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河南機(jī)電高等?？茖W(xué)校
畢業(yè)設(shè)計(jì)論文
論文題目： 螺紋蓋注塑模
系 部
專 業(yè)
班 級
學(xué)生姓名
學(xué) 號
指導(dǎo)教師
2006年5 月 15 日
畢業(yè)設(shè)計(jì)（論文）成績
畢業(yè)設(shè)計(jì)成績
指導(dǎo)老師認(rèn)定成績
小組答辯成績
答辯成績
指導(dǎo)老師簽字
答辯委員會簽字
答辯委員會主任簽字
畢業(yè)設(shè)計(jì)/論文任務(wù)書
題目： 螺紋蓋注塑模
內(nèi)容：（1）模塑工藝規(guī)程的編制
（2）注塑模結(jié)構(gòu)設(shè)計(jì)
（3）模具設(shè)計(jì)有關(guān)計(jì)算
（4）模具加熱與冷卻系統(tǒng)的計(jì)算
（5）模具高度的校核
（6）注塑機(jī)有關(guān)參數(shù)的校核
原始資料:
名稱：螺紋蓋注塑模
材料：PS
插圖清單
圖（1） 塑件圖 ………………………………………………………………………1
圖（2） 型腔排列方式 ………………………………………………………………8
圖（3） 主流道襯套 …………………………………………………………………9
圖（4） 推桿 …………………………………………………………………………20
圖（5） 復(fù)位桿 ………………………………………………………………………21
圖（6） 推板 …………………………………………………………………………21
畢業(yè)設(shè)計(jì)/論文說明書目錄
緒論 …………………………………………………………………1
第1章 模塑工藝規(guī)程的編制 ………………………………………3
1.1 塑件的工藝性分析 …………………………………………………3
1.2 計(jì)算塑件的體積和質(zhì)量 ……………………………………………4
1.3 選用成型設(shè)備 ………………………………………………………5
1.4 注射量的校核 ………………………………………………………5
1.5 注射壓力校核和鎖模力校核 ………………………………………5
第2章 注塑模結(jié)構(gòu)設(shè)計(jì)……………………………………………7
2.1 分型面的選擇 ………………………………………………………7
2.2 確定型腔的排列方式 ………………………………………………7
2.3 澆注系統(tǒng)的設(shè)計(jì) ……………………………………………………8
第3章 成型零件工作尺寸的計(jì)算 ………………………………13
3.1 型腔的工作尺寸計(jì)算 ……………………………………………13
3.2 小型芯的計(jì)算 ……………………………………………………14
3.3 螺紋型芯的計(jì)算 …………………………………………………14
3.4 型腔側(cè)厚壁和底板厚度的計(jì)算 …………………………………15
第4章 成型零件材料的選用 ……………………………………17
第5章 合模導(dǎo)向機(jī)構(gòu)的設(shè)計(jì) ……………………………………18
第6章 脫模頂出機(jī)構(gòu)的設(shè)計(jì) ……………………………………19
6.1 推出機(jī)構(gòu)設(shè)計(jì) ……………………………………………………19
6.2 脫模機(jī)構(gòu)設(shè)計(jì) ……………………………………………………19
第7章 其他結(jié)構(gòu)零件的設(shè)計(jì) ……………………………………20
7.1 推桿 ………………………………………………………………20
7.2 復(fù)位桿 ……………………………………………………………20
7.3 模板設(shè)計(jì) …………………………………………………………21
7.4 墊塊設(shè)計(jì) …………………………………………………………21
7.5 支撐柱 ……………………………………………………………21
7.6 推板 ………………………………………………………………21
第8章 模具加熱與冷卻系統(tǒng)的計(jì)算 ……………………………22
8.1 求塑件在硬化四每小時釋放的熱量 ………………………………22
8.2 求冷卻水的體積流量 ………………………………………………22
第9章 模具閉合高度的確定 ……………………………………23
第10章 注射機(jī)有關(guān)參數(shù)的校核 …………………………………24
第11章 繪制模具總裝圖和非標(biāo)準(zhǔn)件零件工作圖 ………………25
第12章 結(jié)論 ………………………………………………………26
致謝 ………………………………………………………………28
參考文獻(xiàn) …………………………………………………………29
（畢業(yè)設(shè)/論文計(jì)題目）
摘要
本課題所設(shè)計(jì)的模具是螺紋注塑模。此模具是典型的三板式模具，即雙分型面注塑模，雙分型面注塑模有兩個分型面，開模時，模具首先沿Ⅰ—Ⅰ面分型分型后澆注系統(tǒng)凝料由此取出；繼續(xù)開模，模具沿Ⅱ—Ⅱ面分型，分型后塑件由此脫出。本塑件采用的材料是流動性和成型性優(yōu)良、成品率高，但易出現(xiàn)裂紋，成型塑件脫模斜度不宜過小的PS。在注射過程中為便于制品成型，應(yīng)盡量縮短塑料在注射過程中的流程。為了不影響塑件的外觀和使用性能此模具采用點(diǎn)澆口形式。為成型塑件的內(nèi)螺紋部分，需要一個螺紋型芯。該模具采用模外手工脫模方式，為保證螺紋型芯在開模時被帶往動模，設(shè)置了由環(huán)形拉簧及卡環(huán)組成的卡環(huán)裝置。為了保證生產(chǎn)的連續(xù)性，螺紋型芯應(yīng)有備件，以供循環(huán)使用。
關(guān)鍵詞： 雙分型面 點(diǎn)澆口 螺紋型芯 卡環(huán)裝置
（畢業(yè)設(shè)計(jì)/論文英文題目）
Abstract
The mould that this subject designs is moulded by the note of the whorl . This mould is a mould of three typical modes in Chinese operatic music, namely a note is moulded in each type, each type a note moulds two type one, while opening the mould, the mould pours the system to congeal the material to take out from this after the dividing type assigning to type Ⅰ- Ⅰ first of all; Continuing opening the mould, the mould moulds one to deviate from from this after the dividing type along the dividing type Ⅱ - Ⅱ Mould pieces of material that adopt mobility and shaping fine, yield high originally, but apt to appear crackle, shaping should not mould pieces of drawing of patterns slope over little PS. In process of injection among for benefit products shaping,should try hard shorten plastics procedure on process of injection. For not influencing this mould of appearance and serviceability which mould one to adopt some runner forms. For shaping mould piece interior whorl part,need one piece whorl type core. This mould adopt mould outside craft drawing of patterns way,for guarantee whorl type the cores while opening the mould take move by mould, Carlos made up of annular extension spring and card ring to set up surround the device. For guarantee produce continuity,whorl type the cores should have spare part,for recycle.
Keyword: Each type Some runner Whorl type core The card surrounds the device
河南機(jī)電高等專科學(xué)校
畢業(yè)設(shè)計(jì)(論文)開題報告
學(xué)生姓名： 學(xué) 號：
專 業(yè)：
設(shè)計(jì)(論文)題目：
指導(dǎo)教師：
2006年4月9日
開題報告填寫要求
1．開題報告（含“文獻(xiàn)綜述”）作為畢業(yè)設(shè)計(jì)（論文）答辯委員會對學(xué)生答辯資格審查的依據(jù)材料之一。此報告應(yīng)在指導(dǎo)教師指導(dǎo)下，由學(xué)生在畢業(yè)設(shè)計(jì)（論文）工作前期內(nèi)完成，經(jīng)指導(dǎo)教師簽署意見及所在專業(yè)審查后生效；
2．開題報告內(nèi)容必須用黑墨水筆工整書寫或按教務(wù)處統(tǒng)一設(shè)計(jì)的電子文檔標(biāo)準(zhǔn)格式（可從教務(wù)處網(wǎng)頁上下載）打印，禁止打印在其它紙上后剪貼，完成后應(yīng)及時交給指導(dǎo)教師簽署意見；
3． “文獻(xiàn)綜述”應(yīng)按論文的格式成文，并直接書寫（或打印）在本開題報告第一欄目內(nèi)，本科學(xué)生寫文獻(xiàn)綜述的參考文獻(xiàn)應(yīng)不少于15篇（專科生不少于10篇，不包括辭典、手冊）；
4．有關(guān)年月日等日期的填寫，應(yīng)當(dāng)按照國標(biāo)GB/T 7408—94《數(shù)據(jù)元和交換格式、信息交換、日期和時間表示法》規(guī)定的要求，一律用阿拉伯?dāng)?shù)字書寫。如“2002年4月26日”或“2002-04-26”。
畢 業(yè) 設(shè) 計(jì)（論 文）開 題 報 告
1．結(jié)合畢業(yè)設(shè)計(jì)（論文）課題情況，根據(jù)所查閱的文獻(xiàn)資料，撰寫1500字左右（本科生200字左右）的文獻(xiàn)綜述(包括目前該課題在國內(nèi)外的研究狀況、發(fā)展趨勢以及對本人研究課題的啟發(fā))：
文 獻(xiàn) 綜 述
在進(jìn)行畢業(yè)設(shè)計(jì)之前，必須做好一切準(zhǔn)備工作，而收集有關(guān)設(shè)計(jì)課題研究方面的資料、文獻(xiàn)是最為重要的。在設(shè)計(jì)工作開始時，只有對課題研究的內(nèi)容有了，充分地了解，才會有設(shè)計(jì)目的和方向；所以收集、查閱有關(guān)文獻(xiàn)資料是必要的。
在現(xiàn)代塑料制件的生產(chǎn)中，合理的加工工藝、高效的、先進(jìn)的模具是比不可少的三項(xiàng)重要因素，尤其是塑料模具對塑料加工工藝要求、滿足塑料制件的使用要求、降低塑料制件的成本起著重要的作用。一副好的注射?？沙尚蜕习偃f次，一副優(yōu)良的壓縮模大約能成型25萬次，這與模具的設(shè)計(jì)、模具材料及模具的制造有著很大的關(guān)系。從塑料模的設(shè)計(jì)、制造及模具的材料等方面考慮，塑料成型技術(shù)的發(fā)展趨勢可以簡單地歸納為以下幾個方面。
㈠ 模具的標(biāo)準(zhǔn)化
為了適應(yīng)大規(guī)模成批生產(chǎn)塑料成型模具和縮短模具制造周期的需要，模具的標(biāo)準(zhǔn)工作十分重視，目前我國模具標(biāo)準(zhǔn)化程度只達(dá)20%。當(dāng)前的任務(wù)是重點(diǎn)研究開發(fā)熱流道標(biāo)準(zhǔn)元件和模具溫控標(biāo)準(zhǔn)裝置；精密標(biāo)準(zhǔn)模架、精密導(dǎo)向件系列；標(biāo)準(zhǔn)模板及模具標(biāo)準(zhǔn)件的先進(jìn)技術(shù)和等向性標(biāo)準(zhǔn)化模塊等。
㈡ 加強(qiáng)理論研究
隨著塑料制件的大型化和復(fù)雜化，模具的重量大數(shù)噸至十多噸，這樣大的模具，若只憑借經(jīng)驗(yàn)來設(shè)計(jì)，往往會因設(shè)計(jì)不當(dāng)而造成模具報廢，數(shù)十萬元的費(fèi)用將毀于一旦，所以設(shè)計(jì)模具已經(jīng)逐漸向理論設(shè)計(jì)方面發(fā)展，這些理論設(shè)計(jì)包括模具剛度、強(qiáng)度的計(jì)算和充型流動理論的建立。
㈢ 塑料制件的精密化、微型化和超大化
為了滿足各種工業(yè)產(chǎn)品的使用要求，塑料成型技術(shù)正朝著精密化、微型化和超大化等方面發(fā)展。精密注射成型是能將塑料制件尺寸公差保持在0.01～0.001mm之內(nèi)的成型工藝方法，其制件主要用于電子、儀表工業(yè)。微型化的塑料制件要求在微型的設(shè)備上生產(chǎn)。目前，德國已經(jīng)研究出注射量只有0.1g的微型注射機(jī)，可生產(chǎn)0.05g左右的微型注射成型塑件。國內(nèi)目前已有0.5g的注射機(jī)，可以生產(chǎn)0.1g左右的微型注射塑件。注射塑件的大型化要求有大型、超大型的注射成型設(shè)備。目前，法國已擁有注射量為17萬g的超大型注射機(jī)，合模力為150MN；國產(chǎn)注射機(jī)的注射機(jī)的注射量也已達(dá)3.5g，合模力為80MN.
在中國，人們已經(jīng)越來越認(rèn)識到模具在制造中的重要基礎(chǔ)地位，認(rèn)識到模具技術(shù)的高低，已成為衡量一個國家制造水平高低的重要標(biāo)準(zhǔn)，并在很大程度上決定著產(chǎn)品質(zhì)量效益和新產(chǎn)品的開發(fā)能力，許多模具企業(yè)十分重視技術(shù)發(fā)展，加大了用于技術(shù)進(jìn)步的投資力度，將技術(shù)進(jìn)步視為企業(yè)發(fā)展的動力，此外，許多研究機(jī)構(gòu)和大專院校開展模具技術(shù)的研究和開發(fā)。美國工業(yè)界認(rèn)為“模具工業(yè)是美國工業(yè)的基石”， 日本則稱“模具是促進(jìn)社會繁榮富裕的動力”，事實(shí)上在儀器儀表、家用電器、交通、通訊和輕工業(yè)等各行業(yè)的產(chǎn)品零件中，有70%以上是采用模具加工而成的。工業(yè)先進(jìn)的發(fā)達(dá)國家，其模具工業(yè)產(chǎn)值早已超過機(jī)床行業(yè)的產(chǎn)值。據(jù)1991年統(tǒng)計(jì)，日本模具工業(yè)已實(shí)現(xiàn)了高度的專業(yè)化，標(biāo)準(zhǔn)化和商品化，在全國一萬多家企業(yè)中，生產(chǎn)塑料模和生產(chǎn)沖壓模的企業(yè)各占40%。新加坡全國有460家企業(yè)，60%生產(chǎn)塑料模。從以上事實(shí)可以看出，由于塑料成型工業(yè)的發(fā)展，到目前為止，塑料模具已處于同沖壓模具并駕齊驅(qū)的地位。
雖然中國模具工業(yè)在過去十多年中取得令人矚目的發(fā)展，但許多方面與工業(yè)發(fā)達(dá)國家相比仍有較大的差距。例如，精密加工設(shè)備在模具加工設(shè)備中的比重還比較低，CAD／CAE／CAM技術(shù)的普及率不高，許多先進(jìn)的模具技術(shù)應(yīng)用還不夠廣泛等等。特別在大型、精密、復(fù)雜和長壽命模具技術(shù)上存在明顯差距，這些類型模具的生產(chǎn)能力也不夠滿足國內(nèi)需求，因而需要大量從國外進(jìn)。
在查閱、收集有關(guān)資料的時候，不僅使我對模具業(yè)的發(fā)展現(xiàn)狀及發(fā)展趨勢、模具的設(shè)計(jì)與制造技術(shù)等有了更多，更全面地了解；而且收集到了許多有關(guān)本課題的研究，與本課題相關(guān)、相似的東西，查找各種有關(guān)模具設(shè)計(jì)與制造方面的經(jīng)驗(yàn)公式，和經(jīng)驗(yàn)數(shù)據(jù)；通過查閱資料和文獻(xiàn)能夠?qū)⒄n堂上所學(xué)習(xí)到的理論知識，與實(shí)際生產(chǎn)當(dāng)中的實(shí)例相結(jié)合去更好地成設(shè)計(jì)任務(wù)；并且使我在課程設(shè)計(jì)上有了更多的設(shè)計(jì)思路，也有了更多的考慮空間，同時也使我在設(shè)計(jì)的過程中能夠從多方面地去考慮問題——模具設(shè)計(jì)的合理性及對設(shè)計(jì)好的模具在工作過程中可能會出現(xiàn)的問題及解決辦法。
畢 業(yè) 設(shè) 計(jì)（論 文）開 題 報 告
２．本課題的研究思路（包括要研究或解決的問題和擬采用的研究方法、手段（途徑）及進(jìn)度安排等）：
1. 先通過收集和查閱各種文獻(xiàn)資料和與同學(xué)老師的交流、指導(dǎo)，對目前國內(nèi)外的模具（塑料模具）的發(fā)展?fàn)顩r和發(fā)展趨勢進(jìn)行深入的了解，預(yù)計(jì)用時間三天。
2. 拿到工件的結(jié)構(gòu)簡圖，對工件進(jìn)行結(jié)構(gòu)形狀、尺寸精度、加工工藝性等方面作出詳細(xì)地分析，并查閱相關(guān)資料看是否符合常規(guī)零件結(jié)構(gòu)設(shè)計(jì)根據(jù)塑件的形狀大小、結(jié)構(gòu)特點(diǎn)、尺寸精度、批量大小以及模具制造的難易、成本高低等確定型腔的數(shù)量與排列方式，預(yù)計(jì)用時兩天。
3. 經(jīng)過對工件的結(jié)構(gòu)工藝性分析，分型面的位置要有利于模具加工、排氣、脫氣、脫模、塑件的表面質(zhì)量及工藝操作等；考慮開模、分型的方法和順序，拉料桿、推桿等脫模零件的組合方式，合模導(dǎo)向與復(fù)位機(jī)構(gòu)的設(shè)置選擇與設(shè)計(jì)；與擬訂可行的塑料工藝方案，并經(jīng)過分析，研究、比較，選擇一種最為合理的塑料工藝作為生產(chǎn)應(yīng)用，估計(jì)用時間兩天。
4. 對模具成型工作零部件進(jìn)行設(shè)計(jì)，主要有螺紋型芯、型腔、定模板、動模板、模架和導(dǎo)柱導(dǎo)套等零件，根據(jù)工作需要的強(qiáng)度來設(shè)計(jì)尺寸，包括各零件的圖紙，如何將模具的各個組成部分通過支撐塊、模板、銷釘、螺釘?shù)戎闻c連接零件，按照使用與設(shè)計(jì)要求組合成一體，獲得模具的總體結(jié)構(gòu)。預(yù)計(jì)需用時間五天。
5. 模具的總裝圖和工作原理（有裝配簡圖）需要用時間兩天。
6. 模具主要零部件的加工工藝過程（螺紋型芯、型腔、定模板、動模板）分析與設(shè)計(jì)，預(yù)計(jì)用時間兩天。
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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(fù)制
B.-K. Lee, D. S. Kim, T. H. Kwon
樸航科技大學(xué)(POSTECH) 機(jī)械工程學(xué)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(shù)。因此我們在近來的研究中非常關(guān)注， 為了進(jìn)一步了解注塑成型在不同的加工條件下對可復(fù)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(jìn)行了大量的試驗(yàn)。 鎳金屬模具嵌件微陣列就是利用改良的LIGA技術(shù)電鍍主裝配的顯微結(jié)構(gòu)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(fù)制的微透鏡陣列的影響。實(shí)驗(yàn)結(jié)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(shí)際運(yùn)用中，能與精細(xì)的光學(xué)元件相媲美。
1 說明
微型光學(xué)產(chǎn)品，如微透鏡或微透鏡陣列已廣泛應(yīng)用于光學(xué)數(shù)據(jù)存儲、生物醫(yī)學(xué)、顯示裝置等各個光學(xué)領(lǐng)域。微透鏡和微透鏡陣列不僅在實(shí)踐應(yīng)用上，而且在微型光學(xué)的基礎(chǔ)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(shù)[1] ，光阻回流進(jìn)程[2]，紫外激光照射[3]等。還有復(fù)制技術(shù)，如注塑模壓成型[4]和熱壓[5]技術(shù) ，這種方法對于減少大規(guī)模生產(chǎn)的微型光學(xué)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(fù)制微觀結(jié)構(gòu)，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(diǎn)，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(jié)構(gòu)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(fù)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(shù)來編制的。注塑成型實(shí)驗(yàn)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(shù)[6]，在一個有機(jī)玻璃板上制造出具有幾種不同直徑微透鏡陣列。此種技術(shù)是先用X光照射有機(jī)玻璃板，然后再進(jìn)行熱處理兩部分構(gòu)成的。X-射線照射引起有機(jī)玻璃分子質(zhì)量的減少，同時降低了玻璃化轉(zhuǎn)變溫度，并因此導(dǎo)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(jié)合改良的LIGA技術(shù)可以預(yù)測微透鏡形狀的變化過程。
在試驗(yàn)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(shù)制造微透鏡陣列作為一個主要的技術(shù)，用來制作鍍鎳的金屬模具的注塑成型。另一些特殊材料，因?yàn)樗鼈兊膹?qiáng)度不夠或熱性能差而不能直接進(jìn)行微細(xì)加工，當(dāng)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(jī)械性能和熱性能的金屬材料，因?yàn)樗鼈兡茉诳蓮?fù)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(fù)制技術(shù)進(jìn)行大批量生產(chǎn)，我們選擇使用金屬模具材料而不是有機(jī)玻璃硅晶體。一些特殊技術(shù)，如低壓注塑成型[8]技術(shù)，應(yīng)該作為良好的復(fù)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(shí)驗(yàn)
傳統(tǒng)注塑機(jī)(Allrounders 220 M，Arburg)多用做實(shí)驗(yàn)機(jī)。注塑模具設(shè)計(jì)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)。