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磨粒加工對硬脆材料表面完整性影響之研究

An Investigation of the Effects of Abrasive Machining on Surface Integrity of Brittle Materials

作者:廖永源
畢業學校:國立成功大學
出版單位:國立成功大學
核准日期:2009-11-27
類型:Electronic Thesis or Dissertation
權限:Copyright information available at source archive--National Cheng Kung University....

中文摘要

了解與掌握磨粒加工製程對工件表面型態、相變化和殘留應力等形成之影響可幫助控制表面完整性之特徵及選用適當研磨參數以達到最佳砂輪效能或加工效率。本論文分別進行單刃劃切與研磨探討加工條件對單晶矽(100)表面完整性之影響。
首先在單刃劃切實驗中,發現比切削能的改變不但反映出材料尺寸效應,還有材料移除行為的轉變,而這個隨著切削深度改變的比切削能現象進一步被證實可提供作為估算臨界切削深度之準則。接著在不同切削速度、方式與正向負載等加工參數下,分析延性刮削單晶矽(100)所引起的相變化,應力釋放率此製程特徵值被證實可成功地用於判認矽相的轉變。在應力釋放率小於100 GPa/s時矽材料結構由金屬相Si-II轉變為亞穩定相Si-XII/Si-III,而應力釋放率大於150 GPa/s則導致a-Si的形成。
進一步,本文針對一般常用磨粒加工製程如溝槽與平面研磨探討研磨參數對材料移除機制、相變化和殘留應力之影響。在溝槽研磨實驗中,本文結合研磨製程的運動幾何特徵與材料脆性破壞指標,定義未變形最大切屑厚度與臨界切削深度之比值為切厚比,用於探討未變形切屑厚度對邊緣破損品質與砂輪效能之影響。實驗結果指出邊緣崩裂大小如預期隨著切厚比上升而增加,以及發現在單位切厚比時有最佳的研磨比,值適材料移除機制處於延脆轉換點。最後,在固定砂輪速度的平面研磨研究中,切屑負載對矽表面形成機制、相變化和殘留應力的影響以及三者之間的關係已被探討。結果指出較大切屑負載的研磨條件不但使得加工面具有較大的橫向殘留壓應力,而且形成亞穩定相Si-III/Si-XII,而當切屑負載較小則易導致a-Si形成與較低的殘留應力。

英文摘要

Understanding the effects of abrasive machining on the material removal mechanism and surface integrity of brittle materials, such as phase transformation and residual stress, can help selection of optimal conditions for ductile-regime machining of brittle material, and give the insights into the formation of phase change and residual stress on machined surface. In this thesis, experiments in scratching and grinding have been conducted to investigate the effect of cutting conditions on surface integrity of single crystalline silicon (100).
In the scratching experiment, it is found that the material size effect in the ductile region as well as the transition in material removal behavior is well reflected by the change in the specific cutting energy. It is shown that the change of specific cutting energy as a function of the cutting depth can serve as a criterion for estimating the critical depth of cut. By analyzing phase changes in the grooves for ductile scratching on single crystals silicon (100) under various cutting conditions, this study shows that stress release rate can serve as a process characteristic value to predict the transition of phase changes. Si-II is shown to transform to the metastable Si-XII/Si-III phase upon a stress release rate smaller than 100 GPa/s whereas the amorphous forms at stress release rate larger than 150 GPa/s.
The silicon grinding processes including groove and surface grinding are carried on the effects of grinding parameters on removal mechanism, phase transformation and residual stress. In the groove grinding experiment, combining the kinematic features of the grinding process and the material fracture criterion, the cutting depth ratio (CDR), defined as the ratio of the maximum uncut chip thickness to the critical depth of cut of brittle materials, is employed to investigate the effects of uncut chip thickness on groove edge chipping and wheel performance. The experiment results indicate that the magnitude of edge chipping, as expected, steadily increase with increasing CDR, and the optimum grinding ratio is shown to occur at unit CDR, where the material removal mechanism is around the ductile/brittle transition region of the silicon. Finally, this thesis studies the effects of chip loads on surface formation mechanism, near-surface residual stress and phase transformation, and their interrelationships in surface grinding of silicon at a fixed wheel speed. It is shown that grinding condition with higher chip load leads to the formation of Si-III/Si-XII phases as well as a higher transverse surface residual stress while a smaller chip load is favorable in the formation of an amorphous phase and low residual stress.


召集委員 - 李榮顯

口試委員 - 陳朝光

口試委員 - 李驊登

口試委員 - 邱能信

口試委員 - 蔡宗鳴

指導教授 - 王俊志


 

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