手机后盖注塑模具设计
手机后盖注塑模具设计,手机,注塑,模具设计
微透镜阵列注塑成型技术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,光阻回流进程,紫外激光照射等。还有复制技术,如注塑模压成型和热压技术 ,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,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。利用中提出的方法,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)。 图2 注塑模具实验中使用的模架和嵌件用修改的微透镜阵列确定模具零件孔形加强板(在这次实验中,是一块矩形板)的外部形状。模架本身已含有传输系统,如注射口,流道及浇口,通过支撑板、模具流道和滑动的模具表面将熔融聚合物引入模腔。用这种方法设计的模架,能够使模具零件更换起来简单容易。不过,有时候也使用具有特定孔径形状的支撑板。 实验主要用三种普通高分子材料,PS(615APR,陶氏化学),有机玻璃(IF870, LG MMA)和PC(Lexan 141R)进行注塑成型。这些高分子材料通常在光学元件上使用,它们有不同的折射率(PS,PMMA和PC的折射率分别为1.600,1.490和1.586),能生产出具有不同的光学特性的产品,例如:具有相同的几何尺寸却有不同的焦距的光学元件。通过改变每个高分子材料的流速,充填压力和充填时间获得7种加工条件进行注塑成型试验。此外,为了检查是否能可再生产,同一实验往往需要重复三次。可能有人会指出,实验中没有考虑模具温度的影响,这是因为温度效应相对来说不是主要因素,而且微透镜阵列曲率半径比其他微观结构的高宽纵横比大。正是因为较大的微观结构高宽纵横比,使我们目前研究的温度效应更加可靠,并计划在将来实验时进行单独报告。 因此,在这项研究中,我们保持模具温度不变,而流速、充填压力和充填的时间都变化的情况下,能更清楚的观察其产生效果。表1详细的列出了三种高分子材料PC,PMMA和PS在其他加工条件都保持不变,将模具温度分别设定为80,70和60的情况下的实验结果。表1注塑模具实验中详细的工艺条件序号流 速 (cc/s)充填时间 (/s)充填压(MPa)112.05.010.0212.05.015.0312.05.020.0PS412.02.010.0512.010.010.0618.05.010.0724.05.010.0PMMA16.010.010.026.010.015.036.010.020.046.05.010.0566.09.015.010.010.010.0续表1序号流 速 (cc/s)充填时间 (/s)充填压力(MPa)712.010.010.0PC 16.05.05.026.05.010.0356.06.09.05.010.015.05.065.05.0712.05.05.0可能有人会指出,我们的实验没有考虑型腔出现真空状态时的情况,其实大可不必担心,因为在本研究中的注射阶段,大曲率半径的微透镜阵列不会把空气引入到型腔中。4 讨论和结果在详细讨论实验结果之前,认真思考一下,可能有助于总结为什么流速、充填压力和充填时间(在这项研究中被选为不同的加工条件)影响复制的质量。就流速而言,可能存在一个最佳流速,而在完成充填之前,流速太小会使得熔融聚合物过冷却,从而可能导致所谓的短暂的不连续现象,而过高的流速增大了压力面积,这是不可取的。充填阶段是一般要求,是要在冷却时能够弥补热熔融聚合物的体积收缩 。 因此,在这个阶段应有足够的熔融聚合物流入型腔并控制产品的尺寸精度。 越高的充填压力,越长的充填时间,将使更多的材料持续不断的流向型腔。然而, 过高的充填压力,有时可能造成不均匀的密度分布,从而产生劣质的光学质量。过长的充填时间,不利于在各自浇口处的冷凝,并且会阻止熔融聚合物流入型腔。因此,我们需要研究不同的充填压力和充填时间所产生的影响。4.1 表面轮廓图3所示的是用电子显微镜(SEM) 扫描的不同注塑微透镜的直径的PMMA图像(a)以及不同 材料的图像(b)。代表性的模具表面轮廓以及所有注塑微阵列都是通过三维轮廓测量系统(NH-3N, Mitaka)测定的。图3 注塑模具的微透镜阵列和微透镜的电子显微镜图像(a)PMMA微透镜阵列 (b)不同材料直径为300m微透镜阵列的注塑模具作为一个可复制阵列的测量工具,我们已经确定了在模具与相应的模具嵌件分开的微阵列之间轮廓的相对高度偏差,所有的微透镜阵列相对偏差值列在表2中,具体见表所示: 表2 表面轮廓相对偏差直径 (m)相对偏差(%)1234567PS200300500-7.625.862.38-7.592.03-0.382.082.860.51-5.565.611.47-8.6660.161.47-11.444.291.47-9.475.731.95PMMA2003005007.205.77-0.661.315.60-1.62-3.886.453.98-5.805.952.80-0.975.95-0.72-8.536.68-0.904.86-2.62-0.72PC20030050023.026.20-0.9316.054.965.0916.872.66-1.8619.664.531.8833.974.786.9618.671.792.43-2.944.15-1.55值得一提的是,高分子材料的塑性会影响其重复使用性能。 因此在研究中,三种高分子材料总的相对误差是各不相同的。PC是三种聚合物中最难注塑成型的材料。在直径最小的例子中产生最大的相对偏差,那都是意料之中的事。 在这种特殊情况下,充填时间并不对偏差产生显著影响,最好的解决方法是采用相对低的流速和充填压力。PS和PMMA最小的直径的相对偏差要比PC小的多。 从表2可以看出,直径越大,相对偏差越小。当然,在注射和保压阶段,直径大的微透镜阵列容易比直径小的更容易填补,不管是在什么加工条件下和使用什么材料,大直径的微透镜阵列一般都能得到较好的复型。研究发现直径500m的PS最好复型,一般而言,与PMMA和PC相比较,PS具有良好的成型性能。根据表2的数据,在考察最小的直径的PS和PMMA的相对偏差时,可能会有人提出一些消极的观点,认为偏差过大,但是在这些数据中可以得到,高度上的绝对偏差在0.1m左右,这是在测量系统误差范围以内。 所以,在解读复型实验数据时可以忽略这些消极的观点。 直径为300m的PC和PMMA微透镜表面轮廓分别如图4和图5所示。正如之前所述,在图4所示的PC中,越高的充填压力或越高流速复制微透镜时效果越好,而充填时间在这些复型例子中只起一点作用。如图所示,对于PMMA来说,充填压力和充填时间的作用微不足道;然而,流速对于PC也有类似的效果。 它可以提醒我们注意如果一个浇口冻结了,并阻止材料流入型腔时,充填时间并不影响复型。 因此,经过一段时间后,充填时间的影响,主要取决于加工条件。 图4 直径为300m的PC微透镜表面轮廓 a 充填压力的影响 b 流速的影响c 充填时间的影响 图5 直径为300m的PMMA微透镜表面轮廓a 充填压力的影响 b 流速的影响 c 充填时间的影响4.2 表面粗糙度直径300m的微透镜和模具嵌件的平均表面粗糙度Ra的值,是用原子力显微镜(Bioscope AFM,数字仪表) 测量的。测量了每个微透镜顶点周围面积为5m5m区域, 图6所示的是原子力显微镜图象和所测量的微透镜Ra的值。PMMA微透镜复型具有最低的Ra值,为1.606nm。通过AFM的测量表明,注塑成型微透镜阵列的Ra值比相对应的模具嵌件要小。 因此,现在还不清楚如何改善可复制微透镜阵列的表面粗糙度,也许可以从冷却过程的回流而造成的表面张力入手,它可能会进一步得出,在实际运用中,微透镜阵列注塑成型的平均表面粗糙度值能与精细的光学元件相媲美。a 镀镍模具嵌件; b PS; c PMMA; d PC图6 直径为300m的模具嵌件和注塑模具微透镜的原子力显微镜(AFM)图像和平均表面粗糙度Ra值 4.3 焦距 焦距可以通过下面这个著名的等式计算得出: 式中f,nl, R1和R2分别指焦距,透镜材料的折射率,两个主曲率半径。比如,根据等式可以计算得出,直径为200m的模具微透镜的焦距大约为1.065mm(其中R1=0.624mm和R2=),直径300的微透镜大约为1.130mm (其中R1=0.662mm和R2=),直径500m的微透镜大约为2.580mm(其中R1=1.512mm和R2=)。 (1)这些计算结果是基于假设与模具嵌件具有相同形状的PC(nl=1.586)可复型的微透镜而得到的,所以由此推导出的几何尺寸可能与实验所测量的焦距相反。5 总结 通过使用改良的LIGA技术电镀镍金属模具嵌件,改变各种加工条件进行大量的实验,研究工艺条件对可复型的微透镜的注塑成型过程的影响。结果显示越高的充填压力或越高流速,能得到越好的可复型效果。 相比之下,充填时间对微透镜阵列复型的影响却很小。也许是因为冷却阶段回流的表面张力造成的,注射成型微透镜阵列比模具嵌件有更小的平均表面粗糙度值,PMMA复型的微透镜阵列具有最好的表面质量(即最低粗糙度值Ra=1.606 nm)。在实际应用中,注塑成型微透镜阵列的表面粗糙度能与精密的光学元件相媲美。就凭这一点,注塑成型将成为大规模生产微透镜阵列的一个有用方法。11现代模具技术引言随着全球经济的发展,新的技术革命不断取得新的进展和突破,技术的飞跃发展已经成为推动世界经济增长的重要因素。市场经济的不断发展,促使工业产 品越来越向多品种、小批量、高质量、低成本的方向发展,为了保持和加强产品在市场上的竞争力,产品的开发周期、生产周期越来越短,于是对制造各种产品的关键工艺装备模具的要求越来越苛刻。 一方面企业为追求规模效益,使得模具向着高速、精密、长寿命方向发展; 另一方面企业为了满足多品种、小批量、产品更新换代快、赢得市场的需要,要求模具向着制造周期短、成本低的快速经济的方向发展。计算机、激光、电子、新材料、新技术的发展,使得快速经济制模技术如虎添翼,应用范围不断扩大,类型不断增多,创造的经济效益和社会效益越来越显著。1.注塑模具设计注塑成型使用温度依赖性改变材料性能,通过使用模具取得最后的形状离散部件完成或接近完成尺寸。在这种制造过程中,液体材料是被迫填入,在型腔模具内凝固。首先,要创造一个模式塑造需要一个设计模型和一个载箱。 首先,要创造一个模式塑造需要一个设计模型和一个载箱。设计模型代表了成品,而载箱代表模具组件的总体积。注塑模具设计涉及模具结构与功能的组成部分广泛的经验知识(启发式知识)。典型的过程中塑造新的发展可以分为四大阶段:产品设计,模具的能力评估,部件详细设计,插入型腔设计和详细的模具设计。在开始阶段,产品概念是在一起由几个人(通常是一个组合营销和工程)完成。开始阶段主要焦点是分析市场的机遇与适应战略。在第一阶段,典型相关工艺制造信息被添加到设计中,设计出几何细节。概念设计利用适当的制造信息转化为可制造的物品。在第二阶段,脱模方向和分型线位置用来检测模具的能力。否则,零件形状再次修改。在第三阶段,零件几何是用来建立模具的型芯和型腔形状,模具的型芯和型腔,将用来形成零件。一般,收缩和扩张需要加以考虑,这样,在处理温度下,成型将具有正确的尺寸和形状。浇口、流道、冷料穴、通风口也需要加以补充。几何数据和分模信息之间的联系在这一点是至关重要的。第四阶段与模具总体机械结构相关,模具总体机械结构包括连接模具到注塑机,注塑机是用于浇注、冷却、取出和模具装配的机械装置。零件的热处理工序,在使零件获得要求的硬度的同时,还需对内应力进行控制,保证零件加工时尺寸的稳定性,不同的材质分别有不同的处理方式。随着近年来模具工业的发展,使用的材料种类增多了,除了Cr12、40Cr、Cr12MoV、硬质合金外,对一些工作强度大,受力苛刻的凸、凹模,可选用新材料粉末合金钢,如V10、ASP23等,此类材质具有较高的热稳定性和良好的组织状态。针对以Cr12MoV为材质的零件,在粗加工后进行淬火处理,淬火后工件存在很大的存留应力,容易导致精加工或工作中开裂,零件淬火后应趁热回火,消除淬火应力。淬火温度控制在900-1020,然后冷却至200-220出炉空冷,随后迅速回炉220回火,这种方法称为一次硬化工艺,可以获得较高的强度及耐磨性,对于以磨损为主要失效形式的模具效果较好。生产中遇到一些拐角较多、形状复杂的工件,回火还不足以消除淬火应力,精加工前还需进行去应力退火或多次时效处理,充分释放应力。针对V10、APS23等粉末合金钢零件,因其能承受高温回火,淬火时可采用二次硬化工艺,1050-1080淬火,再用490-520高温回火并进行多次,可以获得较高的冲击韧性及稳定性,对以崩刃为主要失效形式的模具很适用。粉末合金钢的造价较高,但其性能好,正在形成一种广泛运用趋势。1.1.执行事实表明,SolidWorks的API接口采用了面向对象的方法和API函数允许选择对象语言,例如:作为编程语言的Visual C+。利用这种方法,在Windows NT下,基于Windows的注塑模具三维设计的应用软件通过Visual C+的代码与商业软件SolidWorks99接口开发。这个应用模具设计过程分为几个阶段,提供模具设计者制造模具设计可靠方法。图3概述了这个框架。每一个阶段可以视为一个独立程序模块。几个单元已成功使用SolidWorks开发.它们中的两个模板模块和分模模块如下所示。1.2 基于模架设计的模具基于模架设计的模具与所有的组件和配件,像HASCO,DME,HOPPT,LKM和FUTABA可自动创建参数化标准模板。设计师常用可以轻松地定制模板的这种模架。主要特点包括:像支柱、浇道衬套、两板,三板那样的标准模架组件的实用性,以及定制非标准模具模板基于。模架设计的模具分为四个主要部分,即构件库(包括标准和非标准件库),设计表中的尺寸驱动功能,结构关系管理。在这里,SolidWorks提供了尺寸驱动的功能是,以支持其申请。(1)组件库为了在这竞争日益激烈的世界加强模具设计能力,降低设计成本和缩短生产周期,减少人力、自动化等是达到这一目的主要因素。换句话说,使用计算机软件是非常必要的。 计算机软件能够容易地创建,修改,分析模具设计的部件,更新变化中的设计模型。为达到这个目标,三维构件库提供储存标准和非标准零部件的数据,其尺寸是储存在Microsoft Excel中 。通过指定合适的尺寸,这些组件可以生成和插入装配结构。 这个库是完全可定制和设计师能放入自己的部分加入组件库。表面处理及组配, 零件表面在加工时留下刀痕、磨痕是应力集中的地方,是裂纹扩展的源头,因此在加工结束后,需要对零件进行表面强化,通过钳工打磨,处理掉加工隐患。对工件的一些棱边、锐角、孔口进行倒钝,R化。一般地,电加工表面会产生6-10m左右的变质硬化层,颜色呈灰白色,硬化层脆而且带有残留应力,在使用之前要充分消除硬化层,方法为表面抛光,打磨去掉硬化层。在磨削加工、电加工过程中,工件会有一定磁化,具有微弱磁力,十分容易吸着一些小东西,因此在组装之前,要对工件作退磁处理,并用乙酸乙脂清洗表面。组装过程中,先参看装配图,找齐各零件,然后列出各零件相互之间的装备顺序,列出各项应注意事项,然后着手装配模具,装配一般先装导柱导套,然后装模架和凸凹模,然后再对各处间隙,特别是凸凹模间隙进行组配调整,装配完成后要实施模具检测,写出整体情况报告。对发现的问题,可采用逆向思维法,即从后工序向前工序,从精加工到粗加工,逐一检查,直到找出症结,解决问题。(2)尺寸驱动SolidWorks提供了强有力的尺寸驱动功能,以支持参数化设计。储存在Microsoft Excel中的尺寸和几何存在逻辑关系。当尺寸设置与相应物件几何参数设置相结合,可以获得确切的模型。(3)设计表设计表允许设计师在嵌入的Microsoft Excel 制表中通过具体参数建立多种零部件配置。设计表保存在零件文件夹,是用来存储的尺寸, 制止特点和性能配置, 其中包括在材料,组件和客户的要求中的零件数量。 当增加适当的尺寸,设计表将包含所有必要的信息,以建立一个精确的装配模型。(4)结构关系管理本部分讲述了组建模板之间的结构关系,从设计表供应的某些参数设置能帮助模具设计师插入这些部件装配结构, 因此,一个特定的装配模板就可以自动生成。1.3 分模模块一些分模算法以前就报导过。在这方面的发展,分模用来处理型芯和型腔。在注塑模具计算机辅助设计系统中,这是一个最重要的模块。设计一个模具模型需要有设计模型, 工件和有效分型面。设计模式体现了成品,而装载箱体现了模具组件的总量。为了把工件分成型芯和型腔,设计模型首先从工件中去除。然后用分模面把工件塑造成半,常指型芯和型腔。当熔融塑料射入型腔,模具对立的两面形成成品。凝固后,两半模子沿分模面d和d分别移开。然后获得了实际部分。(1) 分模方向决定型芯和型腔打开的相反两个方向就是分模方向,为了形成分型线,分模方向应首先确定。 分模方向影响分型线定位。分型线决定了模具的复杂度。 在大多数情况下, 分模方向是由几何和制造问题同时决定。(2) 识别和修补穿孔当产品中有穿孔,设计者必须标明孔的分模位置,在这些孔里边生成分型面。在这篇论文中,这就是所谓的补丁。表面都需要用来修补的通孔。 由于上模具和下模具在通孔处相连。如果没有事先修补通孔,模具是不能分开,型芯和型腔不能自动创建(见图6b)。(3) 确定分型线和顶出方向在成型中,模具的设计是提高模具质量的最重要的一步,需要考虑到很多因素,包括模具材料的选用,模具结构的可使用性及安全性,模具零件的可加工性及模具维修的方便性,这些在设计之初应尽量考虑得周全些。模具材料的选用既要满足客户对产品质量的要求,还需考虑到材料的成本及其在设定周期内的强度,当然还要根据模具的类型、使用工作方式、加工速度、主要失效形式等因素来选材.一组零件的表面由型芯塑造,而另一组是由型腔塑造。分型线因此是由型芯和型腔塑造的两组表面的相交线。分型线在表面组选择最大边缘线。从分型线到型芯或型腔边界,顶出方向在顶出过程中,分型线将会跟随。分型线是垂直于分模方向,平行于模具工件面的表面法线(见图 6c) 图(6)(4) 分型面生成分型面是型芯和型腔的匹配面。分型面可以作为分裂面把模具分成两半。两种方法可以用来生成分型面。席卷法:分型面通过顶出分型线到型芯和型腔外边界形成。拉伸方法:在SolidWorks中,分模面可以使用拉伸分模线到指定距离的方法创建,这个距离要足够大,大到可以沿伸到工件的外表面。(见图6e)(5) 工件的创建物件装入工件中,工件外围额外空间用计算机计算。工件大小由物件的几何大小、模具强度、模具参数决定。模具参数可以有效定义模具装配。(6) 型芯和型腔的生成为了生成型芯和型腔,工件被子分成两半。首先,设计模型从工件中取出。在工件内部获得一个空的空间。然后,分模面和修补面被使用把工件分成型芯块和型腔块。最后,在模拟模具开启过程和检查模具组件之间的干扰后,工件两半分别沿分模方向d和d从分模面分离(图6g)。2快速经济制模技术类型快速经济制模技术与传统的机械加工相比,具有制模周期短、成本低、精度与寿命又能满足生产上的使用要求,是综合经济效益比较显著的一类制造模具的技术,概括起来,有以下几种类别。2.1快速原型制造技术快速原型制造技术简称RPM,是80年代后期发展起来的一种新型制造技术。美国、日本、英国、以色列、德国、中国都推出了自己的商业化产品,并逐渐形成了新型产业。RPM是电脑、激光、光学扫描、先进的新型材料、计算机辅助设计(CAD)、计算机辅助加工(CAM)、数控(CNC)综合应用的高新技术。在成型概念上以平面离散、堆积为指导,在控制上以计算机和数控为基础,以最大柔性为总体目标。它摒弃了传统的机械加工方法,对制造业的变革是一个重大的突破,利用RPM技术可以直接或间接地快速制模,该技术已被汽车、航空、家电、船舶、医疗、模具等行业广泛应用。下面简述一下目前已经商业化的几种典型快速成型工艺。2.1.1激光立体光刻技术(SLA)SLA技术是交计算机CAD造型系统获得制品的三维模型,通过微机控制激光,按着确定的轨迹,对液态的光敏树脂进行逐层扫描,使被扫描区层层固化,连成一体,形成最终的三维实体,再经过有关的最终硬化打光等后处量,形成制件或模具。激光立体光刻技术主要特点是可成型任意复杂形状,成型精度高,仿真性强,材料利用率高,性能可靠,性能价格比较高。适合产品外型评估、功能实验、快速制造电极和各种快速经济模具。但该技术所用的设备和光敏树脂价格昂贵,使其成本较高。2.1.2叠层轮廓制造技术(LOM)LOM技术是通过计算机的三维模型,利用激光选择性地对其分层切片,将得到的各层截面轮廓层层粘结,最终叠加成三维实体产品。其工艺特点是成型速度快,成型材料便宜、成本低,因无相变,故无热应力、收缩、膨胀,翘曲等,所以形状与尽寸精度稳定,但成型后废料块剥离较费事,特别是复杂件内部的废料剥离。该工艺适用于航空、汽车等和中体积较大制件的制作。2.1.3激光粉末选区烧结成型技术(SLS)SLS技术是将计算机的三维模型通过分层软件将其分层,在计算机控制下,使激光束依据分层的切片截面信息对粉末逐层扫描,扫描到的粉末烧结固化(聚合、烧结、粘结、化学反应等),层层叠加,堆积成三维实体制件。该技术最大特点是能同时用几种不同材料(聚碳酸脂、聚乙烯氯化物、石蜡、尼龙、ABS、铸造砂)制造一个零件。2.1.4熔融沉积成型技术(FDM)FDM技术是由计算机控制可挤出熔融状态材料的喷嘴,根据CAD产品模型分层软件确定的几何信息,挤出半流动状态的热塑材料沉积固化成精确的实际制件薄层 ,自下而上层层堆积成一个三维实体,可直接做模具或产品。2.1.5三维印刷成型技术(3D-P)3D-P技术用微机控制一个连续喷墨印刷头,依据分层软件逐层选择性地在粉末层上沉积液体粘结材料,最终由顺序印刷的二维层堆积成一个三维实体,犹如不使用激光的快速制模技术。该技术主要应用在金属陶瓷复合材料的多孔陶瓷预成型件上,其目标是由CAD产品模型直接生产模具或功能性制作。2.2表面成型制模技术表面成型制模技术,主要是利用喷涂、电铸、化学腐蚀等新的工艺方法形成型腔表面及精细花纹的一种工艺技术,实际应用中包括以下几种类型。2.2.1电弧喷涂成型制模技术电弧喷涂成型技术的原理是:利用2根通电的金属丝之间产生电弧的热量将金属丝熔化,依靠高压气体将其充分雾化,并给予一定的动能,高速喷射在样模表面,层层镶嵌,形成一金属壳体,即型腔的内表面,再用充填基体材料(一般为金属粉粒与树脂的复合材料)加以支撑加固,提高其强度和刚性,连同金属模架组合成模具。这种制模技术工艺简单、成本低,制造周期非常短,型腔表面的成型仅需几个小时,节省能源和金属材料,一般型腔表面仅2-3mm厚,仿真性极强,花纹精度可达到0.5m。目前该技术被广泛地用于飞机、汽车的内饰件模具、家电、家俱、制鞋、美术工艺品等表面形状复杂及花纹精细的各种聚氨酯制品的吹塑、吸塑、PVC注射、PU发泡及各类注射成型模具中。2.2.2电铸成型技术电铸成型技术的原理同电镀一样,是依样模(现成制品或按制品图纸制成的母模)为基准(阴极),置放在电铸液中(阳极),使电铸液中的金属离子还原后一层一层地沉积在样模上,形成金属壳体,将其剥离后,与样模接触的表面即为模具的型腔内表面。该技术主要特点是节省材料、模具制造周期短,电铸层硬度可达40HRC,提高了耐磨性和寿命,粗糙度、尺寸精度与样模完全一致,适用于注射、吸塑、吹塑、搪塑、胶木模、玻璃模、压铸模等模具型腔及电火花成型电极的制造。2.2.3型腔表面精细花纹成型的蚀刻技术蚀刻技术是光学、化学、机加工综合应用的一种技术,它的基本原理是先把花纹图案制成胶片,再把胶片上的花纹图案复制在已涂上光敏材料的模具型腔表面上,经过化学处理,模具型腔表面形成不被蚀刻部分的保护层,再根据模具材质,选择相应蚀刻工艺,将花纹图案蚀刻在模具内表面上。该技术的主要特点是时间短、费用低,修补破损花纹图案可做到天衣无缝。2.3浇铸成型制模技术浇铸成型制模技术的共同特点是依样件为基准,浇铸出凸、凹模,型腔表面不需要机械加工。实际制模中主要有以下几种类型。2.3.1铋锡合金制模技术铋锡合金快速制模技术是经样件为基准,以Bi-Sn(铋锡)二元共晶合金(熔点138,胀缩率万分之三)为材料,有精密铸造的方法同时铸出凸模、凹模、压边圈的一种技术。该技术的特点是制模成本低,合金可重复使用,制造周期短,尺寸精度高,形状、尺寸与样件完全相符,一次铸模寿命可达500-3000件,非常适合新产品开发、工艺验证、样品试制及中小批量和平。2.3.2锌基合金制模技术这是一种以样件(或样模)为基准,以熔点为380左右的锌基合金为材料,分别浇注凸、凹模,原则上型腔表面不进行机械加工的一种制模技术。该技术特点是制模成本低、周期短,适用于制作薄板大型拉伸模、冲裁模及塑料模。2.3.3树脂复合成型模具技术这是一种以样模(或工艺模型)为基准,以树脂或其复合材料为流体材料,先浇注出凸(凹)模,再依据凸(凹)模贴上蜡片(间隙层),浇注凸(凹)模。该技术成型的型腔表面不需机械加工。该技术与CAD/CAM相结合,特点是模具尺寸精度高、制造周期短、成本低,是新产品试制、小批量生产工艺装备的新途径。适用于制作大型覆盖件拉伸模(也可局部镶钢)、真空吸塑、聚氨酯发泡成型模、陶瓷模、仿型靠模、铸造模等。2.3.4硅橡胶制模技术该技术以制件原型或模型为基准,将柔态硅橡胶制做成块,再靠高压力与模型完全吻合。2.4挤压成型技术2.4.1冷挤压成型利用铍铜合金的良好的导热性和稳定性,经固熔时效处理后,采用冷挤压制造模具凹模型腔。其特点是制造周期短,型腔精度高(IT7级),表面粗糙度Ra=0.025m,强度高,寿命可达50万次,无环境污染。2.4.2超塑成型制模技术该技术是利用金属材料在细化晶粒、一定成型温度、低变形速率条件下,材料具有最佳超塑性时,将事先制作好的凸模,用较小的力便可挤压出凹模的一种快速经济制模技术。超塑成型材料的典型代表是Zn-22%AL。2.5无模多点成形技术无模多点快速成形技术是以CAD/CAM/CAT技术为主要手段,利用计算机控制高度可调基本体群形成上下成形面,代替传统模具对板料进行三维曲面成形的又一现代先进制造技术。此项技术可以随意改变变形路径与受力状态,提高材料的成形极限,可反复成形,以此消除材料内部的残余应力,实现无回弹成形。2.6凯维朗(KEVRON)钢带冲裁落料制模技术新型钢带冲裁落料制模技术是一种不同于一般具有凸、凹模结构的钢带模,它是由单刃钢带与特制垫板组成的新型快速经济制模技术。这种模具重量轻,一般只有200kg,加工精度为0.35-0.50mm,可适合各种黑色和有色金属的0.5-0.65mm厚的板料加工。寿命可达到5-25万次,制造成本低。2.7模具毛坯的快速制造技术实型铸造由于大量的模具是属于单件或小批量生产,模具毛坯的制造质量和周期及成本对最终的模具质量和周期及成本的影响是至关重要的。现代模具毛坯已广泛地采用子实型铸造技术,所谓实型铸造就是利用泡沫塑料(聚苯乙烯PS或聚甲基丙烯酸酯PMMA)制作代替传统的木模或金属模,造型后不需取出模型,便可以浇铸,泡沫塑料模型的高温液体金属作用下,迅速燃烧气化而消失,金属液取代原来泡沫塑料模型所占有的位置,冷凝后形成铸件。实型铸造在实际应用中有下列几种情况。2.7.1干砂实型铸造即用55-100目的全干没有任何粘结剂的石英砂造型,用EPS或PMMA泡沫塑料制作的模型涂挂0.2-1mm厚透气性良好的耐火涂料层,以提高铸件表面光洁度,防止粘砂或塌箱。2.7.2负压实型铸造负压实型铸造又称V法造型。该技术是使用全干而无粘结剂的石英砂做型砂,用EPS或PMMA泡沫塑料做模型,在塑料薄膜的密封条件下,让整个铸型在负压条件下(真空度0.4-0.67MPa)进行液体金属浇铸,铸件凝固后解除负压即可得到表面光洁的铸件。2.7.3树脂砂实型铸造利用树脂砂做型砂,用EPS或PMMA泡沫塑料做模型,在常温、常压下进行液体金属浇铸而制取铸件。利用实型铸造的技术制造模具毛坯具有尺寸精度高(ISO9级),加工余量小(一般在5mm左右),不需要拔模斜度,不需要制型芯与泥芯撑,节省金属材料,节省做木模型的木材,制造周期短,成本低。该技术适合大型、复杂、单件模具毛坯的生产。陶瓷型精铸、失蜡精铸等技术在提高模具毛坯精度、降低加工工时、缩短制造周期、降低成本等方面也显示出其特有的优越性。2.8其它方面技术为了简化模具的结构设计,降低模具成本,缩短模具制造周期,在国内外也先后出现了一些其它方面新技术的应用,如快换模架、冲压单元、刃口堆焊、镶块铸造、氮气弹簧等。2.8.1氮气弹簧在模具上的应用氮气弹簧是一种新型弹性功能部件,用它代替弹簧、橡胶、聚氨酯或者气垫,它能够准确地提供压边力,在较小空间便可产生较大初始弹压力,不需预紧,在模具整个工作过程中弹压力基本恒定。弹压力大小及受力点位置可随时、准确、方便地调整,简化模具拉伸、压边、卸料等结构,简化模具设计,缩短制模周期,调试模具方便,缩短更换模具时间,提高生产效率。2.8.2快速换模技术由于产品品种的增多,使模具在生产中更换变得十分频繁,于是如何缩短冲压设备的停机时间,提高生产效率,快速换模技术受到了人们的关注。目前发达工业国家的一些大公司换模速度达到了惊人的程度,是否具有快速换模技术已成为企业技术进步的一项标志。总的趋势就是减少模具在设备上安装、固定、调整的时间,这既要在设备结构设计上予以考虑,又要在模具的结构设计、标准化方面予以考虑,将机上的作业尽可能地放在机下做。2.8.3冲压单元组合技术冲压单元组合技术是将常规的冲模分解为一个个简单的单元冲模,根据工序件的要求,排列组合,在同一次冲程内完成多种冲压工序的新型工艺装备,工作时冲压单元不与冲床滑块联接,只需滑块打击即可完成冲压工作。单独使用时它就是1副完整模具。它可以用来加工板料或型材的冲孔、落料、切角、切槽、切断及浅拉伸等。具有组装快捷、使用方便、通用性强、经济性好等特点,特别适合多品种、中小批量生产。2.8.4刃口堆焊技术在冲模制造中,以普通灰铸铁为基体,在刃口部位堆焊高硬度的合金钢,以代替模具钢镶块,这一技术成为世界先进工艺之一。这是一项节省制造工时,节省昂贵的模具钢材,缩短模具制造周期的快速经济制模技术。目前熔化极氩弧焊技术的应用,大大地提高了刃口堆焊的速度和质量。这项技术世界各国模具行业已广泛采用,取得了良好的经济效益。2.8.5实型铸造冲模刃口镶块技术这是一种用实型铸造的工艺方法制造冲模刃口的方法,即用合金钢铸件镶块代替锻造合金钢镶块。目前由于铸造工艺和热处理工艺不断完善和提高,铸造镶块的内在质量有了保证,故其应用范围在不断扩大。这项以铸代锻的新技术的突出特点是节省贵重模具钢材,简化模具制造工序,由于加工余量小,节省了大量机加工工时,缩短模具制造周期,降低模具成本。2.8.6可加工塑料在模具制造中的应用可加工塑料在发达的工业国家应用较普遍,特别是在汽车、飞机等制造业中,主要代替木材或金属制作汽车车身主模型、靠模、检具和铸造模型等。可加工塑料的主要特点是兼备木材和金属的优良加工性能,制作工艺简捷(可采用模塑、浇注、拼粘、雕塑等方法)、尺寸稳定性好、不变形、耐潮湿、耐腐蚀、易修复、易改型、重量轻、制作周期短、成本低。3结束语快速经济制模技术种类很多,其所具有的特点、应用范围各不相同,本文仅能概括地做一些简单介绍,每种技术在具体应用和实施过程中尚有许多具体的工艺过程、工艺参数及其技术特性。模具是基础工业之一,在全球化市场经济和各种高新技术的迅猛发展形势下,快速经济模具赋予了新的使命和全新的内涵,分类不断增加,快速经济制模材料向着多品种系列化迈进,工艺不断有新的创新和突破,与之配套设备相继问世,服务领域在不断地拓宽,创造的经济效益越来越显著。随着商品经济的发展,激烈的市场竞争,产品更新换代的加速,对快速经济制模技术在缩短周期、降低成本,提高精度和延长寿命方面的要求势必会越来越高。由于它能使企业赢得市场,创造显著的经济效益,越来越受到企业家的青睐和有关领导部门的极大关注与政策资金的支持。各种快速经济制模技术在推广应用过程中也会不断完善成熟和发展,由于高新技术的发展,各种技术的复合与渗透,为适应生产中的不同需求,今后必定会形成一些新型、节约能源、节约材料的快速制模技术。The technology of Microlens array injection moldingAbstract 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 16.05.05.026.05.010.0356.06.09.05.010.015.05.065.05.0712.05.05.04 Results 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.4.1 Surface 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).(a)Injection molded microlensarrays (PMMA) (b) Injectionmolded microlenses of 300 mdiameter for different materialsFig. 3. SEM images of theinjection molded microlensarrays and microlensesAs 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 (%)1234567PS200300500-7.625.862.38-7.592.03-0.382.082.860.51-5.565.611.47-8.6660161.47-11.444.291.47-9.475.731.95PMMA2003005007.205.77-0.661.315.60-1.62-3.886.453.98-5.805.952.80-0.975.95-0.72-8.536.68-0.904.86-2.62-0.72PC20030050023.026.20-0.9316.054.965.0916.872.66-1.8619.664.531.8833.974.786.9618.671.792.43-2.944.15-1.55It 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).Surfce 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 300m). a effect of packing pressure, b effect of flow rate,c effect of packing time4.2 Surface 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.a Nickel mold insert, b PS, c PMMA, d PCFig. 6. AFM images and averaged surface roughness, Ra, values of the mold insert and injection molded 300 m diameter microlenses.4.3 Focal 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 ¥) 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.5 ConclusionThe 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.Modern mold technologyIntroductionAlong with the global economy development, the new technological revolution made the new progress and the breakthrough unceasingly, the technical leap development already becomes the important attribute which the impetus world economics grew. The market economy unceasing development, urges the industry product more and more to the multi- varieties, high grade, the low cost direction to develop, in order to maintain and strengthens the product in market competitive power, product development cycle, production cycle more and more short, thereupon to makes each kind of product the essential craft equipment mold request to be more and more harsh. On the one hand the enterprise for the pursue scale benefit, causes the mold to turn towards high speed, is precise, the long life direction develops; On the other hand enterprise in order to satisfy the multi- varieties, the product renewal quickly, wins the market the need, requests the mold to turn towards the manufacture cycle to be short, the cost low fast economy direction develops. The computer, the laser, electronic, the new material, the new technical development, causes the fast economical pattern making technology even more powerful, the application scope expands unceasingly, the type increases unceasingly, the creation economic efficiency and the social efficiency are more and more remarkable. 1.Injection mold designThe injection molding application temperature dependence change material performance, through uses the mold to obtain the final shape separate part to complete or to complete the size close. In this kind of process of manufacture, the liquid material is compelled to fill, coagulates in the die space mold. first, must create a pattern mold to need a design model and carries the box. First, must create a pattern mold to need a design model and carries the box. The design model has represented the end product, but carries the box to represent the mold modules bulk volume. The injection mold design involves the mold structure and the function constituent widespread experience knowledge (heuristic knowledge). In the typical process molds the recent development to be possible to divide into four big stages: Product design, molds ability appraisal, part detailed design, insertion die space design and detailed mold design. in the initial stage, the product concept is in (usually is together a combination marketing and project) completes by several people. The initial stage main focal point is analyzes the market the opportunity and the adaptation strategy. In the first stage, the canonical correlation craft manufacture information is increased to the design, designs the geometry detail. The conceptual design use suitable manufacture information transforms as the goods which may make. In the second stage, the drawing of patterns direction and a minute hairs breadth buy for use examine molds ability. Otherwise, the components shape revises once more. In the third stage, the components geometry is uses for to establish the mold the core and the die space shape, the mold the core and the die space, will use for to form the components. Generally, the contraction and the expansion need to perform to consider, like this, in processes under the temperature, the formation will have the correct size and the shape. Th
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