1、数控机床数控机床 徐存善主编CNC machines 徐存善主编 徐存善主编 Unit 8 CNC machines Early machines tools were operated by craftsmen who decided many variables such as speeds,feeds,and depth of cut,etc1.With the development of science and technology,a new term,numerical control(NC)appeared.Controlling a machine tool using a
2、punched tape or stored program is known as numerical control(NC).NC has been defined by the Electronic Industries Association(EIA)as“A system in which actions are controlled by the direct insertion of numerical data at some point.The system must automatically interpret at least some portion of this
3、datadj.”.徐存善主编 In the past,machine tools were kept as simple as possible in order to keep their costs down.Because of the ever-rising cost of labor,better machine tools,complete with electronic controls,were developed so that industry could produce more and better goods at prices that were competiti
4、ve with those offshore industries.NC is being used on all types of machine tools,from the simplest to the most complex.The most common machine tools are the single-spindle drilling machine,lathe,milling machine,turning center,and machining center.徐存善主编 1.Single-Spindle Drilling Machine One of the si
5、mplest numerically controlled machine tools is the single-spindle drilling machine.Most drilling machines are programmed on three axes:a.The X-axis controls the table movement to the right and left.b.The Y-axis controls the table movement toward or away from the column.c.The Z-axis controls the up o
6、r down movement of the spindle to drill holes to depth.徐存善主编 2.Lathe The engine lathe,one of the most productive machine tools,has always been a very efficient means of producing round parts(Fig.7-1).Most lathes are programmed on two axes:a.The X-axis controls the cross motion(in or out)of the cutti
7、ng tool.b.The Z-axis controls the carriage travel toward or away from the headstock.徐存善主编3.Milling Machine Fig.7-2 the vertical knee and column milling machine The milling machine has always been one of the most versatile machine tools used in industry(Fig.7-2).Operations such as milling,contouring,
8、gear cutting,drilling,boring,and reaming are only a few of the many operations that can be performed on a milling machine4.The milling machine can be programmed on three axes:a.The X-axis controls the table movement left or right.b.The Y-axis controls the table movement toward or away from the colum
9、n.c.The Z-axis controls the vertical(up and down)movement of the knee or spindle.徐存善主编 4.Turning Center Turning Centers were developed in the mid-1960s after studies showed that about 40 percent of all metal cutting operations were performed on lathes.These numerically controlled machines are capabl
10、e of greater accuracy and higher production rates than were possible on the engine lathe.The basic turning center operates on only two axes:a.The X-axis controls the cross motion of the turret head.b.The Z-axis controls the lengthwise travel(toward or away from the headstock)of the turret head.徐存善主编
11、 5.Machining Center Machining centers were developed in the 1960s so that a part did not have to be moved from machine to machine in order to perform various operations.These machines greatly increased production rates because more operations could be performed on a work-piece in one setup.There are
12、 two main types of machining centers,the horizontal and the vertical spindle types.a.The horizontal spindle-machining center operates on three axes:(a)The X-axis controls the table movement left or right.(b)The Y-axis controls the vertical movement(up and down)of the spindle.(c)The Z-axis controls t
13、he horizontal movement(in or out)of the spindle.b.The vertical spindle-machining center operates on three axes:(a)The X-axis controls the table movement left or right.(b)The Y-axis controls the table movement toward or away from the column.(c)The Z-axis controls the vertical movement(up and down)of
14、the spindle.徐存善主编 punch pnt n.冲压机；钻孔机vt.开洞；以拳重击vi.用拳猛击interpret int:prit vt.说明；口译vi.解释；翻译electronic,ilektrnik adj.电子的drill dril n.训练；钻孔机vi.钻孔；训练 carriage krid n.（机床的）滑板；刀架headstock hedstk n.主轴箱milling mili n.铣削contouring knturi n.成形加工boring b:ri n.镗孔；镗削加工 reaming ri:mi n.铰孔knee ni:n.升降台turning t:ni
15、n.车削 徐存善主编knee ni:n.升降台turning t:ni n.车削headstock hedstk n.主轴承accuracy kjursi n.精确性，准确度，精度work-piece w:kpi:s n.工件horizontal hrizntl adj.水平的vertical v:tikl adj.垂直的，直立的production rate 生产率numerical control(NC)数字控制a punched tape 穿孔纸带Technical Terms 徐存善主编the Electronic Industries Association(EIA)（美国）电子工业
16、协会drilling machine 钻床engine lathe 卧式车床gear cutting 齿轮加工turning center 切削中心machining center 加工中心turret head 转塔头metal cutting 金属切削cross motion 横向运动lengthwise travel 纵向运动Language points 徐存善主编1.Early machines were operated by craftsmen who decided many variables such as speeds,feeds,depth of cut,etc.翻译：
17、老式机床通常是由工人操作并由他们决定机床速度、进给量、切削深度等。句中Who decided many variables是定语从句修饰craftsmen。例如：The engineers who we met yesterday have designed a new automatic device.我们昨天碰到的那些工程师设计出了一种新的自动化装置。Language points 徐存善主编 2.NC has been defined as“A system in which actions are controlled by the direct insertion of numeri
18、cal data at some point.The system must automatically interpret at least some portion of this datadj.”数控被定义为“采用在某些点直接插入数字数据来控制操作的系统，此系统必须能够自动解释翻译这些信息中的一部分。”句中as的宾语是A system，which引导的定语从句修饰system。Language points 徐存善主编 3.Because of the ever-rising cost of labor,better machine tools,complete with electro
19、nic controls,were developed so that industry could produce more and better goods at prices that were competitive with those of offshore industries.由于劳动成本日益上涨，人们研制出性能更好的机床，并配有电控设备，这样企业可以生产更多更好价格较低的产品，以和国际上的产品相竞争。句中better machine tools是句子的主语，were developed是句子的谓语，so that引导结果状语从句，that引导的定语从句修饰goods。Lang
20、uage points 徐存善主编 4.Operations such as milling,contouring,gear cutting,drilling,boring,and reaming are only a few of the many operations that can be performed on a milling machine.像铣削、成型加工、齿加工、钻、镗、铰等只是可在铣床上进行的一少部分加工。句中that引导定语从句修饰the many operations。Exercises 徐存善主编I.Answer the following questions ac
21、cording to the text.1.What is meant by the term NC?A system in which actions are controlled by the direct insertion of numerical data at some point.The system must automatically interpret at least some portion of this datadj.The most common machine tools are the single-spindledrilling machine,lathe,
22、milling machine,turning center,and machining center.2.What are the most common machine tools?Exercises 徐存善主编II.Translate the following terms into English.1.数字控制数字控制 2.加工中心加工中心 3.齿轮加工齿轮加工 4.穿孔纸带穿孔纸带 5.数控车床数控车床6.生产率生产率7.垂直运动垂直运动8.电子工业协会电子工业协会numerical control machining centre gear cuttingpunched tape
23、turning centerproduction rateverticalmotionElectronics Industry AssociationExercises 徐存善主编Translate the following into English1.从最简单到最复杂的机床都会用到数控技术。从最简单到最复杂的机床都会用到数控技术。NC is being used on all types of machine tools,from the simplest to the most complex.2.卧式车床是生产效率最高的机床之一。卧式车床是生产效率最高的机床之一。The engine
24、lathe,one of the most productive machine tools.Exercises 徐存善主编 3.研究表明，整个金属材料的切削操作大约研究表明，整个金属材料的切削操作大约40%是是在车床上进行的。在车床上进行的。Studies showed that about 40 percent of all metal cutting operations were performed on lathes.4.卧式加工中心可在三个坐标轴上工作。卧式加工中心可在三个坐标轴上工作。The horizontal spindle-machining center operates
25、 on three axes.徐存善主编 科技英语科技英语(English for Science and Technology(English for Science and Technology，简称，简称EST)EST)可以泛指一切论及或谈及科学和技术的书面语和口语。其可以泛指一切论及或谈及科学和技术的书面语和口语。其中包括：一、科技著述、科技论文和报告、实验报告和方案；中包括：一、科技著述、科技论文和报告、实验报告和方案；二、各类科技情报和文字资料；三、科技实用手册的结构描述二、各类科技情报和文字资料；三、科技实用手册的结构描述和操作规程；四、有关科技问题的会谈、会议、交谈的用语；和操
26、作规程；四、有关科技问题的会谈、会议、交谈的用语；五、有关科技的影片、录像等有声资料的解说词等等。本章首五、有关科技的影片、录像等有声资料的解说词等等。本章首先介绍科技英语的特征。先介绍科技英语的特征。科技英语词汇概括起来主要有科技英语词汇概括起来主要有 5 5个特点：（个特点：（1 1）科技英）科技英语词汇多源于希腊语和拉丁语；（语词汇多源于希腊语和拉丁语；（2 2）词义专一；（）词义专一；（3 3）前后缀）前后缀出现频率高；（出现频率高；（4 4）专业词汇出现的频率低；（）专业词汇出现的频率低；（5 5）广泛使用缩）广泛使用缩略词。科技英语词汇可以分为三种类：科技词汇、略词。科技英语词汇可
27、以分为三种类：科技词汇、半科技词汇半科技词汇和非科技词汇。和非科技词汇。科技英语词汇的结构和特征科技英语词汇的结构和特征 徐存善主编1科技词汇（科技词汇（technical terms）科技英语有许多专门的术语，只在某一特定科技英语有许多专门的术语，只在某一特定的科技领域来用。许多情况下，虽然同为科学家，的科技领域来用。许多情况下，虽然同为科学家，这个领域的科学家并不明白另一领域的词汇，比如这个领域的科学家并不明白另一领域的词汇，比如物理学家就可能不明白生物学领域的专业术语。且物理学家就可能不明白生物学领域的专业术语。且由于科学技术发展，科技术语由于科学技术发展，科技术语(词汇词汇)也日益增多
28、。也日益增多。这些科技词汇只有该领域的专家或工作人员了解。这些科技词汇只有该领域的专家或工作人员了解。例如：化学领域中的例如：化学领域中的isotopeisotope（同位素）；物理领（同位素）；物理领域的域的photon(photon(光子光子)；以及生物领域的；以及生物领域的chromosome(chromosome(染色体染色体)等等，都是科技词汇。等等，都是科技词汇。徐存善主编2.半科技词汇（半科技词汇（semi-technical terms）半科技词汇指的是那些不同于生活中的语言词汇，而半科技词汇指的是那些不同于生活中的语言词汇，而且在不同领域又有不同的含义的词汇，也称通用科技术语
29、且在不同领域又有不同的含义的词汇，也称通用科技术语。例如。例如 orbit,orbit,在医学上指的是在医学上指的是“眼眶眼眶”，而在物理学上，而在物理学上则是则是“轨道轨道”；operation,operation,在医学上指的是在医学上指的是“手术手术”，在，在计算机领域是计算机领域是“操作操作”，而在商务上却是，而在商务上却是“公司公司”；a a huge multinational electronics operationhuge multinational electronics operation在数学上指在数学上指的是的是“运算运算”。很普通的词很普通的词web(web(网网)
30、、net(net(网网)、site(site(站站点点)在计算机科学中都成了与原词仍然关联的专业词汇，在计算机科学中都成了与原词仍然关联的专业词汇，如如web site(web site(网址、网站网址、网站)、internet(internet(互联网互联网)；Mouse(Mouse(老老鼠鼠)、memory(memory(记忆记忆)、read(read(阅读阅读)分别成了计算机科学中分别成了计算机科学中的术语的术语“鼠标鼠标”、“内存内存”和和“读取读取”。徐存善主编3 3 非科技词汇（非科技词汇（non-technical termsnon-technical terms）非科技词汇经常
31、用于科学技术领域的词汇，在日常生非科技词汇经常用于科学技术领域的词汇，在日常生活当中则不常用的词汇，在修辞学上指的是那些正式用语活当中则不常用的词汇，在修辞学上指的是那些正式用语（learned and formal wordslearned and formal words）。）。因为科技英语是一种因为科技英语是一种描述各种自然现象、客观事实的发生过程和特性的语言，描述各种自然现象、客观事实的发生过程和特性的语言，所以科技英语的文章不用那些日常生活中的常用词汇（所以科技英语的文章不用那些日常生活中的常用词汇（common wordscommon words）。）。例如，日常生活中我们用例如，
32、日常生活中我们用givegive、havehave，而科技英语，而科技英语中我们用中我们用possesposses；日常生活中用；日常生活中用refer torefer to，科技英语中用，科技英语中用allude toallude to，日常生活中用，日常生活中用madmad，科技英语中用，科技英语中用 insane insane 等等等。等。徐存善主编Advantages of NC 徐存善主编 Advantages of NC Recent studies show that of the amount of time an average part spent in a shop,on
33、ly a fraction of that time was actually spent in the machining process.Let us assume that a part spent 50 hours from the time it arrived at a plant as a rough casting or bar stock to the time it was a finished product.During this time,it would be on the machine for only 2.5 hours and be cut for only
34、 0.75 hour.The rest of the time would be spent on waiting,moving,setting up,loading,unloading,inspecting the part,setting speeds and feeds,and changing cutting tools.近期研究表明，在加工零件时，只有一少部分时间真正用于加工工件。假定把毛坯或棒料加工为成品零件需要50h,那么,工件在机床上的时间只有2.5h,用于切削的时间仅有0.75h,其余时间都用在等待加工、运输、安装、装夹、拆卸、检验、设置转速与进给、换刀上。徐存善主编NC r
35、educes the amount of non-chip-producing time by selecting speeds and feeds,making rapid moves between surfaces to be cut,using automatic fixtures,automatic tool changing,controlling the coolant,in-process gauging,and loading and unloading the part.These factors,plus the fact that it is no longer nec
36、essary to train machine operators,have resulted in considerable savings throughout the entire manufacturing process and caused tremendous growth in the use of NC.Some of the major advantages of NC are as follows:通过转速与进给量的设定、刀具在待切削表面间的快速移动、自动夹具的运用、刀具的自动切换、切削液的控制、在线检测及零件的自动装卸，NC缩短了非切削加工的时间。上述因素,加之无需培训
37、机床操作工,使整个加工过程耗时大量减少，促进了数控的推广应用。NC的主要优点如下:徐存善主编Helical gears have certain advantages,for example,when connecting parallel shafts,they have a higher load carrying capacity than spur gears with the same tooth numbers and cut with the same cutter.Because of the overlapping action of the teeth,they are s
38、moother in action and can operate at higher pitch-line velocities than spur gears.The pitch-line velocity is the velocity in the pitch circle.Since the teeth are inclined to axis of rotation,helical gears create an axial thrust.If used single,this thrust must be absorbed in the shaft bearings.The th
39、rust 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.Double-hel
40、ical gears are well suited for the efficient transmission of power at high speeds.斜齿轮具有某些优点。例如当连接平行轴时，其承载能力高于有相同齿数并用相同刀具切削的正齿轮。由于轮齿的重合作用，其传动更为平稳，允许的节线速度比正齿轮高。节线速度是节圆上的线速度。因为轮齿倾斜于旋转轴线，所以斜齿轮会产生轴向推力。如果单独使用这种齿轮，轴向推力由轴向轴承来承担。轴向推力问题可通过在一个齿坯上加工两对斜齿来解决。根据加工方法，这种齿轮可以是连续齿人字型齿轮或有退刀槽的双斜齿轮。双斜齿轮非常适于在高速下高效传输动力。徐存善
41、主编(1)There is automatic or semiautomatic operation of machine tools.The degree of automation can be selected as required.(2)Flexible manufacturing of parts is much easier.Only the tape needs changing to produce another part.(3)Storage space is reduced.Simple work-holding fixtures are generally used,
42、reducing the number of jigs or fixtures that must be stored(4)Small part lots can be run economically.Often a single part can be produced more quickly and better by NC.(5)Nonproductive time is reduced.More time is spent on machining the part,and less time is spent on moving and waiting.1)机床可以自动运行，亦可
43、半自动运行，使用时按需要选取2)零件的柔性制造更为简便。更换纸带即可加工不同零件。3)减小存储空间，通常采用简单的工装夹具，因而减少了存储夹具的数量。4)加工小批量零件非常经济。用NC机床加工出的单件质量好且加工快。5)缩短非加工时间。花在加工零件上的时间多了，用于运输和等待的时间短了。徐存善主编 (6)Tooling costs are reduced.In most cases complex jigs and fixtures are not required.(7)Inspection and assembly costs are lower.The quality of the pr
44、oduct is improved,reducing the need for inspection and ensuring that parts fit as required.(8)Machine utilization time is increased.There is less time that a machine tool is idle because work piece and tool changes are rapid and automatic.(9)Complex forms can easily be machined.The new control unit
45、features and programming capabilities make the machining of contours and complex forms very easy.(10)Parts inventory is reduced.Parts can be made as required from the information on the punched tape.6)降低加工成本。数控机床在多数情况下无需复杂夹具。7)降低检验与装配成本。产品质量提高了，因而减少了检验的必要，保证零件能按需装配。8)增加机床使用时间。由于能迅速自动地更换工件与刀具，机床闲置时间缩
46、短了。9)便于加工复杂形状的工件。新型控制器功能多、编程能力强，因而轮廓加工与复杂形状的加工非常方便。10)减少零件存货。人们能根据穿孔带上的信息加工所要求的零件 徐存善主编 Since the first industrial revolution,about 200 years ago,NC has had a significant effect on the industrial world.The developments in the computer and NC have extended a persons mind and muscle.The NC unit takes
47、symbolic input and changes it to useful output,expanding a persons concepts into creative and productive results.NC technology has made such rapid advances that it is being used in almost every area of manufacturing,such as machining,welding,press-working,and assembly.If industrys planning and logic
48、 are good,the second industrial revolution will have as much or more effect on society as the first industrial revolution had.As we progress through the various stages of NC,it is the entire manufacturing process thatmust be kept in mind.如果工业规划合理、逻辑正确，与第一次工业革命一样，第二次工业革命将对人类社会产生同样甚至更大的影响。在我们从事NC不同阶段的
49、工作时，必须牢记NC技术贯穿于整个加工过程的始终。回顾数控技术的发展历史，我们相信计算机辅助制造（CAM）与计算机集成制造（CIM）是制造业的发展趋势，自动化工厂在不远的未来将成为现实 徐存善主编 Computer-assisted manufacturing(CAM)and computer-integrated machining(CIM)are certainly where the future of manufacturing lies,and considering the developments of the past,it will not be too far in the
50、 future before the automated factory is a reality.Developed originally for use in aerospace industries,NC is enjoying widespread acceptance in manufacturing.The use of CNC machines continues to increase,becoming visible in most metalworking and manufacturing industries.Aerospace,defense contract,aut
