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] 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.

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） [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 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