臺灣博碩士論文加值系統

塑膠具有易成型、低成本、良好的透明性…等優點，厚件射出成型，是汽車車燈未來一大趨勢，但厚件產品凹陷造成品質不良是一大問題。本文以壓克力(PMMA)車燈魚眼產品(厚17.5mm)為例，解析厚件產品由於內部積熱，造成脫模後產品表面溫度回昇，導致表面凝固層被二次加熱，產生軟化及表面凹陷的現象。同時開發一套動態量測系統，可線上量測產品脫模後表面凹陷隨時間的變化過程。文中將探討製程參數，如膠溫、模溫、保壓時間、保壓壓力、冷卻時間…等，對回溫現象、凹陷程度、品質的特性影響，同時搭配3D電腦輔助分析技術，驗證理論分析與實際凹陷行為之一致性。研究結果可用於預估厚件成型射出時，最適當的冷卻時間，避免因冷卻時間不足，導致產品脫模後表面凹陷，或冷卻時間過長，降低生產效率等缺陷。
研究結果顯示，厚件產品冷卻時間不足脫模後具有回溫現象，影響回溫現象因子主要以溫度為主，造成凹陷的影響跟壓力有關，冷卻時間只要大於回溫現象時間即可脫模，即時量測發現表面凹陷只發生於凝固層未凝固階段，後段以體積收縮為主，分析軟體方面可以預測回溫現象與表面凹陷，使厚件產品開模前可以發現成型不良問題。

Plastic has advantages of easy molding, low cost and good transparency... etc. In the future, thick-walled injection molded part will be a trend of car head lights. However, the poor quality of the thick-walled part was cause by sink mark, and lead to a major issue. In this paper, we take acrylic (PMMA) fish lens for car lights (17.5mm thick) as an example to analyze the heat transfer and shrinkage phenomenon. Due to internal accumulated heat of thick-walled part, the surface temperature was raised after ejection, resulting in frozen layer of surface reheated and causing surface soften and sink mark. A dynamic measurement system was developed to measure the surface sink mark real time after demolding. This study will explore process parameters, like as melt temperature, mold temperature, packing time and packing pressure, etc., to analyze the efficiency between reheat phenomenon, sink mark and quality characteristic, at the same time, 3D computer assisted engineering (CAE) was adopted to analyze the shrinkage and compare the theoretical data and measurement data of sink mark. The results can be used to predict the optimum cooling time of thick-walled part injection molding, and prevent surface sink mark after demolding cause of unsufficient cooling time. The production efficiency can be increased with the optimum cooling time.
The result shows thick-walled part is reheated after demolding due to unsufficient cooling time. The main factor of influencing reheat phenomenon is temperature. Surface sink mark is caused by pressure. Once cooling time is longer than reheating, it is time to demold. Measuring surface sink mark in time only happen in reheat phenomenon. Back end process focus on volume shrinkage. In respect of analyzing software, it can predict reheat phenomenon and surface sink mark precisely, which can detect the problem of bad injection in thick-walked part before molding.
The result shows thick-walled part is reheated after demolding due to unsufficient cooling time. The main factor of influencing reheat phenomenon is temperature. Surface sink mark is caused by pressure. Once cooling time is longer than reheating, it is time to demold. Measuring surface sink mark in time only happen when frozen skin is not solidified. Back end process focus on volume shrinkage. In respect of analyzing software, it can predict reheat phenomenon and surface sink mark , which can detect the problem of bad injection in thick-walked part before molding.

摘要 I
ABSTRACT II
誌謝 IV
目錄 V
圖目錄 VII
表目錄 XI
第一章、 緒論 1
1.1前言 1
1.2研究動機與目的 2
1.3文獻回顧 3
1.4論文架構 11
第二章、 基本原理簡介 12
2.1透鏡簡介 12
2.1.1透鏡的焦點及焦距 12
2.2射出成型原理 14
2.3殘留應力 17
2.4模具熱傳 19
2.4.1模具表面溫度對冷卻時間之影響 21
2.5回溫現象 21
2.6表面凹陷 22
第三章、 模具設計與治具設計 25
3.1模具設計 25
3.1.1產品幾何外型設計 25
3.1.2分模線 25
3.1.3流道系統 26
3.1.4冷卻系統 26
3.1.5頂出系統 27
3.1.6模座之選擇 27
3.2治具設計 28
3.2.1線上即時量測治具 28
3.2.2簡易光學量測治具 30
第四章、 實驗規劃與成品檢測 31
4.1實驗流程 31
4.2實驗材料與設備 33
4.2.1實驗材料 33
4.2.2實驗設備 34
4.3成品檢測 43
4.3.1回溫現象量測 43
4.3.2表面凹陷量測 44
4.3.3殘留應力量測 46
4.3.4光學性質量測 47
第五章、 CAE模擬分析 48
5.1CAE模擬分析 48
5.1.1模擬分析建立 48
5.1.2製程參數設定 55
第六章、 結果與討論 67
6.1厚件產品脫模後的表面回溫現象 67
6.2製程參數與回溫現象的關係 70
6.3回溫現象對產品品質的影響 77
6.3.1表面凹陷 77
6.3.2即時量測與長時間量測 86
6.3.3殘留應力 88
6.3.4光學性質 93
6.4模擬與實驗比對 99
6.4.1回溫現象 99
6.4.2表面凹陷 100
第七章、 結論與未來展望 103
7.1結論 103
7.2未來展望 104
參考文獻 105

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