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关键词：: 套筒工艺铣床夹具设计 cad图纸

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套筒工艺及铣床夹具设计

40页 12000字数+说明书+外文翻译+答辩稿+2张CAD图纸【详情如下】

外文翻译-基本加工工序和切削技术.doc

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套筒工艺及铣床夹具设计论文.docx

套筒零件图.dwg

铣槽夹具装配图.dwg

摘要

　　　工艺学是研究机械加工工艺技术和夹具设计为主的技术学科,具有很强的实践性,要求学习过程中应紧密联系生产实践,同时它又具有很强的综合性。本次毕业设计研究的课题是套筒零件加工工艺编制及铣床夹具设计，主要内容如下：首先，对零件进行分析，根据零件图提出的具体加工要求，确定毛坯的制造形式和尺寸。第二步，进行基面的选择，确定加工过程中的粗基准和精基准。根据选好的基准，制定工艺路线方案，第三步，根据已经确定的工艺路线，选择加工设备及工艺装备，再确定每一工步的切削用量。在机械设计制造各行业的工艺过程中广泛应用着各种不同的，用以固定加工对象，使之占有正确位置，以便接受施工的一种工艺装备，通称为夹具。本次夹具设计则是设计铣套筒圆弧R10mm 的夹具。设计夹具先对原始资料进行分析，明确设计的要求和意图，然后提出具体的定位、夹紧、对刀方案和夹具体的一般结构。为保证设计的可靠性，还要对夹具的夹紧力和精度进行了分析。同时使设计基准与定位基准相重合，保证了槽侧面的加工精度与位置公差。然后确定夹具结构方案，然后开始切削力、夹紧力的计算和定位误差的分析。最后，把整个设计过程整理为设计说明书和图纸，至此整个设计基本完成。　　

关键词：套筒，加工工艺，铣床夹具

ABSTRACT

　　　Technology is the technology research of mechanical processing technology and fixture design, has a strong practice, requirements should be closely combined with the production practice in the learning process, and it also has the very strong comprehensive. The graduation design topic is the preparation technology of the sleeve parts processing and milling fixture design, the main contents are as follows: firstly, the analysis of parts, according to the specific part drawing processing requirements, determine the manufacture of blank shape and size. The second step, the selection of base, determine the processing of crude and refined baseline benchmark. According to the chosen benchmark, creating process flow scheme, the third step, according to process routes have been identified, select the processing equipment and process equipment, then determine the amount of cutting each work step. In the process of mechanical design and manufacturing industries in a wide variety of applications, for processing a fixed object, so that possession of the correct position, to receive a construction techniques and equipment, known as the fixture. The jig design is the fixture design of arc milling sleeve R10mm. Fixture design first carries on the analysis to the original data, make clear of the design requirements and intentions, and then put forward specific positioning, clamping, clamping tool setting scheme and general structure of concrete. In order to ensure the design reliability, but also on the clamping force and precision was analyzed. At the same time the design standard and the locating datum coincide, ensure the machining precision and position tolerance groove side. Then determine the structure scheme of fixture, calculation and positioning error analysis and began cutting force, clamping force. Finally, the whole design process for the design specifications and drawings, thus the whole design is basically completed.

Keywords: sleeve, machining, milling fixture

第一章绪论1

第二章套筒零件图分析3

2.1 套筒零件图的分析3

2.1.1 套筒结构特点3

2.1.2 套筒作用4

2.1.3 套筒工艺分析4

第三章套筒工艺过程分析7

3.1确定毛坯7

3.1.1 毛坯选择7

3.1.2 绘制毛坯图8

3.2拟定工艺路线8

3.2.1 各表面加工方法8

3.2.2 定位基准的选择19

3.2.3 加工阶段的划分20

3.2.4 工序集中与分散21

3.2.5 热处理工序安排22

3.2.6 辅助工序的安排22

3.2.7 重要工序的分析22

3.3 加工余量的确定23

3.4 尺寸链计算24

第四章铣床夹具设计26

4.1 定位装置的设计26

4.2夹紧装置的设计26

4.3绘制夹具总图26

4.4夹具操作简述27

4.5夹具精度校核27

第五章结论29

参考文献30

致谢31

毕业小结32

附录34

　　　夹具：机械制造过程中用来固定加工对象，使之占有正确的位置，以接受施工或检测的装置。

　　　铣床夹具：均安装在铣床工作台上，随机床工作台作进给运动。主要由定位装置、夹紧装置、夹具体、连接元件、对刀元件组成。铣削加工时，切削力较大，又是断续切削，振动较大，因此铣床夹具的夹紧力要求较大，夹具刚度、强度要求都比较高。本设计主要采用AutoCAD软件对套筒R10圆弧快速夹具设计.根据零件图的特点对套筒R10圆弧快速夹具进行设计，首先是确定套筒R10圆弧快速夹具的大致模样，夹具设计的几点要求是保证工件的加工精度、提高生产效率、工艺性能好、使用性能好、经济性好，夹紧可采用偏心轴夹紧，通过偏心轴旋转的不同偏心距来夹紧与松弛。设计好后，对夹具进行绘制。夹具设计其实也就是对加紧和定位的设计，只要夹紧设计定位好后，基本上夹具就完成了，但这只是基本，还要对他进行别的设计，比如首先保证夹具的安全性、工件的加工精度、提高生产效率、工艺性能好、使用性能好、经济性好，又比如可浮动、可联动、可增力、可自锁、快速装夹等等，这些都很重要，所以设计要从各方面不同的角度考虑夹具设计这个问题。

　　　工艺规程：是指导施工的技术文件。一般包括以下内容：零件加工的工艺路线，各工序的具体加工内容，切削用量、工时定额以及所采用的设备和工艺装备等。

　　　 1．工艺规程是工厂进行生产准备工作的主要依据，产品在投入生产之前要作大量的生产准备工作，包括原材料和毛坯的供应，机床的配备和调整，专用工艺装备的设计制造，核算生产成本以及配备人员等，所有这些工作都要根据工艺规程进行。

　　2．工艺规程是企业组织生产的指导性文件工厂管理人员根据工艺规程规定的要求，编制生产作业计划，组织工人进行生产，并按照工艺规程要求验收产品。

　　3．工艺规程是新建和扩建机械制造厂（或车间）的重要技术文件

　　新建和扩建机械制造厂（或车间）须根据工艺规程确定机床和其他辅助设备的种类、型号规格和数量，厂房面积，设备布置，生产工人的工种、等级及数量等。

　　此外，先进的工艺规程还起着交流和推广先进制造技术的作用。典型工规程可以缩短工厂摸索和试制的过程。2.1.1 套筒结构特点

本设计的套筒的材料为38CrMnAlA，其硬度为HB45-70，抗拉强度为σb=14-23kgf/mm2，此零件内外径孔偏心，还有一垂直孔也是偏离两个中心轴，由于其特殊性，这个加工工艺必须慎重考虑，必须使用一些专用夹具，是其加工准确，以保证精度。另外最主要的一步，也是我们这个课题所要研究的一部，那就是铣R10mm圆弧，因为此圆弧不是标准的1/4圆弧，圆心很不规则，所以我们需要设计专用夹具，来保证套筒此工艺的顺利进行，以保证图纸里要求的加工精度。

2.1.2 套筒作用

　　　抵住轴承的内环，上紧穿钉后减少穿钉和轴承不必要的打滑，没有那东西，轴承内环会直接在穿钉上转（也可以说成轴承内环会跟着外环转动），这样轴承就得不到充分的运转，从而速度降低。

2.1.3 套筒工艺分析

　　　1、查零件图的完整性：

　　　审查零件图上的尺寸标注是否完整、结构表达是否清楚。

　　　2、分析技术要求是否合理：

　　　加工表面的尺寸精度；要加工表面的形状精度；主要加工表面的相互位置精度；表面质量要求；热处理要求。

　　　零件上的尺寸公差、形位公差和表面粗糙度的标注，应根据零件的功能经济合理地决定。过高的要求会增加加工难度，过低的要求会影响工作性能，两者都是不允许的。

　　　3、审查零件材料选用是否适当：

　　　材料的选择既要满足产品的使用要求，又要考虑产品成本，尽可能采用常用材料，如45号钢，少用贵重金属。

　　　4、零件的结构工艺性分析：

　　　由于本产品的精度要求比较高，再加上零件又是偏心还有钻孔加工，则需要选择好定位基准，需要采用粗车→精车既卡完成车削加工。所以车削后，还需要进行粗磨，精磨。考虑加工的效率和加工的经济性车床选用CA6140，，铣床选用X6012，钻床选用Z525台式钻床和Z3025*10两种。磨床因加工表面不同选用M1432A，外圆磨床MQ1312和M2110三种。拟定工艺路线时，在考虑主要表面加工的同时，还要考虑次要表面的加工和热处理，参照附录表可知，这些表面的加工顺序为：粗车端面—铣平面—车外圆—粗磨—精磨—研磨。要求不高的外圆表面、次要表面如退刀槽、倒角、螺纹，应在车外圆时加工。渗碳安排在中间检验后以便提高表面层的耐磨性,同时保持心部有高的耐冲击能力,即强韧性。磁力探伤安排在零件外圆精磨之后检验外圆表面是否有缺陷。

　　　该套筒的加工顺序：毛坯→粗车端面外圆及切断→精车端面→铣键槽→钻孔→去毛刺→钻孔→镗孔→钻孔→中间检验→调制处理→半精车外圆→镗内孔→精磨端面→精磨外圆→渗N→粗磨内孔→精磨内孔→磁力探伤→研磨内孔→终检3.1确定毛坯

3.1.1 毛坯选择

　　　机械加工中常用毛坯的种类:毛坯的种类很多，同一种毛坯又有多种制造方法，机械制造中常用的毛坯有以下几种：

　　　1．铸件形状复杂的零件毛坯，宜采用铸造方法制造。目前铸件大多用砂型铸造，它又分为木模手工造型和金属模机器造型。木模手工造型铸件精度低，加工表面余量大，生产率低，适用于单件小批生产或大型零件的铸造。金属模机器造型生产率高，铸件精度高，但设备费用高，铸件的重量也受到限制，适用于大批量生产的中小铸件。其次，少量质量要求较高的小型铸件可采用特种铸造（如压力铸造、离心制造和熔模铸造等）。

　　　2．锻件机械强度要求高的钢制件，一般要用锻件毛坯。锻件有自由锻造锻件和模锻件两种。自由锻造锻件可用手工锻打（小型毛坯）机械锤锻（中型毛坯）或压力机压锻（大型毛坯）等方法获得。这种锻件的精度低，生产率不高，加工余量较大，而且零件的结构必须简单；适用于单件和小批生产，以及制造大型锻件。模锻件的精度和表面质量都比自由锻件好，而且锻件的形状也可较为复杂，因而能减少机械加工余量。模锻的生产率比自由锻高得多，但需要特殊的设备和锻模，故适用于批量较大的中小型锻件。

　　　3．型材型材按截面形状可分为：圆钢、方钢、六角钢、扁钢、角钢、槽钢及其它特殊截面的型材。型材有热轧和冷拉两类。热轧的型材精度低，但价格便宜，用于一般零件的毛坯；冷拉的型材尺寸较小、精度高，易于实现自动送料，但价格较高，多用于批量较大的生产，适用于自动机床加工。

　　　4．焊接件焊接件是用焊接方法而获得的结合件，焊接件的优点是制造简单、周期短、节省材料，缺点是抗振性差，变形大，需经时效处理后才能进行机械加工。除此之外，还有冲压件、冷挤压件、粉末冶金等其它毛坯。毛坯种类的选择不仅影响毛坯的制造技术及费用，而且也与零件的机械加工技术和加工质量密切相关。为此需要毛坯制造和机械加工两方面的技术人员密切配合，合理地确定毛坯的种类、结构形状，并绘出毛坯图。

　　　根据套筒的结构分析，考虑到套筒的内外表面均为圆表面，且材料38CrMnAlA，因此毛坯的选择为棒料最好，使毛坯的形状和尺寸尽量与零件的形状接近，节省了劳动力和费用。图纸如图3-1所示.3.2.2定位基准的选择

　　　定位基准是指在机械加工中用来确定工件位置的基准面，它的合理选择对保证加工精度，安排加工顺序和提高加工生产率有重要影响。

　　　第一道工序只能以毛坯表面作为定位基准面，这种基准面称为粗基准。在以后的工序中用已加工过的表面定位，这种基准面称为精基准。

　　　在制定零件加工的工艺规程时，正确地选择工件的定位基准有着十分重要的意义。定位基准选择的好坏，不仅影响零件加工的位置精度，而且对零件各表面的加工顺序也有很大的影响。合理选择定位基准是保证零件加工精度的前提，还能简化加工工序，提高加工效率。

　　　粗基准的选择

　　　粗基准的选择，主要影响不加工表面与加工表面的相互位置精度以及影响加工表面的余量分配。因此，选择粗基准要遵循一些基本原则：

　　　1．合理分配加工余量原则

　　　若工件必须首先保证某重要表面的加工余量，则应选择该表面作为粗基准。

　　　在没有要求保证重要表面加工余量均匀的情况下，若零件上每个表面都要加工，则应该以加工余量最小的表面作为粗基准。

　　　2．保证零件加工表面相对于不加工表面具有一定位置精度的原则。

　　　在与1相同的前提条件下，若零件上有的表面不需要加工，则应该以不加工的表面中雨技工表面的位置精度要求较高的表面作为粗基准以达到厚壁均匀外形对称等要求。

　　　3．便于装夹原则。

　　　选用粗基准的表面应尽量平整光滑，不应该有飞边、浇口、冒口及其他缺陷，这样可减少定位误差，并能保证零件夹紧可靠。

　　　4．粗基准一般不得重复使用原则

　　　当毛坯是精密铸件时，毛坯的质量很高，如果工件的加工精度要求不高，这时可以重复使用某一粗基准。

(二)精基准的选择

　　精基准的选择应从保证零件的加工精度、特别是加工表面的相互位止精度来考虑，同时也要照顾到装夹方便，夹具结构简单。选择精基准一般应该遵循以下原则：

　　　1．基准重合原则

　　　选用设计基准作为定位基准，以避免定位基准与设计基准不重合而引起的基准不重合误差。

　　　2. 基准同一原则

　　　应采用同一组基准定位加工零件上尽可能多的表面，这就是基准统一原则。这样做可以简化工艺规程的制订工作，减少夹具设计、制造工作量和成本，缩短生产准备周期；由于减少了基准转换，便于保证各加工表面的相互位置精度

　　　3. 自为基准原则

　　　某些要求加工余量小而均匀的精加工工序，选择加工表面本身作为定位基准，称为自为基准原则。

　　　4. 互为基准原则

　　　当对工件上两个相互位置精度要求很高的表面进行加工时，需要用两个表面互相作为基准，反复进行加工，以保证位置精度要求。

　　　5. 便于装夹原则

　　　所选精基准应保证工件安装可靠，夹具设计简单、操作方便。

　　　根据以上原则，粗基准：以外圆柱表面为粗基准；

　　　精基准：以加工过的外圆柱面和内孔为精基准。

3.2.3 加工阶段的划分

　　　本工艺分三阶段进行，即粗加工，半精加工，和精加工阶段，光整加工阶段。

　　　粗加工阶段：在该阶段高效地切除加工表面的大部分余量，使毛坯形状和尺寸上接近成品套筒，主要加工完成粗车外圆及端面和各个内孔的加工，即粗车端面、外圆及切断；钻孔

　　　半精加工阶段：任务是达到一般的技术要求。即各次要表面达到最终要求，并为主要表面的精加工工作做准备，本次加工为半精加工的为铣键槽；钻孔；镗孔；钻孔；半精车外圆；粗磨内孔。

精加工阶段：其任务是达到零件的全部技术要求。（主要是保证主要表面的加工质量），在零件上有特别高的表面（精度在5级以上，光洁度在10以上时，还要在精加工阶段后，进行加工。）本次加工为精加工的是精车端面；精磨端面；　　　本次的毕业设计的题目是套筒工艺及铣床设计,根据对毛坯的各方面的分析，选择了棒料38CrMnAlA，然后对毛坯进行了加工，加工工序为毛坯→粗车端面外圆及切断→精车端面→铣键槽→钻孔→去毛刺→钻孔→镗孔→钻孔→中间检验→调制处理→半精车外圆→镗内孔→精磨端面→精磨外圆→渗N→粗磨内孔→精磨内孔→磁力探伤→研磨内孔→终检一系列的加工，以及零件工艺卡片的制作，所编制的工艺规程合理，可以满足它的加工要求。最后进行了铣床夹具的设计，将V型块通过件7和件8将其固定，螺钉拧紧；再将件5定位销嵌入夹具底板中，保证高度；将工件套筒放到V型块中间，上铰链螺栓、压板，将铰链螺栓拧紧；然后将对刀块按照需要固定在夹具体上；最后将定位键固定在夹具体上边。所设计的夹具定位准确，结构合理，操作简便，能够满足工序的加工要求。

参考文献

　[1] 《现代制造工艺基础》侯忠滨编西工大讲义 2001年12月

[2]《机床夹具设计》闫光明编西工大讲义 2001年12月

　[3] 《机械制造工艺学》荆长生主编西工大出版社 1998年

[4] 《金属切削原理与道具》陆剑中孙家宁编 2005年1月

[5] 《互换性与测量技术基础》韩进宏王长春编 2006年8月

[6] 《切削用量简明手册》艾兴、肖诗纲机械工业出版社

　[7] 《金属工艺学》邓文英郭小鹏编 1999年11月

[8] 《机械制图》马兰 2006年5月

[9] 《机械设计》濮良贵纪名刚编 2005年12月

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内容简介：: 毕业任务书一、题目套筒工艺及铣床夹具设计二、指导思想和目的要求机械加工工艺与夹具设计是全面地综合运用有关专业课程的理论和实践知识进行加工工艺及夹具结构设计的一次重要实践。通过该毕业设计，综合所学专业知识，熟练的运用机械制造工艺学的基本理论和夹具设计原理的知识，正确的解决一个零件在加工中的定位，夹紧以及合理制定工艺规程等问题的方法，培养编制机械加工工艺规程和机床夹具设计的能力，同时培养分析问题和解决问题的能力，加深理论知识的理解，强化生产实习中的感性认识。设计过程也是理论联系实际的过程，能培养理论联系实际的设计思想，并学会使用手册，查询相关相关资料等，提高分析和解决工程实际问题的独立工作能力，能巩固，加深和扩展有关呢机械加工工艺与夹具方面的知识，为以后的实际工作奠定坚实的基础。三、主要技术指标1. 机械中英文材料 2. 套筒的CAD制图3. 套筒的加工工艺过程综合卡 4. 铣床夹具设计图5. 设计毕业论文四、进度和要求第一阶段：第八学期第1，2周，完成零件CAD制图，撰写开题报告第二阶段：第八学期第3，4周，修改并完成文献综诉与译文，；第三阶段：第八学期第5，6周，分析套筒工艺设计的初步思想；第四阶段：第八学期第7，8周，研读工艺规程设计资料，制定零件加工工艺规程；第五阶段：第八学期第9，10周，铣床夹具设计与计算，绘制制定零件图；第六阶段：第八学期第11，12周，完善铣床夹具设计，画出夹具装配图。第七阶段：第八学期第13，14周，拟定毕业设计论文框架，整理和撰写设计论文，形成终稿，送审，修改，并装订。五、主要参考书及参考资料1 闫光明，侯忠滨，张云鹏。现代制造工艺基础M西安：西北工业大学出版社，2007. 2 狄瑞坤，潘晓弘，樊晓燕。机械制造工程M杭州：浙江大学出版社。2001. 3 薛源顺，机床夹具设计M北京：机械工业出版社，2000 4 许建新，孔宪光，张振明，CAPP技术综述JCAD/CAM与制造业信息化。2002.5 蔡瑾，段国林，李翠玉，李德红，夹具设计技术发展综诉J河北工业大学报， 2002. 6 魏米，吴大春，机械加工工艺路线的拟定J，民营科技，2008. 学生指导教师系主任西北工业大学明德学院本科毕业设计论文 Basic Machining Operations and Cutting Technologyu Basic Machining Operations Machine tools have evolved from the early foot-powered lathes of the Egyptians and John Wilkinsons boring mill. They are designed to provide rigid support for both the workpiece and the cutting tool and can precisely control their relative positions and the velocity of the tool with respect to the workpiece. Basically, in metal cutting, a sharpened wedge-shaped tool removes a rather narrow strip of metal from the surface of a ductile workpiece in the form of a severely deformed chip. The chip is a waste product that is considerably shorter than the workpiece from which it came but with a corresponding increase in thickness of the uncut chip. The geometrical shape of workpiece depends on the shape of the tool and its path during the machining operation. Most machining operations produce parts of differing geometry. If a rough cylindrical workpiece revolves about a central axis and the tool penetrates beneath its surface and travels parallel to the center of rotation, a surface of revolution is produced, and the operation is called turning. If a hollow tube is machined on the inside in a similar manner, the operation is called boring. Producing an external conical surface uniformly varying diameter is called taper turning, if the tool point travels in a path of varying radius, a contoured surface like that of a bowling pin can be produced; or, if the piece is short enough and the support is sufficiently rigid, a contoured surface could be produced by feeding a shaped tool normal to the axis of rotation. Short tapered or cylindrical surfaces could also be contour formed. Flat or plane surfaces are frequently required. They can be generated by radial turning or facing, in which the tool point moves normal to the axis of rotation. In other cases, it is more convenient to hold the workpiece steady and reciprocate the tool across it in a series of straight-line cuts with a crosswise feed increment before each cutting stroke. This operation is called planning and is carried out on a shaper. For larger pieces it is easier to keep the tool stationary and draw the workpiece under it as in planning. The tool is fed at each reciprocation. Contoured surfaces can be produced by using shaped tools. Multiple-edged tools can also be used. Drilling uses a twin-edged fluted tool for holes with depths up to 5 to 10 times the drill diameter. Whether the drill turns or the workpiece rotates, relative motion between the cutting edge and the workpiece is the important factor. In milling operations a rotary cutter with a number of cutting edges engages the workpiece. Which moves slowly with respect to the cutter. Plane or contoured surfaces may be produced, depending on the geometry of the cutter and the type of feed. Horizontal or vertical axes of rotation may be used, and the feed of the workpiece may be in any of the three coordinate directions. u Basic Machine Tools Machine tools are used to produce a part of a specified geometrical shape and precise I size by removing metal from a ductile material in the form of chips. The latter are a waste product and vary from long continuous ribbons of a ductile material such as steel, which are undesirable from a disposal point of view, to easily handled well-broken chips resulting from cast iron. Machine tools perform five basic metal-removal processes: I turning, planning, drilling, milling, and grinding. All other metal-removal processes are modifications of these five basic processes. For example, boring is internal turning; reaming, tapping, and counter boring modify drilled holes and are related to drilling; bobbing and gear cutting are fundamentally milling operations; hack sawing and broaching are a form of planning and honing; lapping, super finishing. Polishing and buffing are variants of grinding or abrasive removal operations. Therefore, there are only four types of basic machine tools, which use cutting tools of specific controllable geometry: 1. lathes, 2. planers, 3. drilling machines, and 4. milling machines. The grinding process forms chips, but the geometry of the abrasive grain is uncontrollable. The amount and rate of material removed by the various machining processes may be I large, as in heavy turning operations, or extremely small, as in lapping or super finishing operations where only the high spots of a surface are removed. A machine tool performs three major functions: 1. it rigidly supports the workpiece or its holder and the cutting tool; 2. it provides relative motion between the workpiece and the cutting tool; 3. it provides a range of feeds and speeds usually ranging from 4 to 32 choices in each case. u Speed and Feeds in Machining Speeds, feeds, and depth of cut are the three major variables for economical machining. Other variables are the work and tool materials, coolant and geometry of the cutting tool. The rate of metal removal and power required for machining depend upon these variables. The depth of cut, feed, and cutting speed are machine settings that must be established in any metal-cutting operation. They all affect the forces, the power, and the rate of metal removal. They can be defined by comparing them to the needle and record of a phonograph. The cutting speed (V) is represented by the velocity of- the record surface relative to the needle in the tone arm at any instant. Feed is represented by the advance of the needle radially inward per revolution, or is the difference in position between two adjacent grooves. The depth of cut is the penetration of the needle into the record or the depth of the grooves. u Turning on Lathe Centers The basic operations performed on an engine lathe are illustrated. Those operations performed on external surfaces with a single point cutting tool are called turning. Except for drilling, reaming, and lapping, the operations on internal surfaces are also performed by a single point cutting tool. All machining operations, including turning and boring, can be classified as roughing, finishing, or semi-finishing. The objective of a roughing operation is to remove the bulk of the material as rapidly and as efficiently as possible, while leaving a small amount of material on the work-piece for the finishing operation. Finishing operations are performed to obtain the final size, shape, and surface finish on the workpiece. Sometimes a semi-finishing operation will precede the finishing operation to leave a small predetermined and uniform amount of stock on the work-piece to be removed by the finishing operation. Generally, longer workpieces are turned while supported on one or two lathe centers. Cone shaped holes, called center holes, which fit the lathe centers are drilled in the ends of the workpiece-usually along the axis of the cylindrical part. The end of the workpiece adjacent to the tailstock is always supported by a tailstock center, while the end near the headstock may be supported by a headstock center or held in a chuck. The headstock end of the workpiece may be held in a four-jaw chuck, or in a type chuck. This method holds the workpiece firmly and transfers the power to the workpiece smoothly; the additional support to the workpiece provided by the chuck lessens the tendency for chatter to occur when cutting. Precise results can be obtained with this method if care is taken to hold the workpiece accurately in the chuck. Very precise results can be obtained by supporting the workpiece between two centers. A lathe dog is clamped to the workpiece; together they are driven by a driver plate mounted on the spindle nose. One end of the Workpiece is mecained;then the workpiece can be turned around in the lathe to machine the other end. The center holes in the workpiece serve as precise locating surfaces as well as bearing surfaces to carry the weight of the workpiece and to resist the cutting forces. After the workpiece has been removed from the lathe for any reason, the center holes will accurately align the workpiece back in the lathe or in another lathe, or in a cylindrical grinding machine. The workpiece must never be held at the headstock end by both a chuck and a lathe center. While at first thought this seems like a quick method of aligning the workpiece in the chuck, this must not be done because it is not possible to press evenly with the jaws against the workpiece while it is also supported by the center. The alignment provided by the center will not be maintained and the pressure of the jaws may damage the center hole, the lathe center, and perhaps even the lathe spindle. Compensating or floating jaw chucks used almost exclusively on high production work provide an exception to the statements made above. These chucks are really work drivers and cannot be used for the same purpose as ordinary three or four-jaw chucks. While very large diameter workpieces are sometimes mounted on two centers, they are preferably held at the headstock end by faceplate jaws to obtain the smooth power transmission; moreover, large lathe dogs that are adequate to transmit the power not generally available, although they can be made as a special. Faceplate jaws are like chuck jaws except that they are mounted on a faceplate, which has less overhang from the spindle bearings than a large chuck would have. u Introduction of Machining Machining as a shape-producing method is the most universally used and the most important of all manufacturing processes. Machining is a shape-producing process in which a power-driven device causes material to be removed in chip form. Most machining is done with equipment that supports both the work piece and cutting tool although in some cases portable equipment is used with unsupported workpiece. Low setup cost for small Quantities. Machining has two applications in manufacturing. For casting, forging, and press working, each specific shape to be produced, even one part, nearly always has a high tooling cost. The shapes that may he produced by welding depend to a large degree on the shapes of raw material that are available. By making use of generally high cost equipment but without special tooling, it is possible, by machining; to start with nearly any form of raw material, so tong as the exterior dimensions are great enough, and produce any desired shape from any material. Therefore .machining is usually the preferred method for producing one or a few parts, even when the design of the part would logically lead to casting, forging or press working if a high quantity were to be produced. Close accuracies, good finishes. The second application for machining is based on the high accuracies and surface finishes possible. Many of the parts machined in low quantities would be produced with lower but acceptable tolerances if produced in high quantities by some other process. On the other hand, many parts are given their general shapes by some high quantity deformation process and machined only on selected surfaces where high accuracies are needed. Internal threads, for example, are seldom produced by any means other than machining and small holes in press worked parts may be machined following the press working operations. u Primary Cutting Parameters The basic tool-work relationship in cutting is adequately described by means of four factors: tool geometry, cutting speed, feed, and depth of cut. The cutting tool must be made of an appropriate material; it must be strong, tough, hard, and wear resistant. The tool s geometry characterized by planes and angles, must be correct for each cutting operation. Cutting speed is the rate at which the work surface passes by the cutting edge. It may be expressed in feet per minute. For efficient machining the cutting speed must be of a magnitude appropriate to the particular work-tool combination. In general, the harder the work material, the slower the speed. Feed is the rate at which the cutting tool advances into the workpiece. Where the workpiece or the tool rotates, feed is measured in inches per revolution. When the tool or the work reciprocates, feed is measured in inches per stroke, Generally, feed varies inversely with cutting speed for otherwise similar conditions. The depth of cut, measured inches is the distance the tool is set into the work. It is the width of the chip in turning or the thickness of the chip in a rectilinear cut. In roughing operations, the depth of cut can be larger than for finishing operations. u The Effect of Changes in Cutting Parameters on Cutting Temperatures In metal cutting operations heat is generated in the primary and secondary deformation zones and these results in a complex temperature distribution throughout the tool, workpiece and chip. A typical set of isotherms is shown in figure where it can be seen that, as could be expected, there is a very large temperature gradient throughout the width of the chip as the workpiece material is sheared in primary deformation and there is a further large temperature in the chip adjacent to the face as the chip is sheared in secondary deformation. This leads to a maximum cutting temperature a short distance up the face from the cutting edge and a small distance into the chip. Since virtually all the work done in metal cutting is converted into heat, it could be expected that factors which increase the power consumed per unit volume of metal removed will increase the cutting temperature. Thus an increase in the rake angle, all other parameters remaining constant, will reduce the power per unit volume of metal removed and the cutting temperatures will reduce. When considering increase in unreformed chip thickness and cutting speed the situation is more complex. An increase in undeformed chip thickness tends to be a scale effect where the amounts of heat which pass to the workpiece, the tool and chip remain in fixed proportions and the changes in cutting temperature tend to be small. Increase in cutting speed; however, reduce the amount of heat which passes into the workpiece and this increase the temperature rise of the chip m primary deformation. Further, the secondary deformation zone tends to be smaller and this has the effect of increasing the temperatures in this zone. Other changes in cutting parameters have virtually no effect on the power consumed per unit volume of metal removed and consequently have virtually no effect on the cutting temperatures. Since it has been shown that even small changes in cutting temperature have a significant effect on tool wear rate it is appropriate to indicate how cutting temperatures can be assessed from cutting data. The most direct and accurate method for measuring temperatures in high -speed-steel cutting tools is that of Wright &. Trent which also yields detailed information on temperature distributions in high-speed-steel cutting tools. The technique is based on the metallographic examination of sectioned high-speed-steel tools which relates microstructure changes to thermal history. Trent has described measurements of cutting temperatures and temperature distributions for high-speed-steel tools when machining a wide range of workpiece materials. This technique has been further developed by using scanning electron microscopy to study fine-scale microstructure changes arising from over tempering of the tempered martens tic matrix of various high-speed-steels. This technique has also been used to study temperature distributions in both high-speed -steel single point turning tools and twist drills. u Wears of Cutting Tool Discounting brittle fracture and edge chipping, which have already been dealt with, tool wear is basically of three types. Flank wear, crater wear, and notch wear. Flank wear occurs on both the major and the minor cutting edges. On the major cutting edge, which is responsible for bulk metal removal, these results in increased cutting forces and higher temperatures which if left unchecked can lead to vibration of the tool and workpiece and a condition where efficient cutting can no longer take place. On the minor cutting edge, which determines workpiece size and surface finish, flank wear can result in an oversized product which has poor surface finish. Under most practical cutting conditions, the tool will fail due to major flank wear before the minor flank wear is sufficiently large to result in the manufacture of an unacceptable component. Because of the stress distribution on the tool face, the frictional stress in the region of sliding contact between the chip and the face is at a maximum at the start of the sliding contact region and is zero at the end. Thus abrasive wear takes place in this region with more wear taking place adjacent to the seizure region than adjacent to the point at which the chip loses contact with the face. This result in localized pitting of the tool face some distance up the face which is usually referred to as catering and which normally has a section in the form of a circular arc. In many respects and for practical cutting conditions, crater wear is a less severe form of wear than flank wear and consequently flank wear is a more common tool failure criterion. However, since various authors have shown that the temperature on the face increases more rapidly with increasing cutting speed than the temperature on the flank, and since the rate of wear of any type is significantly affected by changes in temperature, crater wear usually occurs at high cutting speeds. At the end of the major flank wear land where the tool is in contact with the uncut workpiece surface it is common for the flank wear to be more pronounced than along the rest of the wear land. This is because of localised effects such as a hardened layer on the uncut surface caused by work hardening introduced by a previous cut, an oxide scale, and localised high temperatures resulting from the edge effect. This localised wear is usually referred to as notch wear and occasionally is very severe. Although the presence of the notch will not significantly affect the cutting properties of the tool, the notch is often relatively deep and if cutting were to continue there would be a good chance that the tool would fracture. If any form of progressive wear allowed to continue, dramatically and the tool would fail catastrophically, i. e. the tool would be no longer capable of cutting and, at best, the workpiece would be scrapped whilst, at worst, damage could be caused to the machine tool. For carbide cutting tools and for all types of wear, the tool is said to have reached the end of its useful life long before the onset of catastrophic failure. For high-speed-steel cutting tools, however, where the wear tends to be non-uniform it has been found that the most meaningful and reproducible results can be obtained when the wear is allowed to continue to the onset of catastrophic failure even though, of course, in practice a cutting time far less than that to failure would be used. The onset of catastrophic failure is characterized by one of several phenomena, the most common being a sudden increase in cutting force, the presence of burnished rings on the workpiece, and a significant increase in the noise level. u Mechanism of Surface Finish Production There are basically five mechanisms which contribute to the production of a surface which have been machined. These are:1.The basic geometry of the cutting process. In, for example, single point turning the tool will advance a constant distance axially per revolution of the workpiecc and the resultant surface will have on it, when viewed perpendicularly to the direction of tool feed motion, a series of cusps which will have a basic form which replicates the shape of the tool in cut. 2.The efficiency of the cutting operation. It has already been mentioned that cutting with unstable built-up-edges will produce a surface which contains hard built-up-edge fragments which will result in a degradation of the surface finish. It can also be demonstrated that cutting under adverse conditions such as apply when using large feeds small rake angles and low cutting speeds, besides producing conditions which lead to unstable built-up-edge production, the cutting process itself can become unstable and instead of continuous shear occurring in the shear zone, tearing takes place, discontinuous chips of uneven thickness are produced, and the resultant surface is poor. This situation is particularly noticeable when machining very ductile materials such as copper and aluminum. 3.The stability of the machine tool. Under some combinations of cutting conditions; workpiece size, method of clamping ,and cutting tool rigidity relative to the machine tool structure, instability can be set up in the tool which causes it to vibrate. Under some conditions this vibration will reach and maintain steady amplitude whilst under other conditions the vibration will built up and unless cutting is stopped considerable damage to both the cutting tool and workpiece may occur. This phenomenon is known as chatter and in axial turning is characterized by long pitch helical bands on the workpiece surface and short pitch undulations on the transient machined surface. 4.The effectiveness of removing swarf. In discontinuous chip production machining, such as milling or turning of brittle materials, it is expected that the chip (swarf) will leave the cutting zone either under gravity or with the assistance of a jet of cutting fluid and that they will not influence the cut surface in any way. However, when continuous chip production is evident, unless steps are taken to control the swarf it is likely that it will impinge on the cut surface and mark it. Inevitably, this marking besides looking. 5.The effective clearance angle on the cutting tool. For certain geometries of minor cutting edge relief and clearance angles it is possible to cut on the major cutting edge and burnish on the minor cutting edge. This can produce a good surface finish but, of course, it is strictly a combination of metal cutting and metal forming and is not to be recommended as a practical cutting method. However, due to cutting tool wear, these conditions occasionally arise and lead to a marked change in the surface characteristics. u Limits and Tolerances Machine parts are manufactured so they are interchangeable. In other words, each part of a machine or mechanism is made to a certain size and shape so will fit into any other machine or mechanism of the same type. To make the part interchangeable, each individual part must be made to a size that will fit the mating part in the correct way. It is not only impossible, but also impractical to make many parts to an exact size. This is because machines are not perfect, and the tools become worn. A slight variation from the exact size is always allowed. The amount of this variation depends on the kind of part being manufactured. For examples part might be made 6 in. long with a variation allowed of 0.003 (three-thousandths) in. above and below this size. Therefore, the part could be 5.997 to 6.003 in. and still be the correct size. These are known as the limits. The difference between upper and lower limits is called the tolerance. A tolerance is the total permissible variation in the size of a part. The basic size is that size from which limits of size arc derived by the application of allowances and tolerances. Sometimes the limit is allowed in only one direction. This is known as unilateral tolerance.Unilateral tolerancing is a system of dimensioning where the tolerance (that is variation) is shown in only one direction from the nominal size. Unilateral tolerancing allow the changing of tolerance on a hole or shaft without seriously affecting the fit.When the tolerance is in both directions from the basic size it is known as a bilateral tolerance (plus and minus). Bilateral tolerancing is a system of dimensioning where the tolerance (that is variation) is split and is shown on either side of the nominal size. Limit dimensioning is a system of dimensioning where only the maximum and minimum dimensions arc shown. Thus, the tolerance is the difference between these two dimensions. u Surface Finishing and Dimensional Control Products that have been completed to their proper shape and size frequently require some type of surface finishing to enable them to satisfactorily fulfill their function. In some cases, it is necessary to improve the physical properties of the surface material for resistance to penetration or abrasion. In many manufacturing processes, the product surface is left with dirt .chips, grease, or other harmful material upon it. Assemblies that are made of different materials, or from the same materials processed in different manners, may require some special surface treatment to provide uniformity of appearance. Surface finishing may sometimes become an intermediate step processing. For instance, cleaning and polishing are usually essential before any kind of plating process. Some of the cleaning procedures are also used for improving surface smoothness on mating parts and for removing burrs and sharp corners, which might be harmful in later use. Another important need for surface finishing is for corrosion protection in a variety of: environments. The type of protection procedure will depend largely upon the anticipated exposure, with due consideration to the material being protected and the economic factors involved. Satisfying the above objectives necessitates the use of main surface-finishing methods that involve chemical change of the surface mechanical work affecting surface properties, cleaning by a variety of methods, and the application of protective coatings, organic and metallic. In the early days of engineering, the mating of parts was achieved by machining one part as nearly as possible to the required size, machining the mating part nearly to size, and then completing its machining, continually offering the other part to it, until the desired relationship was obtained. If it was inconvenient to offer one part to the other part during machining, the final work was done at the bench by a fitter, who scraped the mating parts until the desired fit was obtained, the fitter therefore being a fitter in the literal sense. J It is obvious that the two parts would have to remain together, and m the event of one having to be replaced, the fitting would have to be done all over again. In these days, we expect to be able to purchase a replacement for a broken part, and for it to function correctly without the need for scraping and other fitting operations.When one part can be used off the shelf to replace another of the same dimension and material specification, the parts are said to be interchangeable. A system of interchangeability usually lowers the production costs as there is no need for an expensive, fiddling operation, and it benefits the customer in the event of the need to replace worn parts. u Automatic Fixture Design Traditional synchronous grippers for assembly equipment move parts to the gripper centre-line, assuring that the parts will be in a known position after they arc picked from a conveyor or nest. However, in some applications, forcing the part to the centre-line may damage cither the part or equipment. When the part is delicate and a small collision can result in scrap, when its location is fixed by a machine spindle or mould, or when tolerances are tight, it is preferable to make a gripper comply with the position of the part, rather than the other way around. For these tasks, Zaytran Inc. Of Elyria, Ohio, has created the GPN series of non- synchronous, compliant grippers. Because the force and synchronizations systems of the grippers are independent, the synchronization system can be replaced by a precision slide system without affecting gripper force. Gripper sizes range from 51b gripping force and 0.2 in. stroke to 40Glb gripping force and 6in stroke. Grippers Production is characterized by batch-size becoming smaller and smaller and greater variety of products. Assembly, being the last production step, is particularly vulnerable to changes in schedules, batch-sizes, and product design. This situation is forcing many companies to put more effort into extensive rationalization and automation of assembly that was previouslyextensive rationalization and automation of assembly that was previously the case. Although the development of flexible fixtures fell quickly behind the development of flexible handling systems such as industrial robots, there are, nonetheless promising attempts to increase the flexibility of fixtures. The fact that fixtures are the essential product - specific investment of a production system intensifies the economic necessity to make the fixture system more flexible. Fixtures can be divided according to their flexibility into special fixtures, group fixtures, modular fixtures and highly flexible fixtures. Flexible fixtures are characterized by their high adaptability to different workpieces, and by low change-over time and expenditure. There are several steps required to generate a fixture, in which a workpiece is fixed for a production task. The first step is to define the necessary position of the workpiece in the fixture, based on the unmachined or base pan, and the working features. Following this, a combination of stability planes must be selected. These stability planes constitute the fixture configuration in which the workpiece is fixed in the defined position, all the forces or torques are compensated, and the necessary access to the working features is ensured. Finally, the necessary positions of moveable or modular fixture elements must be calculated- adjusted, or assembled, so that the workpiece is firmly fixed in the fixture. Through such a procedure the planning and documentation of the configuration and assembly of fixture can be automated.The configuration task is to generate a combination of stability planes, such that fixture forces in these planes will result in workpiece and fixture stability. This task can be accomplished conventionally, interactively or in a nearly fully automated manner. The advantages of an interactive or automated configuration determination are a systematic fixture design process, a reduction of necessary designers, a shortening of lead time and better match to the working conditions. In short, a significant enhancement of fixture productivity and economy can be achieved.附录2：中文翻译基本加工工序和切削技术机床是从早期的埃及人的脚踏动力车和约翰威尔金森的镗床发展而来的。它们为工件和刀具提供刚性支撑并可以精确控制它们的相对位置和相对速度。基本上讲，金属切削是指一个磨尖的锲形工具从有韧性的工件表面上去除一条很窄的金属。切屑是被废弃的产品，与其它工件相比切屑较短，但对于未切削部分的厚度有一定的增加。工件表面的几何形状取决于刀具的形状以及加工操作过程中刀具的路径。大多数加工工序产生不同几何形状的零件。如果一个粗糙的工件在中心轴上转动并且刀具平行于旋转中心切入工件表面，一个旋转表面就产生了，这种操作称为车削。如果一个空心的管子以同样的方式在内表面加工，这种操作称为镗孔。当均匀地改变直径时便产生了一个圆锥形的外表面，这称为锥度车削。如果刀具接触点以改变半径的方式运动，那么一个外轮廓像球的工件便产生了；或者如果工件足够的短并且支撑是十分刚硬的，那么成型刀具相对于旋转轴正常进给的一个外表面便可产生，短锥形或圆柱形的表面也可形成。平坦的表面是经常需要的，它们可以由刀具接触点相对于旋转轴的径向车削产生。在刨削时对于较大的工件更容易将刀具固定并将工件置于刀具下面。刀具可以往复地进给。成形面可以通过成型刀具加工产生。多刃刀具也能使用。使用双刃槽钻钻深度是钻孔直径5-10倍的孔。不管是钻头旋转还是工件旋转，切削刃与工件之间的相对运动是一个重要因数。在铣削时一个带有许多切削刃的旋转刀具与工件接触，工件相对刀具慢慢运动。平的或成形面根据刀具的几何形状和进给方式可能产生。可以产生横向或纵向轴旋转并且可以在任何三个坐标方向上进给。u 基本机床机床通过从塑性材料上去除屑片来产生出具有特别几何形状和精确尺寸的零件。后者是废弃物，是由塑性材料如钢的长而不断的带状物变化而来，从处理的角度来看，那是没有用处的。很容易处理不好由铸铁产生的破裂的屑片。机床执行五种基本的去除金属的过程：车削，刨削，钻孔，铣削。所有其他的去除金属的过程都是由这五个基本程序修改而来的，举例来说，镗孔是内部车削；铰孔，攻丝和扩孔是进一步加工钻过的孔；齿轮加工是基于铣削操作的。抛光和打磨是磨削和去除磨料工序的变形。因此，只有四种基本类型的机床，使用特别可控制几何形状的切削工具1.车床，2.钻床，3.铣床，4.磨床。磨削过程形成了屑片，但磨粒的几何形状是不可控制的。通过各种加工工序去除材料的数量和速度是巨大的，正如在大型车削加工，或者是极小的如研磨和超精密加工中只有面的高点被除掉。一台机床履行三大职能：1.它支撑工件或夹具和刀具2.它为工件和刀具提供相对运动3.在每一种情况下提供一系列的进给量和一般可达4-32种的速度选择。u 加工速度和进给速度，进给量和切削深度是经济加工的三大变量。其他的量数是攻丝和刀具材料，冷却剂和刀具的几何形状，去除金属的速度和所需要的功率依赖于这些变量。切削深度，进给量和切削速度是任何一个金属加工工序中必须建立的机械参量。它们都影响去除金属的力，功率和速度。切削速度可以定义为在旋转一周时速度记录面相对任何瞬间呈辐射状扩散的针，或是两个相邻沟槽的距离。切削深度是进入的深度和沟槽的深度。u 在车床中心的车削在机动车床上完成的基本操作已被介绍了。那些用单点刀具在外表面的操作称为车削。除了钻孔，铰孔，研磨内部表面的操作也是由单点刀具完成的。所有的加工工序包括车削，镗孔可以被归类为粗加工，精加工或半精加工。精加工是尽可能快而有效的去除大量材料，而工件上留下的一小部分材料用于精加工。精加工为工件获得最后尺寸，形状和表面精度。有时，半精加工为精加工留下预定的一定量的材料，它是先于精加工的。一般来说，较长的工件同时被一个或两个车床中心支撑。锥形孔，所谓的中心孔，两端被钻的工件适于车床中心-通常沿着圆柱形工件的轴线。工件接近为架的那端通常由尾架中心支撑，在靠近主轴承的那端由主轴承中心支撑或由爪盘夹紧。这种方法可以牢固的加紧工件并且能顺利地将力传给工件；由卡盘对工件提供的辅助支撑减少切削时发生的颤振趋势，如果能小心准确地采用卡盘支撑工件的方法，则可以得到精确的结果。在两个中心之间支撑工件可以得到非常精确的结果。工件的一端已被加工，那么工件便可车削了。在车床上加工另一端，中心孔充当精确定位面和承载工件重量和抵制切削力的支撑面。当工件由于任何一原因从车床上移除后，中心孔将准确地使工件回到这个车床上或另一个车床上或一个圆柱磨床上。工件不允许被卡盘和车床中心夹在主轴承上。然而首先想到的是一个快速调整卡盘上工件的方法，但这是不允许的因为在由卡盘夹持的同时也由车床中心支撑是不可能的。由车床中心提供的调整将不能持续并且爪盘的压力会损坏中心孔和车床中心，甚至是车床主轴。浮动的爪盘为上述陈述提供了一个例外，它几乎完全使用在高生产工作上，这些卡盘是真正的工作驱动者并且不为同样的目的如普通的三爪，四爪卡盘使用。而大直径的工件有时装在两个中心，它们最好有由面板夹持在主轴承尾部来顺利得到能量转换；许多车床夹头并不能足量的转换能量，虽然可以作为特殊的能量转换。u 机械加工介绍作为产生形状的一种方法，机械加工是所有制造过程中最普遍使用的而且是最重要的方法。机械加工过程是一个产生形状的过程，在这过程中，驱动装置使工件上的一些材料以切屑的形式被去除。尽管在某些场合，工件无支承情况下，使用移动式装备来实现加工，但大多数的机械加工是通过既支承工件又支承刀具的装备来完成。小批量，低成本。机械加工在制造业上有两个应用。是铸造，锻造和压力工作，产生每一个特殊形状，甚至一个零件，几乎总有较高的模具成本。焊接的形状很大程度上取决于原材料。通过利用总成本高但没有特殊模具的设备，加工是有可能的；从几乎任何形式的原材料开始，只要外部尺寸足够大，由任意材料设计形状。因此加工是首选的方法，当生产一个或几个零件甚至在大批量生产时，零件的设计在逻辑上导致铸造，锻造或冲压制品。高精度，表面精度。机械加工的第二个应用是基于可能的高精度和表面精度的。如果在其他工序中大批量生产，很多低量零件会产生出低的但可接受的公差。另一方面，许多零件由一些大变形过程产生一般的形状，并且只在具有很高精度的选定面加工。举例来说，内线流程是很少产生任何方式以外的其他机械加工并且紧接着压力操作后零件上的小洞可能被加工。u 主要的切削参数在切削时基本工具工作的关系充分描述的方法有4个因素：刀具几何形状，切削速度和切削深度。刀具必须由适当的材料做成；它必须有一定的强度，粗糙度，硬度和抗疲劳度。刀具几何形状由面和角度描述，对每一种切削操作都是正确的。切削速度是指切削刃通过工作面的速度，它已每分钟通过的英尺数表示。对于加工效率，切削速度相对于特殊工作组合必须具有适当规模。一般来讲，工件越硬，速度越小。进给是刀具进入工件的速率。当工件或刀具旋转时，进给量的单位是英寸每转。当刀具或工件往复移动时，进给量的单位是英寸没次，总的来说，在其他相似情况下进给量与切削速度成反比。切削速度用英寸表示，是刀具进入工件的距离表示的，它是指车削时屑片的宽度或是直线切削时屑片的厚度。粗加工时切削深度比精加工的切削深度大。u 切削参数的改变对切削温度的影响在金属切削作业中热量产生于主要和第二变形区而这些结果导致了复杂温度遍布于刀具，工件和屑片。一个典型的等温先如图所示，它可以看出正如预测的，当工件材料经历主要变形，被减切时，有一个非常大温度梯度遍布于屑片的整个宽度。当第二变形区的屑片还有一小段距离就达到了最大温度。因为几乎所有的工作都以金属切削转化为热量而完成，可以预测去除每一单位体积的金属所增加的能量消耗将会提高切削温度。因此在所有其他参数不变，前角变大时，将减少去除每单位体积金属的能量和切削温度。当考虑到增加未形成屑片的厚度和速度，情况就更复杂了。增加切削厚度往往会大大影响热量传给工件，刀具的多少，而且会使屑片停留在一个固定数额，同时切削温度的变化也会很小，可是增加切削速度会减少传递给工件的热量，同时这将增大屑片主要变形的温升。此外，第二变形区是比较小的，在这个变形区会提高温度。切削参数的其他变化几乎不影响去除每单位体积的能量消耗和切削温度。因此已经表明，即使是切削温度的小规模变化对刀具磨损率也有重大影响，从切削数据来估计切削温度是恰当的。检测高速钢工具最直接最准确的方法，特伦特给出了高速钢工具温度分布的详细资料。该技术是基于高速钢刀具的数据检测并与对热历史的微观变化有关。特伦特已经描述了切削温度的测量和加工大范围工件时高速钢工具的温度分布。使用扫描电子显微镜来研究精细尺度微观结构变化，这项技术已得到了进一步发展。这项技术也用于研究高速钢单点车刀和麻花钻的温度分布，u 刀具磨损脆性断裂已经得到了处理，刀具磨损基本上有三个类型。后刀面磨损，边界磨损和前刀面磨损。刀面磨损发生在主切削刃和次切削刃。主切削刃负责去除大量金属，这增加了切削力和温度，如果任其发展会导致刀具和工件的振动，这就再不能高效率地切削了。次切削刃决定工件尺寸和表面精度，后刀面的磨损会导致大量产品出现较差的表面精度。根据实际切削条件，刀具不可用的主要原因在于主刀面先于次刀面的磨损非常大，这导致了一个不可接受部分的产生。因为刀具的应力分布，刚开始滑动时，滑动区域的摩擦力在屑片和面之间达到最大，最后摩擦力便为零。因此磨料磨损发生在这个区域，在屑片与相离处更多的磨损发生在与该区域相邻处，这比相邻于这点的更多。这导致了刀具面的局部点蚀与这面有一定距离，这面通常有一部分是圆弧形的。在许多方面并基于实际切削条件，边界磨损相比后刀面是一个较不严重的磨损，因此刀面磨损是一种较常见磨钝标准。然后，由于各样作者表明，伴随着切削速度的增加面温度的增加量多于刀面的增加量，而由于温度变化严重影响任一类型的磨损率，边界磨损通常发生在较高切削速度的情况下。刀具与未切削面相接触的地方，主刀面磨损的尾部的磨损比沿着剩余磨损面的地方更明显。这是因为局部影响如未切削面是由先前的切削，氧化规模，局部高温所形成的加工硬化而造成的。这个局部磨损一般与边界磨损有关，有时还很严重。虽然出现凹口不会严重影响刀具的切削性能，凹口是往往比较深，如果继续切削刀具很可能断裂。如果任何形式的渐进磨损让其戏剧性的继续存在，刀具将面临灾难性的故障，如刀具再不能切割，在好的情况下，工件报废，最坏时，机械工具可能造成损坏。对于硬质合金刀具和各类型的磨损，在出现灾难性故障之前达到最长使用使用寿命的极限。但对于高速钢切削工具的磨损是不均匀的，目前已发现当磨损继续并甚至出现灾难性故障时，便可得到最有意义的和可以复制的结果，当然在实践中，切削时间远远少于故障时间。发生灾难性故障时会出现几个现象，最常见的是切削力突然增加，工件出现亮环，噪音显著增大。u 表面精整加工机理有五个基本机制对于已加工产品有影响：（1）切削过程的基本几何形状，单点车削刀具将轴向前进一个恒定距离，由此产生的面将在它上面，刀具垂直方向进给运动时，一连串的尖点形成切削刀具的基本形状。（2）切削加工的效率。已经提到不稳定刀瘤将产生含有硬化刀瘤片段的面。这个片段使表面光洁度降低。也能证明在不利切削条件下引用大进给，小前角和低切削速度，除此以外生产条件也会导致不稳积屑瘤产品，切削过程变得不稳定而不是在剪切带连续切削，发生破碎，出现不均匀的间断屑片，表面也不够光滑。当加工韧性材料时这种情况尤其明显。（3）机床的稳定。根据某些组合的切削条件，工件尺寸，夹紧的方法和相对机床结构的刚度，不稳定性是刀具造成的颤动。在一定条件下，这种颤动将达到并保持一定的振幅，而根据其它条件的振动也会产生，除非切割阻止了相当大的损坏不然切削刀具和工件都可能发生颤动。这个现象称为颤振，而轴向车削的特点是工件上有长螺旋带，暂加工面上有短节距起伏。（4）去除切屑的有效性。在间断切屑生产加工中，如脆性材料的铣削和车削，预计无论是由于重力还是切削液，屑片都将离开切削区，任何情况下也不会影响切削面。连续屑片是显而易见的，如果不采取措施来控制切屑，就有可能会影响切削面并留下痕迹。无可避免地，这标志着只能期待。（5）切削刀具的有效后角。对于有某一几何形状的小型切削刃和后角，很有可能在主切削刃切削，在次切削刃打磨。这会产生好的表面精度，但当然这一个严格地金属成形的组合，是不能被推荐为实际的切削方法。但是，由于这些情况偶有发生，刀具磨损会导致表面特性的变化。u 极限与公差机械零件被制造因此它们是可互换的。换句话说，每一种机械零件或装置被制成一定的大小和形状来适用于其它型号的机器。为了使零件具有互换性，每一个零件都做成一个尺寸来用正确的方法与对应的零件相配。这不仅不可能，而且是许多零件都做成一个尺寸是不切实际的。这是因为机器不是完美的，而工具会磨损。相对于正确尺寸的一点偏差通常是允许的。这个偏差的大小依赖于被制零件的种类，比如一个零件可能是6英寸，上下偏差是0003英寸（三千分之一）。因此这个偏差可以是5997英寸到6003英寸之间并仍能保持正确尺寸。这就是偏差。上偏差和下偏差之差即是公差。公差是零件尺寸的最大变化量，基本尺寸是允许变动量和公差范围而衍生的尺寸限制。有时偏差只允许一个方向的变动，它允许公差在孔或轴上变化而不会严重影响配合。当公差在两个方向上都变化时，称为完全偏差（正和负）。完全偏差是分开的，并且在基本尺寸的每一边都会有。而极限尺寸只有最大尺寸和最小尺寸。因此，公差是这两个尺寸之差。u 表面精度和尺寸控制产品已经完成了应有的形状和大小，常常需要某种类型的表面精度是它们能够履行好自己的职能。在某些情况下为了抵抗划破和擦破，提高表面材料的物理性能是必须的。在许多制造工艺中，产品表面留下污垢，屑片，油脂或其它有害物质。由不同材料组成的混合物，不同方式加工的同种材料，可能需要一些特殊的面处理以提供均匀的外观。表面抛光处理有时可能成为一个中间处理程序。举例来说，先于各种电镀工艺，清洁和抛光通常是必不可少的。一些清洗程序也用来改善配合零件的表面光滑度，也为了去除毛边，这些在以后使用中是有害的。表面抛光处理的另一个重要原因是在各种各样的环境中的防腐保护。保护程序的类型主要取决于预期暴露，并充分考虑到材料保护和经济因数。为了满足上述目的，因此必须使用表面抛光的主要方法，表面力学的化学变化影响工作面的性能，用各种方法清洗，保护涂料和有机金属的应用。在早期的工程中，尽量接近的将配合零件加工到所需尺寸，把配合零件加工到相似尺寸然后完成加工，并不断地将其它零件与它相配，直到得到理想的关系。如果在加工时不方便将一个零件另一个零件相配，则最后的工作是由钳工坐在板凳上，刮削配合零件直到理想的配合，因此作为一名钳工字面意为J，显而易见，两个零件仍在一起而M不得不更换，必须再一次去相配合。在这些日子里，我们期望能为坏零件购买一个替代品，而它的功能正常也不需要刮削和其它修改工序。当一个零件能被用来替换另一个同尺寸和同材料规格的零件，这时我们称之为这些零件能互换。互换系统通常可以降低生产成本，为了一个昂贵的操作是没有必要的，这有益于客户在需要时更换磨料零件。u 自动夹具设计装配设备的传统同步夹子有更多的零件与中心线相对，以确保当电弧从传送带回升时能在一个众所周知的地方。然而，在某些应用中，迫使零件与中心线对准，可能会损坏零件和设备。当零件很小并有一些碰撞可导致刮擦，当它的位置被机床主轴或丝杠固定，或公差是很小时，最好使夹子配合零件的位置而不是倒过来。对于这些任务Zaytran公司Elyria已经创造了GPN不同步系列，它与夹持兼容。因为力和夹子的同步系统是独立的，同步系统可以被一个精密的防滑系统取而带之而不影响夹持力。夹子尺寸范围从51b夹持力和0.2英寸冲程到40Gb夹持力和6英寸冲程。夹子产品的特点是批量的规模越来越小并且提供更多元的产品。作为最后一步生产步骤，装配在批量大小和产品设计时特别容易变化。以前在这种情况下，迫使许多企业把更多的精力投入到广泛合理化和自动化装配上。虽然在以灵活处理系统如工业机器人的背景下，弹性夹具的发展在快速下降，但尝试着增加弹性夹具会成为可能。夹具是必需的产品投资，这一事实激化了使夹具更灵活地在经济上的必要性。夹具可以根据它们的灵活性分为单一夹具，组合夹具，模块化夹具，高灵活夹具。灵活夹具的特点是对不同工件的高度适应性，较少的变换时间和较低的价格。在生产任务中工件在夹具里是固定的，固定一个工件有几个必要步骤。第一步要确定工件在夹具上的位置，考虑未加工面和工作特点。在此之后，固定面必须被选定。工件在确定的位置被固定在固定面上，并添加必要的力和力矩，保证获得必要的工作特点。最后，必要的调动位置或组合夹具因素都要考虑，调整或组装，使工件牢牢地固定在夹具上。通过这样一个程序，工序和工序卡片，夹具的装配可自动进行。结构造型任务就是要产生若干稳定平面的组合，这样在这些平面上的各夹紧力将使工件和夹具稳定。按惯例，这个任务可用人-机对话即几乎完全自动化的方式来完成。以人-机对话即以自动化方式确定夹具结构造型的优点是可有组织有规划进行夹具设计，减少所需的设计人员，缩短研究周期和能更好地配置工作条件。简言之，可成功地达到显著提高夹具生产效率和经济效益。附录3 :外文原文Machine design theory The machine design is through designs the new product or improves the old product to meet the human need the application technical science. It involves the project technology each domain, mainly studies the product the size, the shape and the detailed structure basic idea, but also must study the product the personnel which in aspect the and so on manufacture, sale and use question. Carries on each kind of machine design work to be usually called designs the personnel or machine design engineer. The machine design is a creative work. Project engineer not only must have the creativity in the work, but also must in aspect and so on mechanical drawing, kinematics, engineerig material, materials mechanics and machine manufacture technology has the deep elementary knowledge. If front sues, the machine design goal is the production can meet the human need the product. The invention, the discovery and technical knowledge itself certainly not necessarily can bring the advantage to the humanity, only has when they are applied can produce on the product the benefit. Thus, should realize to carries on before the design in a specific product, must first determine whether the people do need this kind of product Must regard as the machine design is the machine design personnel carries on using creative ability the product design, the system analysis and a formulation product manufacture technology good opportunity. Grasps the project elementary knowledge to have to memorize some data and the formula is more important than. The merely service data and the formula is insufficient to the completely decision which makes in a good design needs. On the other hand, should be earnest precisely carries on all operations. For example, even if places wrong a decimal point position, also can cause the correct design to turn wrongly. A good design personnel should dare to propose the new idea, moreover is willing to undertake the certain risk, when the new method is not suitable, use original method. Therefore, designs the personnel to have to have to have the patience, because spends the time and the endeavor certainly cannot guarantee brings successfully. A brand-new design, the request screen abandons obsoletely many, knows very well the method for the people. Because many person of conservativeness, does this certainly is not an easy matter. A mechanical designer should unceasingly explore the improvement existing product the method, should earnestly choose originally, the process confirmation principle of design in this process, with has not unified it after the confirmation new idea. Newly designs itself can have the question occurrence which many flaws and has not been able to expect, only has after these flaws and the question are solved, can manifest new goods come into the market the product superiority. Therefore, a performance superior product is born at the same time, also is following a higher risk. Should emphasize, if designs itself does not request to use the brand-new method, is not unnecessary merely for the goal which transform to use the new method. In the design preliminary stage, should allow to design the personnel fully to display the creativity, not each kind of restraint. Even if has had many impractical ideas, also can in the design early time, namely in front of the plan blueprint is corrected. Only then, only then does not send to stops up the innovation the mentality. Usually, must propose several sets of design proposals, then perform the comparison. Has the possibility very much in the plan which finally designated, has used certain not in plan some ideas which accepts. How does the psychologist frequently discuss causes the machine which the people adapts them to operate. Designs personnels basic responsibility is diligently causes the machine to adapt the people. This certainly is not an easy work, because certainly does not have to all people to say in fact all is the most superior operating area and the operating process. Another important question, project engineer must be able to carry on the exchange and the consultation with other concerned personnel. In the initial stage, designs the personnel to have to carry on the exchange and the consultation on the preliminary design with the administrative personnel, and is approved. This generally is through the oral discussion, the schematic diagram and the writing material carries on. In order to carry on the effective exchange, needs to solve the following problem: (1) designs whether this product truly does need for the people? Whether there is competitive ability (2) does this product compare with other companies existing similar products? (3) produces this kind of product is whether economical? (4) product service is whether convenient? (5) product whether there is sale? Whether may gain? Only has the time to be able to produce the correct answer to above question. But, the product design, the manufacture and the sale only can in carry on to the above question preliminary affirmation answer foundation in. Project engineer also should through the detail drawing and the assembly drawing, carries on the consultation together with the branch of manufacture to the finally design proposal. Usually, can have some problem in the manufacture process. Possibly can request to some components size or the common difference makes some changes, causes the components the production to change easily. But, in the project change must have to pass through designs the personnel to authorize, guaranteed cannot damage the product the function. Sometimes, when in front of product assembly or in the packing foreign shipment experiment only then discovers in the design some kind of flaw. These instances exactly showed the design is a dynamic process. Always has a better method to complete the design work, designs the personnel to be supposed unceasingly diligently, seeks these better method. Recent year, the engineerig material choice already appeared importantly. In addition, the choice process should be to the material continuously the unceasing again appraisal process. The new material unceasingly appears, but some original materials can obtain the quantity possibly can reduce. The environmental pollution, material recycling aspect and so on use, workers health and security frequently can attach the new limiting condition to the choice of material. In order to reduce the weight or saves the energy, possibly can request the use different material. Comes from domestic and international competition, to product service maintenance convenience request enhancement and customers aspect the and so on feedback pressure, can urge the people to carry on to the material reappraises. Because the material does not select when created the product responsibility lawsuit, has already had the profound influence. In addition, the material and between the material processing interdependence is already known by the people clearly. Therefore, in order to can and guarantees the quality in the reasonable cost under the premise to obtain satisfaction the result, project engineer makes engineers all to have earnestly carefully to choose, the determination and the use material. Makes any product the first step of work all is designs. Designs usually may divide into several explicit stages: (a) preliminary design; (b) functional design; (c) production design. In the preliminary design stage, the designer emphatically considered the product should have function. Usually must conceive and consider several plans, then decided this kind of thought is whether feasible; If is feasible, then should makes the further improvement to or several plans. In this stage, the question which only must consider about the choice of material is: Whether has the performance to conform to the request material to be possible to supply the choice; If no, whether has a bigger assurance all permits in the cost and the time in the limit develops one kind of new material.In the functional design and the engineering design stage, needs to make a practical feasible design. Must draw up the quite complete blueprint in this stage, chooses and determines each kind of components the material. Usually must make the prototype or the working model, and carries on the experiment to it, the appraisal product function, the reliability, the outward appearance and the service maintenance and so on. Although this kind of experiment possibly can indicate, enters in the product to the production base in front of, should replace certain materials, but, absolutely cannot this point take not earnestly chooses the material the excuse. Should unify the product the function, earnestly carefully considers the product the outward appearance, the cost and the reliability. Has the achievement very much the company when manufacture all prototypes, selects the material should the material which uses with its production in be same, and uses the similar manufacture technology as far as possible. Like this has the advantage very much to the company. The function complete prototype if cannot act according to the anticipated sales volume economically to make, or is prototypical and the official production installment has in the quality and the reliable aspect is very greatly different, then this kind of prototype does not have the great value. Project engineer is best can completely complete the material in this stage the analysis, the choice and the determination work, but is not remains it to the production design stage does. Because, is carries on in the production design stage material replacement by other people, these people are inferior to project engineer to the product all functions understanding. In the production design stage, is should completely determine with the material related main question the material, causes them to adapt with the existing equipment, can use the existing equipment economically to carry on the processing, moreover the material quantity can quite be easy to guarantee the supply. In the manufacture process, inevitably can appear to uses the material to make some changes the situation. The experience indicated that, may use certain cheap materials to take the substitute. However, in the majority situation, in will carry on the production later to change the material to have in to start before the production to change the price which the material will spend to have to be higher than. Completes the choice of material work in the design stage, may avoid the most such situations. Started after the production manufacture to appear has been possible to supply the use the new material is replaces the material the most common reason. Certainly, these new materials possibly reduce the cost, the improvement product performance. But, must carry on the earnest appraisal to the new material, g

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