充电器外壳注射模具设计【一模二腔】【侧抽芯】【说明书+CAD+PROE】
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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1000110532学生姓名郑波题目名称充电器外壳注射模具设计已完成内容开题并做调研,进行翻译;确定其方案设计;完成结构设计;绘制结构草图;完成相关计算;完成英文翻译;绘制装配图;绘制零件图;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)任务书题 目:充电器外壳注射模具设计学院: 国防生学院 专 业:机械设计制造及其自动化学生姓名: 郑波 学 号: 1000110532 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.塑件的分析.2.塑件材料的选用与性能分析. 3.拟定模具的结构形式. 4.浇注系统的设计. 5.分流道的设计. 6.浇口的设计. 7.冷料穴和拉料杆的设计. 8.成型零件的设计. 9.脱模推出机构的设计. 10.侧向分型与抽芯机构设计.11排气系统的设计. 12. 温度调节系统的设计.二、毕业设计(论文)的要求与数据要求:1.外型尺寸及配合精度必需标注. 2.使用环境为-1040. 3.电气性能符合GB标准.4.外观要求美观牢固. 5.根据实际情况确定脱模斜度. 6.ABS主要技术指标及工艺参数. 7.设计中的计算. 8.安装尺寸的校核. 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、用AutoCAD软件绘制系统设计图纸,模具的装配图,零件图和塑件图打印图纸折合0号图纸1张以上。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 李学峰.塑料模设计及制造.M.北京:机械工业出版社,20012 翁其金.塑料模塑成型技术. M.北京:机械工业出版社,2002.3 冯炳尧等.模具设计与制造简明手册(第二版)M.上海科学技术出版社,2008.4 钱泉森.塑料成型工艺及模具设计. M.济南:山东科学技术出版社,20045 塑料模设计手册编著组.塑料设计手册.北京:机械工业出版社,20026 陈剑鹤.模具设计基础. M.北京:机械工业出版社,20047 王文广等.塑料注塑模具设计技巧与实例.M.北京:化学工业出版社,20048 章飞.型腔模具设计与制造. M.北京:化学工业出版社,20039 田宝善等.塑料注射模设计实例及技巧. M.北京:化学工业出版社,200910 朱光.塑料注塑模中小型模架及其技术条件.M.北京:清华大学出版社,200311 宋满仓等.注塑模具设计. M.北京:电子工业出版社,201012 许鹤峰.注塑模设计要点与图例. M.北京:化学工业出版社,200313 cunha,L,et.al.,performance of chromium nitride and titanium nitride coatings during platics injection moulding. Surface and coating Technology,2002.153(2-3):p.160-165.五、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9日至 2014年05 月4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: 充电器外壳注射模具设计院 (系): 国防生学院 专 业: 机械设计制造及其自动化 学生姓名: 郑波 学 号: 1000110532 指导教师单位: 机电工程学院 姓 名: 郭中玲 职 称: 讲 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毕业设计的主要内容、重点和难点等毕业设计的主要内容:毕业设计课题为时尚艺术塑料板凳注塑模具设计。近几年,我国塑料模具工业有了很大的发展,塑料制品在我们的日常生活中扮演着越来越重要的角色,其种类也越来越多,制造加工也越来越精致美观。在未来的模具市场中,塑料模具发展的速度将高于其它模具,在模具行业中的比例将逐步提高。并且随着注塑模具技术的发展,在工程机械和工业机械、电子、汽车、家电、玩具等产品中,60%以上的零部件,可以依靠模具成型。随着国内经济发展,居民生活水平的提高,塑料板凳已经成为日常生活中常备的用品。塑料板凳也出现了多种样式,其中更多的板凳以其精美的外观,低廉的价格,以及耐用的特点而受到企业和广大消费者的欢迎。塑料板凳虽然看似简单,但是其注塑模具的设计制造所涉及的知识面和知识点比较多,能比较全面的反应一些注塑模具设计的特点。本课题应用性强,知识面覆盖较广,并且来自生活,所以容易激发我学习研究的兴趣,所以选择了这个课题,其主要内容如下:1、参观调研,查阅资料。到模具制造相关企业调研,了解模具设计、生产、制造及加工情况。结合本次毕设课题,查阅模具相关资料;2、 撰写开题报告;3、通过对产品的性能分析,完成相关的模具结构与零件设计;4、设计的模具结构要求完整、合理;5、合理选择尺寸、公差、表面粗糙度和制件材料,绘制的产品图样完整;6、认真分析制件图,确定模具型腔、模具结构、分型面和进料口形式,计算含收缩率的相关尺寸和模具的强度和刚度;7、 翻译专业外语文献。8、 撰写毕业设计(论文)说明书;9、 绘制模具总装图、零件图;毕业设计的重点难点:1、脱模推出机构和侧抽芯机构的设计;2、塑件的合理性设计及结构工艺性分析;3、材料选择及相关参数的计算;4、模具型腔数的确定,模具结构、分型面和进料口形式的选择;5、保证塑件成型时无变形,注出的制件表面光滑,无气泡和其它缺陷,无飞边或少飞边。6、绘制模具总装图、零件图及尺寸标注。2准备情况(查阅过的文献资料及调研情况、现有设备、实验条件等)1、模具技术的现状模具是汽车、电子、电器、航空、仪表、轻工、塑料、日用品等工业部门极其重要的工艺装备。没有模具、就没有高质量的产品。模具不是一般的工艺装备,而是技术密集型的产品,工业发达国家把模具作为机械制造方面的高科技产品来对待。他们认为:“模具是发展工业的一把钥匙;模具是一个企业的心脏;模具是富裕社会的一种动力”。近年来,我国塑料模具业发展相当快,目前,塑料模具在整个模具行业中约占30%左右,而在整个塑料模具市场以注塑模具需求量最大。随着模具制造行业的发展,许多企业开始追求提高产品质量及生产效率,缩短设计周期及制造周期,降低生产成本,最大限度地提高模具制造业的应变能力等目标。新兴的模具CAD技术很大程度上实现了企业的愿望。近年来,CAD技术的应用越来越普遍和深入,大大缩短了模具设计周期,提高了制模质量和复杂模具的制造能力。目前,美国、日本、德国等工业发达国家模具工业的产值均已超过机床工业总产值。美国模具年产值已超过100亿美元;日本从1957年到1984年二十七年间,模具工业增长100倍;1987年台湾地区模具出口达一亿二千万美元。香港的模具年产值为30亿港币,我国的模具年产值为人民币30亿元。从整体来看,中国塑料模具无论是在数量上,还是在质量、技术和能力等方面都有了很多进步,但与国民经济发展的需求、世界先进水平相比,差距仍然很大。主要缺陷明显的表现在精度不高,技术含量低、复杂程度低等缺点。严重的阻碍着国内模具业的发展。一些大型、精密、复杂、长寿命的中高档塑料模具每年仍需大量进口。在总量供不应求的同时,一些低档塑料模具却供过于求,市场竞争激烈,还有一些技术含量不太高的中档塑料模具也有供过于求的趋势。因此中国塑料模具行业和国外先进水平相比,主要存在一下问题:发展不平衡,产品总体水平较低;工艺装备落后,组织协调能力差;大多数企业开发能力弱,创新能力明显不足;供需矛盾短期难以缓解;体制和人才问题的解决尚需时日。这些都严重的阻碍着国内电子业的发展。设计出好的产品却无法做出是我模具业的最大不足。因此,注重科技含量,借助了国外的先进理论技术则尤为重要。大型化、高精密度、节能复合型模具将是未来注塑模具的发展方向。随着国际化,市场竞争越来越激烈,短周期、高质量、长寿命的高档塑料模具也会加大研制与开发。同时,注塑模具将与并行工程、精益生产、敏捷制造等多种生产模式密切结合,最终使塑料模具行业发生重大变革。在工业高速变革的时期,更新模具技术成了关键的课题。 2、注塑模简介注塑成型又称注塑模具,是热塑性塑料制件的一种主要成型方法,并且能够成功地将某些热固性塑料注塑成型。注塑成型可成型各种形状的塑料制品,其优点包括成型周期短,能一次成型外形复杂、尺寸精密、带有嵌件的制品,且生产效率高易于实现自动化,因而广泛应用在塑料制品生产当中。3、注塑成型原理及特点塑料的注塑成型过程,就是借助螺杆或柱塞的推力,将已塑化的塑料熔体以一定的压力和速度注入模具型腔内,经过冷却固化定型后开模而获得制品。因此,可以说注塑成型在塑料装配生产中具有重要地位。4、注塑成型原理注塑成型所用的模具即为注塑模(也称为注射模),注塑成型的原理(以螺杆式注射机为例)。首先将颗粒或粉状的塑料加入料斗,然后输送到侧装有电加热的料筒中塑化。螺杆在料筒前端原地转动,使被加热预塑的塑料在螺杆的转动作用下通过螺旋槽输送至料筒前端的喷嘴附近。螺杆的转动使塑料进一步化,料温在剪切摩擦热的作用下进一步提高并得以均匀化。当料筒前端堆积的体对螺杆产生一定的压力时(称为螺杆的背压),螺杆将转动后退,直至整好的行程开关接触,从而使螺母与螺杆锁紧。具有模具一次注射量的塑料预塑和储过程结束。这时,马达带动气缸前进,与液压缸活塞相连接的螺杆以一定的速度和压力将熔料通过料筒前端的喷嘴注入温度较低的闭合模具型腔中。熔体通过喷嘴注入闭合模具腔后,必须经过一定时间的保压,熔融塑料才能冷却固化,保持模具型腔所赋予形状和尺寸。当合模机构打开时,在推出机构的作用下,即可顶出注塑成型的塑料制品。5、充电器外壳注塑模具设计注塑模具设计的流程:(1)思考与创新,绘制草图,确定充电器外壳的外观形式;(2)实践操作:通过Pro-e软件画出充电器外壳的三维模型; (3)用Pro-e做出内部的结构,实现外观要求;(4)将Pro-e做的图导入AutoCAD中;(5)修改结构图,优化结构图。6、注射模具的设计过程(1)对塑料零件的材料、形状和功能进行分析(2)确定型腔的数目 确定型腔的数目条件有:最大注射量、锁模力、产品的精度要求和经济性等。(3)选择分型面分型面的选择应以模具结构简单、分型容易,且不破坏已成型的塑件为原则。(4)型腔的布置方案型腔的布置应采用平衡式排列,以保证各型腔平衡进料。型腔的布置还要注意与冷却管道、推杆布置的协调问题。(5)确定浇注系统浇注系统包括主流道、分流道、浇口和冷料穴。浇注系统的设计应根据模具的类型、型腔的数目及布置方式、塑件的原料及尺寸等确定。(6)确定脱模方式脱模方式的设计应根据塑件留在模具的部分而同。由于注射机的推出顶杆在动模部分,所以,脱模推出机构一般都设计在模具的动模部分。因此,应设计成使塑件能留在动模部分。设计中,除了将较长的型芯安排在动模部分以外,还常设计拉料杆,强制塑件留在动模部分。但也有些塑件的结构要求塑件在分型时,留在定模部分,在定模一侧设计出推出装置。推出机构的设计也应根据塑件的不同结构设计出不同的形式,有推杆、推管和推板等结构。(7)确定调温系统结构模具的调温系统主要由塑料种类决定。模具的大小、塑件的物理性能、外观和尺寸精度都对模具的调温系统有影响。(8)确定凹模和型心的固定方式当凹模或型心采用镶块结构时,应合理地划分铁块并同时考虑镶块的强度、可加工性及安装固定。(9)确定排气尺寸一般注射模的排气可以利用模具分型面和推杆与模具的间隙;而对于大型和高速成型的注射模,必须设计相应的排气装置。(10)确定注射模的主要尺寸根据相应的公式,计算成型零件的工作尺寸,以及决定模具型腔的侧壁厚度、动模板的厚度、拼块式型腔的型腔板的厚度及注射模的闭合高度。(11)选用标准模架根据设计、计算的注射模的主要尺寸,来选用注视模的标准模架,并尽量选择标准模具零件。(12)绘制模具的结构草图在以上工作的基础上,绘制注射模的完整的结构草图,绘制模具结构图是模具设计十分重要的工作,其步骤为先画俯视图(顺序为:画模架、型腔、冷却管道、支撑柱、推出机构),再画出主视图。(13)校核模具与注射机有关尺寸对所使用的注射机的参数进行校核:包括最大注射量、注射压力、锁模力及模具的安装部分的尺寸、开模行程和推出机构的校核。(14)注射模结构设计的审查对根据上述有关注视模结构设计的各项要求设计出来的注射模,应进行注射模结构设计的初步审查,同时,也有必要对提出的要求加以确认和修改。(15)绘制模具的装配图装配图是模具装配的主要依据,因此应清楚地表明注视模的各个零件的装配关系、必要的尺寸(如外形尺寸、定位圈直径、安装尺寸、活动零件的极限尺寸等)、序号、明细表、标题栏及技术要求。(16)绘制模具的零件图由模具装配图拆绘零件图的顺序为:先内后外,先复杂后简单,先成型零件后结构零件。(17)复核设计图样注射模具设计的最后是审核所设计的注射模,应多关注零件的加工、性能。7、已查阅的文献资料1 李学峰.塑料模设计及制造.M.北京:机械工业出版社,20012 翁其金.塑料模塑成型技术. M.北京:机械工业出版社,2002.3 冯炳尧等.模具设计与制造简明手册(第二版)M.上海科学技术出版社,2008.4 钱泉森.塑料成型工艺及模具设计. M.济南:山东科学技术出版社,20045 塑料模设计手册编著组.塑料设计手册.北京:机械工业出版社,20026 陈剑鹤.模具设计基础. M.北京:机械工业出版社,20047 王文广等.塑料注塑模具设计技巧与实.M.北京:化学工业出版社,20048 章飞.型腔模具设计与制造. M.北京:化学工业出版社,20039 田宝善等.塑料注射模设计实例及技巧. M.北京:化学工业出版社,200910 朱光.塑料注塑模中小型模架及其技术条件.M.北京:清华大学出版社,200311 宋满仓等.注塑模具设计. M.北京:电子工业出版社,201012 许鹤峰.注塑模设计要点与图例. M.北京:化学工业出版社,200313 cunha,L,et.al.,performance of chromium nitride and titanium nitride coatings during platics injection moulding. Surface and coating Technology,2002.153(2-3):p.160-165.现有设备及实验条件:计算机一台,使用软件为Pro/Engineer5.0及Auto CAD2008、Moldflow insight,以上实验条件可满足本次毕业设计的要求。3、 实施方案、进度实施计划及预期提交的毕业设计资料一、2013年12月17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;二、2013年1月6日至2014年1月13日,开展调研,了解塑件结构,对原材料进行分析,考虑塑件的成型工艺性、模具的总体结构的形式,并完成部分英文摘要翻译。三、2014年3月4日至2013年3月31日,查阅资料,熟悉注射模的结构及有关计算,拟定模具的方案设计、总体设计及主要零件设计,拟定成型工艺过程,查阅有关手册确定适宜的工艺参数,注射机的选择及确定注射设备及型号规格;四、2014年4月1日至2014年4月21日,完成设计计算任务,总体结构的设计和完成总装配图及零件图的设计;五、2014年4月22日至2014年5月1日,完成设计,图纸绘制任务,工艺规程说明书的编写;六、2014年5月1日至2014年5月4日,完善设计并完成论文的撰写;七、2014年5月4日至2014年5月8日,修改并打印毕业论文及整理相关资料,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- 6 - 桂林电子科技大学毕业设计(论文)报告用纸 编号: 毕业设计(论文)外文翻译(原文)学 院: 国防生学院 专 业:机械设计制造及其自动化学生姓名: 郑 波 学 号: 1000110532 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 1 月 12 日EFFECTS OF CUTTING EDGE GEOMETRY,WORKPIECE HARDNESS, FEED RATE AND CUTTING SPEED ON SURFACE ROUGHNESS AND FORCES IN FINISH TURNING OF HARDENED AISI H13 STEEL Tugrul zel, Tsu-Kong Hsu, Erol Zeren Department of Industrial and Systems Engineering Rutgers, The State University of New Jersey, New Jersey 08854 USA AbstractIn this study, effects of cutting edge geometry, workpiece hardness, feed rate and cutting speed on surface roughness and resultant forces in the finish hard turning of AISI H13 steel were experimentally investigated. Cubic boron nitrite inserts with two distinct edge preparations and through-hardened AISI H-13 steel bars were used. Four factor (hardness, edge geometry, feed rate and cutting speed)- two level fractional experiments were conducted and statistical analysis of variance was performed. During hard turning experiments, three components of tool forces and roughness of the machined surface were measured. This study shows that the effects of workpiece hardness, cutting edge geometry, feed rate and cutting speed on surface roughness are statistically significant. The effects of two-factor interactions of the edge geometry and the workpiece hardness, the edge geometry and the feed rate, and the cutting speed and feed rate are also appeared to be important. Especially, small edge radius and lower workpiece surface hardness resulted in better surface roughness. Cutting edge geometry, workpiece hardness and cutting speed are found to be affecting force components. The lower workpiece surface hardness and small edge radius resulted in lower tangential and radial forces.1. INTRODUCTION Hard turning, machining ferrous metal parts that are hardened usually between 45-70 HRC, can be performed dry using polycrystalline cubic boron nitride (PCBN, commonly CBN) cutting tools as extensively reported in literature 1-8. Research results in the literature concerning mechanism of serrated chip formation in order to relate process characteristics and stability of cutting to the chip shapes during hard turning 9-19. Other research concerning with composition, temperatures and wear characteristics of CBN cutting tools 1,8,20,21,22,28 and effects of work material properties, tool geometry and cutting conditions on surface integrity of the finish machined parts 23-28 indicate challenges in hard turning and identifies various process, equipment and tooling related factors affecting surface quality, tool life and productivity. After reviewing the literature, factors affecting forces, tool wear/failure and roughness and integrity of the finished surfaces in hard turning using CBN cutting tools and their influences on each other are illustrated with a chart shown in Fig. 1. In this chart, the parameters above the horizontal dashed lines are considered as factors or inputs to the hard turning process and they can only be selected in the beginning except tool vibration. All other parameters, that are located below these dashed lines, considered as performance measures or outputs of the hard turning process. Review of the literature reveals that almost all of the factors given in this chart affect performance of the hard turning process. Those factors can be classified as follows:1.1 Cutting tool geometry and material propertiesHard turning with CBN cutting tools demands prudent design of tool geometry. CBN cutting tools have lower toughness than other common tool materials, thus chipping ismore likely 2. Therefore, a nose radius and proper edge preparation are essential to increase the strength of cutting edge and attain favorable surface characteristics on finished metal components 23. CBN cutting tools designed for hard turning feature negative rake geometry and edge preparation (a chamfer or a hone, or even both). Specifications of the edge preparation design are often finalized after extensive experimentation. Fig. 2 shows the types of edge preparations common for CBN cutting tools. According to recent studies, it is evident that effect of edge geometry on surface quality is significant 23-28.Fig. 1. A flow chart illustrating relationships of factors in hard turning.Theile et al. 24, 25, presented research results of an experimental investigation of effects of cutting edge geometry and workpiece hardness on residual stresses in finish hard turning of AISI 52100 steel. They indicated that both factors are significant for the surface integrity of finish hard turned components. Specifically, they showed that large hone radius tools produce more compressive stresses, but also leave “white-layers”. zel 26 investigated the influence of edge geometry in CBN tools with respect to stress and temperature development through finite element simulations in hard turning. Chou et al. 28 experimentally investigated the influence of CBN content on surface quality and tool wear in hardened AISI 52100 steel tool. This study concluded that low content CBN tools produce better surface roughness with respect to higher content CBN tools and depth of cut has minor effect on tool wear rate.Fig. 2. Type of edge preparations for CBN cutting tools.1.2 Workpiece hardness Due to the changes in properties of hardened workpiece material, basic shearing process and formation of chips differ in hard turning 5. Prior research showed that workpiece hardness has a profound effect on the performance of the CBN tools 1,2,8 and also integrity of finish machined surfaces 23,25. Matsumoto et al. 23 and Thiele et al. 25 studied the effect of workpiece hardness on residual stresses. In a recent study, Guo and Liu 27 investigated material properties of hardened AISI 52100 bearing steel using temperature controlled tensile tests and orthogonal cutting tests and demonstrated that hardness greatly influences the material properties accounting for high variation in flow stress properties.1.3 Cutting speed, feed rate and depth of cut Performance of CBN cutting tools is highly dependent on the cutting conditions i.e. cutting speed, feed, feed-rate, and depth of cut 7. Especially cutting speed and depth of cut significantly influence tool life 22. Increased cutting speed and depth of cut result in increased temperatures at the cutting zone. Since CBN is a ceramic material, at elevated temperatures chemical wear becomes a leading wear mechanism and often accelerates weakening of cutting edge, resulting in premature tool failure (chipping), namely edge breakage of the cutting tool. In addition, Thiele et al. 24 noticed that when feed rate is increased, residual stresses change from compressive to tensile. 1.4 Surface integrity, residual stresses and tool wear In general, residual stresses become more compressive as workpiece hardness increases. The hardness and fracture toughness of CBN tools decrease with reduced CBN content 8. Owing to ceramic binder phase, CBN-L tools have a lower thermal conductivity, which causes increasing temperatures of cutting edge during hard turning. Chou and Barash 9 reported that CBN-L tools are more suitable for finish turning of hardened steel. At low cutting speeds, tool life of CBN-L is superior to CBN-H, whereas at higher cutting speeds, the reverse is true, and also surface roughness is less favorable when using CBN-H tool 28. Thiele et al. 24 reported that residual stresses generated by large edge hone tools are typically more compressive than stresses produced by small edge hone tools and they also leave white-layers. In addition, the effects of edge geometry play an important role in thermoplastic deformation of the workpiece. Koenig et al. 3 reported that an increase in feed rate raises the compressive residual stress maximal and deepens the affected zone. It was also suggested that the chamfer is unfavorable in terms of attainable surface finish when compared to honed or sharp edges.1.5 Accuracy and rigidity of the machine tool Another parameter that is often ignored is tool vibration. In order to reduce tool vibration it is necessary provide sufficiently rigid tool and workpiece fixtures. Assuring that there is minimal tool vibration is an easy way to improve surface roughness. It is also necessary that the tooling system be extremely rigid to withstand the immense cutting forces. It is well known that the radial force is the largest among force components during hard turning. Many researchers indicated that extremely rigid, high power, and high precision machine tools are required for hard turning because CBN tools are brittle and prone to chipping 3, 7, 8, 14, 23. It is also suggested that having higher rigidity in machine tool-clamping-tooling system achieves better surface quality on the part. It is well known that vibration and chatter are important problems that degrade part quality and tool performance. To improve the overall efficiency of finish hard turning, it is necessary to have a complete process understanding. To this end, a great deal of research has been performed in order to quantify the effect of various hard turning process parameters to surface quality. In order to gain a greater understanding of the hard turning process it is necessary to understand the impact of each of these variables, but also the interactions between them. It is impossible to find all of the variables that impact surface quality in finish hard turning. In addition, it is costly and time-consuming to discern the effect of every variable on the output.2. EXPERIMENTAL PROCEDURE 2.1 Workpiece material The workpiece material used in this study was AISI H13 hot work tool steel, which is used for high demand tooling. The cylindrical bar AISI H13 specimen that are utilized in this experiments had a diameter of 1.25 inches and length of 2 feet. The bar specimens were heat treated (through-hardened) at in-house heat treatment facility in order to obtain the desired hardness values of 50 and 55 HRC. However, the subsequent hardness tests by using Future Tech Rockwell type hardness tester revealed that the actual hardness of each specimen was 51.31.0 and 54.70.5 HRC. Henceforth, the hardness values are defined by the mean values of the measured workpiece hardness. 2.2 Tooling and edge geometry CBN inserts with two distinct representative types of edge preparations were investigated in this study. These edge preparations include: a) “chamfered” (T-land) edges and b) “honed” edges as illustrated in Fig.2. Solid top CBN inserts (TNM-433 and GE Superabrasives BZN 8100 grade) inserts were used with a Kennametal DTGNR-124B right hand tool holder with 00 lead and 50 rake angles. Honed and chamfered insert edge geometry were measured in coordinated measurement machine with three replications using a high precision touch-trigger probe. For the honed inserts, an average radius of 10.5 4.0 m was found. Chamfered insert edge geometry was found to have 200 chamfer angle and 0.1 0.03 mm chamfer width using same instruments with three replications and was approximated to an equivalent hone radius of 101.6 5.1 m. 2.3 Experimental design A four factor two level factorial design was used to determine the effects of the cutting edge geometry, workpiece hardness, feed rate and cutting speed on surface roughness and resultant forces in the finish hard turning of AISI H 13 steel. The factors and factor levels are summarized in Table 1. These factor levels results in a total of 16 unique factor level combinations. Sixteen replications of each factor level combinations were conducted resulting in a total of 256 tests. Each replication represents 25.4 mm cutting length in axial direction. The response variables are the workpiece surface roughness and the cutting forces.Longitudinal turning was conducted on a rigid, high-precision CNC lathe (Romi Centur 35E) at a constant depth of cut at 0.254 mm. The bar workpieces were held in the machine with a collet to minimize run-out and maximize rigidity. The length of cut for each test was 25.4 mm in the axial direction. Due to availability constraints, each insert were used for one factor level combination, which consisted of 16 replications. (A total of three honed and three chamfer inserts were available). In this manner each edge preparation was subject to the same number of tests and the same axial length of cut. Finally, surface roughness and tool wear measurements were conducted when the cutting length reached 203.2 mm (8 inches) and 406.4 mm (16 inches) during each factor level combination. The surface roughness was measured with a Taylor-Habson Surtronic 3+ profilometer and Mitutoyo SJ-digital surface analyzer, using a trace length of 4.8 mm, a cut-off length of 0.8 mm. The surface roughness values were recorded at eight equally spaced locations around the circumference every 25.4 mm distance from the edge of the specimen to obtain statistically meaningful data for each factor level combination. CBN inserts were examined using a tool-maker microscope to measure flank wear depth and detect undesirable features on the edge of the cutting tool by interrupting finish hard turning process. 2.4 Cutting force measurements The cutting forces were measured with a three-component force dynamometer (Kistler Type 9121) mount on the turret disk of the CNC lathe via a custom designed turret adapter (Kistler type 9121) for the toolholder creating a very rigid tooling fixture. The charge signal generated at the dynamometer was amplified using charge amplifiers (Kistler Type 5814B1). The amplified signal is acquired and sampled by using data acquisition PCMCIA card and Kistler DyanoWare software on a laptop computer at a sampling frequency of 2000 Hz per channel. Time-series profiles of the acquired force data reveal that the forces are relatively constant over the length of cut and factors such as vibration and spindle run-out were negligible. Three components of the resultant force are shown schematically in Fig. 3. Fig. 3. Measured cutting-force components.3. RESULTS AND DISCUSSION An analysis of variance (ANOVA) was conducted to identify statistically significant trends in the measured surface roughness and cutting force data. Separate ANOVA analyses were conducted for Ra surface roughness values and for each component of the cutting force i.e. axial (feed), radial (thrust), and tangential (cutting) forces. Additionally, plots of significant factors corresponding to each ANOVA analysis were constructed. These plots provide a more in-depth analysis of the significant factors related to the surface roughness and cutting forces in finish hard turning of AISI H13 steel using chamfered and honed CBN inserts.3.1 ANOVA results ANOVA tables for Ra surface roughness parameters are given in Table 2. In addition to degree of freedom (DF), mean square (MS) and F values (F) the table shows the P-values (P) associate with each factor level and interaction. A low P-value indicates an indication of statistical significange for the source on the response. Table 2 show that the main effects of edge geometry, cutting speed and feed rate except hardness, interactions between edge geometry and hardness, feed rate, and cutting speed, the interactions between cutting speed and feed rate are significant to surface roughness. Feed rate is the dominant parameter associated with the surface roughness. This is expected because it is well known that the theoretical surface roughness is primarily a function of the feed for a given nose radius and varies as the square of the feed rate 8.The radial force is usually the largest, tangential force is the middle and the axial (feed) force is the smallest in finish hard turning. In general, cutting force components are influences by cutting speed, edge geometry and feed rate. Tables 3-5 are ANOVA tables corresponding to the radial, axial (feed force) and tangential components of the cutting force, respectively. These tables show that the main effects of workpiece hardness, the edge geometry, cutting speed and feed rate (except for axial force) are all significant with respect to the forces in the radial, axial and tangential directions.Table 3 shows that the main effects of the edge geometry, cutting speed, hardness and the interactions between edge geometry and hardness, cutting speed, feed rate are significant with respect to the forces in the axial (feed) direction. Axial (feed) force is not much influence by the change in feed rate. Table 4 shows that the main effects of the edge geometry, cutting speed, hardness and only the interactions between edge geometry and cutting speed, feed rate are significant with respect to the forces in the radial direction.Table 5 shows that the main effects of the edge geometry, cutting speed, hardness, feed and only the interactions between edge geometry and hardness, cutting speed, feed rate are significant with respect to the forces in the tangential direction.3.2 Effect of feed rate and edge preparation on surface roughness Graphs of Ra surface roughness parameters are shown in Figures 4 and 5. These figures have been constructed to illustrate the main effects of edge geometry and feed rate parameters on the surface roughness. Based on the previous analysis, the main effect of the interaction between edge geometry and feed rate are found to be statistically significant on surface roughness Ra. Fig. 4 shows the effect of edge geometry and feed rate on the Ra surface roughness parameter for 54.7 HRC, cutting speed 200 m/min and cutting length of 406.4 mm. Fig. 5 shows the effect of edge geometry and feed rate on the Ra surface roughness parameter for 51.3 HRC with cutting speed of 100 m/min and cutting length of 25.4 mm.Fig. 4. Effect of cutting edge geometry and feed rate on surface roughness (high levels).Fig. 5. Effect of cutting edge geometry and feed on surface roughness (low levels).These two figures show that all edge preparations are confounded at the lowest feed rate (0.05mm/rev). However, the large edge radius resulted in better surface roughness when higher hardness and cutting speed selected, whereas it is the opposite when lower hardness and cutting speed selected. Finally, it should be noted that the main effect due to feed is readily apparent for each edge preparation. Specifically, the surface roughness increases as the feed rate increases as the surface roughness being proportional to the square of the feed rate. 3. 3 Effect of surface hardness and edge preparation on surface roughness Fig. 6 is constructed to illustrate the main effects of edge geometry and surface hardness parameters on the surface roughness with cutting speed 200 m/min, feed rate 0.2 mm/rev and cutting length 406.4 mm. Based on the previous analysis, the main effect of the interaction between edge geometry and workpiece surface hardness are statistically significant to surface roughness Ra parameters. The figure shows that small edge radius and lower workpiece surface hardness resulted in better surface roughness.Fig. 6. Effect of cutting edge geometry and hardness on surface roughness.3.4 Effect of surface hardness and edge preparation on tangential, radial and axial (feed) forces Graphs of the force components as functions of edge geometry and workpiece surface hardness are shown in Figs. 7-9. These figures show that chamfered edge geometry and higher workpiece surface hardness result in hig
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