摘 要
TFT-LCD (即是Thin-Film Transistor Liquid-Crystal Display的縮寫，薄膜電晶體液晶顯示器)產品之前後蓋是由塑膠射出成型所製成，在成品長寬尺寸比例較為平均(約4:3)，且塑膠模具的相關開發技術已有一定程度的成熟。然而在LCD TV (即是Liquid Crystal Display Television的縮寫，液晶電視)系列產品中，訴求16:9寬螢幕比例且大尺吋為市場導向。在此類長寬比例偏大的塑膠射出成型前後蓋零件中的模具開發技術上，並未有相關性的資訊建立。本研究將針對液晶電視產品中，屬於外觀之前蓋及後蓋塑膠射出成型件，在模具開發流程中可能發生成品翹曲變形及成型表面異常的現象加以探討分析。
因應產品開發流程的緊縮，身處塑膠模具業界近10年，決定投入此研究。於本研究中針對液晶電視產品從開發模具到試模量產階段可能產生的問題點加以探討，嘗試建立一套開發準則，提供今後設計同類模具的參考。本研究藉由經驗技術的整合、CAD/CAM/CAE的應用與實際模具開發來進行。其成果將可使機械技術傳承資訊化，並對今後教育訓練與新產品開發上有所貢獻。

Abstract
TFT-LCD is the abbreviation of Thin-Film Transistor Liquid-Crystal Display. The front and back covers of the products are made by means of plastic injection molding. The length and breadth ratio is quite uniform (nearly 4:3), and the related development technologies of plastic molding are matured to a certain extent. Among the LCD TV (namely, the abbreviation of Liquid Crystal Display Television) series of products, market orientation is 16:9 wide screen ratio and large sizes. However, there is no related information on the tooling development technologies of such plastic injection molding front and back cover components of larger length and breadth ratio. This study will discuss and analyze the phenomenon of finished product twist deformation and abnormal molding surfaces that I possibly encountered during the process of tooling development for front and back cover molding injection work-piece (appearance) in LCD TV products.
With almost 10 years of experience in the plastic tooling industry, I made the decision to plunge myself into this study of looking at the continuous contraction of the product development process. Possible problems with LCD-TV products from tooling development to molding test and mass production will be discussed in this study. This will be in an attempt to establish a set of rules for development for references when designing similar tooling in the future. This study is accomplished by means of integration of experience and technologies, applications of CAD/CAM/CAE and actual tooling development. The result may enable the passing on of the information of mechanical technologies and contribute to education and training as well as development of new products in the future.

TABLES OF CONTENTS
CHINESE ABSTRACT……………………………i
ENGLISH ABSTRACT………………………… ii
ACKNOWLEDGEMENTS………………………iv
TABLE OF CONTENTS…………………………vi
LIST OF FIGURES……………………………ix
LIST OF TABLES……………………………xi
CHAPTER
Ⅰ Introduction……………………………………….1
Ⅱ Brief Description of TFT-LCD Products……4
2.1 Introduction……………………………………4
2.2 Product trends…………………………………4 2.3 Analysis of industrial structures………7
Ⅲ Injection Molding and Designing Concepts of
Related Tooling….9
3.1 Injection molding of finished plastic
products………………9
3.2 Gas-assisted injection molding of finished
plastic products...12
3.2.1 Principles and functions…………12
3.2.2 Description of characteristics………13
3.2.3 Advantages…………………………………14
3.2.4 Summary……………………………………………16
Ⅳ Problem Analysis of Front Cover Warp and Back Cover Surfaces Issues……………………18
4.1 Analysis of front cover finished product
warp deformation...19
4.2 Analysis of back cover surface imperfection22
4.2.1 Comprehensive discussion…………22
4.2.2 welding line ………………………26
4.2.3 Air trap…………………………27
4.2.4 Silver line………………………29
4.2.5 Sink Mark………………………31
4.2.6 Summary……………………………35
Ⅴ Description of Case of Tooling Design…38
5.1 Case description……………………………38
5.2 Description of key points in front cover
tooling design….….39
5.2.1 Key points for designing cooling systems40
5.2.2 Key points for gas-assisted injection
molding design…..42
5.3 Description of back cover tooling design…43
Ⅵ Discussion of Results…………44
6.1 Discussion of front Cover injection products
finished………44
6.2 Discussion of back cover injection finished
products…48
6.3 Comprehensive conclusion………………53
Ⅶ Conclusion………………………….56
FUTURE PROSPECTS…………………………58
REFERENCES…………………………………60
APPENDIX……………………………………61

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