机械工程专业英语文本施平10

Metal-Cutting ProcessMetal-cutting processes are extensively used in the manufacturing industry.They are characterized by the fact that the size of the original workpiece is sufficiently large that the final geometry can be circumscribed by it, and that the unwanted material is removed as chips, particles, and so on. The chips are a necessary means to obtain the desired tolerances, and surfaces. The amount of scrap may vary from a few percent to 70%--80% of the volume of the original work material.Owing to the rather poor material utilization of the metal-cutting processes, the anticipated scarcity of materials and energy, and increasing costs, the development in the last decade has been directed toward an increasing application of metal-forming processes. However, die costs and the capital cost of machines remain rather high; consequently, metal-cutting processes are, in many cases, the most economical, in spite of the high material waste, which only has value as scrap. Therefore, it must be expected that the material removal processes will for the next few years maintain their important position in manufacturing. Furthermore, the development of automated production systems has progressed more rapidly for metal-cutting processes than for metal-forming processes.In metal-cutting processes, the imprinting of information is carried out by a rigid medium of transfer, which is moved relative to the workpiece, and the mechanical energy is supplied through the tool. The final geometry is thus determined from the geometry of the tool and the pattern of motions of the tool and the workpiece. The basic process is mechanical: actually, a shearing action combined with fracture.As mentioned previously, the unwanted material in metal-cutting processes is removed by a rigid cutting tool, so that the desired geometry, tolerances, and surface finish are obtained. Examples of processes in this group are turning, drilling, reaming, milling, shaping, planning, broaching, grinding, honing, and lapping.Most of the cutting or machining processes are based on a two-dimensional surface creation, which means that two relative motions are necessary between the cutting tool and the work material. These motions are defined as the primary motion, which h mainly determines the cutting speed, and the feed motion, which provides the cutting zone with new material.In turning the primary motion is provided by the rotation of the workpiece, and in planning it is provided by the translation of the table; in turning the feed motion is a continuous translation of the tool, and in planning it is an intermittent translation of the tool.《机械工程专业英语》哈尔滨工业大学出版社施平金属切削加工金属切削加工在制造业中等到了广泛的应用。

Lesson11、the branch of scientific analysis, which deals with motions, time, and forces, is called mechanics and is made up of two parts, statics and dynamics. Statics deals with the analysis of stationary systems, i.e., those in which time is not a factor, and dynamics deals with systems, which change with time.对运动时间和作用力作出科学分析的分支成为力学。

他由静力学和动力学两部分组成。

静力学对静止系统进行分析，即在其中不考虑时间这个引述，动力学对事件而变化的系统进行分析。

2、Any two such forces acting on a body constitute a couple. The arm of the couple is the perpendicular distance between their lines of action, and the plane of the couple is the plane containing the two lines of action.作用在一个刚体上的两个这样的的里构成一个力偶。

力偶臂是这两个条作用线之间的垂直距离，力偶面是包含着两条作用线的平面。

3、Mechanics deal with two kinds of quantities: scalars and vectors. Scalar quantities are those with which a magnitude alone is associated. Examples of scalar quantities in mechanics are time, volume, density, speed, energy, and mass. Vector quantities, on the other hand, possess direction as well as magnitude. Examples of vectors are displacement, velocity, acceleration, force, moment, and momentum.力学涉及两种类型的量，标量和矢量。

第10 次课的教学整体安排2.教学内容与讨论、思考题、作业部分可合二为一。

14 Lathes车床Lathes are widely used in industry to produce all kind of machined parts. Some are general-purpose(通用的) machines, and others are used to perform highly specialized operations.Engine Lathes普通车床Engine lathes, of course are general-purpose machines used in production and maintenance shops all over the world. Sizes range from small bench models to huge heavy-duty(重型的) piece of equipment. Many of the larger lathes come equipped with attachments not commonly found in the ordinary shop, such as automatic stops for the carriage.Tracer or Duplicating Lathes仿形/靠模车床The tracer or duplicating lathe is designed to produce irregularly shaped parts automatically. The basic operation of this lathe is as follows: A template(模板、模型) of either a flat or three-dimensional shape is placed in a holder. A guider or pointer(仿形指) then moves along this shape and its movement controls that of the cutting tool. The duplication may include a square or tapered(锥形的) shoulder(台肩), grooves, tapers(锥体), and contours. Works such as motor shafts, spindles, pistons, rods, car axles, turbine shafts, and a variety of other objects can be turned using this type of lathe.Turret Lathes 转塔车床A Turret lathe is basically similar to an engine lathe except that the conventional tool post is replaced with a hexagonal turret, which can be rotated around a vertical axis as required. Appropriate tools are mounted on the sixsides of the turret. The length of each tool is so adjusted that by simply indexing(转动) the turret, any tool can be brought in exactly the desired operating condition. Those cutting tools can, therefore be employed successively(依次地) without the need for dismounting the tool and mounting a new one each time, as the case with conventional engine lathe. This result in an appreciate saving in the time required for setting up the tools. Also, on a turret lathe a skilled machinist is required only initially to set up the tools. (对刀) A laborer with limited training can operate the turret lathe thereafter and produce parts identical to those that can be manufactured when a highly skilled machinist operates the lathe.Automatic Screw Machine自动切丝机Screw machine are similar in construction to turret lathe, except that their heads are designed to hold and feed long bars of stock. Otherwise, there is little difference between them. Both are designed for multiple tooling, and both have adaptations for identical work. Originally, the turret lathe was designed as a chucking lathe for machining small castings, forgings, and irregularly shaped work piece. The first screw machines were designed to feed bar stock and wire used in making small screw parts. Today, however, the turret lathe is frequently used with a collet attachment, and the automatic screw machine can be equipped with a chuck to hold castings.The single-spindle automatic screw machine, as its name implies, machines work on only one bar of stock at a time. A bar 16 to 20mfeet long is fed through the headstock spindle and is held firmly by a collet. The machining operations are done by cutting tools mounted on the turret and on the cross slide. When the machine is in operation, the spindle and the stock are rotated atselected speeds for different operations. If required, rapid reversal of the spindle is also possible.In the single-spindle automatic screw machine, a specific length of stock is automatically fed through the spindle to a machining area. At this point, the turret and the cross slide move into position and automatically perform whatever operation are required. After the machined piece is cut off, stock is again fed into the machining area and the entire cycle is repeated.Multiple-spindle automatic screw machines have four to eight spindles located around a spindle carrier. Long bar of stock, supported on the rear of the machine, pass through these hollow spindles and are gripped by collets. With the single-spindle machine, the turret indexes around the spindle. When one tool on the turret is working, the others are not. With a multiple-spindle machine, however, the spindle itself indexes. Thus the bars of stock are carried to the various end-working and side-working tools. Each tool operates in only position, but all tools operate simultaneously. Therefore, four to eight work pieces can be machined at the same time.Vertical Turret Lathes立式转塔车床A vertical turret lathe is basically a turret lathe that has been stood on its headstock end. It is designed to perform a variety of turning operations. It consists of a turret, a revolving table, and a slide head with a square turret for holding additional tools. Operations performed by any of the tools mounted on the turret or side head can be controlled through the use of stops.Machining Center(MC加工中心)Many of today’s more sophisticated lathes are called machining centers since they are capable of performing, in addition to the normal turning operations,certain milling and drilling operations. Basically, a machining center can be thought of as being a combination turret lathe and milling machine. Additional features are sometimes included by manufacturers to increase the versatility of their machines.(FMS F lexible M anufacturing S ystem柔性制造系统)(HSC H igh S peed C utting 高速切削)。

Spur GearsGears , defined as toothed members transmitting rotary motion from one shaft to another , are among the oldest devices and inventions of man . In about 2600 B.C. , the Chinese are known to have used a chariot incorporating a complex series of gears . Aristotle , in the fourth century B.C. , wrote of gears as if they were commonplace . In the fifteenth century A.D. , Leonardo da Vinci designed a multitude of devices incorporating many kinds of gears .齿轮，在最古老的设备和发明人中，被定义为通过轮齿将旋转运动从一根轴传递到另一根轴，大约在公元前2600年，中国人就知道用战车组成一系列复杂的齿轮系。

西元前四世纪，亚里士多德记述了齿轮就好像是他们司空见惯的一样。

在十五世纪，达芬奇设计了大量的包含各种各样齿轮的设备。

Among the various means of mechanical power transmission (including primarily gears , belts , and chains ) , gears are generally the most rugged and durable . Their power transmission efficiency is as high as 98 percent . On the other hand , gears are usually more costly than chains and belts . As would be expected , gear manufacturing costs increase sharply with increased precision -- as required for the combination of high speeds and heavy loads , and for low noise levels . ( Standard tolerances for various degrees of manufacturing precision have been established by the AGMA , American Gear Manufacturers Association. )在众多的机械传动方式中（包括齿轮传动，带传动，链传动），一般来说，齿轮是最经久耐用的，它的能量传递效率高达98%。