Lesson 1 Basic Concepts in Mechanics
1、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
对运动、时间和作用力作出科学分析的分支称为力学。它由静力学和动力学两部分组成。
2、Our intuitive concept of force includes such ideas as place of application, direction,and magnitude
and these are called the characteristics of a force.
直观概念包括作用点、方向和大小。这些称为力的要素
3、Inertia is the property of mass that causes it to resist any effort to change its motion.
惯性是质量所具有的抵抗任何外力改变其本身运动状态的性质.
4、A particle is a body whose dimensions are so small that they may be neglected.
当一个物体的尺寸特别小，可以忽略不计时，该物体可以被称为质点。
5、Law 1 If all the forces acting on a particle are balanced, the particle will either remain at rest or will continue to move in a straight line at a uniform velocity.
第一定律如果作用在一个质点上的所有外力平衡，那么，这个质点保持原来的静止或者匀速直线运动状态不变。
Lesson 5 Shafts and Coupling s
1、Shafts are mounted in bearings and transmit power through such devices asgears), (pulleys), (cams) and (clutche)
.轴安装在轴承中，通过齿轮、皮带轮、凸轮和离合器等零件传递动力。'
2、Also, the allowable stress must contain a factor of safety which includes fatigue, since torsional and bending stress reversals occur.
因为扭矩和弯矩会产生交变应力，在许用应力中也应该有一个考虑疲劳现象的安全系数。
3、stress concentrations occur in shafts due to keyways, and the material removed to form the keyway further weakens the shaft.
轴上的键槽会引起应力集中，由于键槽的存在会使轴的横截面积减小，会进一步减弱轴的强度。
4、A coupling is a device for connecting the ends of adjacent shafts.
联轴器是用来把两个相邻轴端联结起来的装置。
5、In connecting shafts belonging to separate devices (such as an electric motor and a gearbox), precise aligning of the shafts is difficult and a flexible coupling is used.
在把属于不同的设备（例如一个电动机和一个变速箱）的轴联接起来的时候，要把这些轴精确地对准是比较困难的，此时可以采用弹性联轴器。
Lesson 13 Mechanism
1、A mechanism has been defined as “a combination of rigid or resistant bodies so formed and connected that they move upon each other with definite relative motion.”
机构被定义为：“是由刚体或者有承载能力的物体联接而形成的组合体，它们在运动时彼此之间应该具有确定的相对运动。”
2、There are three types of common mechanical devices that can be used as basic elements of a mechanism:Gear systems、Cam systems、Plane and Spatial Linkages
常用的基本机构有以下三种：齿轮机构凸轮机构平面和空间连杆机构
3、Cam systems, where a uniform motion of an input member is converted into a nonuniform
motion of the output member.
凸轮机构在这种机构中，输入件的等速连续地运动被转换成输出件的不等速运动。
4、The plane four-bar linkage, the plate cam and follower, and the slider-crank mechanism are familiar examples of planar mechanisms.
平面四连杆机构、平面凸轮和它的从动件、曲柄滑块机构是大家所熟悉的平面机构的例子。
5、Any linkage which contains a screw pair, for example, is a spatial mechanism, since the relative motion within a screw pair is helical.
任何含有螺旋副的连杆机构，由于其相对运动是螺旋线形的，因此是空间结构.
Lesson 17 Fundamentals of Mechanical Design
1、Mechanical design means the design of things and systems of a mechanical nature——machines, products, structures, devices, and instruments.
pulleys
机械设计是指机械装置和机械系统——机器、产品、结构、设备和仪器的设计。
2、The specifications define the cost, the number to be manufactured, the expected life, and the reliability.
这些设计要求将规定生产成本、产量、预期寿命、工作范围、操作温度和可靠性。
3、Both analysis and optimization require that we construct or devise abstract models of the system which will admit some form of mathematical analysis.
分析和优化都要求我们建立或者作出系统的抽象模型，以便对此进行数学分析。
4、Evaluation is a significant phase of the total design process. Evaluation is the final proof of a successful design, which usually involves the testing of a prototype in the laboratory.
评价是整个设计过程中的一个重要阶段。评价是对一个成功的设计的最后检验，通常包括样机的实验室试验。
5、Basically, there are only three means of communication available to us. These are the written, the oral, and the graphical forms.
人们基本上只有三种表达自己思想的方式，即文字材料、口头表述和绘图。
6、A technically competent person who lacks ability in any one of these forms is severely handicapped. If ability in all three forms is lacking, no one will ever know how competent that person is!
如果一个技术能力很强的人在上述三种表达方式中的某一种能力较差，他就会遇到很大的困难。如果上述三种能力都较差，那将永远没有人知道他是一个多么能干的人。
Lesson 19 Introduction to Machine Design
1、Machine design is the application of science and technology to devise new or improved products for the purpose of satisfying human needs.
机械设计是一门通过设计新产品或者改进老产品来满足人类需求的应用的技术科学。
2、However, in addition to being innovative, a design engineer must also have a solid background in the areas of mechanical drawing, kinematics, dynamics, materials engineering, strength of materials and manufacturing processes.（翻译句子）
设计工程师不仅在工作上要有创新性，还必须在机械制图、运动学、动力学、工程材料、材料力学和机械制造工艺等方面具有深厚的基础知识。
3、It is important to understand the fundamentals of engineering rather than memorize mere facts and equations.
掌握工程基础知识要比熟记一些数据和公式更为重要。
4、New designs generally have “bugs”or unforeseen problems which must be worked out before the superior characteristics of the new designs can be enjoyed.
新设计本身会有许多缺陷和未能预料的问题发生，只有当这些缺陷和问题被解决之后，才能体现出新产品的优越性。
5、It is essentially the responsibility of the design engineer to strive to fit machines to people.This is not easy task, since there is really no average person for which certain operating dimensions and proc
edures are optimum.
设计人员的基本职责是努力使机器来适应人们。这并不是一项容易的工作，因为实际上并不存在着一个对所有人来说都是最优的操作范围和操作过程。
6、Initially, the designer must communicate a preliminary design to get management approval. This is usually done by verbal discussions in conjunction with drawing layouts and written material.
在开始阶段，设计人员必须就初步设计同管理人员进行交流和磋商，并得到批准。这一般是通过口头讨论，草图和文字材料进行的。
Lesson 21 Material Selection
1、New materials often become available and there may be a decreasing availability of others. Concerns regarding environmental pollution, recycling and worker health and safety often impose new constraints.
新材料不断出现，而一些原有的材料的可以被利用的数量可能会减少。环境污染、材料的回收利用、工人的健康及安全等方面经常会对材料选择附加新的限制条件。
2、Therefore, it is imperative that design and manufacturing engineers exercise considerable care in selecting, specifying, and utilizing materials if they are to achieve satisfactory results at reasonable cost and still assure quality.
因此，为了能在合理的成本和确保质量的前提下获得满意的结果，设计工程师和制造工程师都必须认真仔细地选择、确定和使用材料。
3、There is much merit to the practice of one very successful company which requires that all prototypes be built with the same materials that will be used in production and, insofar as possible, with the same manufacturing techniques.
一个很有成就的公司在制造所有样机时，所选用的材料应该和其在生产中使用的材料相同，并尽可能使用同样的制造技术。这样做对公司是很有好处的。
4、While following the very best methods in material selection may not eliminate all product-liability claims, the use of proper procedures by designers and industries can greatly reduce their numbers.
尽量采用最好的材料选择办法也不能避免发生产品责任诉讼，设计人员和工业界按照适当的程序进行材料选择，可以大大减少诉讼的数量。
Lesson 23 Lathes
1、Lathes are machine tools designed primarily to do turning, facing, and boring.
车床主要是为了进行车外圆、车端面和镗孔等项工作而设计的机床。
2、The essential components of a lathe are the bed, headstock assembly, tailstock assembly, carriage assembly, and the leadscrew and feed rod.
车床的基本部件有：床身、主轴箱组件、尾架组件、溜板组件、丝杠和光杠。
3、Any inaccuracy in them usually means that the accuracy of the entire lathe is destroyed.
导轨上的任何误差常常意味着整个机床的精度遭到破坏。
4、Essentially, it consists of a hollow spindle, mounted in accurate bearings, and a set of transmission gears - similar to a truck transmission - through which the spindle can be rotated at a number of speeds .
它基本上由一个安装在精密轴承中的空心主轴和一系列变速齿轮——类似于卡车变速箱——所组成。通过变速齿轮，主轴可以在许多种转速下旋转。
5、The size of this hole is an important dimension of a lathe because it determines the maximum size of bar stock that can be machined when the material must be fed through spindle.
主轴孔的大小是车床的一个重要尺寸，因为当工件必须通过主轴孔供料时，它确定了能够加工的棒料毛坯的最大尺寸。
6、The size of a lathe is designated by two dimensions. The first is known as the swing. T his is the maximum diameter of work that can be rotated on a lathe.
车床的规格用两个尺寸表示。第一个称为车床床面上最大加工直径。这是在车床上能够旋转的工件的最大直径。
7、The second size dimension is the maximum distance between centers.
第二个规格尺寸是两顶尖之间的最大距离。
8、Although engine lathes are versatile and very useful, because of the time required for changing and setting tools and for making measurements on the workpiece, they are not suitable for quantity production.
虽然普通车床有很多用途，是很有用的机床，但是更换和调整刀具以及测量工件花费很多时间，所以它们不适合在大量生产中应用。
Lesson 27 Metal-Cutting Process
1、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
其特点是工件在加工前具有足够大的尺寸，可以将工件最终的几何形状包容在里面。不需要的材料以切屑、颗粒等形式被去除掉。
2、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
然而，由于金属成形加工的模具成本和设备成本仍然很高，因此尽管金属切削加工的材料消耗较高，在许多情况下，他们仍然是最经济的
3、The final geometry is thus determined from the geometry of the tool and the pattern of motions of t
he tool and the workpiece. The basic process is mechanical: actually, a shearing action combined with fracture.
因此，刀具的几何形状和刀具与工件的运动方式决定了工件的最终形状。这个基本过程是机械过程：实际上是一个剪切与断裂相结合的过程。
4、Examples of processes in this group are turning, drilling, reaming, milling, shaping, planning, broaching, grinding, honing, and lapping.
属于此类加工方法的例子有车削、钻削、铰孔、铣削、牛头刨削、龙门刨削、拉削、磨削、珩磨和研磨。
5、These motions are defined as the primary motion, which mainly determines the cutting speed, and the feed motion, which provides the cutting zone with new material
一种定义为主运动（决定切削速度），另一种定义为进给运动（向切削区提供新的加工材料）
6、Basic machining parameters in turning:
Cutting Speed、Feed、Depth of cut(Back Engagement)、Chip Thickness、Chip Width、Area of Cut
车削加工的基本参数
车削速度、进给量、切削深度（吃刀深度）、切屑厚度、切屑宽度、切削面积
7、A plane containing the directions of the primary motion and the feed motion is defined as the working plane (概念)
包含主运动方向和进给运动方向的平面被定义为工作平面
Lesson 35 Nontraditional Manufacturing Processes
1、Through the centuries, both the tools and the energy sources to power these tools have evolved to meet the increasing sophistication and complexity of mankind’s ideas.
许多世纪以来，工具和为工具提供动力能源的种类都在不断地发展，以满足人类日益完善和越来越复杂的想法。
2、In an effort to meet the manufacturing challenges created by these materials, tools have now evolved to include materials, such as alloy steel, carbide, diamond, and ceramics.
为了迎接这些材料给制造业带来的挑战，工具材料已经发展到包括合金钢、硬质合金、金钢石和陶瓷。
3、However as the powers of water, wind, steam, and electricity were harnessed, mankind was able to further extend manufacturing capabilities with new machines, greater accuracy, and faster machining rates.
随后，水力、风力、蒸汽和电力得到了利用，人类能够通过采用新型机器、更高的精度和更快的加工速度来进一步提高制造能力。
4、The result has been the introduction of new manufacturing processes used for material removal, forming, and joining, known today as nontraditional manufacturing processes
这样做的结果是产生了用来去除材料、成型、联结的新型制造工艺。这些工艺目前被称为特种制造工艺。
5、Material removal can now be accomplished with electrochemical reactions, high-temperature plasmas, and high-velocity jets of liquids and abrasives.
现在材料的去除可以利用电化学反应、高温等离子、高速液体和磨料射流。
6、Materials that in the past have been extremely difficult to form, are now formed with magnetic fields, explosives, and the shock wave s from powerful electric sparks.Material-joining capabilities hav
e been expanded with the use of high-frequency sound waves and beams of electrons
过去非常难进行成型加工的材料，现在可以利用大功率的电火花所产生的磁场，爆炸和冲击波进行成型加工。.采用高频声波和电子束可以使材料联接能力有很大的提高。
7、The reason there are such a large number of nontraditional processes is the same reason there are such a large number of conventional processes; each process has its own characteristic attributes and limitations, hence no one process is best for all manufacturing situations.
这么多种特种加工工艺存在的原因与许多种常规加工工艺存在的原因是一样的。每一种工艺都有它自己的特点和局限性。因而不存在一种对任何制造环境来说都是最好的工艺方法。
Lesson 43 Quality and Inspection

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