锥齿轮的注塑模具设计【一模四腔】【说明书+CAD】
购买设计请充值后下载,资源目录下的文件所见即所得,都可以点开预览,资料完整,充值下载可得到资源目录里的所有文件。【注】:dwg后缀为CAD图纸,doc,docx为WORD文档,原稿无水印,可编辑。具体请见文件预览,有不明白之处,可咨询QQ:12401814
河南机电高等专科学校学生毕业设计(论文)中期检查表学生姓名学 号指导教师选题情况课题名称锥齿轮的注塑模设计难易程度偏难适中偏易工作量较大合理较小符合规范化的要求任务书有无开题报告有无外文翻译质量优良中差学习态度、出勤情况好一般差工作进度快按计划进行慢中期工作汇报及解答问题情况优良中差中期成绩评定:所在专业意见: 负责人: 年 月 日锥齿轮的注塑模设计绪 论慕具是制造业的重要工艺基础,在我国,模具制造属于专用设备制造业。中国虽然很早就开始制造模具和使用模具,但长期未形成产业。直到20世纪80年代后期,中国模具工业才驶入发展的快车道。近年,不仅国有模具企业有了很大发展,三资企业、乡镇(个体)模具企业的发展也相当迅速。虽然中国模具工业发展迅速,但与需求相比,显然供不应求,其主要缺口集中于精密、大型、复杂、长寿命模具领域。由于在模具精度、寿命、制造周期及生产能力等方面,中国与国际平均水平和发达国家仍有较大差距,因此,每年需要大量进口模具。近年,模具行业结构调整和体制改革步伐加大,主要表现在,大型、精密、复杂、长寿命、中高档模具及模具标准件发展速度高于一般模具产品;塑料模和压铸模比例增大;专业模具厂数量及其生产能力增加;“三资”及私营企业发展迅速;股份制改造步伐加快等。从地区分布来看,以珠江三角洲和长江三角洲为中心的东南沿海地区发展快于中西部地区,南方的发展快于北方。目前发展最快、模具生产最为集中的省份是广东和浙江,江苏、上海、安徽和山东等地近几年也有较大发展。1存在问题和主要差距虽然我国模具总量目前已达到相当规模,模具水平也有很大提高,但设计制造水平总体上落后于德、美、日、法、意等工业发达国家许多。当前存在的问题和差距主要表现在以下几方面:总量供不应求国内模具自配率只有70%左右。其中低档模具供过于求,中高档模具自配率只有50%左右。企业组织结构、产品结构、技术结构和进出口结构均不合理我国模具生产厂中多数是自产自配的工模具车间(分厂),自产自配比例高达60%左右,而国外模具超过70%属商品模具。专业模具厂大多是“大而全”、“小而全”的组织形式,而国外大多是“小而专”、“小而精”。国内大型、精密、复杂、长寿命的模具占总量比例不足30%,而国外在50%以上。2004年,模具进出口之比为3.71,进出口相抵后的净进口额达13.2亿美元,为世界模具净进口量最大的国家。模具产品水平大大低于国际水平,生产周期却高于国际水平产品水平低主要表现在模具的精度、型腔表面粗糙度、寿命及结构等方面。开发能力较差,经济效益欠佳我国模具企业技术人员比例低,水平较低,且不重视产品开发,在市场中经常处于被动地位。我国每个模具职工平均年创造产值约合1万美元,国外模具工业发达国家大多是1520万美元,有的高达2530万美元,与之相对的是我国相当一部分模具企业还沿用过去作坊式管理,真正实现现代化企业管理的企业较少。2造成上述差距的原因很多,除了历史上模具作为产品长期未得到应有的重视,以及多数国有企业机制不能适应市场经济之外,还有下列几个原因:国家对模具工业的政策支持力度还不够虽然国家已经明确颁布了模具行业的产业政策,但配套政策少,执行力度弱。目前享受模具产品增值税的企业全国只有185家,大多数企业仍旧税负过重。模具企业进行技术改造引进设备要缴纳相当数量的税金,影响技术进步,而且民营企业贷款十分困难。人才严重不足,科研开发及技术攻关投入太少模具行业是技术、资金、劳动密集的产业,随着时代的进步和技术的发展,掌握并且熟练运用新技术的人才异常短缺,高级模具钳工及企业管理人才也非常紧张。由于模具企业效益欠佳及对科研开发和技术攻关重视不够,科研单位和大专院校的眼睛盯着创收,导致模具行业在科研开发和技术攻关方面投入太少,致使模具技术发展步伐不大,进展不快工艺装备水平低,且配套性不好,利用率低近年来我国机床行业进步较快,已能提供比较成套的高精度加工设备,但与国外装备相比,仍有较大差距。虽然国内许多企业已引进许多国外先进设备,但总体的装备水平比国外许多企业低很多。由于体制和资金等方面的原因,引进设备不配套,设备与附件不配套现象十分普遍,设备利用率低的问题长期得不到较妥善的解决。专业化、标准化、商品化程度低,协作能力差由于长期以来受“大而全”“小而全”影响,模具专业化水平低,专业分工不细致,商品化程度低。目前国内每年生产的模具,商品模具只占40左右,其余为自产自用。模具企业之间协作不畅,难以完成较大规模的模具成套任务。模具标准化水平低,模具标准件使用覆盖率低也对模具质量、成本有较大影响,特别是对模具制造周期有很大影响。模具材料及模具相关技术落后模具材料性能、质量和品种问题往往会影响模具质量、寿命及成本,国产模具钢与国外进口钢材相比有较大差距。塑料、板材、设备性能差,也直接影响模具水平的提高。3发展展望目前,我国经济仍处于高速发展阶段,国际上经济全球化发展趋势日趋明显,这为我国模具工业高速发展提供了良好的条件和机遇。一方面,国内模具市场将继续高速发展,另一方面,模具制造也逐渐向我国转移以及跨国集团到我国进行模具采购趋向也十分明显。因此,放眼未来,国际、国内的模具市场总体发展趋势前景看好,预计中国模具将在良好的市场环境下得到高速发展,我国不但会成为模具大国,而且一定逐步向模具制造强国的行列迈进。“十一五”期间,中国模具工业水平不仅在量和质的方面有很大提高,而且行业结构、产品水平、开发创新能力、企业的体制与机制以及技术进步的方面也会取得较大发展。模具技术集合了机械、电子、化学、光学、材料、计算机、精密监测和信息网络等诸多学科,是一个综合性多学科的系统工程。模具技术的发展趋势主要是模具产品向着更大型、更精密、更复杂及更经济的方向发展,模具产品的技术含量不断提高,模具制造周期不断缩短,模具生产朝着信息化、无图化、精细化、自动化的方向发展,模具企业向着技术集成化、设备精良化、产批品牌化、管理信息化、经营国际化的方向发展。我国模具行业今后仍需提高的共性技术有:(1)建立在CAD/CAE平台上的先进模具设计技术,提高模具设计的现代化、信息化、智能化、标准化水平(2)建立在CAM/CAPP基础上的先进模具加工技术与先进制造技术相结合,提高模具加工的自动化水平与生产效率。(3)模具生产企业的信息化管理技术。例如PDM(产品数据管理)、ERP(企业资源管理)、MIS(模具制造管理信息系统)及INTERMET平台等信息网络技术的应用、推广及发展。(4)高速、高精、复合模具加工技术的研究与应用。例如超精冲压模具制造技术、精密塑料和压铸模具制造技术等。(5)提高模具生产效率、降低成本和缩短模具生产周期的各种快速经济模具制造技术。(6)先进制造技术的应用。例如热流道技术、气辅技术、虚拟技术、纳米技术、高速扫描技术、逆向工程、并行工程等技术在模具研究、开发、加工过程中的应用。(7)原材料在模具中成形的仿真技术。(8)先进的模具加工和专有设备的研究与开发。(9)模具及模具标准件、重要辅件的标准化技术。(10)模具及其制品的检测技术。(11)优质、新型模具材料的研究与开发及其正确应用。(12)模具生产企业的现代化管理技术。第1章 模塑工艺规程的编制1.1 塑件的工艺性分析塑件的工艺性分析包括塑件的原材料分析,塑件的尺寸精度分析,塑件的表面质量和塑件的结构工艺性分析,其具体分析如下。1.1.1 塑件的原材料分析表1 塑件的原材料分析5塑料品种结构特点使用温度化学稳定性性能特点成型特点聚碳酸酯(pc),属于热塑性塑料线型结构非结晶型材料,透明小于130,耐寒性好,脆化温度位-100有一定的化学稳定性,不耐碱、酮、酯等透光率较高,介电性能好,吸水性小,但水敏性强(含水量不得超过0.2%),且吸水后会降解力学性能很好,抗冲击抗蠕变性能突出,但耐磨性较差熔融温度高(超过330才严重分解),但熔体黏度大;流动性差(溢边值为0.06mm);流动性对温度变化敏感,冷却速度快;成型收缩率小;易产生应力集中 结论 熔融温度高且熔体黏度大,应严格控制模具温度,一般在70120为宜,模具应用耐磨刚,并淬火。 水敏性强,加工前必须干燥处理,否则会出现银丝、气泡及强度显著下降 易产生应力集中,严格控制成型条件;塑件壁不宜厚,避免有尖角、缺口和金属嵌件造成应力集中,脱模斜度宜取21.1.2 塑件的尺寸精度分析该塑件的主要尺寸有其特定的要求,其余尺寸都为自由尺寸,按MT5查取公差,所以其精度不是很高,易成型,其主要尺寸公差标注如下(单位均为mm): 塑件的外形尺寸:, 塑件的内形尺寸:,1.1.3 塑件表面质量分析与金属零件一样,塑件的表面质量对它的使用性能是有影响的。塑件强度与它的表面粗糙度有直接关系。表面显微不平的凹陷正是应力集中处,且凹陷愈深,它的半径愈小,则应力集中就愈大,因此强度就愈差。另外粗糙度大的塑件表面的耐腐蚀就差些。由于锥齿轮在传动过程中防止过早失效,所以该塑件的外形粗糙度取Ra=0.4 ,而塑件内部没有较高的表面粗糙度要求。1.1.4 塑件的结构工艺性分析从图纸上分析:该塑件整体外形为回转体,且符合最小壁厚要求,壁厚也较均匀。综上所述,该塑件可采用注射成型加工。1.2 计算塑件体积和质量1.2.1计算塑件的体积 V=2026.61mm(经估算所得,过程略)1.2.2 计算塑件的质量计算塑件的质量是为了选择注塑机及确定模具型腔数,根据有关手册查得:=1.2kg/dmPC的密度,所以塑件的质量 M=v=1.2102026.61 =2.43 g根据塑件形状及尺寸采用“一出四”,即一模四腔。考虑外形尺寸,对塑件原材料的分析以及注射所需的压力情况,参考模具设计手册初选螺杆式注射机:XS-ZY-250。1.3 塑件模塑成型工艺参数的确定聚碳酸酯注射成型工艺参数见表 2 ,试模时,可根据实际情况做适当的调整表2 聚碳酸酯注射成型工艺参数工艺参数规格工艺参数规格预热和干燥温度:110120成型时间/s注射时间2090时间:812 h保压时间05料筒温度t/ 后段210240冷却时间2090中段230280总周期40190前段240285模具温度t/70120喷嘴温度t/240250注射压力P/MPa80110第2章 注塑模的结构设计注射模结构设计主要包括:分型面的选择,模具型腔数目的确定及型腔的排列,浇注系统的设计,型芯、型腔结构的确定,推件方式的确定。2.1 分型面的选择 该塑件为锥齿轮,由于其使用性能要求,其外观要求美观,无斑点和熔接痕,表面质量要求较高,并且齿轮的齿廓与孔的同轴度要求也比较高。根据分型面的选择原则,分型面选在齿轮的最大截面A-A处,如图2所示: 图1 分型面的选择这样也有利于浇注系统的排列和模具的平衡。2.2 确定模具型腔数目及排列方式 由于该塑件采用的是一模四件成型,所以考虑到模具成型零件和出模方式的设计,模具的型腔排列方式如下图3所示:图2型腔的排列2.3 确定浇注系统2.3.1 主流道设计 根据手册查得XS-ZY-125型注射机喷嘴的有关尺寸: 喷嘴球半径:R0=12mm 喷嘴孔直径:d0=4mm 根据模具主流道与喷嘴的关系:R=R0+(12)mm,d=d0+0.5mm 取主流道球面半径:R=14mm 取主流道的小端直径:d=4.5mm为了便于将凝料从主流道中拔出,将主流道设计成圆锥形,其斜度为13。经换算得主流道大端直径D=12mm。同时为了使熔料顺利进入分流道,在主流道出料端设计r=5mm的圆弧过渡。主流道的尺寸直接影响到熔体的流动速度和冲模时间。由于主流道要与高温塑料熔体及主注射机喷嘴反复接触,所以在注射模中主流道部分常设计成可拆卸更换的浇口套形式。主流道的长度L一般按模板的厚度确定,一般控制在60mm以下。2.3.2 分流道的设计 分流道的形状及尺寸与塑件的体积,壁厚,形状的复杂程度,注射速率等因素有关。该塑件的体积不是很大,形状不算太复杂,且壁厚较均匀。为了便于加工方面的考虑,采用截面形状为半圆形的分流道。查有关手册得R=6mm2.3.3 浇口设计A 浇口形式的选择由于该塑件外观质量要求较高,浇口的位置和大小应以不影响塑件的外观质量为前提。同时,也应尽量使模具结构更简单,所以成型该塑件的模具采用点浇口的形式B 进料位置的确定根据塑件外观质量的要求以及型腔的安放方式,进料位置设计在塑件的底部。2.3.4 冷料穴的设计 冷料穴位于主流道政对面的动模板上或者处于分流道的末端,其作用是收集熔体前锋 的料,防止冷料进入模具型腔而影响制品的质量。冷料穴的长度通常为流道直径d的1.52.0倍。所以冷料穴长度L=9mm。设置在熔体流动方向的转折位置,并迎着上游的熔体流向。其结构如下图4所示:图3 冷料穴2.4 成型零件的结构设计2.4.1 凹模的结构设计由于塑件的形状比较复杂,所以采用热处理变形小的40Cr ,采用整体式。这样便于加工和制造。2.4.2 凸模的结构设计 考虑模具温度调节系统的设置,型芯采用整体式结构,采用热处理变形小的CrWMn。2.5 顶出机构的设计 2.5.1 推件方式的选择 根据塑件的形状特点,模具型腔在定模部分。开模后,由于塑料的收缩,塑件包在型芯上留在动模一侧,其推出机构可采用推管推出或顶杆顶出。其中,推管推出结构可靠,顶出力均匀,不影响塑件的外观质量,而由于锥齿轮的结构所限,采用顶杆顶出,其顶杆无法放置。 从以上分析得出:该塑件采用推管推出机构。并且从塑件图上可知,其脱模行程不大,所以采用长型芯的方式,即型芯紧固在模具底板上。而推管壁厚与塑件的壁厚一样,由前面的可知其壁厚为3.5mm,在1.5mm以上。推管的材料与推杆一样采用45#钢,其滑动长度的淬火硬度为50HRC左右,表面粗糙度达Ra0.631.25m。其具体结构及尺寸如附图所示。2.5.2 复位装置的选择 由于该模采用的是推管脱模,在将塑件顶出后,必须返回其原始位置,才能合模进行下一次的注塑成型。该模采用回程杆的方式来进行推管的回复。回程也是标准件。只需买来即能使用。2.5.3 导向装置的选择 由于塑件的要求不是很高,所以不需设置设置导向装置,用回程杆来进行导向既可满足要求。2.6 对合导向机构的设计 对合导向机构的功能三保证动定模部分能够准确对合,使分别加工在动模和定模上的成型表面在模具闭合后形成形状和尺寸准确的腔体,从而保证塑件形状,壁厚和尺寸的准确,该模具采用导柱对合导向机构。导柱和型芯一起安装在动模一侧,这样在合模时可起保护作用。 导柱,导套的结构形式的选择:导柱的结构形式采用阶梯形导柱,这样当导柱工作部分翘曲时,容易从模板中卸下更换,采用4根直径相同的导柱不对称的方式来进行布置。而导套则采用有肩导套。 导柱和导套都是标准件,从外面买进就可直接使用。2.7 点浇口凝料的脱出 由前面可知该模具采用点浇口,为了将浇注系统凝料取出,需要增加一个分型面。这种结构的浇注系统凝料一般是人 工取出的,因此模具结构简单,但是生产率低,劳动强度大,只用于小批量生产,为适应自动化的要求该模具采用侧凹拉断点浇口凝料的方法来取出浇注系统的凝料。其主要方法是在分流道尽头钻一斜孔(侧凹8),开模时由于斜孔内冷凝塑料的限制,浇注系统凝料在浇口处与塑件拉断,容后由于主流道冷料井的拉料杆(6)的作用,钩住浇注系统凝料脱离浇口套,当主流道完全退出浇口套后,在限位拉杆的作用下,拉动定模板将浇注系统凝料从拉了杆中脱出。他们的结构关如下图5所示。 拉料杆采用带10的圆形侧凹的拉料杆,并且为了便于凝料的脱出,其与冷料穴的结构如下图4所示:图4 浇注系统凝料的脱出1浇口套;2拉料杆;3上模座;4定模板;5动模板;6型芯;7推管;8侧凹2.8 确定排气系统的形式:当塑料填充型腔时,必须排出浇注系统内的空气及塑料受热产生的气体,以保证塑件不会由于填充不足而出现气泡、接缝或表面轮廓不清等缺点;甚至气体受压力形成高温使塑料焦化。但是此制件比较小采用分型面间隙排气即可。第3章 模具设计的有关计算3.1 成型零件的尺寸计算 该塑件的成型零件尺寸均按平均值法计算。查有关手册可知PC的收缩率为0.5%0.7%。故平均收缩率为SCP=(0.5+0.7)%/2=0.6%=0.006。根据塑件尺寸工差要求,模具的制造公差取=/43.1.1 型芯主要工作尺寸的计算 根据塑件图可知型芯主要成型2个轴孔。其尺寸计算见表3表3型芯主要工作尺寸的计算已知条件:平均收缩率SCP=0.006mm;=/4;X-系数,按表4.4-6查取1;为塑件公差类别塑件尺寸(mm)计算公式型芯的工作尺寸(mm)型芯的计算 3.1.2 型腔主要工作尺寸的计算 根据塑件图,型腔主要成型锥齿轮的齿廓以及齿轮的高度,型腔不仅要考虑在直径方向上的收缩,还应考虑在切向方向上齿厚上的收缩,但从上塑件图上可知该齿轮较小,加工较困难,所以可以不考虑齿厚上的收缩。型腔的主要工作尺寸以齿顶圆锥为计算基准。其主要工作尺寸见下表4:表4 型腔的主要工作尺寸的计算类别塑件尺寸(mm)计算公式型芯的工作尺寸(mm)型腔的计算230.1422.970.043.2 型腔侧壁厚度及底板厚度的计算 3.2.1 型腔侧壁厚度的计算该模具型腔为整体式的圆形型腔,根据整体式圆形型腔侧壁厚度计算公式 进行计算。 =6.09mm 式中:-材料的许用应力,=300N/mm2 -模腔压力;=60MPa r-型腔内孔的半径 考虑到该型腔为整体式,为了便于制造取型腔侧壁厚度为15mm。3.2.2 型腔底板厚度计算根据整体式型腔地板厚度计算公式进行计算。 =8.13mm考虑模具的整体结构的协调取,H=32mm。第4章 模具加热与冷却系统的计算注射模不仅是塑料熔体的成型设备,而且还是热交换器,模温调节系统直接关系塑件的质量和生产效率,是注射模设计的核心内容之一。在注射成型过程中,塑料熔体所释放的热量约有5%30%由模具传导,对流和辐射的方式散发到大气中,热量大部分由冷却水带走,模具的冷却时间约占整个注射循环周期的2/3。 由于聚碳酸酯的熔融粘度高,流动性差,所以需要较高的模温,若模温过低,则会影响塑料的流动性,产生较大的流动剪切力,使塑件的内应力较大,甚至会出现冷流痕,银丝,注不满等缺陷。所以需要对模具进行加热。该模具采用加热中插入电加热棒的加热方法进行对模具的加热。4.1 加热功率的计算根据电加热功率计算的经验公式:=89.325 =2232.5(W)式中:G-模具的重量,经估算得G=89.3; q-为加热单位重量模具至所需温度的电功率,查表得q=25(w/)4.2 电加热棒根数的计算及在模具上的布置考虑模板的尺寸,在该模具上布置4根电加热棒,所以其功率的计算如下: =2232.5/4=558.125 (W) 所以选用4根25300mm的加热棒。其位置见附图。第5章 模具闭合高度的确定本塑件采用点浇口注射成型,根据结构形式,选择P1型。根据前面的计算,模架的周边尺寸为315mm315mm导柱:32mm100mm40mm()GB/T 4196.5-1984导套:32mm32mmGB/T 4169.2-7984复位杆:在支撑与固定零件的设计中,根据经验确定:定模座板:=40mm 定模板:=32mm 动模板:=25mm 垫 块:=80mm 凸模固定板:=20mm 动模座板:=25mm所以模具的闭合高度: 第6章 注塑机有关参数校核6.1 模具安装部分的校核该模具的外形尺寸为400mm355mm,XS-ZY-250型注射机模板最大安装尺寸为598520,故能满足模具安装要求。由于XS-ZY-250型注射机所允许模具的最小厚度为=165mm,最大厚度=350mm。所以也满足模具安装要求。6.2 模具开模行程的校核经查资料注射机XS-ZY-250型的最大开模行程S=350mm,满足下式计算所需的出件要求: 所以,XS-ZY-250型注射机能满足使用要求,故可以采用。第7章 绘制模具总装图和非标准零件工作图本模具的总装图见装配图所示。非标准件图见零件图。本模具的工作原理:模具安装在注塑机上,定模部分固定在注塑机的定模板上,动模固定在注塑机的动模板上。合模后,注塑机通过喷嘴将熔料经流道注入型腔,经保压、冷却后塑件成型。开模时动模部分随动模板一起运动渐渐将分型面打开,型芯随动模一起运动,塑件依附在型芯上。型芯随型芯固定板5运动一定距离后停止运动,此时推件板20在注射机顶杆的驱动下向前运动使塑件渐渐脱离型芯。合模时,随着分型面的逐渐闭合推动复位杆恢复原位。第8章 模具的安装与调试8.1模具的安装装配顺序如下:(1) 装配前按图检验主要工作零件及其他零件的尺寸。(2) 镗导柱孔,将定模板7,动模板5,定模座板8合在一起,使分模面紧密接触并夹紧。镗导柱孔,型孔,在空内压入工艺定位销后,加工侧面的垂直基准。(3) 加工定模,用定模侧面的垂直基准确定定模7上型腔中心的实际位置,并以此作为加工基准,对其进行电火花穿孔加工,将锥齿轮的四个型腔成型出来,然后加工出浇口套孔以及四个拉料杆孔。(4) 加工动模,按定模实际加工中心位置在动模板5上加工出四个推管孔以及型腔,然后加工出四个复位杆孔。(5) 压入导柱。在定模座板8,定模板7以及动模板5上分别压入导柱,并检查其垂直度,使导向可靠,滑动灵活。 (6) 装配型芯。先将型芯固定板2,动模板5,推杆固定板21以及推板22合拢,把型芯10放入推管9孔内,然后把推管9放入动模板5的型控内,用螺孔复印法和压销钉套法使推管以及型芯紧固在型芯固定板2上。(7) 通过动模板5引钻推杆固定板上21的复位杆孔。(8) 组装动模座板1,型芯固定板2,垫块以及动模板5。(9) 在推杆固定板21和动模板5上加工限位螺钉孔。(10) 定模和定模座板的装配。用平行夹头把它们夹紧,通过定模板7的孔引钻在定模上,拆开后,再定模上钻,拉料杆孔,然后将定模7和定模座板8紧固。(11) 装配动模部分,修正推杆和复位杆长度。(12) 完成装配后进行试模,并校验入库。8.2 模具的调试:注射模装配成以后。也要按正常的生产条件进行试模,以了解模具的实际使用性能是否满足生产要求、有无不完善的地方进行改进或作调整。通过试模塑件上常会出现各种弊病,为此必须进行原因分析,排除故障。造成次废品的原因很多,有时是单一的,但经常是多个方面综合的原因。需按成型条件,成型设备,模具结构及制造精度,塑件结构及形状等因素逐个分析找出其中主要矛盾,然后再采取调节成型条件,修整模具等方法加以解决。首先,在初次试模中我们最常遇到的问题是根本得不到完整的样件。常因塑件被粘附于模腔内,或型芯上,甚至因流道粘着制品被损坏。这是试模首先应当解决的问题。在试模过程中,应做详细记录,并将结果填入试模记录卡,注明模具是否合格。如需返修,则应提出返修意见。在记录卡中应摘录成型工艺条件及操作注意要点,最好能附加上加工出的制件,以供参考。试模后,将模具清理干净,涂上防锈漆,然后分别入库和返修。设计总结毕业设计是一项非常繁杂的工作,它涉及的知识比较广泛,很多都是我们所学课本上没有的东西,这就要靠自己去图书馆查找自己所需要的资料;还有很多设计计算,这些都要靠自己运用自己的思维能力去解决,可以说,完成这样复杂的工作需要一定的毅力和耐心。在学校中,我们主要学的是理论性的知识,而实践性很欠缺,而毕业设计就相当于实战前的一次演练。通过毕业设计可是把我们以前学的专业知识系统的连贯起来,使我们在温习旧知识的同时也可以学习到很多新的知识;这不但提高了我们解决问题的能力,开阔了我们的视野,在一定程度上弥补我们实践经验的不足,为以后的工作打下坚实的基础。本设计设计内容为锥齿轮塑料模设计,通过对锥齿轮的设计,基本掌握了对塑料模设计的方法及步骤,对塑料模有了更进一步的了解和认识,对模具的制造方法和制造途径积累了一定的经验。 由于水平有限,很多知识掌握的不是很牢固,因此在设计中难免要遇到很多难题,由于有了课程设计老师的不吝指导和同学的热心帮助下,克服了一个又一个的困难,使我的毕业设计日趋完善。本设计中模板等尺寸也不代表一种最佳的选择,例如模板的厚度,可以根据能取得的原料的厚度按最小的加工量选择(要满足最小厚度要求,同时也不能太厚太重)。同一塑件由不同的人设计有多种多样的方案,最终都有可能很好的使用,通过这次设计,我认识到了除了正确掌握和应用书本知识外,吸取他人的设计经验也是非常重要的。致谢本设计在设计过程中得到了杨占尧、翟德梅、赵常海、原红玲、于智宏等几位指导老师的大力支持和帮助,再此表示诚挚的感谢,由于本人水平有限,收集资料困难,如果有不尽人意的地方,恳请导师不吝赐教,提出宝贵改进意见。参考文献1 杨占尧主编. 塑料注塑模结构与设计. 清华大学出版社, 200042 翟德梅主编. 模具制造技术. 20013 许发樾主编. 实用模具设计与制造手册. 机械工业出版社, 20004 陈锡栋 周小玉主编. 实用模具技术手册. 机械工业出版社, 20015 黄锐主编. 塑料工程手册. 机械工业出版社, 20006 贾润礼,程志远主编. 实用注塑模设计手册. 中国轻工业出版社, 20007 屈华昌主编. 塑料成型工艺与模具设计. 北京高等教育出版社, 20018 陈万林主编. 实用注塑模设计与制造. 北京机械工业出版社, 20009 张克慧主编. 注塑模设计. 西北工业大学出版社, 200110 马金俊主编. 注塑模具设计. 中国科学技术出版社, 1994第 23 页 共 23 页Microsystem Technologies 10 (2004) 531535 _ Springer-Verlag 2004DOI 10.1007/s00542-004-0387-2Replication of microlens arrays by injection moldingB.-K. Lee, D. S. Kim, T. H. KwonB.-K. Lee, D. S. Kim, T. H. Kwon (&)Department of Mechanical Engineering,Pohang University of Science and Technology (POSTECH),San 31, Hyoja-Dong, Nam-Gu, Pohang, 790-784, Koreae-mail: thkwonpostech.ac.krAbstract Injection molding could be used as a mass production technology for microlens arrays. It is of importance, and thus of our concern in the present study, to understand the injection molding processing condition effects on the replicability of microlens array profile. Extensive experiments were performed by varyingprocessing conditions such as flow rate, packing pressure and packing time for three different polymeric materials (PS, PMMA and PC). The nickel mold insert of microlens arrays was made by electroplating a microstructure master fabricated by a modified LIGA process. Effects of processing conditions on the replicability were investigated with the help of the surface profile measurements. Experimental results showed that a packing pressure and a flow rate significantly affects a final surface profile of the injection molded product. Atomic force microscope measurement indicated that the averaged surface roughness value of injection molded microlens arrays is smaller than that of mold insert and is comparable with that of fine optical components in practical use.1 Introduction Microoptical products such as microlenses or microlens arrays have been used widely in various fields of microoptics, optical data storages, bio-medical applications, display devices and so on. Microlenses and microlens arrays are essential elements not only for the practical applications but also for the fundamental studies in the microoptics. There have been several fabrication methods for microlenses or microlens arryas such as a modified LIGA process 1, photoresist reflow process 2, UV laser illumination 3, etc. And the replication techniques, such as injection molding, compression molding 4 and hot embossing 5, are getting more important for a mass production of microoptical products due to the cost-effectiveness. As long as the injection molding can replicate subtle microstructures well, it is surely the most cost-effective method in the mass production stage due to its excellent reproducibility and productivity. In this regard, it is of utmost importance to check the injection moldability and to determine the molding processing condition window for proper injection molding of microstructures. In this study, we investigated the effects of processing conditions on the replication of microlens arrays by the injection molding. The microlens arrays were fabricated by a modified LIGA process, which was previously reported in 6, 7. Injection molding experiments were performed with an electroplated nickel mold insert so as to investigate the effects of some processing conditions. The surface profiles of molded microlens arrays were measured, and were used to analyze effects of processing conditions. Finally, a surface roughness of microlens arrays was measured by an atomic force microscope (AFM).2 Mold insert fabricationMicrolens arrays having several different diameters were fabricated on a PMMA sheet by a modified LIGA process 6. This modified LIGA process is composed of an X-ray irradiation on the PMMA sheet and a subsequent thermal treatment. The X-ray irradiation causes the decrease of molecular weight of PMMA, which in turn decreases the glass transition temperature and consequently causes a net volume increase during the thermal cycle resulting in a swollen microlens 7. The shapes of microlenses fabricated by the modified LIGA process can be predicted by a method suggested in 7. The microlens arrays used in the experiments were composed of 500m -(a 2 2 array), 300m -(2 2) and 200m (5 5) diameter arrays, and their heights were 20.81, 17.21 and 8.06 m, respectively. Using the microlens arrays fabricated by the modified LIGA process as a master, a metallic mold insert was fabricated by a nickel electroplating for the injection molding. Typical materials used in a microfabrication process, such as silicon, photoresists or polymeric materials, cannot be directly used as the mold or the mold insert due to their weak strength or thermal properties. It is desirable to use metallic materials which have appropriate mechanical and thermal properties to endure both a high pressure and a large temperature variation during the replication process. Therefore, a metallic mold insert is being used rather than the PMMA master on silicon wafer for mass production with such replication techniques. Otherwise special techniques should be adopted as a replication method, e.g. a low pressure injection molding 8.The size of final electroplated mold insert was 30 30 3 mm. The electroplated nickel mold insert having microlens arrays is shown in Fig. 1.Fig.1.Moldinsert fabricated by a nickel electroplating (a) Real view of the mold insert (b) SEM image of 200 m diameter microlens array (c) SEM image of 300 mdiameter microlens array3 Injection molding experimentsA conventional injection molding machine (Allrounders 220 M, Arburg) was used in the experiments. A mold base for the injection molding was designed to fix the electroplated nickel mold insert firmly with the help of a frametype bolster plate (Fig. 2). Shape of aperture of the bolster plate (in this study, a rectangular one) defines the outer geometry of the molded part on which the profiles of microlens arrays are to be transcribed. The mold base itself has delivery systems such as sprue, runner and gate which lead the molten polymer to the cavity formed by the bolster plate, the mold insert and amoving mold surface. The mold base was designed such that mold insert replacement is simple and easy. Of course, one may introduce an appropriate bolster plate with a specific aperture shape. Fig. 2. Mold base and mold insert used in the injection molding experimentThe injection molding experiments were carried out with three general polymeric materials PS (615APR, Dow Chemical), PMMA (IF870, LG MMA) and PC (Lexan 141R, GE Plastics). These materials are quite commonly used for optical applications. They have different refractive indices (1.600, 1.490 and 1.586 for PS, PMMA and PC, respectively), giving rise to different optical properties in final products, e.g. different foci with the same geometry. The injectionmolding experiments were performed for seven processing conditions by changing flow rate, packing pressure and packing time for each polymeric material. Furthermore, same experiments were repeated three times for checking the reproducibility. It may be mentioned that the mold temperature effect was not considered in this study since the temperature effect is relatively less important for these microlens arrays due to their large radius of curvature than other microstructures of high aspect ratio. For high aspect ratio microstructures, we are currently investigating the temperature effect more closely and plan to report separately in the future. Therefore, flow rate, packing pressure and packing time were varied to investigate their effects more thoroughly with the mold temperature unchanged in this study. Table 1 shows the detailed processing conditions for three polymeric materials. Other processing conditions were kept unchanged during the experiment. The mold temperatures were set to 80, 70 and 60 _C for PC, PMMA and PS, respectively.It might be mentioned that we carried out the experiments without a vacuum condition in the mold cavity considering that the large radius of curvature of the microlens arrays in the present study will not entrap air in the microlens cavity during the filling stage.Table 1. Detailed processing conditions used in the injection molding experimentsCaseFlow rate (cc/sec)Packing time (sec)Packing pressure(MPa)112.05.010.0212.05.015.0312.05.020.0PS412.02.010.0512.010.010.0618.05.010.0724.05.010.0PMMA16.010.010.026.010.015.036.010.020.046.05.010.05676.09.012.015.010.010.010.010.010.0PC 16.05.05.026.05.010.0356.06.09.05.010.015.05.065.05.0712.05.05.04Results and discussionBefore detailed discussion of the experimental results, it might be helpful to summarize why flow rate, packingpressure and packing time (which were chosen as processing conditions to be varied in this study) affect thereplication quality. As far as the flow rate is concerned, there may exist an optimal flow rate in the sense that too small flow rate makes too much cooling before a complete filling and thus possibly results in so-called short shot phenomena whereas too high flow rate increases pressure fields which is undesirable.The packing stage is generally required to compensate for the volume shrinkage of hot molten polymer whencooled down, so that enough material should flow into a mold cavity during this stage to control the dimensionalaccuracy. The higher the packing pressure, the longer the packing time, more material tends to flow in. However, too much packing pressure sometimes may cause uneven distribution of density, thereby resulting in poor opticalquality. And too long packing time does not help at all since gate will be frozen and prevent material from flowing into the cavity. In this regard, one needs to investigate the effects of packing pressure and packing time.4.1Surface profilesFigure 3 shows typical scanning electron microscope (SEM) images of the injection molded microlens arrays for different diameters for PMMA (a) and different materials (b). Cross-sectional surface profiles of the mold insert and all the injection molded microlens arrays were measured by a 3D profile measuring system (NH-3N, Mitaka).Fig. 3. SEM images of theinjection molded microlensarrays and microlenses (a)Injection molded microlensarrays (PMMA) (b) Injectionmolded microlenses of 300 mdiameter for different materialsAs a measure of replicability, we have defined a relative deviation of profile as the height difference between the molded one and the corresponding mold insert for each microlens divided by the mold insert one. The computed relative deviations for all the microlenses are listed in Table 2.Diameter ( m)Relative deviation (%)1234567PS200300500-7.625.862.38-7.592.03-0.382.082.860.51-5.611.47-8.6660161.47-11.444.291.47-5.731.95PMMA2003005007.205.77-0.661.315.60-1.62-3.886.453.98-5.805.952.80-0.975.95-0.72-8.536.68-0.904.86-2.62-0.72PC20030050023.026.20-0.9316.054.965.0916.872.66-1.8619.664.531.8833.974.786.9618.671.792.43-2.944.15-1.55It may be mentioned that the moldability of polymeric materials affects the replicability. Therefore, the overall relative deviation differs for three polymeric materials used in this study. It may be noted that PC is the most difficult material for injection molding amongst the three polymers. The largest relative deviation can be found in PC for the smallest diameter case, as expected. In that specific case, the largest value is corresponding to the low flow rate and low packing pressure. Packing time in this case does not significantly affect the deviation. The relative deviation for PS and PMMA with the smallest diameter is far better than PC case.Table 2 indicates that the larger the diameter, the smaller the relative deviation. The larger diameter microlens is, of course, easier to be filled than smaller diameter during the filling stage and packing stage. Microlenses of larger diameters were generally replicated well regardless of processing conditions and regardless of materials. The best replicability is found for the case of PS with 500 m diameter. Generally, PS has a good moldability in comparison with PMMA and PC.It may be mentioned that some negative values of relative deviation were observed mostly in the smallest diameter case for PS and PMMA according to Table 2. In these cases, however, the absolute deviation is an order of 0.1 m in height, which is within the measurement error of the system. Therefore, the negative values could be ignored in interpreting the experimental data of replicability. Surface profiles of microlens of 300 m diameter are shown in Figs. 4 and 5 for PC and PMMA, respectively. As shown in Fig. 4, the higher packing pressure or the higher flow rate results in the better replication of microlens for the case of PC, as mentioned above. Packing time has little effect on the replication for these cases. For the case of PMMA, the packing pressure and packing time have insignificant effect as shown in Fig. 5; however, flow rate has the similar effect to PC. It might be reminded that packing time does not affect the replicability if a gate is frozen since frozen gate prevents material from flowinginto the cavity. Therefore, the effect of packing time disappears after a certain time depending on the processing conditions.Fig.4ac(leftside).Surface profiles of microlens (PC with diameter (/) of 300 m). a effect of packing pressure, b effect of flow rate, c effectof packing timeFig.5ac.(rightside)Surface profiles of microlens (PMMA with diameter(/) of 300 m). a effect of packing pressure, b effect of flow rate,c effect of packing time4.2Surface roughnessAveraged surface roughness, Ra, values of 300 m diameter microlenses and the mold insert were measured by an atomic force microscope (Bioscope AFM, Digital Instruments). The measurements were performed around the top of each microlens and the measuring area was 5 m 5 m. Figure 6 shows AFM images and measured Ra values of microlenses. PMMA replicas of microlens have the lowest Ra value, 1.606 nm. It may be noted that AFM measurement indicated that Ra value of injection molded microlens arrays is smaller than the corresponding one of the mold insert. The reason for the improved surface roughness in the replicated microlens arrays is not clear at this moment, but might be attributed to the reflow caused by surface tension during a cooling process. It may be further noted that the Ra value of injection molded microlens arrays is comparable with that of fine optical components in practical use.Fig. 6. AFM images and averaged surface roughness, Ra, values of the mold insert and injection molded 300 m diameter microlenses. a Nickel mold insert, b PS, c PMMA, d PC4.3Focal lengthThe focal length of lenses can be calculated by a wellknown equation as follows:where f, nl, R1 and R2 are focal length, refractive index of lens material, two principal radii of curvature, respectively.For instance, focal lengths of the molded microlenses were approximately calculated as 1.065 mm (with R1 0.624 mm and R2 11 ¥) for 200 m diameter microlens, 1.130 mm (with R1= 0.662 mm and R2=) for 300 m microlens and 2.580 mm (with R1=1.512 mm and R2=) for 500 m microlens according to Eq. (1). These calculations were based on an assumption that microlenses are replicated with PC (nl= 1.586) and have the identical shape of the mold insert. It might be mentioned that the geometry of the molded microlens might be inversely deduced from an experimental measurement of the focal length.5ConclusionThe replication of microlens arrays was carried out by the injection molding process with the nickel mold insert which was electroplated from the microlens arrays master fabricated via a modified LIGA process.The effects of processing conditions were investigated through extensive experiments conducted with various processing conditions. The results showed that the higher packing pressure or the higher flow rate is, the better replicability is achieved. In comparison, the packing time was found to have little effect on the replication of microlens arrays.The injection molded microlens arrays had a smaller averaged surface roughness values than the mold insert, which might be attributed to the reflow induced by surface tension during the cooling stage. And PMMA replicas of microlens arrays had the best surface quality (i.e. the lowest roughness value of Ra =1.606 nm). The surface roughness of injection molded microlens arrays is comparable with that of fine optical components in practical use. In this regard, injection molding might be a useful manufacturing tool for mass production of microlensarrays.References1. Ruther P; Gerlach B; Gottert J; Ilie M; Muller A; Omann C (1997) Fabrication and characterization of microlenses realized by a modified LIGA process. Pure Appl Opt 6: 6436532. Popovic ZD; Sprague RA; Neville Connell GA (1988) Technique for monolithic fabrication of microlens array. Appl Opt27: 128112843. Beinhorn F; Ihlemann J; Luther K; Troe J (1999) Micro-lens arrays generated by UV laser irradiation of doped PMMA. Appl Phys A68: 7097134. Moon S; Lee N; Kang S (2003) Fabrication of a microlens array using micro-compression molding with an electroformed mold insert. J Micromech Microeng 13: 981035. Ong NS; Koh YH; Fu YQ (2002) Microlens array produced using hot embossing process. Microelectron Eng 60: 3653796. Lee S-K; Lee K-C; Lee SS (2002) A simple method for microlens fabrication by the modified LIGA process. J MicromechMicroeng 12: 3343407. Kim DS; Yang SS; Lee S-K; Kwon TH; Lee SS (2003) Physical modeling and analysis of microlens formation fabricated by a modified LIGA process. J Micromech Microeng 13: 5235318. Bauer W; Knitter R; Emde A; Bartelt G; Gohring D; Hansjosten E (2002) Replication techniques for ceramic microcomponents with high aspect ratio. Microsyst Technol 7: 85 90 微透镜阵列注塑成型的复制 B.-K. Lee, D. S. Kim, T. H. Kwon朴航科技大学(POSTECH) 机械工程学院San 31, Hyoja-Dong, Nam-Gu, Pohang, 790-784, Korea电子邮箱l: thkwonpostech.ac.kr摘要 微透镜阵列注塑成型,可作为一种非常重要的大量生产技术。因此我们在近来的研究中非常关注, 为了进一步了解注塑成型在不同的加工条件下对可复制的微透镜阵列剖面的影响,如流量、填料压力和填料时间,对3种不同的高分子材料(PS,PMMA和PC)进行了大量的试验。 镍金属模具嵌件微阵列就是利用改良的LIGA技术电镀主装配的显微结构制造的。在表面轮廓得到测量的前提下,研究工艺条件对可复制的微透镜阵列的影响。实验结果表明, 填料压力和流速对注射模塑的终产品的表面轮廓有重要的影响。 原子力显微镜测量表明, 微透镜阵列注塑成型的平均表面粗糙度值小于模具嵌件成型, 并在实际运用中,能与精细的光学元件相媲美。1 说明 微型光学产品,如微透镜或微透镜阵列已广泛应用于光学数据存储、生物医学、显示装置等各个光学领域。微透镜和微透镜阵列不仅在实践应用上,而且在微型光学的基础研究上都是非常重要的。有几种微透镜或微透镜阵列的制作方法,如改良的LIGA技术1 ,光阻回流进程2,紫外激光照射3等。还有复制技术,如注塑模压成型4和热压5技术 ,这种方法对于减少大规模生产的微型光学产品的成本尤为重要。由于其优越的生产和再生产能力,只要注塑成型过程中能很好的复制微观结构,那么肯定是最适合于降低大量生产成本的方法。基于这点,检查注塑成型能力并确定成型加工条件是注塑成型微观结构过程中最重要的步骤。在本次研究中,我们考察了工艺条件对可复制的微透镜阵列的注射成型的影响。微透镜阵列是用之前介绍过6,7的改良的LIGA技术来编制的。注塑成型实验采用的是一种镀镍金属模具,来探讨了几种不同工艺条件对成型的影响。通过对微透镜阵列的表面轮廓测量,用来分析工艺条件产生的影响。最后,利用原子力显微镜(AFM)测量微透镜的表面粗糙度值的大小。2 模具嵌件的制造利用改良的LIGA技术6,在一个有机玻璃板上制造出具有几种不同直径微透镜阵列。此种技术是先用X光照射有机玻璃板,然后再进行热处理两部分构成的。X-射线照射引起有机玻璃分子质量的减少,同时降低了玻璃化转变温度,并因此导致净含量的增加,在热循环的作用下,微透镜发生微膨胀7。利用7中提出的方法,结合改良的LIGA技术可以预测微透镜形状的变化过程。 在试验中使用的微透镜阵列,有500m (22阵列),300m (22)和200m (55)的直径阵列,高分别是20.81m,17.21m和8.06m。采用改良的LIGA技术制造微透镜阵列作为一个主要的技术,用来制作镀镍的金属模具的注塑成型。另一些特殊材料,因为它们的强度不够或热性能差而不能直接进行微细加工,当作模具或金属模具使用,如硅、光阻剂或高分子材料。尽量使用具有良好机械性能和热性能的金属材料,因为它们能在可复型加工过程中经受高压力和不断变化的温度。因此,为了利用这种复制技术进行大批量生产,我们选择使用金属模具材料而不是有机玻璃硅晶体。一些特殊技术,如低压注塑成型8技术,应该作为良好的复制加工方法被采纳。电镀模具的最终大小为30 mm30 mm3mm。镀镍金属模具所具有的微透镜阵列如图1所示。图1 镀镍模具嵌件的制造 (a)直接观察;(b)直径为200m的微透镜阵列电子显微镜图像;(c)直径为300m的微透镜阵列电子显微镜图像3 注塑成型实验 传统注塑机(Allrounders 220 M,Arburg)多用做实验机。注塑模具设计的模架就是利用一块框形支撑板固定镀镍模具(如图2所示)。
收藏