机械专业英文求职信

第一篇：机械专业英文求职信

机械专业英文翻译

Design of machine and machine elements Machine design Machine design is the art of planning or devising new or improved machines to accomplish specific purposes. In general, a machine will consist of a combination of several different mechanical elements properly designed and arranged to work together, as a whole. During the initial planning of a m

The objective is to produce a machine which is not only sufficiently rugged to function properly for a reasonable life, but is at the same time cheap enough to be economically feasible.

The engineer in charge of the design of a machine should not only have adequate technical training, but must be a man of sound judgment and wide experience, qualities which are usually acquired only after considerable time has been spent in actual professional work. Design of machine elements

The principles of design are, of course, universal. The same theory or equations may be applied to a very small part, as in an instrument, or, to a larger but similar part used in a piece of heavy equipment. In no ease, however, should mathematical calculations be looked upon as absolute and final. They are all subject to the accuracy of the various assumptions, which must necessarily be made in engineering work. Sometimes only a portion of the total number of parts in a machine are designed on the basis of analytic calculations. The form and size of the remaining parts are designed on the basis of analytic calculations. On the other hand, if the machine is very expensive, or if weight is a factor, as in airplanes, design computations may then be made for almost all the parts.

The purpose of the design calculations is, of course, to attempt to predict the stress or deformation in the part in order that it may sagely carry the loads, which will be imposed on it, and that it may last for the expected life of the machine. All calculations are, of course, dependent on the physical properties of the construction materials as determined by laboratory tests. A rational method of design attempts to take the results of relatively simple and fundamental tests such as tension, compression, torsion, and fatigue and apply them to all the complicated and involved situations encountered in present-day machinery.

In addition, it has been amply proved that such details as surface condition, fillets, notches, manufacturing tolerances, and heat treatment have a market effect on the strength and useful life of a machine part. The design and drafting departments must specify completely all such particulars, must specify completely all such particulars, and thus exercise the necessary close control over the finished product.

As mentioned above, machine design is a vast field of engineering technology. As such, it begins with the conception of an idea and follows through the various phases of design analysis, manufacturing, marketing and consumerism. The following is a list of the major areas of consideration in the general field of machine design: ① Initial design conception;

② Strength analysis; ③ Materials selection; ④ Appearance; ⑤ Manufacturing; ⑥ Safety; ⑦ Environment effects; ⑨ Reliability and life;

Strength is a measure of the ability to resist, without fails, forces which cause stresses and strains. The forces may be; ① Gradually applied; ② Suddenly applied; 2

③ Applied under impact; ④ Applied with continuous direction reversals; ⑤ Applied at low or elevated temperatures.

If a critical part of a machine fails, the whole machine must be shut down until a repair is made. Thus, when designing a new machine, it is extremely important that critical parts be made strong enough to prevent failure. The designer should determine as precisely as possible the nature, magnitude, direction and point of application of all forces. Machine design is mot, however, an exact science and it is, therefore, rarely possible to determine exactly all the applied forces. In addition, different samples of a specified material will exhibit somewhat different abilities to resist loads, temperatures and other environment conditions. In spite of this, design calculations based on appropriate assumptions are invaluable in the proper design of machine.

Moreover, it is absolutely essential that a design engineer knows how and why parts fail so that reliable machines which require minimum maintenance can be designed. Sometimes, a failure can be serious, such as when a tire blows out on an automobile traveling at high speeds. On the other hand, a failure may be no more than a nuisance. An example is the loosening of the radiator hose in the automobile cooling system. The consequence of this latter failure is usually the loss of some radiator coolant, a condition which is readily detected and corrected.

The type of load a part absorbs is just as significant as the magnitude. Generally speaking, dynamic loads with direction reversals cause greater difficulties than static loads and, therefore, fatigue strength must be considered. Another concern is whether the material is ductile or brittle. For example, brittle materials are considered to be unacceptable where fatigue is involved.

In general, the design engineer must consider all possible modes of failure, which include the following: ① Stress; ② Deformation; 3

③ Wear; ④ Corrosion; ⑤ Vibration; ⑥ Environmental damage; ⑦ Loosening of fastening devices.

The part sizes and shapes selected must also take into account many dimensional factors which produce external load effects such as geometric discontinuities, residual stresses due to forming of desired contours, and the application of interference fit joint.

Selected from” design of machine elements”, 6th edition, m. f. sports, prentice-hall, inc., 1985 and “machine design”, Anthony Esposito, charles e., Merrill publishing company, 1975.

Quality assurance and control

Product quality is of paramount importance in manufacturing. If quality is allowed deteriorate, then a manufacturer will soon find sales dropping off followed by a possible business failure. Customers expect quality in the products they buy, and if a manufacturer expects to establish and maintain a name in the business, quality control and assurance functions must be established and maintained before, throughout, and after the production process. Generally speaking, quality assurance encompasses all activities aimed at maintaining quality, including quality control. Quality assurance can be divided into three major areas. These include the following: ①Source and receiving inspection before manufacturing; ②In-process quality control during manufacturing; ③Quality assurance after manufacturing.

Quality control after manufacture includes warranties and product service extended to the users of the product.

Source and receiving inspection before manufacturing

Quality assurance often begins ling before any actual manufacturing takes place. This may be done through source inspections conducted at the plants that

supply materials, discrete parts, or subassemblies to manufacturer. The manufacturer’s source inspector travels to the supplier factory and inspects raw material or premanufactured parts and assemblies. Source inspections present an opportunity for the manufacturer to sort out and reject raw materials or parts before they are shipped to the manufacturer’s production facility.

The responsibility of the source inspector is to check materials and parts against design specifications and to reject the item if specifications are not met. Source inspections may include many of the same inspections that will be used during production. Included in these are: ①Visual inspection; ②Metallurgical testing; ③Dimensional inspection; ④Destructive and nondestructive inspection; ⑤Performance inspection. Visual inspections

Visual inspections examine a product or material for such specifications as color, texture, surface finish, or overall appearance of an assembly to determine if there are any obvious deletions of major parts or hardware.

Metallurgical testing

Metallurgical testing is often an important part of source inspection, especially if the primary raw material for manufacturing is stock metal such as bar stock or structural materials. Metals testing can involve all the major types of inspections including visual, chemical, spectrographic, and mechanical, which include hardness, tensile, shear, compression, and spectr5ographic analysis for alloy content. Metallurgical testing can be either destructive or nondestructive.

Dimensional inspection

Few areas of quality control are as important in manufactured products as dimensional requirements. Dimensions are as important in source inspection as they are in the manufacturing process. This is especially critical if the source supplies parts for an assembly. Dimensions are inspected at the source factory

using standard measuring tools plus special fit, form, and function gages that may required. Meeting dimensional specifications is critical to interchangeability of manufactured parts and to the successful assembly of many parts into complex assemblies such as autos, ships, aircraft, and other multipart products.

Destructive and nondestructive inspection

In some cases it may be necessary for the source inspections to call for destructive or nondestructive tests on raw materials or p0arts and assemblies. This is particularly true when large amounts of stock raw materials are involved. For example it may be necessary to inspect castings for flaws by radiographic, magnetic particle, or dye penetrant techniques before they are shipped to the manufacturer for final machining. Specifications calling for burn-in time for electronics or endurance run tests for mechanical components are further examples of nondestructive tests.

It is sometimes necessary to test material and parts to destruction, but because of the costs and time involved destructive testing is avoided whenever possible. Examples include pressure tests to determine if safety factors are adequate in the design. Destructive tests are probably more frequent in the testing of prototype designs than in routine inspection of raw material or parts. Once design specifications are known to be met in regard to the strength of materials, it is often not necessary to test further parts to destruction unless they are genuinely suspect.

Performance inspection

Performance inspections involve checking the function of assemblies, especially those of complex mechanical systems, prior to installation in other products. Examples include electronic equipment subcomponents, aircraft and auto engines, pumps, valves, and other mechanical systems requiring performance evaluation prior to their shipment and final installation. Selected form “modern materials and manufacturing process”

Electro-hydraulic drum brakes Application

The YWW series electro-hydraulic brake is a normally closed brake, suitable for horizontal mounting. It is mainly used in portal cranes, bucket stacker/reclaimers’slewing mechanism. The YKW series electro-hydraulic brake is a normally opened brake, suitable for horizontal mounting, employing a thruster as actuator. with the foot controlling switch the operator can release or close the brake. It is mainly used for deceleration braking of portal cranes’slewing mechanism. In a non-operating state the machinery can be braked by a manual close device. The RKW series brake is a normally opened brake, which is operated by foot driven hydraulic pump, suitable for horizontal mounting. Mainly used in the slewing mechanism of middle and small portal cranes. When needed, the brake is activated by a manual closed device. Main design features Interlocking shoes balancing devices (patented technology) constantly equalizes the clearance of brake shoes on both sides and made adjustment unnecessary, thus avoiding one side of the brake lining sticking to the brake wheel. The brake is equipped with a shoed autoaligning device. Main hinge points are equipped with self-lubricating bearing, making high efficiency of transmission, long service life. Lubricating is unnecessary during operation. Adjustable bracket ensure the brake works well. The brake spring is arranged inside a square tube and a surveyor’s rod is placed on one side. It is easy to read braking torque value and avoid measuring and computing. Brake lining is of card whole-piece shaping structure, easy to replace. Brake linings of various materials such as half-metal (non-asbestos) hard and half-hard, soft (including asbestos) substance are available for customers to choose.

All adopt the company’s new types of thruster as corollary equipment which work accurately and have long life.

Hydraulic Power Transmission The Two Types Of Power Transmission

In hydraulic power transmission the apparatus (pump) used for conversion of the mechanical (or electrical,thermal) energy to hydraulic energy is arranged on the input of the kinematic chain ,and the apparatus (motor) used for conversion of the hydraulic energy to mechanical energy is arranged on the output (fig.2-1)

The theoretical design of the energy converters depends on the component of the bernouilli equation to be used for hydraulic power transmission.

In systerms where, mainly, hydrostatic pressure is utilized, displacement (hydrostatic) pumps and motors are used, while in those where the hydrodynamic pressure is utilized is utilized gor power transmission hydrodynamic energy converters (e.g. centrifugal pumps) are used.

The specific characteristic of the energy converters is the weight required for transmission of unit power. It can be demonstrated that the use of hydrostatic energy converters for the low and medium powers, and of hydrodynamic energy converters of high power are more favorite (fig.2-2). This is the main reason why hydrostatic energy converters are used in industrial apparatus. transformation of the energy in hydraulic transmission. 1. 2. 3. 4. 5. 6. 7. driving motor (electric, diesel engine); mechanical energy; pump;

hydraulic energy;

hydraulic motor; mechanical energy;

load variation of the mass per unit power in hydrostatic and hydrodynamic energy converters

1、hydrostatic; 2.hydrodynamic Only displacement energy converters are dealt with in the following. The

elements performing converters provide one or several size. Expansion of the working chambers in a pump is produced by the external energy admitted, and in the motor by the hydraulic energy. Inflow of the fluid occurs during expansion of the working chamber, while the outflow (displacement) is realized during contraction. Such devices are usually called displacement energy converters.

The Hydrostatic Power

In order to have a fluid of volume V1 flowing in a vessel at pressure work spent on compression W1 and transfer of the process, let us imagine a piston mechanism (fig.2-3(a)) which may be connected with the aid of valves Z0 and Z1 to the external medium under pressure P0 and reservoir of pressure p1.in the upper position of the piston (x=x0) with Z0 open the cylinder chamber is filled with fluid of volume V0 and pressure P0. now shut the value Z0 and start the piston moving downwards. If Z1 is shut the fluid volume in position X=X1 of the piston decreases from V0 to V1, while the pressure rises to P1. the external work required for actuation of the piston (assuming isothermal change) is W1=-∫0x0(P-P0)Adx=-∫v1v0(P-P0)dv

Select from Hydraulic Power Transmission

机器和机器零件的设计

机器设计

机器设计为了特定的目的而发明或改进机器的一种艺术。一般来讲，机器时有多种不同的合理设计并有序装配在一起的部件构成的，在最初的机器设计阶段，必须基本明确负载、元件的运动情况、工程材料的合理使用性能。负责新机器的设计最初的最重要的是经济性考虑。一般来说，选择总成本最低的设计方案，不仅要考虑设计、制造、销售、安装的成本。还要考虑服务的费用，机械要保证必要的安全性能和美观的外形。

制造机器的目标不仅要追求保证只用功能的合理寿命，还要保证足够便宜以同时保证其经济的可行性。负责设计机器的工程师，不仅要经过专业的培训，而且必须是一个准确判断而又有丰富经验的人，具有一种有足够时间从事专门的实际工作的素质。

机器零件的设计

相同的理论或方程可应用在一个一起的非常小的零件上，也可用在一个复杂的设备的大型相似件上，既然如此，毫无疑问，数学计算是绝对的和最终的。他们都符合不同的设想，这必须由工程量决定。有时，一台机器的零件全部计算仅仅是设计的一部分。零件的结构和尺寸通常根据实际考虑。另一方面，如果机器和昂贵，或者质量很重要，例如飞机，那麽每一个零件都要设计计算。

当然，设计计算的目的是试图预测零件的应力和变形，以保证其安全的带动负载，这是必要的，并且其也许影响到机器的最终寿命。当然，所有的计算依赖于这些结构材料通过试验测定的物理性能。国际上的设计方法试图通过从一些相对简单的而基本的实验中得到一些结果，这些试验，例如结构复杂的及现代机械设计到的电压、转矩和疲劳强度。

另外，可以充分证明，一些细节，如表面粗糙度、圆角、开槽、制造公差和热处理都对机械零件的强度及使用寿命有影响。设计和构建布局要完全详细地说明每一个细节，并且对最终产品进行必要的测试。

综上所述，机械设计是一个非常宽的工程技术领域。例如，从设计理念到设计分析的每一个阶段，制造，市场，销售。以下是机械设计的一般领域应考虑的主要方面的清单：

①最初的设计理念

②受力分析

③材料的选择

④外形

⑤制造

⑥安全性

⑦环境影响

⑧可靠性及寿命

在没有破坏的情况下，强度是抵抗引起应力和应变的一种量度。这些力可能是：

①渐变力

②瞬时力

③冲击力

④不断变化的力

⑤温差

如果一个机器的关键件损坏，整个机器必须关闭，直到修理好为止。设计一台新机器时，关键件具有足够的抵抗破坏的能力是非常重要的。设计者应尽可能准确地确定所有的性质、大小、方向及作用点。机器设计不是这样，但精确的科学是这样，因此很难准确地确定所有力。另外，一种特殊材料的不同样本会显现出不同的性能，像抗负载、温度和其他外部条件。尽管如此，在机械设计中给予合理综合的设计计算是非常有用的。

此外，显而易见的是一个知道零件是如何和为什麽破坏的设计师可以设计出需要很少维修的可靠机器。有时，一次失败是严重的，例如高速行驶的汽车的轮胎爆裂。另一方面，失败未必是麻烦。例如，汽车的冷却系统的散热器皮带管松开。这种破坏的后果通常是损失一些散热片，可以探测并改正过来。零件负载类型是一个重要的标志。一般而言，变化的动负载比静负载会引起更大的差异。因此，疲劳强度必须符合。另一个关心的方面是这种材料是否直或易碎。例如有疲劳破坏的地方不易使用易碎的材料。一般的，设计师要靠考虑所有破坏情况，其包括以下方面：

①应力

②应变

③外形

④腐蚀

⑤震动

⑥外部环境破坏

⑦紧固件的松脱

零件的尺寸和外形的选择也有很多因素。外部负荷的影响，如几何间断，由于轮廓而产生的残余应力和组合件干涉。

质量保证与控制

产品质量是生产中最重要的。如果放任质量恶化下去，生产者会很快发现销售量锐减，可能从而会导致产业的失败。用户期望他们买的产品质量性能好，而且如果制造商想建立并维持其信誉，必须在产品制造前制造过程中及制造过程后进行质量控制和质量保证。一般来说，质量保证包括所有的活动，其包括质量建立和质量控制。质量保证可以被分为三个主要领域，他们如下所述： ①制造之前的原材料的检查 ②在制造加工过程中的质量控制 ③制造之后的质量保证

生产制造后的质量控制包括保证书和面对产品用户的服务。 生产制造之前的原材料检验

质量保证常常在实际生产制造之前就开始了。这些都是生产者在供应原材料、散件或配件的车间里进行检验。生产制造公司的原材料检验员到供应厂并且检查原材料及于制造的另配件。原材料检验为生产者提供了一次机会，那就是在原料及散件被运到生产车间之前先进行挑选淘汰。原料检察员的责任是去检查原料和零件是否达到设计规格并且淘汰那些未达到特殊指标的原料。原料检验有很多于检查产品相同的检验。其如下所述： ①目测 ②冶金测试 ③尺寸测试

④损伤检验 ⑤性能检验 目测

目测检验一种产品或原料的某些特征，如颜色、纹理、表面光洁度或部件的总体外观，从而判断其是否具有明显的缺损。 冶金测试

冶金测试常常是原料间严厉的一个很重要的部分，尤其是像棒料、建筑材料毛坯一些原材料。金属测试包含所有主要的检验类型，其中有目测，化学检验，光谱检验和机械性能检验，其包括硬度、伸缩性能、剪切性能、压缩性能和合成 12

成分的光谱分析。冶金测试既可用于成品件也可用于预制件。 尺寸检验

质量控制的一些领域是重要的生产件的要求尺寸。尺寸在检验过程中，像其在生产过程中一样重要。如果这些零件是为总成供应的，那尺寸尤其严格。一些尺寸在生产车间用标准测量工具进行检验，像特种接头、造型和需求的功能标准度量。符合尺寸规格对所制造多部件的互换性和对多部件成功组装成复杂的装置，如汽车、轮船、飞机和其他多部件产品都地极其重要的。 损伤检验

在一些情况下，对原材料或零部件采取损伤测试的原始测验是很必要的。特别是涉及到大批的原材料时。例如，在被运到生产车间作最终机器之前，对铸件进行X-射线、电磁离子、染色渗透剂技术的探伤是很必要的，又对机器总成的电子或持久运作测试而确定的规格，是无损测试的又一例证。有时，对材料及零件的测试是很必要的，但由于无损测试的花费和成本及时间不是任何时候都允许的。

例如，有压力测试决定在设计中其是否安全。损伤测试经常用于设计样机的测试，而不是原材料或零件的常规检验。一旦设计达到了所希望的材料强度，通常对零件做进一步的损伤测试是不必要的，除非他们确实存在疑点。

性能测试

性能测试在零部件被其他产品被安装之前，检查部件的功能，尤其是那些机械构造复杂的部件。例如电子设备零件，飞机和汽车发动机，泵、阀及其他需要在装运和最后安装前进行性能测验的机械系统。

选自《现代材料和制造工艺》

汽车起重机的不同类型

根据汽车吊的使用情况，像：工作的范围，工作的自然情况。他们的构造装备体现着不同的理念。

1、 工作范围(不同的设计)

当起重机工作在一个小范围内(仓库，码头，戏台等)告诉是没有必要的。根据这种应用，我们的装置最高速为35km/h。

驱动装置布置在后面，集成了车辆和起重机的控制，这种类型称为：单驱起重机。当起重机在大场地内工作时，有几个较远的工作点，高速轴就是必要的了。随之而来的，布置在车辆后端的单驱动是不可能的。由于这个原因，提供两个驱动是必要的，相对的允许像传统卡车那样驱动车辆。这种类型的起重机，在构造上必须装备一个特殊的变速箱，对起重机允许像传统车辆那样的前进和后退。我们这种类型的起重机装备了一个特殊的变速箱，可以提供一个前进速度和一个后退速度，一般其最大运输速度为：55/60km/h，这种类型称为双驱起重机。

2、 地面情况

当起重机操作困难时，在平整的路面上(体育场，码头，仓库等)起构造是传统概念的单驱动的运输工具。

如果起重机离开路面移动到恶劣路况下(脏且沙软的路面)不平的，其构造根据“全工况路面”的限定标准而建立，其要求实现：

双驱甚至是三驱;两种速度范围，有一个特别慢的值;不同驱动轴的转换系统;轴端的特殊轴承;特殊的制动;提供低压的大尺寸的轮胎，在软地面上运转;独立的大车轮;悬空的地面监视和清晰的构造是非常重要的;安装及驾驶服务

所有的主要点是绝对必要的对于在无路的情况下的各种类型的车辆，有一个良好的运行。

当然起重机不得不在各种路况下工作，为此其装备了双驱。

(附图见英文资料)

液力传动

动力传动的两种类型

在液力传动中，用来将机械能(电能、化学能)转化成液力能的装置(泵)被布置在传动链的输入端，而用来将液力能转化成机械能的装置(马达)被布置在输出端。(图2-1)

这种能量转化的理论上的设计依据是液力传动的各部分的伯努里方程。

在系统中，流体静压力主要用来替代泵和马达，而在某些方面，流体动力是作为液力能转化后的力传动而被利用的(如离心泵)这种能量转换的特征取决于单位力的传动。他能说明这种微小力的液体静压力能转换和高压力的液体动力能转换更受人们的欢迎。(图2-2)者是液力转换被应用于工业器械的主要原因。 液力传动的能量转换

1、原动机(电机、内燃机)

2、机械能

3、泵

4、液力能

5、液压马达

6、机械能

7、负载 在流体静力能和流体动力能中单位里的质量变化

替代能量转换仅应用以下几方面，在液体静压力转换中相关的替代执行元件提供一个或数个工作室，他们恒定或尺寸可变。

泵的工作室在外部能量进入时伸长，马达是靠液力能，工作是伸长时液体流入，而收缩时实现流体流出。这些装置通常被称为能量转换装置。液体充满一个体积为V1的容器，在压力P1下所作的功W是压缩功W1和改变液体的功W2组成的。

为了分析这个过程，让我们假设一个活塞机构(图2-3(a))，它是有两个阀Z0、Z1和贮液器连接而成，表面压力为P0，贮

液器内部压力为 P1，活塞处于上部的X=X0处，Z0打开，液体充满体积为V0的汽缸，压力为 P0，现在关闭阀Z0，并且开始向下移动活塞，如果 Z1关闭，当活塞下降到 X=X1处时，液体体积由V0变为V1，此时压力升至P1，驱动活塞所作的外部功是(假设热量改变)

W1=-∫X1X0(P-P0)Adx=-∫V1V0(P-P0)dv

制动器的应用

YWW系列电力液压块式制动器是一种常闭、卧式安装的制动器，主要用于门座式起重机、斗轮堆取料机以及中大型塔式起重机回转机构的制动。

YKW系列电力液压块式制动器是一种常开、卧式安装的制动器，推动器为闭合(上闸)驱动装置，它通过脚踏开关控制，司机在司机室内可随意空。主要用于门座式起重机和塔式起重机等回转机构的减速制动。当需要在机构断电时(非工作状态)进行制动，可通过增设手动闭合(上闸)来实现。

RKW系列制动器为常开式、液压驱动、卧式安装的制动器。通过脚踏式液压泵进行控制，可实现随意制动。主要用于中小型门座式起重机和塔式起重机的回转机构。带有手动闭合(上闸)装置，在非工作状态下有需要时，可通过其进行维持制动。 主要设计特点

联锁式退距均等装置，专利技术，在使用过程中可始终保持两侧瓦块制动衬浮贴制动轮的现象;设有瓦块自动随位装置。

主要摆动铰点均设有自动润滑轴承，传动效率高，寿命长，在使用过程中无需润滑。

设有可调式支撑装置，确保制动器工作灵活自如。

制动弹簧在方管内布置)(仅YWW产品)并在一侧设有标尺，用户可十分方便的读出制动力距值，免去测量和计算的麻烦。

制动衬垫为卡装式整体结构，更换十分方便，快捷，备有半金属(无石棉)硬质和半硬质，软质(含石棉)等不同材质的制动衬垫供用户选择。 全部采用本公司新型推动器配套，动作灵敏，寿命长。

第二篇：机械专业课程英文翻译

机械制图Descriptive Geometry & Engineering Graphing85

机械工程材料Mechanical Engineering Material90

工程力学Engineering Mechanics89

机械原理Principle of Mechanics85

机械原理课程设计Course Exercise for Principle of Mechanicsgood良好 机械设计Mechanical Design80

机械设计课程设计Course Exercise for Mechanical Designgood良好 液压与气压传动Hydraulic & Pneumatic Technology89

机械制造技术基础Fundamentals of Manufacturing Technology77

机械制造装备设计Modern Manufacturing Equipment Design84

电工与电子技术Mechanical Electric Electronic Control Technique86

微型计算机原理Principle and Application of Microcomputer81

互换性与测量技术Fundamentals of Exchangeability and Measurement Technology 77

机械工程控制基础Introduction to Control Engineering85

计算机数控技术Technology and Application of Numerical Control Programming 77

PLCPrinciple and Application of PLC82

模具制造技术Mould Manufacture Technology76

传感器与测试技术Measurement and Testing Technology81

计算机辅助设计Computer-aided Design86

机械系统设计Mechanical System Design88

生产实习Production Practical Traininggood良好

机械制图、机械工程材料、工程力学、机械原理、机械原理课程设计、机械设计、机械设计课程设计、液压与气压传动、机械制造技术基础、机械制造装备设计、电工与电子技术、微型计算机原理、互换性与测量技术、机械工程控制基础、计算机数控技术、PLC、模具制造技术、传感器与测试技术、计算机辅助设计、机械系统设计、生产实习等

由于在大二第一学期就过了英语6级，所以，从那个时候起，一直都在通过选修口语课，加入英语角，看美剧，晨读等方式学英语口语，因此口语水平良好，可以和以英语为母语的人进行交流。

Descriptive Geometry & Engineering Graphing85

Mechanical Engineering Material90

Engineering Mechanics89

Principle of Mechanics85

Course Exercise for Principle of Mechanicsgood

Mechanical Design80

Course Exercise for Mechanical Designgood

Hydraulic & Pneumatic Technology89

Fundamentals of Manufacturing Technology77

Modern Manufacturing Equipment Design84

Mechanical Electric Electronic Control Technique86 Principle and Application of Microcomputer81

Fundamentals of Exchangeability and Measurement Technology 77 Introduction to Control Engineering85

计Technology and Application of Numerical Control Programming Principle and Application of PLC82

Mould Manufacture Technology76

Measurement and Testing Technology81

Computer-aided Design86

Mechanical System Design88

Production Practical Traininggood

Course Exercise for Fundamentals of Manufacturing Technology

Course Exercise for Modern Manufacturing Equipment Design77

第三篇：机械专业英语文章中英文对照

英语原文

NUMERICAL CONTROL

Numerical control(N/C)is a form of programmable automation in which the processing equipment is controlled by means of numbers, letters, and other symbols, The numbers, letters, and symbols are coded in an appropriate format to define a program of instructions for a particular work part or job. When the job changes, the program of instructions is changed. The capability to change the program is what makes N/C suitable for low-and medium-volume production. It is much easier to write programs than to make major alterations of the processing equipment.

There are two basic types of numerically controlled machine tools：point—to—point and continuous—path(also called contouring).Point—to—point machines use unsynchronized motors, with the result that the position of the machining head Can be assured only upon completion of a movement, or while only one motor is running. Machines of this type are principally used for straight—line cuts or for drilling or boring.

The N/C system consists of the following components：data input, the tape reader with the control unit, feedback devices, and the metal—cutting machine tool or other type of N/C equipment.

Data input, also called “man—to—control link”, may be provided to the machine tool manually, or entirely by automatic means. Manual methods when used as the sole source of input data are restricted to a relatively small number of inputs. Examples of manually operated devices are keyboard dials, pushbuttons, switches, or thumbwheel selectors. These are located on a console near the machine. Dials ale analog devices usually connected to a syn-chro-type resolver or potentiometer. In most cases, pushbuttons, switches, and other similar types of selectors are digital input devices. Manual input requires that the operator set the controls for each operation. It is a slow and tedious process and is seldom justified except in elementary machining applications or in special cases.

In practically all cases, information is automatically supplied to the control unit and the machine tool by cards, punched tapes, or by magnetic tape. Eight—channel punched paper tape is the most commonly used form of data input for conventional N/C systems. The coded instructions on the tape consist of sections of punched holes called blocks. Each block represents a machine function, a machining operation, or a combination of the two. The entire N/C program on a tape is made up of an accumulation of these successive data blocks. Programs resulting in long tapes all wound on reels like motion-picture film. Programs on relatively short tapes may be continuously repeated by joining the two ends of the tape to form a loop. Once installed, the tape is used again and again without further handling. In this case, the operator simply loads and1

unloads the parts. Punched tapes ale prepared on type writers with special tape—punching attachments or in tape punching units connected directly to a computer system. Tape production is rarely error-free. Errors may be initially caused by the part programmer, in card punching or compilation, or as a result of physical damage to the tape during handling, etc. Several trial runs are often necessary to remove all errors and produce an acceptable working tape.

While the data on the tape is fed automatically, the actual programming steps ale done manually. Before the coded tape may be prepared, the programmer, often working with a planner or a process engineer, must select the appropriate N/C machine tool, determine the kind of material to be machined, calculate the speeds and feeds, and decide upon the type of tooling needed. The dimensions on the part print are closely examined to determine a suitable zero reference point from which to start the program. A program manuscript is then written which gives coded numerical instructions describing the sequence of operations that the machine tool is required to follow to cut the part to the drawing specifications.

The control unit receives and stores all coded data until a complete block of information has been accumulated. It then interprets the coded instruction and directs the machine tool through the required motions.

The function of the control unit may be better understood by comparing it to the action of a dial telephone, where, as each digit is dialed, it is stored. When the entire number has been dialed, the equipment becomes activated and the call is completed.

Silicon photo diodes, located in the tape reader head on the control unit, detect light as it passes through the holes in the moving tape. The light beams are converted to electrical energy, which is amplified to further strengthen the signal. The signals are then sent to registers in the control unit, where actuation signals are relayed to the machine tool drives.

Some photoelectric devices are capable of reading at rates up to 1000 characters per second. High reading rates are necessary to maintain continuous machine—tool motion;otherwise dwell marks may be generated by the cutter on the part during contouring operations. The reading device must be capable of reading data blocks at a rate faster than the control system can process the data.

A feedback device is a safeguard used on some N/C installations to constantly compensate for errors between the commanded position and the actual location of the moving slides of the machine tool. An N/C machine equipped with this kind of a direct feedback checking device has what is known as a closed-loop system. Positioning control is accomplished by a sensor which, during the actual operation, records the position of the slides and relays this information back to the control unit. Signals thus received ale compared to input signals on the tape, and any discrepancy between them is automatically rectified.

In an alternative system, called an open—loop system, the machine is positioned solely by stepping motor drives in response to commands by a controllers. There is one basic type of NC motions. Point-to-point or Positional Control In point-to-point control the machine tool elements (tools, table, etc.) are moved to programmed locations and the machining operations performed

after the motions are completed. The path or speed of movement between locations is unimportant; only the coordinates of the end points of the motions are accurately controlled. This type of control is suitable for drill presses and some boring machines, where drilling, tapping, or boring operations must be performed at various locations on the work piece. Straight-Line or Linear Control Straight-Line control systems are able to move the cutting tool parallel to one of the major axes of the machine tool at a controlled rate suitable for machining. It is normally only possible to move in one direction at a time, so angular cuts on the work piece are not possible, consequently, for milling machines, only rectangular configurations can be machined or for lathes only surfaces parallel or perpendicular to the spindle axis can be machined. This type of controlled motion is often referred to as linear control or a half-axis of control. Machines with this form of control are also capable of point-to-point control.

The original N/C used the closed—loop system. Of the two systems, closed and open loop, closed loop is more accurate and, as a consequence, is generally more expensive. Initially, open—loop systems were used almost entirely for light-duty applications because of inherent power limitations previously associated with conventional electric stepping motors. Recent advances in the development of electro hydraulic stepping motors have led to increasingly heavier machine load applications.中文译文

数控技术

数控是可编程自动化技术的一种形式,通过数字、字母和其他符号来控制加工设备。数字、字母和符号用适当的格式编码为一个特定工件定义指令程序。当工件改变时,指令程序就改变。这种改变程序的能力使数控适合于中、小批量生产,写一段新程序远比对加工设备做大的改动容易得多。

数控机床有两种基本形式：点位控制和连续控制(也称为轮廓控制)。点位控制机床采用异步电动机,因此,主轴的定位只能通过完成一个运动或一个电动机的转动来实现。这种机床主要用于直线切削或钻孔、镗孔等场合。

数控系统由下列组件组成：数据输入装置,带控制单元的磁带阅读机,反馈装置和切削机床或其他形式的数控设备。

数据输人装置,也称“人机联系装置”,可用人工或全自动方法向机床提供数据。人工方法作为输人数据唯一方法时,只限于少量输入。人工输入装置有键盘,拨号盘,按钮,开关或拨轮选择开关,这些都位于机床附近的一个控制台上。拨号盘通常连到一个同步解析器或电位计的模拟装置上。在大多数情况下,按钮、开关和其他类似的旋钮是数据输入元件。人工输入需要操作者控制每个操作,这是一个既慢又单调的过程,除了简单加工场合或特殊情况,已很少使用。

几乎所有情况下,信息都是通过卡片、穿孔纸带或磁带自动提供给控制单元。在传统的数控系统中,八信道穿孔纸带是最常用的数据输入形式,纸带上的编码指令由一系列称为程序块的穿孔组成。每一个程序块代表一种加工功能、一种操作或两者的组合。纸带上的整个数控程序由这些连续数据单元连接而成。带有程序的长带子像电影胶片一样绕在盘子上,相对较短的带子上的程序可通过将纸带两端连接形成一个循环而连续不断地重复使用。带子一旦安装好,就可反复使用而无需进一步处理。此时,操作者只是简单地上、下工件。穿孔纸带是在带有特制穿孔附件的打字机或直接连到计算机上的纸带穿孔装置上做成的。纸带制造很少不出错,错误可能由编程、卡片穿孔或编码、纸带穿孔时的物理损害等形成。通常,必须要试走几次来排除错误,才能得到一个可用的工作纸带。

虽然纸带上的数据是自动进给的,但实际编程却是手工完成的,在编码纸带做好前,编程者经常要和一个计划人员或工艺工程师一起工作,选择合适的数控机床,决定加工材料,计算切削速度和进给速度,决定所需刀具类型,仔细阅读零件图上尺寸,定下合适的程序开始的零参考点,然后写出程序清单,其上记载有描述加工顺序的编码数控指令,机床按顺序加工工件到图样要求。

控制单元接受和储存编码数据,直至形成一个完整的信息程序块,然后解释数控指令,并引导机床得到所需运动。

为更好理解控制单元的作用,可将它与拨号电话进行比较,即每拨一个数字,就储存一个,当整个数字拨好后,电话就被激活,也就完成了呼叫。

装在控制单元里的纸带阅读机,通过其内的硅光二极管,检测到穿过移动纸带上的孔漏

过的光线,将光束转变成电能,并通过放大来进一步加强信号,然后将信号送到控制单元里的寄存器,由它将动作信号传到机床驱动装置。

有些光电装置能以高达每秒1000个字节的速度阅读,这对保持机床连续动作是必须的,否则,在轮廓加工时,刀具可能在工件上产生划痕。阅读装置必须要能以比控制系统处理数据更快的速度来阅读数据程序块。

反馈装置是用在一些数控设备上的安全装置,它可连续补偿控制位置与机床运动滑台的实际位置之间的误差。装有这种直接反馈检查装置的数控机床有一个闭环系统装置。位置控制通过传感器实现,在实际工作时,记录下滑台的位置,并将这些信息送回控制单元。接受到的信号与纸带输入的信号相比较,它们之间的任何偏差都可得到纠正。

在另一个称为开环的系统中,机床仅由响应控制器命令的步进电动机驱动定位,工件的精度几乎完全取决于丝杠的精度和机床结构的刚度。有几个理由可以说明步进电机是一个自动化申请的非常有用的驱动装置。对于一件事物,它被不连续直流电压脉冲驱使,是来自数传计算机和其他的自动化的非常方便的输出控制系统。当多数是索引或其他的自动化申请所必备者的时候,步进电机对运行一个精确的有角进步也是理想的。因为控制系统不需要监听就提供特定的输出指令而且期待系统适当地反应的公开- 环操作造成一个回应环,步进电机是理想的。 一些工业的机械手使用高抬腿运步的马乘汽车驾驶员,而且步进电机是有用的在数字受约束的工作母机中。 这些申请的大部分是公开- 环 ,但是雇用回应环检测受到驱策的成份位置是可能的。 环的一个分析者把真实的位置与需要的位置作比较,而且不同是考虑过的错误。 那然后驾驶员能发行对步进电机的电脉冲,直到错误被减少对准零位。在这个系统中,没有信息反馈到控制单元的自矫正过程。出现误动作时,控制单元继续发出电脉冲。比如,一台数控铣床的工作台突然过载,阻力矩超过电机转矩时,将没有响应信号送回到控制器。因为,步进电机对载荷变化不敏感,所以许多数控系统设计允许电机停转。然而,尽管有可能损坏机床结构或机械传动系统,也有使用带有特高转矩步进电机的其他系统,此时,电动机有足够能力来应付系统中任何偶然事故。

最初的数控系统采用开环系统。在开、闭环两种系统中,闭环更精确,一般说来更昂贵。起初,因为原先传统的步进电动机的功率限制,开环系统几乎全部用于轻加工场合,最近出现的电液步进电动机已越来越多地用于较重的加工领域。

第四篇：机械专业英语文章 中英文对照

Types of Materials 材料的类型

Materials may be grouped in several ways. Scientists often classify materials by their state: solid, liquid, or gas. They also separate them into organic (once living) and inorganic (never living) materials. 材料可以按多种方法分类。科学家常根据状态将材料分为：固体、液体或气体。他们也把材料分为有机材料(曾经有生命的)和无机材料(从未有生命的)。

For industrial purposes, materials are divided into engineering materials or nonengineering materials. Engineering materials are those used in manufacture and become parts of products. 就工业效用而言，材料被分为工程材料和非工程材料。那些用于加工制造并成为产品组成部分的就是工程材料。

Nonengineering materials are the chemicals, fuels, lubricants, and other materials used in the manufacturing process, which do not become part of the product. 非工程材料则是化学品、燃料、润滑剂以及其它用于加工制造过程但不成为产品组成部分的材料。

Engineering materials may be further subdivided into: ①Metal ②Ceramics ③Composite ④Polymers, etc.

1

工程材料还能进一步细分为：①金属材料②陶瓷材料③复合材料 ④聚合材料，等等。

Metals and Metal Alloys 金属和金属合金

Metals are elements that generally have good electrical and thermal conductivity. Many metals have high strength, high stiffness, and have good ductility. 金属就是通常具有良好导电性和导热性的元素。许多金属具有高强度、高硬度以及良好的延展性。

Some metals, such as iron, cobalt and nickel, are magnetic. At low temperatures, some

metals

and

intermetallic

compounds

become superconductors. 某些金属能被磁化，例如铁、钴和镍。在极低的温度下，某些金属和金属化合物能转变成超导体。

What is the difference between an alloy and a pure metal? Pure metals are elements which come from a particular area of the periodic table. Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans. 合金与纯金属的区别是什么?纯金属是在元素周期表中占据特定位置的元素。

2

例如电线中的铜和制造烹饪箔及饮料罐的铝。

Alloys contain more than one metallic element. Their properties can be changed by changing the elements present in the alloy. Examples of metal alloys include stainless steel which is an alloy of iron, nickel, and chromium; and gold jewelry which usually contains an alloy of gold and nickel. 合金包含不止一种金属元素。合金的性质能通过改变其中存在的元素而改变。金属合金的例子有：不锈钢是一种铁、镍、铬的合金，以及金饰品通常含有金镍合金。

Why are metals and alloys used? Many metals and alloys have high densities and are used in applications which require a high mass-to-volume ratio. 为什么要使用金属和合金?许多金属和合金具有高密度，因此被用在需要较高质量体积比的场合。

Some metal alloys, such as those based on aluminum, have low densities and are used in aerospace applications for fuel economy. Many alloys also have high fracture toughness, which means they can withstand impact and are durable. 某些金属合金，例如铝基合金，其密度低，可用于航空航天以节约燃料。许多合金还具有高断裂韧性，这意味着它们能经得起冲击并且是耐用的

What are some important properties of metals?

3

Density is defined as a material’s mass divided by its volume. Most metals have relatively high densities, especially compared to polymers. 金属有哪些重要特性?

密度定义为材料的质量与其体积之比。大多数金属密度相对较高，尤其是和聚合物相比较而言。

Materials with high densities often contain atoms with high atomic numbers, such as gold or lead. However, some metals such as aluminum or magnesium have low densities, and are used in applications that require other metallic properties but also require low weight. 高密度材料通常由较大原子序数原子构成，例如金和铅。然而，诸如铝和镁之类的一些金属则具有低密度，并被用于既需要金属特性又要求重量轻的场合。

Fracture toughness can be described as a material’s ability to avoid fracture, especially when a flaw is introduced. Metals can generally contain nicks and dents without weakening very much, and are impact resistant. A football player counts on this when he trusts that his facemask won’t shatter. 断裂韧性可以描述为材料防止断裂特别是出现缺陷时不断裂的能力。金属一般能在有缺口和凹痕的情况下不显著削弱，并且能抵抗冲击。橄榄球运动员据此相信他的面罩不会裂成碎片。

Plastic deformation is the ability of bend or deform before breaking.

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As engineers, we usually design materials so that they don’t deform under normal conditions. You don’t want your car to lean to the east after a strong west wind. 塑性变形就是在断裂前弯曲或变形的能力。作为工程师，设计时通常要使材料在正常条件下不变形。没有人愿意一阵强烈的西风过后自己的汽车向东倾斜。

However, sometimes we can take advantage of plastic deformation. The crumple zones in a car absorb energy by undergoing plastic deformation before they break. 然而，有时我们也能利用塑性变形。汽车上压皱的区域在它们断裂前通过经历塑性变形来吸收能量。

The atomic bonding of metals also affects their properties. In metals, the outer valence electrons are shared among all atoms, and are free to travel everywhere. Since electrons conduct heat and electricity, metals make good cooking pans and electrical wires. 金属的原子连结对它们的特性也有影响。在金属内部，原子的外层阶电子由所有原子共享并能到处自由移动。由于电子能导热和导电，所以用金属可以制造好的烹饪锅和电线。

It is impossible to see through metals, since these valence electrons absorb any photons of light which reach the metal. No photons pass through. 因为这些阶电子吸收到达金属的光子，所以透过金属不可能看得见。没有光子

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能通过金属。

Alloys are compounds consisting of more than one metal. Adding other metals can affect the density, strength, fracture toughness, plastic deformation, electrical conductivity and environmental degradation. 合金是由一种以上金属组成的混合物。加一些其它金属能影响密度、强度、断裂韧性、塑性变形、导电性以及环境侵蚀。

For example, adding a small amount of iron to aluminum will make it stronger. Also, adding some chromium to steel will slow the rusting process, but will make it more brittle. 例如，往铝里加少量铁可使其更强。同样，在钢里加一些铬能减缓它的生锈过程，但也将使它更脆。

Ceramics and Glasses 陶瓷和玻璃

A ceramic is often broadly defined as any inorganic nonmetallic material. By this definition, ceramic materials would also include glasses; however, many materials scientists add the stipulation that “ceramic” must also be crystalline. 陶瓷通常被概括地定义为无机的非金属材料。照此定义，陶瓷材料也应包括玻璃;然而许多材料科学家添加了“陶瓷”必须同时是晶体物组成的约定。

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A glass is an inorganic nonmetallic material that does not have a crystalline structure. Such materials are said to be amorphous. 玻璃是没有晶体状结构的无机非金属材料。这种材料被称为非结晶质材料。 Properties of Ceramics and Glasses Some of the useful properties of ceramics and glasses include high melting temperature, low density, high strength, stiffness, hardness, wear resistance, and corrosion resistance. 陶瓷和玻璃的特性

高熔点、低密度、高强度、高刚度、高硬度、高耐磨性和抗腐蚀性是陶瓷和玻璃的一些有用特性。

Many ceramics are good electrical and thermal insulators. Some ceramics have special properties: some ceramics are magnetic materials; some are piezoelectric materials; and a few special ceramics are superconductors at very low temperatures. Ceramics and glasses have one major drawback: they are brittle. 许多陶瓷都是电和热的良绝缘体。某些陶瓷还具有一些特殊性能：有些是磁性材料，有些是压电材料，还有些特殊陶瓷在极低温度下是超导体。陶瓷和玻璃都有一个主要的缺点：它们容易破碎。

Ceramics are not typically formed from the melt. This is because most

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ceramics will crack extensively (i.e. form a powder) upon cooling from the liquid state. 陶瓷一般不是由熔化形成的。因为大多数陶瓷在从液态冷却时将会完全破碎(即形成粉末)。

Hence, all the simple and efficient manufacturing techniques used for glass production such as casting and blowing, which involve the molten state, cannot be used for the production of crystalline ceramics. Instead, “sintering” or “firing” is the process typically used.

因此，所有用于玻璃生产的简单有效的—诸如浇铸和吹制这些涉及熔化的技术都不能用于由晶体物组成的陶瓷的生产。作为替代，一般采用“烧结”或“焙烧”工艺。

In sintering, ceramic powders are processed into compacted shapes and then heated to temperatures just below the melting point. At such temperatures, the powders react internally to remove porosity and fully dense articles can be obtained. 在烧结过程中，陶瓷粉末先挤压成型然后加热到略低于熔点温度。在这样的温度下，粉末内部起反应去除孔隙并得到十分致密的物品。

An optical fiber contains three layers: a core made of highly pure glass with a high refractive index for the light to travel, a middle layer of glass with a lower refractive index known as the cladding which protects the core

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glass from scratches and other surface imperfections, and an out polymer jacket to protect the fiber from damage. 光导纤维有三层：核心由高折射指数高纯光传输玻璃制成，中间层为低折射指数玻璃，是保护核心玻璃表面不被擦伤和完整性不被破坏的所谓覆层，外层是聚合物护套，用于保护光导纤维不受损。

In order for the core glass to have a higher refractive index than the cladding, the core glass is doped with a small, controlled amount of an impurity, or dopant, which causes light to travel slower, but does not absorb the light. 为了使核心玻璃有比覆层大的折射指数，在其中掺入微小的、可控数量的能减缓光速而不会吸收光线的杂质或搀杂剂。

Because the refractive index of the core glass is greater than that of the cladding, light traveling in the core glass will remain in the core glass due to total internal reflection as long as the light strikes the core/cladding interface at an angle greater than the critical angle. 由于核心玻璃的折射指数比覆层大，只要在全内反射过程中光线照射核心/覆层分界面的角度比临界角大，在核心玻璃中传送的光线将仍保留在核心玻璃中。

The total internal reflection phenomenon, as well as the high purity of the core glass, enables light to travel long distances with little loss of intensity.

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全内反射现象与核心玻璃的高纯度一样，使光线几乎无强度损耗传递长距离成为可能。

Composites 复合材料

Composites are formed from two or more types of materials. Examples include polymer/ceramic and metal/ceramic composites. Composites are used because overall properties of the composites are superior to those of the individual components. 复合材料由两种或更多材料构成。例子有聚合物/陶瓷和金属/陶瓷复合材料。之所以使用复合材料是因为其全面性能优于组成部分单独的性能。

For example: polymer/ceramic composites have a greater modulus than the polymer component, but aren’t as brittle as ceramics.

Two types of composites are: fiber-reinforced composites and particle-reinforced composites. 例如：聚合物/陶瓷复合材料具有比聚合物成分更大的模量，但又不像陶瓷那样易碎。

复合材料有两种：纤维加强型复合材料和微粒加强型复合材料。 Fiber-reinforced Composites Reinforcing fibers can be made of metals, ceramics, glasses, or polymers that have been turned into graphite and known as carbon fibers. Fibers

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increase the modulus of the matrix material. 纤维加强型复合材料

加强纤维可以是金属、陶瓷、玻璃或是已变成石墨的被称为碳纤维的聚合物。纤维能加强基材的模量。

The strong covalent bonds along the fiber’s length give them a very high modulus in this direction because to break or extend the fiber the bonds must also be broken or moved. 沿着纤维长度有很强结合力的共价结合在这个方向上给予复合材料很高的模量，因为要损坏或拉伸纤维就必须破坏或移除这种结合。

Fibers are difficult to process into composites, making fiber-reinforced composites relatively expensive. 把纤维放入复合材料较困难，这使得制造纤维加强型复合材料相对昂贵。 Fiber-reinforced composites are used in some of the most advanced, and therefore most expensive sports equipment, such as a time-trial racing bicycle frame which consists of carbon fibers in a thermoset polymer matrix. 纤维加强型复合材料用于某些最先进也是最昂贵的运动设备，例如计时赛竞赛用自行车骨架就是用含碳纤维的热固塑料基材制成的。

Body parts of race cars and some automobiles are composites made of glass fibers (or fiberglass) in a thermoset matrix.

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竞赛用汽车和某些机动车的车体部件是由含玻璃纤维(或玻璃丝)的热固塑料基材制成的。

Fibers have a very high modulus along their axis, but have a low modulus perpendicular to their axis. Fiber composite manufacturers often rotate layers of fibers to avoid directional variations in the modulus. 纤维在沿着其轴向有很高的模量，但垂直于其轴向的模量却较低。纤维复合材料的制造者往往旋转纤维层以防模量产生方向变化。

Particle-reinforced composites Particles used for reinforcing include ceramics and glasses such as small mineral particles, metal particles such as aluminum, and amorphous materials, including polymers and carbon black. 微粒加强型复合材料[番茄用户1] [番茄用户2] [番茄用户3] [番茄用户4] [番茄用户5] [番茄用户6] 用于加强的微粒包含了陶瓷和玻璃之类的矿物微粒，铝之类的金属微粒以及包括聚合物和碳黑的非结晶质微粒。

Particles are used to increase the modulus of the matrix, to decrease the permeability of the matrix, to decrease the ductility of the matrix. An example of particle-reinforced composites is an automobile tire which has carbon black particles in a matrix of polyisobutylene elastomeric polymer.

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微粒用于增加基材的模量、减少基材的渗透性和延展性。微粒加强型复合材料的一个例子是机动车胎，它就是在聚异丁烯人造橡胶聚合物基材中加入了碳黑微粒。

Polymers 聚合材料

A polymer has a repeating structure, usually based on a carbon backbone. The repeating structure results in large chainlike molecules. Polymers are useful because they are lightweight, corrosion resistant, easy to process at low temperatures and generally inexpensive. 聚合物具有一般是基于碳链的重复结构。这种重复结构产生链状大分子。由于重量轻、耐腐蚀、容易在较低温度下加工并且通常较便宜，聚合物是很有用的。

Some important characteristics of polymers include their size (or molecular weight), softening and melting points, crystallinity, and structure. The mechanical properties of polymers generally include low strength and high toughness. Their strength is often improved using reinforced composite structures. 聚合材料具有一些重要特性，包括尺寸(或分子量)、软化及熔化点、结晶度和结构。聚合材料的机械性能一般表现为低强度和高韧性。它们的强度通常可采用加强复合结构来改善。

Important Characteristics of Polymers Size. Single polymer molecules typically have molecular weights between 10,000 and 1,000,000g/mol—that can be more than 2,000 repeating units

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depending on the polymer structure! 聚合材料的重要特性

尺寸：单个聚合物分子一般分子量为10,000到1,000,000g/mol之间，具体取决于聚合物的结构—这可以比2,000个重复单元还多。

The mechanical properties of a polymer are significantly affected by the molecular weight, with better engineering properties at higher molecular weights. 聚合物的分子量极大地影响其机械性能，分子量越大，工程性能也越好。 Thermal transitions. The softening point (glass transition temperature) and the melting point of a polymer will determine which it will be suitable for applications. These temperatures usually determine the upper limit for which a polymer can be used. 热转换性：聚合物的软化点(玻璃状转化温度)和熔化点决定了它是否适合应用。这些温度通常决定聚合物能否使用的上限。

For example, many industrially important polymers have glass transition temperatures near the boiling point of water (100℃, 212℉), and they are most useful for room temperature applications. Some specially engineered polymers can withstand temperatures as high as 300℃(572℉).

例如，许多工业上的重要聚合物其玻璃状转化温度接近水的沸点(100℃,

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212℉)，它们被广泛用于室温下。而某些特别制造的聚合物能经受住高达300℃(572℉)的温度。

Crystallinity. Polymers can be crystalline or amorphous, but they usually have a combination of crystalline and amorphous structures (semi-crystalline). 结晶度：聚合物可以是晶体状的或非结晶质的，但它们通常是晶体状和非结晶质结构的结合物(半晶体)。

Interchain interactions. The polymer chains can be free to slide past one another (thermo-plastic) or they can be connected to each other with crosslinks (thermoset or elastomer). Thermo-plastics can be reformed and recycled, while thermosets and elastomers are not reworkable. 原子链间的相互作用：聚合物的原子链可以自由地彼此滑动(热可塑性)或通过交键互相连接(热固性或弹性)。热可塑性材料可以重新形成和循环使用，而热固性与弹性材料则是不能再使用的。

Intrachain structure. The chemical structure of the chains also has a tremendous effect on the properties. Depending on the structure the polymer may be hydrophilic or hydrophobic (likes or hates water), stiff or flexible, crystalline or amorphous, reactive or unreactive. 链内结构：原子链的化学结构对性能也有很大影响。根据各自的结构不同，聚合物可以是亲水的或憎水的(喜欢或讨厌水)、硬的或软的、晶体状的或非结晶质的、

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易起反应的或不易起反应的。

The understanding of heat treatment is embraced by the broader study of metallurgy. Metallurgy is the physics, chemistry, and engineering related to metals from ore extraction to the final product. 对热处理的理解包含于对冶金学较广泛的研究。冶金学是物理学、化学和涉及金属从矿石提炼到最后产物的工程学。

Heat treatment is the operation of heating and cooling a metal in its solid state to change its physical properties. According to the procedure used, steel can be hardened to resist cutting action and abrasion, or it can be softened to permit machining. 热处理是将金属在固态加热和冷却以改变其物理性能的操作。按所采用的步骤，钢可以通过硬化来抵抗切削和磨损，也可以通过软化来允许机加工。

With the proper heat treatment internal stresses may be removed, grain size reduced, toughness increased, or a hard surface produced on a ductile interior. The analysis of the steel must be known because small percentages of certain elements, notably carbon, greatly affect the physical properties. 使用合适的热处理可以去除内应力、细化晶粒、增加韧性或在柔软材料上覆盖坚硬的表面。因为某些元素(尤其是碳)的微小百分比极大地影响物理性能，所以必须知道对钢的分析。

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Alloy steel owe their properties to the presence of one or more elements other than carbon, namely nickel, chromium, manganese, molybdenum, tungsten, silicon, vanadium, and copper. Because of their improved physical properties they are used commercially in many ways not possible with carbon steels. 合金钢的性质取决于其所含有的除碳以外的一种或多种元素，如镍、铬、锰、钼、钨、硅、钒和铜。由于合金钢改善的物理性能，它们被大量使用在许多碳钢不适用的地方。

The following discussion applies principally to the heat treatment of ordinary commercial steels known as plain carbon steels. With this process the rate of cooling is the controlling factor, rapid cooling from above the critical range results in hard structure, whereas very slow cooling produces the opposite effect. 下列讨论主要针对被称为普通碳钢的工业用钢而言。热处理时冷却速率是控制要素，从高于临界温度快速冷却导致坚硬的组织结构，而缓慢冷却则产生相反效果。

A Simplified Iron-carbon Diagram 简化铁碳状态图

If we focus only on the materials normally known as steels, a simplified diagram is often used. 如果只把注意力集中于一般所说的钢上，经常要用到简化铁碳状态图。

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Those portions of the iron-carbon diagram near the delta region and those above 2% carbon content are of little importance to the engineer and are deleted. A simplified diagram, such as the one in Fig.2.1, focuses on the eutectoid region and is quite useful in understanding the properties and processing of steel. 铁碳状态图中靠近三角区和含碳量高于2%的那些部分对工程师而言不重要，因此将它们删除。如图2.1所示的简化铁碳状态图将焦点集中在共析区，这对理解钢的性能和处理是十分有用的。

The key transition described in this diagram is the decomposition of single-phase austenite(γ) to the two-phase ferrite plus carbide structure as temperature drops. 在此图中描述的关键转变是单相奥氏体(γ) 随着温度下降分解成两相铁素体加渗碳体组织结构。

Control of this reaction, which arises due to the drastically different carbon solubility of austenite and ferrite, enables a wide range of properties to be achieved through heat treatment. 控制这一由于奥氏体和铁素体的碳溶解性完全不同而产生的反应，使得通过热处理能获得很大范围的特性。

To begin to understand these processes, consider a steel of the eutectoid composition, 0.77% carbon, being slow cooled along line x-x’ in

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Fig.2.1. At the upper temperatures, only austenite is present, the 0.77% carbon being dissolved in solid solution with the iron. When the steel cools to 727℃(1341℉), several changes occur simultaneously.

为了理解这些过程，考虑含碳量为0.77%的共析钢，沿着图2.1的x-x’线慢慢冷却。在较高温度时，只存在奥氏体，0.77%的碳溶解在铁里形成固溶体。当钢冷却到727℃ (1341℉)时，将同时发生若干变化。

The iron wants to change from the FCC austenite structure to the BCC ferrite structure, but the ferrite can only contain 0.02% carbon in solid solution. 铁需要从面心立方体奥氏体结构转变为体心立方体铁素体结构，但是铁素体只能容纳固溶体状态的0.02%的碳。

The rejected carbon forms the carbon-rich cementite intermetallic with composition Fe3C. In essence, the net reaction at the eutectoid is austenite 0.77%C→ferrite 0.02%C+cementite 6.67%C.

被析出的碳与金属化合物Fe3C形成富碳的渗碳体。本质上，共析体的基本反应是奥氏体0.77%的碳→铁素体0.02%的碳+渗碳体6.67%的碳。

Since this chemical separation of the carbon component occurs entirely in the solid state, the resulting structure is a fine mechanical mixture of ferrite and cementite. Specimens prepared by polishing and etching in a weak solution of nitric acid and alcohol reveal the lamellar structure of

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alternating plates that forms on slow cooling. 由于这种碳成分的化学分离完全发生在固态中，产生的组织结构是一种细致的铁素体与渗碳体的机械混合物。通过打磨并在弱硝酸酒精溶液中蚀刻制备的样本显示出由缓慢冷却形成的交互层状的薄片结构。

This structure is composed of two distinct phases, but has its own set of characteristic properties and goes by the name pearlite, because of its resemblance to mother- of- pearl at low magnification. 这种结构由两种截然不同的状态组成，但它本身具有一系列特性，且因与低倍数放大时的珠母层有类同之处而被称为珠光体。

Steels having less than the eutectoid amount of carbon (less than 0.77%) are known as hypo-eutectoid steels. Consider now the transformation of such a material represented by cooling along line y-y’ in Fig.2.1.

含碳量少于共析体(低于0.77%)的钢称为亚共析钢。现在来看这种材料沿着图2.1中y-y’ 线冷却的转变情况。

At high temperatures, the material is entirely austenite, but upon cooling enters a region where the stable phases are ferrite and austenite. Tie-line and level-law calculations show that low-carbon ferrite nucleates and grows, leaving the remaining austenite richer in carbon. 在较高温度时，这种材料全部是奥氏体，但随着冷却就进入到铁素体和奥氏体稳定状态的区域。由截线及杠杆定律分析可知，低碳铁素体成核并长大，剩下含碳

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量高的奥氏体。

At 727℃(1341℉), the austenite is of eutectoid composition (0.77% carbon) and further cooling transforms the remaining austenite to pearlite. The resulting structure is a mixture of primary or pro-eutectoid ferrite (ferrite that formed above the eutectoid reaction) and regions of pearlite. 在727℃(1341℉)时，奥氏体为共析组成(含碳量0.77%)，再冷却剩余的奥氏体就转化为珠光体。作为结果的组织结构是初步的共析铁素体(在共析反应前的铁素体)和部分珠光体的混合物。

Hypereutectoid steels are steels that contain greater than the eutectoid amount of carbon. When such steel cools, as shown in z-z’ of Fig.2.1 the process is similar to the hypo-eutectoid case, except that the primary or pro-eutectoid phase is now cementite instead of ferrite. 过共析钢是含碳量大于共析量的钢。当这种钢冷却时，就像图2.1的z-z’线所示，除了初步的共析状态用渗碳体取代铁素体外，其余类似亚共析钢的情况。

As the carbon-rich phase forms, the remaining austenite decreases in carbon content, reaching the eutectoid composition at 727℃(1341℉). As before, any remaining austenite transforms to pearlite upon slow cooling through this temperature. 随着富碳部分的形成，剩余奥氏体含碳量减少，在727℃(1341℉)时达到共析组

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织。就像以前说的一样，当缓慢冷却到这温度时所有剩余奥氏体转化为珠光体。

It should be remembered that the transitions that have been described by the phase diagrams are for equilibrium conditions, which can be approximated by slow cooling. With slow heating, these transitions occur in the reverse manner. 应该记住由状态图描述的这种转化只适合于通过缓慢冷却的近似平衡条件。如果缓慢加热，则以相反的方式发生这种转化。

However, when alloys are cooled rapidly, entirely different results may be obtained, because sufficient time is not provided for the normal phase reactions to occur, in such cases, the phase diagram is no longer a useful tool for engineering analysis. 然而，当快速冷却合金时，可能得到完全不同的结果。因为没有足够的时间让正常的状态反应发生，在这种情况下对工程分析而言状态图不再是有用的工具。

Hardening 淬火

Hardening is the process of heating a piece of steel to a temperature within or above its critical range and then cooling it rapidly. 淬火就是把钢件加热到或超过它的临界温度范围，然后使其快速冷却的过程。 If the carbon content of the steel is known, the proper temperature to which the steel should be heated may be obtained by reference to the iron-iron

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carbide phase diagram. However, if the composition of the steel is unknown, a little preliminary experimentation may be necessary to determine the range. 如果钢的含碳量已知，钢件合适的加热温度可参考铁碳合金状态图得到。然而当钢的成分不知道时，则需做一些预备试验来确定其温度范围。

A good procedure to follow is to heat-quench a number of small specimens of the steel at various temperatures and observe the result, either by hardness testing or by microscopic examination. When the correct temperature is obtained, there will be a marked change in hardness and other properties. 要遵循的合适步骤是将这种钢的一些小试件加热到不同的温度后淬火，再通过硬度试验或显微镜检查观测结果。一旦获得正确的温度，硬度和其它性能都将有明显的变化。

In any heat-treating operation the rate of heating is important. Heat flows from the exterior to the interior of steel at a definite rate. If the steel is heated too fast, the outside becomes hotter than the interior and uniform structure cannot be obtained. 在任何热处理作业中，加热的速率都是重要的。热量以一定的速率从钢的外部传导到内部。如果钢被加热得太快，其外部比内部热就不能得到均匀的组织结构。

If a piece is irregular in shape, a slow rate is all the more essential to eliminate warping and cracking. The heavier the section, the longer must be the heating time to achieve uniform results.

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如果工件形状不规则，为了消除翘曲和开裂最根本的是加热速率要缓慢。截面越厚，加热的时间就要越长才能达到均匀的结果。

Even after the correct temperature has been reached, the piece should be held at that temperature for a sufficient period of time to permit its thickest section to attain a uniform temperature. 即使加热到正确的温度后，工件也应在此温度下保持足够时间以让其最厚截面达到相同温度。

The hardness obtained from a given treatment depends on the quenching rate, the carbon content, and the work size. In alloy steels the kind and amount of alloying element influences only the hardenability (the ability of the workpiece to be hardened to depths) of the steel and does not affect the hardness except in unhardened or partially hardened steels. 通过给定的热处理所得到的硬度取决于淬火速率、含碳量和工件尺寸。除了非淬硬钢或部分淬硬钢外，合金钢中合金元素的种类及含量仅影响钢的淬透性(工件被硬化到深层的能力)而不影响硬度。

Steel with low carbon content will not respond appreciably to hardening treatment. As the carbon content in steel increases up to around 0.60%, the possible hardness obtainable also increases. 含碳量低的钢对淬火处理没有明显的反应。随着钢的含碳量增加到大约0.60%，可能得到的硬度也增加。

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Above this point the hardness can be increased only slightly, because steels above the eutectoid point are made up entirely of pearlite and cementite in the annealed state. Pearlite responds best to heat-treating operations; and steel composed mostly of pearlite can be transformed into a hard steel. 高于此点，由于超过共析点钢完全由珠光体和退火状态的渗碳体组成，硬度增加并不多。珠光体对热处理作业响应最好;基本由珠光体组成的钢能转化成硬质钢。

As the size of parts to be hardened increases, the surface hardness decreases somewhat even though all other conditions have remained the same. There is a limit to the rate of heat flow through steel. 即使所有其它条件保持不变，随着要淬火的零件尺寸的增加其表面硬度也会有所下降。热量在钢中的传导速率是有限的。

No matter how cool the quenching medium may be, if the heat inside a large piece cannot escape faster than a certain critical rate, there is a definite limit to the inside hardness. However, brine or water quenching is capable of rapidly bringing the surface of the quenched part to its own temperature and maintaining it at or close to this temperature. 无论淬火介质怎么冷，如果在大工件中的热量不能比特定的临界速率更快散发，那它内部硬度就会受到明确限制。然而盐水或水淬火能够将被淬零件的表面迅速冷却至本身温度并将其保持或接近此温度。

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Under these circumstances there would always be some finite depth of surface hardening regardless of size. This is not true in oil quenching, when the surface temperature may be high during the critical stages of quenching. 在这种情况下不管零件尺寸如何，其表面总归有一定深度被硬化。但油淬情况就不是如此，因为油淬时在淬火临界阶段零件表面的温度可能仍然很高。

Tempering 回火

Steel that has been hardened by rapid quenching is brittle and not suitable for most uses. By tempering or drawing, the hardness and brittleness may be reduced to the desired point for service conditions.

快速淬火硬化的钢是硬而易碎的，不适合大多数场合使用。通过回火，硬度和脆性可以降低到使用条件所需要的程度。

As these properties are reduced there is also a decrease in tensile strength and an increase in the ductility and toughness of the steel. The operation consists of reheating quench-hardened steel to some temperature below the critical range followed by any rate of cooling. 随着这些性能的降低，拉伸强度也降低而钢的延展性和韧性则会提高。回火作业包括将淬硬钢重新加热到低于临界范围的某一温度然后以任意速率冷却。

Although this process softens steel, it differs considerably from annealing in that the process lends itself to close control of the physical properties and in most cases does not soften the steel to the extent that

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annealing would. The final structure obtained from tempering a fully hardened steel is called tempered martensite. 虽然这过程使钢软化，但它与退火是大不相同的，因为回火适合于严格控制物理性能并在大多数情况下不会把钢软化到退火那种程度。回火完全淬硬钢得到的最终组织结构被称为回火马氏体。

Tempering is possible because of the instability of the martensite, the principal constituent of hardened steel. Low-temperature draws, from 300℉ to 400℉ (150℃~205℃), do not cause much decrease in hardness and are used principally to relieve internal strains. 由于马氏体这一淬硬钢主要成分的不稳定性，使得回火成为可能。低温回火， 300℉到400℉(150℃~205℃)，不会引起硬度下降很多，主要用于减少内部应变。

As the tempering temperatures are increased, the breakdown of the martensite takes place at a faster rate, and at about 600℉(315℃) the change to a structure called tempered martensite is very rapid. The tempering operation may be described as one of precipitation and agglomeration or coalescence of cementite. 随着回火温度的提高，马氏体以较快的速率分解，并在大约600℉(315℃)迅速转变为被称为回火马氏体的结构。回火作业可以描述为渗碳体析出和凝聚或聚结的过程。

A substantial precipitation of cementite begins at 600℉(315℃), which

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produces a decrease in hardness. Increasing the temperature causes coalescence of the carbides with continued decrease in hardness. 渗碳体的大量析出开始于600℉(315℃)，这使硬度下降。温度的上升会使碳化物聚结而硬度继续降低。

In the process of tempering, some consideration should be given to time as well as to temperature. Although most of the softening action occurs in the first few minutes after the temperature is reached, there is some additional reduction in hardness if the temperature is maintained for a prolonged time. 在回火过程中，不但要考虑温度而且要考虑时间。虽然大多数软化作用发生在达到所需温度后的最初几分钟，但如果此温度维持一段延长时间，仍会有些额外的硬度下降。

Usual practice is to heat the steel to the desired temperature and hold it there only long enough to have it uniformly heated. 通常的做法是将钢加热到所需温度并且仅保温到正好使其均匀受热。

Two special processes using interrupted quenching are a form of tempering. In both, the hardened steel is quenched in a salt bath held at a selected lower temperature before being allowed to cool. These processes, known as austempering and martempering, result in products having certain desirable physical properties.

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两种采用中断淬火的特殊工艺也是回火的形式。这两种工艺中，淬硬钢在其被允许冷却前先在一选定的较低温度盐浴淬火。这两种分别被称为奥氏体回火和马氏体回火的工艺，能使产品具有特定所需的物理性能。

Annealing 退火

The primary purpose of annealing is to soften hard steel so that it may be machined or cold worked. 退火的主要目的是使坚硬的钢软化以便机加工或冷作。

This is usually accomplished by heating the steel too slightly above the critical temperature, holding it there until the temperature of the piece is uniform throughout, and then cooling at a slowly controlled rate so that the temperature of the surface and that of the center of the piece are approximately the same. 通常是非常缓慢地将钢加热到临界温度以上，并将其在此温度下保持到工件全部均匀受热，然后以受控的速率慢慢地冷却，这样使得工件表面和内部的温度近似相同。

This process is known as full annealing because it wipes out all trace of previous structure, refines the crystalline structure, and softens the metal. Annealing also relieves internal stresses previously set up in the metal. 这过程被称为完全退火，因为它去除了以前组织结构的所有痕迹、细化晶粒并

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软化金属。退火也释放了先前在金属中的内应力。

The temperature to which a given steel should be heated in annealing depends on its composition; for carbon steels it can be obtained readily from the partial iron-iron carbide equilibrium diagram. When the annealing temperature has been reached, the steel should be held there until it is uniform throughout. 给定的钢其退火温度取决于它的成分;对碳钢而言可容易地从局部的铁碳合金平衡图得到。达到退火温度后，钢应当保持在此温度等到全部均匀受热。

This usually takes about 45min for each inch(25mm) of thickness of the largest section. For maximum softness and ductility the cooling rate should be very slow, such as allowing the parts to cool down with the furnace. The higher the carbon content, the slower this rate must be. 加热时间一般以工件的最大截面厚度计每英寸(25mm )大约需45min。为了得到最大柔软性和延展性冷却速率应该很慢，比如让零件与炉子一起冷下来。含碳量越高，冷却的速率必须越慢。

The heating rate should be consistent with the size and uniformity of sections, so that the entire part is brought up to temperature as uniformly as possible. 加热的速率也应与截面的尺寸及均匀程度相协调，这样才能使整个零件尽可能均匀地加热。

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Normalizing and Spheroidizing 正火和球化

The process of normalizing consists of heating the steel about 50℉ to 100℉ (10℃~40℃) above the upper critical range and cooling in still air to room temperature. 正火处理包括先将钢加热到高于上临界区50℉到100℉(10℃~40℃)然后在静止的空气中冷却到室温。

This process is principally used with low- and medium-carbon steels as well as alloy steels to make the grain structure more uniform, to relieve internal stresses, or to achieve desired results in physical properties. Most commercial steels are normalized after being rolled or cast. 退火主要用于低碳钢、中碳钢及合金钢，使晶粒结构更均匀、释放内应力或获得所需的物理特性。大多数商业钢材在轧制或铸造后都要退火。

Spheroidizing is the process of producing a structure in which the cementite is in a spheroidal distribution. If steel is heated slowly to a temperature just below the critical range and held there for a prolonged period of time, this structure will be obtained. 球化是使渗碳体产生成类似球状分布结构的工艺。如果把钢缓慢加热到恰好低于临界温度并且保持较长一段时间，就能得到这种组织结构。

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The globular structure obtained gives improved machinability to the steel. This treatment is particularly useful for hypereutectoid steels that must be machined. 所获得的球状结构改善了钢的可切削性。此处理方法对必须机加工的过共析钢特别有用。

Surface Hardening 表面硬化 Carburizing The oldest known method of producing a hard surface on steel is case hardening or carburizing. Iron at temperatures close to and above its critical temperature has an affinity for carbon. 渗碳

最早的硬化钢表面的方法是表面淬火或渗碳。铁在靠近并高于其临界温度时对碳具有亲合力。

The carbon is absorbed into the metal to form a solid solution with iron and converts the outer surface into high-carbon steel. The carbon is gradually diffused to the interior of the part. The depth of the case depends on the time and temperature of the treatment. 碳被吸收进金属与铁形成固溶体使外表面转变成高碳钢。碳逐渐扩散到零件内

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部。渗碳层的深度取决于热处理的时间和温度。

Pack carburizing consists of placing the parts to be treated in a closed container with some carbonaceous material such as charcoal or coke. It is a long process and used to produce fairly thick cases of from 0.03 to 0.16 in.(0.76~4.06mm) in depth. 固体渗碳的方法是将要处理的零件与木炭或焦炭这些含碳的材料一起放入密闭容器。这是一个较长的过程，用于产生深度为0.03到0.16 英寸(0.76~4.06mm)这么厚的硬化层。

Steel for carburizing is usually a low-carbon steel of about 0.15% carbon that would not in itself responds appreciably to heat treatment. In the course of the process the outer layer is converted into high-carbon steel with a content ranging from 0.9% to 1.2% carbon. 用于渗碳的一般是含碳量约为0.15%、本身不太适合热处理的低碳钢。在处理过程中外层转化为含碳量从0.9%到1.2%的高碳钢。

A steel with varying carbon content and, consequently, different critical temperatures requires a special heat treatment. 含碳量变化的钢具有不同的临界温度，因此需要特殊的热处理。

Because there is some grain growth in the steel during the prolonged carburizing treatment, the work should be heated to the critical temperature of the core and then cooled, thus refining the core structure. The steel

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should then be reheated to a point above the transformation range of the case and quenched to produce a hard, fine structure. 由于在较长的渗碳过程中钢内部会有些晶粒生长，所以工件应该加热到核心部分的临界温度再冷却以细化核心部分的组织结构。然后重新加热到高于外层转变温度再淬火以生成坚硬、细致的组织结构。

The lower heat-treating temperature of the case results from the fact that hypereutectoid steels are normally austenitized for hardening just above the lower critical point. A third tempering treatment may be used to reduce strains. 由于恰好高于低临界温度通常使过共析钢奥氏体化而硬化，所以对外层采用较低的热处理温度。第三次回火处理可用于减少应变。

Carbonitriding Carbonitriding, sometimes known as dry cyaniding or nicarbing, is a case-hardening process in which the steel is held at a temperature above the critical range in a gaseous atmosphere from which it absorbs carbon and nitrogen. 碳氮共渗

碳氮共渗，有时也称为干法氰化或渗碳氮化，是一种表面硬化工艺。通过把钢放在高于临界温度的气体中，让它吸收碳和氮。

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Any carbon-rich gas with ammonia can be used. The wear-resistant case produced ranges from 0.003 to 0.030 inch(0.08~ 0.76mm) in thickness. An advantage of carbonitriding is that the hardenability of the case is significantly increased when nitrogen is added, permitting the use of low-cost steels. 可以使用任何富碳气体加氨气，能生成厚度从0.003到0.030英寸(0.08~ 0.76mm)的耐磨外层。碳氮共渗的优点之一是加入氮后外层的淬透性极大增加，为使用低价钢提供条件。

Cyaniding Cyaniding, or liquid carbonitriding as it is sometimes called, is also a process that combines the absorption of carbon and nitrogen to obtain surface hardness in low-carbon steels that do not respond to ordinary heat treatment. 氰化

氰化，有时称为液体碳氮共渗，也是一种结合了吸收碳和氮来获得表面硬度的工艺，它主要用于不适合通常热处理的低碳钢。

The part to be case hardened is immersed in a bath of fused sodium cyanide salts at a temperature slightly above the Ac1 range, the duration of soaking depending on the depth of the case. The part is then quenched in water or oil to obtain a hard surface.

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需表面硬化的零件浸没在略高于Ac1温度熔化的氰化钠盐溶液中，浸泡的持续时间取决于硬化层的深度。然后将零件在水或油中淬火。

Case depths of 0.005 to 0.015in. (0.13~0.38mm) may be readily obtained by this process. Cyaniding is used principally for the treatment of small parts. 通过这样处理可以容易地获得0.005到0.015英寸(0.13~0.38mm)的硬化深度。氰化主要用于处理小零件。

Nitriding Nitriding is somewhat similar to ordinary case hardening, but it uses a different material and treatment to create the hard surface constituents. 渗氮

渗氮有些类似普通表面硬化，但它采用不同的材料和处理方法来产生坚硬表面成分。

In this process the metal is heated to a temperature of around 950℉(510℃) and held there for a period of time in contact with ammonia gas. Nitrogen from the gas is introduced into the steel, forming very hard nitrides that are finely dispersed through the surface metal. 这种工艺中金属加热到约950℉(510℃)，然后与氨气接触一段时间。氨气中的氮进入钢内，形成细微分布于金属表面又十分坚固的氮化物。

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Nitrogen has greater hardening ability with certain elements than with others, hence, special nitriding alloy steels have been developed. 氮与某些元素的硬化能力比其它元素大，因此开发了专用的渗氮合金钢。 Aluminum in the range of 1% to 1.5% has proved to be especially suitable in steel, in that it combines with the gas to form a very stable and hard constituent. The temperature of heating ranges from 925℉ to 1,050℉(495℃~565℃).

在钢中含铝1%到1.5%被证明特别合适，它能与氨气结合形成很稳定坚固的成分。其加热温度范围为925℉到1,050℉ (495℃~565℃)。

Liquid nitriding utilizes molten cyanide salts and, as in gas nitriding, the temperature is held below the transformation range. Liquid nitriding adds more nitrogen and less carbon than either cyaniding or carburizing in cyanide baths. 液体渗氮利用熔化的氰化物盐，就像气体渗氮，温度保持在低于转化范围内。液体渗氮时在氰化物溶液中加入比氰化及渗碳都较多的氮和较少的碳。

Case thickness of 0.001 to 0.012in.(0.03~0.30mm) is obtained, whereas for gas nitriding the case may be as thick as 0.025 in.(0.64mm). In general the uses of the two-nitriding processes are similar. 液体渗氮可以获得厚度为0.001到0.012英寸 (0.03~0.30mm)的硬化层，然而气体渗氮则能获得厚0.025英寸(0.64mm)的硬化层。一般而言两种渗氮方法的用途是类

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似的。

Nitriding develops extreme hardness in the surface of steel. This hardness ranges from 900 to 1,100 Brinell, which is considerably higher than that obtained by ordinary case hardening. 渗氮在钢表面获得远远超出正常标准的硬度。其硬度范围为900到1,100布氏硬度，这远高于普通表面硬化所获得的硬度。

Nitriding steels, by virtue of their alloying content, are stronger than ordinary steels and respond readily to heat treatment. It is recommended that these steels be machined and heat-treated before nitriding, because there is no scale or further work necessary after this process. 由于渗氮钢的合金比例，它们比普通钢更强，也容易热处理。建议对这种钢在渗氮前先机加工和热处理，因为渗氮后没有剥落并不需要更多的加工。

Fortunately, the interior structure and properties are not affected appreciably by the nitriding treatment and, because no quenching is necessary, there is little tendency to warp, develop cracks, or change condition in any way. The surface effectively resists corrosive action of water, saltwater spray, alkalies, crude oil, and natural gas. 值得庆幸的是由于渗氮处理一点都不影响内部结构和性能，也无需淬火，所以几乎没有任何产生翘曲、裂缝及变化条件的趋势。这种表面能有效地抵御水、盐雾、碱、原油和天然气的腐蚀反应。

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Casting is a manufacturing process in which molten metal is poured or injected and allowed to solidify in a suitably shaped mold cavity. During or after cooling, the cast part is removed from the mold and then processed for delivery. 铸造是一种将熔化的金属倒入或注入合适的铸模腔并且在其中固化的制造工艺。在冷却期间或冷却后，把铸件从铸模中取出，然后进行交付。

Casting processes and cast-material technologies vary from simple to highly complex. Material and process selection depends on the part’s complexity and function, the product’s quality specifications, and the projected cost level. 铸造工艺和铸造材料技术从简单到高度复杂变化很大。材料和工艺的选择取决于零件的复杂性和功能、产品的质量要求以及成本预算水平。

Castings are parts that are made close to their final dimensions by a casting process. With a history dating back 6,000 years, the various casting processes are in a state of continuous refinement and evolution as technological advances are being made. 通过铸造加工，铸件可以做成很接近它们的最终尺寸。回溯6,000年历史，各种各样的铸造工艺就如同科技进步一样处于一个不断改进和发展的状态。

Sand Casting 砂型铸造

Sand casting is used to make large parts (typically iron, but also bronze,

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brass, aluminum). Molten metal is poured into a mold cavity formed out of sand (natural or synthetic). 砂型铸造用于制造大型零件(具有代表性是铁，除此之外还有青铜、黄铜和铝)。将熔化的金属倒入由型砂(天然的或人造的)做成铸模腔。

The processes of sand casting are discussed in this section, including patterns, sprues and runners, design considerations, and casting allowance. 本节讨论砂型铸造工艺，包括型模、浇注口、浇道、设计考虑因素及铸造余量。 The cavity in the sand is formed by using a pattern (an approximate duplicate of the real part), which are typically made out of wood, sometimes metal. The cavity is contained in an aggregate housed in a box called the flask. 砂型里的型腔是采用型模(真实零件的近似复制品)构成的，型模一般为木制，有时也用金属制造。型腔整个包含在一个被放入称为砂箱的箱子里的组合体内。

Core is a sand shape inserted into the mold to produce the internal features of the part such as holes or internal passages. Cores are placed in the cavity to form holes of the desired shapes. Core print is the region added to the pattern, core, or mold that is used to locate and support the core within the mold. 砂芯是插入铸模的砂型，用于生成诸如孔或内通道之类的内部特征。砂芯安放在型腔里形成所需形状的孔洞。砂芯座是加在型模、砂芯或铸模上的特定区域，用

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来在铸模内部定位和支撑砂芯。

A riser is an extra void created in the mold to contain excessive molten material. The purpose of this is to feed the molten metal to the mold cavity as the molten metal solidifies and shrinks, and thereby prevents voids in the main casting. 冒口是在铸模内部增加的额外空间，用于容纳过多的熔化金属。其目的是当熔化金属凝固和收缩时往型腔里补充熔化金属，从而防止在主铸件中产生孔隙。

In a two-part mold, which is typical of sand castings, the upper half, including the top half of the pattern, flask, and core is called cope and the lower half is called drag, as shown in Fig.3.1. The parting line or the parting surface is line or surface that separates the cope and drag. 在典型砂型铸造的两箱铸模中，上半部分(包括型模顶半部、砂箱和砂芯)称为上型箱，下半部分称为下型箱，见图3.1所示。分型线或分型面是分离上下型箱的线或面。

The drag is first filled partially with sand, and the core print, the cores, and the gating system are placed near the parting line. The cope is then assembled to the drag, and the sand is poured on the cope half, covering the pattern, core and the gating system. 首先往下型箱里部分地填入型砂和砂芯座、砂芯，并在靠近分型线处放置浇注系统。然后将上型箱与下型箱装配在一起，再把型砂倒入上型箱盖住型模、砂芯和

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浇注系统。

The sand is compacted by vibration and mechanical means. Next, the cope is removed from the drag, and the pattern is carefully removed. The object is to remove the pattern without breaking the mold cavity. 型砂通过振动和机械方法压实。然后从下型箱上撤掉上型箱，小心翼翼地取出型模。其目的是取出型模而不破坏型腔。

This is facilitated by designing a draft, a slight angular offset from the vertical to the vertical surfaces of the pattern. This is usually a minimum of 1.5mm(0.060in.), whichever is greater. The rougher the surface of the pattern, the more the draft to be provided. 通过设计拔模斜度—型模垂直相交表面的微小角度偏移量—来使取出型模变得容易。拔模斜度最小一般为1.5mm(0.060in.)，只能比此大。型模表面越粗糙，则拔模斜度应越大。

The molten material is poured into the pouring cup, which is part of the gating system that supplies the molten material to the mold cavity. 熔化的金属从浇注杯注入型腔，浇注杯是浇注系统向型腔提供熔化金属的部分。 The vertical part of the gating system connected to the pouring cup is the sprue, and the horizontal portion is called the runners and finally to the multiple points where it is introduced to the mold cavity called the gates.

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将浇注系统的垂直部分与浇注杯连接的是浇注口，浇注系统的水平部分称为浇道，最后到多点把熔化金属导入型腔的称为闸道。

Additionally there are extensions to the gating system called vents that provide the path for the built-up gases and the displaced air to vent to the atmosphere. 除此之外，还有称为排放口的浇注系统延长段，它为合成气体和置换空气排放到大气提供通道。

The cavity is usually made oversize to allow for the metal contraction as it cools down to room temperature. This is achieved by making the pattern oversize. To account for shrinking, the pattern must be made oversize by these factors on the average. These are linear factors and apply in each direction. 型腔通常大于所需尺寸以允许在金属冷却到室温时收缩。这通过把型模做得大于所需尺寸来达到。为解决收缩效应，一般而言型模做得比所需尺寸大，必须考虑线性因素并作用于各个方向。

These shrinkage allowances are only approximate, because the exact allowance is determined by the shape and size of the casting. In addition, different parts of the casting might require different shrinkage allowances. 收缩余量仅仅是近似的，因为准确的余量是由铸件的形状和尺寸决定的。另外，铸件的不同部分也可能需要不同的收缩余量。

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Sand castings generally have a rough surface sometimes with surface impurities, and surface variations. A machining (finish) allowance is made for this type of defect. 砂型铸件一般表面粗糙，有时还带有表面杂质和表面变异。对这类缺陷采用机加工(最后一道工序)的余量。

In general, typical stages of sand casting operation include (as shown in Fig.3.2): 1. Patterns are made. These will be the shape used to form the cavity in the sand. 一般而言，砂型铸造作业的典型阶段包括(如图3.2所示)： 1. 制作型模。做成用于在型砂中形成型腔的形状。

2. Cores may also be made at this time. These cores are made of bonded sand that will be broken out of the cast part after it is complete. 3. Sand is mulled (mixed) thoroughly with additives such as bentonite to increase bonding and overall strength. 2. 同时还要制作砂芯。这些砂芯用粘结砂做成，等铸件完成后将被打碎取出。 3. 型砂与膨润土之类的添加剂充分地混合以增强连接及整体强度。

4. Sand is formed about the patterns, and gates, runners, risers, vents

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and pouring cups are added as needed. A compaction stage is typically used to ensure good coverage and solid molds. 4. 型砂在型模周围成形，并根据需要安放闸道、浇道、冒口、排放口和浇注杯等。通常要采取压紧步骤来保证良好的覆盖和坚固的铸型。

Cores may also be added to make concave or internal features for the cast part. Alignment pins may also be used for mating the molds later. Chills may be added to cool large masses faster. 安放砂芯来制成铸件的凹形结构或内部特征。为了以后铸模匹配还要用到定位销。对大质量铸件可能需要加入冷却物来使其较快冷却。

5. The patterns are removed, and the molds may be put through a baking stage to increase strength. 6. Mold halves are mated and prepared for pouring metal. 5. 取走型模，将铸模烘焙以增加强度。 6. 匹配上下铸模，做好浇铸金属的准备。

7. Metal is preheated in a furnace or crucible until is above the liquidus temperature in a suitable range (we don’t want the metal solidifying before the pour is complete). The exact temperature may be closely controlled depending upon the application. 7. 金属在熔炉或坩埚中预热到高于液化温度的一个合适范围内(不希望金属在

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浇铸完成前凝固)。确切的温度要根据应用场合严格控制。

Degassing, and other treatment processes may be done at this time, such as removal of impurities (i.e. slag). Some portion of this metal may be remelted scrap from previously cast parts—10% is reasonable. 在此期间还要进行排气和其它处理步骤，例如去除杂质(即熔渣)。可以加入一定量原先是这种金属铸件的废料再融化—10%是适当的。

8. The metal is poured slowly, but continuously into the mold until the mold is full. 9. As the molten metal cools (minutes to days), the metal will shrink and the volume will decrease. During this time molten metal may backflow from the molten risers to feed the part and maintain the same shape. 8. 将金属缓慢而连续地注满型模。

9. 随着熔化金属的冷却(几分钟到几天)，金属收缩体积减小。在此期间熔化金属可能从冒口回流供给零件以保持其形状不变。

10. Once the part starts to solidify small dendrites of solid material form in the part. During this time metal properties are being determined, and internal stresses are being generated. If a part is allowed to cool slowly enough at a constant rate then the final part will be relatively homogenous and stress free.

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10. 在零件开始凝固其内部形成固态金属的小型树枝状结晶期间金属性能被确定，同时也产生了内应力。如果零件以恒定速率冷却得足够缓慢，最终零件将相对均质并释放内应力。

11. Once the part has completely solidified below the eutectic point it may be removed with no concern for final metal properties. At this point the sand is simply broken up, and the part removed. At this point the surface will have a quantity of sand adhering to the surface, and solid cores inside. 11. 一旦零件在共析点以下完全凝固，可以不考虑金属的最后性能而将其取出。这时可以简单地打碎砂型并取出零件，但零件表面会有大量型砂粘附着，内部还有实心的砂芯。

12. A bulk of the remaining sand and cores can be removed by mechanically striking the part. Other options are to use a vibrating table, sand/shot blaster, hand labor, etc. 12.大量的剩余型砂和砂芯要通过机械敲击零件来去除。其它的选择还有采用振动台、喷砂/喷丸机、手工作业等等。

13. The final part is cut off the runner gate system, and is near final shape using cutters, torches, etc. Grinding operations are used to remove any remaining bulk. 14. The part is taken down to final shape using machining operations. And cleaning operations may be used to remove oxides, etc.

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13. 最后零件要用刀具、喷枪等切掉浇道闸道系统，这样就接近最终形状了。再用磨削作业去除多余的部分。

14. 通过机加工将零件切削到最终形状。可能还要用清洗作业去除氧化物等。 Investment casting 熔模铸造

Investment casting is also known as the lost wax process. This process is one of the oldest manufacturing processes. The Egyptians used it in the time of the Pharaohs to make gold jewelry (hence the name Investment) some 5,000 years ago. 熔模铸造也称为失蜡加工。这是最古老的制造工艺之一。大约在5,000年前的法老王时代，埃及人就用它制造黄金饰品(因此而得名投资)。

Intricate shapes can be made with high accuracy. In addition, metals that are hard to machine or fabricate are good candidates for this process. It can be used to make parts that cannot be produced by normal manufacturing techniques, such as turbine blades that have complex shapes, or airplane parts that have to withstand high temperatures. 复杂的形状能被高精度地制造。另外较难机加工或制作的金属都能用此工艺。它还能用于生产一般制造技术无法生产的零件，例如有复杂形状的涡轮叶片或必须耐得住高温的飞机零件。

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The mold is made by making a pattern using wax or some other material that can be melted away. This wax pattern is dipped in refractory slurry, which coats the wax pattern and forms a skin. This is dried and the process of dipping in the slurry and drying is repeated until a robust thickness is achieved. 制作铸型的型模采用石蜡或其它一些能被融化掉的材料做成。石蜡型模浸泡在耐热浆里，让它覆盖型模并形成外壳，然后使其变干。重复这个浸泡、变干的过程直至获得足够的厚度。

After this, the entire pattern is placed in an oven and the wax is melted away. This leads to a mold that can be filled with the molten metal. Because the mold is formed around a one-piece pattern (which does not have to be pulled out from the mold as in a traditional sand casting process), very intricate parts and undercuts can be made. 完成后把整个型模放在烤箱里融化石蜡。这样就做成了能填充熔化金属的铸型。由于这种铸型是环绕整块型模形成的(无需像传统的砂型铸造工艺那样拔模)，能制作十分复杂的零件和浮雕。

The wax pattern itself is made by duplicating using a stereo lithography or similar model—which has been fabricated using a computer solid model master. 石蜡型模本身能用立体制版或类似的模型复制—这可以采用计算机立体模型原

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版制作。

The materials used for the slurry are a mixture of plaster, a binder and powdered silica, a refractory, for low temperature melts. For higher temperature melts, sillimanite or alumina-silicate is used as a refractory, and silica is used as a binder. 对较低熔化温度而言，用于耐热浆的材料是石膏作粘合剂和用粉末状硅石作耐温材料的混合物。对较高熔化温度而言，则采用硅线石或氧化铝硅酸盐作耐温材料、无水硅酸作粘合剂。

Depending on the fineness of the finish desired additional coatings of sillimanite and ethyl silicate may be applied. The mold thus produced can be used directly for light castings, or be reinforced by placing it in a larger container and reinforcing it more slurry. 根据最后所需光洁度也可采用硅线石和乙烷基硅酸盐。这样生成的铸模可直接用于薄壁铸件或通过将其放在较大容器内用更多耐热浆加强。

Just before the pour, the mold is pre-heated to about 1,000℃(1,832℉) to remove any residues of wax, harden the binder. The pour in the pre-heated mold also ensures that the mold will fill completely. 在正要浇铸之前，将型模预热到约1,000℃(1,832℉)以去除剩余石蜡、硬化粘合剂。在预热的型模中浇铸也能保证型模完全充满。

Pouring can be done using gravity, pressure or vacuum conditions.

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第五篇：机械专业毕业求职信

尊敬的老师：

您好!

我叫XXX，就读北京工商大学，将于2010年6月机械工程及其自动化专业毕业，盼望老师能给一位渴望成长，渴望成功，更渴望成才的学子一片土壤。

出生在美丽的大草原上，虽然区域教育并不发达，我通过勤奋和努力，最终把一篇叫做《不过一片栖息地》的文章丢印上了高中60年校庆的纪念册上，只身来到京读书。在此我得到了从身体到心理成熟、从外在到内在的全面发展、从偏到全的自我认识。无论是在学校学习中取得优异的成绩，还是在校外实习兼职的小有收红，都使我不丰满臂膀更加健壮。

进入大学幸运的选到了自己喜爱的专业——机械，四年的学习令我更加喜欢上了机械。无论从工程制图的手绘到autoCAD的机绘，再到solidworks和proe的三维建模，我都有叫深入的涉猎，喜欢这种亲自制作出来的三维玩意。同时，刻苦朴素，和家中协商，投入自己的奖学金，买一部电脑协助学习。现在能应用机械类相关软件外，能非常熟练的运用office软件，会用photoshop做图像的处理，以及其他的简单视频处理刻录软件。我许多业余爱好，我们全家都是乒乓球爱好者，我还爱好网球，喜爱唱歌，喜欢旅游，登临郭五岳之首的泰山，喜欢看书，对中国古今名著和金庸的小说情有独钟。

在学校期间，在不忘记学习的前提下，取得良好成绩的同时，积极参加了许多社团社会活动，从中锻炼自己，让自己从多方面提高自己。其中也取得良好的成绩，获得各种演讲、主持、征文等奖励。

在丰富的学校生活中担任了很多角色，担任班级干部，由我亲手整理和编写的申请材料，使得班级取得了北京市优秀班集体;有幸进入北京奥运城市志愿者的行列，在认真负责紧张充实的工作中，培养了自己的风险精神;出任过社团组织委员和运动会领队队长，组织活动和协调团队，取得了比赛的优异成绩的同时，也增加了更宝贵的团队意识;在宿舍我也以身作则，常常主动收拾整理，在我的带领下，使得宿舍连续被评为标兵宿舍。

在校外，积极参加和争取实习和兼职，在红粉佳人影楼担任过代理店长，得到领导的称赞，取得了额外的推销提成;也去过现代汽车公司参观实习，深刻的了解到现代汽车厂的生产流程以及企业文化，同时在学校报告总结中非常系统的分析和概括了贵公司整体情况;还独立在车站等地区，买卖过北京地图，使得更加了解北京，同时客服自己腼腆心理和转向毛病，最后取得巨大胜利;于今年暑假，独身留在北京，多方主动去了解现在就业市场，获得许多就业第一手资料和宝贵的社会经验。

不错，此刻，我只是一个普通高校的普通学校，我没能有幸成为名牌大学学生，但我始终不会放弃追赶名牌、成为一流的决心，无论路有多么坎坷和艰辛，总有站在前列能者，相信那些人中会有一个人，是我!请贵公司给一个渴望得到成才，更渴望得到承认的一名学生一次机会。

此致

敬礼