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博碩士論文 etd-0717102-151058 詳細資訊
Title page for etd-0717102-151058
論文名稱
Title
複合材擠製之研究
Study on Extrusion of Composite Rods
系所名稱
Department
畢業學年期
Year, semester
語文別
Language
學位類別
Degree
頁數
Number of pages
107
研究生
Author
指導教授
Advisor
召集委員
Convenor
口試委員
Advisory Committee
口試日期
Date of Exam
2002-06-26
繳交日期
Date of Submission
2002-07-17
關鍵字
Keywords
擠製、複合材
extrusion of composite rods
統計
Statistics
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The thesis/dissertation has been browsed 5663 times, has been downloaded 4257 times.
中文摘要
摘 要
本研究為針對複合材擠製加工提出一滿足速度邊界條件及體積不變的流線函數場,並以此流線函數場建構複合材軸對稱傳統擠製以及靜水壓擠製之解析模式,利用上界法探討複合材於模具內的變形行為模式。本文主要為三部份,(1)複合材傳統軸對稱擠製之解析及實驗,(2)複合材之靜水壓軸對稱擠製之解析及實驗及(3)塑性不安定行為之解析及實驗。
在複合材軸對稱傳統擠製時,本研究提出一組流線函數探討複合材於模具內的變形行為,由流線函數可以推導出塑性區域內之速度場以及獲得剛塑性的邊界的表示式,此解析模式於塑性變形區域內容許芯材與外層材界面有相對的滑動,且於模具出口處成品之芯材與外層材亦容許有速度差。應用圓環壓縮試驗求得模具與材料界面間之摩擦係數,藉由上界法,由總消耗功率之最小化決定模具出口處之芯材半徑比與模具內剛塑性邊界的位置,並利用鋁為芯材,銅為外層材組合之複合材進行擠製實驗,將理論預期之擠製負荷、成品之芯材半徑比及模具內材料流動的模式與實驗結果做比較。
在改變模具出口處芯材與外層材之速度為一致的條件下,即模具出口處芯材與外層材之介面上沒有相對滑動的速度時,本文亦將利用相同的流線函數,模擬複合材之靜水壓擠製的變形行為,預測擠製之加工參數對靜水壓擠製壓力的影響,並亦以內鋁、外銅組合之複合材進行實驗驗證,得理論預期之擠製負荷與實驗比較有良好的一致性。
最後本文亦推導三軸向應力態之塑性不安定的判別式,在模具出口處之芯材與外層材的速度為一致的條件,由模具出口處硬芯材的應力態,推導出塑性不安定判別式之理論,預測內硬外軟之複合材軸對稱擠製時塑性不安定的安全範圍,發現內硬外軟之複合材軸對稱的擠製較易發生塑性不安定,並探討初始斷面積比、材料降伏強度比及硬化指數對臨界斷面積縮減比的影響,進一步以內鋁外鉛組合之複合材做實驗,得在初始面積比為0.15時,理論解析與實驗結果比較,有良好的一致性。

Abstract
A research object of this study is a extrusion of the composite rods. As the condition of the incompressibility, a set of stream functions was proposed by this study to construct analysis model of the conventional and the hydrostatic extrusion. The upper-bound approach was applied to investigate the plastic deformation behavior during composite rods extrusion. The topical subject of this study was consisted of conventional extrusion, hydrostatic extrusion and the instability of composite materials during conventional extrusion.
This study proposes a set of stream functions to investigate the plastic deformation behavior of the rods during axisymmetric extrusion of composite rods through a conical die. The velocity field and the rigid-plastic boundaries can be obtained from the proposed stream functions immediately. Relative slip at the interface of the rods is allowed. The friction factor between the metal and die is determined by a ring compression test. By using the upper-bound approach, the radius ratio of the core layer at the exit of the die and the plastic region within the die are determined by the minimization of the total power. Experiments on extrusion of composite rods composed of aluminum (core layer) and copper (sleeve layer) are also carried out. The predicted force, final radius ratio and flow pattern of the rods within the die are compared with the experimental results.
Being different with conventional extrusion, a condition that has relative slip at the interface of the rods at the exit of the die was modified to become no relative slip. The same set of stream functions with that of the conventional extrusion was also applied to simulate the flow behavior of the composite rods through a conical die during hydrostatic extrusion. This model is used to predict the hydrostatic extrusion pressure for various process parameters via the upper bound theorem. Experiments are also carried out using composite rods composed of copper as the sleeve layer and commercial aluminum as the core layer. The experimental results are compared with the theoretical calculations.
A plastic instability criterion under a tri-axial stress state was developed in this study to predict the occurrence of plastic instability in the hard core layer during axisymmetric composite rod extrusion. Stress states in the hard core layer at the exit of the die, where plastic instability is most likely to occur, were employed to formulate the plastic instability criterion. The effects of various extrusion conditions, such as the initial radius ratio and yield stress ratio of the composite rods, etc., upon the critical area reduction, under which plastic instability can be avoided, were discussed systematically. Furthermore, experiments on composite rod extrusion were also conducted by employing aluminum and lead as layers of composite rods. It was found that the theoretical predictions of the critical area reduction were in good agreement with the experimental measurements with the initial area of 0.15.

目次 Table of Contents
摘要………………………………………………………………………I
英文摘要………………………………………….…………………….III
目錄………………………………………….………………………...V
圖表目錄………………………………………….…………………...VIII
符號說明………………………………………….…………………...XIV
第 一 章 緒論 ……………………………………………….……...1
1-1 前言 ………………………………………………………….....1
1-2 擠製加工的分類 …………………………………………….....2
1-3 複合材擠製之缺陷 …………..………………………………...5
1-4 擠製加工之相關研究 ……………..…………………………...9
1-4-1 單層材傳統擠製 ………..…………………………….......9
1-4-2 複合材傳統擠製 …………………………..………….......9
1-4-3 單層材靜水壓擠製 ………………………………….........10
1-4-4 複合材靜水壓擠製 ………………………………….........11
1-4-5 擠製之塑性不安定 …..……………………………….......12
1-5 研究建構與目的 …..……………………………………….....12
第 二 章 上界限法與流線函數簡介…………….…………………..14
2-1 前言 ……..………………………………………………….....14
2-2 虛功原理..………………………………………………..…....15
2-3 上界限定理..……………………………….…………….…....17
2-4流線函數概要..…………………………………………….…....19
第 三 章 複合材擠製之數學模式..………….……………………..23
3-1流線函數應用於複合材軸對稱傳統擠製之解析.………..…....23
3-1-1 數學模式的推導 ….…………………….………….…......23
3-1-2 擠製消耗功率之計算….………………….…………........34
3-1-3 速度特性分析………………………………...……….......36
3-1-4 解析結果與討論………………………………...…….......39
3-2流線函數應用於複合材軸對稱靜水壓擠製之解析……….....…50
3-2-1 前 言…………………………………………….……........50
3-2-2 速度特性分析………………………………………..........51
3-2-3 解析結果與討論…………………………….…...……......53
第 四 章 複合材擠製塑性不安定性之解析…………………..…….59
4-1 塑性不安定性概要 …..…………………………………….....59
4-2 數學模式推導 …..………………………………………….....60
4-2-1 複合材擠製模具出口處之應力分析 …..…………….......60
4-2-2 降伏函數推導 ……..………………………………….......64
4-3 解析結果與討論 …..…..………………………………..…...68
第 五 章 實驗結果與討論……………………………………….....73
5-1 前言 ………………………………………………………….....73
5-2複合材軸對稱傳統與靜水壓擠製之實驗…………………….....74
5-2-1 擠製實驗機器 ……………………………………….........74
5-2-2 擠製模具之製作 …………………………………….........74
5-2-3 擠製試件之製作 …..………………………………….......78
5-2-4 擠製試件之塑流應力的測定 ……………………….........81
5-2-5 定剪摩擦因子之圓環壓縮試驗 …………………….........85
5-2-6實驗步驟……………………………………………….........86
5-3 複合材擠製之實驗結果與討論 …..………………..….......88
5-3-1 傳統擠製實驗 ………………..……………………….......88
5-3-2 靜水壓擠製實驗 ………………………..…………….......94
5-4 複合材擠製之塑性不安定實驗 ………..…………..………...96
5-4-1 實驗設備 ……………………………………..……….......96
5-4-2 實驗材料 ……………………………………..……….......97
5-4-3 潤滑劑 ……………………………………………..….......98
5-4-4 實驗步驟 ………………………………………..…….......99
5-4-5 塑性不安定之實驗結果與討論 …………………….........99
第六章 結 論 ……………………………………………..........102
6-1 複合材傳統擠製 ……………………………..……..…......102
6-2複合材靜水壓擠製…………………………..………..........103
6-3複合材擠製加工之塑性不安定………………….…...…......103
參考文獻 ……………………………………………………........104
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