本文的目地，在研究並探討圓棒材於行星式三輥輪之輥輪間隙下之變形行為。研究的進行，則使用有限元素法分析軟體“MARC”及選用增量型大變形--大應變彈塑性理論來模擬。網目重分割法之選用則為了避免模擬過程元素因變形過劇造成節點外翻之缺陷致使無法完成模擬製程。整個棒材元素之網目分割均採用三維磚塊元素，並選用大變形三維彈塑性有限元素法模式來執行行星式三輥輪之輥壓製程之模擬。
模擬製程分成三個組別：首先為探討三種不同摩擦值對製程之影響，其次為五種不同偏離角度作用下所產生之製程影響，最後為五種不同的外形輥輪下輥壓製程之探討。在三組模擬情況下所獲得的多項結果如：棒材之等價應力─等價應變分佈、輥輪負載及扭矩、棒材之入、出口速度及其速度比等；這些有用資料可提供為行星式三輥輪之製程設計。

The purpose of this study is to investigate the plastic deformation behavior of a round bar at the roll-gap during the rolling process of a three-roll planetary mill. The analysis is carried out with the aid of a finite element program MARC adopting the large deformation - large strain theory and the updated lagrangian formulation (ULF). A mesh rezoning procedure is also adopted to improve the uncontrollable running error of elements turning inside out. The mesh system of the whole bar billet is created by using three-dimensional brick elements, and the three-dimensional elastic-plastic finite element model in MARC is chosen to perform the simulations of three-roll planetary rolling processes.
The simulation examples consist of three groups. Firstly, three different friction coefficients are adopted to investigate the rolling process. Secondly, totally five different offset angles are used during the simulation of the rolling process. Finally, five different profiles of the roller are used to study the simulation of the rolling process. The successfully obtained numerical results, including equivalent von-Mises stress and plastic strain distributions, rolling force, rolling moment, billet speeds at the entrance and exit planes of the roll-gap are useful in designing the pass schedules of the three-roll planetary rolling processes.

論文目次 目 錄

頁數
摘要 I
ABSTRACT II
目錄 III
圖目錄 V
表目錄 IⅩ
第一章 緒論 1
1.1. 前言 1
1.2. 文獻回顧 4
1.3. 本文組織架構 5
第二章 彈塑性有限元素法之基本理論 6
2.1. 應變及應變率之理論 6
2.2. 應力及應力率之種類 10
2.3. 虛功原理 13
2.4. 有限元素法之離散程序 16
2.5. 接觸問題、摩擦問題及網目重分割問題 17
第三章 H.R.M.輥延製程之有限元素模型 20
3.1 系統之配置和座標之定義 20
3.2 輥輪與棒材之配置和模擬分類 22
3.3 輥延製程之假設條件 29
3.4 輥延製程參數之設定 30
3.5 有限元素法分析 31
第四章 結果與討論 34
4.1 摩擦之影響 35
4.2 輥輪之外形對製程之影響 70
4.3 偏離角變化之影響 90
第五章 結論 107
參考文獻 110

參考文獻 參考文獻

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