電流線圈架塑料注塑模具設計【線圈骨架】【說明書+CAD】,線圈骨架,說明書+CAD,電流線圈架塑料注塑模具設計【線圈骨架】【說明書+CAD】,電流,線圈,塑料,注塑,模具設計,骨架,說明書,仿單,cad 學校名稱 畢業(yè)設計說明書 課題: 電 流 線 圈 架 塑 料 模 設 計 系 別 機械工程系 班 級 姓 名 學 號 指導老師 年 月 日 目錄 一． 緒 論………………………………………3-8 二．計算設計與說明……………………………9-17 三．參考文獻……………………………………18 四．總結…………………………………………19 第一章 緒 論 塑料模具是利用其特定形狀去成型具有一定形狀和尺寸的塑料制品的工具。塑料模具對塑料制品的質(zhì)量和操作難易程度都有相當?shù)挠绊懸虼艘竽＞咴谏a(chǎn)度，外觀，物理性能等各方面都滿足使用要求并要求其效率高，操作簡便，結構合理，制造容易，成本低廉。現(xiàn)代塑料制品中合理的加工工藝，高效的設備，先進的模具是必不可少三項重要因素。尤其是塑料模具要實現(xiàn)塑料加工工藝要求，制件使用要求和造型設計起著十分重要的作用。因此，對塑料模具生產(chǎn)也提出了越來越高的要求。因此促使模具生產(chǎn)不斷向前發(fā)展。 模具工業(yè)是現(xiàn)代工業(yè)的基礎，它的技術水平很大程度上決定了產(chǎn)品的質(zhì)量和市場的競爭能力。隨著我國加入“WTO”步伐的日益加快?！叭胧馈睂ξ覈＞吖I(yè)產(chǎn)生重大而深遠的影響，經(jīng)濟全球化的趨勢日益明顯，同時世界眾多知名公司不斷進行構調(diào)整，國內(nèi)市場的國際性進一步現(xiàn)，該行業(yè)將經(jīng)受更大的沖擊，競爭也會更加激烈。在如此嚴峻的行業(yè)背景下，我國的技術人員經(jīng)過不斷的改革和創(chuàng)新使得我國模具水平有了較大的提高，大型，復雜，精密，高效和長壽命模具有上了新的臺階。 塑料制品的成型是塑料成為具有實用價值制品的重要環(huán)節(jié)。塑料成型方法已達40多種。其中最重要的是注射，擠出，吹塑和壓制等。它們幾乎占了整個塑料成型的85%；其中注射尤為突出，占塑料成型的30%以上。注射模具成形是熱塑性塑料成型的一種方法，幾乎所有的熱塑性塑料都可以用此方法成型，有些熱固性塑料也可以用注射模塑成型。 我國塑料模的發(fā)展，極其迅速?，F(xiàn)已具有相當規(guī)模。無論是設計水平，加工制造技術，還是CAD技術都有了明顯的提高。 隨著政府和企業(yè)界對模具工業(yè)的重視程度的不斷提高，模具的發(fā)展速度在不斷加快，技術得到進一步發(fā)展，模具工業(yè)的發(fā)展前景十分的廣闊。 第二章 塑料?，F(xiàn)狀 近年來我國塑料模具有了長足的進步，大型，復雜，高效和長壽命模具又上了新臺階，特別體現(xiàn)在高科技應用的深度和廣度上，表現(xiàn)在下列幾個方面： （1）廣泛應用CAD/CAM/CAE，特別是加工方面，計算機造型，編程并由數(shù)控機床加工已是主要手段，CAE軟件也已得到廣泛應用，提高了設計水平。 （2）熱流道技術的推廣應用更上一層樓，內(nèi)熱式和外熱式流道裝置，自制熱噴咀和引進熱噴咀都得到了應用，有的已達到國際先進水平。 （3）氣體輔助注射技術已得到應用，不少廠家均采用了此技術，例如熊貓公司開發(fā)氣輔模具是時，采用了C -MOLD氣輔分析軟件使模具順利研制成功。 （4）應用優(yōu)質(zhì)塑料模具鋼，現(xiàn)注射模較少采用45鋼，P20鋼得到廣泛應用，大大提高了使用壽命和表面光潔度。 （5）抽芯脫模機構的創(chuàng)新設計，很多廠家已設計出結構新穎，脫模容易，具有創(chuàng)新意識的脫模機構，并解決了很多以前脫模難的問題但與發(fā)達國家。 （6）精密，復雜，大型，高壽命模具的制造水平有了很大提高。那些尺寸精度高，模具零件要求互換，塑件形狀復雜的模具由于采用了CAD三維技術計算機模擬注射成型，氣輔技術等先進的方式，使模具達到了國外同類模具水平。模具的壽命也達到100萬次或更高。 我國的模具工業(yè)在“九五”期間雖有較快發(fā)展，但相比一些發(fā)展較快的國家，我國仍存在相當大的差距。據(jù)資料顯示，CAD，CAE的應用，發(fā)達國家遠高于中國，而中國大陸的應用程度有遠低于香港，臺灣。特別是FLOW軟件和COOL軟件，發(fā)達國家已普及而中國大陸才剛剛起步。差距之大，使人感慨。在模具標準零件及標準模架方面，發(fā)達國家已普及，并實現(xiàn)了商品化，而中國大陸已有國家標準但尚未實現(xiàn)商品化。熱流道及熱管技術發(fā)達國家已大量使用，并形成了系列和標準。而我國大陸70年代開始研究迄今尚無標準。 在發(fā)達國家及發(fā)達地區(qū)塑料模具行業(yè)向小而專的方向發(fā)展；向技術密集方向發(fā)展；高技術與高技藝相結合；生產(chǎn)規(guī)模以小而專見長；專業(yè)化與柔性化相結合。而在中國大陸則恰恰相反。獨立的模具工廠難以生存；多屬于勞動密集型企業(yè)；有忽視高技藝的傾向；大而全居多；尚無專業(yè)化與柔性化相結合的規(guī)劃。而且大型，精密，復雜，長壽命模具產(chǎn)需矛盾仍然十分突出，高檔模具進口的比例達40%以上，而有些模具已出現(xiàn)過剩。 第三章 模具產(chǎn)品發(fā)展趨勢 模具工業(yè)是我國國民經(jīng)濟的基礎工業(yè)，隨著全球經(jīng)濟的發(fā)展，新的技命不斷取得新的進展和突破，市場經(jīng)濟的不斷發(fā)展，促使工業(yè)產(chǎn)品越來越向多品種，小批量，高質(zhì)量，低成本的方向發(fā)展，于是對制造各種產(chǎn)品的關鍵工藝裝備-模具的要求越來越苛刻，模具必然會有如下發(fā)展趨勢： 1. 模具CAD/CAM/CAE技術將日益深入人心并發(fā)揮越來越重要的作用?；诰W(wǎng)絡的一體化系統(tǒng)結構CAD/CAM/CAE將達到開放性，兼容性和專業(yè)化的統(tǒng)一。CAD/CAM軟件在智能化，面向對象，基于特征和面向制造方面將獲得長足的進步。模具3D分析的重要性更加明確。國產(chǎn)軟件CAXA系統(tǒng)，HSC系統(tǒng)和Z-MOLO等軟件的功能和水平將不斷提高和完善。 2. 模具的精度將越來越高，并日趨大型化，現(xiàn)在模具精度已達2—3毫米，不久1毫米精度的模具將上市。隨著零件微化及精度要求的不斷提高，這就要求發(fā)展超精加工。另一方面，由于用模具成型的零件日益大型化以及由于高效率要求而發(fā)展的一模多腔，勢必要求模具隨之大型化。 3. 隨著熱流道技術的日益推廣應用，熱流道模具在塑料模具中的比重將逐步提高，由于熱流道技術的模具可提高制件的生產(chǎn)率和質(zhì)量，并能大幅度節(jié)約制件的原材料，因此，熱流 道技術的應用將會發(fā)展很快，比例也將逐漸提高。 4. 隨著塑料成型工藝的不斷改進與發(fā)展，氣輔模具及適應高壓注射成型等工藝的模具也將隨之發(fā)展。氣體輔助注射成型技術能改善塑件的內(nèi)在和外觀質(zhì)量。具有注射壓力低，制品變形小，節(jié)約原料，提高制件生產(chǎn)率，從而大幅度降低成本等優(yōu)點。而高壓注射成型可減小樹脂收縮率，增大塑件尺寸的穩(wěn)定性，提高其精度。 5. 快速經(jīng)濟制模技術的前景十分廣闊，突出的表現(xiàn)在快速成型（RP）快速模具制造（RT）上。21世紀，這種生產(chǎn)方式占工業(yè)生產(chǎn)的比例將達75%以上。模具的生產(chǎn)周期將越來越短，成本也將相應降低。精度和壽命又能滿足生產(chǎn)上的使用要求RP+RT的研究成為國內(nèi)外RPM界十分關注并大力發(fā)生的領域之一，正大力向著快速模具制造（RTM）發(fā)展，一些新的快速成型方法相繼涌現(xiàn)，RPM是電腦，激光，光學掃描，先進的新型材料，計算機輔助設計（CAD），計算機輔助加工（CAM），數(shù)控（CNC）綜合應用的高進技術。利用它可以直接或間接的快速制模?？焖僦颇＜夹g為適應市場的需求，必然呈現(xiàn)多元化的發(fā)展趨勢。 6. 模具標準件的應用將日益廣泛。模具標準件不但能縮短模具制模周期，而且能提高模具質(zhì)量和降低模具制造成本，因此模具標準件的應用必將日益廣泛，在今后的模具市場中必將成為一類。十分活躍而又高速發(fā)展的產(chǎn)品。 7. 三維掃描儀的多樣化和高速化將會使模具的逆向工程獲得發(fā)展，逆向工程技術已成為模具制造，信息傳遞的簡便途徑，是模具CAD/CAM的關鍵技術之一。 8. 高性能的模具鋼的用量也將以較快速度增長，由于對模具鋼的要求越來越高，迫切需要研制出高強度，高硬度，高耐磨性愜意加工，熱處理變形小，導熱性優(yōu)良的制模材料，并廣泛的投入應用。如各種導型材模具，PVC塑料等。 9. 隨著以塑料鋼的進一步發(fā)展，塑料模的比例將不斷提高，發(fā)展速度也將高于沖模。對模具的要求也將越來月高，高檔模具在市場上的份額也將逐步擴大。 第四章 計算設計與說明 一：材料分析 如前圖所示塑料制件，名稱為電流線圈架零件圖，材料ABS塑料 比重:1.05克/立方厘米 成型收縮率:0.4-0.7% 成型溫度：200-240℃ 干燥條件：80-90℃ 2小時 特點： 1、綜合性能較好,沖擊強度較高,化學穩(wěn)定性,電性能良好. 2、與372有機玻璃的熔接性良好,制成雙色塑件,且可表面鍍鉻,噴漆處理. 3、有高抗沖、高耐熱、阻燃、增強、透明等級別。 4、流動性比HIPS差一點，比PMMA、PC等好，柔韌性好。 用途：適于制作一般機械零件,減磨耐磨零件,傳動零件和電訊零件. 成型特性： 1.無定形料,流動性中等,吸濕大,必須充分干燥,表面要求光澤的塑件須長時間預熱干燥80-90度,3小時。 2.宜取高料溫,高模溫,但料溫過高易分解(分解溫度為>270度).對精度較高的塑件,模溫宜取50-60度,對高光澤.耐熱塑件,模溫宜取60-80度。 3、如需解決夾水紋，需提高材料的流動性，采取高料溫、高模溫，或者改變?nèi)胨坏确椒ā? 4、如成形耐熱級或阻燃級材料，生產(chǎn)3-7天后模具表面會殘存塑料分解物，導致模具表面發(fā)亮，需對模具及時進行清理，同時模具表面需增加排氣位置。 一．工藝性分析 （1） 該塑件尺寸中等，一般精度等級IT=4為方便成型，方便開發(fā)模具，采用一模也腔，如需要可對制品進行后加工。 （2） 該制件采用點交口形式，方便成型。 （3） 為方便加工和熱處理，型腔和型芯采用部分拼鑲結構。 制件要求： （1） 制件表面光滑平整，不準有飛邊、毛刺、及其它的外觀缺陷。 （2） 色澤均勻協(xié)調(diào)，不準有氣泡，裂紋縮孔等缺陷。 （3） 制件尺寸要求在偏差范圍內(nèi)，并達到所需要的精度。 二．計算工件體積 V底≈2504.45 V凸≈2037 V圓弧≈830.16 V總≈V底+ V凸+ V圓弧≈5.37cm 查表6-1（參考文獻1）塑料ABS的密度為1.02～1.05g/cm 單件塑件的重量MS ≈5.37X1.05≈6g 三．型腔.型芯工作部位尺寸的確定 1.平均收縮率計算型腔徑向尺寸 ABS的塑件收縮率是0.4～0.7%平均收縮率S=（0.4%+0.7%）/2=0.55% 型腔工作部位尺寸： 型腔徑向尺寸: Lm 1 =[(1+S)Ls-X△]+δ 0=[65X（1+0.55%）-0.75X0.32]0.1 0=65.12+0.1 0 Lm 2=[(1+S)Ls-X△]+δ 0=[34X（1+0.55%）-0.75X0.26] +0.86 0=34.122+0.86 0 2. 平均收縮率計算型腔深度、型芯高度尺寸 型腔深度尺寸: Hm =[(1+s)Hs-X△]+δ 0=[12X（1+0.55%）-0.75X0.18]+0.06 0=11.93+0..6 0 型芯徑向尺寸: lm =[(1+s)ls+X△]根據(jù)上式分別得到型心徑向尺寸為： lm1=[(1+0.55%)x13.5+0.75x0.18]=14.920 -0.06 lm2=[(1+0.55%)x10.5+0.75x0.18]=11.910 -0.06 lm3=[(1+0.55%)x15+0.75x0.2]=15.230 -0.15 型芯高度尺寸:hm 1 =[(1+s)hs+X△]0 –δ= [12X（1+0.55%）+0.75X0.2]0 -0.06=12.760 -0.06 hm 2 =[(1+s)hs+X△]0 –δ=[（1+0.55%）X4.5+0.75X0.14]0 -0.04=4.540 -0.04 X—修正系數(shù)取0.5 △—塑件公差（mm） δ—模具制造公差，取1/3△ 四.澆注系統(tǒng)的設計 （1） 確定分型面位置，該塑件的結構如圖 該件結構比較簡單分型面如上圖 （2）確定澆口形式及位置，為了提高成型效率，采用點澆口形式，選在制件底部中心位置。并采用雙分型面塑模結構，澆口在第一次分型時被拉斷。 澆口直徑可以根據(jù)經(jīng)驗公式計算d=（0.14～0.20） 式中d—澆口直徑（mm），S—在澆口處的避厚(mm)， A—型腔表面積 d─(0.14～0.20) （澆口直徑也可以根據(jù)經(jīng)驗值取1 mm), 澆口錐角取β=15o， 澆口傾斜角取〆=45o 五 選用模架 （1）可看出型腔為整體式，因此型腔的強度和剛度按型腔為整體式進行計算。由于型腔壁厚計算比較麻煩也可參考經(jīng)驗推薦數(shù)據(jù)查<<模具設計指導>>表6─15型腔側壁的S=9mm （2）初選注射機 1) 注射量：該塑料件單件重6克，澆注系統(tǒng)為點澆口，粗略估算M澆 ≈1g 總體積V 塑件≈6.37cm 總質(zhì)量M=6+1g≈7g 滿足注射量 V 機 ≥V 塑件/0.8 式中V 機－額定注射量（cm） V 塑件 －塑件與澆注系統(tǒng)凝料體積和（cm） V 塑件/0.8=6.37/0.8=7.96cm 2）注射壓力: P 注≥P 成型 查表6—5(參考文獻一)ABS塑料成型時的注射壓力P 成型 =70～90MPa 3）鎖模力：P 鎖模力≥PF 式中P—塑料成型時型腔壓力，ABS塑料的型腔壓力P=30MPa F—澆注系統(tǒng)和塑件在分型面上的投影面積和， F=17X14X2 =476mm PF=30×476N=14.28KN 根據(jù)以上分析（計算）查表6—24(參考文獻一)初選注射機型號為：Xs-Z-30 注射機Xs-Z-30有關技術參數(shù)如下: 最大開合模行程S 160mm 模具最大厚度 180 mm 模具最小厚度 60mm 噴嘴孔直徑 2mm 動，定模板尺寸 250×280mm 拉桿空間 235mm 噴嘴圓弧半徑 12mm (4) 選標準模架 根據(jù)以上分析，計算機以及型腔尺寸及位置尺寸確定模架的結構形式和規(guī)格，查表7—1，7—3選用 A 4-200160-02-Z2 GB/T 12556.1-1990 定模板厚度： A=16mm 動模板厚度： B=25mm 墊塊厚度： C=50mm 模具厚度： H 模=88+A+B+C=（88+16+25+50）=179mm 模具外型尺寸： 200mm×160mm×179mm 六.校核注射機 （1）注射量，鎖模力，注射壓力, 模具厚度的校核。由于在初選注射機和選用標準模架時是根據(jù)以上四個技術參數(shù)及計算壁厚等因素選用的，所以注射量，鎖模力,注射壓力,模具厚度不必進行校核已符合所選注射機要求。 （2）開模行程的校核 注射機最大開模行程因按與模厚有關時來校核,雙分型面注射模可按下式校核 注射機的最大開模行程S S≥2h件+h澆+（5～10）才滿足要求 式中 h件-塑料制品的高度 h澆-澆注系統(tǒng)的高度 2h件+h澆+（5～10）≈74mm 因為S為160mm,所以S≥74mm 滿足要求 （3）模具在注射機上的安裝：從標準模架外型尺寸看小于注射機的拉桿空間，并采用壓板固定模具，所以注射機的規(guī)格滿足要求。 七 模具導向機構的設計 導向機構對塑料模具是不可缺少的部件，因為模具在閉合時要求有一定的方向和位置，所以必須設有導向機構，導柱安裝在動模一邊還是定模一邊均可，通常導柱設在主型心周圍，導向機構主要有定位 、導向、承受一定 側壓力三個作用。 本模具是一模一具的模具，一般采用四根導柱的導向機構。 1. 導柱機構的技術要求 （1） 長度 導柱導向部分的長度應該比凸摸端面的高度高出8-12mm，以免出現(xiàn)導柱未導正方向而型心先進入型腔的情況 （2） 形狀 導住前端應該做成錐臺形或半球形以使導柱能順利地進入導向孔，本模具導柱前端采用錐臺形。 （3） 材料 一般采用20鋼或者t8，t10鋼硬度50-55 HRC （4） 數(shù)量及布置 導柱應該合理均勻分布在模具分型面的四周 （5） 配合精度 導柱的導向部分通常采用H7/57或H8/57的間隙配合 2導套的結構和技術要求 （1） 形狀 為使導柱順利進入導套，導套的前端面倒圓角，導向孔最好作成通孔，以利于排出孔內(nèi)的空氣，如果摸板較厚，導孔必須作成盲孔時可在盲孔的側面打一個小孔排氣或在導柱的側壁磨出排氣槽 （2） 材料 可采用與導柱相同的材料 （3） 配合精度 直導套用H7/r6過盈配合潛入摸板 （4） 導柱與導套的配用 由模具的結構及生產(chǎn)要求而定 八 定模座板 動模座板的設計 定模座板 使定模固定在注射機的固定工作臺面是的模具 動模座板 使動模固定在注射機的移動工作臺面是的模具 （1） 選用的摸板在注射機上的安裝只需在定模板上的設置定位孔 （2） 動，定模座板的厚度 一般采用Q235或45鋼材料為了把模具固定在注射機上，動定模座板的兩側均需要比動定摸板的外型尺寸加厚25-30mm 九.推出結構設計 1 確定頂出方式和頂桿位置 根據(jù)制品結構特點,確定在制品的兩側設置四根普通的圓頂桿，普通的圓形頂桿按GB4169.1-1984選用，均可滿足頂桿剛度要求。 查表7-13,選用Ф4mmx100mm型號的圓形頂桿4根.由于件較小,推出裝置可不設導向裝置 推件力的計算 推件力F=AP（μcosα-sinα）+qA1 式中 A——塑件包絡型芯的面積 p——塑件對型芯單位面積上的包緊力，取0.8X10-1.2X10Pa α——脫模斜度 q——大氣壓力0.09M Pa μ——塑件對鋼的摩擦系數(shù)μ，約為0.1-0.3 F≈1660N 十 水冷系統(tǒng)的設計 冷卻水孔開設原則 （1） 冷卻水孔的數(shù)量應盡可能多，直徑盡量大。 （2） 各冷卻水孔至型腔表面的距離應相等，一般保持在15—20毫米范圍內(nèi)，距離太近不易冷卻均勻，太遠則效率底，水孔直徑一般取Ф8—12毫米，孔距最好為水孔直徑的5倍。 （3） 水孔通過壤塊時，防止壤套等漏水。 （4） 冷卻管路一般不宜設在型腔內(nèi)塑料容接的地方，以免影響塑件強度。 （5） 水管接頭（冷卻水嘴）應設在不影響操作的一側 本模具型腔和型芯冷卻形式采用循環(huán)式，因為圓孔循環(huán)或矩形槽循環(huán)冷卻，對型腔，型芯的冷卻效果好。 十一 排氣系統(tǒng)的設計 由于制件尺寸較小,利用分型面和推桿的配合間隙排氣即可. 參 考 文 獻 一．《模具設計指導》 史鐵梁 主編 機械工業(yè)出版社 二．《塑料成型工藝與模具設計》 屈華昌 主編 高等教育出版社 三．《模具設計與制造簡明手冊》 馮炳堯、韓泰英等主編 上海科學技術出版社 設 計 總 結 Microsystem Technologies 10 (2004) 531–535 _ Springer-Verlag 2004 DOI 10.1007/s00542-004-0387-2 Replication of microlens arrays by injection molding B.-K. Lee, D. S. Kim, T. H. Kwon B.-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, Korea e-mail: thkwon@postech.ac.kr Abstract 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 fabrication Microlens 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 500μm -(a 2 × 2 array), 300μm -(2 × 2) and 200μm (5 × 5) diameter arrays, and their heights were 20.81, 17.21 and 8.06 μm, 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 μm diameter microlens array (c) SEM image of 300 μmdiameter microlens array 3 Injection molding experiments A 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 experiment The 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 experiments Case Flow rate (cc/sec) Packing time (sec) Packing pressure(MPa) 1 12.0 5.0 10.0 2 12.0 5.0 15.0 3 12.0 5.0 20.0 PS 4 12.0 2.0 10.0 5 12.0 10.0 10.0 6 18.0 5.0 10.0 7 24.0 5.0 10.0 PMMA 1 6.0 10.0 10.0 2 6.0 10.0 15.0 3 6.0 10.0 20.0 4 6.0 5.0 10.0 5 6 7 6.0 9.0 12.0 15.0 10.0 10.0 10.0 10.0 10.0 PC 1 6.0 5.0 5.0 2 6.0 5.0 10.0 3 5 6.0 6.0 9.0 5.0 10.0 15.0 5.0 6 5.0 5.0 7 12.0 5.0 5.0 4 Results and discussion Before detailed discussion of the experimental results, it might be helpful to summarize why flow rate, packing pressure 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 when cooled down, so that enough material should flow into a mold cavity during this stage to control the dimensional accuracy. 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 optical quality. 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 profiles Figure 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 the injection molded microlens arrays and microlenses (a) Injection molded microlens arrays (PMMA) (b) Injection molded microlenses of 300 μmdiameter for different materials As 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 ( μm) Relative deviation (%) 1 2 3 4 5 6 7 PS 200 300 500 -7.62 5.86 2.38 -7.59 2.03 -0.38 2.08 2.86 0.51 - 5.61 1.47 -8.66 6016 1.47 -11.44 4.29 1.47 - 5.73 1.95 PMMA 200 300 500 7.20 5.77 -0.66 1.31 5.60 -1.62 -3.88 6.45 3.98 -5.80 5.95 2.80 -0.97 5.95 -0.72 -8.53 6.68 -0.90 4.86 -2.62 -0.72 PC 200 300 500 23.02 6.20 -0.93 16.05 4.96 5.09 16.87 2.66 -1.86 19.66 4.53 1.88 33.97 4.78 6.96 18.67 1.79 2.43 -2.94 4.15 -1.55 It 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 μm 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 μm 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 μm 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 flowing into the cavity. Therefore, the effect of packing time disappears after a certain time depending on the processing conditions. Fig.4a–c(leftside).Surface profiles of microlens (PC with diameter (/) of 300 μm). a effect of packing pressure, b effect of flow rate, c effectof packing time Fig.5a–c.(rightside)Surface profiles of microlens (PMMA with diameter(/) of 300 μm). a effect of packing pressure, b effect of flow rate,c effect of packing time 4.2 Surface roughness Averaged surface roughness, Ra, values of 300 μm 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 μm · 5 μm. 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 μm diameter microlenses. a Nickel mold insert, b PS, c PMMA, d PC 4.3 Focal length The 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 μm diameter microlens, 1.130 mm (with R1= 0.662 mm and R2=∞) for 300 μm microlens and 2.580 mm (with R1=1.512 mm and R2=∞) for 500 μm 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 Conclusion The 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. References 1. Ruther P; Gerlach B; Go¨ttert J; Ilie M; Mu¨ller A; O?mann C (1997) Fabrication and characterization of microlenses realized by a modified LIGA process. Pure Appl Opt 6: 643–653 2. Popovic ZD; Sprague RA; Neville Connell GA (1988) Technique for monolithic fabrication of microlens array. Appl Opt27: 1281–1284 3. Beinhorn F; Ihlemann J; Luther K; Troe J (1999) Micro-lens arrays generated by UV laser irradiation of doped PMMA. Appl Phys A68: 709–713 4. 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: 98–103 5. Ong NS; Koh YH; Fu YQ (2002) Microlens array produced using hot embossing process. Microelectron Eng 60: 365–379 6. Lee S-K; Lee K-C; Lee SS (2002) A simple method for microlens fabrication by the modified LIGA process. J Micromech Microeng 12: 334–340 7. 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: 523–531 8. Bauer W; Knitter R; Emde A; Bartelt G; Go¨hring D; Hansjosten E (2002) Replication techniques for ceramic microcomponents with high aspect ratio. Microsyst Technol 7: 85– 90 微透鏡陣列注塑成型的復制 B.-K. Lee, D. S. Kim, T. H. Kwon 樸航科技大學(POSTECH) 機械工程學院 San 31, Hyoja-Dong, Nam-Gu, Pohang, 790-784, Korea 電子郵箱l: thkwon@postech.ac.kr 摘要 微透鏡陣列注塑成型，可作為一種非常重要的大量生產(chǎn)技術。因此我們在近來的研究中非常關注， 為了進一步了解注塑成型在不同的加工條件下對可復制的微透鏡陣列剖面的影響，如流量、填料壓力和填料時間，對3種不同的高分子材料(PS，PMMA和PC)進行了大量的試驗。 鎳金屬模具嵌件微陣列就是利用改良的LIGA技術電鍍主裝配的顯微結構制造的。在表面輪廓得到測量的前提下，研究工藝條件對可復制的微透鏡陣列的影響。實驗結果表明， 填料壓力和流速對注射模塑的終產(chǎn)品的表面輪廓有重要的影響。 原子力顯微鏡測量表明， 微透鏡陣列注塑成型的平均表面粗糙度值小于模具嵌件成型， 并在實際運用中，能與精細的光學元件相媲美。 1 說明 微型光學產(chǎn)品，如微透鏡或微透鏡陣列已廣泛應用于光學數(shù)據(jù)存儲、生物醫(yī)學、顯示裝置等各個光學領域。微透鏡和微透鏡陣列不僅在實踐應用上，而且在微型光學的基礎研究上都是非常重要的。有幾種微透鏡或微透鏡陣列的制作方法，如改良的LIGA技術[1] ，光阻回流進程[2]，紫外激光照射[3]等。還有復制技術，如注塑模壓成型[4]和熱壓[5]技術 ，這種方法對于減少大規(guī)模生產(chǎn)的微型光學產(chǎn)品的成本尤為重要。由于其優(yōu)越的生產(chǎn)和再生產(chǎn)能力，只要注塑成型過程中能很好的復制微觀結構，那么肯定是最適合于降低大量生產(chǎn)成本的方法。 基于這點，檢查注塑成型能力并確定成型加工條件是注塑成型微觀結構過程中最重要的步驟。在本次研究中，我們考察了工藝條件對可復制的微透鏡陣列的注射成型的影響。微透鏡陣列是用之前介紹過[6，7]的改良的LIGA技術來編制的。注塑成型實驗采用的是一種鍍鎳金屬模具，來探討了幾種不同工藝條件對成型的影響。通過對微透鏡陣列的表面輪廓測量，用來分析工藝條件產(chǎn)生的影響。最后，利用原子力顯微鏡(AFM)測量微透鏡的表面粗糙度值的大小。 2 模具嵌件的制造 利用改良的LIGA技術[6]，在一個有機玻璃板上制造出具有幾種不同直徑微透鏡陣列。此種技術是先用X光照射有機玻璃板，然后再進行熱處理兩部分構成的。X-射線照射引起有機玻璃分子質(zhì)量的減少，同時降低了玻璃化轉變溫度，并因此導致凈含量的增加，在熱循環(huán)的作用下，微透鏡發(fā)生微膨脹[7]。利用[7]中提出的方法，結合改良的LIGA技術可以預測微透鏡形狀的變化過程。 在試驗中使用的微透鏡陣列，有500μm (2×2陣列)，300μm (2×2)和200μm (5×5)的直徑陣列，高分別是20.81μm，17.21μm和8.06μm。采用改良的LIGA技術制造微透鏡陣列作為一個主要的技術，用來制作鍍鎳的金屬模具的注塑成型。另一些特殊材料，因為它們的強度不夠或熱性能差而不能直接進行微細加工，當作模具或金屬模具使用，如硅、光阻劑或高分子材料。盡量使用具有良好機械性能和熱性能的金屬材料，因為它們能在可復型加工過程中經(jīng)受高壓力和不斷變化的溫度。因此，為了利用這種復制技術進行大批量生產(chǎn)，我們選擇使用金屬模具材料而不是有機玻璃硅晶體。一些特殊技術，如低壓注塑成型[8]技術，應該作為良好的復制加工方法被采納。 電鍍模具的最終大小為30 mm×30 mm×3mm。鍍鎳金屬模具所具有的微透鏡陣列如圖1所示。 圖1 鍍鎳模具嵌件的制造 （a）直接觀察；（b）直徑為200μm 的微透鏡陣列電子顯微鏡圖像；（c）直徑為300μm的微透鏡陣列電子顯微鏡圖像 3 注塑成型實驗 傳統(tǒng)注塑機(Allrounders 220 M，Arburg)多用做實驗機。注塑模具設計的模架就是利用一塊框形支撐板固定鍍鎳模具(如圖2所示)。