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基于PLC控制的十字路口交通灯的设计【全套CAD图纸和毕业论文】【答辩优秀】

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摘  要


随着经济社会的发展，当今城市的基础设施处于严重超载状态，尤其交通问题越来越严重，解决交通问题已是城市管理者面对一大挑战，人、车、路三者关系协调程度决定着交通状况的重要因素。而交通灯是人，车，路三者联系的纽带，引入智能控制技术对交通灯进行控制很有必要，传统的交通信号灯控制一般采用电子线路和继电器实现，结构复杂，可靠性低，故障率高,较难实现功能的变更，本文利用可编程控制器PLC作为交通灯系统控制中心，PLC可编程序控制器是以微处理器为基础,综合了计算机技术、自动控制技术和通讯技术发展而来的一种新型工业控制装置。它具有结构简单、编程方便、可靠性高等优点,已广泛用于工业过程和位置的自动控制中。据统计,可编程控制器是工业自动化装置中应用最多的一种设备。专家认为,可编程控制器将成为今后工业控制的主要手段和重要的基础设备之一, PLC、机器人、CAD/CAM将成为工业生产的三大支柱。

由于PLC具有对使用环境适应性强的特性,同时其内部定时器资源十分丰富,可对目前普遍使用的“渐进式”信号灯进行精确控制,特别对多岔路口的控制可方便地实现。因此现在越来越多地将PLC应用于交通灯系统中控制功能强大，使用灵活方便，编程容易，功能扩展方便，结合交通的实际情况阐述了交通控制系统的工作原理，设计出了一种简单实用城市交通灯控制系统方案。与此同时，PLC 本身还具有通讯联网功能，将同一条道路上的信号灯组成一局域网进行统一调度管理，可缩短车辆通行等候时间，实现科学化管理。通过实验验证该系统具有较高的稳定性，较高的智能化，便于维护等优点。


关键词：PLC;交通灯;十字路口


Abstract


With the development of economic and social infrastructure of today's state of the city is seriously overloaded , especially the traffic problem is getting worse , to solve the traffic problem is a major challenge facing the city manager , people, vehicles , road decide the relations between the degree of coordination important factor in the transport position . The traffic light is the link people, vehicles , road three links , the introduction of intelligent control technology necessary to control traffic lights , traffic signal control is generally conventional electronic circuits and relays , complex structure, low reliability , the failure rate high , difficult to achieve change function , we use a programmable controller (PLC) as the traffic light system control center , PLC programmable logic controller is a microprocessor -based , integrated computer technology, automatic control technology and communication technology development to a new type of industrial control devices. It has a simple structure, easy programming, high reliability, has been widely used for automatic control of industrial processes and location. According to statistics, the programmable controller is a device for industrial automation applications up to a device . Experts believe that the programmable controller will become one of the primary means of future industrial control and critical infrastructure , PLC, robotics , CAD / CAM will be the three pillars of industrial production.

Due to the use of PLC has strong environmental adaptability characteristics , while its internal timer resources are very rich, the current widespread use of " progressive " signal for precise control , especially for multi- fork can be easily controlled . So now increasingly used in the PLC control system of traffic lights powerful, flexible and easy to use , easy to program , easy functionality expansion , combined with the actual situation of traffic elaborated works traffic control system , designed a simple practical urban traffic light control system solutions . Meanwhile , PLC communication itself also has networking capabilities , will form a road with lights on the unified management of a local area network , you can shorten the waiting time for vehicles to achieve scientific management. Experimental verification of the system has a high stability, high intelligence, ease of maintenance and other advantages .



Keywords: PLC; traffic lights; Crossroads


目    录


引言1

1  交通灯控制系统概述2

1.1 智能交通灯系统的发展背景2

1.1.1英国TRANSYT路面交通控制系统2

1.1.2澳大利亚SCAT路面控制系统2

1.1.3英国SCOOT路面控制系统2

1.1.4日本城市路面控制系统3

1.2 交通控制存在的问题3

1.3 本课题的主要研究内容4

2  PLC功能介绍4

2.1 PLC的基本概念和基本结构4

2.1.1 PLC的基本概念4

2.1.2 PLC的基本结构4

2.2 PLC的特点和应用领域6

2.2.1 PLC的特点6

2.2.2 PLC的应用领域7

2.3 PLC的工作原理7

2.3.1输入采样阶段8

2.3.2.用户程序执行阶段8

2.3.3.输出刷新阶段8

2.4 PLC的性能指标和软件系统9

2.4.1 PLC的性能指标9

2.4.2 PLC的软件系统9

2.5 PLC编程语言10

2.5.1梯形图10

2.5.2语句表10

2.6 PLC基本编程指令12

2.6.1输入输出指令（LD/LDI/OUT）12

2.6.3 电路块的并联和串联指令（ORB、ANB）13

2.6.4 程序结束指令（END）14

2.7 PLC控制系统设计概要14

2.7.1设计的基本原则和内容14

2.7.2设计的步骤和实现过程15

3  交通灯控制系统设计15

3.1 PLC型号的选定以及可行性分析15

3.1.1 FX2N-64MR 控制器主要性能指标16

3.2 设计思路16

3.3 模拟十字路口交通灯规则设计实物模型设计18

3.3.1控制要求18

4  控制系统程序设计24

4.1 PLC程序流程图设计24

4.2 PLC程序实现24

4.2.1 梯形图程序（状态步进形式的梯形图）26

4.2.2 指令表（梯形图对应的指令语句）40

5  总结47

5.1 设计总结47

5.2 检测和调试47

5.2.1硬件调试47

5.2.2软件调试48

谢  辞49

参考文献50

引言

据一项对美国主要城市交通状况的调查显示：1982年至2000年，美国城市在上下班高峰期间的交通堵塞状况不断加剧，由交通堵塞造成的时间和汽油浪费而带来的经济损失每年高达680亿美元。以广州为例来讲，现在市区平均车速只有每小时12公里。用这个目标速度代入欧美标准计算，广州人为交通堵塞所付出的经济代价总值：每年耗费1.5亿小时，减少生产总值117亿元。相当于该市整个生产总值的7%。

在北美、澳大利亚等大城市，道路面积率高达35%--40%，而北京只有20%。缓解交通拥堵，加快道路建设是当务之急。据悉，到2010年，北京将投资500亿元用于城市道路建设，到2005年，北京仅高速公路通车里程就达到600公里。但一味发展城市道路，也会刺激私家车超常规发展，两者发展速度的失衡，最终还是逃不出“拥堵—修路—再拥堵”的怪圈。

当今时代是一个自动化时代，交通灯控制等很多行业的设备都与计算机密切相关。因此，一个好的交通灯控制系统，将给道路拥挤、违章控制等方面给予技术革新。随着大规模集成电路及计算机技术的迅速发展，以及人工智能在控制技术方面的广泛运用，智能设备有了很大的发展，是现代科技发展的主流方向。本设计介绍了一个智能交通灯系统的设计。该智能交通灯控制系统可以实现的功能有：对某市区的四个主要交通路口进行监控；各路口有固定的工作周期，并且在道路拥挤时中控中心能改变其周期；对路口违章的机动车能够即时拍照，并提取车牌号。在世界范围内，一个以微电子技术，计算机和通信技术为先导的，以信息技术和信息产业为中心的信息革命方兴未艾。而计算机技术怎样与实际应用更有效的结合并有效的发挥其作用是科学界最热门的话题，也是当今计算机应用中空前活跃的领域。本文主要从单片机的应用上来实现十字路口交通灯智能化的管理，用以控制过往车辆的正常运作。

交通信号灯的出现，使交通得以有效管制，对于疏导交通流量、提高道路通行能力，减少交通事故有明显效果。为了实现交通道路的管理，力求交通管理先进性、科学化。用可编程控制器实现交通灯管制的控制系统，以及该系统软、硬件设计方法，实验证明该系统实现简单、经济，能够有效地疏导交通，提高交通路口的通行能力。分析了现代城市交通控制与管理问题的现状，结合交通的实际情况阐述了交通灯控制系统的工作原理，给出了一种简单实用的城市交通灯控制系统的PLC设计方案。可编程序控制器简称为PLC，它的应用面广、功能强大、使用方便，已经成为当代工业自动化的主要支柱之一。PLC已经广泛地应用在各种机械设备和生产过程的自动控制系统中，PLC在其他领域，例如在民用和家庭自动化设备中的应用也得到了迅速的发展。

随着微处理器、计算机和数字通信技术的飞速发展，计算机控制已经广泛的应用在所有的工业领域。现代社会要求制造业对市场需求做出迅速的反应，生产出小批量、多品种、多规格、低成本和高质量的产品。为了满足这一要求，生产设备和自动生产线的控制系统必须具有极高的可靠性和灵活性。可编程序控制器（Programmable Logic Controller）正是顺应这一要求出现的，它是以微处理器为基础的通用工业控制装置。

1  交通灯控制系统概述

1.1 智能交通灯系统的发展背景

1.1.1英国TRANSYT路面交通控制系统

英国道路研究所花费了十几年的时间，在大量的实验和经验的基础之上，研制出了TRANSYT路面交通控制系统。被全球400多个车市广泛采用，可以说TRANSYT系统的成功是显而易见的。TRANSYT内部通过有线来经行通信。采用静态模式来控制交通信号灯，这种控制方案中通过数学模型来控制绿信比和相位差。但是这种交通控制系统还是存在一定的缺陷，例如它无法优化周期，而且想要获得最优的整体分配方案是相当困难的。如果想要经行离线优化，必须采用大量的路网几何和交通数据流。

1.1.2澳大利亚SCAT路面控制系统

70年代末期，澳大利亚开发了SCAT路面控制系统 。SCAT采用分层递阶的计算机形式，这是一种较为先进的计算机网络控制技术。SCAT通过有线来通信。在地区联机，在中央即采用联机也采用脱机模式。在控制的过程中，SCAT会预先设定几个参数，在对路面情况经行分析的基础之上，根据实际的情况来选定具体采用那个数据。计算机结构好改变，控制方案好变换，而SCAT系统充分的利用了计算机的这些优点


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编号： 毕业设计(论文)任务书题 目：基于PLC控制的十字路口交通灯设计学院： 国防生学院 专 业：机械设计制造及其自动化学生姓名： 蔡秀滨 学 号： 1001020105 指导教师单位： 机电工程学院 姓 名： 郭中玲 职 称： 高级工程师 题目类型：理论研究 实验研究 工程设计 工程技术研究 软件开发 2013年12月9日一、 毕业设计（论文）的内容1；应用PLC的基本知识完成本课题的设计。2; 交通信号控制系统分析。 3; 交通灯控制系统设计二、 毕业设计（论文）的要求与数据1.完成十子路口交通灯基本规则的设计，掌握电器设计和电路设计的方法，撰写各个阶段的规范文档；2.掌握控制设计和结构设计的方法和步骤,具备较好的计算、分析和解决问题能力。3必需有“红” “绿” “黄”灯指示并且时间达配要恰当。三、毕业设计（论文）应完成的工作1、完成二万字左右的毕业设计说明书（论文）；在毕业设计说明书（论文）中必须包括详细的300-500个单词的英文摘要；2、独立完成与课题相关，不少于四万字符的指定英文资料翻译（附英文原文）；3、完成PLC接线图，制作实物模型，PLC梯形图。对于机电结合类课题，必须完成绘图工作量折合A0图纸1张以上，其中必须包含两张A3以上的计算机绘图图纸；四、应收集的资料及主要参考文献1 蒋大明 戴胜华. 自动控制原理M. 北京: 北京交通大学出版社. 2003.32 刘元扬主编. 自动检测和过程控制M. 北京: 冶金工业出版社. 2005.83 李晓辉 薛欣. 计算机辅助设计与绘图M. 北京: 清华大学出版社. 2006.64 汪恺主编. 机械设计标准应用手册M. 北京: 机械工业出版社. 1997.5 彭荣济. 机械设计手册M. 北京: 北京出版社. 1999.16 董杰主编. 机械设计工艺性手册M. 北京: 上海交道大学出版社. 1991.7 宋宝玉主编. 机械设计基础M. 哈尔滨: 哈尔滨工业大学出版社. 2006.8 邱公伟主编. 可编程控制器网络通信及应用M. 北京: 清华大学出版社. 2001.19 高兆安译. 自动化中的液压机构M. 北京: 机械工业出版社. 1999.10 Design of machine elements / zhai wenjie and Ao hongrui monograpn. 2007五、试验、测试、试制加工所需主要仪器设备及条件计算机(autoCAD,及pro/E,protel软件),任务下达时间：2013年12月9日毕业设计开始与完成时间：2013年12月17日至 2014年05 月8日组织实施单位：教研室主任意见：签字： 2013年12月14日院领导小组意见：签字： 2013 年12月16日2014年机电工程学院毕业设计(论文)进度计划表学生姓名： 学号：序号起止日期计划完成内容实际完成内容检查日期检查人签名12013.12.912.15教师填写，下同教师填写，下同22013.12.1612.2232013.12.2312.2942013.12.30-2014.1.552014.1.6-2014.1.1262014.1.13-2014.1.1972014.2.24-2014.3.282014.3.3-2014.3.9(本表同时作为指导教师对学生的16次考勤记录)2014年机电工程学院毕业设计进度计划表（续）学生姓名： 学号：序号起止日期计划完成内容实际完成内容检查日期检查人签名92014.3.10-2014.3.16教师填写，下同教师填写，下同102014.3.17-2014.3.23112014.3.24-2014.3.30122014.3.31-2014.4.6132014.4.7-2014.4.13142014.4.14-2014.4.20152014.4.21-2014.4.27162014.4.28-2014.5.4任务下达时间：2013年12月9日(本表同时作为指导教师对学生的16次考勤记录)编号： 毕业设计（论文）开题报告题 目： 基于PLC控制的十字路 口交通灯设计 院 （系）： 国防生学院 专 业：机械设计制造及其自动化学生姓名： 蔡秀滨 学 号： 1001020105 指导教师单位： 机电工程学院 姓 名： 郭中玲 职 称： 高级工程师 题目类型：理论研究 实验研究 工程设计 工程技术研究 软件开发2013年12月23日1本课题的研究内容、重点及难点随着社会的发展，人们的消费水平不断的提高，私人车辆不断的增加。人多、车多道路少的道路交通状况已经很明显了。所以采用有效的方法控制交通灯是势在必行的。PLC 的智能控制原则是控制系统的核心，采用PLC把东西方向或南北方向的车辆按数量规模进行分档，相应给定的东西方向与南北方向的绿灯时长也按一定的规律分档。 这样就可以实现按车流量规模给定绿灯时长，达到最大限度的有车放行，减少十字路口的车辆滞流，缓解交通拥挤、实现最优控制，从而提高了交通控制系统的效率.交通信号灯的出现，使交通得以有效管制，对于疏导交通流量、提高道路通行能力，减少交通事故有明显效果。为了实现交通道路的管理，力求交通管理先进性、科学化。用可编程控制器实现交通灯管制的控制系统，以及该系统软、硬件设计方法，实验证明该系统实现简单、经济，能够有效地疏导交通，提高交通路口的通行能力。分析了现代城市交通控制与管理问题的现状，结合交通的实际情况阐述了交通灯控制系统的工作原理，给出了一种简单实用的城市交通灯控制系统的PLC设计方案。其主要内容如下： 1、查阅资料。结合本次课题查阅相关资料； 2、撰写开题报告； 3、交通信号控制系统分析； 4、通过对产品的性能分析，完成相关的交通灯控制系统设计； 5、设计的系统结构要求完整、合理； 6、做出实物,检验设计是否合理； 7、撰写毕业设计（论文）说明书；毕业设计的重点：交通信号控制系统分析；交通灯控制系统设计；实物的制作；本课题的难点: 交通灯控制系统设计;实物的制作；掌握控制设计和结构设计的方法和步骤,具备较好的计算、分析和解决问题能力2准备情况（已查阅的参考文献或进行的调研）近年来随着科技的飞速发展，PLC的应用正在不断地走向深入，同时带动传统控制检测日新月益更新。它具有结构简单、编程方便、可靠性高等优点，已广泛用于工业过程和位置的自动控制中。据统计，可编程控制器是工业自动化装置中应用最多的一种设备。专家认为，可编程控制器将成为今后工业控制的主要手段和重要的基础设备之一，PLC、机器人、CAD/CAM将成为工业生产的三大支柱。由于PLC具有对使用环境适应性强的特性，同时其内部定时器资源十分丰富，可对目前普遍使用的“渐进式”信号灯进行精确控制，特别对多岔路口的控制可方便地实现。因此现在越来越多地将PLC应用于交通灯系统中。可编程序控制器在工业自动化中的地位极为重要，广泛的应用于各个行业。随着科技的发展，可编程控制器的功能日益完善，加上小型化、价格低、可靠性高，在现代工业中的作用更加突出。参考查阅的文献资料：1 蒋大明 戴胜华. 自动控制原理M. 北京: 北京交通大学出版社. 2003.32 刘元扬主编. 自动检测和过程控制M. 北京: 冶金工业出版社. 2005.83 李晓辉 薛欣. 计算机辅助设计与绘图M. 北京: 清华大学出版社. 2006.64 汪恺主编. 机械设计标准应用手册M. 北京: 机械工业出版社. 1997.75 彭荣济. 机械设计手册M. 北京: 北京出版社. 1999.16 董杰主编. 机械设计工艺性手册M. 北京: 上海交道大学出版社. 1991.67 宋宝玉主编. 机械设计基础M. 哈尔滨: 哈尔滨工业大学出版社. 2006.58 邱公伟主编. 可编程控制器网络通信及应用M. 北京: 清华大学出版社. 2001.19 高兆安译. 自动化中的液压机构M. 北京: 机械工业出版社. 1999.910 吴宗泽. 机械设计实用手册 M. 北京：机械工业出版社，2002.11 漆汉宏. PLC电气控制技术. M. 北京: 机械工业出版社,2012.512 高春甫. 三菱可编程序控制器应用技术.M.北京：机械工业出版社,2010.113 张华龙. 图解PLC与电气控制入门 M. 北京：北京人民邮电出版社，2008.914 Design of machine elements / zhai wenjie and Ao hongrui monograpn. 20073、实施方案、进度实施计划及预期提交的毕业设计资料1、2013年12月23日至2013年12月30日，理解消化毕设任务书要求并收集、分析、消化资料文献，根据毕设内容完成并交开题报告；2、2013年1月6日至2014年1月13日，开展调研，了解 PLC及交通灯的实际使用和原理，并完成部分英文摘要翻译。3、2014年3月4日至2013年3月31日，查阅资料，熟悉PLC的结构及有关计算，拟定方案设计及主要系统设计，拟定具体的PLC系统。4、2014年4月1日至2014年4月21日，完成设计计算任务，系统结构的设计和完成实物设计；5、2014年4月22日至2014年4月30日，完成设计，着手实物制作；6、2014年4月30日至2014年4月10日，完善设计制造出实物并完成论文的撰写；7、2014年4月20日至2014年4月26日，修改并打印毕业论文及整理相关资料，调试实物，交指导老师评阅，准备论文答辩。指导教师意见 指导教师（签字）： 2013年12月日开题小组意见 开题小组组长（签字）：2014年1 月日院（系、部）意见主管院长（系、部主任）签字： 2014年1月日2014年机电工程学院毕业设计(论文)进度计划表学生姓名： 学号：序号起止日期计划完成内容实际完成内容检查日期检查人签名12013.12.1712.23教师填写，下同教师填写，下同22013.12.2412.3032013.12.31-2014.1.642014.1.7-1.1353.4-3.1063.11-3.1773.18-3.2483.25-3.31(本表同时作为指导教师对学生的16次考勤记录)2014年机电工程学院毕业设计进度计划表（续）学生姓名： 学号：序号起止日期计划完成内容实际完成内容检查日期检查人签名94.01-4.07教师填写，下同教师填写，下同104.08-4.14114.15-4.21124.22-4.28134.29-5.05145.06-5.12155.13-5.19165.20-5.26完成毕业设计，提交论文任务下达时间：2013年12月17日(本表同时作为指导教师对学生的16次考勤记录)第 1 页 共 2 页毕业设计（论文）中期检查表（指导教师）指导教师姓名：郭中玲填表日期： 2014年 4 月 20 日学生学号1001020105学生姓名蔡秀滨题目名称基于PLC控制的十字路口交通灯设计已完成内容参观调研,查阅资料;完成PLC接线图;PLC梯形图;制作实物模型;完成英文翻译；撰写论文；完成毕业设计。 检查日期：2014-4-20完成情况全部完成按进度完成滞后进度安排存在困难组态控制较复杂，如不能完成将用硬件表达。解决办法查阅相关资料，并且与指导老师和同学们一起讨论解决方案。预期成绩优 秀良 好中 等及 格不及格建议 教师签名： 教务处实践教学科制表说明：1、本表由检查毕业设计的指导教师如实填写；2、此表要放入毕业设计（论文）档案袋中；3、各院(系)分类汇总后报教务处实践教学科备案 编号： 毕业设计(论文)外文翻译（原文）院 （系）： 国防生学院 专 业：机械设计制造及其自动化 学生姓名： 蔡秀滨 学 号： 1001020105 指导教师单位： 机电工程学院 姓 名： 郭中玲 职 称： 高级工程师 2014年 3 月 9 日Contents1.The Injection Molding12.Automated surface nishing of plastic injection mold steel with spherical grinding and ball burnishing processes14第 22 页 共 23 页 桂林电子科技大学毕业（论文）报告专用纸 The Injection Molding Alp Tekin Ergenc , Deniz Ozde KocaYildiz Tecnical University, Mechanical Engineering Department, IC Engines Laboratory, TurkeyThe Introduction of MoldsThe mold is at the core of a plastic manufacturing process because its cavity gives a part its shape. This makes the mold at least as critical-and many cases more so-for the quality of the end product as, for example, the plasticiting unit or other components of the processing equipment.Mold MaterialDepending on the processing parameters for the various processing methods as well as the length of the production run, the number of finished products to be produced, molds for plastics processing must satisfy a great variety of requirements. It is therefore not surprising that molds can be made from a very broad spectrum of materials, including-from a technical standpoint-such exotic materials as paper matched and plaster. However, because most processes require high pressures, often combined with high temperatures, metals still represent by far the most important material group, with steel being the predominant metal. It is interesting in this regard that, in many cases, the selection of the mold material is not only a question of material properties and an optimum price-to-performance ratio but also that the methods used to produce the mold, and thus the entire design, can be influenced.A typical example can be seen in the choice between cast metal molds, with their very different cooling systems, compared to machined molds. In addition, the production technique can also have an effect; for instance, it is often reported that, for the sake of simplicity, a prototype mold is frequently machined from solid stock with the aid of the latest technology such as computer-aided (CAD) and computer-integrated manufacturing (CIMS). In contrast to the previously used methods based on the use of patterns, the use of CAD and CAM often represents the more economical solution today, not only because this production capability is available pin-house but also because with any other technique an order would have to be placed with an outside supplier.Overall, although high-grade materials are often used, as a rule standard materials are used in mold making. New, state-of-the art (high-performance) materials, such as ceramics, for instance, are almost completely absent. This may be related to the fact that their desirable characteristics, such as constant properties up to very high temperatures, are not required on molds, whereas their negative characteristics, e. g. low tensile strength and poor thermal conductivity, have a clearly related to ceramics, such as sintered material, is found in mild making only to a limited degree. This refers less to the modern materials and components produced by powder metallurgy, and possibly by hot isocratic pressing, than to sintered metals in the sense of porous, air-permeable materials.Removal of air from the cavity of a mold is necessary with many different processing methods, and it has been proposed many times that this can be accomplished using porous metallic materials. The advantages over specially fabricated venting devices, particularly in areas where melt flow fronts meet, I, e, at weld lines, are as obvious as the potential problem areas: on one hand, preventing the texture of such surfaces from becoming visible on the finished product, and on the other hand, preventing the microspores from quickly becoming clogged with residues (broken off flash, deposits from the molding material, so-called plate out, etc.). It is also interesting in this case that completely new possibilities with regard to mold design and processing technique result from the use of such materials. A. Design rules There are many rules for designing molds. These rules and standard practices are based on logic, past experience, convenience, and economy. For designing, mold making, and molding, it is usually of advantage to follow the rules. But occasionally, it may work out better if a rule is ignored and an alternative way is selected. In this text, the most common rules are noted, but the designer will learn only from experience which way to go. The designer must ever be open to new ideas and methods, to new molding and mold materials that may affect these rules.B. The basic mold1. Mold cavity space The mold cavity space is a shape inside the mold, “excavated” in such a manner that when the molding material is forced into this space it will take on the shape of the cavity space and, therefore, the desired product. The principle of a mold is almost as old as human civilization. Molds have metals into sand forms. Such molds, which are still used today in foundries, can be used only once because the mold is destroyed to release the product after it has solidified. Today, we are looking for permanent molds that can be used over and over. Now molds are made from strong, durable materials, such as steel, or from softer aluminum or metal alloys and even from certain plastics where a long mold life is not required because the planned production is small. In injection molding the plastic is injected into the cavity space with high pressure, so the mold must be strong enough to resist the injection pressure without deforming.2. Number of cavities Many molds, particularly molds for larger products, are built for only cavity space, but many molds, especially large production molds, are built with 2 or more cavities. The reason for this is purely economical. It takes only little more time to inject several cavities than to inject one. For example, a 4-cavity mold requires only one-fourth of the machine time of a single-cavity mold. Conversely, the production increases in proportion to the number of cavities. A mold with more cavities is more expensive to build than a single-cavity mold, but not necessarily 4 times as much as a single-cavity mold. But it may also require a larger machine with larger platen area and more clamping capacity, and because it will use 4 times the amount of plastic, it may need a large injection unit, so the machine hour cost will be higher than for a machine large enough for the smaller mold.3. Cavity shape and shrinkage The shape of the cavity is essentially the “negative” of the shape of the desired product, with dimensional allowance added to allow for shrinking of the plastic. The shape of the cavity is usually created with chip-removing machine tools, or with electric discharge machining, with chemical etching, or by any new method that may be available to remove metal or build it up, such as galvanic processes. It may also be created by casting certain metals in plaster molds created from models of the product to be made, or by casting some suitable hard plastics. The cavity shape can be either cut directly into the mold plates or formed by putting inserts into the plates.C. Cavity and core By convention, the hollow portion of the cavity space is called the cavity. The matching, often raised portion of the cavity space is called the core. Most plastic products are cup-shaped. This does not mean that they look like a cup, but they do have an inside and an outside. The outside of the product is formed by the cavity, the inside by the core. The alternative to the cup shape is the flat shape. In this case, there is no specific convex portion, and sometimes, the core looks like a mirror image of the cavity. Typical examples for this are plastic knives, game chips, or round disks such as records. While these items are simple in appearance, they often present serious molding problems for ejection of the product. The reason for this is that all injection molding machines provide an ejection mechanism on the moving platen and the products tend to shrink onto and cling to the core, from where they are then ejected. Most injection molding machines do not provide ejection mechanisms on the injection side.Polymer Processing Polymer processing, in its most general context, involves the transformation of a solid (sometimes liquid) polymeric resin, which is in a random form (e.g., powder, pellets, beads), to a solid plastics product of specified shape, dimensions, and properties. This is achieved by means of a transformation process: extrusion, molding, calendaring, coating, thermoforming, etc. The process, in order to achieve the above objective, usually involves the following operations: solid transport, compression, heating, melting, mixing, shaping, cooling, solidification, and finishing. Obviously, these operations do not necessarily occur in sequence, and many of them take place simultaneously. Shaping is required in order to impart to the material the desired geometry and dimensions. It involves combinations of viscoelastic deformations and heat transfer, which are generally associated with solidification of the product from the melt. Shaping includes: two-dimensional operations, e.g. die forming, calendaring and coating; three-dimensional molding and forming operations. Two-dimensional processes are either of the continuous, steady state type (e.g. film and sheet extrusion, wire coating, paper and sheet coating, calendaring, fiber spinning, pipe and profile extrusion, etc.) or intermittent as in the case of extrusions associated with intermittent extrusion blow molding. Generally, molding operations are intermittent, and, thus, they tend to involve unsteady state conditions. Thermoforming, vacuum forming, and similar processes may be considered as secondary shaping operations, since they usually involve the reshaping of an already shaped form. In some cases, like blow molding, the process involves primary shaping (pair-son formation) and secondary shaping (pair son inflation). Shaping operations involve simultaneous or staggered fluid flow and heat transfer. In two-dimensional processes, solidification usually follows the shaping process, whereas solidification and shaping tend to take place simultaneously inside the mold in three dimensional processes. Flow regimes, depending on the nature of the material, the equipment, and the processing conditions, usually involve combinations of shear, extensional, and squeezing flows in conjunction with enclosed (contained) or free surface flows. The thermo-mechanical history experienced by the polymer during flow and solidification results in the development of microstructure (morphology, crystallinity, and orientation distributions) in the manufactured article. The ultimate properties of the article are closely related to the microstructure. Therefore, the control of the process and product quality must be based on an understanding of the interactions between resin properties, equipment design, operating conditions, thermo-mechanical history, microstructure, and ultimate product properties. Mathematical modeling and computer simulation have been employed to obtain an understanding of these interactions. Such an approach has gained more importance in view of the expanding utilization of computer design/computer assisted manufacturing/computer aided engineering (CAD/CAM/CAE) systems in conjunction with plastics processing. It will emphasize recent developments relating to the analysis and simulation of some important commercial process, with due consideration to elucidation of both thermo-mechanical history and microstructure development. As mentioned above, shaping operations involve combinations of fluid flow and heat transfer, with phase change, of a visco-elastic polymer melt. Both steady and unsteady state processes are encountered. A scientific analysis of operations of this type requires solving the relevant equations of continuity, motion, and energy (I. e. conservation equations).Injection Molding Many different processes are used to transform plastic granules, powders, and liquids into final product. The plastic material is in moldable form, and is adaptable to various forming methods. In most cases thermoplastic materials are suitable for certain processes while thermosetting materials require other methods of forming. This is recognized by the fact that thermoplastics are usually heated to a soft state and then reshaped before cooling. Theromosets, on the other hand have not yet been polymerized before processing, and the chemical reaction takes place during the process, usually through heat, a catalyst, or pressure. It is important to remember this concept while studying the plastics manufacturing processes and the polymers used. Injection molding is by far the most widely used process of forming thermoplastic materials. It is also one of the oldest. Currently injection molding accounts for 30% of all plastics resin consumption. Since raw material can be converted by a single procedure, injection molding is suitable for mass production of plastics articles and automated one-step production of complex geometries. In most cases, finishing is not necessary. Typical products include toys, automotive parts, household articles, and consumer electronics goods, Since injection molding has a number of interdependent variables, it is a process of considerable complexity. The success of the injection molding operation is dependent not only in the proper setup of the machine variables, but also on eliminating shot-to-shot variations that are caused by the machine hydraulics, barrel temperature variations, and changes in material viscosity. Increasing shot-to-shot repeatability of machine variables helps produce parts with tighter tolerance, lowers the level of rejects, and increases product quality ( i.e., appearance and serviceability). The principal objective of any molding operation is the manufacture of products: to a specific quality level, in the shortest time, and using a repeatable and fully automatic cycle. Molders strive to reduce or eliminate rejected parts, or parts with a high added value such as appliance cases, the payoff of reduced rejects is high. A typical injection molding cycle or sequence consists of five phases:1 Injection or mold filling2 Packing or compression3 Holding4 Cooling5 Part ejectionInjection Molding OverviewProcessInjection molding is a cyclic process of forming plastic into a desired shape by forcingthe material under pressure into a cavity. The shaping is achieved by cooling(thermoplastics) or by a chemical reaction (thermosets). It is one of the most commonand versatile operations for mass production of complex plastics parts with excellentdimensional tolerance. It requires minimal or no finishing or assembly operations. Inaddition to thermoplastics and thermosets, the process is being extended to suchmaterials as fibers, ceramics, and powdered metals, with polymers as binders.ApplicationsApproximately 32 percent by weight of all plastics processed go through injection moldingmachines. Historically, the major milestones of injection molding include the invention of thereciprocating screw machine and various new alternative processes, and the application of computersimulation to the design and manufacture of plastics parts.Development of the injection molding machineSince its introduction in the early 1870s, the injection molding machine has undergone significantmodifications and improvements. In particular, the invention of the reciprocating screw machine hasrevolutionized the versatility and productivity of the thermoplastic injection molding process.Benefits of the reciprocating screwApart from obvious improvements in machine control and machine functions, the majordevelopment for the injection molding machine is the change from a plunger mechanism to areciprocating screw. Although the plunger-type machine is inherently simple, its popularity waslimited due to the slow heating rate through pure conduction only. The reciprocating screw canplasticize the material more quickly and uniformly with its rotating motion, as shown in Figure 1. Inaddition, it is able to inject the molten polymer in a forward direction, as a plunger.Development of the injection molding processThe injection molding process was first used only with thermoplastic polymers. Advances in theunderstanding of materials, improvements in molding equipment, and the needs of specific industrysegments have expanded the use of the process to areas beyond its original scope.Alternative injection molding processesDuring the past two decades, numerous attempts have been made to develop injection moldingprocesses to produce parts with special design features and properties. Alternative processes derivedfrom conventional injection molding have created a new era for additional applications, more designfreedom, and special structural features. These efforts have resulted in a number of processes,including: Co-injection (sandwich) molding Fusible core injection molding) Gas-assisted injection molding Injection-compression molding Lamellar (microlayer) injection moldin Live-feed injection molding Low-pressure injection molding Push-pull injection molding Reactive molding Structural foam injection molding Thin-wall moldingComputer simulation of injection molding processesBecause of these extensions and their promising future, computer simulation of the process has alsoexpanded beyond the early lay-flat, empirical cavity-filling estimates. Now, complex programs simulate post-filling behavior, reaction kinetics, and the use of two materials with different properties, or two distinct phases, during the process.The Simulation section provides information on using C-MOLD products.Among the Design topicsare several examples that illustrate how you can use CAE tools to improve your part and molddesign and optimize processing conditions.Co-injection (sandwich) moldingOverviewCo-injection molding involves sequential or concurrent injection of two different butcompatible polymer melts into a cavity. The materials laminate and solidify. This processproduces parts that have a laminated structure, with the core material embedded betweenthe layers of the skin material. This innovative process offers the inherent flexibility ofusing the optimal properties of each material or modifying the properties of the moldedpart.FIGURE 1. Four stages of co-injection molding. (a) Short shot of skin polymer melt (shown in dark green)is injected into the mold. (b) Injection of core polymer melt until cavity is nearly filled, as shown in (c). (d)Skin polymer is injected again, to purge the core polymer away from the sprue.Fusible core injection moldingOverviewThe fusible (lost, soluble) core injection molding process illustrated below producessingle-piece, hollow parts with complex internal geometry. This process molds a coreinside the plastic part. After the molding, the core will be physically melted or chemicallydissolved, leaving its outer geometry as the internal shape of the plastic part.FIGURE 1. Fusible (lost, soluble) core injection moldingGas-assisted injection moldingGas-assisted processThe gas-assisted injection molding process begins with a partial or full injection ofpolymer melt into the mold cavity. Compressed gas is then injected into the core of thepolymer melt to help fill and pack the mold. This process is illustrated below.FIGURE 1. Gas-assisted injection molding: (a) the electrical system, (b) the hydraulic system, (c) the control panel, and (d) the gas cylinder.Injection-compression moldingOverviewThe injection-compression molding process is an extension of conventional injectionmolding. After a pre-set amount of polymer melt is fed into an open cavity, it iscompressed, as shown below. The compression can also take place when the polymer isto be injected. The primary advantage of this process is the ability to producedimensionally stable, relatively stress-free parts, at a low clamp tonnage (typically 20 to50 percent lower).Lamellar (microlayer) injection moldingOverviewThis process uses a feedblock and layer multipliers to combine melt streams from dualinjection cylinders. It produces parts from multiple resins in distinct microlayers, asshown in Figure 1 below. Combining different resins in a layered structure enhances anumber of properties, such as the gas barrier property, dimensional stability, heatresistance, and optical clarity.Live-feed injection moldingOverviewThe live-feed injection molding process applies oscillating pressure at multiple polymerentrances to cause the melt to oscillate, as shown in the illustration below. The action ofthe pistons keeps the material in the gates molten while different layers of molecular orfiber orientation are being built up in the mold due to solidification. This process providesa means of making simple or complex parts that are free from voids, cracks, sink marks,and weld-line defects.Low-pressure injection moldingOverviewLow-pressure injection molding is essentially an optimized extension of conventionalinjection molding (see Figure 1). Low pressure can be achieved by properly programmingthe screw revolutions per minute, hydraulic back pressure, and screw speed to controlthe melt temperature and the injection speed. It also makes use of a generous gate size ora n reduce umber of valve gates that open and close sequentially to reduce the flow length. Thepacking stage is eliminated with a generally slow and controlled injection speed. Thebenefits of low-pressure injection molding include a reduction of the clamp force tonnagerequirement, less costly molds and presses, and lower stress in the molded parts.Push-pull injection moldingOverviewThe push-pull injection molding process uses a conventional twin-component injectionsystem and a two-gate mold to force material to flow back and forth between a masterinjection unit and a secondary injection unit, as shown below. This process eliminatesweld lines, voids, and cracks, and controls the fiber orientation.Reactive molding ProcessingMajor reactive molding processes include reactive injection molding (RIM), and compositesprocessing, such as resin transfer molding (RTM) and structural reactive injection molding (SRIM).The typically low viscosity of the reactive materials permits large and complex parts to be moldedwith relatively lower pressure and clamp tonnage than required for thermoplastics molding.relatively For example, to make high-strength and low-volume large parts, RTM and SRIM can be used to include a preform made of long fibers. Another area that is receiving more attention than ever before is the encapsulation of microelectronic IC chips.The adaptation of injection molding to these materials includes only a small increase in temperature in the feed mechanism (barrel) to avoid pre-curing. The cavity, however, is usually hot enough to initiate chemical cross-linking. As the warm pre-polymer is forced into the cavity, heat is added from the cavity wall, from viscous (frictional) heating of the flow, and from the heat released by the reacting components. The temperature of the part often exceeds the temperature of the mold. When the reaction is sufficiently advanced for the part to be rigid (even at a high temperature) the cycle is complete and the part is ejected.Design considerationsThe mold and process design for injection molding of reactive materials is much more complexbecause of the chemical reaction that takes place during the filling and post-filling stages. Forinstance, slow filling often causes premature gelling and a resultant short shot, while fast fillingcould induce turbulent flow that creates internal porosity. Improper control of mold-walltemperature and/or inadequate part thickness will either give rise to moldability problems duringinjection, or cause scorching of the materials. Computer simulation is generally recognized as amore cost-effective tool than the conventional, time-consuming trial-and-error method for tool andprocess debugging.Structural foam injection moldingOverviewStructural foam molding produces parts consisting of solid external skin surfacessurrounding an inner cellular (or foam) core, as illustrated in Figure 1 below. This processis suitable for large, thick parts that are subject to bending loads in their end-use application. Structural foam parts can be produced with both low and high pressure, withnitrogen gas or chemical blowing agents.Thin-wall moldingOverviewThe term thin-wall is relative. Conventional plastic parts are typically 2 to 4 mm thick.Thin-wall designs are called advanced when thicknesses range from 1.2 to 2 mm, andleading-edge when the dimension is below 1.2 mm. Another definition of thin-wallmolding is based on the flow-length-to-wall-thickness ratios. Typical ratios for thesethin-wall applications range from 100:1 to 150:1 or more.Typical applicationsThin-wall molding is more popular in portable communication and computing equipment, whichdemand plastic shells that are much thinner yet still provide the same mechanical strength asconventional parts.ProcessingBecause thin-wall parts freeze off quickly, they require high melt temperatures, high injectiospeeds, and very high injection pressures if multiple gates or sequential valve gating are not an optimized ram-speed profile helps to reduce the pressure requirement.Due to the high velocity and shear rate in thin-wall molding, orientation occurs more readilyhelp minimize anisotropic shrinkage in thin-wall parts, it is important to pack the part adequately while the core is still molten.Injection molding machineComponentsFor thermoplastics, the injection molding machine converts granular or pelleted rawplastic into final molded parts via a melt, inject, pack, and cool cycle. A typical injectionmolding machine consists of the following major components, as illustrated in Figure 1below.Machine functionInjection molding machines can be generally classified into three categories, based on machinefunction:General-purpose machinesPrecision, tight-tolerance machinesHigh-speed, thin-wall machinesAuxiliary equipmentThe major equipment auxiliary to an injection molding machine includes resin dryers,materials-handling equipment, granulators, mold-temperature controllers and chillers, part-removal robots, and part-handling equipment.Automated surface nishing of plastic injection mold steel with spherical grinding and ball burnishing processesC. Apreaa, R. Mastrullob, C. Rennoa,*Department of Mechanical Engineering, University of Salerno, Via Ponte Don Melillo 1, 84084 Fisciano (Salerno), ItalybDETEC, University of Naples Federico II, P.le Tecchio 80, 80125 Naples, ItalyReceived 8 August 2002; received in revised form 18 December 2003; accepted 18 February 2004AbstractThis study investigates the possibilities of automated spherical grinding and ball burnishing surface nishing processes in a freeform surface plastic injection mold steel PDS5 on a CNC machining center. The design and manufacture of a grinding tool holder has been accomplished in this study.The optimal surface grinding parameters were determined usingTaguchis orthogonal array method for plastic injection moldingsteel PDS5 on a machining center. The optimal surface grinding parameters for the plastic injection mold steel PDS5 werethe combination of an abrasive material of PA Al2O3, a grinding speed of 18 000 rpm, a grinding depth of 20 m, and a feed of 50 mm/min. The surface roughness Raof the specimen can be improved from about 1.60 m to 0.35 m by using the optimal parameters for surface grinding. Surface roughness Ra can befurther improved from about 0.343 m to 0.06 m by using the ball burnishing process with the optimal burnishing parameters.Applying the optimal surface grinding and burnishing parame-ters sequentially to a ne-milled freeform surface mold insert,the surface roughness Raof freeform surface region on the tested part can be improved from about 2.15 m to 0.07 m.Keywords:Automated surface nishing；Ball burnishing process；Grinding process；Surface roughness；Taguchis method1 IntroductionPlastics are important engineering materials due to their specic characteristics, such as corrosion resistance, resistance to chemicals, low density, and ease of manufacture, and have increasingly replaced metallic components in industrial applications. Injection molding is one of the important forming processes for plastic products. The surface nish quality of the plastic injection mold is an essential requirement due to its direct effects on the appearance of the plastic product. Finishing processes such as grinding, polishing and lapping are commonly used to improve the surface nish. The mounted grinding tools (wheels) have been widely used in conventional mold and die nishing industries. The geometric model of mounted grinding tools for automated surface nishing processes was introduced in 1. A nishing process model of spherical grinding tools for automated surface nishing systems was developed in 2. Grinding speed, depth of cut, feed rate, and wheel properties such as abrasive material and abrasive grain size, are the dominant parameters for the spherical grinding process, as shown in Fig. 1. The optimal spherical grinding parameters for the injection mold steel have not yet been investigated based in the literature.In recent years, some research has been carried out in determining the optimal parameters of the ball burnishing process (Fig. 2). For instance, it has been found that plastic deformation on the workpiece surface can be reduced by using a tungsten carbide ball or a roller, thus improving the surface roughness, surface hardness, and fatigue resistance 36. The burnishing process is accomplished by machining centers 3, 4 and lathes 5, 6. The main burnishing parameters having signicant effects on the surface roughness are ball or roller material,burnishing force, feed rate, burnishing speed, lubrication, and number of burnishing passes, among others 3. The optimal surface burnishing parameters for the plastic injection mold steel PDS5 were a combination of grease lubricant, the tungsten carbide ball, a burnishing speed of 200 mm/min, a burnishing force of 300 N, and a feed of 40 m 7. The depth of penetration of the burnished surface using the optimal ball burnishing parameters was about 2.5 microns. The improvement of the surface roughness through burnishing process generally ranged between 40% and 90% 37.The aim of this study was to develop spherical grinding and ball burnishing surface nish processes of a freeform surface plastic injection mold on a machining center. The owchart of automated surface nish using spherical grinding and ball burnishing processes is shown in Fig. 3. We began by designing and manufacturing the spherical grinding tool and its alignment device for use on a machining center. The optimal surface spherical grinding parameters were determined by utilizing a Taguchis orthogonal array method. Four factors and three corresponding levels were then chosen for the Taguchis L18matrix experiment.The optimal mounted spherical grinding parameters for surface grinding were then applied to the surface nish of a freeform surface carrier. To improve the surface roughness, the ground surface was further burnished, using the optimal ball burnishing parameters.Fig. 1. Schematic diagram of the spherical grinding process Fig. 2. Schematic diagram of the ball-burnishing processFig. 3. Flowchart of automated surface nish using spherical grinding and ball burnishing processes2 Design of the spherical grinding tool and its alignment deviceTo carry out the possible spherical grinding process of a freeform surface, the center of the ball grinder should coincide with the z-axis of the machining center. The mounted spherical grinding tool and its adjustment device was designed, as shown in Fig. 4. The electric grinder was mounted in a tool holder with two adjustable pivot screws. The center of the grinder ball was well aligned with the help of the conic groove of the alignment components. Having aligned the grinder ball, two adjustable pivot screws were tightened; after which, the alignment components could be removed. The deviation between the center coordinates of the ball grinder and that of the shank was about 5 m, which was measured by a CNC coordinate measuring machine. The force induced by the vibration of the machine bed is absorbed by a helical spring. The manufactured spherical grinding tool and ball-burnishing tool were mounted, as shown in Fig. 5. The spindle was locked for both the spherical grinding process and the ball burnishing process by a spindle-locking mechanism.3 Planning of the matrix experiment3.1 Conguration of Taguchis orthogonal arrayThe effects of several parameters can be determined efciently by conducting matrix experiments using Taguchis orthogonal array 8. To match the aforementioned spherical grinding parameters, the abrasive material of the grinder ball (with the diameter of 10 mm), the feed rate, the depth of grinding, and the revolution of the electric grinder were selected as the four experimental factors (parameters) and designated as factor A to D (see Table 1) in this research. Three levels (settings) for each factor were congured to cover the range of interest, and were identied by the digits 1, 2, and 3. Three types of abrasive materials, namely silicon carbide (SiC), white aluminum oxide (Al2O3, WA), and pink aluminum oxide (Al2O3, PA), were selected and studied. Three numerical values of each factor were determined based on the pre-study results. The L18 orthogonal array was selected to conduct the matrix experiment for four 3-level factors of the spherical grinding process.Fig. 4. Schematic illustration of the spherical grinding tool and its adjustment deviceFig. 5. a Photo of the spherical grinding tool b Photo of the ball burnishing tool3.2 Denition of the data analysisEngineering design problems can be divided into smaller-the-better types, nominal-the-best types, larger-the-better types, signed-target types, among others 8. The signal-to-noise (S/N) ratio is used as the objective function for optimizing a product or process design. The surface roughness value of the ground surface via an adequate combination of grinding parameters should be smaller than that of the original surface. Consequently, the spherical grinding process is an example of a smaller-the-better type problem. The S/N ratio, is dened by the following equation 8: =10 log （mean square quality characteristic)=10 logwhere:yi: observations of the quality characteristic under different noise conditionsn: number of experimentAfter the S/N ratio from the experimental data of each L18 orthogonal array is calculated, the main effect of each factor was determined by using an analysis of variance (ANOVA) technique and an F-ratio test 8. The optimization strategy of the smaller-the better problem is to maximize , as dened by Eq. 1. Levels that maximize will be selected for the factors that have a signicant effect on. The optimal conditions for spherical grinding can then be determined.Table 1. The experimental factors and their levels4 Experimental work and resultsThe material used in this study was PDS5 tool steel (equivalent to AISI P20) 9, which is commonly used for the molds of large plastic injection products in the eld of automobile components and domestic appliances. The hardness of this material is about HRC33 (HS46) 9. One specic advantage of this material is that after machining, the mold can be directly used for further nishing processes without heat treatment due to its special pre-treatment. The specimens were designed and manufactured so that they could be mounted on a dynamometer to measure the reaction force. The PDS5 specimen was roughly machined and then mounted on the dynamometer to carry out the ne milling on a three-axis machining center made by YangIron Company (type MV-3A), equipped with a FUNUC Company NC-controller (type 0M) 10. The pre-machined surface roughness was measured, using Hommelwerke T4000 equipment, to be about 1.6 m. Figure 6 shows the experimental set-up of the spherical grinding process. A MP10 touch-trigger probe made by the Renishaw Company was also integrated with the machining center tool magazine to measure and determine the coordinated origin of the specimen to be ground. The NCcodes needed for the ball-burnishing path were generated by PowerMILL CAM software. These codes can be transmitted to the CNC controller of the machining center via RS232 serial interface.Table 2 summarizes the measured ground surface roughness value Raand the calculated S/N ratio of each L18orthogonal array using Eq. 1, after having executed the 18 matrix experiments. The average S/N ratio for each level of the four factors can be obtained, as listed in Table 3, by taking the numerical values provided in Table 2. The average S/N ratio for each level of the four factors is shown graphically in Fig. 7.Table 2. Ground surface roughness of PDS5 specimenFig. 6. Experimental set-up to determine the optimal spherical grinding parametersTable 3. Average S/N ratios by factor levels (dB)Fig. 7. Plots of control factor effectsThe goal in the spherical grinding process is to minimize the sur
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