专业英语翻译

Spindles come in several quality ratings and are supported in headstocks by three to five beanings. Since the accuracy of the work done on a lathe depends on the axis of rotation of the spindle holding the workpiece, the spindle and all its accessories must be built and assembled with the greatest possible care.

在床头箱中，主轴由三到五个轴承支撑着，因为车床上工件的精度取决于主轴夹挡的附件的轴心，所以主轴和其它附件都必须尽可能仔细的建造和安装。

Cutting round holes in metal stock is one of the most common operations performed in the machine shop. Very few metal pieces go through a factory without having holes drilled in them. Later operations are often located by referring to these holes. Drilling machines are used to produce most of these holes. They are also used in operations such as reaming, boring, countersinking, counterboring, and tapping.

在金属毛坯上加工圆孔是最常见的金属加工。很少有工件经过工厂没有被钻孔。后续的操作经常是参照这些孔而定位的。钻孔就是用来制造大多数这样的孔的一种机器。

There are several types of mechanisms used to control the speed of a drilling machine. The simplest arrangement utilizes（利用）a belt for transferring power from a four-step, five- step, or six-step V pulley(三角皮带轮) located on the motor to a similar puller attached to the drill press spindle. To increase power on some belt and pulley machines, a counter shaft drive is sometimes added. Another mechanism(原理)used is the variable-speed pulley, which makes it possible to change the machine’s speed without stopping it. In fact, the speed must only be changed while the machine is running. Pulleys of a variable(多变的)-speed drive are made of two parts having V-shaped sides.

有几种机构可以用来控制钻床的速度，最简单的装置就是皮带轮。它可以装在电机上一个四级、五级或六级皮带轮上将动力传到装在钻床主轴上的一个相似的皮带轮上。有时还增加一个中间轴驱动的目的是增加带和带轮机构的动力。另一个原理是应用变速皮带轮，它能在机器运转的时候改变机器的速度。事实上，机器的速度必须在机器运转的情况下改变。变速皮带轮是由两个V型面构成的。

Milling is a process of generating machined surfaces by progressively removing a predetermined amount of material from the workpiece. The process employs relative motion between a workpiece and a rotating cutter to generate the required surface. In some applications, the workpiece is held stationary while the rotating cutter is moved past it at a given feed rate.

铣削是一种逐步去除工件上预定的材料而渐渐形成机加表面的加工方法。它的工艺过程是通过工件和旋转的道具之间的相对运动等形成所需的表面。在一些应用中，工件是固定的，通过刀具在给定速度的运转下完成铣削。

Facing milling is done on both horizontal(水平的)and vertical(竖直的)milling machines. The milled surface resulting from the combined action of cutting edges located on the periphery and the face of the cutter is generally at right angles to the cutter axis(轴). The milled surface is flat , there being no relation to the contour of the teeth, expect when milling to a shoulder. Generally, face milling should be applied wherever and whenever possible.

端铣不仅可以在立式机床上加工，也可以在卧式铣床上加工。由装在外面的道具的刀刃及刀面的联合作用而产生的铣削表面常与刀轴成一直角，铣削表面是平的，与所使用的刀齿的轮廓无关，除非是铣削方向，一般在可能的场合可能的时间尽可能的使用端铣。

The way a grinding(刺耳的)wheel performs depends a good deal on how fast the wheel is turning and how fast the workpiece passes under it. If either the workpiece or the wheel moves too fast, the abrasive grains get very litter chance to do any cutting. In this case, the wheel gives

the impression of being hard. If the workpiece or the wheel moves too slowly, the abrasive grains cut for a longer time. Then the wheel seems to be soft.

一个砂轮的运转依靠的是轮子的转动速度和工件在轮子下面移动的速度。如果工件或者轮子速度太快，抛光粉就发挥不了作用。在这种情况下，轮子会表现的比较硬。如果工件或者轮子转动太慢，抛光粉就会工作较长时间，轮子就会变得比较柔软。

Offhand grinding is done by applying the grinding wheel manually to the work or by applying the work offhand to the grinding wheel. It is used to snag castings, grind wells, and sharpen tools. Offhand grinding cannot be done when close tolerances are required.

粗磨是利用砂轮手动或者自动进行工作，它是用来打磨的工具。如果尺寸公差要求很精密，粗磨就无法完成。

The electric-arc furnace is also used for producing special alloy steels which contain an appreciable amount of easily oxidized alloying elements such as chromium, tungsten, and molybdenum. It is also used when very low sulfur and phosphorus levels are necessary in some alloy steels. Special slag covers are used to lower sulfur and phosphorus levers and give protection against oxidation of the alloying element. Careful temperature control is also possible with this process.

电弧炉炼钢用于生产特殊合金钢，是一个包含数量可观的容易氧化的合金元素如铬、钨、钼。它也被使用于硫和磷含量很低的一些合金钢。一些特殊的炉渣覆盖在表面来降低硫和磷的含量并且保护合金不被氧化。控制温度也能做到对合金的保护。

Castings are identified by the type of mold or the force required to fill the mold. Molds are either permanent or expendable. The pattern of sand, shell, and plaster molds, however, can be used repeatedly for making new molds. Castings are made by pouring molten metal into a mold or die. As the metal cools, it takes the shape of the cavity. The basic casting methods are described below.

铸造方法是以模具的类型或填充模型所用的力来分类。模具可分为永久的和一次性的。砂型、薄壳和石膏模型都可以重复使用来制造新的模具。铸件是将熔融金属注入模子或钢模而制成的。当金属冷却后，它以型腔的形式出现。基本的铸造方法如下所述。

Continuous casting is a method where by a molten metal is continuously gravity fed from a ladle into an ingot mold of a desired shape which is open at both ends. As the metal “falls”through the mold, it takes its shape, and is rapidly cooled by a water spray. It is then cut to special lengths.

连续铸造是将熔融金属通过重力加料法加入一个两头都开着的钢锭模。随着金属在模具里流动，模具逐渐成形，并由水喷雾快速冷却，最后切成特定的长度。

Forging dates back to ancient times and, before the advent of modern production methods was associated with the “village blacksmith shop”. Forging is a production method where by heated metal stock is shaped to a desired form by compressive forces or by sharp hammer like blows.

锻造可追溯到古代，在现代生产方法还没出现以前的“乡村铁匠店”。锻造是一种在烧热的金属块上通过压缩或打击来得到需要的形状的生产方法。

Secondary production processes, in contrast with primary production processes, remove metal from a work piece in order to achieve a specified shape or configuration. The methods of metal removal may be classified into three categories namely, chip removal, chipless removal, and metal removal by heat. The most widely used of these methods is chip removal. It employs a hardened cutting tool to form the chip.

与粗加工工艺相比，精加工工艺从工件上切割是为了得到指定的形状和轮廓，这样金属切削的方法可分为三种：有屑切削、无屑切削和切削。在这些方法中，使用最广泛的是有屑切削。它使用了坚硬的工具从而形成金属屑。

The designer is not expected to be a machinist, but he is expected to be able to design various parts for a machine, structure, system, and so on, and therefore, be knowledgeable about the capabilities, type of cutting, and dimensional limitations of machine shop equipment.

The design is to formulate a plan for the satisfaction of human need. In the beginning the particular need to be satisfied may be quite well-defined. Here are two examples of well-defined needs.

设计是满足人类需求的一个明确的计划。一开始的时候，一些特殊需求是清晰可辨的。这儿有两个清晰可辨的需求的例子。

Revolving shovels dig the earth only during one part of the cycle, the rest of time being taken up by carrying the bucket to the dumping site and returning it back to the face. In a ditcher, all operations take place simultaneously. Despite a much higher efficiency of ditchers, their utilization construction is limited to straight line operation on uniform soils without large stones.

循环挖掘机只在循环的一部分期间挖掘土壤，其余时间则通过运转铲斗去堆放点和把铲斗返回到工作面。对开沟机而言，所有动作同时发生。尽管开沟机具有更高的效率，但它们的应用仅局限于在没有大石块的一致土壤中直线运行。

A revolving shovel is composed of the following main parts: front attachment (bucket, boom and stick for dipper and pull shovels, and bucket and boom for a drag line); turntable carrying a power plant, power train and hydraulic system; lower frame to take the weight of the turntable with mechanisms and operating equipment; travel unit with crawlers or wheels supporting the main frame.

旋转挖掘机由下面主要部分构成：前部附件（铲斗，用作支撑铲斗或拉铲的梁，用于索斗铲的斗和梁）；支撑动力装置的转盘，动力总成合液压系统；用于支撑转盘以及机构和操作设备重量的底架，用于支撑主底架的具有履带或轮子的行走单元。