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数控电火花成型机床设计【4张CAD图纸+毕业答辩论文】

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摘要………………………………………………………………………………… i

Abstract…………………………………………………………………………… ii

1 绪论……………………………………………………………………………… 1

1.1电火花加工的基本原理…………………………………………………… 1

1.2 电火花加工的特点和适用范围…………………………………………… 2

2 机床总体设计…………………………………………………………………… 5

2.1 设计总体方案……………………………………………………………… 5

2.1.1 功能设计……………………………………………………………… 5

2.1.2 结构设计……………………………………………………………… 7

2.1.3 性能设计……………………………………………………………… 7

3 机械系统的设计………………………………………………………………… 10

3.1 脉冲当量的选择…………………………………………………………… 10

3.2 传动比的选择……………………………………………………………… 10

3.3 滚珠丝杆的选型和校核…………………………………………………… 11

3.4 步进电机的选用…………………………………………………………… 13

3.5同步带的设计选用………………………………………………………… 15

3.6 回转工作台的设计………………………………………………………… 18

3.6.1 工作原理……………………………………………………………… 18

3.6.2 蜗轮蜗杆的设计计算………………………………………………… 20

3.6.3 齿轮的设计计算与校核……………………………………………… 23

结论………………………………………………………………………………… 30

致谢………………………………………………………………………………… 31

参考文献…………………………………………………………………………… 32

摘要

电火花加工技术是先进生产制造技术中的一个重要组成部分，是机械制造业中最广泛采用的机械切削和磨削加工的重要补充和发展。其最大特点是：工具和工件是非接触加工，加工中没有宏观的，因而可以用软的铜、石墨等材料加工任何硬度和强度的难加工金属材料；可以加工非常复杂的立体成型表面；可以加工低刚度、薄壁、深孔、微细孔等特殊精密零件。在各类模具制造业中，电火花加工技术是必不可少的关键技术。由于电火花加工技术是机电一体化技术，是机械、电工、电子、数控、自动控制、计算机应用等多门学科、专业知识的综合运用。

我的设计课题是DK7132数控电火花穿孔成型加工机床。DK为数控电加工机床，71为电火花穿孔，成型加工机床。32为机床工作台宽度。

此次设计包括机床的总体机构设计，主轴运动的设计，横向进给，纵向进給，回转方向运动的设计。其中还包括带轮的强度计算，滚珠丝杆校核，轴承寿命的验算。

关键词：数控电火花加工主轴运动横向进给纵向进给步进电机

Abstract

The technology of electrical-discharge machining is an important part of advanced manufacture technology. And it is also an important complementarity and development of machine cutting and grinding machining in machine manufacture. The characteristic of electrical-discharge machining is that the tools and the work piece do not contact. There is no macroscopical cutting force. So we can use the material, such as soft copper and graphite, to machining metal materials regardless any rigidity and intension. The process is suited to the complicated solid molding surface. Electrical-discharge machining is also used for special precise part. In various tool making, the technology of electrical-discharge machining is the necessary key technology. Because the technology of electrical-discharge machining is the technology of mechatronics, and it is the integrate application of many subjects and professional knowledge , for example mechanism、electrician、electron、numerical control、auto control and computer application.

My design subject is DK7132 numerical control electrical-discharge perforation molding machining tool. DK means numerical control machining tool. 71 means electrical-discharge perforation molding machining tool. 32 means the width of tool’s worktable.

The design contains collectivity distribution design, principle axis design, landscape orientation feed design, portrait feed design, circumgyrate worktable design. It still includes intension calculation of gear wheel, the checking of ball bearing pole and the calculation of axis gearing life-span. The controlling system part contains the circuit of step-by-step electromotor control and the circuit of pulse electrical source. This part is the most important part of numerical control electrical-discharge machining tool, and it is very hard for me. The design of step-by-step electromotor control includes hardware circuit design and software system design. It explains the enlarging of CMOS chip and the design of keyboard display interface. The circuit of pulse electrical source uses high and low voltage pulse electrical source. The circuit is composed by transistor and unattached elements, it exports high and low voltage pulse, which can apply with two electrical-discharge interval and improve productivity.

Key words: Numerical control electrical-discharge machining, principle axis motion , step-by-step electromotor, pulse electrical source.

1 绪论

1.1电火花加工的基本原理

电火花加工的原理是基于工具和工件（正、负电极）之间脉冲性火花放电时的电腐蚀现象来蚀除多余的金属，以达到对零件的尺寸、形状及表面质量预定的加工要求。电腐蚀现象早在20世纪初就被人们发现，例如在插头或电器开关触点开、闭时，往往产生火花而把接触表面烧毛，腐蚀成粗糙不平的凹坑而逐渐损坏。长期以来，电腐蚀一直被人们认为是一种有害的现象，人们不断地研究电腐蚀的原因并设法减轻和避免电腐蚀的发生。但事物都是一分为二的，只要掌握规律，在一定条件下可以把坏事转成好事，把有害变为有用。1940年前后，前苏联科学院电工研究所拉扎连柯夫妇的研究结果表明，电火花腐蚀的主要原因是：电火花放电时火花通道中瞬时产生大量的热，达到很高的温度，足以使任何金属材料局部熔化、汽化而被蚀除掉，形成放电凹坑。这样，热门在研究抗电腐蚀办法的同时，开始研究利用电腐蚀现象对金属材料进行尺寸加工，终于在1943年拉扎连柯夫妇研制出利用电容器反复充电放电原理的世界上第一台使用化的电火花加工装置。

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内容简介：: 1 毕业设计（论文）任务书系部机械工程系指导教师李兆铨职称高工学生姓名甄立专业班级 05gb 机制 1 学号 0515011109 设计题目数控电火花成型机床设计设计内容目标和要求一设计内容 1 测绘一个在电火花成型机床上加工的典型零件，绘制零件工作图、工序图。 2 进行数控电火花机床方案分析，设计机床总图。机床结构可参考立式数控铣床的相应结构部件，但应考虑两者间的差异。 3 设计该机床的一个重要部分，如主轴头、工作台、主轴头进给机构等，画出该部件的装配图和主要零件（如主轴、主轴套、工作台、床身、立柱等） 3 张以上工作图。 4 撰写设计说明书。二设计要求 1 设计必须独立完成，要有创造性，不要照抄照搬实习现场的工艺、工装、设备等。 2 设计绘图工作总量一般不少于 2.5A0，其中用计算机绘图不少于一张 A1，但不超过总绘图量的一半。 3 说明书的内容应是围绕本人设计的内容进行分析、计算和论证，不要抄书。说明书内容一般不少于 25 页，建议写出英文摘要。 4 其它有关事项按院、系有关规定执行。三参考资料教材：数控机床特种加工机械工程手册（第二版）第 8、 9 卷机械工业出版社指导教师签名： 2009 年 1 月 10 日系部审核此表由指导教师填写由所在系部审核 nts 2-1 毕业设计（论文）学生开题报告课题名称数控电火花成型机床设计课题来源生产实践课题类型 AX 指导教师 XXX 学生姓名 XXXXX 学号 XXX 专业班级 XXXX 本课题的研究现状、研究目的及意义电火花加工是一种直接利用电能和热能进行加工的新工艺。这一技术已广泛应用于加工淬火钢，不锈钢、硬质合金等难加工材料；用于加工模具等具有复杂表面的零件，已成为切削加工的重要补充和发展。我们的设计的数控电火花加工机床是一个改进设计，我们设计的横向纵向进给系统是用步进电机控制的，还增加了回转工作台，扩大加工范围。提高生产效率。我们这次毕业设计是对大学四年专业知识的综合运用。通过这次设计，更好的掌握了专业知识，对其也有更深入的理解，这对我们将来的工作、学习都是一个莫大的帮助，我们受益匪浅。课题类型：（ 1） A 工程实践型； B 理论研究型； C 科研装置研制型； D 计算机软件型； E 综合应用型（ 2） X 真实课题； Y 模拟课题；（ 1）、（ 2）均要填，如 AY、 BX 等。 nts 2-2 本课题的研究内容我们主要对数控电火花加工机床主轴运动，横向进给运动。在原有加工范围的基础上，我们进行了改进设计，我们进行了回转运动的设计我们进行 DK7132 数控电火花穿孔成型加工机床总体方案及控制系统设计。对步进电机控制电路和脉冲电源电路进行了设计。。本课题研究的实施方案、进度安排 2009.3.16 - 3.20 发任务书、收集资料、写开题报告。 2009.3.23 - 3.27 完成开题报告。 2009.3.30 - .17 制定设计方案、设计、计算。 2009.4.20 - .15 绘制设计方案、设计、计算。 2009 4 月底中期检查 2009.5.18 - 5.29 撰写毕业设计说明书。 2009.6.01 6.05 毕业设计答辩及整理文摘。 nts 2-3 已查阅的主要参考文献 1. 中国机械工程学会中国机械设计大典编委会。中国机械设计大典（ 4）。江西：江西科学技术出版社， 2002 2. 清华大学曹金榜、易锡麟、张玉峰、陈养田、张春编。机床主轴变速箱设计指导。北京：机械工业出版社， 1987 3. 华东纺织工学院、哈尔滨工业大学、天津大学编。机械设计图册。上海：上海科学技术出版社， 1979 4. 吴振彪主编。机电综合设计指导。北京：中国人民大学出版社， 2000 5. 顾熙棠、迟建山、胡宝珍主编。金属切削机床（下册）。上海：上海科学技术出版社， 2000 6. 张学仁主编。数控电火花线切割加工技术。哈尔滨：哈尔滨工业大学出版社， 2000 7. 赵万生主编。电火花加工技术。哈尔滨：哈尔滨工业大学出版社， 2000 8. 李忠文编著。电火花机和线切割机编程与机电控制。北京：化学工业出版社工业装备与信息工程出版中心， 2004 9. 邓星钟主编。机电传动控制（第三版）。武汉：华中科技大学出版社， 2003 10. 秦曾煌主编。电工学下册电子技术（第五版）。北京：高等教育出版社， 1999 指导教师意见指导教师签名：年月日 nts 3 毕业设计（论文）学生申请答辩表课题名称数控电火花成型机床设计指导教师（职称）李兆铨（高工）申请理由毕业设计任务已完成，说明书已编好。学生所在系部机械工程系专业班级 05gb 机制 1 学号 0515011109 学生签名：日期：毕业设计（论文）指导教师评审表序号评分项目（理工科、管理类）评分项目 (文科 ) 满分评分 1 工作量外文翻译 15 2 文献阅读与外文翻译文献阅读与文献综述 10 3 技术水平与实际能力创新能力与学术水平 25 4 研究成果基础理论与专业知识论证能力 25 5 文字表达文字表达 10 6 学习态度与规范要求学习态度与规范要求 15 总分 100 评语（是否同意参加答辩）指导教师签名：另附毕业设计（论文）指导记录册年月日 nts 4 毕业设计（论文）评阅人评审表学生姓名甄立专业班级 05gb 机制 1 学号 0515011109 设计（论文）题目数控电火花成型机床设计评阅人评阅人职称序号评分项目（理工科、管理类）评分项目 (文科 ) 满分评分 1 工作量外文翻译 15 2 文献阅读与外文翻译文献阅读与文献综述 10 3 技术水平与实际能力创新能力与学术水平 25 4 研究成果基础理论与专业知识论证能力 25 5 文字表达文字表达 10 6 学习态度与规范要求学习态度与规范要求 15 总分 100 评语评阅人签名：年月日 nts 5 毕业设计（论文）答辩表学生姓名甄立专业班级 05gb 机制 1 学号 0515011109 设计（论文）题目数控电火花成型机床设计序号评审项目指标满分评分 1 报告内容思路清新；语言表达准确，概念清楚，论点正确；实验方法科学，分析归纳合理；结论有应用价值。 40 2 报告过程准备工作充分 ,时间符合要求。 10 3 创新对前人工作有改进或突破，或有独特见解。 10 4 答辩回答问题有理论依据，基本概念清楚。主要问题回答准确，深入。 40 总分 100 答辩组评语答辩组组长（签字）：年月日答辩委员会意见答辩委员会负责人（签字）：年月日 nts 6-1 毕业设计（论文）答辩记录表学生姓名甄立专业班级 05gb 机制 1 学号 0515011109 设计（论文）题目数控电火花成型机床设计答辩时间答辩地点答辩委员会名单朱森酉、李兆铨、王海涛、蒋小盼问题 1 提问人：王海涛问题：数控电火花机床中步进电机的脉冲当量如何得取回答（要点）：因为机床定位精度设计要求是 0.01mm,而脉冲当量必须高于这个精度，故而初选 0.005mm/脉冲。而在后来的设计中，运用公式 i= 问题 2 提问人：问题：回答（要点）：问题 3 提问人：问题：回答（要点）：记录人签名（不足加附页） nts 6-2 问题 4 提问人：问题：回答（要点）：问题 5 提问人：问题：回答（要点）：问题 6 提问人：问题：回答（要点）：问题 7 提问人：问题：回答（要点）：问题 8 提问人：问题：回答（要点）：记录人签名 nts 7 毕业设计（论文）成绩评定总表学生姓名：甄立专业班级： 05gb 机制 1 毕业设计（论文）题目：数控电火花成型机床设计注：成绩评定由指导教师、评阅教师和答辩组分别给分 (以百分记 )，最后按“优 (90-100)”、“良 (80-89)”、“中 (70-79)”、“及格 (60-69)”、“不及格 (60 以下 )”评定等级。其中，指导教师评定成绩占 40%，评阅人评定成绩占 20%，答辩组评定成绩占 40%。成绩类别成绩评定指导教师评定成绩评阅人评定成绩答辩组评定成绩总评成绩 40%+ 20%+ 40% 评定等级 nts 毕业设计（论文）数控电火花成型机床设计学生姓名：甄立学号： 0515011109 所在系部：机械工程系专业班级： 05 机制一班指导教师：李兆铨高工日期：二九年六月： nts The design of numerical control electrical-discharge perforation molding machining tool By Zhen Li June 2009 nts 毕业设计（论文）英文文献翻译学生姓名：甄立学号： 0515011109 所在系部：机械工程系专业班级： 05 机制一班指导教师：李兆铨高工日期：二九年六月 nts - i - 摘要电火花加工技术是先进生产制造技术中的一个重要组成部分，是机械制造业中最广泛采用的机械切削和磨削加工的重要补充和发展。其最大特点是：工具和工件是非接触加工，加工中没有宏观的，因而可以用软的铜、石墨等材料加工任何硬度和强度的难加工金属材料；可以加工非常复杂的立体成型表面；可以加工低刚度、薄壁、深孔、微细孔等特殊精密零件。在各类模具制造业中，电火花加工技术是必不可少的关键技术。由于电火花加工技术是机电一体化技术，是机械、电工、电子、数控、自动控制、计算机应用等多门学科、专业知识的综合运用。我的设计课题是 DK7132 数控电火花穿孔成型加工机床。 DK 为数控电加工机床， 71 为电火花穿孔，成型加工机床。 32 为机床工作台宽度。此次设计包括机床的总体机构设计，主轴运动的设计，横向进给，纵向进給，回转方向运动的设计。其中还包括带轮的强度计算，滚珠丝杆校核，轴承寿命的验算。关键词：数控电火花加工主轴运动横向进给纵向进给步进电机 nts - ii - Abstract The technology of electrical-discharge machining is an important part of advanced manufacture technology. And it is also an important complementarity and development of machine cutting and grinding machining in machine manufacture. The characteristic of electrical-discharge machining is that the tools and the work piece do not contact. There is no macroscopical cutting force. So we can use the material, such as soft copper and graphite, to machining metal materials regardless any rigidity and intension. The process is suited to the complicated solid molding surface. Electrical-discharge machining is also used for special precise part. In various tool making, the technology of electrical-discharge machining is the necessary key technology. Because the technology of electrical-discharge machining is the technology of mechatronics, and it is the integrate application of many subjects and professional knowledge , for example mechanism、 electrician、 electron、 numerical control、 auto control and computer application. My design subject is DK7132 numerical control electrical-discharge perforation molding machining tool. DK means numerical control machining tool. 71 means electrical-discharge perforation molding machining tool. 32 means the width of tools worktable. The design contains collectivity distribution design, principle axis design, landscape orientation feed design, portrait feed design, circumgyrate worktable design. It still includes intension calculation of gear wheel, the checking of ball bearing pole and the calculation of axis gearing life-span. The controlling system part contains the circuit of step-by-step electromotor control and the circuit of pulse electrical source. This part is the most important part of numerical control electrical-discharge machining tool, and it is very hard for me. The design of step-by-step electromotor nts - iii - control includes hardware circuit design and software system design. It explains the enlarging of CMOS chip and the design of keyboard display interface. The circuit of pulse electrical source uses high and low voltage pulse electrical source. The circuit is composed by transistor and unattached elements, it exports high and low voltage pulse, which can apply with two electrical-discharge interval and improve productivity. Key words: Numerical control electrical-discharge machining, principle axis motion , step-by-step electromotor, pulse electrical source. ntsPage 1 of 12 Electrical-Discharge Machining 1. Electrical-discharge Machining Electrical-discharge machining (EDM),or spark machining, as it is also called, removes material with repetitive spark discharges from a pulsating DC power supply, with a dielectric flowing between the work piece and the tool. The principle of the EDM process is illustrated by the simplified diagram. The tool is mounted on the chuck attached to the machine spindle whose motion is controlled by a servo-controlled feed drive. The workpiece is placed in a tank filled with a dielectric fluid; a depth of at least 50mm over the work surface is maintained to eliminate the risk of fire. The tool and workpiece are connected to a pulsating DC power supply. Dielectric fluid is circulated under pressure by a pump, usually through a hole or holes in the tool electrode. A spark gap of about 0.025 to 0.05mm is maintained by the servomotor. In power supplies for EDM the input power is first converted into continuous DC power by conventional solid-state rectifiers. The flow of this DC power is then controlled by a bank of power transistors which are switched by a digital multivibrator oscillator circuit. The high-power pluses output is then applied to the tools and work piece to produce the sparks responsible for material removal. Each spark generates a localized high temperature on the order of 12000 in its immediate vicinity. This heat caused part of the surrounding dielectric fluid to evaporate; it also melts and vaporizes the metal to form a small crater on the work surface. Since the spark always occurs between the points of the tool and work piece that are closest together, the high spots of the work are gradually eroded, and the form of the tool is reproduced on the work .The condensed metal globules, formed during the process, are carried away by the flowing dielectric fluid. As the metal is eroded, the tool is fed toward the work piece by a servo-controlled feed mechanism. Each pulse in the EDM cycle lasts for only a few microseconds. Repeated pulses, ntsPage 2 of 12 at rates up to 100000 per second, result in uniform erosion of material from the work piece and from the electrode. As the process progressed, the electrode is advanced by the servo drive toward the work piece to maintain a constant gap distance until the final cavity is produced. Application Electrical-discharge machining can be used for all electrically conducting materials regardless of hardness. The process is most suited to the sinking of irregularly shaped holes, slots, and cavities. Fragile work pieces can be machined without breakage. Holes can be of various shapes and can be produced at shallow angles in curved surfaces without problems of tool wander. The EDM process finds greatest application at present in toolmarking, particularly in the manufacture of press tools, extrusion dies, forging dies, and molds. Graphite electrodes produced by copy milling from patterns are often used. A great advantage of EDM is that the tool or die can be machined after it is hardened and hence great accuracy can be achieved. Tools of cemented carbide can be machined after final sintering, which eliminates the need for an intermediate partial sintering stage, thus eliminating the inaccuracies resulting from final sintering after holes, slots, and so on, are machined. Electrical-discharge machining can be used effectively to drill small high-aspect-ratio holes. Diameters as small as 0.3mm in material 20mm or more in thickness can be readily achieved. With efficient flushing, holes with aspect ratios as high as 100:1 have been produced. The process has been used successfully to produce very-small-diameter holes in hardened fuel-injector nozzles. Varying numbers of holes in a precise patten can be drilled around the injector tip. 2 Numerical Control Numerical control (NC) is a method of controlling the movements of machine components by directly inserting coded instructions in the form of numerical data (numbers and data) into the system. The system automatically interprets these data and converts it to output signals. These signals, in turn control various machine ntsPage 3 of 12 components, such as turning spindles on and off, changing tools, moving the workpiece or the tools along specific paths, and turning cutting fluids on and off. In order to appreciate the importance of numerical control of machines, lets briefly review how a process such as machining has been carried out traditionally. After studying the working drawing of a part, the operator sets up the appropriate process parameters(such as cutting speed, feed, depth of cut, cutting fluid, and so on), determines the sequence of operations to be performed, clamps the workpiece in a workholding device such as a chuck or collet, and proceeds to make the part. Depending on part shape and the dimensional accuracy specified, this approach usually requires skilled operators. Furthermore, the machining procedure followed may depend on the particular operator, and because of the possibilities of human error, the parts produced by the same operator may not all be identical. Part quality may thus depend on the particular operator or even the same operator on different days or different hours of the day. Because of our increased concern with product quality and reducing manufacturing costs, such variability and its effects on product quality are no longer acceptable. This situation can be eliminated by numerical control of the machining operation. We can illustrate the importance of numerical control by the following example. Assume that holes have to be drilled on a part in the positions shown in the picture. In the traditional manual method of machining this part, the operator positions the drill with respect to the workpiece, using as reference points any of the three method shown. The operator then proceeds to drill these holes. Lets assume that 100 parts, having exactly the same shape and dimensional accuracy, have to be drilled. Obviously, this operation is going to be tedious because the operator has to go through the same motions again and again. Moreover, the probability is high that, for various reasons, some of the paths machined will be different from others. Lets further assume that during this production run, the order for these paths is changed, so that 10 of the paths now require holes in different positions. The machinist now has to reset the machine, which will be time consuming and subject to error. Such operations can be performed easily by numerical control machines that are capable of producing ntsPage 4 of 12 parts repeatedly and accurately and of handling different parts by simply loading different part programs. In numerical control, data concerning all aspects of the machining operation, such as locations, speeds, feeds, and cutting fluid, are stored on magnetic tape ,cassetts, floppy or hard disks, or paper or plastic (Mylar, which is a thermoplastic polyester) tape. Data are stored on punched 25mm wide paper or plastic tape, as originally developed and still used. The concept of NC control is that holes in the tape represent specific information in the form of alphanumeric codes. The presence (on) or absence (off) of these holes is read by sensing devices in the control panel, which then actuate relays and other devices (called hard-wired controls). These devices control various mechanical and electrical systems in the machine. This method eliminated manual setting of machine positions and tool paths or the use of templates and other mechanical guides and devices. Complex operations, such as turning a part having various contours and die sinking in a milling machine, can be carried out. Numerical control has had a major impact on all aspects of manufacturing operations. It is a widely applied technology, particularly in the following areas: a) Machining centers. b) Milling, turning, boring, drilling, and grinding. c) Electrical-discharge, laser-beam, and electron-beam machining. d) Water-jet cutting. e) Punching and nibbling. f) Pipe bending and metal spinning. g) Spot welding and other welding and cutting operation. h) Assembly operations. Numerical control machines are now used extensively in small-and-medium-quantity (typically 500 parts or less) of a wide variety of parts in small shops and large manufacture facilities. Older machines can be retrofitted with numerical control. Advantages and Limitations Numerical control has the following advantages over conventional method of machine control: ntsPage 5 of 12 1. Flexibility of operation and ability to produce complex shapes with good dimensional accuracy, repeatability, reduced scrap loss, and high production rates, productivity, and product quality. 2. Tooling costs are reduced, since templates and other fixtures are not required. 3. Machine adjustments are easy to make with minicomputer and digital readout. 4. More operations can be performed with each setup, and less lead time for setup and machining is required compared to conventional methods. Design changes are facilitated, and inventory is reduced. 5. Programs can be prepared rapidly and can be recalled at any time utilizing microprocessors. Less paperwork is involved. 5. Faster prototype production is possible 6. Required operator skill is less, and the operator has more time to attend to other tasks in the work area. The major limitations of NC are the relatively high cost of the equipment and the need for programming and special maintenance, requiring trained personal. Because NC machines are complex systems, breakdowns can be very costly, so preventive maintenance is essential. However, these limitations are often easily outweighed by the overall economic advantages of NC. 3 Scope of CAD/CAM Computer-aided design is the use of computer systems to facilitate the creation, modification, analysis, and optimization of a design. In this context the term computer system means a combination of hardware and software. Computer-aided manufacturing is the use of a computer system to plan, manage, and control the operation of a manufacturing plant. An appreciation of the scope of CAD/CAM can be obtained by considering the stages that must be completed in the design and manufacture of a product, as illustrate by the product cycle shown. The inner loop of this figure includes the various steps in the product cycle and outer loop show some of ntsPage 6 of 12 the functions of CAD/CAM superimposed the product cycle. Based on market and customer requirements, a product is conceived, which may well be a modification of previous products. This product is then designed in detail, including any required design analysis, and drawings and parts lists are prepared. Subsequently, the various components and assemblies are planned for production, which involves the selection of sequences of processes and machine tools and the estimation of cycle times, together with the determination of process parameters, such as feeds and speeds. When the product is in production, scheduling and control of manufacture take place, and the order and timing of each manufacturing step for each component and assembly is determined to meet an overall manufacturing schedule. The actual manufacturing and control of product quality then takes place according to the schedule and the final products are delivered to the customers. Computer-based procedures have been or are being developed to facilitate each of these stages in the product cycle. Computer-aided design and drafting techniques have been developed. These allow a geometric model of the product and its components to be created in the computer. This model can then be analyzed using specialized software packages, such as those for finite element stress analysis, mechanisms design, and so on. Subsequently, drawings and parts lists can be produced with computer-aided drafting software and plotters. Computer-aided process-planning systems, including the preparation of NC programs, are available that produce work plans, estimates, and manufacturing instruction automatically from geometric descriptions of the components and assemblies. For scheduling and production control, large amounts of data and numerous relatively simple calculations must be carried out. One example is the determination of order quantities by subtracting stock levels from forecasts of the number of items required during a particular manufacturing period. Many commercial software packages are available for scheduling, inventory control, and shop floor control, including materials requirements planning (MRP) system. At the shop floor levels computers are used extensively for the control and monitoring of individual machines. ntsPage 7 of 12 There is a difference in the time scale required for processing data and the issuing of instruction for these various applications of computers in the product cycle. For example, design and process-planning functions are carried out once for each new product and the time scale required is on the order of weeks to years for the completion of the whole task. Scheduling and production controls tasks will be repeated once every production period (usually one week) throughout the year. A t the machine-control level instructions must be issued continually with a time scale of micro-or nanoseconds in many cases. One of the major objectives of CAM is the integration of the various activities in the product cycle into one unified system, in which data is transferred from one function to another automatically. This leads to the concept of computer-integrated manufacture (CIM), with the final objective being the “paperless” factory. Several developments have taken place, but no totally integrated CIM systems have yet been achieved. Since the design and process-planning function are carried out once in the product cycle, these are the most suitable functions for integration. This integration is particular desirable because the geometric data generated during the design process is one of the basic inputs used by process planning when determining appropriate manufacturing sequences and work plans. Consequently, various activities in design and process planning can share a common design and manufacturing data base. With such a system ,geometric models of the products and components are created during the design process. This data is then accessed by various downstream activities, including NC programming, process planning, and robot programming. The programs and work plans generated by these activities are also added to the data base. Production control and inventory control programs can then access the work plans, time estimate, and parts lists (bill of material file), in preparing the manufacturing schedules, for example. ntsPage 8 of 12 电火花加工技术 1电火花加工电火花加工（ EDM），顾名思义，它是通过脉冲直流电源不断产生火花放电来去除工件材料的，且在工件与工具之间有绝缘液体介质。电火花加工的工作原理如简图所示。工具夹在卡盘上，卡盘与由伺服进给系统控制的主轴相连。工件放在充满绝缘液体介质的工作槽中。在工作表面至少要维持 50mm 的距离，是为了消除火灾的隐患。工具和工件与脉冲电源的两输出端相连。绝缘液体介质通过工具电极的小孔，经油泵加压，强迫循环的。伺服系统控制电火花间隙为 0.025-0.05mm。电火花加工的电源首先是将输入的电源通过晶体整流管转化为直流电源，直流电源又受到通过数字多谐振荡电路转换来的晶体管的控制。输出的高频脉冲作用到工具和工件上，产生电火花来去除工件材料。每个电火花瞬间产生高达 12000的局部高温，这些热量使部分绝缘液体介质蒸发，也使工件表面蚀除一小部分金属，在工件表面形成一个小凹坑。由于在极间距离相对最近击穿放电，工件表面逐渐被蚀除掉，工具的形状复制到工件上了。在此过程中形成的一些浓缩的金属小屑被流动的绝缘液体介质排除出去。随着金属被蚀除掉，工具电极通过饲服进给系统控制向工件进给。电火花加工中每个脉冲延续的时间只有几个微秒，经过不断的重复放电，工件和工具电极有一样的腐蚀形状。随着电火花加工的进行，工具电极不断向工件进给，直到加工完成，一直保持一定的放电间隙。应用电火花加工能加工任何硬度的导电材料，且大部分用于加工不规则的孔，槽和型腔。那些刚度低的工件也可以加工。电火花加工还可加工出各种形状的孔以及曲面上角度很小的孔，且不存在工具漂移的问题。目前，电火花加工极广泛地用于模具制造，特别是压力机模具，挤压模，锻模和铸模等。通过模型复制制造出来的石墨电极也经常使用。电火花加工的优点就是工具在硬化处理后仍能加工出来，因此能达到很高的ntsPage 9 of 12 精度。硬质合金的工具在烧结后也能加工出来。电火花加工能有效的加工出又小又深的孔。已经在直径只有 0.3mm 的材料上钻出深 20mm 甚至更深的孔。经过有效的吹氮脱气，可以加工出宽径比为 100：1 的孔。电火花加工已成功地用于已淬硬喷油嘴的极小孔的加工，能在喷油嘴周围精确的钻出大量的孔。 2数字控制数控是一种用数字控制机床各部件运动的方法，通过直接向系统输入指令代码（数字和字母）来完成的。系统自动将这些指令代码转化成信号输出。这些信号依次控制机床各种部件的运动，比如主轴的启动和停止，刀具的转换，沿指定路径移动刀具和工件，控制切削液的通断等等。为了说明数控机床的重要性，我们来简单回顾一下传统机床的加工过程。操作者研究零件工作图后，调整合适的加工参数（如切削速度，进给量，切削深度，切削液等等），安排加工顺序，然后将工件夹紧在夹具（如卡盘或夹头）上，再开始加工。根据所规定的工件形状和尺寸精度，这种加工通常需要熟练的操作工。而且，其后续加工是由各个操作者完成的。由于存在不可避免的人为误差，即便由同一个人加工出来

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