴连接，使得气体带动曲轴旋转半圈。作功冲程耗尽了所有的气体，这样就必须采取相应的措施排出废气并且向气缸内充入新的可燃混合气：气体的运动由气门来控制。进气门使可燃混合气在恰当的时刻进入气缸，排气门使燃烧后的废气排出气缸。 2)The spark-ignition engine is an internal-combustion engine with externally supplied in ignition,which converts the energy cntained in the fuel to kinetic energy.The cycle of operations is spread over four piston strokes. To complete the full cycle it takes two revolutions of the crankshaft. P11 火花点火式发动机是由外部提供点火的内燃机，从而将含在燃料内的能量转化成动能。发动机的一个工作循环分布在活塞的四个行程中，一个完整的工作循环曲轴需要转动两圈。 3)The oil pump in the lubricating system draws oil from the oil pan and sends it to all working parts in the engine. The oil drains off and runs down into the pan. Thus,there is constant circulation of oil between the pan and the working parts of the engine. P15
电气工程及其自动化专业英语第二章课文翻译
第二章第一篇 To say that we live in an age of electronics is an understatement. From the omnipresent integrated circuit to the equally omnipresent digital computer, we encounter electronic devices and systems on a daily basis. In every aspect of our increasingly technological society— whether it is science, engineering, medicine, music, maintenance, or even espionage—the role of electronics is large, and it is growing. 谈论关于我们生活在一个电子学时代的论调是一种空泛的论调。从无处不在的集成电路到同样无处不在的数字计算机，我们在日常活动中总会遇到电子设备和电子系统。在我们日益发展的科技社会的方方面面——无论是在科学、工程、医药、音乐、维修方面甚至是在谍报方面——电子学的作用是巨大的，而且还将不断增强。 In general, all of the tasks with which we shall be concerned can be classified as "signal-processing“tasks. Let us explore the meaning of this term 一般说来，我们将要涉及到的工作被归结为“信号——处理”工作，让我们来探究这个术语的含义吧。 A signal is any physical variable whose magnitude or variation with time contains information. This information might involve speech and music, as in radio broadcasting, a physical quantity such as the temperature of the air in a room, or numerical data, such as the record of stock market transactions. The physical variables that can carry information in an electrical system are voltage and current. When we speak of "signals", therefore, we refer implicitly to voltages or currents. However, most of the concepts we discuss can be applied directly to systems with different information-carrying variables. Thus, the behavior of a mechanical system (in which force and velocity are the variables) or a hydraulic system (in which pressure and flow rate are the variables) can often be modeled or represented by an equivalent electrical system. An understanding of the behavior of electrical systems, therefore, provides a basis for understanding a much broader range of phenomena. 信号就是其与时间有关的量值或变化包含信息的任何物理变量。这种信息或许像无线电广播的演讲和音乐，或许是像室内温度的物理量，或许像股市交易记录的数字数据。在电气系统中能够载有信息的物理变量是电压和电流。因此当我们谈到“信号”，我们不言而喻指的是电压和电流，然而，我们要讨论的大多数概念是可以被直接应用于载有不同信息的变量的系统，因此，一个机械系统（在这个系统中力和速度是其变量）或者液压系统（在这个系统中压力和流速是其变量）的性能通常可以用一个等效的电气系统来模拟或表示。因此，我们对于电气系统性能的理解为理解更宽领域的现象打下了一个基础。 A signal can carry information in two different forms. In an analog signal the continuous variation of the voltage or current with time carries the information. An example, in Fig.2-l, is the voltage produced by a thermocouple pair when the two junctions are at different temperatures. As the temperature difference between the two junctions varies, the magnitude of the voltage across the thermocouple pair also varies. The voltage thus provides an analog representation of the temperature difference. 一个信号可以以两种形式来承载信息。在一个模拟信号中电压或电流随时间而产生的连续变化载有信息。在图2-1中，当一对热电偶的接头处于不同的温度时由热电偶所产生的电压就是一个例子。当两个接头之间的温度差改变时，一对热电偶两端的电压也将改变。于是电压就提供了温度差的模拟表现形式 The other kind of signal is a digital signal. A digital signal is one that can take on values within two discrete ranges. Such signals are used to represent ON-OFF or YES-NO information. An ordinary household thermostat delivers a digital signal tocontrol the furnace. When the
大学英语精读1课文翻译
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《化学工程与工艺专业英语》课文翻译 完整版
Unit 1 Chemical Industry 化学工业 1.Origins of the Chemical Industry Although the use of chemicals dates back to the ancient civilizations, the evolution of what we know as the modern chemical industry started much more recently. It may be considered to have begun during the Industrial Revolution, about 1800, and developed to provide chemicals roe use by other industries. Examples are alkali for soapmaking, bleaching powder for cotton, and silica and sodium carbonate for glassmaking. It will be noted that these are all inorganic chemicals. The organic chemicals industry started in the 1860s with the exploitation of William Henry Perkin‘s discovery if the first synthetic dyestuff—mauve. At the start of the twentieth century the emphasis on research on the applied aspects of chemistry in Germany had paid off handsomely, and by 1914 had resulted in the German chemical industry having 75% of the world market in chemicals. This was based on the discovery of new dyestuffs plus the development of both the contact process for sulphuric acid and the Haber process for ammonia. The later required a major technological breakthrough that of being able to carry out chemical reactions under conditions of very high pressure for the first time. The experience gained with this was to stand Germany in good stead, particularly with the rapidly increased demand for nitrogen-based compounds (ammonium salts for fertilizers and nitric acid for explosives manufacture) with the outbreak of world warⅠin 1914. This initiated profound changes which continued during the inter-war years (1918-1939). 1．化学工业的起源 尽管化学品的使用可以追溯到古代文明时代，我们所谓的现代化学工业的发展却是非常近代（才开始的）。可以认为它起源于工业革命其间，大约在1800年，并发展成为为其它工业部门提供化学原料的产业。比如制肥皂所用的碱，棉布生产所用的漂白粉，玻璃制造业所用的硅及Na2CO3. 我们会注意到所有这些都是无机物。有机化学工业的开始是在十九世纪六十年代以William Henry Perkin 发现第一种合成染料—苯胺紫并加以开发利用为标志的。20世纪初，德国花费大量资金用于实用化学方面的重点研究，到1914年，德国的化学工业在世界化学产品市场上占有75%的份额。这要归因于新染料的发现以及硫酸的接触法生产和氨的哈伯生产工艺的发展。而后者需要较大的技术突破使得化学反应第一次可以在非常高的压力条件下进行。这方面所取得的成绩对德国很有帮助。特别是由于1914年第一次世界大仗的爆发，对以氮为基础的化合物的需求飞速增长。这种深刻的改变一直持续到战后（1918-1939）。 date bake to/from: 回溯到 dated: 过时的，陈旧的 stand sb. in good stead: 对。。。很有帮助
电气工程及其自动化专业英语第五章课文翻译
Most people can formulate a mental picture of a computer, but computers do so many things and come in such a variety of shapes and sizes that it might seem difficult to distill their common characteristics into an all-purpose definition. At its core, a computer is a device that accepts input, processes data, stores data, and produces output, all according to a series of stored instructions. Computer input is whatever is put into a computer system. Input can be supplied by a person, by the environment, or by another computer. Examples of the kinds of input that a computer can accept include the words and symbols in a document, numbers for a calculation, pictures, temperatures from a thermostat, audio signals from a microphone, and instructions from a computer program. An input device, such as a keyboard or mouse, gathers input and transforms it into a series of electronic signals for the computer. In the context of computing, data refers to the symbols that represent facts, objects, and ideas. Computers manipulate data in many ways, and we call this manipulation processing. The series of instructions that tell a computer how to carry out processing tasks is referred to as a computer program, or simply a "program." These programs form the software that sets up a computer to do a specific task. In a computer, most processing takes place in a component called the central processing unit (CPU), which is sometimes described as the"brain" of the computer. A computer stores data so that it will be available for processing. Most computers have more than one location for storing data, depending on how the data is being used. Memory is an area of a computer that temporarily holds data that is waiting to be processed, stored, or output. Storage is the area where data can be left on a permanent basis when it is not immediately needed for processing. Output is the results produced by a computer. Some examples of computer output include reports, documents, music, graphs, and pictures. An output device displays, prints, or transmits the results of processing. Computers are versatile machines, which are able to perform a truly amazing assortment of tasks, but some types of computer are better suited to certain tasks than other types of computers. Computers can be categorized as personal computer, handheld computers, workstations, mainframes, supercomputers , and servers. 大多数人可以制订一个电脑精神的图片，但电脑做很多事情，出现这样的形状和大小不同，它似乎难以提炼成一个全能的定义，它们的共同特点。在其核心，一台计算机是一种装置，它接受输入，处理数据，存储数据，并产生输出，根据对所有存储一系列指示。 什么是计算机输入到计算机系统的压力。输入可提供的一人，由环境，或由另一台计算机。对输入的各种例子，一个计算机可以接受包括文字和符号的文件，规定计算，图片，从恒温器的温度数字，音频信号从一个麦克风，从电脑程序指令。一个输入设备，如键盘或鼠标，集输和转换成一个电子信号的计算机的一系列。 在计算中，数据是指以符号代表的事实，对象和想法。计算机操作在很多方面的数据，我们称之为操作处理。一系列的指令，告诉计算机如何进行处理任务，被称为一个计算机程序，或只是一个“程序”。这些方案形成了软件，建立了计算机做特定的任务。在计算机中，大部分处理发生在一个组件的地方称为中央处理单元（CPU），有时为“大脑的计算机”来形容。 计算机存储数据，以便它会被用作处理可用。大多数计算机有多个用于存储数据的位置，这取决于数据如何被使用。内存是计算机的一个领域，数据是暂时持有等待处理，存储或输出。在数据存储，是可以在一个地区长期离开时，没有立即处理所需。 输出是由电脑产生的结果。电脑输出的一些例子包括报告，文件，音乐，图形，图片。输出设备显示，打印，或传送的处理结果。 电脑是多功能机，它能够执行各种各样的任务十分惊人，但某些类型的计算机更适合比其他类型的计算机的某些任务。计算机可以被归类为个人电脑，掌上电脑，工作站，大型机，超级计算机和服务器。
[实用参考]大学英语精读第三版第四册课文及课文翻译.doc
Unit1 Twocollege-ageboPs,unawarethatmakingmonePusuallPinvolveshardwork,aretemptedbPanadvertis ementthatpromisesthemaneasPwaPtoearnalotofmoneP.TheboPssoonlearnthatifsomethingseemstog oodtobetrue,itprobablPis. 一个大学男孩，不清楚赚钱需要付出艰苦的劳动，被一份许诺轻松赚大钱的广告吸引了。男孩们很快就明白，如果事情看起来好得不像真的，那多半确实不是真的。BIGBUCKSTHEEASPWAP轻轻松松赚大钱"Pououghttolookintothis,"Isuggestedtoourtwocollege-agesons."ItmightbeawaPtoavoidtheindignitP ofhavingtoaskformonePallthetime."Ihandedthemsomemagazinesinaplasticbagsomeonebadhungon ourdoorknob.AmessageprintedonthebagofferedleisurelP,lucrativework("BigBuckstheEasPWaP!")o fdeliveringmoresuchbags. “你们该看看这个，”我向我们的两个读大学的儿子建议道。“你们若想避免因为老是向人讨钱而有失尊严的话，这兴许是一种办法。”我将挂在我们门把手上的、装在一个塑料袋里的几本杂志拿给他们。塑料袋上印着一条信息说，需要招聘人投递这样的袋子，这活儿既轻松又赚钱。（“轻轻松松赚大钱!”） "Idon'tmindtheindignitP,"theolderoneanswered.“我不在乎失不失尊严，”大儿子回答说。"Icanlivewithit,"hisbrotheragreed.“我可以忍受，”他的弟弟附和道。"Butitpainsme,"Isaid，"tofindthatPoubothhavebeenpanhandlingsolongthatitnolongerembarrassesPou."“看到你们俩伸手讨钱讨惯了一点也不感到尴尬的样子，真使我痛心，”我说。TheboPssaidthePwouldlookintothemagazine-deliverPthing.Pleased,Ilefttownonabusinesstrip.BPmi dnightIwascomfortablPsettledinahotelroomfarfromhome.Thephonerang.ItwasmPwife.Shewantedt oknowhowmPdaPhadgone.孩子们说他们可以考虑考虑投递杂志的事。我听了很高兴，便离城出差去了。午夜时分，我已远离家门，在一家旅馆的房间里舒舒服服住了下来。电话铃响了，是妻子打来的。她想知道我这一天过得可好。 "Great!"Ienthused."HowwasPourdaP?"Iinquired.“好极了!”我兴高采烈地说。“你过得怎么样?”我问道。 "Super!"Shesnapped."Justsuper!Andit'sonlPgettingstarted.Anothertruckjustpulledupoutfront."“棒极了!”她大声挖苦道。“真棒!而且这还仅仅是个开始。又一辆卡车刚在门前停下。”"Anothertruck?"“又一辆卡车?” "Thethirdonethisevening.ThefirstdeliveredfourthousandMontgomerPWards.Thesecondbroughtfour thousandSears,Roebucks.Idon'tknowwhatthisonehas,butI'msureitwillbefourthousandofsomething.S incePouareresponsible,IthoughtPoumightliketoknowwhat'shappening.“今晚第三辆了。第一辆运来了四千份蒙哥马利-沃德百货公司的广告；第二辆运来四千份西尔斯-罗伯克百货公司的广告。我不知道这一辆装的啥，但我肯定又是四千份什么的。既然这事是你促成的，我想你或许想了解事情的进展。” WhatIwasbeingblamedfor,itturnedout,wasanewspaperstrikewhichmadeitnecessarPtohand-deliverth eadvertisinginsertsthatnormallPareincludedwiththeSundaPpaper.ThecompanPhadpromisedourboPs $600fordeliveringtheseinsertsto4,000housesbPSundaPmorning.我之所以受到指责，事情原来是这样：由于发生了一起报业工人罢工，通常夹在星期日报纸里的广告插页，必须派人直接投送出去。公司答应给我们的孩子六百美金，任务是将这些广告插页在星期天早晨之前投递到四千户人家去。 "Pieceofcake!"ouroldercollegesonhadshouted.“不费吹灰之力!”我们上大学的大儿子嚷道。"SiGhundredbucks!"Hisbrotherhadechoed,"Andwecandothejobintwohours!"“六百块!”他的弟弟应声道，“我们两个钟点就能干完!” "BoththeSearsandWardadsarefournewspaper-sizepages,"mPwifeinformedme."TherearethirtP-twot housandpagesofadvertisingonourporch.Evenaswespeak,twobigguPsarecarrPingarmloadsofpaperup thewalk.Whatdowedoaboutallthis?"“西尔斯和沃德的广告通常都是报纸那么大的四页，”妻子告诉我说，“现在我们门廊上堆着三万二千页广告。就在我们说话的当儿，两个大个子正各抱着一大捆广告走过来。这么多广告，我们可怎么办?”"JusttelltheboPstogetbusP,"Iinstructed."TheP'recollegemen.TheP'lldowhatthePhavetodo."“你让孩子们快干，”我指示说。“他们都是大学生了。他们自己的事得由他们自己去做。”AtnoonthefollowingdaPIreturnedtothehotelandfoundanurgentmessagetotelephonemPwife.Hervoic
汽车专业英语翻译
About car engine Of all automobile components,an automobile engie is the most complicated assembly with dominant effects on the function of an autombile.So, the engine is generally called the"heat"of an automobile. 在汽车的所有部件中，汽车发动机是最复杂的组件，其对整车性能有着决定性的作用。因而发动机往往被称作发动机的“心脏”。 There are actually various types of engines such as electric motors,stream engines,andinternal combustion engines.The internal combustion engines seem to have almost complete dominance of the automotive field.The internal combustion engine,as its name indicates,burns fuel within the cylinders and converts the expanding force of the combustion into rotary force used to propel the vehicle. 事实上，按动力来源分发动机有很多种，如电动机、蒸汽机、外燃机等。然而内燃机似乎在发动机领域有着绝对的统治地位。就像其字面意思一样，内燃机的染料在气缸内燃烧，通过将燃烧产生气体的膨胀力转换成转动力来驱动发动机前进。 Engine is the power source of the automobile.Power is produced by the linear motion of a piston in a cylinder.However,this linear motion must be changed into rotary motion to turn the wheels of cars or trucks.The puston attached to the top of a connecting rod by a pin,called a piston pin or wrist pin.The bottom of the connecting rod is attached to the crankshaft.The connecting rod transmits the up-and-down motion of the piston to the crankshaft,which changes it into rotary motion.The connecting rod is mounted on the crankshaft with large bearings called rod bearing.Similar bearings, called main bearings,are used to mount the crankshaft in the block. 发动机是整部车的动力来源。能量来自于活塞在气缸内的（往复）直线运动。然而这种（往复）直线运动必须要转换成旋转运动才能驱动车轮。活塞与连杆通过一个销来连接，这个销称为活塞销。连杆的下部连接于曲拐。连杆把活塞的上下往复运动传递给曲拐，从而将往复直线运动转变成旋转运动。连杆和曲拐的连接使用大的轴承，称之为连杆轴承，类似的轴承也用于将曲轴连接到机体，称之为主轴承。 They are generally two different types of cooling system:water-cooling system and air-cooling system.Water-cooling system is more common.The cooling medium, or coolant, in them is either water or some low-freezing liquid, called antifreeze.A water-cooling system consists of the engine water jacket, thermostat, water pump, radiator, radiator cap, fan, fan drive belt and neccessary hoses. 主要有两种类型的冷却系统：水冷和风冷。水冷系统更为普遍。系统所用冷却介质或是冷却液常委水或其他低凝固点液体，称为抗凝剂。一个完整的水冷系统包括机体水套，节温器，水泵，散热器，散热器罩，风扇，风扇驱动皮带和必需的水管。 A water-cooling system means that water is used as a cooling agent to circulate through the engine to absorb the heat and carry it to the radiator for disposal.The ebgine is cooled mainly through heat transfer and heat dissipation.The heat generated by the mixture burned in the engine must be transferred from the iron or aluminum cylinder to the waterin the water jacket.The outside of the water jacket dissipates some of the heat to the air surrounding it, but most of the heat is carried by the cooling water to the radiator for dissipation.When the coolant temperature in the system reaches 90°,the termostat valve open fully, its slanted edge shutting off