參考文獻

[1] N-Q. Zhao, X-X. Jiang, C-S. Shi, J-J. Li, Z-G. Zhao and X-W. Du, “Effects of anodizing conditions on anodic alumina structure,” Journal of Materials Science, Vol.42, pp.3878–

3882, 2007.

[2] Y-L. Wang, N-W. Liu, C-Y. Liu, H-H. Wang, “Focused-Ion-Beam-Based Selective Closing and Opening of Anodic Alumina Nanochannels for the Growth of Nanowire Arrays Comprising Multiple Elements,” Adv. Mater. 20, 2547-2551, 2008.

[3] Q. Zhao,” High-density, vertically aligned crystalline CrO2 nanorod arrays derived from chemical vapor deposition assisted by AAO templates,” The Royal Society of Chemistry, pp.3949–3951, 2009.

[4] 詹景翔，“多孔質陽極氧化鋁模板製作似蟬翼抗反射結構”，國立台灣科技大學機械工程研究所，2009.

[5] 陳建志，“ 鍍鋁矽晶圓之多孔質陽極氧化鋁結構製作大面積抗反射結構製程研究”，國立台灣科技大學機械工程研究所，2010.

[6] Shia-Chung Chen, Ying Chang, Tsung-Hai Chang, Rean-Der Chien, “Influence of using pulsed cooling for mold temperature control on microgroove duplication accuracy and warpage of the Blu-ray Disc“International Communications in Heat and Mass Transfer Volume 35 2008, Pages 130-138 , 2008.

[7] R. Bruck, R. Hainberger, R. Heer, N. Kataeva, A. Köck, M. Krapf-Günther, K. Kaiblinger, F.

Pipelka, B. Bilenberg, “Direct replication of nanostructures from silicon wafers in polymethylpentene by injection molding,” Microelectronic Engineering, 2009.

[8] From K. H. Kim , W. Kim , J. C. Hong, H. S. Ko , B. K. Kim , C. Huh , G. Y.

Sung ,”Fabrication of a Nanosize Pattern Embedded Plastic Chip via an Injection Molding Method for Application to an Optical Biosensor,” International Polymer Processing,pp.341-345 2010.

[9] Jong Sun Kim¹, Dong Sung Kim^2,*, Jeong Jin Kang¹, Jong Deok Kim¹, Chul Jin Hwang¹, ,”

Replication and comparison of concave and convex microlens arrays of light guide plate for liquid crystal display in injection molding,” Polymer Engineering & Science Volume 50,

Issue 8, pages 1696–1704, August 2010.

[10] Tofteberg, T.R., Amédro, H., Grytten, F., Andreassen, E. ,” Effects of injection molding holding pressure on the replication of surface microfeatures,”International Polymer Processing 25 (3), pp. 236-241,2010.

計畫查核點自評表

重要工作項目查核內容概述（力求量化表示）

實驗規劃與設計設計實驗流程以及相關儀器找尋

導光元件流澆道設計進行導光元件之流澆道設計

導光元件網格製作將導光元件3D圖檔匯入Rhino製作網格導光元件模擬分析進行初步模擬分析，訂定成型參數

導光元件模具設計

設計符合機台規格之模具晶圓放置方式設計

水路設計射出成形模具設計與

發包與模具廠討論開模及模具材質等事宜

射出成形實驗

(無微結構) 進行無微結構之導光元件射出

PAA模板製作製作結構模板

SEM拍攝將PAA模板進行SEM拍攝射出成形實驗

(有微結構)

將晶圓放置模具內進行有微結構之導光元件射出實驗

實驗數據整理射出實驗數據整理

SEM拍攝導光元件進行SEM拍攝(微結構)

穿透率量測導光元件進行穿透率拍攝並比較

(有、無微結構)

光彈量測導光元件進行光彈量測(微結構)

量測數據整理整理所有量測數據並比較

結案撰寫結案報告

表C012A-3 共頁第頁

附錄 A 全電式射出成形機

FANUC ROBOSHOT α-15iA

附錄 B Asahi Kasei Delpet 80NH PMMA 物性表

Analysis on Injection-Compression Molding for Aspheric Optical Lens

Chao-Chang A. Chen¹, Shao-Hua Chang²

1. Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan

2. Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan

NSC: 100－2221－E－011 －028 ABSTRACT

Currently most polymer optical lenses can be manufactured by injection molding(IM) or injection compression molding(ICM) to achieve high throughput and low cost. However, the residual stress induced by IM/ICM is a critical problem for obtaining a stable dimension, especially for reducing warpage and desired optical property. This paper is to investigate the effect of ICM on the residual stress of aspheric lens. A simulation software, Moldex3D R10, has been used to simulate the filling and packing pressure as well as the residual stress values of optical lenses for ICM process. A photo-elastic instrument has been developed to observe the residual stress distribution. Using ICM the residual stress at the gate location has been proved to be reduced by 2.98%. Results can be further improved for optical injection molding parameters of aspheric lens with micro structure.

Keywords: Injection Compression Molding, Aspheric Optical Lens, Residual Stress,

1. Introduction

Optical lenses read to fulfill quality re-quirements like dimensions, appearance, and optical characteristics. Currently, injection molding(IM) is the most popular method to manu-facture polymer optical lens because of the high throughput and low cost. However, the residual stress induced by IM/ICM process is a critical problem in achieving a stable dimension, es-pecially for reducing warpage and desired op-tical property. ICM to add a compression ac-tion during IM process. ICM uses its time de-lay and ejectoror other retrofit devices to complete the process. According to the time delay of closing mold, the clamping force and the mold closing po-sition, the ICM can be classified into three types: (a) short-shot injection compression molding (b) full-shot injection compression molding, and (c) the injection compression molding[3]. This research uses short-shot injection compression molding to manufacture the optical lens that has been de-signed by Yang[2]. A simulation software Moldex3D R10 has been to simulate the filling and packing pressure, as well as the residual stress values of optical lenses for IM and ICM

process. A full-electric injection machine is used to produce optical lenses by IM and ICM.

A photo-elastic instrument has been developed to observe the residual stress distribution [1].

Finally, results of simulation compared with ex-perimental results have been for short shot and warpage.

2. Simulation and Experiment of ICM 2.1 Simulation

Based on previous design of aspheric lens[2], Figure 1 shows the design parameter of lens. The convex part surface is the fixed half (plate A) of mold insert for IM/ICM.

By exporting the model file into Moldex3D mesh to build the mesh model, the the mesh can be obtained as shown in Table 1. Then Moldex3D R10 with cooling channels are shown in in Figure 2.

2.2 Short-Shot Test

Figure 3 is the results of short-shot test.

Short-shot of ICM mainly uses the position of the metering section of screw to observe the flow front of melted polymer flow. Observing the flow front

gives information about the melted plastics and con-trolling the flow can prevent welding line, air trap and incomplete filling. Furthermore, short-shot of IM/ICM allows calculation of the volume of mate-rial needed to fill the mold by controlling the stroke of the metering section. Table 2 shows parameters of the short-shot experiment. Figure 3 also shows the photos of optical products under injections with different percentage of metering section.

2.3 Parameters of IM/ICM 2.3.1 Injection Molding

Parameters of IM are set to be within the range for proper working condition for the FANUC RO-BOSHOT α15iA. Injection speed of 40mm/s and packing pressure of 3 seconds with multiple stages of packing pressure (30MPa 1s; 20MPa 1s; 10MPa 1s) have been selected. Since the working tempera-ture of the Asahi PMMA Delpet 80NHp plastic is between 230 and 270℃, the melted plastic temper-ature is set to be the midpoint as 250℃. The tem-perature of the mold is fixed at 70℃, and the cool-ing time is 25s.

2.3.2 Injection Compression Molding

ICM is a process that adds a compression ac-tion to the IM, so the parameters for filling are the same as injection speed of 40mms/s, packing pres-sure time of 3s, melted plastic temperature at 250℃, mold temperature at 70℃, and cooling time of 25s.

To achieve a mold clamping speed of 60mm/s, the injection time delay is 0.35s, the mold clamping delay time is 0.5s, and the maximum compression force is 15tf.

For comparison, the IM and ICM parameters described above are organized in Table 3. After us-ing the parameters for simulation analysis and per-forming experiments with the actual lens, these two results are compared and the effect of manu-facturing parameters on the optical lens have been investigated and discussed as in section 3.

3. Result and Discussion 3.1Results of Simulation

Pressure curves at the gate location for IM and ICM are shown in Figure 4, respectively. The maximum pressure at the gate for ICM is 46.61MPa, which is smaller than that of IM, which is 56.83Pa,

by 17.98%. Therefore, at the gate location, the ICM can reduce the pressure of the optical lens used in the experiment effectively.

The residual stress graphs for simulations of IM and ICM are shown in Figure 5, respectively.

The parts in red color have higher residual stress, and that the lens (a) IM has higher residual stress at the center of the lens and close to the gate, while that by ICM only has the higher residual stress close to the gate, with evenly distributed residual stress at other locations of such lens. Slicing the lens in y-axis, it can be seen that for lens by IM the residual stress in the interior is not only greater than that of ICM, but the residual stress of the lens is also une-venly distributed. Therefore that ICM can effec-tively decrease the residual stress in the lens and achieve a more even by distributed optical property.

Moreover, at the gate IM has stress greater than 0.5MPa, while that by ICM gives only few loca-tions with stress greater than 0.5MPA, so the ICM can decrease the stress at the gate location obvious-ly.

3.2 Experimental Results

Aspherical lens have been made by IM and ICM. The photo-elastic instrument is used to ob-serve the residual stress distribution in the optical lens. Figure 6 shows the half order of the white light photo-elastic streaks schematic diagram[1], where the vertical axis represents the intensity and the horizontal axis represents the fringe order, which corresponds to the background color. Starting from the center of the lens to the gate location, the center has a fringe of 0, the pink to purple background has a fringe change from 1 to 2, the blurry blue area between the blue and purple is approximated to have a fringe of 3, and the clearer blue has fringes 4 and 5. The greatest fringe order is 5.2.

Figure 7 is the white light photo-elastic streaks distributions of aspheric lens by IM and ICM.

Comparing Figure 7a and 7b, it is found that the blue band with 5.2 fringe order at the lens gate loca-tion by IM is larger than that of the ICM lens. The white light photo-elastic streaks experiment shows that ICM can effectively decrease the residual stress at gate location.

Using the residual stress detecting software developed in this study, the greatest residual stress at position 5 for IM is 0.402MPa, and is 0.390MPa for ICM. ICM produces a residual stress 0.012MPa which is that by less than IM, as decreasing 2.98%.

Also, the trend of the broken line graph shows that

the residual stress at positions 5 to 8 of ICM de-creases more than that of the IM, Therefore, it is validated that the ICM can decrease the residual stress of the aspherical optical lens than that by IM.

Figure 8 also shows the combined pho-to-elastic results of the simulation and the actual photo-elastic results of the optical product, for both IM and ICM. Comparing the simulation with the actual experimental results, the trend is similar - both show that the optical lens has higher residual stress by IM than that by ICM. Thus the ICM effec-tively decreases the residual stress and improves optical properties of aspheric lens.

4. Conclusion

This study has completed simulation and ex-perimental of aspheric lens for IM and ICM. Pho-to-elastic experiments have used to observe the dif-ference of residual stress distribution and optical properties. Conclusions of this study can be drawn as following.

(1) Simulation and injection experiment both show that the residual stress is concentrated near the gate location. With ICM, the residual stress is clearly less concentrated than that by IM.

(2) According to results of the simulation, ICM evidently decreases the residual stress of the optical lens used in this experiment. The phys-ical property is also more evenly distributed, and the maximum pressure at the gate location has decreased by 17.98%.

(3) The actual injection experiment has been com-pleted and lens have been analyzed by pho-to-elastic analysis method. The residual stress of lens by ICM can be decreased as 2.98% than that by IM.

(4) Comparing the white light photo-elastic streaks and simulated complex photo-elastic results, it can be seen that both results are similar and again validates that ICM can effectively reduce the residual stress and improve the optical property for the aspheric optical lens.

(5) Further application can focus on the ICM of aspheric lens with micro structure.

Acknowledgement

The author wishes to express gratitude to re-gional director-Alice Lin, deputy technical manag-er-Marvin Wang, CAE engineer-Alan Liao, CAE engineer-Alvin Ho, and manager secretary-Vicky

Gau in Taipei CoreTech System Co.,Ltd for their professional and support CAE technical support.

Thank the NSC number 100－2221－E－

011 －028 support the sponsorship on this study.

Reference

1. Chen, Jr-Rung, Chen, Chao-Chang A., Chiou, Horng-Shing , “A White-Light Photoelastic Method for Residual Stress Analysis of PMMA Thin Plates by Injection Molding”, International Symposium on Precision Mechanical Meas-urements (2008).

2. Yang, Li-Chuan, “Analysis of Aspheric Plastic Lens Compensation by Optical Ray Tracing Method”, Department of Mechanical Engineering , National Taiwan University of Science and Technology (2007).

3. Yeh, Ching-Hsien, “Research on Residual Stress and Optical Quality in Hybrid Optical Elements by Vibratile Injection Compression Molding Process”, Department of Mechanical Engineering , National Taiwan University of Science and Technology (2007).

Table 1 Specification of mesh mold.

Cavity volume

Runner volume

Elements Nodes Mesh type (Gate)

Mesh type (Lens) 0.199(cc) 1.750(cc) 382413 205204 Hexa mesh Prism mesh

Table 2 Parameters of the short shot experimental.

Table 3 Parameters of IM and ICM.

Figure 1 Design parameters of aspheric optical lens.[2]

Figure 2 Aspherical optical lens model used in the Moldex3D analysis software.

Figure 3 Short shot experiments at Analysis soft-ware and the actual injection molding process.

(a) The gate pressure diagram in IM process.

Moldex3D analy-sis(Time :sec)

Part(Screw posi-tion :mm)

90% 10

94% 11

98% 12

99% 13

100% 14

(b)The gate pressure diagram in ICM process.

Figure 4 Gate pressure at gate location for IM/ICM

(a) The residual stress generated in the IM.

The residual stress dis-tribution inside ( y-axis cross section )

The residual stress dis-tribution on the surface

(b) The residual stress generated in the IM.

Figure 5 Residual stress of aspheric lens by IM/ICM

Figure 6 Half order of the white light photo-elastic streaks schematic diagram. [1]

(a) IM of the white light photo-elastic streaks and the residual stress diagram .

(b) ICM of the white light photo-elastic streaks and the residual stress diagram.

Figure 7 White light photo-elastic streaks and the re-sidual stress diagram by IM/ICM

The residual stress dis-tribution inside ( y-axis cross section )

The residual stress distri-bution on the surface

Figure 8 The combined photo-elastic results of the mold flow analysis and the actual photo-elastic

re-sults of the optical product, for both IM and ICM.

國科會補助計畫衍生研發成果推廣資料表

日期:2012/11/15

國科會補助計畫

計畫名稱: 多尺度導光元件模造成形分析研究計畫主持人: 陳炤彰

計畫編號: 100-2221-E-011-028- 學門領域: 精密製造技術

無研發成果推廣資料

100 年度專題研究計畫研究成果彙整表

計畫主持人：陳炤彰計畫編號：100-2221-E-011-028- 計畫名稱：多尺度導光元件模造成形分析研究

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Chen, C.-C. A., Shao-Hua Chang, ＇＇ Analysis on Injection-Compression Molding for Aspheric Optical Lens ＇＇ , Proc. of Asian Joint Conference on Advanced Polymer Processing, Hangzhou China, Aug. 23-24, 2012.

陳炤彰, 蕭博文, ＇應用田口法於不均厚光學元件之平坦度改善＇, 中國機械工程學會第二十九屆全國學術研討會論文集, 中山大學高雄, Dec. 7-8, 2012

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本研究成功設計一多尺度導光元件，並經由本模流分析用成功設計出一副具有可交換母模側欲成形模板之模具，此模具有可交換母模側模板之功能，可利於進行一般鏡面之多尺度導光元件及添加具抗反射微結構之多尺度導光元件之成品製作，在可交換模板部分本實驗製作出一般鏡面模板及 PAA 模板，此 PAA 模板也成功地應用於製作具抗反射微結構之多尺度導光元件成品，經實際射出所製作之產品進行光照度實驗，可發現在具有較好入光面形

在文檔中多尺度導光元件模造成形分析研究 (頁 20-34)