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零件图A1.dwg

法兰盘零件加工工艺及钻斜孔3-Φ12及3-Φ17.5孔夹具设计【2套夹具】【4张图纸】

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法兰盘零件加工工艺及钻斜孔3-Φ12及3-Φ17.5孔夹具设计【2套夹具】【4张图纸】.rar

零件图A1.dwg---(点击预览)

钻斜孔3-Φ12夹具装配图.dwg---(点击预览)

钻孔3-Φ17.5夹具装配图.dwg---(点击预览)

计划周记进度检查表.xls---(点击预览)

相关资料.doc

计划周记进度检查表.xls

钻孔3-Φ17.5夹具装配图.dwg

钻斜孔3-Φ12夹具装配图.dwg

零件图A1.dwg

摘要III

AbstractIV

目录V

1 绪论1

1.1本课题的研究内容和意义1

1.2国内外的发展概况1

1.3本课题应达到的要求1

2 法兰盘的工艺分析及生产类型的确定3

2.1 法兰盘零件的用途3

2.2 法兰盘零件的工艺分析3

2.3 确定生产纲领和生产类型5

3 确定毛坯绘制毛坯图6

3.1 选择毛坯6

3.2 确定尺寸公差及加工余量6

4 拟定法兰盘工艺路线7

4.1 精基准的选择7

4.2 粗基准的选择7

4.3 加工阶段的划分7

4.4 工序集中及分散7

4.5 工艺路线的选择7

4.5.1 工艺路线方案一7

4.5.2 工艺路线方案二7

4.6 工艺方案的分析8

4.7 最终的加工工艺过程8

5 加工余量，工序尺寸及公差的确定9

5.1 加工余量的确定9

5.2 工序尺寸和公差的确定9

5.3 Φ320mm外圆加工余量，工序尺寸和公差的确定10

5.4 Φ248mm 外圆加工余量，工序尺寸和公差的确定11

5.5 Φ320mm左端面加工余量，工序尺寸和公差的确定12

6 确定切削用量及基本工时16

6.1 合理选择切削用量16

6.1.1 背吃刀量ap的选择16

6.1.2 进给量f的选择16

6.1.3 切削速度vc的选择16

6.2 粗加工切削用量选择原则17

6.2.1切削深度选择18

6.2.2进给量选择18

6.2.3切削速度选择18

6.3精加工时切削用量的选择原则18

6.3.1 切削深度选择18

6.3.2 进给量选择18

6.3.3 切削速度选择18

7 孔的夹具设计19

7.1 研究原始资料,确定夹具的设计方案19

7.1.1 分析工件并确定定位方案19

7.2 确定夹具总装配图的设计19

7.2.1 钻模的选择19

7.2.2 钻模板的选择20

7.2.3 钻套的选择与设计20

7.2.4夹具体定位元件的确定21

7.2.5工件定位元件的确定21

7.2.6 回转分度装置23

7.2.7 对定分度装置机构23

7.2.8 定位器原理23

7.3 夹具的总装配与原理24

8 法兰盘的夹具设计25

8.1定位基准的选择25

8.1.1 选择定位基准的基本方法25

8.1.2 粗基准的选择25

8.1.3 精基准的选择25

8.2确定切削用量及基本工时25

8.2.1 车Φ320mm端面和外圆26

8.2.2 半精车Φ320mm端面和外园26

8.2.3 钻Φ3-12mm孔27

8.3定位误差分析27

8.4夹具设计及操作的简要说明27

致谢29

参考文献30

附录31摘要

　　　法兰盘是一种盘状零件，法兰盘也叫法兰，成对使用。为了保证产品的质量，提高加工效率，需要对其加工工艺进行优化设计，并在关键工序使用专用机床进行加工。本课题即以此为背景，要求学生根据企业生产需要和支座体零件的加工要求，首先完成零件的加工工艺规程设计，在此基础之上，选择其关键工序之一进行专用夹具设计，并完成必要的设计计算。通过查阅相关资料，了解法兰盘用途，性能，特点，看懂零件图，确定毛坯，绘制毛坯图，拟定法兰盘工艺路线，制作工艺卡片等。近几年来，我国在法兰的制造领域和研发领域取得了一定的突破。机械制造工业是为社会提供各种机械设备的部门，在国家的发展中起到很重要的地位，其发展规模及水平反映了一个国家经济实力科技水平的标志。此设计是在大学即将结束前学完了所有学校所安排的课程及实习后所面临的一次考察，是一次理论加实践的一次训练。强化了我们对基础知识和技能的理解和应用程度，培养了我们一定的理论分析，设计运算能力，论证能力，搜集资料能力。在我们四年的大学生活中占很重要作用。

关键词：法兰盘；工艺卡片；毛坯图；夹具设计

Abstract

　　　Flange is a discoid parts, flanges, also called flange, used in pairs. In order to ensure product quality, improve processing efficiency, it is needed to optimize the processing technology, and the use of special machine tool for processing in the critical process. This issue is based on the background, ask the students to production and processing enterprises need and a support body parts requirements, complete the components processing technological process design first, on this basis, choose one of the key process of special fixture design, and completes the essential design calculation. Through access to relevant information, understand the flange uses, properties, characteristics, understand the part drawing, determine blank, drawing blank map, formulate flange process route, process cards etc.. In recent years, China has made certain breakthrough in the field of manufacturing and flange. Machinery manufacturing industry is to provide all kinds of machinery and equipment of the Department for the society, play a very important role in the development of the nation, the development scale and level reflects the symbol of economic strength of a country's scientific and technological level. This design is in the University before the end of the finished all the work of school curriculum and a study faced after practice, is a theoretical and practical training session. To strengthen our on the basic knowledge and skills to understand and apply, cultivate our analysis the theory, design and operation ability, reasoning ability, ability to collect information. Plays an important role in our four years of University life.

Key words: flange; process card; rough map; fixture design

1 绪论

1.1 本课题的意义和研究内容

法兰盘是工业中应用广泛的零件之一，生产量比较大。为了保证产品的质量，提高加工效率，需要对其加工工艺进行优化设计，并在关键工序使用专用机床进行加工。本课题即以此为背景，要求学生根据企业生产需要和支座体零件的加工要求，首先完成零件的加工工艺规程设计，在此基础之上，选择其关键工序之一进行专用夹具设计，并完成必要的设计计算。

本课题的研究内容如下：

（ 1 ）查阅相关法兰盘资料书籍，初步了解法兰盘用途，特点，性能等情况。

（ 2 ）确定该法兰盘零件属于大批量生产及其工艺特征。

（ 3 ）仔细看懂零件图，根据图中的技术要求以及尺寸，看其各项条件是否准确合理及其工艺能否达到要求。

（ 4 ）确定毛坯，绘制毛皮图。毛坯种类对提高生产率，降低成本，节约材料有很大影响，根据零件结构选择毛坯。

（ 5 ）拟定法兰盘工艺路线。加工余量，工序尺寸及其公差的确定。确定切削量及其工时。分出工序，安装或工位及工步等。通过查阅《切削用量手册》《机械加工工艺手册》来确定工序使用的刀具、机床型号、进刀量、夹具及量具等等。

（ 6 ）制作工艺卡片。填写完成后，认真检查卡片中的数据是否有错误。

（ 7 ）设计斜孔与径向孔钻模。

（ 8 ）设计说明书。完成后，认真检查说明书是否有错误。

（ 9 ）整理好毕业设计所有的材料，确定无误后装好。

1.2 国内外的发展概况

近几年来，我国在法兰的制造领域和研发领域取得了一定的突破，因产业链和市场的影响，加上政策的支持，大量的工厂和个人加工作坊开始大批量的生产和销售法兰成品。经调查发现，近几年全球在法兰方面的市场容量联创新高，产销规模大幅增加，价格也居高不下。由此导致的研究领域在开发法兰产品方面也加快了步伐，各种类型和功能的法兰产品层出。

　　　国际法兰是按照国家标准要求的尺寸，公差范围等生产的法兰盘，区别于不按标准尺寸生产的法兰片也称二标法兰（有人叫非标法兰式不正确的），通常一些无良商家会减少法兰盘厚皮，外径两项尺寸来达到节省材料的目的。还有用废旧的钢材或边角料钢材加工法兰，这种私炼钢使用的炼钢技术陈旧无法保证力学性能的焊接性能，使用时间可能无法和钢管焊接，或者钢材本身就有裂缝，气孔等焊接上去后会漏水，所以购买法兰盘时尽量选用国际法兰。如果资金有限选择二标法兰的情况下一定要仔细观察并测量法兰尺寸以免上当。

　　　通过这样一个典型环节综合训练，达到综合训练学生运用所学知识，解决工程实际问题的能力。

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内容简介：: 无锡太湖学院机械加工工序卡片安装工步安装及工步说明刀具量具走刀长度走刀次数1锻打专用量具设计王金华指导工序名称锻打工序号1零件名称法兰盘零件号零件重量 40kg同时加工零件数1 材料毛坯牌号硬度型式重量 HT200 HBW160-260模锻件设备夹具辅助工具名称型号切削深度进给量主轴转速切削速度基本工时陈老师共11页第1页无锡太湖学院机械加工工序卡片安装工步安装及工步说明刀具量具走刀长度走刀次数2退火专用量具设计王金华指导工序名称退火工序号零件名称法兰盘零件号零件重量 40kg同时加工零件数1 材料毛坯牌号硬度型式重量HT200 HBW151-229 模锻件设备夹具辅助工具名称型号切削深度进给量主轴转速切削速度基本工时陈老师共11页第2页无锡太湖学院机械加工工序卡片安装工步安装及工步说明刀具量具走刀长度走刀次数3夹直径为320的外圆车另一端面和外圆yT15专用量具1303设计王金华指导工序名称车工序号零件名称法兰盘零件号零件重量 40kg同时加工零件数1 材料毛坯牌号硬度型式重量HT200 HBW160-260 模锻件设备夹具辅助工具名称型号专用夹具卧式车床 CA6140切削深度进给量主轴转速切削速度基本工时1.60.15mm/r 160r/min 20m/min0.43陈老师共11页第3页无锡太湖学院机械加工工序卡片安装工步安装及工步说明刀具量具走刀长度走刀次数4掉头夹另一端外圆，车另一端面和外圆yT15专用量具1603设计王金华指导工序名称车工序号零件名称法兰盘零件号零件重量 40kg同时加工零件数1 材料毛坯牌号硬度型式重量HT200 HBW160-260 模锻件设备夹具辅助工具名称型号切削深度进给量主轴转速切削速度基本工时1.60.15mm/r 160r/min 20r/min0.65陈老师共11页第4页无锡太湖学院机械加工工序卡片安装工步安装及工步说明刀具量具走刀长度走刀次数5粗镗直径为90,101,209的孔弯头镗刀专用量具1501设计王金华指导工序名称车工序号零件名称法兰盘零件号零件重量 40kg同时加工零件数1 材料毛坯牌号硬度型式重量HT200 HBW160-260 模锻件设备夹具辅助工具名称型号专用夹具镗床 T6212切削深度进给量主轴转速切削速度基本工时0.3mm/r960r/min 150mm/min1.23陈老师共11页第5页无锡太湖学院机械加工工序卡片安装工步安装及工步说明刀具量具走刀长度走刀次数6精镗直径为90,101,209的孔弯头镗刀专用量具1501设计王金华指导工序名称镗工序号零件名称法兰盘零件号零件重量 40kg同时加工零件数1 材料毛坯牌号硬度型式重量HT200 HBW160-260 模锻件设备夹具辅助工具名称型号专用夹具镗床 T6212切削深度进给量主轴转速切削速度基本工时1mm/r1450r/min80mm/min陈老师共11页第6页无锡太湖学院机械加工工序卡片安装工步安装及工步说明刀具量具走刀长度走刀次数7钻直径为17.5的孔高速钢锥柄麻花钻专用量具251设计王金华指导工序名称钻工序号零件名称法兰盘零件号零件重量 40kg同时加工零件数1 材料毛坯牌号硬度型式重量HT200 HBW160-260 模锻件设备夹具辅助工具名称型号专用夹具立式钻床 Z525切削深度进给量主轴转速切削速度基本工时35m/min550r/min31.4mm/min0.63陈老师共11页第7页无锡太湖学院机械加工工序卡片安装工步安装及工步说明刀具量具走刀长度走刀次数8钻3-12孔高速钢锥柄麻花钻专用量具301设计王金华指导工序名称钻工序号零件名称法兰盘零件号零件重量 40kg同时加工零件数1 材料毛坯牌号硬度型式重量HT200 HBW160-260 模锻件设备夹具辅助工具名称型号专用夹具卧式机床切削深度进给量主轴转速切削速度基本工时35m/min555r/min31.4mm/min0.63陈老师共11页第8页无锡太湖学院机械加工工序卡片安装工步安装及工步说明刀具量具走刀长度走刀次数9钻3-12孔高速钢锥柄麻花钻专用量具1021设计王金华指导工序名称钻工序号零件名称法兰盘零件号零件重量 40kg同时加工零件数1 材料毛坯牌号硬度型式重量HT200 HBW160-260 模锻件设备夹具辅助工具名称型号专用夹具立式钻床 Z525切削深度进给量主轴转速切削速度基本工时35m/min555r/min31.4mm/min0.63陈老师共11页第9页无锡太湖学院机械加工工序卡片安装工步安装及工步说明刀具量具走刀长度走刀次数10钻3-12孔高速钢锥柄麻花钻专用量具801设计王金华指导工序名称钻3-12斜孔工序号零件名称法兰盘零件号零件重量 40kg同时加工零件数1 材料毛坯牌号硬度型式重量HT200 HBW160-260 模锻件设备夹具辅助工具名称型号专用夹具立式钻床 Z525切削深度进给量主轴转速切削速度基本工时35m/min555r/min31.4mm/min0.63陈老师共11页第10页无锡太湖学院机械加工工序卡片安装工步安装及工步说明刀具量具走刀长度走刀次数11检验设计王金华指导工序名称检验工序号零件名称法兰盘零件号零件重量 40kg同时加工零件数1 材料毛坯牌号硬度型式重量HT200 HBW160-260 模锻件设备夹具辅助工具名称型号专用夹具切削深度进给量主轴转速切削速度基本工时陈老师共11页第11页零件号材料 HT200 机械加工工艺过程综合卡片零件名称法兰盘毛坯质量 40kg生产类型大批量生产毛坯种类工序序号工序内容安装工步工序说明锻打退火车削夹直径为320的外圆车另一端面和外圆车削掉头夹另一端外圆，车另一端面和外圆镗削粗镗直径为90的孔粗镗直径为101的孔粗镗直径为209的孔精镗精镗直径为90的孔精镗直径为101的孔精镗直径为209的孔钻削钻直径为17.5的孔钻削钻3-20孔钻削钻3-12孔钻削钻3-12孔铣削检验设计指导审核夹具机床道具量具专用夹具专用组合机床 yT15专用量具 yT15 弯头镗刀专用夹具专用组合机床弯头镗刀专用量具专用夹具专用组合机床高速钢锥柄麻花钻专用量具专用夹具专用组合机床高速钢锥柄麻花钻专用量具专用夹具专用组合机床高速钢锥柄麻花钻专用量具专用夹具专用组合机床高速钢锥柄麻花钻专用量具 HT200 40kg 工序说明夹直径为320的外圆车另一端面和外圆掉头夹另一端外圆，车另一端面和外圆粗镗直径为90的孔粗镗直径为101的孔粗镗直径为209的孔精镗直径为90的孔精镗直径为101的孔精镗直径为209的孔钻直径为17.5的孔钻3-20孔钻3-12孔钻3-12孔检验编号无锡太湖学院毕业设计（论文）题目：法兰盘零件加工工艺信机系机械工程及自动化专业学号： 0923096学生姓名：王金华指导教师：陈伟明（职称：副教授）2013年5月21日无锡太湖学院本科毕业设计（论文）诚信承诺书本人郑重声明：所呈交的毕业设计（论文）法兰盘零件加工工艺是本人在导师的指导下独立进行研究所取得的成果，其内容除了在毕业设计（论文）中特别加以标注引用，表示致谢的内容外，本毕业设计（论文）不包含任何其他个人、集体已发表或撰写的成果作品。班级：机械92 学号： 0923096 作者姓名：年月日无锡太湖学院信机系机械工程及自动化专业毕业设计论文任务书一、题目及专题：1、题目法兰盘零件加工工艺 2、专题二、课题来源及选题依据法兰盘是使管子与管子相互连接的零件，连接在管端，也有用在设备进出口上的法兰。法兰盘上有孔眼，螺栓使两法兰盘紧连，法兰间用衬垫密封，法兰盘之间加上密封点，然后用螺栓紧固不同压力的法兰有不同的厚度和使用不同的螺栓。凡在两个平面周边使用螺栓连接同时封闭的连接零件一般都是法兰。法兰连接就是把两个管道，管件或者器材先各自固定在一个法兰盘上，两个法兰盘之间加上法兰垫，用螺栓紧固在一起，完成了连接。是管道施工的重要连接方式，使用方便，能够承受较大的压力。在工业管道中，其使用十分广泛，在家庭里，管道直径小，而且是低压，看不见法兰连接，如果是在一个锅炉房或者生产现场，到处都是法兰连接的管道和器材三、本设计（论文或其他）应达到的要求：能够自己查阅相关资料，通过书籍，网络等途径加上老师的指导I下独立完成熟练掌握法兰盘用途，特点，性能等情况看懂零件图，根据图中的技术要求以及尺寸，看其各项条件是否准确合理及其工艺能否达到要求并且能够确定毛坯绘制，毛坯图掌握法兰盘工艺路线。加工余量，工序尺寸及其公差的确定确定切削量及其工时。分出工序，安装或工位及工步等能够熟练制作工艺卡片熟练使用CAD画图工具。四、接受任务学生：机械92 班姓名王金华五、开始及完成日期：自2011年11月7日至2012年5月20日六、设计（论文）指导（或顾问）：指导教师签名签名签名教研室主任学科组组长研究所所长签名系主任签名2013年05月20日I英文原文Machining Processing Introduction 1 LatheLathes are machine tools designed primarily to do turning, facing and bori ng, 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. Som 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 transmissionthrough 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 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 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 operators 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 in manufacturing 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 make 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 goes down, 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 todays 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 the parts 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. On high-production runs where maximum output is desirable, a minimum tolerance of 0.125mm is economical on both diameter and length of turn. 机械加工介绍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。车削很少在其他种类的机床上进行，而且任何一种其他机床都不能像车床那样方便地进行车削加工。由于车床还可以用来钻孔和铰孔，车床的多功能性可以使工件在一次安装中完成几种加工。因此，在生产中使用的各种车床比任何其他种类的机床都多。车床的基本部件有：床身、主轴箱组件、尾座组件、溜板组件、丝杠和光杠。床身是车床的基础件。它能常是由经过充分正火或时效处理的灰铸铁或者球墨铁制成。它是一个坚固的刚性框架，所有其他基本部件都安装在床身上。通常在床身上有内外两组平行的导轨。有些制造厂对全部四条导轨都采用导轨尖朝上的三角形导轨（即山形导轨），而有的制造厂则在一组中或者两组中都采用一个三角形导轨和一个矩形导轨。导轨要经过精密加工以保证其直线度精度。为了抵抗磨损和擦伤，大多数现代机床的导轨是经过表面淬硬的，但是在操作时还应该小心，以避免损伤导轨。导轨上的任何误差，常常意味着整个机床的精度遭到破坏。主轴箱安装在内侧导轨的固定位置上，一般在床身的左端。它提供动力，并可使工件在各种速度下回转。它基本上由一个安装在精密轴承中的空心主轴和一系列变速齿轮(类似于卡车变速箱)所组成。通过变速齿轮，主轴可以在许多种转速下旋转。大多数车床有812种转速，一般按等比级数排列。而且在现代机床上只需扳动24个手柄，就能得到全部转速。一种正在不断增长的趋势是通过电气的或者机械的装置进行无级变速。由于机床的精度在很大程度上取决于主轴，因此，主轴的结构尺寸较大，通常安装在预紧后的重型圆锥滚子轴承或球轴承中。主轴中有一个贯穿全长的通孔，长棒料可以通过该孔送料。主轴孔的大小是车床的一个重要尺寸，因此当工件必须通过主轴孔供料时，它确定了能够加工的棒料毛坯的最大尺寸。尾座组件主要由三部分组成。底板与床身的内侧导轨配合，并可以在导轨上作纵向移动。底板上有一个可以使整个尾座组件夹紧在任意位置上的装置。尾座体安装在底板上，可以沿某种类型的键槽在底板上横向移动，使尾座能与主轴箱中的主轴对正。尾座的第三个组成部分是尾座套筒。它是一个直径通常大约在5176mm（23英寸）之间的钢制空心圆柱体。通过手轮和螺杆，尾座套筒可以在尾座体中纵向移入和移出几个英寸。车床的规格用两个尺寸表示。第一个称为车床的床面上最大加工直径。这是在车床上能够旋转的工件的最大直径。它大约是两顶尖连线与导轨上最近点之间距离的两倍。第二个规格尺寸是两顶尖之间的最大距离。车床床面上最大加工直径表示在车床上能够车削的最大工件直径，而两顶尖之间的最大距离则表示在两个顶尖之间能够安装的工件的最大长度。普通车床是生产中最经常使用的车床种类。它们是具有前面所叙的所有那些部件的重载机床，并且除了小刀架之外，全部刀具的运动都有机动进给。它们的规格通常是：车床床面上最大加工直径为305610mm（1224英寸）；但是，床面上最大加工直径达到1270mm（50英寸）和两顶尖之间距离达到3658mm的车床也并不少见。这些车床大部分都有切屑盘和一个安装在内部的冷却液循环系统。小型的普通车床车床床面最大加工直径一般不超过330mm（13英寸）-被设计成台式车床，其床身安装在工作台或柜子上。虽然普通车床有很多用途，是很有用的机床，但是更换和调整刀具以及测量工件花费很多时间，所以它们不适合在大量生产中应用。通常，它们的实际加工时间少于其总加工时间的30%。此外，需要技术熟练的工人来操作普通车床，这种工人的工资高而且很难雇到。然而，操作工人的大部分时间却花费在简单的重复调整和观察切屑过程上。因此，为了减少或者完全不雇用这类熟练工人，六角车床、螺纹加工车床和其他类型的半自动和自动车床已经很好地研制出来，并已经在生产中得到广泛应用。2.数字控制先进制造技术中的一个基本的概念是数字控制（NC）。在数控技术出现之前，所有的机床都是由人工操纵和控制的。在与人工控制的机床有关的很多局限性中，操作者的技能大概是最突出的问题。采用人工控制是，产品的质量直接与操作者的技能有关。数字控制代表了从人工控制机床走出来的第一步。数字控制意味着采用预先录制的、存储的符号指令来控制机床和其他制造系统。一个数控技师的工作不是去操纵机床，而是编写能够发出机床操纵指令的程序。对于一台数控机床，其上必须安有一个被称为阅读机的界面装置，用来接受和解译出编程指令。发展数控技术是为了克服人类操作者的局限性，而且它确实完成了这项工作。数字控制的机器比人工操纵的机器精度更高、生产出零件的一致性更好、生产速度更快、而且长期的工艺装备成本更低。数控技术的发展导致了制造工艺中其他几项新发明的产生：电火花加工技术、激光切割、电子束焊接数字控制还使得机床比它们采用有人工操的前辈们的用途更为广泛。一台数控机床可以自动生产很多类的零件，每一个零件都可以有不同的和复杂的加工过程。数控可以使生产厂家承担那些对于采用人工控制的机床和工艺来说，在经济上是不划算的产品生产任务。同许多先进技术一样，数控诞生于麻省理工学院的实验室中。数控这个概念是50年代初在美国空军的资助下提出来的。在其最初的价段，数控机床可以经济和有效地进行直线切割。然而，曲线轨迹成为机床加工的一个问题，在

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