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    Please use this identifier to cite or link to this item: http://ccur.lib.ccu.edu.tw/handle/A095B0000Q/163

    Title: 預測冷抽碳鋼棒材中心缺陷與驗證;Numerical Prediction of Central Burst Defect in Cold Draw of Carbon Steel with Experimental Validation
    Authors: 黃彥儒;HUANG, YEN-JU
    Contributors: 機械工程系研究所
    Keywords: 冷抽製程;中碳鋼棒材;有限元素法;中心缺陷;Oyane破壞準則;微結構分析;Cold drawing;Medium carbon steel bars;FEM;Central defects;Oyane fracture criterion;Micro structure analysis
    Date: 2018
    Issue Date: 2019-05-23 12:52:46 (UTC+8)
    Publisher: 機械工程系研究所
    Abstract: 冷間抽製加工技術已發展多年,從早期從銅、鉛材料的線材抽製逐漸發展至棒材,直徑由數公釐至數公分,材質使用上也逐漸提高剛性及強度,鋁合金、碳鋼及鉻鉬鋼等均是目前工業使用上常見的材質,外型輪廓也由簡易的圓棒發展為方棒、多邊棒,近幾年來工業界也能夠運用冷抽生產異形棒材用於線軌、滑塊與結構鋼材等。雖然冷抽製程已發展數十年,不過於工業生產上還是會發生中心缺陷,由於中心缺陷相較於堆積、表面刮除等,不易由外觀觀察而知,且會大幅降低成品強度,因此中心缺陷的研究探討至今也還持續進行。 中心缺陷的探討已經非常有歷史,卻較少有研究將有限元素法之結果與早期的材料流動、速度場分析做探討與整合,隨著電算機的快速發展,有限元素法在近幾年來成為數值模型的主流解析方法,搭配破壞準則以及元素移除或是元素分離法得以將中心缺陷於數值模型上可視化。 本研究將使用有限元素軟體配合Oyane破壞準則、元素移除法將中心缺陷發生時元素的速度分佈做探討,並且配合實驗結果來修正破壞準則中參數,用以預測不同製程條件下的破壞情況。
    Cold drawing process has been developed for many years. For the early stage, as the development of wire drawing for copper and lead, the size of workpoeces increase, which is from millimeter to centimeters in diameter. The materials evolved in cold drawing also demanding hight rigidity and strength. It’s common that aluminum, carbon steel and Cr-Mo steel are used in industry. The profile of the workpiece has also evolved from a simple round to a square and a polygonal. In recent years, industry also produces special shaped bars for use in linear guideway, sliders and structural steels. Although Cold drawing process has been developed for decades, central burst defects has been still a problem in industrial production. Comparing with accumulation and the surface scraping, the central burst defects are hardly observed from the appearance. The strength of the product is significantly reduce when central burst defects occur. Therefore, the central burst defect is still a research topic to this day. Studing about central burst defects has been very historic. Few studies have explored the discussion and integration of finite element methods with material flow and field of velocity analysis. With the rapid development of computer, the finite element method has become the mainstream analytical method of numerical models in recent years. With the fracture criterion and method of element removal or element separating, the central burst defects can be visualized through the numerical model. This research will use the finite element software with Oyane fracture criterion and element removal method to explore the velocity distribution of the element when the central burst defects occur. Cold drawing experiments where also conducted to provide the numerical tool a guide value to modify results are used to revise the parameters in the fracture criterion to predict the damage under different process conditions.
    Appears in Collections:[機械工程學系] 學位論文

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