超大尺寸之塑膠板片熱成型研製

Thermoforming Process Unprecedentedly Applied to Very Large Size Plastics Plate

呂志賢(Jyh-Shyan Leu)

指導教授 ： 李雄

國立中央大學/工學院/機械工程學系/博士(2015年)

摘要

本論文研究有三部分 (A) ZK60鎂合金晶粒細化之超塑延展性研究 (B) A6061金屬基複合材料運用輥軋和T6處理的組合於氧化鋁強化粒子之效應 (C)超大尺寸之塑膠板片熱成型研製應用。
超塑性鎂合金機械性質採用簡單輥軋製程加上退火處理來細化鎂合金ZK60的晶粒尺寸。這一目標得到有效實現並獲得晶粒細至3.7 μm。這樣的試樣展現出642％的伸長率和其最終斷裂面顯示出顆粒間之分離與顯著晶粒成長。此外，測試樣品的幾何形狀和拉伸試驗軸線相對於超塑成型(Superplastic Forming)之延展性及輥軋方向的影響進行研究。
鋁基複合材料機械性質，Al-Si系合金，具有這樣優異的特性如低重量，低的熱膨脹係數，和高耐磨性，是用於汽車和航空工業的理想材料。然而，它們的應用受到阻礙的主要矽顆粒中的Al-Si系合金的粗化。在這項研究中，對鋁基複合材料的輥軋和T6處理組合效果進行了研究及對鋁基金屬基複合材料的硬度進行了總結。經T6熱處理及輥軋組合，在所有的情況下，硬度提高。此外，鋁基複合材料用不同量的增強Al2O3顆粒中，也討論了磨耗測試。該結果表明，Al2O3顆粒的增加降低了磨耗率。可能的強化機制和環境溫度的影響進行了討論。這種改進的耐磨耗性是由於矽，在高百分比的輥軋下減小粒徑而細化。
以往大量生產液晶電視機，後殼零件都是採用塑膠射出成型(Injection molding)為主，而開發超大尺寸成品，因射出成型模具費用高昂(動輒數十萬美金)，所以採用另一種傳統的塑膠成型法-熱成型(Thermoforming)，生產超大型、量少產品，是值得考慮的，本論文主要是以電腦輔助分析模擬對照熱成型實作厚度分布，所使用之材料為ABS塑膠。而材料在高溫環境中模具的拔模角度與模具壁的摩擦效應，將直接影響材料的變型趨勢，為此本論文使用有限元素套裝軟體ANSYS/LS-DYNA結合實作，分析塑膠板材之熱成型製程，並探討液晶電視機殼最終厚度分布之影響。ANSYS/LS-DYNA有限元素軟體能提供模具設計人員，在零件實際成型之前先做周密的模擬分析，並據以修改模具之外型輪廓，俾利減少測試次數及縮短產品開發時程以便降低成本。

關鍵字

鎂合金（ZK60） ； 伸長率 ； 輥軋製程 ； 晶粒細化 ； 熱成型 ； 有限元素分析

並列摘要

This thesis has three parts (A)ZK60 magnesium alloy grain refinement of superplastic ductility study (B) A6061 metal matrix composites and combination treatment using rolling -T6 strengthening effect of alumina particles (C) Plastic sheet studies of thermoforming applications.
Mechanical properties of superplastic magnesium alloy using a simple rolling process plus annealing to refine the grain size of magnesium alloy ZK60. This goal is effectively achieved, obtaining grains as fine as 3.7μm. Such a specimen shows an elongation of 642% and its ultimate fracture surface exhibits inter-granular separation and significant grain growth. Additionally, the effects of the specimen’s geometry and tensile test axis with respect to rolling direction on superplastic elongation is studied, which has not been done before.
Mechanical properties of aluminum matrix composites, Al-Si alloys, with such excellent properties as low weight, low thermal expansion coefficient, and high wear-resistance, are ideal materials for the automobile and aerospace industries. However, their applications have been hampered by the coarsening of the primary-Si particles in Al-Si alloys. In this study, the rolling-and-T6- treatments effect on A6061/Al2O3 metal-matrix composites is investigated. The A6061/Al2O3 metal-matrix composites with different amounts of reinforcing Al2O3 particles are examined in the aspects of wear resistance and hardness. Upon the T6 treatment, the hardness is enhanced in all cases and is summarized. The results suggest that the increase of Al2O3 particles reduce the wear rate. The possible reinforce mechanisms and the environmental -temperature effects are discussed. This improvement in wear resistance is due to the particle size refinement of silicon at a high percentage-roll-reduction.
Mass production of LCD TVs in the past, back cover part are using plastic injection molding mainly due to the finished product and the development of very large-size injection molding mold costly (tens of thousands of dollars), so using another conventional plastic molding - thermoforming , the production of very large, less product, is worthy of consideration, this thesis is based on computer-assisted analysis of the control thermoforming Implementing thickness distribution of the materials used for ABS plastic. The effects of the opening angle of friction materials in high temperature environments with the mold wall mold, will directly affect the trend variant materials, for use in this paper the finite element software package ANSYS / LS-DYNA binding experiments, analysis of the plastic sheet plastic molding process and to investigate the effect of the LCD TV cabinet thickness distribution of the final. ANSYS / LS-DYNA finite element software can provide mold design, before the actual molding parts do first thorough simulation analysis, and according to modify the shape of the contour of the mold, to serve and benefit to reduce the number of tests in order to shorten the product development process while reducing costs.

並列關鍵字

ZK60 ； Elongation ； Rolling ； Fine grains ； Thermoforming ； Finite element analysis

參考文獻

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