塑料蓋注射模具設計【電源盒】【一模四腔】【說明書+CAD】

塑料蓋注射模具設計【電源盒】【一模四腔】【說明書+CAD】,電源盒,一模四腔,說明書+CAD,塑料蓋注射模具設計【電源盒】【一模四腔】【說明書+CAD】,塑料蓋,注射,模具設計,電源,說明書,仿單,cad 湖南工學院（籌） 畢業(yè)設計（論文）任務書 題 目 塑料蓋注射模設計 起 止 時 間 2006年3月—2006年6月 學 生 姓 名 專 業(yè) 班 級 學 號 指 導 老 師 教研室主任 系 主 任 2006年5月27日 湖南工學院畢業(yè)設計 計 算 內 容 說 明 目 錄 一、塑件分析及注塑機選定————————————— 2-6 二、模具設計 1、主流道設計—————————————————— 7-8 2、定模設計 —————————————————— 8-11 3、支撐板設計——————————————————11-12 4、排溢系統(tǒng)設計——————————————————12 5、推出機構設計———————————————— 14-14 6、合模機構導向機構設計————————————15-16 7、內型腔設計計算——————————————— 16-22 8、推桿設計———————————————————— 22 9、溫控系統(tǒng)設計———————————————— 23-24 10、設計小結———————————————————— 25 11、參考資料 ——————————————————— 26 共 26 頁 第 1 頁 南工學院畢業(yè)設計 計 算 內 容 說 明 電源盒注射模設計 塑件圖如下 ： 該塑件選用塑料為ABS. ABS中文名：丙烯腈-丁二烯-苯乙烯共聚物 英文名：Acrylinitrile-Butadiene-Styrene。 基本特性： ABS是由丙烯腈、丁二烯、苯乙烯共聚而成的。這三種組分的各自特性，使ABS具有良好的綜合力學性能。丙烯腈使ABS有良好的耐腐蝕性及表面硬度，丁二烯使ABS堅韌，苯乙烯使它有良好的加工性和染色性能。 共 26 頁 第 2 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 ABS無毒、無味，呈微黃色，成型的塑件有較好的光澤，密度在1.02~1.05g/cm3,其收縮率為0.3~0.8%。ABS 吸濕性很強，成型前需要充分干燥，要求含水量小于0.3%。流動性一般，溢料間隙約在0.04mm。ABS有極好的抗沖擊強度，且在低溫下也不迅速下降。有良好的機械強度和一定的耐磨性、耐寒性、耐油性、耐水性、化學穩(wěn)定性和電氣性能。水、無機鹽、堿、酸類對ABS幾乎無影響，在酮、醛、酯、氯代烴中會溶解或形成乳濁液，不溶于部分醇類及烴類溶劑，但于烴長期接觸會軟化溶脹，ABS塑料表面受冰醋酸、植物油等化學藥品的侵蝕會硬氣放映開裂。ABS有一定的硬度和尺寸穩(wěn)定性，易于成型加工。經過調色可陪成任何顏色。其缺點是耐熱性不高，連續(xù)工作溫度為70℃左右，熱變形溫度約為93℃左右。耐氣候性差，在紫外線作用下易變硬發(fā)脆。 成型特點： ABS在升溫時粘度增高，所以成型壓力較高，塑料上的脫模斜度宜稍大；易產生熔接痕，模具設計時應注意盡量減小澆注系統(tǒng)對料流的陰力；在正常的成型條件下，壁厚、熔料溫度及收縮率影響極小。要求塑件精度高時，模具溫度可控制在50~60oC，要求塑件光澤和耐熱時，應控制在60~80 oC。用柱塞式注射機成型時， 料溫180~230℃注射機壓力（1000~1400）×105P 共 26 頁 第 3 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 2、 塑件體積 V=40×40×9—38×38×8—π×22×4+0.5×15×17=3690.26 材料ABS δ1=0.100% δ2=0.200% ∴δ=0.15% 比 重： 1.03~1.07 拉伸強度： 27.6~55.2 剛 度： 1.38~3.45 擴 展 率： 0.27 m3/s 導熱系數： 0.293 w/ mk 比 熱 容： C=1.047 J/ kg..k 密 度： ρ=1050 kg/ m2 塑件質量： m=ρv=1050×103×3690.26×10-9=3.875 g 3、模具用鋼 選用45# 熱處理正火 規(guī)格φ25 ［δb］≤600 ［σs］≤355 HRC［HB］ (149~127) E=204000 熱導入率 1949.8 w/m.k 參見《塑 料成型工藝與模具設計》表3-1 P55 共 26 頁 第 4 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 4、 塑料冷卻時間 水冷：40℃ φ=9.28 5、 型腔確定 塑料為熱塑性，為了使模具簡單，采用推板+頂針+推出，為提高效率采用一模四腔非平衡式布排 6、注射機確定，假設工廠具有此設備，根據所需注射量采用 XS—ZS—22型柱塞式注射機 參數如下： 額定注射量： 200 cm3 柱塞 直徑： 20×2 mm 注射 壓力： 117MPa 注射 行程： 130 mm 注射 時間： 0.5s 合 模 力： 250KN 鎖 模 力： 250KN 最大成型面積： 90 cm2 最大開模行程： 160 mm 模具最大厚度： 150 mm 注射機型 號參見《塑 料成型工藝與模具設計》表4-1 P100 共 26 頁 第 5 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 模具最小厚度： 60 mm 動定模固定板尺寸： 250×250 mm 拉料 空間： 235 合模 方式： 液壓 7、模具厚度確定 Hmin＜H＜Hmax 繪制圖 校核 H=155 符合 8、開模距確定 Smax≥S=H1+H2+5~10=35+9=50 mm 共 26 頁 第 6 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 二 模具設計 1、主流道設計 澆注系統(tǒng)一般由主流道、分流道、澆口和冷料穴等四部分組成。 澆注系統(tǒng)的設計應保證塑件熔體的流動平穩(wěn)、流程應盡量短、防止型芯變形、整修應方便、防止制品變形和翹曲、應與塑件材料品種相適用、冷料穴設計合理、盡量減少塑料的消耗。 根據塑件的形狀采用推桿推出。由于采用復式點澆口，雙分型面，分流道采用半圓形截面，分流道開設在中間板上，在定模固定板上采用澆口套, 不設置冷料穴和拉料桿。 圖 共 26 頁 第 7 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 W=（117.9×404/32.2×0.4×106×0.2）1/3=4.814 mm 型腔冷卻計算： A=GΔi/［3600φ（1000v）0.8/d0.2（TW—TG）（m2）］ 水管直徑為φ10 長： 180 mm 查表 φ值： 4 熱 焰： 300000 J/kg 模具溫度： 60℃ 冷卻水溫取天然水： 20℃ 流速為： 5×10-5 m/s 冷卻水總熱面積： A=0.75㎡ 所需 水管長度： L=GΔi/3600πφ（1000vd）0.8（TW×TQ）m 2、定模設計 a 確定型腔數 考慮效率初步采用一模四腔 確定鎖模力，成型面積校核 塑件整件表面積： 4×S=4×40×40 mm2 x面積： S`=S+S流=4×100+5768 =6168 mm2 共 26 頁 第 8 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 取6200 mm2 小于90 cm2 又注射量校核 單個塑件體積： V=2610.07 cm3 V1=4×2610.07=10440.14 V= V1rV流=4×100×2+10440.14+π×4×35 =11810.1＜20 cm3 故可取 b、確定定模厚度 條件： 1、 制件壁厚在滿足結構和成型工藝條件下要求均勻一致 2、 結構，強度適當 3、 脫模強度 4、 承受沖擊力均勻分布 5、 防止金屬嵌件裂紋 6、 孔嵌件出現焊接處能得到加強 7、 防止薄壁處的熔接痕 8、 防止壁厚處縮孔 9、 防止刃口狀部位以及薄壁處的充填不足 共 26 頁 第 9 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 c、強度計算 W=（DL4/32EZ8）1/3 B—板厚 L—內寬 P—壓力 D—腔深 E—模量 Z—變形 W—側壁厚度 動模板采用： 180×180 mm 符合溫度校核水管長： 0.18 m 共 26 頁 第 10 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 20 180 15 56 180 20 70 6 x ? 10 4 x ? 12 3、支撐板設計 1、 板厚校核： W= （5PBD4/32E7Z）1/3 B= 38㎜ P= 117Mp B= 45＃（204000） T= 180㎜ D= 120 Z= 0.1㎜ 共 26 頁 第 11頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 得： W= 15.447㎜ 取 20㎜ （見上頁標意圖） 4、 排溢系統(tǒng)設計 1）、利用配合間隙排氣，其間隙均為： 0.03~0.05㎜ 2）、分流道端部開設冷料穴來容納前鋒冷料以保證塑料件質量 3）、由于強行脫模，本模具不開設拉料桿 5、推出機構設計 為了擴大同壓面積，采用推板推出 推板上開有導柱孔，銷孔，型芯裝配孔和排氣系統(tǒng)機構 1、 推板開在動模側 2、 采用平板使其受力均勻 3、 設計四根推桿將推板推出，推桿分布均勻，使其受力均勻 4、 合模由推板復位，正確復位 脫模力計算 ΣFx=0 共 26 頁 第 12 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 Ft+FbSinα=FCosα Fb——塑件對型芯的包緊力； F——脫模時型芯所受的摩擦力 Ft——脫模力； Α——型芯的脫模斜度。 又 F=Fbμ 于是 Ft=Ap（μCosα—Sinα） 而包緊力為包容型芯的面積與單位面積上包緊力之積，即： Fb=Ap 由此 可得： Ft=Ap(μcosα-sinα) 式中：μ——為塑料對鋼的摩擦系數，約為0.1~0.3； A——為塑件包容型芯的總面積； P——為塑件對型芯的單位面積上的包緊力，在一般情況下，模外冷卻的塑件p取2.4~3.9×107Pa;模內冷卻的塑件p約取0.8~1.2×107Pa。 所以:經計算，A=0.75㎡ ,μ取0.2,p取2.5×107Pa,取α=45′。 Ft=7500×10-6×2.5×107(0.2×cos45′-sin45′) =605.176×107Pa 共 26 頁 第 13 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 (推板) 共26 頁 第 14頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 6、 合模導向機構設計 導柱導向機構是保證動定?；蛏舷履：夏r，正確定位和導向的零件。 一、 導柱導向機構的作用： 1、 定位件用：模具閉合后，保證動定?；蛏舷履Ｎ恢谜_，保證型腔的形狀和尺寸精確，在模具的裝配過程中也起定位作用，便于裝配和調整。 2、 導向作用：合模時，首先是導向零件接觸，引導動定?；蛏舷履蚀_閉合，避免型芯先進入型腔造成成型零件損壞。 3、 承受一定的側向壓力。 導柱導套的選擇： 一般在注射模中，動、定模之間的導柱既可設置在動模一側，也可設置在定模一側，視具體情況而定，通常設置在型芯凸出分型面最長的那一側。而雙分型的注射模，為了中間板在工作過程中的支承和導向，所以在定模一側一定要設置導柱。 導柱、導套盡量采用標準結構 定位采用定位銷φ10 導柱：采用φ10 φ12 如下圖示： 共 26 頁 第 15頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 7、內型腔設計計算 1、產生偏差的原因： ①．塑料的成型收縮　　　成型收縮引起制品產生尺寸偏差的原因有：預定收縮率（設計算成型零部件工作尺寸所用的收縮率）與制品實際收縮率之間的誤差；成型過程中，收縮率可能在其最大值和最小值之間發(fā)生的波動。 σs=(Smax-Smin)×制品尺寸 σs——成型收縮率波動引起的制品的尺寸偏差。 Smax、Smin —分別是制品的最大收縮率和最小收縮率。 　　　　　　　　　 ②．成型零部件的制造偏差　　工作尺寸的制造偏差包括加工偏差和裝配偏差。 ③．成型零部件的磨損 共 26 頁 第 16 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 取X=0.5 δz=Δ/3 ABS收縮率 δ1=0.20% δ2=0.10% ∴δ=0.150% Lm+δz=[（1+ˉ s）（s-xΔ）ˉ ] 0+δz LM1=[（1+0.15%）×38—0.5Δ] 0+δz =36.2460+0.17 LM0-δz=[（1+0.15%）×40+0.5×Δ] 0-δz HM0+δz=[（1+0.15%）×8 – 0.5×Δ] 0+δz =8.400+0.17 HM0-δz =[（1+0.15%）×9+0.5×Δ] 0-δz =9.41750-0.17 Cm±δz/2 =（1+0.15%）×24±δz/2 =24.13±0.085 Cm±δz/2 =（1+0.15%）×15±δz/2 =14.245±0.085 收縮率見《塑料成型工藝與 模具設計》 附錄B 計算參考 《塑料成型工藝與 模具設計》 第五章第三節(jié) P151 共 26 頁 第 17 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 （動模） 共 26 頁 第 18 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 ABS屬中粘度塑料 δ≤0.05 塑料尺寸 40屬于10~50中 δ=40/[3（1+Δi）] 取中等 δ=0.2613（1+0.26） =0.069 取 0.07 共 26 頁 第 19頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 2、成型零件的強度、剛度計算 注射模在其工作過程需要承受多種外力，如注射壓力、保壓力、合模力和脫模力等。如果外力過大，注射模及其成型零部件將會產生塑性變形或斷裂破壞，或產生較大的彈性彎曲變形，引起成型零部件在它們的對接面或貼合面處出現較大的間隙，由此而發(fā)生溢料及飛邊現象，從而導致整個模具失效或無法達到技術質量要求。因此，在模具設計時，成型零部件的強度和剛度計算和校核是必不可少的。 一般來說，凹模型腔的側壁厚度和底部的厚度可以利用強度計算決定，但凸模和型芯通常都是由制品內形或制品上的孔型決定，設計時只能對它們進行強度校核。 因在設計時采用的是鑲嵌式圓形型腔。因此，計算參考公式如下： 側壁： 按強度計算： 按剛度計算： 計算參考 《塑料成型工藝與 模具設計》 第五章第三節(jié) P153 共26 頁 第 20 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 按剛度計算： 凸模、型芯計算公式： 按強度計算： 按剛度計算： 由公式分別計算出相應的值為： 按強度計算得：tc=19.43mm th=34.23mm r=32.68mm 按剛度計算得：tc=4.53mm th=21.45mm r=19.32mm 參數符號的意義和單位： Pm 模腔壓力（MPa）取值范圍50~70； E 材料的彈性模量（MPa）查得2.06×105； σp 材料的許用應力（MPa）查得176.5； u 材料的泊松比 查表得0.025； 共 26 頁 第 21 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 δp 成型零部件的許用變形量（mm）查得0.05； 采用材料為3Gr2W8V，淬火中溫回火，≥ 46HRC。 8、推桿設計 采用4根φ12推桿（如下圖） 擋釘采用 d=φ8 共 26 頁 第 22 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 9、溫控系統(tǒng)設計 基本原則：熔體熱量95%由冷卻介質（水）帶走，冷卻時間占成型周期的2/3。 注射模冷卻系統(tǒng)設計原則： 1.冷卻水道應盡量多、截面尺寸應盡量大 型腔表面的溫度與冷卻水道的數量、截面尺寸及冷卻水的溫度有關。 2．冷卻水道至型腔表面距離應盡量相等 當塑件壁厚均勻時，冷卻水道到型腔表面最好距離相等，但是當塑件不均勻時，厚的地方冷卻水道到型腔表面的距離應近一些，間距也可適當小一些。一般水道孔邊至型腔表面的距離應大于10mm，常用12~15mm. 3．澆口處加強冷卻 塑料熔體充填型腔時，澆口附近溫度最高，距澆口越遠溫度就越低，因此澆口附近應加強冷卻，通常將冷卻水道的入口處設置在澆口附近，使?jié)部诟浇哪＞咴谳^低溫度下冷卻，而遠離澆口部分的模具在經過一定程度熱交換后的溫水作用下冷卻。 4．冷卻水道出、入口溫差應盡量小 如果冷卻水道較長，則冷卻水出、入口的溫差就比較大，易使模溫不均勻，所以在設計時應引起注意。 冷卻水道的總長度的計算可公式： Lw=Aw/π 參考《塑料成型工藝與 模具設計》 第五章第七節(jié) P226 共26 頁 第 23頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 Lw 冷卻水道總長度 Aw 熱傳導面積 Dw 冷卻水道直徑 根據模具結構要求，冷卻水道長度 5．冷卻水道應沿著塑料收縮的方向設置 聚乙烯的收縮率大，水道應盡量沿著收縮方向設置。 冷卻水道的設計必須盡量避免接近塑件的熔接部位，以免產生熔接痕，降低塑件強度；冷卻水道要易于加工清理一般水道孔徑為10mm左右，不小于8mm。根據此套模具結構，采用孔徑為8mm的冷卻水道。 冷卻系統(tǒng)的結構設計： 中等深度的塑件，采用點澆口進料的中等深度的殼形塑件，在凹模底部附近采用與型腔表面等距離鉆孔的形式。 共 26 頁 第 24 頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 10、設計小結 通過這次系統(tǒng)的注射模的設計，我更進一步的了解了注射模的結構及各工作零部件的設計原則和設計要點，了解了注射模具設計的一般程序。 進行塑料產品的模具設計首先要對成型制品進行分析，再考慮澆注系統(tǒng)、型腔的分布、導向推出機構等后續(xù)工作。通過制品的零件圖就可以了解制品的設計要求。對形態(tài)復雜和精度要求較高的制品，有必要了解制品的使用目的、外觀及裝配要求，以便從塑料品種的流動性、收縮率，透明性和制品的機械強度、尺寸公差、表面粗糙度、嵌件形式等各方面考慮注射成型工藝的可行性和經濟性。模具的結構設計要求經濟合理，認真掌握各種注射模具的設計的普遍的規(guī)律，可以縮短模具設計周期，提高模具設計的水平。 共 26 頁 第 25頁 湖南工學院畢業(yè)設計 計 算 內 容 說 明 11、參考資料： [1]屈華昌主編.塑料成型工藝與模具設計.北京：機械工業(yè)出版社，1995 [2]黃毅宏、李明輝主編模具制造工藝.北京：機械工業(yè)出版社，1999.6 [3]《塑料模設計手冊》編寫組編著.塑料模設計手冊.北京：機械工業(yè)出版社，2002.7 [4] 李紹林，馬長福主編.實用模具技術手冊.上海：上海科學技術文獻出版社，2000.6 [5] 王樹勛主編.注塑模具設計與制造實用技術.廣州：華南理工大學出版社，1996.1 [6] 李紹林主編.塑料·橡膠成型模具設計手冊. 北京：機械工業(yè)出版社，2000.9 共 26 頁 第 26頁 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 微型光學產品，如微透鏡或微透鏡陣列已廣泛應用于光學數據存儲、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)模生產的微型光學產品的成本尤為重要。由于其優(yōu)越的生產和再生產能力，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，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)。