Unit 7 Lathes 机电专业英语 图文课件
机械工程专业英语课件--L12
tracing and duplicating lathes, (4) single-spindle 转塔车床没有尾架和丝杠，而在尾架的位置上装有一 automatic lathes, (5) multi-spindle automatic lathes, (6) 个装有一个能纵向移动多任务位主切削刀架（如：转 shapers and planers, (7) boring machines. 塔刀架、回轮刀架），另外还具有辅助刀架（如：前、 后刀架），能完成卧式车床上的各种加工工序。是一 本质上，使用单刃刀具切削的机床包括： 种多刀、多任务位加工的高效机床，加工效率比卧式 (1)普通车床；(2)转塔车床；(3)仿形车床； 车床高2~3倍。转塔车床的调整需花费较多时间，适合 于成批生产。 (4)单轴自动车床；(5)多轴自动车床；(6) 此外，转塔车床刀架的纵横向进给设有撞停定程 牛头刨床和龙门刨床；(7)镗床。 装置，可自动控制铬镍钢件尺寸，保证成批工件尺寸 课文分析 的一致性，能自动实现机床的变速预选、进给量改变
主轴箱：电机---齿轮变速---主轴
尾座：锥孔+顶尖 导轨：平、燕尾 刀架：中拖板（流板箱）作横向进给，大拖板作纵向移动 丝杠：加工螺纹
光杠：切削外圆、端面
预备知识
机械工程专业英语
二、词汇
Lesson 24 Lathes
engine lathe 普通车床 turrent lathe 转塔车床 tracing and duplicating lathe 仿形车床 single-spindle automatic lathe 单轴自动车床 multi-spindle automatic lathe 多轴自动车床 shape 牛头刨床 cylindrical grinder 外圆磨床 planer 龙门刨床 centreless grinder 无心磨床 surface grinder 平面磨床 boring machine 镗床 drilling machine 钻床 milling machine 铣床 broaching machine 拉床 sawing machine 锯床 gear-cutting machine 齿轮加工机床
UNIT-7-fasteners-and-springs-(3)PPT课件
External Thread
Thread angle
Internal Thread
2021/1/16Root
Root Cre-机st械工程专业英语教程》
Crest
25
THREAD TERMINOLOGY
Major diameter Minor diameter
The largest diameter on an internal or external thread. The smallest diameter on an internal or external thread.
- keys
key
- pin
Terminology
• fastener [‘fɑ:snə] n. 紧固件，联接件 • acceptability [ək,septə‘biliti] n. 可接受性,接受,合格,满意 • disassembly [,disə‘sembli] n. 分解,拆卸，拆除，解体
一个紧固件的失效或松脱可能会带来像车门嘎嘎响这类
小麻烦，也可能造成像车轮脱落这种严重的后果。
Such possibilities must be taken into account in
the selection of the type of fastener for the
specific application.
因此，在为一个特定的用途选择紧固件时，应该考
虑到
上述各种可能性。
Springs are mechanical members which are designed to give a relatively large amount of elastic deflection under the action of an externally applied load.
机械专业英语图解教程
diestock
differential gear
disc brake drilling machine expanded metal
dowel
drawing board
drift
drill
dog clutch plate clutch clutch
faceplate
feeler gauge
90 0 dial gauge
常用工具 机械零部件和机构
abrasive disc
adjustable spanner
Allen key
angle iron (plate)
anivil
arbor
ball bearing
bandsaw
bifurcated rivet
beam compass belt
brace
breast drill
washer
worm
worm wheel
worm gear
water-cooled engine
workbench
grinding machine
gear train
spur gear
spiral(helical) gear
gouge
gear cutter
grub screw
knob gudgeon pin shaft
piston ring 活塞环
poppet valve 气门 提升阀
power hammer 气锤
press 冲床 压力机
80 120
40
160
/m3 200
pressure gauge 压力表
propeller 螺旋桨
propeller shaft 传动轴
Unit-7-Lathes-机电专业英语-图文课件
machines used in production and maintenance shops all over the world. Sizes range from small bench models to huge heavy duty pieces of equipment. Many of the larger lathes are equipped with auxiliary parts which are not commonly available in ordinary shops，such as automatic stops for the carriage.
Text & Translation
The first screw machines were designed to feed bar stock and wire used in making small screw parts. At present，however， the turret lathe is frequently used with a collet attachment，and the automatic screw machine can be equipped with a chuck to hold castings.
Text & Translation
In the single spindle automatic screw machine，a specific length of stock is automatically fed through the spindle to a machining area. At this point，the turret and cross slide move into position and automatically perform whatever operations are required. After the machined piece is cut off，stock is again fed into the machining area and the entire cycle is repeated.
机械专业英语完整7PPT课件
可编辑课件
3
Murphy’s Law: If any material can fail, it will.
Laws of materials applications
(1) All materials are unstable.
Materials are the reality in a design.
如果现存的材料不具备必要的性能，或者只有新材料 开发出来才能制造，在设计仿真阶段就必须改动这些 材料的技术要求。在设计中材料是现实的。
可编辑课件
13
Paragraph 5
Figure 1 illustrates a simple schematic representation of a design process that includes design implementation.
除非开发出新的材料，否则由于材料不具有必要的性 能而不能实现的设计只能是一个永远不能成为现实的 概念。
可编辑课件
11
Prior to a fabrication step, materials specifications must be made depending upon the design requirements.
计算机辅助设计现在已用于设计过程，各种设计和设 计思想能被检验和仿真。
可编辑课件
10
Paragraph 4:
Even in the early design cycle, it is useful to have some concept of available materials.
即使在早期的设计循环中，具有一些材料的概念也是 有用的。
机电英语Unit 7
development project with a blank slate. A PDM system can help
mold designers find existing mold designs that are similar to the project at hand, which they can then easily adapt for new jobs,
Unit 7 Operational & Technical Management
Reading A
PDM System and Mold Design
Product Data Management (PDM) system, a computer-based system which electronically maintains the organizational data, promises mold makers efficient data management and helps them to save time, control costs and ensure quality. The following tips will help mold makers learn how PDM can meet
operational and technical management. Arrange them in the order of time and explain.
a. Read the articles on application of PDM system in mold design. b. Inspect offices and listen to mold designers’ advice on PDM system application. c. Observe and study the company’s production and operation. d. Hold meetings to discuss what innovative measures the company may take. e. Report to the board innovative measures to be taken.
机电专业英语ppt
Chapter One Lesson One
Mechanics Components
Gears
Spur and helical gears.
A gear having tooth elements that are straight and parallel to its axis is known as a spur gear. A spur pair can be used to connect parallel shafts only. Parallel shafts, however, can also be connected by gears of another type, and a spur gear can be mated with a gear of a different type (Fig. 1-1).
The thrust problem can be overcome by cutting two sets of opposed helical teeth on the same blank. Depending on the method of manufacture, the gear may be of the continuous-tooth herringbone variety or a double-helical gear with a space between the two halves to permit the cutting tool to run out. Doublehelical gears are well suited for the efficient transmission of power at high speeds.
机械机电车床行业PPT模板课件
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《机电专业英语》PPT课件
shaft [ʃɑ:ft] n. [C]轴；矿井;竖井 • valve [væ lv] n. n. [c]1. 阀,活门 2. 真空管，电子
管 • innumerable [i‘nju:mərəbl] adj.无数的;数不清的
他的价值观念似乎陈旧了。 • immense [i mens] adj.极大的，巨大的
例句：They made an immense improvement in English.
在E英nd语方面他们取得了巨大的进步To。pic Above Next
centrifugal [sen‘trifjugəl] adj.离心的
例句：In as much as the debtor has no property , I abandoned the claim.
因为债务人无财产,我放弃了债务。 debtor [‘detə] n. 借方，债务人
End
Topic Above Next
They bought in as much food as would last the winter.
End
Topic Above 汉 Next
When “feedback” is applied to the process
by which a large digital computer runs at th
e immense speed through a long series of su
任何对党的信仰的偏离被视作背叛。 • betrayal [bi'treiəl] n. 1. 背叛;密告;泄密2. 引诱 • spinning [spini] adj.旋转的 n.纺线，纺纱
机电一体化专业英语PPT
Unit 1
Passage A
Center Drills (中心钻) Center drills are stiff, stubby little drills used to start holes in the end of work-piece. If you try to drill a hole in a work-piece without using a center drill，you will find that the drill will most likely wobble off center and not drill straight into the work-piece. Standard drilling practice is to first make a facing cut on the end of the work-piece, then drill a starter hole using a center drill and then drill the hole to the required depth with a standard drill.
机械工程专业英语Unit 7
实际上对显微照片的分析显示这种切屑瘤受到静摩擦力抑制直至它变得大到作用在它上面的外力使其移动一些留在机加工表面上而另一些延伸到切屑的背面见图73c
Unit 7 Metal Cutting 金属切割
➢ importance of metal cutting 金属切割的重要性 ➢ Introduction of a typical cutting tool 典型切割刀具的介绍 ➢ Chip Formation 切屑形成 ➢ Shear zone 剪切区 ➢ Cutting Tool Materials 切割刀具材料 ➢ Surface Finish 表面光洁度 ➢ Cutting Fluids 切割液
Chip formation in metal cutting could be broadly categorized into
three types (Fig.7.3). 金属切削中的切屑形成可以宽泛地分成三个类型(图
7.3)。
积屑瘤
❖ Discontinuous chip 间断切屑 ❖ Continuous chip 连续切屑 ❖ Continuous chip with BUE (Built up edge) 带切屑瘤的连续切屑
❖ In USA, more than $100 billions are spent annually on machining and related operations. 在美国，每年花在机加工及其相关作业上的 费用都多于千亿美元。
Unit-9-Machining-Center-机电专业英语-图文课件
Text & Translation
Two new trends are observed in the development of machining centers. One is the growing interest in smaller，more compact machining centers and the other is the emphasis on extended shift or even unmanned operations. Modern machining centers have contributed significantly to improved productivity in many companies. They have eliminated the time lost in moving workpieces from machine to machine and the time needed for workpiece loading and unloading for separate operations. In addition，they have minimized the time lost in changing tools，carrying out gauging operations，and aligning workpieces on the machine.
Text & Translation
加工中心有两个发展趋势：一是更小、更紧凑 的加工中心的兴起；二是对扩展轴或无人操作 的重视。现代的加工中心对很多公司提高生产 率有着重要的作用，节省了把工件从一台机床 移向另一台机床与对工件的单个加工所需的装 卸时间。此外，更换刀具、测量和工件定位的 时间也缩短至最低限度。
机电专业英语第Unit PPT课件
• The open—loop control system does not provide positioning feedback to the control unit.
• The closed—loop control system is very accurate. It has an automatic compensative function for error, since the feedback device indicates the error and the control makes the necessary adjustments to bring the slide back to the position. They apply AC, DC or hydraulic servomotors.
第5页/共42页
• Text • 4. Tool changers— In a common machining, several different cutting
tools are used to produce a part. The tools must be replaced quickly for the next machining operation. For this reason, the majority of NC／CNC machine tools are equipped with automatic tool changers, such as magazines on machine center and turrets on turning centers. They allow tool changing without the intervention of the operator.
机电专业英语
机电专业英语 高职高专 ppt 课件
[3] The more carbon the steel contains and the quicker the cooling is， the harder it becomes． 钢的含碳量越高，冷速越快，钢就变得越硬。 [4] ...because the alloying elements make them tougher，stronger or harder than carbon stainless steels． 因为合金元素能提高钢的韧性，强度和硬度（与碳钢比较）。 有些合金元素能提高钢的耐腐蚀性，这种钢称为不锈钢。 句中的“make”和“cause”均为及物动词，它们的宾语分别为 “them”和“steel”。作为宾语“them”的补足语是形容比较 级“tougher，stronger or harder”，而宾语“steel”的补足 语是不定式短语“to resist corrosion”。“stainless steels” 作主语“such steel”的补充语。
机电专业英语 高职高专 ppt 课件
2．Alloy steels (1) Special alloy steel，such as nickel， chromium steel． (2) High-speed steel also known as self-hardening steel．
机电专业英语 高职高专 ppt 课件
书名：机电专业英语 ISBN： 978-7-111-34794-1 作者：周美蓉 出版社：机械工业出版社 本书配有电子课件
机电专业英语 高职高专 ppt 课件
Part Ⅱ Machining Operation
Unit Unit Unit Unit Unit Unit 4 5 6 7 8 9
毕业设计机电专业英语文章
数控车床及车削加工介绍（中英文对照）1 LathesLathes are machine tools designed primarily to do turning, facing and boring, Very little turning is done on other types of machine tools, and none can do it with equal facility. Because lathes also can do drilling and reaming, their versatility permits several operations to be done with a single setup of the work piece. Consequently, more lathes of various types are used in manufacturing than any other machine tool.The essential components of a lathe are the bed, headstock assembly, tailstock assembly, and the leads crew and feed rod.The bed is the backbone of a lathe. It usually is made of well normalized or aged gray or nodular cast iron and provides s heavy, rigid frame on which all the other basic components are mounted. Two sets of parallel, longitudinal ways, inner and outer, are contained on the bed, usually on the upper side. Some makers use an inverted V-shape for all four ways, whereas others utilize one inverted V and one flat way in one or both sets, They are precision-machined to assure accuracy of alignment. On most modern lathes the way are surface-hardened to resist wear and abrasion, but precaution should be taken in operating a lathe to assure that the ways are not damaged. Any inaccuracy in them usually means that the accuracy of the entire lathe is destroyed.The headstock is mounted in a foxed position on the inner ways, usually at the left end of the bed. It provides a powered means of rotating the word at various speeds . 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. Most lathes provide from 8 to 18 speeds, usually in a geometric ratio, and on modern lathes all the speeds can be obtained merely by moving from two to four levers. An increasing trend is to provide a continuously variable speed range through electrical or mechanical drives.Because the accuracy of a lathe is greatly dependent on the spindle, it is of heavy construction and mounted in heavy bearings, usually preloaded tapered roller or ball types. The spindle has a hole extending through its length, through which long bar stock can be fed. The size of maximum size of bar stock that can be machined when the material must be fed through spindle.The tailsticd assembly consists, essentially, of three parts. A lower casting fits on the inner ways of the bed and can slide longitudinally thereon, with a means for clamping the entire assembly in any desired location, An upper casting fits on the lower one and can be moved transversely upon it, on some type of keyed ways, to permit aligning the assembly is the tailstock quill. This is a hollow steel cylinder, usually about 51 to 76mm(2to 3 inches) in diameter, that can be moved several inches longitudinally in and out of the upper casting by means of a hand wheel and screw.The size of a lathe is designated by two dimensions. The first is known as the swing. This is the maximum diameter of work that can be rotated on a lathe. It is approximately twice the distance between the line connecting the lathe centers and the nearest point on the ways, The second size dimension is the maximum distance between centers. The swing thus indicates the maximum work piece diameter that can be turned in the lathe, while the distance between centers indicates the maximum length of work piece that can be mounted between centers.Engine lathes are the type most frequently used in manufacturing. They are heavy-duty machine tools with all the components described previously and have power drive for all tool movements except on the compound rest. They commonly range in size from 305 to 610 mm(12 to 24 inches)swing and from 610 to 1219 mm(24 to 48 inches) center distances, but swings up to 1270 mm(50 inches) and center distances up to 3658mm(12 feet) are not uncommon. Most have chip pans and a built-in coolant circulating system. Smaller engine lathes-with swings usually not over 330 mm (13 inches ) –also are available in bench type, designed for the bed to be mounted on a bench on a bench or cabinet.Although engine lathes are versatile and very useful, because of the time required for changing and setting tools and for making measurements on the work piece, thy are not suitable for quantity production. Often the actual chip-production tine is less than 30% of the total cycle time. In addition, a skilled machinist is required for all the operations, and such persons are costly and often in short supply. However, much of the op erator’s time is consumed by simple, repetitious adjustments and in watching chips being made. Consequently, to reduce or eliminate the amount of skilled labor that is required, turret lathes, screw machines, and other types of semiautomatic and automatic lathes have been highly developed and are widely used in manufacturing.2 Numerical ControlOne of the most fundamental concepts in the area of advanced manufacturing technologies is numerical control (NC). Prior to the advent of NC, all machine tools ere manually operated and controlled. Among the many limitations associated with manual control machine tools, perhaps none is more prominent than the limitation of operator skills. With manual control, the quality of the product is directly related to and limited to the skills of the operator. Numerical control represents the first major step away from human control of machine tools.Numerical control means the control of machine tools and other manufacturing systems through the use of prerecorded, written symbolic instructions. Rather than operating a machine tool, an NC technician writes a program that issues operational instructions to the machine tool. For a machine tool to be numerically controlled, it must be interfaced with a device for accepting and decoding the programmed instructions, known as a reader.Numerical control was developed to overcome the limitation of human operators, and it has done so. Numerical control machines are more accurate than manually operated machines, they can produce parts more uniformly, they are faster, and the long-run tooling costs are lower. The development of NC led to the development of several other innovations inmanufacturing technology:Electrical discharge machining,Laser cutting,Electron beam welding.Numerical control has also made machine tools more versatile than their manually operated predecessors. An NC machine tool can automatically produce a wide of parts, each involving an assortment of widely varied and complex machining processes. Numerical control has allowed manufacturers to undertake the production of products that would not have been feasible from an economic perspective using manually controlled machine tolls and processes.Like so many advanced technologies, NC was born in the laboratories of the Massachusetts Institute of Technology. The concept of NC was developed in the early 1950s with funding provided by the U.S. Air Force. In its earliest stages, NC machines were able to made straight cuts efficiently and effectively.However, curved paths were a problem because the machine tool had to be programmed to undertake a series of horizontal and vertical steps to produce a curve. The shorter the straight lines making up the steps, the smoother is the curve, Each line segment in the steps had to be calculated.This problem led to the development in 1959 of the Automatically Programmed Tools (APT) language. This is a special programming language for NC that uses statements similar to English language to define the part geometry, describe the cutting tool configuration, and specify the necessary motions. The development of the APT language was a major step forward in the fur ther development from those used today. The machines had hardwired logic circuits. The instructional programs were written on punched paper, which was later to be replaced by magnetic plastic tape.A tape reader was used to interpret the instructions written on the tape for the machine. Together, all of this represented a giant step forward in the control of machine tools. However, there were a number of problems with NC at this point in its development.A major problem was the fragility of the punched paper tape medium. It was common for the paper tape containing the programmed instructions to break or tear during a machining process. This problem was exacerbated by the fact that each successive time a part was produced on a machine tool, the paper tape carrying the programmed instructions had to be rerun through the reader. If it was necessary to produce 100 copies of a given part, it was also necessary to run the paper tape through the reader 100 separate tines. Fragile paper tapes simply could not withstand the rigors of a shop floor environment and this kind of repeated use.This led to the development of a special magnetic plastic tape. Whereas the paper carried the programmed instructions as a series of holes punched in the tape, the plastic tape carried the instructions as a series of magnetic dots. The plastic tape was much stronger than the paper tape, which solved the problem of frequent tearing and breakage. However, it still left two other problems.The most important of these was that it was difficult or impossible to change the instructions entered on the tape. To made even the most minor adjustments in a program of instructions, it was necessary to interrupt machining operations and make a new tape. It was also still necessary to run the tape through the reader as many times as there were parts to be produced. Fortunately, computer technology became a reality and soon solved the problems of NC associated with punched paper and plastic tape.The development of a concept known as direct numerical control (DNC) solved the paper and plastic tape problems associated with numerical control by simply eliminating tape as the medium for carrying the programmed instructions. In direct numerical control, machine tools are tied, via a data transmission link, to a host computer. Programs for operating the machine tools are stored in the host computer and fed to the machine tool an needed via the data transmission linkage. Direct numerical control represented a major step forward over punched tape and plastic tape. However, it is subject to the same limitations as all technologies that depend on a host computer. When the host computer goesdown, the machine tools also experience downtime. This problem led to the development of computer numerical control.3 TurningThe engine lathe, one of the oldest metal removal machines, has a number of useful and highly desirable attributes. Today these lathes are used primarily in small shops where smaller quantities rather than large production runs are encountered.The engine lathe has been replaced in today’s production shops by a wide variety of automatic lathes such as automatic of single-point tooling for maximum metal removal, and the use of form tools for finish on a par with the fastest processing equipment on the scene today.Tolerances for the engine lathe depend primarily on the skill of the operator. The design engineer must be careful in using tolerances of an experimental part that has been produced on the engine lathe by a skilled operator. In redesigning an experimental part for production, economical tolerances should be used.Turret Lathes Production machining equipment must be evaluated now, more than ever before, this criterion for establishing the production qualification of a specific method, the turret lathe merits a high rating.In designing for low quantities such as 100 or 200 parts, it is most economical to use the turret lathe. In achieving the optimum tolerances possible on the turrets lathe, the designer should strive for a minimum of operations.Automatic Screw Machines Generally, automatic screw machines fall into several categories; single-spindle automatics, multiple-spindle automatics and automatic chucking machines. Originally designed for rapid, automatic production of screws and similar threaded parts, the automatic screw machine has long since exceeded the confines of this narrow field, and today plays a vital role in the mass production of a variety of precision parts. Quantities play an important part in the economy of theparts machined on the automatic screw machine. Quantities less than on the automatic screw machine. The cost of the parts machined can be reduced if the minimum economical lot size is calculated and the proper machine is selected for these quantities.Automatic Tracer Lathes Since surface roughness depends greatly on material turned, tooling , and feeds and speeds employed, minimum tolerances that can be held on automatic tracer lathes are not necessarily the most economical tolerances.In some cases, tolerances of 0.05mm are held in continuous production using but one cut . groove width can be held to 0.125mm on some parts. Bores and single-point finishes can be held to 0.0125mm. Onhigh-production runs where maximum output is desirable, a minimum tolerance of 0.125mm is economical on both diameter and length of turn.中文译文1.车床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。
机械加工-机械制造-Lesson 23 Lathes
《机械工程专业英语教程》
4
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《机械工程专业英语教程》
• Chuck
• A clamp that holds a tool or the material being worked in a machine such as a lathe.
• 卡盘：在诸如车床等机床上用来夹持刀具或工件的装置
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《机械工程专业英语教程》
• Collet 弹簧夹头
• Machining center 加工中心
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《机械工程专业英语教程》
Text tour
Engine lathes, of course, are general-purpose machines used in production and maintenance shops all over the world. Sizes range from small bench models to huge heavy duty pieces of equipment. Many of the larger lathes come equipped with attachments not commonly found in the ordinary shop, such as automatic stops for the carriage.
当前，许多技术更为先进的车床叫做加工中心。因为，它 们除了完成常规的车削工作之外，还可以完成某些铣削、 钻削工作。加工中心基本上可以认为是转塔车床和铣床的 组合体。有时，制造厂商为了增加机床的多用性，还会增 加一些其它的性能。
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2020/9/7
《机械工程专业英语教程》
Lesson 23 Lathes车床 机械专业专业英语教学用书
Lathes are machine tools designed primarily to do turning, facing, and boring（车外圆、车端面和钻孔）. Very little turning is done on other types of machine tools, and none can do it with equal facility（灵巧，设 备）. Because lathes also can do drilling and reaming （铰孔）, their versatility permits several operations to be done with a single setup（一次安装）of the workpiece. Consequently, more lathes of various types are used in manufacturing than any other machine tool.
Lesson 23 Lathes车床
Because the accuracy of a lathe is greatly dependent on the spindle（主轴）, it is of heavy construction and mounted in heavy bearings, usually preloaded tapered rolled（圆锥滚 子轴承）or ball types. The spindle has a hole extending through its length, through which long bar stock（棒料） can be fed. 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.
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Text & Translation
3.Turret Lathes When machining a complex workpiece on a general purpose
lathe，a great deal of time will be spent in changing or adjusting the tools needed. ［2］One of the first adaptations of the engine lathe which made it more suitable to mass production was the addition of multi tool turret in place of the tailstock. Although most turrets have six stations，some have as many as eight. High production turret lathes are very complicated with many power accessories. The principal feature of all turret lathes， however，is that they can perform a consecutive serial of operations in proper sequence. Once the tools have been set and adjusted，little skill is required to turn out duplicate parts.
New Words & Expressions
forging ['fɔ:dʒiŋ] n. 锻造；锻件 bar stock 棒料 collet ['kɔlit] n. 夹头 attachment [ə'tætʃmənt] n. 附件 spindle ['spindl] n. 主轴 reversal [ri'və:səl] n. 反转；逆转 vertical ['və:tikəl] adj. 立式的；垂直的 machine center 加工中心
1.Engine Lathes ［1］Engine lathes，of course，are general purpose
machines used in production and maintenance shops all over the world. Sizes range from small bench models to huge heavy duty pieces of equipment. Many of the larger lathes are equipped with auxiliary parts which are not commonly available in ordinary shops，such as automatic stops for the carriage.
板,型板 tapered ['teipəd] adj. 锥形的 groove [gru:v] n. 沟，槽 contour ['kɔntuə] n.轮廓；轮廓线 shaft [ʃɑ:ft] n. 轴
New Words & Expressions
car axle['æ ksl] n.汽车轴 turbine ['tə:bin] n.汽轮机 turret ['tə:rit] n.转台；转塔 tailstock ['teilstɔk] n. 尾座，尾架 accessory [æk'sesəri] n.附件，配件 principal ['prinsəpəl] adj.主要的 screw [skru:] n. 螺丝，螺钉 casting ['kɑ:stiŋ] n. 铸件，铸造
Unit 7 Lathes
Contents
New Words & Expressions Text & Translation Complex Sentence Analysis Key to Exercises
New Words & Expressions
lathe [leið] n. 车床 vt. 车床加工 engine lathe 普通车床 bench model 台式车床 tracer or duplicating lathe 靠模车床或仿形车床 template ['templit] n. (切金属、石、木等用的)样板,模
Text & Translation
2.Tracer or Duplicatiicating lathe is designed to produce
irregularly shaped parts automatically. The basic operation of this lathe is as follows. A template of either a flat or three dimensional shape is placed in a holder. A guide or pointer then moves along this shape and its movement controls that of the cutting tool. The duplication may include a square or tapered shoulder，grooves，tapers，and contours. Work such as motor shafts，spindles，pistons，rods，car axles，turbine shafts，and a variety of other objects can be turned by using this type of lathe.
Text & Translation
Lathes are widely used in manufacturing to produce a great variety of machine parts. Some are used for general purposes and others are used to perform specialized operations.